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diff --git a/Master/texmf-dist/doc/latex/beamer/beamerug-color.tex b/Master/texmf-dist/doc/latex/beamer/beamerug-color.tex new file mode 100644 index 00000000000..c83e8109c52 --- /dev/null +++ b/Master/texmf-dist/doc/latex/beamer/beamerug-color.tex @@ -0,0 +1,901 @@ +% $Header: /cvsroot/latex-beamer/latex-beamer/doc/beamerug-color.tex,v 1.24 2005/10/23 16:55:54 tantau Exp $ + +% Copyright 2003, 2004 by Till Tantau <tantau@users.sourceforge.net>. +% +% This program can be redistributed and/or modified under the terms +% of the GNU Public License, version 2. + +\section{Colors} + +\label{section-colors} + +\beamer's color management allows you to specify the color of every +element (like, say, the color of the section entries in a table of +contents or, say, the color of the subsection entries in a mini table +of contents in a sidebar). While the system is quite powerful, it is +not trivial to use. To simplify the usage of the color system, you +should consider using a predefined color theme, which takes care of +everything for you. + +In the following, color themes are explained first. The rest of the +section consists of explanations of how the color management works +internally. You will need to read these sections only if you wish to +write your own color themes; or if you are quite happy with the +predefined themes but you absolutely insist that displayed +mathematical text simply has to be typeset in a lovely pink. + + + +\subsection{Color Themes} + +In order to also show the effect of the different color themes on the +sidebar, in the following examples the color themes are used together +with the outer theme |sidebar|. + +\subsubsection{Default and Special-Purpose Color Themes} + +\begin{colorthemeexample}{default} + The |default| color theme is very sober. It installs little special + colors and even less backgrounds. The default color theme sets up + the default parent relations between the different \beamer-colors. + + The main colors set in the |default| color theme are the following: + \begin{itemize} + \item + |normal text| is black on white. + \item + |alerted text| is red. + \item + |example text| is a dark green (green with 50\% black). + \item + |structure| is set to a light version of MidnightBlue + (more precisely, 20\% red, 20\% green, and 70\% blue). + \end{itemize} + Use this theme for a no-nonsense presentation. Since this theme is + loaded by default, you cannot ``reload'' it after having loaded + another color theme. +\end{colorthemeexample} + +\begin{colorthemeexample}[\oarg{options}]{structure} + The example was created using |\usecolortheme[named=SeaGreen]{structure}|. + + This theme offers a convenient way of changing the color used for + structural elements. More precisely, it just changes the foreground + of the \beamer-color |structure|. You can also achieve this by + directly invoking the function |\setbeamercolor|, but this color + theme makes things a bit easier. + + The theme offers several \meta{options}, which can be used to + specify the color to be used for structural elements: + \begin{itemize} + \item + \declare{|rgb=|\marg{rgb tuple}} sets the |structure| foreground + to the specified red-green-blue tuple. The numbers are given as + decimals between 0 and 1. For example, |rgb={0.5,0,0}| yields a + dark red. + \item + \declare{|RGB=|\marg{rgb tuple}} does the same as |rgb|, except + that the numbers range between 0 and 255. For example, + |RGB={128,0,0}| yields a dark red. + \item + \declare{|cmyk=|\marg{cymk tuple}} sets the |structure| foreground + to the specified cyan-magenta-yellow-black tuple. The numbers are + given as decimals between 0 and 1. For example, |cymk={0,1,1,0.5}| + yields a dark red. + \item + \declare{|cmy=|\marg{cym tuple}} is similar to |cmyk|, except that + the black component is not specified. + \item + \declare{|hsb=|\marg{hsb tuple}} sets the |structure| foreground + to the specified hue-saturation-brightness tuple. The numbers are + given as decimals between 0 and 1. For example, |hsb={0,1,.5}| + yields a dark red. + \item + \declare{|named=|\marg{color name}} sets the |structure| foreground + to a named color. This color must previously have been defined + using the |\DefineNamedColor| command. Adding the class option + |xcolor=dvipsnames| will install a long list of standard + names. See the file |dvipsnam.def| for the list. + \end{itemize} +\end{colorthemeexample} + +\begin{colorthemeexample}{sidebartab} + This theme changes the colors in a sidebar such that the current + entry in a table of contents shown there gets hilighted by