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diff --git a/Master/tlpkg/tlperl/lib/Tk/DItem.pod b/Master/tlpkg/tlperl/lib/Tk/DItem.pod new file mode 100644 index 00000000000..27db79744df --- /dev/null +++ b/Master/tlpkg/tlperl/lib/Tk/DItem.pod @@ -0,0 +1,439 @@ +=head1 NAME + +Tk::DItem - Tix Display Items + +=for category Tix Extensions + +=head1 SYNOPSIS + +=head1 DESCRIPTION + +The Tix B<Display Items> and B<Display Types> are devised to +solve a general problem: many Tix widgets (both existing and planned +ones) display many items of many types simultaneously. + +For example, a hierarchical listbox widget (see L<Tk::HList>) can display +items +of images, plain text and subwindows in the form of a +hierarchy. Another widget, the tabular listbox widget (see L<Tk::TList>) +also displays items of the +same types, although it arranges the items in a tabular form. Yet +another widget, the spreadsheet widget (see L<Tk::TixGrid>), +also displays similar types +items, but in yet another format. + +In these examples, the display items in different widgets are only +different in how they are arranged by the B<host widget>. In Tix, +display items are clearly separated from the host widgets. The +advantage is two-fold: first, the creation and configuration of +display items become uniform across different host widgets. Second, +new display item types can be added without the need to modify the +existing host widgets. + +In a way, Tix display items are similar to the items inside Tk +the canvas widget. However, unlike the Tix display items, the canvas +items are not independent of the canvas widget; this makes it +impossible to use the canvas items inside other types of TK widgets. + +The appearance of a display item is controlled by a set of +I<attributes>. It is observed that each the attributes usually fall +into one of two categroies: ``I<individual>'' or +``I<collective>''. For example, the text items inside a HList widget +may all display a different text string; however, in most cases, the +text items share the same color, font and spacing. Instead of keeping +a duplicated version of the same attributes inside each display item, +it will be advantageous to put the collective attributes in a +special object called a B<display style>. First, there is the space +concern: a host widget may have many thousands of items; keeping +dupilcated attributes will be very wasteful. Second, when it becomes +necessary to change a collective attribute, such as changing all the +text items' foreground color to red, it will be more efficient to +change only the display style object than to modify all the text +items one by one. + +The attributes of the a display item are thus stored in two places: it +has a set of B<item options> to store its individual attributes. Each +display item is also associated with a I<display style>, which specifies +the collective attributes of all items associated with itself. + +The division between the individual and collective attributes are +fixed and cannot be changed. Thus, when it becomes necessary for some +items to differ in their collective attributes, two or more B<display styles> +can be used. For example, suppose you want to display two +columns of text items inside an HList widget, one column in red and +the other in blue. You can create a TextStyle object called ``$red'' +which defines a red foreground, and another called ``$blue'', which +defines a blue foreground. You can then associate all text items of +the first column to ``$red'' and the second column to ``$blue'' + +=head1 DISPLAY ITEM TYPES AND OPTIONS + +Currently there are three types of display items: B<text>, +B<imagetext> and I<window>. + +=head1 IMAGETEXT ITEMS + +Display items of the type B<imagetext> are used to display an image +together with a text string. Imagetext items support the following options: + +=head2 Imagetext Item Options + +=over 4 + +=item Name: B<bitmap> + +=item Class: B<Bitmap> + +=item Switch: B<-bitmap> + +Specifies the bitmap to display in the item. + +=item Name: B<image> + +=item Class: B<Image> + +=item Switch: B<-image> + +Specifies the image to display in the item. When both the +B<-bitmap> and B<-image> options are specified, only the image +will be displayed. + +=item Name: B<imageTextStyle> + +=item