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diff --git a/Master/tlpkg/tlperl/lib/Tk/Canvas.pod b/Master/tlpkg/tlperl/lib/Tk/Canvas.pod new file mode 100644 index 00000000000..daf4cf7f32e --- /dev/null +++ b/Master/tlpkg/tlperl/lib/Tk/Canvas.pod @@ -0,0 +1,2394 @@ +# Copyright (c) 1992-1994 The Regents of the University of California. +# Copyright (c) 1994-1996 Sun Microsystems, Inc. +# See the file "license.terms" for information on usage and redistribution +# of this file, and for a DISCLAIMER OF ALL WARRANTIES. +# + +=head1 NAME + +Tk::Canvas - Create and manipulate Canvas widgets + +=for category Tk Widget Classes + +=head1 SYNOPSIS + +I<$canvas> = I<$parent>-E<gt>B<Canvas>(?I<options>?); + +=head1 STANDARD OPTIONS + +B<-background> B<-highlightthickness> B<-insertwidth> B<-state> +B<-borderwidth> B<-insertbackground> B<-relief> B<-tile> +B<-cursor> B<-insertborderwidth> B<-selectbackground> B<-takefocus> +B<-highlightbackground> B<-insertofftime> B<-selectborderwidth> B<-xscrollcommand> +B<-highlightcolor> B<-insertontime> B<-selectforeground> B<-yscrollcommand> + +=head1 WIDGET-SPECIFIC OPTIONS + +=over 4 + +=item Name: B<closeEnough> + +=item Class: B<CloseEnough> + +=item Switch: B<-closeenough> + +Specifies a floating-point value indicating how close the mouse cursor +must be to an item before it is considered to be ``inside'' the item. +Defaults to 1.0. + +=item Name: B<confine> + +=item Class: B<Confine> + +=item Switch: B<-confine> + +Specifies a boolean value that indicates whether or not it should be +allowable to set the canvas's view outside the region defined by the +B<scrollRegion> argument. +Defaults to true, which means that the view will +be constrained within the scroll region. + +=item Name: B<height> + +=item Class: B<Height> + +=item Switch: B<-height> + +Specifies a desired window height that the canvas widget should request from +its geometry manager. The value may be specified in any +of the forms described in the L<"COORDINATES"> section below. + +=item Name: B<scrollRegion> + +=item Class: B<ScrollRegion> + +=item Switch: B<-scrollregion> + +Specifies a list with four coordinates describing the left, top, right, and +bottom coordinates of a rectangular region. +This region is used for scrolling purposes and is considered to be +the boundary of the information in the canvas. +Each of the coordinates may be specified +in any of the forms given in the L<"COORDINATES"> section below. + +=item Name: B<state> + +=item Class: B<State> + +=item Switch: B<-state> + +Modifies the default state of the canvas where I<state> may be set to one of: +normal, disabled, or hidden. Individual canvas objects all have their own +state option, which overrides the default state. Many options can take +separate specifications such that the appearance of the item can be different +in different situations. The options that start with "active" control the +appearence when the mouse pointer is over it, while the option starting +with "disabled" controls the appearence when the state is disabled. + +=item Name: B<width> + +=item Class: B<width> + +=item Switch: B<-width> + +Specifies a desired window width that the canvas widget should request from +its geometry manager. The value may be specified in any +of the forms described in the L<"COORDINATES"> section below. + +=item Name: B<xScrollIncrement> + +=item Class: B<ScrollIncrement> + +=item Switch: B<-xscrollincrement> + +Specifies an increment for horizontal scrolling, in any of the usual forms +permitted for screen distances. If the value of this option is greater +than zero, the horizontal view in the window will be constrained so that +the canvas x coordinate at the left edge of the window is always an even +multiple of B<xScrollIncrement>; furthermore, the units for scrolling +(e.g., the change in view when the left and right arrows of a scrollbar +are selected) will also be B<xScrollIncrement>. If the value of +this option is less than or equal to zero, then horizontal scrolling +is unconstrained. + +=item Name: B<yScrollIncrement> + +=item Class: B<ScrollIncrement> + +=item Switch: B<-yscrollincrement> + +Specifies an increment for vertical scrolling, in any of the usual forms +permitted for screen distances. If the value of this option is greater +than zero, the vertical view in the window will be constrained so that +the canvas y coordinate at the top edge of the window is always an even +multiple of B<yScrollIncrement>; furthermore, the units for scrolling +(e.g., the change in view when the top and bottom arrows of a scrollbar +are selected) will also be B<yScrollIncrement>. If the value of +this option is less than or equal to zero, then vertical scrolling +is unconstrained. + +=back + +=head1 DESCRIPTION + +The B<Canvas> method creates a new window (given +by the $canvas argument) and makes it into a canvas widget. +Additional options, described above, may be specified on the +command line or in the option database +to configure aspects of the canvas such as its colors and 3-D relief. +The B<canvas> command returns its +$canvas argument. At the time this command is invoked, +there must not exist a window named $canvas, but +$canvas's parent must exist. + +Canvas widgets implement structured graphics. +A canvas displays any number of I<items>, which may be things like +rectangles, circles, lines, and text. +Items may be manipulated (e.g. moved or re-colored) and +L<callbacks|Tk::callbacks> may +be associated with items in much the same way that the L<bind|Tk::bind> +method allows callbacks to be bound to widgets. For example, +a particular callback may be associated with the B<E<lt>Button-1E<gt>> event +so that the callback is invoked whenever button 1 is pressed with +the mouse cursor over an item. +This means that items in a canvas can have behaviors defined by +the Callbacks bound to them. + +=head1 DISPLAY LIST + +The items in a canvas are ordered for purposes of display, +with the first item in the display list being displayed +first, followed by the next item in the list, and so on. +Items later in the display list obscure those that are +earlier in the display list and are sometimes referred to +as being I<``on top''> of earlier items. +When a new item is created it is placed at the end of the +display list, on top of everything else. +Widget methods may be used to re-arrange the order of the +display list. + +Window items are an exception to the above rules. The underlying +window systems require them always to be drawn on top of other items. +In addition, the stacking order of window items +is not affected by any of the canvas methods; you must use +the L<raise|Tk::Widget> and L<lower|Tk::Widget> Tk widget methods instead. + +=head1 ITEM IDS AND TAGS + +Items in a canvas widget may be named in either of two ways: +by id or by tag. +Each item has a unique identifying number which is assigned to +that item when it is created. The id of an item never changes +and id numbers are never re-used within the lifetime of a +canvas widget. + +Each item may also have any number of I<tags> associated +with it. A tag is just a string of characters, and it may +take any form except that of an integer. +For example, ``x123'' is OK but ``123'' isn't. +The same tag may be associated with many different items. +This is commonly done to group items in various interesting +ways; for example, all selected items might be given the +tag ``selected''. + +The tag B<all> is implicitly associated with every item +in the canvas; it may be used to invoke operations on +all the items in the canvas. + +The tag B<current> is managed automatically by Tk; +it applies to the I<current item>, which is the +topmost item whose drawn area covers the position of +the mouse cursor. +If the mouse is not in the canvas widget or is not over +an item, then no item has the B<current> tag. + +When specifying items in canvas methods, if the +specifier is an integer then it is assumed to refer to +the single item with that id. +If the specifier is not an integer, then it is assumed to +refer to all of the items in the canvas that have a tag +matching the specifier. +The symbol I<tagOrId> is used below to indicate that +an argument specifies either an id that selects a single +item or a tag that selects zero or more items. + +I<tagOrId> may contain a logical expressions of +tags by using operators: 'E<amp>E<amp>', '||', '^' '!', and parenthezised +subexpressions. For example: + +$c-E<gt>find('withtag', '(aE<amp>E<amp>!b)|(!aE<amp>E<amp>b)'); + +or equivalently: + +$c-E<gt>find('withtag', 'a^b'); + +will find only those items with either "a" or "b" tags, but not both. + +Some methods only operate on a single item at a +time; if I<tagOrId> is specified in a way that +names multiple items, then the normal behavior is for +the methods is to use the first (lowest) of these items in +the display list that is suitable for the method. +Exceptions are noted in the method descriptions +below. + +=head1 COORDINATES + +All coordinates related to canvases are stored as floating-point +numbers. +Coordinates and distances are specified in screen units, +which are floating-point numbers optionally followed +by one of several letters. +If no letter is supplied then the distance is in pixels. +If the letter is B<m> then the distance is in millimeters on +the screen; if it is B<c> then the distance is in centimeters; +B<i> means inches, and B<p> means printers points (1/72 inch). +Larger y-coordinates refer to points lower on the screen; larger +x-coordinates refer to points farther to the right. + +=head1 TRANSFORMATIONS + +Normally the origin of the canvas coordinate system is at the +upper-left corner of the window containing the canvas. +It is possible to adjust the origin of the canvas +coordinate system relative to the origin of the window using the +B<xview> and B<yview> methods; this is typically used +for scrolling. +Canvases do not support scaling or rotation of the canvas coordinate +system relative to the window coordinate system. + +Individual items may be moved or scaled using methods +described below, but they may not be rotated. + +=head1 INDICES + +Text items support the notion of an I<index> for identifying +particular positions within the item. + +Indices are used for methods such as inserting text, deleting +a range of characters, and setting the insertion cursor position. +An index may be specified in any of a number of ways, and +different types of items may support different forms for +specifying indices. + +In a similar fashion, line and polygon items support I<index> for +identifying, inserting and deleting subsets of their coordinates. +Indices are used for commands such as inserting or deleting +a range of characters or coordinates, and setting the insertion +cursor position. An index may be specified in any of a number +of ways, and different types of items may support different forms +for specifying indices. + +Text items support the following forms for an index; if you +define new types of text-like items, it would be advisable to +support as many of these forms as practical. +Note that it is possible to refer to the character just after +the last one in the text item; this is necessary for such +tasks as inserting new text at the end of the item. +Lines and Polygons don't support the insertion cursor +and the selection. Their indices are supposed to