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#! perl |
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|
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#:META:X_RESOURCE:%.expr:string:background expression |
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#:META:X_RESOURCE:%.border:boolean:respect the terminal border |
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#:META:X_RESOURCE:%.interval:seconds:minimum time between updates |
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|
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=head1 NAME |
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|
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background - manage terminal background |
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|
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=head1 SYNOPSIS |
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|
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urxvt --background-expr 'background expression' |
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--background-border |
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--background-interval seconds |
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|
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=head1 DESCRIPTION |
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|
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This extension manages the terminal background by creating a picture that |
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is behind the text, replacing the normal background colour. |
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|
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It does so by evaluating a Perl expression that I<calculates> the image on |
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the fly, for example, by grabbing the root background or loading a file. |
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|
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While the full power of Perl is available, the operators have been design |
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to be as simple as possible. |
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|
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For example, to load an image and scale it to the window size, you would |
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use: |
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|
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urxvt --background-expr 'scale load "/path/to/mybg.png"' |
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|
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Or specified as a X resource: |
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|
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URxvt.background-expr: scale load "/path/to/mybg.png" |
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|
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=head1 THEORY OF OPERATION |
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|
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At startup, just before the window is mapped for the first time, the |
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expression is evaluated and must yield an image. The image is then |
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extended as necessary to cover the whole terminal window, and is set as a |
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background pixmap. |
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|
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If the image contains an alpha channel, then it will be used as-is in |
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visuals that support alpha channels (for example, for a compositing |
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manager). In other visuals, the terminal background colour will be used to |
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replace any transparency. |
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|
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When the expression relies, directly or indirectly, on the window size, |
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position, the root pixmap, or a timer, then it will be remembered. If not, |
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then it will be removed. |
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|
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If any of the parameters that the expression relies on changes (when the |
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window is moved or resized, its position or size changes; when the root |
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pixmap is replaced by another one the root background changes; or when the |
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timer elapses), then the expression will be evaluated again. |
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|
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For example, an expression such as C<scale load "$HOME/mybg.png"> scales the |
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image to the window size, so it relies on the window size and will |
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be reevaluated each time it is changed, but not when it moves for |
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example. That ensures that the picture always fills the terminal, even |
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after its size changes. |
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|
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=head2 EXPRESSIONS |
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|
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Expressions are normal Perl expressions, in fact, they are Perl blocks - |
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which means you could use multiple lines and statements: |
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|
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again 3600; |
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if (localtime now)[6]) { |
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return scale load "$HOME/weekday.png"; |
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} else { |
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return scale load "$HOME/sunday.png"; |
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} |
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|
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This expression is evaluated once per hour. It will set F<sunday.png> as |
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background on Sundays, and F<weekday.png> on all other days. |