showing a + different background behind it. +\end{colorthemeexample} + + + +\subsubsection{Complete Color Themes} + +A ``complete'' color theme is a color theme that completely specifies +all colors for all parts of a frame. It installs specific colors and +does not derive the colors from, say, the |structure| \beamer-color. +Complete color themes happen to have names of flying animals. + +\begin{colorthemeexample}{albatross} + The color theme is a ``dark'' or ``inverted'' theme using yellow on + blue as the main colors. The color theme also installs a slightly + darker background color for blocks, which is necessary for + presentation themes that use shadows, but which (in my opinion) is + undesirable for all other presentation themes. By using the |lily| + color theme together with this theme, the backgrounds for blocks can + be removed. + + When using a light-on-dark theme like this one, be aware that there + are certain disadvantages: + \begin{itemize} + \item + If the room in which the talk is given has been ``darkened,'' + using such a theme makes it more difficult for the audience to + take or read notes. + \item + Since the room becomes darker, the pupil becomes larger, thus + making it harder for the eye to focus. This \emph{can} make text + harder to read. + \item + Printing such slides is difficult at best. + \end{itemize} + + On the other hand, a light-on-dark presentation often appears to be + more ``stylish'' than a plain black-on-white one. + + The following \meta{options} may be given: + \begin{itemize} + \item \declare{|overlystylish|} installs a background canvas that + is, in my opinion, way too stylish. But then, I do not want + to press my taste on other people. When using this option, it is + probably a very good idea to also use the |lily| color theme. + \end{itemize} + + \example The |overlystylish| option together with the |lily| color theme: + \genericthemeexample{colorthemealbatrossstylish} +\end{colorthemeexample} + + +\begin{colorthemeexample}{beetle} + The main ``theme behing this theme'' is to use white and black text + on gray background. The white text is used for special emphasis, the + black text for normal text. The ``outer stuff'' like the headline + and the footline use, however, a bluish color. To change this color, + change the background of |palette primary|. + + Great care must be taken with this theme since both the white/gray + and the black/gray contrasts are much lower than with other + themes. Make sure that the contrast is high enough for the actual + presentation. + + You can change the ``grayish'' background by changing the background + of |normal text|. +\end{colorthemeexample} + +\begin{colorthemeexample}{crane} + This theme uses the colors of the Lufthansa, whose logo is a + crane. It is \emph{not} an official theme by that company, however. +\end{colorthemeexample} + +\begin{colorthemeexample}{dove} + This theme is nearly a black and white theme and useful for creating + presentations that are easy to print on a black-and-white + printer. The theme uses grayscale in certain unavoidable cases, but + never color. It also changes the font of alerted text to boldface. + + When using this theme, you should consider using the class option + |gray|, which ensures that all colors are converted to + grayscale. Also consider using the |structurebold| font theme. +\end{colorthemeexample} + + +\begin{colorthemeexample}{fly} + This theme is the ``consequent'' version of |beetle| and uses + white/black/gray throughout. It does not go particularly well with + themes that use shadows. +\end{colorthemeexample} + +\begin{colorthemeexample}{seagull} + Like the |dove| color theme, this theme is useful for printing on a + black-and-white printer. However, it uses different shades of gray + extensively, which may or may not look good on a transparency. +\end{colorthemeexample} + + +\begin{colorthemeexample}{wolverine} + The theme is based on the colors of the University of Michigan's + mascot, a wolverine. + + \themeauthor Madhusudan Singh. +\end{colorthemeexample} + + +\begin{colorthemeexample}{beaver} + The theme is based on the colors of the MIT's mascot, a beaver. + + \themeauthor Madhusudan Singh. +\end{colorthemeexample} + + +\subsubsection{Inner Color Themes} + +Inner color themes only specify the colors of elements used in inner +themes. Most noticably, they specify the colors used for blocks. They can +be used together with other (color) themes. If they are used to change the +inner colors installed by a presentation theme or another color theme, +they should obviously be specified \emph{after} the other theme