be even +always, because coordinates always appear in pairs. + +=over 4 + +=item I<number> + +A decimal number giving the position of the desired character +within the text item. +0 refers to the first character, 1 to the next character, and +so on. If indexes are odd for lines and polygons, they will be +automatically decremented by one. +A number less than 0 is treated as if it were zero, and a +number greater than the length of the text item is treated +as if it were equal to the length of the text item. For +polygons, numbers less than 0 or greater then the length +of the coordinate list will be adjusted by adding or substracting +the length until the result is between zero and the length, +inclusive. + +=item B<end> + +Refers to the character or coordinate just after the last one +in the item (same as the number of characters or coordinates +in the item). + +=item B<insert> + +Refers to the character just before which the insertion cursor +is drawn in this item. Not valid for lines and polygons. + +=item B<sel.first> + +Refers to the first selected character in the item. +If the selection isn't in this item then this form is illegal. + +=item B<sel.last> + +Refers to the last selected character in the item. +If the selection isn't in this item then this form is illegal. + +=item B<[>I<x,y>B<]> + +Refers to the character or coordinate at the point given by I<x> and +I<y>, where I<x> and I<y> are specified in the coordinate +system of the canvas. +If I<x> and I<y> lie outside the coordinates covered by the +text item, then they refer to the first or last character in the +line that is closest to the given point. +The Tcl string form "@x,y" is also allowed. + +=back + +=head1 DASH PATTERNS + +Many items support the notion of an dash pattern for outlines. + +The first possible syntax is a list of integers. Each element +represents the number of pixels of a line segment. Only the odd +segments are drawn using the "outline" color. The other segments +are drawn transparent. + +The second possible syntax is a character list containing only +5 possible characters B<[.,-_ ]>, with the first 4 characters +producing a segment of length 1 to 4, respectively, followed +by a transparent segment of length 2. The space can be used +repeatedly to enlarge the space between other line elements +by 1, and can not occur as the first position in the string. +The main difference of this syntax with the previous one is +that it it shape-conserving. This means that all values in the dash +list will be multiplied by the line width before display. This +assures that "." will always be displayed as a dot and "-" +always as a dash regardless of the line width. + +Some examples, for a line width of 2: + + -dash . = -dash [2,4] + -dash - = -dash [6,4] + -dash -. = -dash [6,4,2,4] + -dash -.. = -dash [6,4,2,4,2,4] + -dash '. ' = -dash [2,8] + -dash ',' = -dash [4,4] + +On systems where only a limited set of dash patterns is available, +the dash pattern will be displayed as the closest available dash +pattern. For example, on Windows only the first 4 of the +above examples are available. The last 2 examples will be +displayed identically as the first one. + +=head1 WIDGET METHODS + +The B<Canvas> method creates a widget object. +This object supports the B<configure> and B<cget> methods +described in L<Tk::options> which can be used to enquire and +modify the options described above. +The widget also inherits all the methods provided by the generic +L<Tk::Widget|Tk::Widget> class. + +The following additional methods are available for canvas widgets: + +=over 4 + +=item I<$canvas>-E<gt>B<addtag>(I<tag, searchSpec, >?I<arg, arg, ...>?) + +For each item that meets the constraints specified by +I<searchSpec> and the I<arg>s, add +I<tag> to the list of tags associated with the item if it +isn't already present on that list. +It is possible that no items will satisfy the constraints +given by I<searchSpec> and I<arg>s, in which case the +method has no effect. +This command returns an empty string as result. +I<SearchSpec> and I<arg>'s may take any of the following +forms: + +=over 8 + +=item B<above >I<tagOrId> + +Selects the item just after (above) the one given by I<tagOrId> +in the display list. +If I<tagOrId> denotes more than one item, then the last (topmost) +of these items in the display list is used. + +=item B<all> + +Selects all the items in the canvas. + +=item B<below >I<tagOrId> + +Selects the item just before (below) the one given by I<tagOrId> +in the display list. +If I<tagOrId> denotes more than one item, then the first (lowest) +of these items in the display list is used. + +=item B<closest >I<x y >?I<halo>? ?I<start>? + +Selects the item closest to the point given by I<x> and I<y>. +If more than one item is at the same closest distance (e.g. two +items overlap the point), then the top-most of these items (the +last one in the display list) is used. +If I<halo> is specified, then it must be a non-negative +value. +Any item closer than I<halo> to the point is considered to +overlap it. +The I<start> argument may be used to step circularly through +all the closest items. +If I<start> is specified, it names an item using a tag or id +(if by tag, it selects the first item in the display list with +the given tag). +Instead of selecting the topmost closest item, this form will +select the topmost closest item that is below I<start> in +the display list; if no such item exists, then the selection +behaves as if the I<start> argument had not been specified. + +=item B<enclosed> I<x1> I<y1> I<x2> I<y2> + +Selects all the items completely enclosed within the rectangular +region given by I<x1>, I<y1>, I<x2>, and I<y2>. +I<X1> must be no greater then I<x2> and I<y1> must be +no greater than I<y2>. + +=item B<overlapping> I<x1> I<y1> I<x2> I<y2> + +Selects all the items that overlap or are enclosed within the +rectangular region given by I<x1>, I<y1>, I<x2>, +and I<y2>. +I<X1> must be no greater then I<x2> and I<y1> must be +no greater than I<y2>. + +=item B<withtag >I<tagOrId> + +Selects all the items given by I<tagOrId>. + +=back + +=item I<$canvas>-E<gt>B<bbox>(I<tagOrId, >?I<tagOrId, tagOrId, ...>?) + +Returns a list with four elements giving an approximate bounding box +for all the items named by the I<tagOrId> arguments. +The list has the form ``I<x1 y1 x2 y2>'' such that the drawn +areas of all the named elements are within the region bounded by +I<x1> on the left, I<x2> on the right, I<y1> on the top, +and I<y2> on the bottom. +The return value may overestimate the actual bounding box by +a few pixels. +If no items match any of the I<tagOrId> arguments or if the +matching items have empty bounding boxes (i.e. they have nothing +to display) +then an empty string is returned. + +=item I<$canvas>-E<gt>B<bind>(I<tagOrId>?, I<sequence>? ?,I<callback>?) + +This method associates I<callback> with all the items given by +I<tagOrId> such that whenever the event sequence given by +I<sequence> occurs for one of the items the callback will +be invoked. +This method is similar to the B<bind> method except that +it operates on items in a canvas rather than entire widgets. +See L<Tk::bind> for complete details +on the syntax of I<sequence> and the substitutions performed +on I<callback> before invoking it. +If all arguments are specified then a new binding is created, replacing +any existing binding for the same I<sequence> and I<tagOrId> +(if the first character of I<command> is ``+'' then I<command> +augments an existing binding rather than replacing it). +In this case the return value is an empty string. +If I<callback> is omitted then the method returns the I<callback> +associated with I<tagOrId> and I<sequence> (an error occurs +if there is no such binding). +If both I<callback> and I<sequence> are omitted then the method +returns a list of all the sequences for which bindings have been +defined for I<tagOrId>. + +=over 8 + +The only events for which bindings may be specified are those related to +the mouse and keyboard (such as B<Enter>, B<Leave>, +B<ButtonPress>, B<Motion>, and B<KeyPress>) or virtual events. +The handling of events in canvases uses the current item defined +in L<"ITEM IDS AND TAGS"> above. B<Enter> and B<Leave> events trigger for an +item when it becomes the current item or ceases to be the current item; +note that these events are different than B<Enter> and B<Leave> +events for windows. Mouse-related events are directed to the current +item, if any. Keyboard-related events are directed to the focus item, if +any (see the L<focus|/focus> method below for more on this). If a +virtual event is used in a binding, that binding can trigger only if the +virtual event is defined by an underlying mouse-related or +keyboard-related event. + +It is possible for multiple bindings to match a particular event. +This could occur, for example, if one binding is associated with the +item's id and another is associated with one of the item's tags. +When this occurs, all of the matching bindings are invoked. +A binding associated with the B<all> tag is invoked first, +followed by one binding for each of the item's tags (in order), +followed by a binding associated with the item's id. +If there are multiple matching bindings for a single tag, +then only the most specific binding is invoked. +A B<continue> in a callback terminates that +subroutine, and a B<break> method terminates that subroutine +and skips any remaining callbacks for the event, just as for the +B<bind> method. + +If bindings have been created for a canvas window using the B<CanvasBind> +method, then they are invoked in addition to bindings created for +the canvas's items using the B<bind> method. +The bindings for items will be invoked before any of the bindings +for the window as a whole. + +=back + +=item I<$canvas>-E<gt>B<canvasx>(I<screenx>?, I<gridspacing>?) + +Given a window x-coordinate in the canvas I<screenx>, this method returns +the canvas x-coordinate that is displayed at that location. +If I<gridspacing> is specified, then the canvas coordinate is +rounded to the nearest multiple of I<gridspacing> units. + +=item I<$canvas>-E<gt>B<canvasy>(I<screeny, >?I<gridspacing>?) + +Given a window y-coordinate in the canvas I<screeny> this method returns +the canvas y-coordinate that is displayed at that location. +If I<gridspacing> is specified, then the canvas coordinate is +rounded to the nearest multiple of I<gridspacing> units. + +=item I<$canvas>-E<gt>B<coords>(I<tagOrId >?I<x0,y0 ...>?) + +Query or modify the coordinates that define an item. +If no coordinates are specified, this method returns a list +whose elements are the coordinates of the item named by +I<tagOrId>. +If coordinates are specified, then they replace the current +coordinates for the named item. +If I<tagOrId> refers to multiple items, then +the first one in the display list is used. + +=item I<$canvas>-E<gt>B<create>(I<type, x, y, >?I<x, y, ...>?, ?I<option, value, ...