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|
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Fortunately, we expect that most expressions will be much simpler, with |
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little Perl knowledge needed. |
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|
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Basically, you always start with a function that "generates" an image |
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object, such as C<load>, which loads an image from disk, or C<root>, which |
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returns the root window background image: |
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|
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load "$HOME/mypic.png" |
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|
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The path is usually specified as a quoted string (the exact rules can be |
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found in the L<perlop> manpage). The F<$HOME> at the beginning of the |
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string is expanded to the home directory. |
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|
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Then you prepend one or more modifiers or filtering expressions, such as |
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C<scale>: |
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|
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scale load "$HOME/mypic.png" |
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|
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Just like a mathematical expression with functions, you should read these |
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expressions from right to left, as the C<load> is evaluated first, and |
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its result becomes the argument to the C<scale> function. |
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|
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Many operators also allow some parameters preceding the input image |
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that modify its behaviour. For example, C<scale> without any additional |
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arguments scales the image to size of the terminal window. If you specify |
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an additional argument, it uses it as a scale factor (multiply by 100 to |
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get a percentage): |
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|
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scale 2, load "$HOME/mypic.png" |
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|
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This enlarges the image by a factor of 2 (200%). As you can see, C<scale> |
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has now two arguments, the C<200> and the C<load> expression, while |
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C<load> only has one argument. Arguments are separated from each other by |
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commas. |
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|
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Scale also accepts two arguments, which are then separate factors for both |
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horizontal and vertical dimensions. For example, this halves the image |
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width and doubles the image height: |
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|
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scale 0.5, 2, load "$HOME/mypic.png" |
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|
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Other effects than scaling are also readily available, for example, you can |
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tile the image to fill the whole window, instead of resizing it: |
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|
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tile load "$HOME/mypic.png" |
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|
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In fact, images returned by C<load> are in C<tile> mode by default, so the C<tile> operator |
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is kind of superfluous. |
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|
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Another common effect is to mirror the image, so that the same edges touch: |
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|
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mirror load "$HOME/mypic.png" |
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|
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This is also a typical background expression: |
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|
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rootalign root |
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|
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It first takes a snapshot of the screen background image, and then |
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moves it to the upper left corner of the screen - the result is |
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pseudo-transparency, as the image seems to be static while the window is |
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moved around. |
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|
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=head2 CYCLES AND CACHING |
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|
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=head3 C<load> et al. |
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|
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As has been mentioned before, the expression might be evaluated multiple |
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times. Each time the expression is reevaluated, a new cycle is said to |
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have begun. Many operators cache their results till the next cycle. |
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|
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For example, the C<load> operator keeps a copy of the image. If it is |
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asked to load the same image on the next cycle it will not load it again, |
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but return the cached copy. |
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|