Class: B<ImageTextStyle> + +=item Switch: B<-style> + +Specifies the display style to use for this item. Must be the +name of a B<imagetext> display style that has already be created with +B<ItemStyle>. + +=item Name: B<showImage> + +=item Class: B<ShowImage> + +=item Switch: B<-showimage> + +A Boolean value that specifies whether the image/bitmap should be +displayed. + +=item Name: B<showText> + +=item Class: B<ShowText> + +=item Switch: B<-showtext> + +A Boolean value that specifies whether the text string should be +displayed. + +=item Name: B<text> + +=item Class: B<Text> + +=item Switch: B<-text> + +Specifies the text string to display in the item. + +=item Name: B<underline> + +=item Class: B<Underline> + +=item Switch: B<-underline> + +Specifies the integer index of a character to underline in the text +string in the item. 0 corresponds to the first character of the text +displayed in the widget, 1 to the next character, and so on. + +=back + +=head2 Imagetext Style Options + +The style information of B<imagetext> items are stored in the +B<imagetext> display style. The following options are supported: + +B<STANDARD OPTIONS> + +B<-activebackground> B<-activeforeground> +B<-anchor> B<-background> +B<-disabledbackground> B<-disabledforeground> +B<-foreground> B<-font> +B<-justify> B<-padx> +B<-pady> B<-selectbackground> +B<-selectforeground> B<-wraplength> + +See L<Tk::options> for details of the standard options. + +B<STYLE-SPECIFIC OPTIONS> + +=over 4 + +=item Name: B<gap> + +=item Class: B<Gap> + +=item Switch: B<-gap> + +Specifies the distance between the bitmap/image and the text string, +in number of pixels. + +=item Name: B<textAnchor> + +=item Class: B<TextAnchor> + +=item Switch: B<-textanchor> + +The anchor position on the image to which text part is attached. +This is a perl/Tk addition. Defaults to B<e> for compatibility with standard +Tix. The interesting cases are + +=over 8 + +=item B<n> + +Text is centred above the image. + +=item B<s> + +Text is centred below the image + +=item B<e> + +Text is centred to right of the image. + +=item B<w> + +Text is centred to left of the image. + +=item B<c> + +Text is centred over the image. + +=back + +The B<sw>, B<se>, B<ne>, and b<nw> cases look rather odd. + +To get items to line up correctly it will usually be necessary +to specify B<-anchor> as well. e.g. with default B<e> then anchoring +item as a whole B<w> lines images up down left with text stuck to right side. + +=back + +=head1 TEXT ITEMS + +Display items of the type B<text> are used to display a text string +in a widget. Text items support the following options: + +=head2 Text Item Options + +=over 4 + +=item Name: B<textStyle> + +=item Class: B<TextStyle> + +=item Switch: B<-style> + +Specifies the display style to use for this text item. Must be the +name of a B<text> display style that has already be created with +B<ItemStyle>. + +=item Name: B<text> + +=item Class: B<Text> + +=item Switch: B<-text> + +Specifies the text string to display in the item. + +=item Name: B<underline> + +=item Class: B<Underline> + +=item Switch: B<-underline> + +Specifies the integer index of a character to underline in the item. +0 corresponds to the first character of the text displayed in the +widget, 1 to the next character, and so on. + +=back + +=head2 Text Style Options + +B<STANDARD OPTIONS> + +B<-activebackground> B<-activeforeground> +B<-anchor> B<-background> +B<-disabledbackground> B<-disabledforeground> +B<-foreground> B<-font> +B<-justify> B<-padx> +B<-pady> B<-selectbackground> +B<-selectforeground> B<-wraplength> + +See L<Tk::options> for details of the standard options. + +=head1 WINDOW ITEMS + +Display items of the type I<window> are used to display a +sub-window in a widget. B<Window> items support the following +options: + +=head2 Window Item Options + +=over 4 + +=item Name: B<windowStyle> + +=item Class: B<WindowStyle> + +=item Switch: B<-style> + +Specifies the display style to use for this window item. Must be the +name of a I<window> display style that has already be created with +the B<ItemStyle> method. + +=item Name: B<window> + +=item Class: B<Window> + +=item Switch: B<-window> + +=item Alias: B<-widget> + +Specifies the sub-window to display in the item. + +=back + +=head2 Window Style