>?) + +Create a new item in I<$canvas> of type I<type>. +The exact format of the arguments after B<type> depends +on B<type>, but usually they consist of the coordinates for +one or more points, followed by specifications for zero or +more item options. +See the subsections on individual item types below for more +on the syntax of this method. +This method returns the id for the new item. + +=item I<$canvas>-E<gt>B<dchars>(I<tagOrId, first, >?I<last>?) + +For each item given by I<tagOrId>, delete the characters, or coordinates, +in the range given by I<first> and I<last>, inclusive. +If some of the items given by I<tagOrId> don't support +Text items interpret I<first> and I<last> as indices to a character, +line and polygon items interpret them indices to a coordinate (an x,y pair). +within the item(s) as described in L<"INDICES"> above. +If I<last> is omitted, it defaults to I<first>. +This method returns an empty string. + +=item I<$canvas>-E<gt>B<delete>(?I<tagOrId, tagOrId, ...>?) + +Delete each of the items given by each I<tagOrId>, and return +an empty string. + +=item I<$canvas>-E<gt>B<dtag>(I<tagOrId, >?I<tagToDelete>?) + +For each of the items given by I<tagOrId>, delete the +tag given by I<tagToDelete> from the list of those +associated with the item. +If an item doesn't have the tag I<tagToDelete> then +the item is unaffected by the method. +If I<tagToDelete> is omitted then it defaults to I<tagOrId>. +This method returns an empty string. + +=item I<$canvas>-E<gt>B<find>(I<searchCommand, >?I<arg, arg, ...>?) + +This method returns a list consisting of all the items that +meet the constraints specified by I<searchCommand> and +I<arg>'s. +I<SearchCommand> and I<args> have any of the forms +accepted by the B<addtag> method. +The items are returned in stacking order, with the lowest item first. + +=item focus + +=item I<$canvas>-E<gt>B<focus>(?I<tagOrId>?) + +Set the keyboard focus for the canvas widget to the item given by +I<tagOrId>. +If I<tagOrId> refers to several items, then the focus is set +to the first such item in the display list that supports the +insertion cursor. +If I<tagOrId> doesn't refer to any items, or if none of them +support the insertion cursor, then the focus isn't changed. +If I<tagOrId> is an empty +string, then the focus item is reset so that no item has the focus. +If I<tagOrId> is not specified then the method returns the +id for the item that currently has the focus, or an empty string +if no item has the focus. + +=over 8 + +Once the focus has been set to an item, the item will display +the insertion cursor and all keyboard events will be directed +to that item. +The focus item within a canvas and the focus window on the +screen (set with the B<focus> method) are totally independent: +a given item doesn't actually have the input focus unless (a) +its canvas is the focus window and (b) the item is the focus item +within the canvas. +In most cases it is advisable to follow the B<focus> widget +method with the B<CanvasFocus> method to set the focus window to +the canvas (if it wasn't there already). + +=back + +=item I<$canvas>-E<gt>B<gettags>(I<tagOrId>) + +Return a list whose elements are the tags associated with the +item given by I<tagOrId>. +If I<tagOrId> refers to more than one item, then the tags +are returned from the first such item in the display list. +If I<tagOrId> doesn't refer to any items, or if the item +contains no tags, then an empty string is returned. + +=item I<$canvas>-E<gt>B<icursor>(I<tagOrId, index>) + +Set the position of the insertion cursor for the item(s) given by I<tagOrId> +to just before the character whose position is given by I<index>. +If some or all of the items given by I<tagOrId> don't support +an insertion cursor then this method has no effect on them. +See L<"INDICES"> above for a description of the +legal forms for I<index>. +Note: the insertion cursor is only displayed in an item if +that item currently has the keyboard focus (see the widget +method B<focus>, below), but the cursor position may +be set even when the item doesn't have the focus. +This method returns an empty string. + +=item I<$canvas>-E<gt>B<index>(I<tagOrId, index>) + +This method returns a decimal string giving the numerical index +within I<tagOrId> corresponding to I<index>. +I<Index> gives a textual description of the desired position +as described in L<"INDICES"> above. +Text items interpret I<index> as an index to a character, +line and polygon items interpret it as an index to a coordinate (an x,y pair). +The return value is guaranteed to lie between 0 and the number +of characters, or coordinates, within the item, inclusive. +If I<tagOrId> refers to multiple items, then the index +is processed in the first of these items that supports indexing +operations (in display list order). + +=item I<$canvas>-E<gt>B<insert>(I<tagOrId, beforeThis, string>) + +For each of the items given by I<tagOrId>, if the item supports +text or coordinate, insertion then I<string> is inserted into the item's +text just before the character, or coordinate, whose index is I<beforeThis>. +Text items interpret I<beforethis> as an index to a character, +line and polygon items interpret it as an index to a coordinate (an x,y pair). +For lines and polygons the I<string> must be a valid coordinate +sequence. +See L<"INDICES"> above for information about the forms allowed +for I<beforeThis>. +This method returns an empty string. + +=item I<$canvas>-E<gt>B<itemcget>(I<tagOrId, >I<option>) + +Returns the current value of the configuration option for the +item given by I<tagOrId> whose name is I<option>. +This method is similar to the L<cget|Tk::option> method except that +it applies to a particular item rather than the widget as a whole. +I<Option> may have any of the values accepted by the B<create> +method when the item was created. +If I<tagOrId> is a tag that refers to more than one item, +the first (lowest) such item is used. + +=item I<$canvas>-E<gt>B<itemconfigure>(I<tagOrId, >?I<option>?, ?I<value>?, ?I<option, value, ...>?) + +This method is similar to the L<configure|Tk::option> method except +that it modifies item-specific options for the items given by +I<tagOrId> instead of modifying options for the overall +canvas widget. +If no I<option> is specified, returns a list describing all of +the available options for the first item given by I<tagOrId> +(see L<Tk::options> for +information on the format of this list). If I<option> is specified +with no I<value>, then the method returns a list describing the +one named option (this list will be identical to the corresponding +sublist of the value returned if no I<option> is specified). If +one or more I<option-value> pairs are specified, then the method +modifies the given widget option(s) to have the given value(s) in +each of the items given by I<tagOrId>; in +this case the method returns an empty string. +The I<option>s and I<value>s are the same as those permissible +in the B<create> method when the item(s) were created; +see the sections describing individual item types below for details +on the legal options. + +=item I<$canvas>-E<gt>B<lower>(I<tagOrId, >?I<belowThis>?) + +Move all of the items given by I<tagOrId> to a new position +in the display list just before the item given by I<belowThis>. +If I<tagOrId> refers to more than one item then all are moved +but the relative order of the moved items will not be changed. +I<BelowThis> is a tag or id; if it refers to more than one +item then the first (lowest) of these items in the display list is used +as the destination location for the moved items. +Note: this method has no effect on window items. Window items always +obscure other item types, and the stacking order of window items is +determined by the B<raise> and B<lower> methods of the widget, not the +B<raise> and B<lower> methods for canvases. +This method returns an empty string. + +=item I<$canvas>-E<gt>B<move>(I<tagOrId, xAmount, yAmount>) + +Move each of the items given by I<tagOrId> in the canvas coordinate +space by adding I<xAmount> to the x-coordinate of each point +associated with the item and I<yAmount> to the y-coordinate of +each point associated with the item. +This method returns an empty string. + +=item I<$canvas>-E<gt>B<postscript>(?I<option, value, option, value, ...>?) + +Generate a Postscript representation for part or all of the canvas. +If the B<-file> option is specified then the Postscript is written +to a file and an empty string is returned; otherwise the Postscript +is returned as the result of the method. +If the interpreter that owns the canvas is marked as safe, the operation +will fail because safe interpreters are not allowed to write files. +If the B<-channel> option is specified, the argument denotes the name +of a channel already opened for writing. The Postscript is written to +that channel, and the channel is left open for further writing at the end +of the operation. +The Postscript is created in Encapsulated Postscript form using +version 3.0 of the Document Structuring Conventions. +Note: by default Postscript is only generated for information that +appears in the canvas's window on the screen. If the canvas is +freshly created it may still have its initial size of 1x1 pixel +so nothing will appear in the Postscript. To get around this problem +either invoke the B<update> method to wait for the canvas window +to reach its final size, or else use the B<-width> and B<-height> +options to specify the area of the canvas to print. +The I<option>-I<value> argument pairs provide additional +information to control the generation of Postscript. The following +options are supported: + +=over 8 + +=item B<-colormap> =E<gt> I<hashRef> + +I<HashRef> must be a reference to a hash variable or an anonymous hash +that specifies a color mapping to use in the Postscript. +Each value of the hash must consist of Postscript +code to set a particular color value (e.g. ``B<1.0 1.0 0.0 setrgbcolor>''). +When outputting color information in the Postscript, Tk checks +to see if there is a key in the hash with the same +name as the color. +If so, Tk uses the value of the element as the Postscript method +to set the color. +If this option hasn't been specified, or if there isn't a key +in I<hashRef> for a given color, then Tk uses the red, green, +and blue intensities from the X color. + +=item B<-colormode> =E<gt> I<mode> + +Specifies how to output color information. I<Mode> must be either +B<color> (for full color output), B<gray> (convert all colors +to their gray-scale equivalents) or B<mono> (convert all colors +to black or white). + +=item B<-file> =E<gt> I<fileName> + +Specifies the name of the file in which to write the Postscript. +If this option isn't specified then the Postscript is returned as the +result of the method instead of being written to a file. + +=item B<-fontmap> =E<gt> I<hashRef> + +I<HashRef> must be a reference to a hash variable or an anonymous hash +that specifies a font mapping to use in the Postscript. +Each value of the hash must consist of an array reference with +two elements, which are the name and point size of a Postscript font. +When outputting Postscript commands for a particular font, Tk +checks to see if I<hashRef> contains a value with the same +name as the font. +If there is such an element, then the font information contained in +that element is used in the Postscript. +Otherwise Tk attempts to guess what Postscript font to use. +Tk's guesses generally only work for well-known fonts such as +Times and Helvetica and Courier, and only if the X font name does not +omit any dashes up through the point size. +For example, B<-*-Courier-Bold-R-Normal--*-120-*> will work but +B<*Courier-Bold-R-Normal*120*> will not; Tk needs the dashes to +parse the font name). + +=item