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This only works for one cycle though, so as long as you load the same |
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image every time, it will always be cached, but when you load a different |
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image, it will forget about the first one. |
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|
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This allows you to either speed things up by keeping multiple images in |
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memory, or conserve memory by loading images more often. |
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|
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For example, you can keep two images in memory and use a random one like |
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this: |
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|
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my $img1 = load "img1.png"; |
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my $img2 = load "img2.png"; |
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(0.5 > rand) ? $img1 : $img2 |
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|
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Since both images are "loaded" every time the expression is evaluated, |
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they are always kept in memory. Contrast this version: |
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|
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my $path1 = "img1.png"; |
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my $path2 = "img2.png"; |
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load ((0.5 > rand) ? $path1 : $path2) |
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|
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Here, a path is selected randomly, and load is only called for one image, |
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so keeps only one image in memory. If, on the next evaluation, luck |
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decides to use the other path, then it will have to load that image again. |
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|
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=head3 C<once { ... }> |
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|
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Another way to cache expensive operations is to use C<once { ... }>. The |
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C<once> operator takes a block of multiple statements enclosed by C<{}> |
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and evaluates it only.. once, returning any images the last statement |
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returned. Further calls simply produce the values from the cache. |
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|
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This is most useful for expensive operations, such as C<blur>: |
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|
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rootalign once { blur 20, root } |
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|
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This makes a blurred copy of the root background once, and on subsequent |
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calls, just root-aligns it. Since C<blur> is usually quite slow and |
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C<rootalign> is quite fast, this trades extra memory (For the cached |
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blurred pixmap) with speed (blur only needs to be redone when root |
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changes). |
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|
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=head1 REFERENCE |
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|
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=head2 COMMAND LINE SWITCHES |
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|
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=over 4 |
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|
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=item --background-expr perl-expression |
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|
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Specifies the Perl expression to evaluate. |
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|
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=item --background-border |
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|
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By default, the expression creates an image that fills the full window, |
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overwriting borders and any other areas, such as the scrollbar. |
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|
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Specifying this flag changes the behaviour, so that the image only |
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replaces the background of the character area. |
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|
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=item --background-interval seconds |
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|
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Since some operations in the underlying XRender extension can effectively |
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freeze your X-server for prolonged time, this extension enforces a minimum |
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time between updates, which is normally about 0.1 seconds. |
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|
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If you want to do updates more often, you can decrease this safety |
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interval with this switch. |
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|
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=back |
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|
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=cut |
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|
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our %_IMG_CACHE; |
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our $HOME; |
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our ($self, $frame); |
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our ($x, $y, $w, $h); |
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|
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# enforce at least this interval between updates |