has +been loaded. Inner color themes happen to have flower names. + +\begin{colorthemeexample}{lily} + This theme is mainly used to \emph{uninstall} any block colors setup + by another theme, restoring the colors used in the |default| + theme. In particular, using this theme will remove all background + colors for blocks. +\end{colorthemeexample} + +\begin{colorthemeexample}{orchid} + This theme installs white-on-dark block titles. The background of + the title of a normal block is set to the foreground of the + structure color, the foreground is set to white. The background of + alerted blocks are set to red and of example blocks to green. The + body of blocks get a nearly transparent background. +\end{colorthemeexample} + +\begin{colorthemeexample}{rose} + This theme installs nearly transparent backgrounds for both block + titles and block bodies. This theme is much less ``aggressive'' than + the |orchid| theme. The background colors are derived from the + foreground of the structure \beamer-color. +\end{colorthemeexample} + + +\subsubsection{Outer Color Themes} + +An outer color theme changes the palette colors, on which the colors +used in the headline, footline, and sidebar +are based by default. Outer color themes normally do not change the +color of inner elements, except possibly for |titlelike|. They have +happen to sea-animal names. + +\begin{colorthemeexample}{whale} + Installs a white-on-dark palette for the headline, footline, and + sidebar. The backgrounds used there are set to shades between the + structure \beamer-color and black. The foreground is set to + white. + + While this color theme can appear to be aggressive, you should note + that a dark bar at the border of a frame will have a somewhat + different appearance during a presentation than it has on paper: + During a presentation the projection on the + wall is usually surrounded by blackness. Thus, a dark bar will + not create a contrast as opposed to the way it does on + paper. Indeed, using this theme will cause the main part of the + frame to be more at the focus of attention. + + The counterpart to the theme with respect to blocks is the |orchid| + theme. However, pairing it with the |rose| color theme is also + interesting. +\end{colorthemeexample} + +\begin{colorthemeexample}{seahorse} + Installs a near-transparent backgrounds for the headline, footline, + and sidebar. Using this theme will cause navigational elements to be + much less ``dominant'' than when using the |whale| theme (see the + discussion on contrast there, though). + + It goes well with the |rose| or the |lily| color theme. Pairing it + with the |orchid| overemphasizes blocks (in my opinion). +\end{colorthemeexample} + + +\begin{colorthemeexample}{dolphin} + A color theme somewhere in the middle between the whale and the + seahorse. It was graciously donated by Manuel Carro. Like the + seahorse, it goes well with the |rose| and the |lily| color theme. +\end{colorthemeexample} + + + + +\subsection{Changing the Colors Used for Different Elements of a Presentation} + +This section explains how \beamer's color management works. + + + +\subsubsection{Overview of Beamer's Color Management} + +In \beamer's philosophy, every element of a presentation can have a +different color. Unfortunately, it turned out that simply assigning a +single color to every element of a presentation is not such a good +idea. First of all, we sometimes want colors of elements to change +during a presentation, like the color of the item indicators when they +become alerted or inside an example block. Second, some elements +naturally have two colors, namely a foreground and a background, but +not always. Third, sometimes element somehow should not have any +special color but should simply ``run along'' with the color of their +surrounding. Finally, giving a special color to every element makes it +very hard to globally change colors (like changing all the different +kind-of-blue things into kind-of-red things) and it makes later +extensions even harder. + +For all these reasons, the color of an element in \beamer\ is a +structured object, which I call a \emph{\beamer-color}. Every +\beamer-color has two parts: a foreground and a background. Either of +these may be ``empty,'' which means that whatever foreground or +background was active before should remain active when the color is +used. + +\beamer-colors can \emph{inherit} from other \beamer-colors and the +default themes make extensive use of this feature. For example, there +is a \beamer-color called |structure| and all sorts of elements +inherit from this color. Thus, if someone changes |structure|, the +color of all these elements automatically change accordingly. When a +color inherits from another color, it can nevertheless still override +only the foreground or the background. + +It is also possible to ``inherit'' from another \beamer-color in a more +sophisticated way, which is more like \emph{using} the other +\beamer-color in an indirect way. You can specify that, say, the +background of the title should be a 90\% of the background of normal +text and 10\% of the foreground of |structure|. + +Inheritance and using of other \beamer-colors is done +dynamically. This means that if one of the parent \beamer-colors +changes during the presentation, the derived colors automatically also +change. + +The default color theme, which is always loaded, installs numerous +\beamer-colors and inheritance relations between them. These colors +are explained throughout this guide. The color used for, say, +frametitles is discussed in the section on frametitles, and so on. + + +\subsubsection{Using Beamer's Colors} + +A \beamer-color is not a normal color as defined by the |color| and +|xcolor| packages and, accordingly, cannot be used directly as in +commands like |\color| or |\colorlet|. Instead, in order to use a +\beamer-color, you should first call the command |\usebeamercolor|, +which is explained below. This command will setup two (normal) colors +called |fg| (for foreground) and |bg| (for, well, guess what). You can +then say |\color{fg}| to install the foreground color and +|\color{bg}| to install the background color. You can also use the +colors |fg| and |bg| in any context in which you normally use a color +like, say, |red|. If a \beamer-color does not have a foreground or a +background, the colors |fg| or |bg| (or both) remain unchanged. + +Inside templates, this command will typically have already been called +for you with the option |[fg]|. + +\begin{command}{\usebeamercolor\opt{|*|}\oarg{fg or + bg}\marg{beamer-color name}} + This command (possibly) changes the two colors |fg| and |bg| to the + foreground and background color of the \meta{beamer-color name}. If + the \beamer-color does not specify a foreground, |fg| is left + unchanged; if does not specify a background, |bg| is left + unchanged. + + You will often wish to directly use the color |fg| or |bg| after + using this command. For this common situation, the optional argument + \meta{fg or bg} is useful, which may be either |fg| or + |bg|. Giving this option will cause the foreground |fg| or the + background |bg| to be immediately installed after they have been + setup. Thus, the following command +\begin{verbatim} +\usebeamercolor[fg]{normal text} +\end{verbatim} + is a shortcut for +\begin{verbatim} +\usebeamercolor{normal text} +\color{fg} +\end{verbatim} + + If you use the starred version of this command, the \beamer-color + |normal text| is used before the command is invoked. This ensures + that, barring evil trickery, the colors |fg| and |bg| will be setup + independently of whatever colors happened to be in use when the + command is invoked. + + This command has special side-effects. First, the (normal) color + |parent.bg| is set to the value of |bg| prior to this call. Thus you + can access the color that was in use prior to the call of this + command via the color |parent.bg|. + + Second, the special color \meta{beamer-color name}|.fg| is \emph{globally} + set to the same value as |fg| and \meta{beamer-color name}|.bg| is + globally set to the value of |bg|. This allows you to access the + foreground or background of a certain \meta{beamer-color name} after + another \beamer-color has been used. However, referring to these + special global colors should be kept to the unavoidable minimum and + should be done as locally as possible since a change of the + \beamer-color will not reflect in a change of the colors + \meta{beamer-color name}|.fg| and \meta{beamer-color name}|.bg| + until the next invocation of |\usebeamercolor|. Also, if the + \meta{beamer-color name} does not specify a foreground or a + background color, then the values of the special colors are whatever + happened to be the foreground or background at the time of the last + invocation of |\usebeamercolor|. + + So, try not to get into the habit of writing |\color{structure.fg}| + all the time, at least not without a |\usebeamercolor{structure}| + close by. + + \example +\begin{verbatim} + This text is {\usebeamercolor[fg]{alerted text} alerted}. The + following box uses the fore- and background of frametitles: + { + \usebeamercolor[fg]{frametitle} + \colorbox{bg}{Frame Title} + } +\end{verbatim} + + \articlenote + This command has no effect in |article| mode. +\end{command} + + +\begin{command}{\ifbeamercolorempty\oarg{fg or bg}\marg{beamer-color + name}\marg{if undefined}\marg{if defined}} + This command can be used to check whether the foreground or + background of some \meta{beamer-color name} is non-empty. If the + foreground or background of \meta{beamer-color name} is defined, + \meta{if defined} will be executed, otherwise the \meta{if undefined} code. + + \example +\begin{verbatim} +\ifbeamercolorempty[bg]{frametitle} +{ % ``Transparent background'' + \usebeamercolor[fg]{frametitle} + \insertframetitle +} +{ % Opaque background + \usebeamercolor[fg]{frametitle} + \colorbox{bg}{\insertframetitle} +} +\end{verbatim} +\end{command} + + + + +\subsubsection{Setting Beamer's Colors} + +To set or to change a \beamer-color, you can use the command +|\setbeamercolor|. + +\begin{command}{\setbeamercolor\opt{|*|}\marg{beamer-color name}\marg{options}} + Sets or changes a \beamer-color. The \meta{beamer-color name} should + be a reasonably simple text (do not try too much trickery and avoid + punctuation symbols), but it may contain spaces. Thus, |normal text| + is a valid \meta{beamer-color name} and so is |My Color Number 2|. + + In the most simple case, you just specify a foreground by giving the + |fg=| option and, possibly, also a background using the |bg=| + option. + + \example |\setbeamercolor{normal text}{fg=black,bg=mylightgrey}| + \example |\setbeamercolor{alerted text}{fg=red!80!black}| + + The effect of this command is accumulative, thus the following two + commands +\begin{verbatim} +\setbeamercolor{section in toc}{fg=blue} +\setbeamercolor{section in toc}{bg=white} +\end{verbatim} + have the same effect as +\begin{verbatim} +\setbeamercolor{section in toc}{fg=blue,bg=white} +\end{verbatim} + Naturally, a second call with the same kind of \meta{option} set to + a different value overrides a previous call. + + The starred version first resets everything, thereby ``switching + off'' the accumulative effect. Use this starred version to + completely reset the definition of some \beamer-color. + + The following \meta{options} may be given: + \begin{itemize} + \item \declare{|fg=|\meta{color}} sets the foreground color of + \meta{beamer-color name} to the given (normal) \meta{color}. The + \meta{color} may also be a color expression like |red!50!black|, + see the manual of the \textsc{xcolor} package. If \meta{color} + is empty, the \meta{beamer-color name} ``has no special + foreground'' and when the color is used, the foreground + currently in force should not be changed. + + Specifying a foreground this way will override any inherited + foreground color. + \item \declare{|bg=|\meta{color}} does the same as the |fg| + option, but for the background. + \item \declare{|parent=|\meta{parent beamer-color(s)}} specifies + that \meta{beamer-color name} should inherit from the specified + \meta{parent beamer-color(s)}. Any foreground and/or background + color set by the parents will also be used when + \meta{beamer-color name} is used. If multiple parents specify + a foreground, the last one ``wins''; and likewise for the + backgrounds. + + \example +\begin{verbatim} +\setbeamercolor{father}{fg=red} +\setbeamercolor{mother}{bg=green} +\setbeamercolor{child}{parent={father,mother}} +\begin{beamercolorbox}{child} + Terrible red on green text. +\end{beamercolorbox} + +\setbeamercolor{father}{fg=blue} +\begin{beamercolorbox}{child} + Now terrible blue on green text, since parent was changed. +\end{beamercolorbox} +\end{verbatim} + + Note that a change of the foreground or background of a parent + changes the corresponding foreground or background of the child + (unless it is overruled). + + A \beamer-color cannot only have parents, but also grandparents + and so on. + \item \declare{|use=|\meta{another beamer-color}} is used to + make sure that another \beamer-color is setup correctly before the + foreground or background color specification are evaluated. + + Suppose you wish the foreground of items to be a mixture + of 50\% of the foreground of structural elements and 50\% of the + normal foreground color. You could try +\begin{verbatim} +\setbeamercolor{item}{fg=structure.fg!50!normal text.fg} +\end{verbatim} + However, this will not necessarily give the desired result: If + the \beamer-color |structure| changes, the (normal) color + |structure.fg| is not immediately updated. In order to ensure + that the normal color |structure.fg| is correct, use the + following: +\begin{verbatim} +\setbeamercolor{item}{use={structure,normal text},fg=structure.fg!50!normal