B<-height> =E<gt> I<size> + +Specifies the height of the area of the canvas to print. +Defaults to the height of the canvas window. + +=item B<-pageanchor> =E<gt> I<anchor> + +Specifies which point of the printed area of the canvas should appear over +the positioning point on the page (which is given by the B<-pagex> +and B<-pagey> options). +For example, B<-pageanchor>=>B<n> means that the top center of the +area of the canvas being printed (as it appears in the canvas window) +should be over the positioning point. Defaults to B<center>. + +=item B<-pageheight> =E<gt> I<size> + +Specifies that the Postscript should be scaled in both x and y so +that the printed area is I<size> high on the Postscript page. +I<Size> consists of a floating-point number followed by +B<c> for centimeters, B<i> for inches, B<m> for millimeters, +or B<p> or nothing for printer's points (1/72 inch). +Defaults to the height of the printed area on the screen. +If both B<-pageheight> and B<-pagewidth> are specified then +the scale factor from B<-pagewidth> is used (non-uniform scaling +is not implemented). + +=item B<-pagewidth> =E<gt> I<size> + +Specifies that the Postscript should be scaled in both x and y so +that the printed area is I<size> wide on the Postscript page. +I<Size> has the same form as for B<-pageheight>. +Defaults to the width of the printed area on the screen. +If both B<-pageheight> and B<-pagewidth> are specified then +the scale factor from B<-pagewidth> is used (non-uniform scaling +is not implemented). + +=item B<-pagex> =E<gt> I<position> + +I<Position> gives the x-coordinate of the positioning point on +the Postscript page, using any of the forms allowed for B<-pageheight>. +Used in conjunction with the B<-pagey> and B<-pageanchor> options +to determine where the printed area appears on the Postscript page. +Defaults to the center of the page. + +=item B<-pagey> =E<gt> I<position> + +I<Position> gives the y-coordinate of the positioning point on +the Postscript page, using any of the forms allowed for B<-pageheight>. +Used in conjunction with the B<-pagex> and B<-pageanchor> options +to determine where the printed area appears on the Postscript page. +Defaults to the center of the page. + +=item B<-rotate> =E<gt> I<boolean> + +I<Boolean> specifies whether the printed area is to be rotated 90 +degrees. +In non-rotated output the x-axis of the printed area runs along +the short dimension of the page (``portrait'' orientation); +in rotated output the x-axis runs along the long dimension of the +page (``landscape'' orientation). +Defaults to non-rotated. + +=item B<-width> =E<gt> I<size> + +Specifies the width of the area of the canvas to print. +Defaults to the width of the canvas window. + +=item B<-x> => I<position> + +Specifies the x-coordinate of the left edge of the area of the +canvas that is to be printed, in canvas coordinates, not window +coordinates. +Defaults to the coordinate of the left edge of the window. + +=item B<-y> => I<position> + +Specifies the y-coordinate of the top edge of the area of the +canvas that is to be printed, in canvas coordinates, not window +coordinates. +Defaults to the coordinate of the top edge of the window. + +=back + +=item I<$canvas>-E<gt>B<raise>(I<tagOrId, >?I<aboveThis>?) + +Move all of the items given by I<tagOrId> to a new position +in the display list just after the item given by I<aboveThis>. +If I<tagOrId> refers to more than one item then all are moved +but the relative order of the moved items will not be changed. +I<AboveThis> is a tag or id; if it refers to more than one +item then the last (topmost) of these items in the display list is used +as the destination location for the moved items. +Note: this method has no effect on window items. Window items always +obscure other item types, and the stacking order of window items is +determined by the B<raise> and B<lower> widget commands, not the +B<raise> and B<lower> methods for canvases. +This method returns an empty string. + +=item I<$canvas>-E<gt>B<scale>(I<tagOrId, xOrigin, yOrigin, xScale, yScale>) + +Rescale all of the items given by I<tagOrId> in canvas coordinate +space. +I<XOrigin> and I<yOrigin> identify the origin for the scaling +operation and I<xScale> and I<yScale> identify the scale +factors for x- and y-coordinates, respectively (a scale factor of +1.0 implies no change to that coordinate). +For each of the points defining each item, the x-coordinate is +adjusted to change the distance from I<xOrigin> by a factor +of I<xScale>. +Similarly, each y-coordinate is adjusted to change the distance +from I<yOrigin> by a factor of I<yScale>. +This method returns an empty string. + +=item I<$canvas>-E<gt>B<scan>(I<option, args>) + +This method is used to implement scanning on canvases. It has +two forms, depending on I<option>: + +=over 8 + +=item I<$canvas>-E<gt>B<scanMark>(I<x, y>) + +Records I<x> and I<y> and the canvas's current view; used +in conjunction with later B<scanDragto> method. +Typically this method is associated with a mouse button press in +the widget and I<x> and I<y> are the coordinates of the +mouse. It returns an empty string. + +=item I<$canvas>-E<gt>B<scanDragto>(I<x, y, ?gain?>.) + +This method computes the difference between its I<x> and I<y> +arguments (which are typically mouse coordinates) and the I<x> and +I<y> arguments to the last B<scanMark> method for the widget. +It then adjusts the view by 10 times the +difference in coordinates. This method is typically associated +It then adjusts the view by I<gain> times the +difference in coordinates, where I<gain> defaults to 10. +This command is typically associated +with mouse motion events in the widget, to produce the effect of +dragging the canvas at high speed through its window. The return +value is an empty string. + +=back + +=item I<$canvas>-E<gt>B<select>(I<option, >?I<tagOrId, arg>?) + +Manipulates the selection in one of several ways, depending on +I<option>. +The method may take any of the forms described below. +In all of the descriptions below, I<tagOrId> must refer to +an item that supports indexing and selection; if it refers to +multiple items then the first of +these that supports indexing and the selection is used. +I<Index> gives a textual description of a position +within I<tagOrId>, as described in L<"INDICES"> above. + +=over 8 + +=item I<$canvas>-E<gt>B<selectAdjust>(I<tagOrId, index>) + +Locate the end of the selection in I<tagOrId> nearest +to the character given by I<index>, and adjust that +end of the selection to be at I<index> (i.e. including +but not going beyond I<index>). +The other end of the selection is made the anchor point +for future B<selectTo> method calls. +If the selection isn't currently in I<tagOrId> then +this method behaves the same as the B<selectTo> widget +method. +Returns an empty string. + +=item I<$canvas>-E<gt>B<selectClear> + +Clear the selection if it is in this widget. +If the selection isn't in this widget then the method +has no effect. +Returns an empty string. + +=item I<$canvas>-E<gt>B<selectFrom>(I<tagOrId, index>) + +Set the selection anchor point for the widget to be just +before the character +given by I<index> in the item given by I<tagOrId>. +This method doesn't change the selection; it just sets +the fixed end of the selection for future B<selectTo> +method calls. +Returns an empty string. + +=item I<$canvas>-E<gt>B<selectItem> + +Returns the id of the selected item, if the selection is in an +item in this canvas. +If the selection is not in this canvas then an empty string +is returned. + +=item I<$canvas>-E<gt>B<selectTo>(I<tagOrId, index>) + +Set the selection to consist of those characters of I<tagOrId> +between the selection anchor point and +I<index>. +The new selection will include the character given by I<index>; +it will include the character given by the anchor point only if +I<index> is greater than or equal to the anchor point. +The anchor point is determined by the most recent B<selectAdjust> +or B<selectFrom> method calls for this widget. +If the selection anchor point for the widget isn't currently in +I<tagOrId>, then it is set to the same character given +by I<index>. +Returns an empty string. + +=back + +=item I<$canvas>-E<gt>B<type>(I<tagOrId>) + +Returns the type of the item given by I<tagOrId>, such as +B<rectangle> or B<text>. +If I<tagOrId> refers to more than one item, then the type +of the first item in the display list is returned. +If I<tagOrId> doesn't refer to any items at all then +an empty string is returned. + +=item I<$canvas>-E<gt>B<xview>(?I<args>?) + +This method is used to query and change the horizontal position of the +information displayed in the canvas's window. +It can take any of the following forms: + +=over 8 + +=item I<$canvas>-E<gt>B<xview> + +Returns a list containing two elements. +Each element is a real fraction between 0 and 1; together they describe +the horizontal span that is visible in the window. +For example, if the first element is .2 and the second element is .6, +20% of the canvas's area (as defined by the B<-scrollregion> option) +is off-screen to the left, the middle 40% is visible +in the window, and 40% of the canvas is off-screen to the right. +These are the same values passed to scrollbars via the B<-xscrollcommand> +option. + +=item I<$canvas>-E<gt>B<xviewMoveto>(I<fraction>) + +Adjusts the view in the window so that I<fraction> of the +total width of the canvas is off-screen to the left. +I<Fraction> must be a fraction between 0 and 1. + +=item I<$canvas>-E<gt>B<xviewScroll>(I<number, what>) + +This method shifts the view in the window left or right according to +I<number> and I<what>. +I<Number> must be an integer. +I<What> must be either B<units> or B<pages> or an abbreviation +of one of these. +If I<what> is B<units>, the view adjusts left or right in units +of the B<xScrollIncrement> option, if it is greater than zero, +or in units of one-tenth the window's width otherwise. +If I<what is >B<pages> then the view +adjusts in units of nine-tenths the window's width. +If I<number> is negative then information farther to the left +becomes visible; if it is positive then information farther to the right +becomes visible. + +=back + +=item I<$canvas>-E<gt>B<yview>(I<?args>?) + +This method is used to query and change the vertical position of the +information displayed in the canvas's window. +It can take any of the following forms: + +=over 8 + +=item I<$canvas>-E<gt>B<yview> + +Returns a list containing two elements. +Each element is a real fraction between 0 and 1; together they describe +the vertical span that is visible in the window. +For example, if the first element is .6 and the second element is 1.0, +the lowest 40% of the canvas's area (as defined by the B<-scrollregion> +option) is visible in the window. +These are the same values passed to scrollbars via the B<-yscrollcommand> +option. + +=item I<$canvas>-E<gt>B<yviewMoveto>(I<fraction>) + +Adjusts the view in the window so that I<fraction> of the canvas's +area is off-screen to the top. +I<Fraction> is a fraction between 0 and 1. + +=item I<$canvas>-E<gt>B<yviewScroll>(I<number, what>) + +This method adjusts the view in the window up or down according to +I<number> and I<what>. +I<Number> must be an integer. +I<What> must be either B<units> or B<pages>. +If I<what> is B<units>, the view adjusts up or down in units +of the