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our $MIN_INTERVAL = 6/59.951; |
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|
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{ |
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package urxvt::bgdsl; # background language |
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|
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sub FR_PARENT() { 0 } # parent frame, if any - must be #0 |
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sub FR_CACHE () { 1 } # cached values |
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sub FR_AGAIN () { 2 } # what this expr is sensitive to |
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sub FR_STATE () { 3 } # watchers etc. |
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|
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use List::Util qw(min max sum shuffle); |
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|
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=head2 PROVIDERS/GENERATORS |
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|
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These functions provide an image, by loading it from disk, grabbing it |
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from the root screen or by simply generating it. They are used as starting |
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points to get an image you can play with. |
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|
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=over 4 |
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|
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=item load $path |
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|
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Loads the image at the given C<$path>. The image is set to plane tiling |
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mode. |
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|
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Loaded images will be cached for one cycle, and shared between temrinals |
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running in the same process (e.g. in C<urxvtd>). |
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|
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#=item load_uc $path |
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# |
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#Load uncached - same as load, but does not cache the image. This function |
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#is most useufl if you want to optimise a background expression in some |
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#way. |
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|
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=cut |
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|
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sub load($) { |
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my ($path) = @_; |
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|
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$_IMG_CACHE{$path} || do { |
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my $img = $self->new_img_from_file ($path); |
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Scalar::Util::weaken ($_IMG_CACHE{$path} = $img); |
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$img |
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} |
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} |
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|
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=item root |
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|
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Returns the root window pixmap, that is, hopefully, the background image |
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of your screen. |
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|
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This function makes your expression root sensitive, that means it will be |
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reevaluated when the bg image changes. |
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|
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=cut |
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|
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sub root() { |
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$frame->[FR_AGAIN]{rootpmap} = 1; |
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$self->new_img_from_root |
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} |
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|
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=item solid $colour |
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|
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=item solid $width, $height, $colour |
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|
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Creates a new image and completely fills it with the given colour. The |
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image is set to tiling mode. |
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|
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If C<$width> and C<$height> are omitted, it creates a 1x1 image, which is |
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useful for solid backgrounds or for use in filtering effects. |
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|
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=cut |
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|
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sub solid($;$$) { |
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my $colour = pop; |
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|
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my $img = $self->new_img (urxvt::PictStandardARGB32, 0, 0, $_[0] || 1, $_[1] || 1); |
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$img->fill ($colour); |
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$img |
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} |
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|
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=item clone $img |
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|
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Returns an exact copy of the image. This is useful if you want to have |
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multiple copies of the same image to apply different effects to. |
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|
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=cut |
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|
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sub clone($) { |
