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Comparing rxvt-unicode/src/perl/background (file contents):
Revision 1.49 by root, Sun Jun 10 15:29:18 2012 UTC vs.
Revision 1.53 by root, Tue Jun 12 18:25:57 2012 UTC

1#! perl 1#! perl
2 2
3#:META:X_RESOURCE:%.expr:string:background expression 3#:META:X_RESOURCE:%.expr:string:background expression
4#:META:X_RESOURCE:%.border:boolean:respect the terminal border 4#:META:X_RESOURCE:%.border:boolean:respect the terminal border
5#:META:X_RESOURCE:%.interval:seconds:minimum time between updates 5#:META:X_RESOURCE:%.interval:seconds:minimum time between updates
6
7#TODO: once, rootalign
8 6
9=head1 NAME 7=head1 NAME
10 8
11 background - manage terminal background 9 background - manage terminal background
12 10
… …
59 57
60For example, an expression such as C<scale load "$HOME/mybg.png"> scales the 58For example, an expression such as C<scale load "$HOME/mybg.png"> scales the
61image to the window size, so it relies on the window size and will 59image to the window size, so it relies on the window size and will
62be reevaluated each time it is changed, but not when it moves for 60be reevaluated each time it is changed, but not when it moves for
63example. That ensures that the picture always fills the terminal, even 61example. That ensures that the picture always fills the terminal, even
64after it's size changes. 62after its size changes.
65 63
66=head2 EXPRESSIONS 64=head2 EXPRESSIONS
67 65
68Expressions are normal Perl expressions, in fact, they are Perl blocks - 66Expressions are normal Perl expressions, in fact, they are Perl blocks -
69which means you could use multiple lines and statements: 67which means you could use multiple lines and statements:
… …
117horizontal and vertical dimensions. For example, this halves the image 115horizontal and vertical dimensions. For example, this halves the image
118width and doubles the image height: 116width and doubles the image height:
119 117
120 scale 0.5, 2, load "$HOME/mypic.png" 118 scale 0.5, 2, load "$HOME/mypic.png"
121 119
122Other effects than scalign are also readily available, for exmaple, you can 120Other effects than scaling are also readily available, for example, you can
123tile the image to fill the whole window, instead of resizing it: 121tile the image to fill the whole window, instead of resizing it:
124 122
125 tile load "$HOME/mypic.png" 123 tile load "$HOME/mypic.png"
126 124
127In fact, images returned by C<load> are in C<tile> mode by default, so the C<tile> operator 125In fact, images returned by C<load> are in C<tile> mode by default, so the C<tile> operator
… …
153This only works for one cycle though, so as long as you load the same 151This only works for one cycle though, so as long as you load the same
154image every time, it will always be cached, but when you load a different 152image every time, it will always be cached, but when you load a different
155image, it will forget about the first one. 153image, it will forget about the first one.
156 154
157This allows you to either speed things up by keeping multiple images in 155This allows you to either speed things up by keeping multiple images in
158memory, or comserve memory by loading images more often. 156memory, or conserve memory by loading images more often.
159 157
160For example, you can keep two images in memory and use a random one like 158For example, you can keep two images in memory and use a random one like
161this: 159this:
162 160
163 my $img1 = load "img1.png"; 161 my $img1 = load "img1.png";
… …
193Specifying this flag changes the behaviour, so that the image only 191Specifying this flag changes the behaviour, so that the image only
194replaces the background of the character area. 192replaces the background of the character area.
195 193
196=item --background-interval seconds 194=item --background-interval seconds
197 195
198Since some operations in the underlying XRender extension can effetively 196Since some operations in the underlying XRender extension can effectively
199freeze your X-server for prolonged time, this extension enforces a minimum 197freeze your X-server for prolonged time, this extension enforces a minimum
200time between updates, which is normally about 0.1 seconds. 198time between updates, which is normally about 0.1 seconds.
201 199
202If you want to do updates more often, you can decrease this safety 200If you want to do updates more often, you can decrease this safety
203interval with this switch. 201interval with this switch.
204 202
205=back 203=back
206 204
207=cut 205=cut
208 206
209our %_IMGCACHE; 207our %_IMG_CACHE;
208our %_ONCE_CACHE;
210our $HOME; 209our $HOME;
211our ($self, $old, $new); 210our ($self, $old, $new);
212our ($x, $y, $w, $h); 211our ($x, $y, $w, $h);
213 212
214# enforce at least this interval between updates 213# enforce at least this interval between updates
… …
252 251
253=cut 252=cut
254 253
255 sub root() { 254 sub root() {
256 $new->{rootpmap_sensitive} = 1; 255 $new->{rootpmap_sensitive} = 1;
257 die "root op not supported, exg, we need you"; 256 $self->new_img_from_root
258 } 257 }
259 258
260=item solid $colour 259=item solid $colour
261 260
262=item solid $width, $height, $colour 261=item solid $width, $height, $colour
… …
285=cut 284=cut
286 285
287 sub clone($) { 286 sub clone($) {
288 $_[0]->clone 287 $_[0]->clone
289 } 288 }
290
291=back
292 289
293=head2 TILING MODES 290=head2 TILING MODES
294 291
295The following operators modify the tiling mode of an image, that is, the 292The following operators modify the tiling mode of an image, that is, the
296way that pixels outside the image area are painted when the image is used. 293way that pixels outside the image area are painted when the image is used.
… …
326become transparent. This mode is most useful when you want to place an 323become transparent. This mode is most useful when you want to place an
327image over another image or the background colour while leaving all 324image over another image or the background colour while leaving all
328background pixels outside the image unchanged. 325background pixels outside the image unchanged.