B<yScrollIncrement> option, if it is greater than zero, +or in units of one-tenth the window's height otherwise. +If I<what> is B<pages> then +the view adjusts in units of nine-tenths the window's height. +If I<number> is negative then higher information becomes +visible; if it is positive then lower information +becomes visible. + +=back + +=back + +=head1 OVERVIEW OF ITEM TYPES + +The sections below describe the various types of items supported +by canvas widgets. Each item type is characterized by two things: +first, the form of the B<create> method used to create +instances of the type; and second, a set of configuration options +for items of that type, which may be used in the +B<create> and B<itemconfigure> methods. +Most items don't support indexing or selection or the methods +related to them, such as B<index> and B<insert>. +Where items do support these facilities, it is noted explicitly +in the descriptions below. +At present, text, line and polygon items provide this support. +For lines and polygons the indexing facility is used to manipulate +the coordinates of the item. + +=head1 ARC ITEMS + +Items of type B<arc> appear on the display as arc-shaped regions. +An arc is a section of an oval delimited by two angles (specified +by the B<-start> and B<-extent> options) and displayed in +one of several ways (specified by the B<-style> option). +Arcs are created with methods of the following form: + + $canvas->createArc(x1, y1, x2, y2, ?option, value, option, value, ...?) + +The arguments I<x1>, I<y1>, I<x2>, and I<y2> give +the coordinates of two diagonally opposite corners of a +rectangular region enclosing the oval that defines the arc. +After the coordinates there may be any number of I<option>-I<value> +pairs, each of which sets one of the configuration options +for the item. These same I<option>-I<value> pairs may be +used in B<itemconfigure> methods to change the item's +configuration. +The following options are supported for arcs: + +=over 4 + +=item B<-dash> =E<gt> I<pattern> + +=item B<-activedash> =E<gt> I<pattern> + +=item B<-disableddash> =E<gt> I<pattern> + +This option specifies dash patterns for the normal state, the active +state, and the disabled state of an arc item. +I<pattern> may have any of the forms accepted by B<Tk_GetDash>. +If the dash options are omitted then the default is a solid outline. + +=item B<-dashoffset> =E<gt> I<offset> + +The starting I<offset> into the pattern provided by the +B<-dash> option. +B<-dashoffset> is ignored if there is no B<-dash> pattern. + +=item B<-extent> =E<gt> I<degrees> + +Specifies the size of the angular range occupied by the arc. +The arc's range extends for I<degrees> degrees counter-clockwise +from the starting angle given by the B<-start> option. +I<Degrees> may be negative. +If it is greater than 360 or less than -360, then I<degrees> +modulo 360 is used as the extent. + +=item B<-fill> =E<gt> I<color> + +=item B<-activefill> =E<gt> I<color> + +=item B<-disabledfill> =E<gt> I<color> + +Specifies the color to be used to fill the arc region in its normal, active, and +disabled states, +I<Color> may have any of the forms accepted by B<Tk_GetColor>. +If I<color> is an empty string (the default), then +then the arc will not be filled. + +=item B<-outline> =E<gt> I<color> + +=item B<-activeoutline> =E<gt> I<color> + +=item B<-disabledoutline> =E<gt> I<color> + +This option specifies the color that should be used to draw the +outline of the arc in its normal, active and disabled states. +I<Color> may have any of the forms accepted by B<Tk_GetColor>. +This option defaults to B<black>. If I<color> is specified +as undef then no outline is drawn for the arc. + +=item B<-outlinestipple> =E<gt> I<bitmap> + +=item B<-activeoutlinestipple> =E<gt> I<bitmap> + +=item B<-disabledoutlinestipple> =E<gt> I<bitmap> + +This option specifies stipple patterns that should be used to draw the +outline of the arc in its normal, active and disabled states. +Indicates that the outline for the arc should be drawn with a stipple pattern; +I<bitmap> specifies the stipple pattern to use, in any of the +forms accepted by B<Tk_GetBitmap>. +If the B<-outline> option hasn't been specified then this option +has no effect. +If I<bitmap> is an empty string (the default), then the outline is drawn +in a solid fashion. + +=item B<-start> =E<gt> I<degrees> + +Specifies the beginning of the angular range occupied by the +arc. +I<Degrees> is given in units of degrees measured counter-clockwise +from the 3-o'clock position; it may be either positive or negative. + +=item B<-state> =E<gt> I<state> + +Modifies the state of the arc item where I<state> may be set to one of: +normal, disabled, hidden or "". If set to empty, the state of the canvas +itself is used. An arc item may also be in the "active" +state if the mouse is currently over it. Many options can take +separate specifications in normal, active and disabled states such that the +appearance of the item can be different in each state. + +=item B<-stipple> =E<gt> I<bitmap> + +=item B<-activestipple> =E<gt> I<bitmap> + +=item B<-disabledstipple> =E<gt> I<bitmap> + +This option specifies stipple patterns that should be used to fill the +the arc in its normal, active and disabled states. +I<bitmap> specifies the stipple pattern to use, in any of the +forms accepted by B<Tk_GetBitmap>. +If the B<-fill> option hasn't been specified then this option +has no effect. +If I<bitmap> is an empty string (the default), then filling is done +in a solid fashion. + +=item B<-style> =E<gt> I<type> + +Specifies how to draw the arc. If I<type> is B<pieslice> +(the default) then the arc's region is defined by a section +of the oval's perimeter plus two line segments, one between the center +of the oval and each end of the perimeter section. +If I<type> is B<chord> then the arc's region is defined +by a section of the oval's perimeter plus a single line segment +connecting the two end points of the perimeter section. +If I<type> is B<arc> then the arc's region consists of +a section of the perimeter alone. +In this last case the B<-fill> option is ignored. + +=item B<-tags> =E<gt> I<tagList> + +Specifies a set of tags to apply to the item. +I<TagList> consists of a list of tag names, which replace any +existing tags for the item. +I<TagList> may be an empty list. + +=item B<-updatecommand> =E<gt> I<command> + +Specifies a callback that is to be executed every time +the arc item is updated on the screen. + +=item B<-width> =E<gt> I<outlineWidth> + +=item B<-activewidth> =E<gt> I<outlineWidth> + +=item B<-disabledwidth> =E<gt> I<outlineWidth> + +Specifies the width of the outline to be drawn around +the arc's region, in its normal, active and disabled states. +I<outlineWidth> may be in any of the forms described in +the L<"COORDINATES"> section above. +If the B<-outline> option has been specified as undef +then this option has no effect. +Wide outlines will be drawn centered on the edges of the arc's region. +This option defaults to 1.0. + +=back + +=head1 BITMAP ITEMS + +Items of type B<bitmap> appear on the display as images with +two colors, foreground and background. +Bitmaps are created with methods of the following form: + + $canvas->createBitmap(x, y, ?option, value, option, value, ...?) + +The arguments I<x> and I<y> specify the coordinates of a +point used to position the bitmap on the display (see the B<-anchor> +option below for more information on how bitmaps are displayed). +After the coordinates there may be any number of I<option>-I<value> +pairs, each of which sets one of the configuration options +for the item. These same I<option>-I<value> pairs may be +used in B<itemconfigure> methods to change the item's +configuration. +The following options are supported for bitmaps: + +=over 4 + +=item B<-anchor> =E<gt> I<anchorPos> + +I<AnchorPos> tells how to position the bitmap relative to the +positioning point for the item; it may have any of the forms +accepted by B<Tk_GetAnchor>. For example, if I<anchorPos> +is B<center> then the bitmap is centered on the point; if +I<anchorPos> is B<n> then the bitmap will be drawn so that +its top center point is at the positioning point. +This option defaults to B<center>. + +=item B<-background> =E<gt> I<color> + +=item B<-activebackground> =E<gt> I<color> + +=item B<-disabledbackground> =E<gt> I<color> + +Specifies the color to use for each of the bitmap's '0' valued pixels +in its normal, active and disabled states. +I<Color> may have any of the forms accepted by B<Tk_GetColor>. +If this option isn't specified, or if it is specified as undef, +then nothing is displayed where the bitmap pixels are 0; this +produces a transparent effect. + +=item B<-bitmap> =E<gt> I<bitmap> + +=item B<-activebitmap> =E<gt> I<bitmap> + +=item B<-disabledbitmap> =E<gt> I<bitmap> + +Specifies the bitmaps to display in the item in its normal, active and +disabled states. All bitmaps must have the same width and height. +I<Bitmap> may have any of the forms accepted by B<Tk_GetBitmap>. + +=item B<-foreground> =E<gt> I<color> + +=item B<-activeforeground> =E<gt> I<color> + +=item B<-disabledforeground> =E<gt> I<color> + +Specifies the color to use for each of the bitmap's '1' valued pixels +in its normal, active and disabled states. +I<Color> may have any of the forms accepted by B<Tk_GetColor> and +defaults to B<black>. + +=item B<-state> =E<gt> I<state> + +Modifies the state of the bitmap item where I<state> may be set to one of: +normal, disabled, or hidden. An bitmap item may also be in the "active" +state if the mouse is currently over it. Many options can take +separate specifications in normal, active and disabled states such that the +appearance of the item can be different in each state. + +=item B<-tags> =E<gt> I<tagList> + +Specifies a set of tags to apply to the item. +I<TagList> consists of a list of tag names, which replace any +existing tags for the item. +I<TagList> may be an empty list. + +=item B<-updatecommand> =E<gt> I<command> + +Specifies a callback that is to be executed every time +the bitmap item is updated on the screen. + +=back + +=head1 GRID ITEMS + +Items of type B<grid> are intended for producing a visual reference for +interpreting other items. They can be drawn as either lines (with dash +style) or as rectangular "dots" at each grid point. + +Items of type B<grid> are unlike other items they always cover the +whole of the canvas, but are never enclosed by nor overlap any area +and are not near any point. That is they are intended to be always visible +but not "pickable", as such they do support the "active" state. +They are like other items in that: multiple +grids are permitted, they can be raised and lowered relative to other +items, they can be moved and scaled. As yet grids do not appear in +PostScript output. + +Grids have outline like configure options. Grids are created with methods of the +following form: + + $canvas->createGrid(x1, y1, x2, y2, ?option, value, option, value, ...?) + +The arguments I<x1>, I<y1> give the origin of the grid. I<x2>, and I<y2> give +the coordinates of the next grid point in their respective directions. +After the coordinates there may be any number of I<option>-I<value> +pairs, each of which sets one of the configuration options +for the item. These same I<option>-I<value> pairs may be +used in B<itemconfigure> methods to change the item's +configuration. + +The following options are supported for grids: + +=over 4 + +=item B<-lines> =E<gt> I<boolean> + +If B<-lines> is set to a true value then lines are drawn for both X and Y +grids in the style determined by B<-dash>. Otherwise retangular "dots" +are drawn at each grid point. + +=item B<-dash> =E<gt> I<pattern> + +=item B<-disableddash> =E<gt> I<pattern> + +This option specifies dash patterns for the normal state, +and the disabled state of a grid item. +I<pattern> may have any of the forms accepted by B<Tk_GetDash>. +If the dash options are omitted then the default is a solid outline. + +=item B<-dashoffset> =E<gt> I<offset> + +The starting I<offset> into the pattern provided by the +B<-dash> option. +B<-dashoffset> is ignored if there is no B<-dash> pattern. + +=item B<-color> =E<gt> I<color> + +=item B<-disabledcolor> =E<gt> I<color> + +This option specifies the color that should be used to draw the +outline of the grid in its normal and disabled states. +I<Color> may have any of the forms accepted by B<Tk_GetColor>. +This option defaults to B<black>. +If I<color> is undef then no grid will be drawn. + +=item B<-stipple> =E<gt> I<bitmap> + +=item B<-disabledstipple> =E<gt> I<bitmap> + +This option specifies stipple patterns that should be used to draw the +outline of the rectangle in its normal and disabled states. +I<bitmap> specifies the stipple pattern to use, in any of the +forms accepted by B<Tk_GetBitmap>. +If I<bitmap> is an empty string (the default), then the outline is drawn +in a solid fashion. + +=item B<-state> =E<gt> I<state> + +Modifies the state of the rectangle item where I<state> may be set to one of: +normal, disabled, or hidden. Many options can take +separate specifications in normal and disabled states such that the +appearance of the item can be different in each state. + +=item B<-tags> =E<gt> I<tagList> + +Specifies a set of tags to apply to the item. +I<TagList> consists of a list of tag names, which replace any +existing tags for the item. +I<TagList> may be an empty list. + +=item B<-updatecommand> =E<gt> I<command> + +Specifies a callback that is to be executed every time +the grid item is updated on the screen. + +=item B<-width> =E<gt> I<outlineWidth> + +=item B<-disabledwidth> =E<gt> I<outlineWidth> + +Specifies the width of the lines drawn by the grid or the size (in both X and Y) +of the dots, in its normal and disabled states. +This option defaults to 1.0. + +=back + +=head1 IMAGE ITEMS + +Items of type B<image> are used to display images on a +canvas. +Images are created with methods of the following form: + + $canvas->createImage(x, y, ?option, value, option, value, ...?) + +The arguments I<x> and I<y> specify the coordinates of a +point used to position the image on the display (see the B<-anchor> +option below for more information). +After the coordinates there may be any number of I<option>-I<value> +pairs, each of which sets one of the configuration options +for the item. These same I<option>-I<value> pairs may be +used in B<itemconfigure> methods to change the item's +configuration. +The following options are supported for images: + +=over 4 + +=item B<-anchor> =E<gt> I<anchorPos> + +I<AnchorPos> tells how to position the image relative to the +positioning point for the item; it may have any of the forms +accepted by B<Tk_GetAnchor>. For example, if I<anchorPos> +is B<center> then the image is centered on the point; if +I<anchorPos> is B<n> then the image will be drawn so that +its top center point is at the positioning point. +This option defaults to B<center>. + +=item B<-image> =E<gt> I<name> + +=item B<-activeimage> =E<gt> I<name> + +=item B<-disabledimage> =E<gt> I<name> + +Specifies the name of the images to display in the item in is normal, +active and disabled states. This image must have been created +previously, see L<Tk::Image>. + +=item B<-state> =E<gt> I<state> + +Modifies the state of the image item where I<state> may be set to one of: +normal, disabled, or hidden. An image item may also be in the "active" +state if the mouse is currently over it. Many options can take +separate specifications in normal, active and disabled states such that the +appearance of the item can be different in each state. + +=item B<-tags> =E<gt> I<tagList> + +Specifies a set of tags to apply to the item. +I<TagList> consists of a list of tag names, which replace any +existing tags for the item; it may be an empty list. + +=item B<-updatecommand> =E<gt> I<command> + +Specifies a callback that is to be executed every time +the image item is updated on the screen. + +=back + +=head1 LINE ITEMS + +Items of type B<line> appear on the display as one or more connected +line segments or curves. +Line items support coordinate indexing operations using the canvas +methods: B<dchars, index, insert.> +Lines are created with methods of the following form: + + $canvas->createLine(x1, y1..., xn, yn, ?option, value, option, value, ...?) + +The arguments I<x1> through I<yn> give +the coordinates for a series of two or more points that describe +a series of connected line segments. +After the coordinates there may be any number of I<option>-I<value> +pairs, each of which sets one of the configuration options +for the item. These same I<option>-I<value> pairs may be +used in B<itemconfigure> methods to change the item's +configuration. +The following options are supported for lines: + +=over 4 + +=item B<-arrow> =E<gt> I<where> + +Indicates whether or not arrowheads are to be drawn at one or both +ends of the line. +I<Where> must have one of the values B<none> (for no arrowheads), +B<first> (for an arrowhead at the first point of the line), +B<last> (for an arrowhead at the last point of the line), or +B<both> (for arrowheads at both ends). +This option defaults to B<none>. + +=item B<-arrowshape> =E<gt> I<shape> + +This option indicates how to draw arrowheads. +The I<shape> argument must be a list with three elements, each +specifying a distance in any of the forms described in +the L<"COORDINATES"> section above. +The first element of the list gives the distance along the line +from the neck of the arrowhead to its tip. +The second element gives the distance along the line from the +trailing points of the arrowhead to the tip, and the third +element gives the distance from the outside edge of the line to the +trailing points. +If this option isn't specified then Tk picks a ``reasonable'' shape. + +=item B<-capstyle> =E<gt> I<style> + +Specifies the ways in which caps are to be drawn at the endpoints +of the line. +I<Style> may have any of the forms accepted by B<Tk_GetCapStyle> +(B<butt>, B<projecting>, or B<round>). +If this option isn't specified then it defaults to B<butt>. +Where arrowheads are drawn the cap style is ignored. + +=item B<-dash> =E<gt> I<pattern> + +=item B<-activedash> =E<gt> I<pattern> + +=item B<-disableddash> =E<gt> I<pattern> + +This option specifies dash patterns for the normal state, the active +state, and the disabled state of a line item. +I<pattern> may have any of the forms accepted by B<Tk_GetDash>. +If the dash options are omitted then the default is a solid outline. + +=item B<-dashoffset> =E<gt> I<offset> + +The starting I<offset> into the pattern provided by the +B<-dash> option. +B<-dashoffset> is ignored if there is no B<-dash> pattern. + +=item B<-fill> =E<gt> I<color> + +=item B<-activefill> =E<gt> I<color> + +=item B<-disabledfill> =E<gt> I<color> + +Specifies the color to be used to fill the line in its normal, active, and +disabled states. +I<Color> may have +any of the forms acceptable to B<Tk_GetColor>. It may also be undef, +in which case the line will be transparent. +This option defaults to B<black>. + +=item B<-joinstyle> =E<gt> I<style> + +Specifies the ways in which joints are to be drawn at the vertices +of the line. +I<Style> may have any of the forms accepted by B<Tk_GetCapStyle> +(B<bevel>, B<miter>, or B<round>). +If this option isn't specified then it defaults to B<miter>. +If the line only contains two points then this option is +irrelevant. + +=item B<-smooth> =E<gt> I<boolean> + +I<Boolean> must have one of the forms accepted by B<Tk_GetBoolean>. +It indicates whether or not the line should be drawn as a curve. +If so, the line is rendered as a set of parabolic splines: one spline +is drawn for the first and second line segments, one for the second +and third, and so on. Straight-line segments can be generated within +a curve by duplicating the end-points of the desired line segment. + +=item B<-splinesteps> =E<gt> I<number> + +Specifies the degree of smoothness desired for curves: each spline +will be approximated with I<number> line segments. This +option is ignored unless the B<-smooth> option is true. + +=item B<-state> =E<gt> I<state> + +Modifies the state of the line item where I<state> may be set to one of: +normal, disabled, or hidden. A line item may also be in the "active" +state if the mouse is currently over it. Many options can take +separate specifications in normal, active and disabled states such that the +appearance of the item can be different in each state. + +=item B<-stipple> =E<gt> I<bitmap> + +=item B<-activestipple> =E<gt> I<bitmap> + +=item B<-disabledstipple> =E<gt> I<bitmap> + +This option specifies stipple patterns that should be used to fill the +the line in its normal, active and disabled states. +I<bitmap> specifies the stipple pattern to use, in any of the +forms accepted by B<Tk_GetBitmap>. +If I<bitmap> is an empty string (the default), then filling is +done in a solid fashion. + +=item B<-tags> =E<gt> I<tagList> + +Specifies a set of tags to apply to the item. +I<TagList> consists of a list of tag names, which replace any +existing tags for the item. +I<TagList> may be an empty list. + +=item B<-updatecommand> =E<gt> I<command> + +Specifies a callback that is to be executed every time +the line item is updated on the screen. + +=item B<-width> =E<gt> I<lineWidth> + +=item B<-activewidth> =E<gt> I<lineWidth> + +=item B<-disabledwidth> =E<gt> I<lineWidth> + +Specifies the width of the line +in its normal, active and disabled states. +I<lineWidth> may be in any of the forms +described in the L<"COORDINATES"> section above. + +Wide lines will be drawn centered on the path specified by the +points. +If this option isn't specified then it defaults to 1.0. + +=back + +=head1 OVAL ITEMS + +Items of type B<oval> appear as circular or oval regions on +the display. Each oval may have an outline, a fill, or +both. Ovals are created with methods of the +following form: + + $canvas->createOval(x1, y1, x2, y2, ?option, value, option, value, ...?) + +The arguments I<x1>, I<y1>, I<x2>, and I<y2> give +the coordinates of two diagonally opposite corners of a +rectangular region enclosing the oval. +The oval will include the top and left edges of the rectangle +not the lower or right edges. +If the region is square then the resulting oval is circular; +otherwise it is elongated in shape. +After the coordinates there may be any number of I<option>-I<value> +pairs, each of which sets one of the configuration options +for the item. These same I<option>-I<value> pairs may be +used in B<itemconfigure> methods to change the item's +configuration. +The following options are supported for ovals: + +=over 4 + +=item B<-dash> =E<gt> I<pattern> + +=item B<-activedash> =E<gt> I<pattern> + +=item