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$_[0]->clone |
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} |
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|
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=item merge $img ... |
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|
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Takes any number of images and merges them together, creating a single |
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image containing them all. The tiling mode of the first image is used as |
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the tiling mdoe of the resulting image. |
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|
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This function is called automatically when an expression returns multiple |
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images. |
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|
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=cut |
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|
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sub merge(@) { |
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return $_[0] unless $#_; |
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|
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# rather annoyingly clumsy, but optimisation is for another time |
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|
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my $x0 = +1e9; |
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my $y0 = +1e9; |
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my $x1 = -1e9; |
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my $y1 = -1e9; |
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|
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for (@_) { |
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my ($x, $y, $w, $h) = $_->geometry; |
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|
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$x0 = $x if $x0 > $x; |
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$y0 = $y if $y0 > $y; |
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|
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$x += $w; |
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$y += $h; |
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|
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$x1 = $x if $x1 < $x; |
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$y1 = $y if $y1 < $y; |
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} |
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|
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my $base = $self->new_img (urxvt::PictStandardARGB32, $x0, $y0, $x1 - $x0, $y1 - $y0); |
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$base->repeat_mode ($_[0]->repeat_mode); |
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$base->fill ([0, 0, 0, 0]); |
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|
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$base->draw ($_) |
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for @_; |
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|
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$base |
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} |
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|
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=head2 TILING MODES |
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|
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The following operators modify the tiling mode of an image, that is, the |
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way that pixels outside the image area are painted when the image is used. |
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|
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=over 4 |
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|
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=item tile $img |
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|
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Tiles the whole plane with the image and returns this new image - or in |
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other words, it returns a copy of the image in plane tiling mode. |
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|
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Example: load an image and tile it over the background, without |
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resizing. The C<tile> call is superfluous because C<load> already defaults |
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to tiling mode. |
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|
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tile load "mybg.png" |
385 |
|
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=item mirror $img |
387 |
|
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Similar to tile, but reflects the image each time it uses a new copy, so |
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that top edges always touch top edges, right edges always touch right |
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edges and so on (with normal tiling, left edges always touch right edges |
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and top always touch bottom edges). |
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|
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Example: load an image and mirror it over the background, avoiding sharp |
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edges at the image borders at the expense of mirroring the image itself |
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|
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mirror load "mybg.png" |
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|
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=item pad $img |
399 |
|
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Takes an image and modifies it so that all pixels outside the image area |
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become transparent. This mode is most useful when you want to place an |
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image over another image or the background colour while leaving all |
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background pixels outside the image unchanged. |
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|
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Example: load an image and display it in the upper left corner. The rest |
406 |
of the space is left "empty" (transparent or whatever your compositor does |
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in alpha mode, else background colour). |
408 |
|