Options + +B<STYLE STANDARD OPTIONS> + +B<-anchor> B<-padx> B<-pady> + +See L<Tk::options> for details of the standard options. + +=head1 CREATING DISPLAY ITEMS + +Display items do not exist on their and thus they cannot be created +independently of the widgets they reside in. As a rule, display items +are created by special methods of their ``host'' widgets. For +example, the HList widgets has a method B<item> which can be used +to create new display items. The following code creates a new text +item at the third column of the entry foo inside an HList widget: + + my $hlist = $parent->HList(-columns=>3); + $hlist->add('foo'); + $hlist->itemCreate('foo', 2, -itemtype=>'text', -text=>'Hello'); + +The B<itemCreate> method of the HList widget accepts a variable +number of arguments. The special argument B<-itemtype> specifies +which type of display item to create. Options that are valid for this +type of display items can then be specified by one or more +I<option-value> pairs. + +After the display item is created, they can then be configured or +destroyed using the methods provided by the host widget. For example, +the HList widget has the methods B<itemConfigure>, B<itemCget> +and B<itemDelete> for accessing the display items. + +=head1 CREATING AND MANIPULATING ITEM STYLES + +Item styles are created with B<ItemStyle>: + +=head1 SYNOPSIS + +S< >I<$widget>-E<gt>B<ItemStyle>(I<itemType> ?,B<-stylename>=E<gt>I<name>? ?,B<-refwindow>=E<gt>I<pathName>? ?,I<option>=E<gt>I<value>, ...>?); + +I<itemType> must be one of the existing display items types such as +B<text>, B<imagetext>, B<window> or any new types added by +the user. Additional arguments can be given in one or more +I<option-value> pairs. I<option> can be any of the valid option +for this display style or any of the following: + +=over 4 + +=item B<-stylename> =E<gt> I<name> + +Specifies a name for this style. If unspecified, then a default name +will be chosen for this style. + +=item B<-refwindow> =E<gt> I<$otherwidget> + +Specifies a window to use for determine the default values of the +display type. If unspecified, the I<$widget> will be used. Default +values for the display types can be set via the options database. The +following example sets the B<-disablebackground> and +B<-disabledforeground> options of a B<text> display style via +the option database: + + $widget->optionAdd('*table.list*disabledForeground' => 'blue'); + $widget->optionAdd('*table.list*disabledBackground' => 'darkgray'); + $widget->ItemStyle('text', -refwindow => $table_list, -fg => 'red'); + +By using the option database to set the options of the display styles, +we can advoid hard-coding the option values and give the user more +flexibility in customization. See L<Tk::option> for a detailed description +of the option database. + +=back + +=head1 STYLE METHODS + +The B<ItemStyle> method creates an object. +This object supports the B<configure> and B<cget> methods +described in L<Tk::options> which can be used to enquire and +modify the options described above. + +The following additional methods are available for item styles: + +=over 4 + +=item I<$style>-E<gt>B<delete> + +Destroy this display style object. + +=back + +=head1 EXAMPLE + +The following example creates two columns of data in a HList +widget. The first column is in red and the second column in blue. The +colors of the columns are controlled by two different B<text> +styles. Also, the anchor and font of the second column is chosen so +that the income data is aligned properly. + + use strict; + use Tk; + use Tk::HList; + use Tk::ItemStyle; + + my $mw = MainWindow->new(); + + my $hlist = $mw->HList(-columns=>2)->pack; + + my $red = $hlist->ItemStyle('text', -foreground=>'#800000'); + my $blue = $hlist->ItemStyle('text', -foreground=>'#000080', -anchor=>'e'); + + my $e; + foreach ([Joe => '$10,000'], [Peter => '$20,000'], + [Raj => '$90,000'], [Zinh => '$0']) { + $e = $hlist->addchild(""); + $hlist->itemCreate($e, 0, -itemtype=>'text', + -text=>$_->[0], -style=>$red ); + $hlist->itemCreate($e, 1, -itemtype=>'text', + -text=>$_->[1], -style=>$blue); + } + + Tk::MainLoop; + +=head1 SEE ALSO + +L<Tk::HList|Tk::HList> +L<Tk::TixGrid|Tk::TixGrid> +L<Tk::TList|Tk::TList> + +=head1 KEYWORDS + +display item, display style, item style + +=cut + |