B<-disableddash> =E<gt> I<pattern> + +This option specifies dash patterns for the normal state, the active +state, and the disabled state of an oval item. +I<pattern> may have any of the forms accepted by B<Tk_GetDash>. +If the dash options are omitted then the default is a solid outline. + +=item B<-dashoffset> =E<gt> I<offset> + +The starting I<offset> into the pattern provided by the +B<-dash> option. +B<-dashoffset> is ignored if there is no B<-dash> pattern. + +=item B<-fill> =E<gt> I<color> + +=item B<-activefill> =E<gt> I<color> + +=item B<-disabledfill> =E<gt> I<color> + +Specifies the color to be used to fill the oval in its normal, active, and +disabled states. +I<Color> may have any of the forms accepted by B<Tk_GetColor>. +If I<color> is undef (the default), then +then the oval will not be filled. + +=item B<-outline> =E<gt> I<color> + +=item B<-activeoutline> =E<gt> I<color> + +=item B<-disabledoutline> =E<gt> I<color> + +This option specifies the color that should be used to draw the +outline of the oval in its normal, active and disabled states. +I<Color> may have any of the forms accepted by B<Tk_GetColor>. +This option defaults to B<black>. +If I<color> is undef then no outline will be +drawn for the oval. + +=item B<-outlinestipple> =E<gt> I<bitmap> + +=item B<-activeoutlinestipple> =E<gt> I<bitmap> + +=item B<-disabledoutlinestipple> =E<gt> I<bitmap> + +This option specifies stipple patterns that should be used to draw the +outline of the oval in its normal, active and disabled states. +I<bitmap> specifies the stipple pattern to use, in any of the +forms accepted by B<Tk_GetBitmap>. +If the B<-outline> option hasn't been specified then this option +has no effect. +If I<bitmap> is an empty string (the default), then the outline is drawn +in a solid fashion. + +=item B<-state> =E<gt> I<state> + +Modifies the state of the oval item where I<state> may be set to one of: +normal, disabled, or hidden. An oval item may also be in the "active" +state if the mouse is currently over it. Many options can take +separate specifications in normal, active and disabled states such that the +appearance of the item can be different in each state. + +=item B<-stipple> =E<gt> I<bitmap> + +=item B<-activestipple> =E<gt> I<bitmap> + +=item B<-disabledstipple> =E<gt> I<bitmap> + +This option specifies stipple patterns that should be used to fill the +the oval in its normal, active and disabled states. +I<bitmap> specifies the stipple pattern to use, in any of the +forms accepted by B<Tk_GetBitmap>. +If the B<-fill> option hasn't been specified then this option +has no effect. +If I<bitmap> is an empty string (the default), then filling is done +in a solid fashion. + +=item B<-tags> =E<gt> I<tagList> + +Specifies a set of tags to apply to the item. +I<TagList> consists of a list of tag names, which replace any +existing tags for the item. +I<TagList> may be an empty list. + +=item B<-updatecommand> =E<gt> I<command> + +Specifies a callback that is to be executed every time +the oval item is updated on the screen. + +=item B<-width> =E<gt> I<outlineWidth> + +=item B<-activewidth> =E<gt> I<outlineWidth> + +=item B<-disabledwidth> =E<gt> I<outlineWidth> + +Specifies the width of the outline to be drawn around +the oval, in its normal, active and disabled states. +I<outlineWidth> specifies the width of the outline to be drawn around +the oval, in any of the forms described in the L<"COORDINATES"> section above. + +If the B<-outline> option hasn't been specified then this option +has no effect. +Wide outlines are drawn centered on the oval path defined by +I<x1>, I<y1>, I<x2>, and I<y2>. +This option defaults to 1.0. + +=back + +=head1 POLYGON ITEMS + +Items of type B<polygon> appear as polygonal or curved filled regions +on the display. +Polygon items support coordinate indexing operations using the canvas +methods: B<dchars, index, insert.> +Polygons are created with methods of the following form: + + $canvas->createPolygon(x1, y1, ..., xn, yn, ?option, value, option, value, ...?) + +The arguments I<x1> through I<yn> specify the coordinates for +three or more points that define a closed polygon. +The first and last points may be the same; whether they are or not, +Tk will draw the polygon as a closed polygon. +After the coordinates there may be any number of I<option>-I<value> +pairs, each of which sets one of the configuration options +for the item. These same I<option>-I<value> pairs may be +used in B<itemconfigure> methods to change the item's +configuration. +The following options are supported for polygons: + +=over 4 + +=item B<-dash> =E<gt> I<pattern> + +=item B<-activedash> =E<gt> I<pattern> + +=item B<-disableddash> =E<gt> I<pattern> + +This option specifies dash patterns for the normal state, the active +state, and the disabled state of an polygon item. +I<pattern> may have any of the forms accepted by B<Tk_GetDash>. +If the dash options are omitted then the default is a solid outline. + +=item B<-dashoffset> =E<gt> I<offset> + +The starting I<offset> into the pattern provided by the +B<-dash> option. +B<-dashoffset> is ignored if there is no B<-dash> pattern. + +=item B<-fill> =E<gt> I<color> + +=item B<-activefill> =E<gt> I<color> + +=item B<-disabledfill> =E<gt> I<color> + +Specifies the color to be used to fill the polygon in its normal, active, and +disabled states. +I<Color> +may have any of the forms acceptable to B<Tk_GetColor>. +If I<color> is undef then the polygon will be +transparent. +This option defaults to B<black>. + +=item B<-joinstyle> =E<gt> I<style> + +Specifies the ways in which joints are to be drawn at the vertices +of the outline. +I<Style> may have any of the forms accepted by B<Tk_GetCapStyle> +(B<bevel>, B<miter>, or B<round>). +If this option isn't specified then it defaults to B<miter>. + +=item B<-outline> =E<gt> I<color> + +=item B<-activeoutline> =E<gt> I<color> + +=item B<-disabledoutline> =E<gt> I<color> + +This option specifies the color that should be used to draw the +outline of the polygon in its normal, active and disabled states. +I<Color> may have any of the forms accepted by B<Tk_GetColor>. +If I<color> is undef then no outline will be +drawn for the polygon. +This option defaults to undef (no outline). + +=item B<-outlinestipple> =E<gt> I<bitmap> + +=item B<-activeoutlinestipple> =E<gt> I<bitmap> + +=item B<-disabledoutlinestipple> =E<gt> I<bitmap> + +This option specifies stipple patterns that should be used to draw the +outline of the polygon in its normal, active and disabled states. +I<bitmap> specifies the stipple pattern to use, in any of the +forms accepted by B<Tk_GetBitmap>. +If the B<-outline> option hasn't been specified then this option +has no effect. +If I<bitmap> is an empty string (the default), then the outline is drawn +in a solid fashion. + +=item B<-smooth> =E<gt> I<boolean> + +I<Boolean> must have one of the forms accepted by B<Tk_GetBoolean> +It indicates whether or not the polygon should be drawn with a +curved perimeter. +If so, the outline of the polygon becomes a set of parabolic splines, +one spline for the first and second line segments, one for the second +and third, and so on. Straight-line segments can be generated in a +smoothed polygon by duplicating the end-points of the desired line segment. + +=item B<-splinesteps> =E<gt> I<number> + +Specifies the degree of smoothness desired for curves: each spline +will be approximated with I<number> line segments. This +option is ignored unless the B<-smooth> option is true. + +=item B<-state> =E<gt> I<state> + +Modifies the state of the polygon item where I<state> may be set to one of: +normal, disabled, or hidden. A polygon item may also be in the "active" +state if the mouse is currently over it. Many options can take +separate specifications in normal, active and disabled states such that the +appearance of the item can be different in each state. + +=item B<-stipple> =E<gt> I<bitmap> + +=item B<-activestipple> =E<gt> I<bitmap> + +=item B<-disabledstipple> =E<gt> I<bitmap> + +This option specifies stipple patterns that should be used to fill the +the polygon in its normal, active and disabled states. +I<bitmap> specifies the stipple pattern to use, in any of the +forms accepted by B<Tk_GetBitmap>. +If I<bitmap> is an empty string (the default), then filling is +done in a solid fashion. + +=item B<-tags> =E<gt> I<tagList> + +Specifies a set of tags to apply to the item. +I<TagList> consists of a list of tag names, which replace any +existing tags for the item. +I<TagList> may be an empty list. + +=item B<-updatecommand> =E<gt> I<command> + +Specifies a callback that is to be executed every time +the polygon item is updated on the screen. + +=item B<-width> =E<gt> I<outlineWidth> + +=item B<-activewidth> =E<gt> I<outlineWidth> + +=item B<-disabledwidth> =E<gt> I<outlineWidth> + +=item Specifies the width of the outline to be drawn around + +the polygon, in its normal, active and disabled states. +I<outlineWidth> may be in any of the forms described in the COORDINATES +section above. +I<OutlineWidth> specifies the width of the outline to be drawn around +the polygon, in any of the forms described in the L<"COORDINATES"> section above. +If the B<-outline> option hasn't been specified then this option +has no effect. This option defaults to 1.0. + +Polygon items are different from other items such as rectangles, ovals +and arcs in that interior points are considered to be ``inside'' a +polygon (e.g. for purposes of the B<find closest> and +B<find overlapping> methods) even if it is not filled. +For most other item types, an +interior point is considered to be inside the item only if the item +is filled or if it has neither a fill nor an outline. If you would +like an unfilled polygon whose interior points are not considered +to be inside the polygon, use a line item instead. + +=back + +=head1 RECTANGLE ITEMS + +Items of type B<rectangle> appear as rectangular regions on +the display. Each rectangle may have an outline, a fill, or +both. Rectangles are created with methods of the +following form: + + $canvas->createRectangle(x1, y1, x2, y2, ?option, value, option, value, ...?) + +The arguments I<x1>, I<y1>, I<x2>, and I<y2> give +the coordinates of two diagonally opposite corners of the rectangle +(the rectangle will include its upper and left edges but not +its lower or right edges). +After the coordinates there may be any number of I<option>-I<value> +pairs, each of which sets one of the configuration options +for the item. These same I<option>-I<value> pairs may be +used in B<itemconfigure> methods to change the item's +configuration. +The following options are supported for rectangles: + +=over 4 + +=item B<-dash> =E<gt> I<pattern> + +=item B<-activedash> =E<gt> I<pattern> + +=item B<-disableddash> =E<gt> I<pattern> + +This option specifies dash patterns for the normal state, the active +state, and the disabled state of a rectangle item. +I<pattern> may have any of the forms accepted by B<Tk_GetDash>. +If the dash options are omitted then the default is a solid outline. + +=item B<-dashoffset> =E<gt> I<offset> + +The starting I<offset> into the pattern provided by the +B<-dash> option. +B<-dashoffset> is ignored if there is no B<-dash> pattern. + +=item B<-fill> =E<gt> I<color> + +=item B<-activefill> =E<gt> I<color> + +=item B<-disabledfill> =E<gt> I<color> + +Specifies the color to be