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pad load "mybg.png" |
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|
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=item extend $img |
412 |
|
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Extends the image over the whole plane, using the closest pixel in the |
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area outside the image. This mode is mostly useful when you use more complex |
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filtering operations and want the pixels outside the image to have the |
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same values as the pixels near the edge. |
417 |
|
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Example: just for curiosity, how does this pixel extension stuff work? |
419 |
|
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extend move 50, 50, load "mybg.png" |
421 |
|
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=cut |
423 |
|
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sub pad($) { |
425 |
my $img = $_[0]->clone; |
426 |
$img->repeat_mode (urxvt::RepeatNone); |
427 |
$img |
428 |
} |
429 |
|
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sub tile($) { |
431 |
my $img = $_[0]->clone; |
432 |
$img->repeat_mode (urxvt::RepeatNormal); |
433 |
$img |
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} |
435 |
|
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sub mirror($) { |
437 |
my $img = $_[0]->clone; |
438 |
$img->repeat_mode (urxvt::RepeatReflect); |
439 |
$img |
440 |
} |
441 |
|
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sub extend($) { |
443 |
my $img = $_[0]->clone; |
444 |
$img->repeat_mode (urxvt::RepeatPad); |
445 |
$img |
446 |
} |
447 |
|
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=back |
449 |
|
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=head2 VARIABLE VALUES |
451 |
|
452 |
The following functions provide variable data such as the terminal window |
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dimensions. They are not (Perl-) variables, they just return stuff that |
454 |
varies. Most of them make your expression sensitive to some events, for |
455 |
example using C<TW> (terminal width) means your expression is evaluated |
456 |
again when the terminal is resized. |
457 |
|
458 |
=over 4 |
459 |
|
460 |
=item TX |
461 |
|
462 |
=item TY |
463 |
|
464 |
Return the X and Y coordinates of the terminal window (the terminal |
465 |
window is the full window by default, and the character area only when in |
466 |
border-respect mode). |
467 |
|
468 |
Using these functions make your expression sensitive to window moves. |
469 |
|
470 |
These functions are mainly useful to align images to the root window. |
471 |
|
472 |
Example: load an image and align it so it looks as if anchored to the |
473 |
background. |
474 |
|
475 |
move -TX, -TY, load "mybg.png" |
476 |
|
477 |
=item TW |
478 |
|
479 |
Return the width (C<TW>) and height (C<TH>) of the terminal window (the |
480 |
terminal window is the full window by default, and the character area only |
481 |
when in border-respect mode). |
482 |
|
483 |
Using these functions make your expression sensitive to window resizes. |
484 |
|
485 |
These functions are mainly useful to scale images, or to clip images to |
486 |
the window size to conserve memory. |
487 |
|
488 |
Example: take the screen background, clip it to the window size, blur it a |
489 |
bit, align it to the window position and use it as background. |
490 |
|
491 |
clip move -TX, -TY, once { blur 5, root } |
492 |
|
493 |
=cut |
494 |
|
495 |
sub TX() { $frame->[FR_AGAIN]{position} = 1; $x } |
496 |
sub TY() { $frame->[FR_AGAIN]{position} = 1; $y } |
497 |
sub TW() { $frame->[FR_AGAIN]{size} = 1; $w } |
498 |
sub TH() { $frame->[FR_AGAIN]{size} = 1; $h } |
499 |
|
500 |
=item now |
501 |
|
502 |
Returns the current time as (fractional) seconds since the epoch. |
503 |
|
504 |
Using this expression does I<not> make your expression sensitive to time, |
505 |
but the next two functions do. |
506 |
|
507 |
=item again $seconds |
508 |
|
509 |
When this function is used the expression will be reevaluated again in |
510 |
C<$seconds> seconds. |
511 |
|
512 |
Example: load some image and rotate it according to the time of day (as if it were |
513 |
the hour pointer of a clock). Update this image every minute. |
514 |
|
515 |
again 60; rotate 50, 50, (now % 86400) * -720 / 86400, scale load "myclock.png" |
516 |
|
517 |
=item counter $seconds |
518 |
|
519 |
Like C<again>, but also returns an increasing counter value, starting at |
520 |
0, which might be useful for some simple animation effects. |
521 |
|
522 |
=cut |
523 |
|
524 |
sub now() { urxvt::NOW } |
525 |
|
526 |
sub again($) { |
527 |
$frame->[FR_AGAIN]{time} = $_[0]; |
528 |
} |
529 |
|
530 |
sub counter($) { |
531 |
$frame->[FR_AGAIN]{time} = $_[0]; |
532 |
$frame->[FR_STATE]{counter} + 0 |
533 |
} |
534 |
|
535 |
=back |
536 |
|
537 |
=head2 SHAPE CHANGING OPERATORS |
538 |
|
539 |
The following operators modify the shape, size or position of the image. |
540 |
|
541 |
=over 4 |
542 |
|
543 |
=item clip $img |
544 |
|
545 |
=item clip $width, $height, $img |
546 |
|
547 |
=item clip $x, $y, $width, $height, $img |
548 |
|
549 |
Clips an image to the given rectangle. If the rectangle is outside the |
550 |
image area (e.g. when C<$x> or C<$y> are negative) or the rectangle is |
551 |
larger than the image, then the tiling mode defines how the extra pixels |
552 |
will be filled. |
553 |
|
554 |
If C<$x> an C<$y> are missing, then C<0> is assumed for both. |
555 |
|
556 |
If C<$width> and C<$height> are missing, then the window size will be |
557 |
assumed. |
558 |
|
559 |
Example: load an image, blur it, and clip it to the window size to save |
560 |
memory. |
561 |
|
562 |
clip blur 10, load "mybg.png" |
563 |
|
564 |
=cut |
565 |
|
566 |
sub clip($;$$;$$) { |
567 |
my $img = pop; |
568 |
my $h = pop || TH; |
569 |
my $w = pop || TW; |
570 |
$img->sub_rect ($_[0], $_[1], $w, $h) |
571 |
} |
572 |
|
573 |
=item scale $img |
574 |
|
575 |
=item scale $size_factor, $img |
576 |
|
577 |
=item scale $width_factor, $height_factor, $img |
578 |
|
579 |
Scales the image by the given factors in horizontal |
580 |
(C<$width>) and vertical (C<$height>) direction. |
581 |
|
582 |
If only one factor is give, it is used for both directions. |
583 |
|
584 |
If no factors are given, scales the image to the window size without |
585 |
keeping aspect. |
586 |
|
587 |
=item resize $width, $height, $img |
588 |
|
589 |
Resizes the image to exactly C<$width> times C<$height> pixels. |
590 |
|
591 |
=item fit $img |
592 |
|
593 |
=item fit $width, $height, $img |
594 |
|
595 |
Fits the image into the given C<$width> and C<$height> without changing |
596 |