text.fg} +\end{verbatim} + This will guarantee that the colors |structure.fg| and + |normal text.fg| are setup correctly when the foreground of + |item| is computed. + + To show the difference, consider the following example: +\begin{verbatim} +\setbeamercolor{grandfather}{fg=red} +\setbeamercolor{grandmother}{bg=white} +\setbeamercolor{father}{parent={grandfather,grandmother}} +\setbeamercolor{mother}{fg=black} +{ + \usebeamercolor{father}\usebeamercolor{mother} + %% Defines father.fg and mother.fg globally +} +\setbeamercolor{my color A}{fg=father.fg!50!mother.fg} +\setbeamercolor{my color B}{use={father,mother},fg=father.fg!50!mother.fg} + +{\usebeamercolor[fg]{my color A} dark red text} +{\usebeamercolor[fg]{my color b} also dark red text} + +\setbeamercolor{grandfather}{fg=green} + +{\usebeamercolor[fg]{my color A} still dark red text} +{\usebeamercolor[fg]{my color b} now dark green text} +\end{verbatim} + \end{itemize} +\end{command} + + + + +\subsection{The Color of Mathematical Text} + +By default, mathematical text does not have any special color---it +just inherits the ``surrounding'' color. Some people prefer +mathematical text to have some special color. Though I do not +recommend this (I think mathematical text should \emph{not} stand out +admit the normal text), \beamer\ makes it (reasonably) easy to change +the color of mathematical text. Simply change the following colors: + +\begin{element}{math text}\no\yes\no + This color is the parent of |math text inlined| and + |math text displayed|. It is empty by default. See those colors for + details. +\end{element} + +\begin{element}{math text inlined}\no\yes\no + \colorparents{math text} + If the foreground of this color is set, inlined mathematical text is + typeset using this color. This is done via some |\everymath| hackery + and may not work in all cases. If not, you'll have to try to find a + way around the problem. The background is currently + ignored. +\end{element} + +\begin{element}{math text displayed}\no\yes\no + \colorparents{math text} + Like |math text inlined|, only for so-called ``displayed'' + mathematical text. This is mathematical text between |\[| and |\]| or + between |$$| and |$$| or inside environments like |equation| or + |align|. The setup of this color is somewhat fragile, use at your + own risk. The background is currently + ignored. +\end{element} + +\begin{element}{normal text in math text}\no\yes\no + If the foreground of this color is set, normal text inside + mathematical text (which is introduced using the |\text| command) + will be typeset using this color. The background is currently + ignored. +\end{element} + + + +\subsection{The Color Palettes} + +When one designs a color theme, one faces the following problem: +Suppose we want the colors in the headline to gradually change from +black to, say, blue. Whatever is at the very top of the headline +should be black, what comes right below it should be dark blue, and at +the bottom of the headline things should just be blue. Unfortunately, +different outer themes will put different things at the top. One theme +might put the author at the top, another theme might put the document +title there. This makes it impossible to directly assign one of the +three colors ``black'', ``dark blue,'' and ``blue'' to the different +elements that are typically rendered in the headline. No matter how we +assign them, things will look wrong for certain outer themes. + +To circumvent this problem, \beamer\ uses a layer of \emph{palette +colors}. Color themes typically only change these palette colors. For +example, a color theme might make the \beamer-color |palette primary| +blue, make |palette secondary| a dark blue, and make |palette tertiary| +black. Outer themes can now setup things such that whatever they show +at the top of the headline inherits from |palette tertiary|, what comes +below inherits from |palette secondary|, and whatever is at the bottom +inherits from |palette tertiary|. This way, color themes can change the +way even complicated outer themes look and they can do so +consistently. + +Note that the user can still change the color of every element +individually, simply by overriding the color(s) of the elements in the +headline. In a sense, the palette colors are just a ``suggestion'' how +things should be colored by an outer theme. + +In detail, the following palette colors are used by outer themes. + + +\begin{element}{palette primary}\no\yes\no + Outer themes (should) base the color of navigational elements and, + possibly, also of other elements, on the four palette colors. The + ``primary'' palette