used to fill the rectangle in its normal, active, and +disabled states. +I<Color> +may be specified in any of the forms accepted by B<Tk_GetColor>. +If I<color> is undef (the default), +then the rectangle will not be filled. + +=item B<-outline> =E<gt> I<color> + +=item B<-activeoutline> =E<gt> I<color> + +=item B<-disabledoutline> =E<gt> I<color> + +This option specifies the color that should be used to draw the +outline of the rectangle in its normal, active and disabled states. +I<Color> may have any of the forms accepted by B<Tk_GetColor>. +This option defaults to B<black>. +If I<color> is undef then no outline will be +drawn for the rectangle. + +=item B<-outlinestipple> =E<gt> I<bitmap> + +=item B<-activeoutlinestipple> =E<gt> I<bitmap> + +=item B<-disabledoutlinestipple> =E<gt> I<bitmap> + +This option specifies stipple patterns that should be used to draw the +outline of the rectangle in its normal, active and disabled states. +I<bitmap> specifies the stipple pattern to use, in any of the +forms accepted by B<Tk_GetBitmap>. +If the B<-outline> option hasn't been specified then this option +has no effect. +If I<bitmap> is an empty string (the default), then the outline is drawn +in a solid fashion. + +=item B<-state> =E<gt> I<state> + +Modifies the state of the rectangle item where I<state> may be set to one of: +normal, disabled, or hidden. A rectangle item may also be in the "active" +state if the mouse is currently over it. Many options can take +separate specifications in normal, active and disabled states such that the +appearance of the item can be different in each state. + +=item B<-stipple> =E<gt> I<bitmap> + +=item B<-activestipple> =E<gt> I<bitmap> + +=item B<-disabledstipple> =E<gt> I<bitmap> + +This option specifies stipple patterns that should be used to fill the +the rectangle in its normal, active and disabled states. +I<bitmap> specifies the stipple pattern to use, in any of the +forms accepted by B<Tk_GetBitmap>. +If the B<-fill> option hasn't been specified then this option +has no effect. +If I<bitmap> is an empty string (the default), then filling +is done in a solid fashion. + +=item B<-tags> =E<gt> I<tagList> + +Specifies a set of tags to apply to the item. +I<TagList> consists of a list of tag names, which replace any +existing tags for the item. +I<TagList> may be an empty list. + +=item B<-updatecommand> =E<gt> I<command> + +Specifies a callback that is to be executed every time +the rectangle item is updated on the screen. + +=item B<-width> =E<gt> I<outlineWidth> + +=item B<-activewidth> =E<gt> I<outlineWidth> + +=item B<-disabledwidth> =E<gt> I<outlineWidth> + +Specifies the width of the outline to be drawn around +the rectangle, in its normal, active and disabled states. +I<OutlineWidth> specifies the width of the outline to be drawn around +the rectangle, in any of the forms described in the L<"COORDINATES"> section above. + +If the B<-outline> option hasn't been specified then this option +has no effect. +Wide outlines are drawn centered on the rectangular path +defined by I<x1>, I<y1>, I<x2>, and I<y2>. +This option defaults to 1.0. + +=back + +=head1 TEXT ITEMS + +A text item displays a string of characters on the screen in one +or more lines. +Text items support indexing and selection, along with the +following text-related canvas methods: B<dchars>, +B<focus>, B<icursor>, B<index>, B<insert>, +B<select>. +Text items are created with methods of the following +form: + + $canvas->createText(x, y, ?option, value, option, value, ...?) + +The arguments I<x> and I<y> specify the coordinates of a +point used to position the text on the display (see the options +below for more information on how text is displayed). +After the coordinates there may be any number of I<option>-I<value> +pairs, each of which sets one of the configuration options +for the item. These same I<option>-I<value> pairs may be +used in B<itemconfigure> methods to change the item's +configuration. +The following options are supported for text items: + +=over 4 + +=item B<-anchor> =E<gt> I<anchorPos> + +I<AnchorPos> tells how to position the text relative to the +positioning point for the text; it may have any of the forms +accepted by B<Tk_GetAnchor>. For example, if I<anchorPos> +is B<center> then the text is centered on the point; if +I<anchorPos> is B<n> then the text will be drawn such that +the top center point of the rectangular region occupied by the +text will be at the positioning point. +This option defaults to B<center>. + +=item B<-fill> =E<gt> I<color> + +=item B<-activefill> =E<gt> I<color> + +=item B<-disabledfill> =E<gt> I<color> + +Specifies the color to be used to fill the text in its normal, active, and +disabled states. +I<Color> may have any of the forms accepted by B<Tk_GetColor>. +If I<color> is undef then the text will be transparent. +If this option isn't specified then it defaults to B<black>. + +=item B<-font> =E<gt> I<fontName> + +Specifies the font to use for the text item. +I<FontName> may be any string acceptable to B<Tk_GetFontStruct>. +If this option isn't specified, it defaults to a system-dependent +font. + +=item B<-justify> =E<gt> I<how> + +Specifies how to justify the text within its bounding region. +I<How> must be one of the values B<left>, B<right>, +or B<center>. +This option will only matter if the text is displayed as multiple +lines. +If the option is omitted, it defaults to B<left>. + +=item B<-state> =E<gt> I<state> + +Modifies the state of the text item where I<state> may be set to one of: +normal, disabled, or hidden. A text item may also be in the "active" +state if the mouse is currently over it. Many options can take +separate specifications in normal, active and disabled states such that the +appearance of the item can be different in each state. + +=item B<-stipple> =E<gt> I<bitmap> + +=item B<-activestipple> =E<gt> I<bitmap> + +=item B<-disabledstipple> =E<gt> I<bitmap> + +This option specifies stipple patterns that should be used to fill the +the text in its normal, active and disabled states. +I<bitmap> specifies the stipple pattern to use, in any of the +forms accepted by B<Tk_GetBitmap>. +If I<bitmap> is an empty string (the default) then the text +is drawn in a solid fashion. + +=item B<-tags> =E<gt> I<tagList> + +Specifies a set of tags to apply to the item. +I<TagList> consists of a list of tag names, which replace any +existing tags for the item. +I<TagList> may be an empty list. + +=item B<-text> =E<gt> I<string> + +I<String> specifies the characters to be displayed in the text item. +Newline characters cause line breaks. +The characters in the item may also be changed with the +B<insert> and B<delete> methods. +This option defaults to an empty string. + +=item B<-updatecommand> =E<gt> I<command> + +Specifies a callback that is to be executed every time +the text item is updated on the screen. + +=item B<-width> =E<gt> I<lineLength> + +Specifies a maximum line length for the text, in any of the forms +described in the L<"COORDINATES"> section above. +If this option is zero (the default) the text is broken into +lines only at newline characters. +However, if this option is non-zero then any line that would +be longer than I<lineLength> is broken just before a space +character to make the line shorter than I<lineLength>; the +space character is treated as if it were a newline +character. + +=back + +=head1 WINDOW ITEMS + +Items of type B<window> cause a particular window to be displayed +at a given position on the canvas. +Window items are created with methods of the following form: + +S< >I<$canvas>->B<createWindow>(I<x, y>?, I<-option>=>I<value>, I<-option>=>I<value>, ...?) + +The arguments I<x> and I<y> specify the coordinates of a +point used to position the window on the display (see the B<-anchor> +option below for more information on how bitmaps are displayed). +After the coordinates there may be any number of I<option-value> +pairs, each of which sets one of the configuration options +for the item. These same I<option>-I<value> pairs may be +used in B<itemconfigure> method to change the item's +configuration. +The following options are supported for window items: + +=over 4 + +=item B<-anchor> =E<gt> I<anchorPos> + +I<AnchorPos> tells how to position the window relative to the +positioning point for the item; it may have any of the forms +accepted by B<Tk_GetAnchor>. For example, if I<anchorPos> +is B<center> then the window is centered on the point; if +I<anchorPos> is B<n> then the window will be drawn so that +its top center point is at the positioning point. +This option defaults to B<center>. + +=item B<-height> =E<gt> I<pixels> + +Specifies the height to assign to the item's window. +I<Pixels> may have any of the +forms described in the L<"COORDINATES"> section above. +If this option isn't specified, or if it is specified as an empty +string, then the window is given whatever height it requests internally. + +=item B<-state> =E<gt> I<state> + +Modifies the state of the window item where I<state> may be set to one of: +normal, disabled, or hidden. + +=item B<-tags> =E<gt> I<tagList> + +Specifies a set of tags to apply to the item. +I<TagList> consists of a list of tag names, which replace any +existing tags for the item. +I<TagList> may be an empty list. + +=item B<-updatecommand> =E<gt> I<command> + +Specifies a callback that is to be executed every time +the window item is updated on the screen. + +=item B<-width> =E<gt> I<pixels> + +Specifies the width to assign to the item's window. +I<Pixels> may have any of the +forms described in the L<"COORDINATES"> section above. +If this option isn't specified, or if it is specified as an empty +string, then the window is given whatever width it requests internally. + +=item B<-window> =E<gt> I<$widget> + +Specifies the window to associate with this item. +The window specified by $widget must either be a child of +the canvas widget or a child of some ancestor of the canvas widget. +I<PathName> may not refer to a top-level window. + +Note: due to restrictions in the ways that windows are managed, it is not +possible to draw other graphical items (such as lines and images) on top +of window items. A window item always obscures any graphics that +overlap it, regardless of their order in the display list. + +=back + +=head1 APPLICATION-DEFINED ITEM TYPES + +It is possible for individual applications to define new item +types for canvas widgets using C code. +See the documentation for B<Tk_CreateItemType>. + +=head1 BINDINGS + +Canvas has default bindings to allow scrolling if necessary: +<Up>, <Down>, <Left> and <Right> (and their <Control-*> counter +parts). Further <Proir>, <Next>, <Home> and <End>. These +bindings allow you to navigate the same way as in other +widgets that can scroll. + +=head1 Perl/Tk Methods + +The following methods are added as perl code: + +=over 4 + +=item $canvas->get_corners + +Returns the bounding box in Canvas coordinates of the visible portion +of the Canvas. (Written by Slaven Rezic.) + +=back + +=head1 CREDITS + +Tk's canvas widget is a blatant ripoff of ideas from Joel Bartlett's +I<ezd> program. I<Ezd> provides structured graphics in a Scheme +environment and preceded canvases by a year or two. Its simple +mechanisms for placing and animating graphical objects inspired the +functions of canvases. + +=head1 KEYWORDS + +canvas, widget + +=cut + |