aspect, or the terminal size. That means it will be shrunk or grown until |
597 |
the whole image fits into the given area, possibly leaving borders. |
598 |
|
599 |
=item cover $img |
600 |
|
601 |
=item cover $width, $height, $img |
602 |
|
603 |
Similar to C<fit>, but shrinks or grows until all of the area is covered |
604 |
by the image, so instead of potentially leaving borders, it will cut off |
605 |
image data that doesn't fit. |
606 |
|
607 |
=cut |
608 |
|
609 |
sub scale($;$;$) { |
610 |
my $img = pop; |
611 |
|
612 |
@_ == 2 ? $img->scale ($_[0] * $img->w, $_[1] * $img->h) |
613 |
: @_ ? $img->scale ($_[0] * $img->w, $_[0] * $img->h) |
614 |
: $img->scale (TW, TH) |
615 |
} |
616 |
|
617 |
sub resize($$$) { |
618 |
my $img = pop; |
619 |
$img->scale ($_[0], $_[1]) |
620 |
} |
621 |
|
622 |
sub fit($;$$) { |
623 |
my $img = pop; |
624 |
my $w = ($_[0] || TW) / $img->w; |
625 |
my $h = ($_[1] || TH) / $img->h; |
626 |
scale +(min $w, $h), $img |
627 |
} |
628 |
|
629 |
sub cover($;$$) { |
630 |
my $img = pop; |
631 |
my $w = ($_[0] || TW) / $img->w; |
632 |
my $h = ($_[1] || TH) / $img->h; |
633 |
scale +(max $w, $h), $img |
634 |
} |
635 |
|
636 |
=item move $dx, $dy, $img |
637 |
|
638 |
Moves the image by C<$dx> pixels in the horizontal, and C<$dy> pixels in |
639 |
the vertical. |
640 |
|
641 |
Example: move the image right by 20 pixels and down by 30. |
642 |
|
643 |
move 20, 30, ... |
644 |
|
645 |
=item align $xalign, $yalign, $img |
646 |
|
647 |
Aligns the image according to a factor - C<0> means the image is moved to |
648 |
the left or top edge (for C<$xalign> or C<$yalign>), C<0.5> means it is |
649 |
exactly centered and C<1> means it touches the right or bottom edge. |
650 |
|
651 |
Example: remove any visible border around an image, center it vertically but move |
652 |
it to the right hand side. |
653 |
|
654 |
align 1, 0.5, pad $img |
655 |
|
656 |
=item center $img |
657 |
|
658 |
=item center $width, $height, $img |
659 |
|
660 |
Centers the image, i.e. the center of the image is moved to the center of |
661 |
the terminal window (or the box specified by C<$width> and C<$height> if |
662 |
given). |
663 |
|
664 |
Example: load an image and center it. |
665 |
|
666 |
center pad load "mybg.png" |
667 |
|
668 |
=item rootalign $img |
669 |
|
670 |
Moves the image so that it appears glued to the screen as opposed to the |
671 |
window. This gives the illusion of a larger area behind the window. It is |
672 |
exactly equivalent to C<move -TX, -TY>, that is, it moves the image to the |
673 |
top left of the screen. |
674 |
|
675 |
Example: load a background image, put it in mirror mode and root align it. |
676 |
|
677 |
rootalign mirror load "mybg.png" |
678 |
|
679 |
Example: take the screen background and align it, giving the illusion of |
680 |
transparency as long as the window isn't in front of other windows. |
681 |
|
682 |
rootalign root |
683 |
|
684 |
=cut |
685 |
|
686 |
sub move($$;$) { |
687 |
my $img = pop->clone; |
688 |
$img->move ($_[0], $_[1]); |
689 |
$img |
690 |
} |
691 |
|
692 |
sub align($;$$) { |
693 |
my $img = pop; |
694 |
|
695 |
move $_[0] * (TW - $img->w), |
696 |
$_[1] * (TH - $img->h), |
697 |
$img |
698 |
} |
699 |
|
700 |
sub center($;$$) { |
701 |
my $img = pop; |
702 |
my $w = $_[0] || TW; |
703 |
my $h = $_[1] || TH; |
704 |
|
705 |
move 0.5 * ($w - $img->w), 0.5 * ($h - $img->h), $img |
706 |
} |
707 |
|
708 |
sub rootalign($) { |
709 |
move -TX, -TY, $_[0] |
710 |
} |
711 |
|
712 |
=item rotate $center_x, $center_y, $degrees |
713 |
|
714 |
Rotates the image by C<$degrees> degrees, counter-clockwise, around the |
715 |
pointer at C<$center_x> and C<$center_y> (specified as factor of image |
716 |
width/height). |
717 |
|
718 |
#TODO# new width, height, maybe more operators? |
719 |
|
720 |
Example: rotate the image by 90 degrees |
721 |
|
722 |
=cut |
723 |
|
724 |
sub rotate($$$$) { |
725 |
my $img = pop; |
726 |
$img->rotate ( |
727 |
$_[0] * ($img->w + $img->x), |
728 |
$_[1] * ($img->h + $img->y), |
729 |
$_[2] * (3.14159265 / 180), |
730 |
) |
731 |
} |
732 |
|
733 |
=back |
734 |
|
735 |
=head2 COLOUR MODIFICATIONS |
736 |
|
737 |
The following operators change the pixels of the image. |
738 |
|
739 |
=over 4 |
740 |
|
741 |
=item contrast $factor, $img |
742 |
|
743 |
=item contrast $r, $g, $b, $img |
744 |
|
745 |
=item contrast $r, $g, $b, $a, $img |
746 |
|
747 |
Adjusts the I<contrast> of an image. |
748 |
|
749 |
The first form applies a single C<$factor> to red, green and blue, the |
750 |
second form applies separate factors to each colour channel, and the last |
751 |
form includes the alpha channel. |
752 |
|
753 |
Values from 0 to 1 lower the contrast, values higher than 1 increase the |
754 |
contrast. |
755 |
|
756 |
Due to limitations in the underlying XRender extension, lowering contrast |
757 |
also reduces brightness, while increasing contrast currently also |
758 |
increases brightness. |
759 |
|
760 |
=item brightness $bias, $img |
761 |
|
762 |
=item brightness $r, $g, $b, $img |
763 |
|
764 |
=item brightness $r, $g, $b, $a, $img |
765 |
|
766 |
Adjusts the brightness of an image. |
767 |
|
768 |
The first form applies a single C<$bias> to red, green and blue, the |
769 |
second form applies separate biases to each colour channel, and the last |
770 |
form includes the alpha channel. |
771 |
|
772 |
Values less than 0 reduce brightness, while values larger than 0 increase |
773 |
it. Useful range is from -1 to 1 - the former results in a black, the |
774 |
latter in a white picture. |
775 |
|
776 |
Due to idiosyncrasies in the underlying XRender extension, biases less |
777 |
than zero can be I<very> slow. |
778 |
|
779 |
=cut |
780 |
|
781 |
sub contrast($$;$$;$) { |
782 |
my $img = pop; |
783 |
my ($r, $g, $b, $a) = @_; |
784 |
|
785 |
($g, $b) = ($r, $r) if @_ < 3; |
786 |
$a = 1 if @_ < 4; |
787 |
|
788 |
$img = $img->clone; |
789 |
$img->contrast ($r, $g, $b, $a); |
790 |
$img |
791 |
} |
792 |
|
793 |
sub brightness($$;$$;$) { |
794 |
my $img = pop; |
795 |
my ($r, $g, $b, $a) = @_; |
796 |
|
797 |
($g, $b) = ($r, $r) if @_ < 3; |
798 |
$a = 1 if @_ < 4; |
799 |
|
800 |
$img = $img->clone; |
801 |
$img->brightness ($r, $g, $b, $a); |
802 |
$img |
803 |
} |
804 |
|
805 |
=item blur $radius, $img |
806 |
|
807 |
=item blur $radius_horz, $radius_vert, $img |
808 |
|
809 |
Gaussian-blurs the image with (roughly) C<$radius> pixel radius. The radii |
810 |
can also be specified separately. |
811 |
|
812 |
Blurring is often I<very> slow, at least compared or other |
813 |
operators. Larger blur radii are slower than smaller ones, too, so if you |
814 |
don't want to freeze your screen for long times, start experimenting with |
815 |
low values for radius (<5). |
816 |
|
817 |
=cut |
818 |
|
819 |
sub blur($$;$) { |
820 |
my $img = pop; |
821 |