should be used for the most important + navigational elements, which are usually the ones that change most + often and hence require the most attention by the audience. The + ``secondary'' and ``tertiary'' are less important, the ``quaternary'' one + is least important. + + By default, the palette colors do not have a background and the + foreground ranges from |structure.fg| to |black|. + + For the sidebar, there is an extra set of palette colors, see + |palette sidebar primary|. +\end{element} + +\begin{element}{palette secondary}\no\yes\no + See |palette primary|. +\end{element} + +\begin{element}{palette tertiary}\no\yes\no + See |palette primary|. +\end{element} + +\begin{element}{palette quaternary}\no\yes\no + See |palette primary|. +\end{element} + +\begin{element}{palette sidebar primary}\no\yes\no + Similar to |palette primary|, only outer themes (should) base the + colors of elements in the sidebar of the four sidebar palette + colors. +\end{element} + +\begin{element}{palette sidebar secondary}\no\yes\no + See |palette sidebar primary|. +\end{element} + +\begin{element}{palette sidebar tertiary}\no\yes\no + See |palette sidebar primary|. +\end{element} + +\begin{element}{palette sidebar quaternary}\no\yes\no + See |palette sidebar primary|. +\end{element} + + + +\subsection{Miscellaneous Colors} + +In this section some ``basic'' colors are listed that do not +``belong'' to any special commands. + +\begin{element}{normal text}\no\yes\yes + The color is used for normal text. At the beginning of + the document the foreground color is installed as + |\normalcolor|. The background of this color is used by the + default background canvas for the background of the + presentation, see Section~\ref{section-canvas}. The background is + also the default value of the normal color |bg|. + + Since the color is the ``root'' of all other \beamer-colors, both a + foreground and a background must be installed. In particular, to get + a transparent background canvas, make the background of the + \beamer-color |background canvas| empty, not the background of this + color. + + The \beamer-font currently is not used. In particular, redefining this + font will not have any effect. This is likely to change in the future. +\end{element} + +\begin{element}{example text}\no\yes\yes + The color/font is used when text is typeset inside an |example| + block. +\end{element} + +\begin{element}{titlelike}\no\yes\yes + This color/font is a more specialized form of the |structure| + color/font. It is the base for all elements that are ``like + titles.'' This includes the frame title and subtitle as well as the + document title and subtitle. +\end{element} + +\begin{element}{separation line}\no\yes\no + The foreground of this color is used for separating lines. If the + foreground is empty, no separation line is drawn. +\end{element} + +\begin{element}{upper separation line head}\no\yes\no + \colorparents{separation line} + Special case for the uppermost separation line in a headline. +\end{element} + +\begin{element}{middle separation line head}\no\yes\no + \colorparents{separation line} + Special case for the middle separation line in a headline. +\end{element} + +\begin{element}{lower separation line head}\no\yes\no + \colorparents{separation line} + Special case for the lower separation line in a headline. +\end{element} + +\begin{element}{upper separation line foot}\no\yes\no + \colorparents{separation line} + Special case for the uppermost separation line in a footline. +\end{element} + +\begin{element}{middle separation line foot}\no\yes\no + \colorparents{separation line} + Special case for the middle separation line in a footline. +\end{element} + +\begin{element}{lower separation line foot}\no\yes\no + \colorparents{separation line} + Special case for the lower separation line in a footline. +\end{element} + + + + +\subsection{Transparency Effects} +\label{section-transparent} + +By default, \emph{covered} items are not shown during a +presentation. Thus if you write |\uncover<2>{Text.