329 326
330Example: load an image and display it in the upper left corner. The rest 327Example: load an image and display it in the upper left corner. The rest
331of the space is left "empty" (transparent or wahtever your compisotr does 328of the space is left "empty" (transparent or whatever your compositor does
332in alpha mode, else background colour). 329in alpha mode, else background colour).
333 330
334 pad load "mybg.png" 331 pad load "mybg.png"
335 332
336=item extend $img 333=item extend $img
337 334
338Extends the image over the whole plane, using the closest pixel in the 335Extends the image over the whole plane, using the closest pixel in the
339area outside the image. This mode is mostly useful when you more complex 336area outside the image. This mode is mostly useful when you use more complex
340filtering operations and want the pixels outside the image to have the 337filtering operations and want the pixels outside the image to have the
341same values as the pixels near the edge. 338same values as the pixels near the edge.
342 339
343Example: just for curiosity, how does this pixel extension stuff work? 340Example: just for curiosity, how does this pixel extension stuff work?
344 341
… …
435C<$seconds> seconds. 432C<$seconds> seconds.
436 433
437Example: load some image and rotate it according to the time of day (as if it were 434Example: load some image and rotate it according to the time of day (as if it were
438the hour pointer of a clock). Update this image every minute. 435the hour pointer of a clock). Update this image every minute.
439 436
440 again 60; rotate TW, TH, 50, 50, (now % 86400) * -720 / 86400, scale load "myclock.png" 437 again 60; rotate 50, 50, (now % 86400) * -720 / 86400, scale load "myclock.png"
441 438
442=item counter $seconds 439=item counter $seconds
443 440
444Like C<again>, but also returns an increasing counter value, starting at 441Like C<again>, but also returns an increasing counter value, starting at
4450, which might be useful for some simple animation effects. 4420, which might be useful for some simple animation effects.
… …
632 629
633 sub rootalign($) { 630 sub rootalign($) {
634 move -TX, -TY, $_[0] 631 move -TX, -TY, $_[0]
635 } 632 }
636 633
634=item rotate $center_x, $center_y, $degrees
635
636Rotates the image by C<$degrees> degrees, counter-clockwise, around the
637pointer at C<$center_x> and C<$center_y> (specified as factor of image
638width/height).
639
640#TODO# new width, height, maybe more operators?
641
642Example: rotate the image by 90 degrees
643
644=cut
645
646 sub rotate($$$$) {
647 my $img = pop;
648 $img->rotate (
649 $_[0] * $img->w,
650 $_[1] * $img->h,
651 $_[2] * (3.14159265 / 180),
652 )
653 }
654
637=back 655=back
638 656
639=head2 COLOUR MODIFICATIONS 657=head2 COLOUR MODIFICATIONS
640 658
641The following operators change the pixels of the image. 659The following operators change the pixels of the image.
… …
675 693
676Values less than 0 reduce brightness, while values larger than 0 increase 694Values less than 0 reduce brightness, while values larger than 0 increase
677it. Useful range is from -1 to 1 - the former results in a black, the 695it. Useful range is from -1 to 1 - the former results in a black, the
678latter in a white picture. 696latter in a white picture.
679 697
680Due to idiosynchrasies in the underlying XRender extension, biases less 698Due to idiosyncrasies in the underlying XRender extension, biases less
681than zero can be I<very> slow. 699than zero can be I<very> slow.
682 700
683=cut 701=cut
684 702
685 sub contrast($$;$$;$) { 703 sub contrast($$;$$;$) {
… …
723 sub blur($$;$) { 741 sub blur($$;$) {
724 my $img = pop; 742 my $img = pop;
725 $img->blur ($_[0], @_ >= 2 ? $_[1] : $_[0]) 743 $img->blur ($_[0], @_ >= 2 ? $_[1] : $_[0])
726 } 744 }
727 745
728=item rotate $new_width, $new_height, $center_x, $center_y, $degrees 746=back
729 747
730Rotates the image by C<$degrees> degrees, counter-clockwise, around the 748=head2 OTHER STUFF
731pointer at C<$center_x> and C<$center_y> (specified as factor of image
732width/height), generating a new image with width C<$new_width> and height
733C<$new_height>.
734 749
735#TODO# new width, height, maybe more operators? 750Anything that didn't fit any of the other categories, even after appliyng
751force and closing our eyes.
736 752
737Example: rotate the image by 90 degrees 753=over 4
738 754
739=cut 755=item once { ... }
740 756
741 sub rotate($$$$$$) { 757This function takes a code block as argument, that is, one or more
742 my $img = pop; 758statements enclosed by braces.
743 $img->rotate ( 759
744 $_[0], 760The trick is that this code block is only evaluated once - future calls
745 $_[1], 761will simply return the original image (yes, it should only be used with
746 $_[2] * $img->w, 762images).
747 $_[3] * $img->h, 763
748 $_[4] * (3.14159265 / 180), 764This can be extremely useful to avoid redoign the same slow operations
749 ) 765again and again- for example, if your background expression takes the root
766background, blurs it and then root-aligns it it would have to blur the
767root background on every window move or resize.
768
769Putting the blur into a C<once> block will make sure the blur is only done
770once:
771
772 rootlign once { blur 10, root }
773
774This leaves the question of how to force reevaluation of the block, in
775case the root background changes: Right now, all once blocks forget that
776they ahve been executed before each time the root background changes (if
777the expression is sensitive to that) or when C<once_again> is called.
778
779=item once_again
780
781Resets all C<once> block as if they had never been called, i.e. on the
782next call they will be reevaluated again.
783
784=cut
785
786 sub once(&) {
787 $_ONCE_CACHE{$_[0]+0} ||= $_[0]()
788 }
789
790 sub once_again() {
791 %_ONCE_CACHE = ();
750 } 792 }
751 793
752=back 794=back
753 795
754=cut 796=cut

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