$img->blur ($_[0], @_ >= 2 ? $_[1] : $_[0]) |
822 |
} |
823 |
|
824 |
=back |
825 |
|
826 |
=head2 OTHER STUFF |
827 |
|
828 |
Anything that didn't fit any of the other categories, even after applying |
829 |
force and closing our eyes. |
830 |
|
831 |
=over 4 |
832 |
|
833 |
=item once { ... } |
834 |
|
835 |
This function takes a code block as argument, that is, one or more |
836 |
statements enclosed by braces. |
837 |
|
838 |
The trick is that this code block is only evaluated once - future calls |
839 |
will simply return the original image (yes, it should only be used with |
840 |
images). |
841 |
|
842 |
This can be extremely useful to avoid redoing the same slow operations |
843 |
again and again- for example, if your background expression takes the root |
844 |
background, blurs it and then root-aligns it it would have to blur the |
845 |
root background on every window move or resize. |
846 |
|
847 |
In fact, urxvt itself encloses the whole expression in some kind of |
848 |
C<once> block so it only is reevaluated as required. |
849 |
|
850 |
Putting the blur into a C<once> block will make sure the blur is only done |
851 |
once: |
852 |
|
853 |
rootlign once { blur 10, root } |
854 |
|
855 |
This leaves the question of how to force reevaluation of the block, |
856 |
in case the root background changes: If expression inside the block |
857 |
is sensitive to some event (root background changes, window geometry |
858 |
changes), then it will be reevaluated automatically as needed. |
859 |
|
860 |
=item once_again |
861 |
|
862 |
Resets all C<once> block as if they had never been called, i.e. on the |
863 |
next call they will be reevaluated again. |
864 |
|
865 |
=cut |
866 |
|
867 |
sub once(&) { |
868 |
my $id = $_[0]+0; |
869 |
|
870 |
local $frame = $self->{frame_cache}{$id} ||= [$frame]; |
871 |
|
872 |
unless ($frame->[FR_CACHE]) { |
873 |
$frame->[FR_CACHE] = [ $_[0]() ]; |
874 |
|
875 |
my $self = $self; |
876 |
my $frame = $frame; |
877 |
Scalar::Util::weaken $frame; |
878 |
$self->compile_frame ($frame, sub { |
879 |
# clear this frame cache, also for all parents |
880 |
for (my $frame = $frame; $frame; $frame = $frame->[0]) { |
881 |
undef $frame->[FR_CACHE]; |
882 |
} |
883 |
|
884 |
unless ($self->{term}) { |
885 |
use Data::Dump; |
886 |
ddx $frame; |
887 |
exit; |
888 |
} |
889 |
|
890 |
$self->recalculate; |
891 |
}); |
892 |
}; |
893 |
|
894 |
# in scalar context we always return the first original result, which |
895 |
# is not quite how perl works. |
896 |
wantarray |
897 |
? @{ $frame->[FR_CACHE] } |
898 |
: $frame->[FR_CACHE][0] |
899 |
} |
900 |
|
901 |
sub once_again() { |
902 |
delete $self->{frame_cache}; |
903 |
} |
904 |
|
905 |
=back |
906 |
|
907 |
=cut |
908 |
|
909 |
} |
910 |
|
911 |
sub parse_expr { |
912 |
my $expr = eval |
913 |
"sub {\n" |
914 |
. "package urxvt::bgdsl;\n" |
915 |
. "#line 0 'background expression'\n" |
916 |
. "$_[0]\n" |
917 |
. "}"; |
918 |
die if $@; |
919 |
$expr |
920 |
} |
921 |
|
922 |
# compiles a parsed expression |
923 |
sub set_expr { |
924 |
my ($self, $expr) = @_; |
925 |
|
926 |
$self->{root} = []; |
927 |
$self->{expr} = $expr; |
928 |
$self->recalculate; |
929 |
} |
930 |
|
931 |
# takes a hash of sensitivity indicators and installs watchers |
932 |
sub compile_frame { |
933 |
my ($self, $frame, $cb) = @_; |
934 |
|
935 |
my $state = $frame->[urxvt::bgdsl::FR_STATE] ||= {}; |
936 |
my $again = $frame->[urxvt::bgdsl::FR_AGAIN]; |
937 |
|
938 |
# don't keep stuff alive |
939 |
Scalar::Util::weaken $state; |
940 |
|
941 |
if ($again->{nested}) { |
942 |
$state->{nested} = 1; |
943 |
} else { |
944 |
delete $state->{nested}; |
945 |
} |
946 |
|
947 |
if (my $interval = $again->{time}) { |
948 |
$state->{time} = [$interval, urxvt::timer->new->after ($interval)->interval ($interval)] |
949 |
if $state->{time}[0] != $interval; |
950 |
|
951 |
# callback *might* have changed, although we could just rule that out |
952 |
$state->{time}[1]->cb (sub { |
953 |
++$state->{counter}; |
954 |
$cb->(); |
955 |
}); |
956 |
} else { |
957 |
delete $state->{time}; |
958 |
} |
959 |
|
960 |
if ($again->{position}) { |
961 |
$state->{position} = $self->on (position_change => $cb); |
962 |
} else { |
963 |
delete $state->{position}; |
964 |
} |
965 |
|
966 |
if ($again->{size}) { |
967 |
$state->{size} = $self->on (size_change => $cb); |
968 |
} else { |
969 |
delete $state->{size}; |
970 |
} |
971 |
|
972 |
if ($again->{rootpmap}) { |
973 |
$state->{rootpmap} = $self->on (rootpmap_change => $cb); |
974 |
} else { |
975 |
delete $state->{rootpmap}; |
976 |
} |
977 |
} |
978 |
|
979 |
# evaluate the current bg expression |
980 |
sub recalculate { |
981 |
my ($arg_self) = @_; |
982 |
|
983 |
# rate limit evaluation |
984 |
|
985 |
if ($arg_self->{next_refresh} > urxvt::NOW) { |
986 |
$arg_self->{next_refresh_timer} = urxvt::timer->new->after ($arg_self->{next_refresh} - urxvt::NOW)->cb (sub { |
987 |
$arg_self->recalculate; |
988 |
}); |
989 |
return; |
990 |
} |
991 |
|
992 |
$arg_self->{next_refresh} = urxvt::NOW + $MIN_INTERVAL; |
993 |
|
994 |
# set environment to evaluate user expression |
995 |
|
996 |
local $self = $arg_self; |
997 |
local $HOME = $ENV{HOME}; |
998 |
local $frame = []; |
999 |
|
1000 |
($x, $y, $w, $h) = $self->background_geometry ($self->{border}); |
1001 |
|
1002 |
# evaluate user expression |
1003 |
|
1004 |
my @img = eval { $self->{expr}->() }; |
1005 |
die $@ if $@; |
1006 |
die "background-expr did not return anything.\n" unless @img; |
1007 |
die "background-expr: expected image(s), got something else.\n" |
1008 |
if grep { !UNIVERSAL::isa $_, "urxvt::img" } @img; |
1009 |
|
1010 |
my $img = urxvt::bgdsl::merge @img; |
1011 |
|
1012 |
$frame->[FR_AGAIN]{size} = 1 |
1013 |
if $img->repeat_mode != urxvt::RepeatNormal; |
1014 |
|
1015 |
# if the expression is sensitive to external events, prepare reevaluation then |
1016 |
$self->compile_frame ($frame, sub { $arg_self->recalculate }); |
1017 |
|
1018 |
# clear stuff we no longer need |
1019 |
|
1020 |
# unless (%{ $frame->[FR_STATE] }) { |
1021 |
# delete $self->{state}; |
1022 |
# delete $self->{expr}; |
1023 |
# } |
1024 |
|
1025 |
# set background pixmap |
1026 |
|
1027 |
$self->set_background ($img, $self->{border}); |
1028 |
$self->scr_recolour (0); |
1029 |
$self->want_refresh; |
1030 |
} |
1031 |
|
1032 |
sub on_start { |
1033 |
my ($self) = @_; |
1034 |
|
1035 |
my $expr = $self->x_resource ("%.expr") |
1036 |
or return; |
1037 |
|
1038 |
$self->has_render |
1039 |
or die "background extension needs RENDER extension 0.10 or higher, ignoring background-expr.\n"; |
1040 |
|
1041 |
$self->set_expr (parse_expr $expr); |
1042 |
$self->{border} = $self->x_resource_boolean ("%.border"); |
1043 |
|
1044 |
$MIN_INTERVAL = $self->x_resource ("%.interval"); |
1045 |
|
1046 |
() |
1047 |
} |
1048 |
|