}|, the text +is not shown on any but the second slide. On the other slide, the text +is not simply printed using the background color -- it is not shown at +all. This effect is most useful if your background does not have a +uniform color. + +Sometimes however, you might prefer that covered items are not +completely covered. Rather, you would like them to be shown already in +a very dim or shaded way. This allows your audience to get a feeling +for what is yet to come, without getting distracted by it. Also, you +might wish text that is covered ``once more'' still to be visible to +some degree. + +Ideally, there would be an option to make covered text +``transparent.'' This would mean that when covered text is shown, it +would instead be mixed with the background behind it. Unfortunately, +|pgf| does not support real transparency yet. Instead, transparency is +created by mixing the color of the object you want to show with the +current background color (the color |bg|, which has hopefully been +setup such that it is the average color of the background on which the +object should be placed). To install this effect, you can use: +\begin{verbatim} +\setbeamercovered{transparent} +\end{verbatim} +This command allows you to specify in a quite general way how a +covered item should be rendered. You can even specify different ways +of rendering the item depending on how long it will take before this +item is shown or for how long it has already been covered once +more. The transparency effect will automatically apply to all colors, +\emph{except} for the colors in images. For images there is a +workaround, see the documentation of the \pgfname\ package. + +\begin{command}{\setbeamercovered\marg{options}} + This command offers several different options, the most important of + which is |transparent|. All options are internally mapped to the two + options |still covered| and |again covered|. + + In detail, the following \meta{options} may be given: + \begin{itemize} + \item \declare{|invisible|} is the default and causes covered text + to ``completely disappear. + \item \declare{|transparent|}\opt{|=|\meta{opaqueness}} causes + covered text to be typset in a ``transparent'' way. By default, + this means that 85\% of the background color is mixed into all + colors or that the \meta{opaqueness} of the text is 15\%. You can + specify a different \meta{percentage}, where |0| means ``totally + transparent'' and |100| means ``totally opaque.'' + + Unfortunately, this value is kind of ``specific'' to every + projector. What looks good on your screen need not look good + during a presentation. + \item \declare{|dynamic|} Makes all covered text quite transparent, + but in a dynamic way. The longer it will take till the text is + uncovered, the stronger the transparency. + \item \declare{|highly dynamic|} Has the same effect as |dynamic|, + but the effect is stronger. + \item \declare{|still covered=|\meta{not yet list}} specifies how + to render covered items that have not yet been uncovered. The + \meta{not yet list} should be a list of |\opaqueness| commands, + see the description of that command, below. + \example +\begin{verbatim} +\setbeamercovered{% + still covered={\opaqueness<1>{15}\opaqueness<2>{10}\opaqueness<3>{5}\opaqueness<4->{2}}, + again covered={\opaqueness<1->{15}}} +\end{verbatim} + \item \declare{|again covered=|\meta{once more list}} specifies how + to render covered items that have once more been covered, that is, + that had been shown before but are now covered again. + \end{itemize} +\end{command} + +\begin{command}{\opaqueness\ssarg{overlay + specification}\marg{percentage of opaqueness}} + The \meta{overlay specification} specifies on which slides covered + text should have which \meta{percentage of opaqueness}. Unlike + other overlay specifications, this \meta{overlay specification} is a + ``relative'' overlay specification. For example, the specification + ``3'' here means ``things that will be uncovered three slides + ahead,'' respectively ``things that have once more been covered for + three slides.'' More precisely, if an item is uncovered for more + than one slide and then covered once more, only the ``first moment + of uncovering'' is used for the calculation of how long the item has + been covered once more. + + An opaqueness of 100 is fully opaque and 0 is fully + transparent. Currently, since real transparency is not yet + implemented, this command causes all colors to get a mixing of + \meta{percentage of opaqueness} of the current + |bg|. At some future point this command might result in real + transparency. + + The alternate \pgfname\ extension used inside an opaque area is + \meta{percentage of opaqueness}|opaque|. In case of nested calls, + only the innermost opaqueness specification is used. + \example +\begin{verbatim} +\setbeamercovered{still covered={\opaqueness<1->{15}},again covered={\opaqueness<1->{15}}} +\pgfdeclareimage{book}{book} +\pgfdeclareimage{book.!15opaque}{filenameforbooknearlytransparent} +\end{verbatim} + Makes everything that is uncovered in two slides only 15 percent + opaque. +\end{command} + + + + + +%%% Local Variables: +%%% mode: latex +%%% TeX-master: "beameruserguide" +%%% End: |