[ViewVC] Diff of: cvs/rxvt-unicode/src/perl/background

Comparing rxvt-unicode/src/perl/background (file contents):
Revision 1.40 by root, Fri Jun 8 22:19:21 2012 UTC vs.
Revision 1.55 by root, Thu Jun 14 16:48:57 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		6
6	#TODO: once, rootalign	7	=head1 NAME
7		8
8	=head1 background - manage terminal background	9	background - manage terminal background
9		10
10	=head2 SYNOPSIS	11	=head1 SYNOPSIS
11		12
12	urxvt --background-expr 'background expression'	13	urxvt --background-expr 'background expression'
13	--background-border	14	--background-border
		15	--background-interval seconds
14		16
15	=head2 DESCRIPTION	17	=head1 DESCRIPTION
16		18
17	This extension manages the terminal background by creating a picture that	19	This extension manages the terminal background by creating a picture that
18	is behind the text, replacing the normal background colour.	20	is behind the text, replacing the normal background colour.
19		21
20	It does so by evaluating a Perl expression that I<calculates> the image on	22	It does so by evaluating a Perl expression that I<calculates> the image on
30		32
31	Or specified as a X resource:	33	Or specified as a X resource:
32		34
33	URxvt.background-expr: scale load "/path/to/mybg.png"	35	URxvt.background-expr: scale load "/path/to/mybg.png"
34		36
35	=head2 THEORY OF OPERATION	37	=head1 THEORY OF OPERATION
36		38
37	At startup, just before the window is mapped for the first time, the	39	At startup, just before the window is mapped for the first time, the
38	expression is evaluated and must yield an image. The image is then	40	expression is evaluated and must yield an image. The image is then
39	extended as necessary to cover the whole terminal window, and is set as a	41	extended as necessary to cover the whole terminal window, and is set as a
40	background pixmap.	42	background pixmap.
…		…
55		57
56	For example, an expression such as C<scale load "$HOME/mybg.png"> scales the	58	For example, an expression such as C<scale load "$HOME/mybg.png"> scales the
57	image to the window size, so it relies on the window size and will	59	image to the window size, so it relies on the window size and will
58	be reevaluated each time it is changed, but not when it moves for	60	be reevaluated each time it is changed, but not when it moves for
59	example. That ensures that the picture always fills the terminal, even	61	example. That ensures that the picture always fills the terminal, even
60	after it's size changes.	62	after its size changes.
61		63
62	=head3 EXPRESSIONS	64	=head2 EXPRESSIONS
63		65
64	Expressions are normal Perl expressions, in fact, they are Perl blocks -	66	Expressions are normal Perl expressions, in fact, they are Perl blocks -
65	which means you could use multiple lines and statements:	67	which means you could use multiple lines and statements:
66		68
67	again 3600;	69	again 3600;
…		…
69	return scale load "$HOME/weekday.png";	71	return scale load "$HOME/weekday.png";
70	} else {	72	} else {
71	return scale load "$HOME/sunday.png";	73	return scale load "$HOME/sunday.png";
72	}	74	}
73		75
74	This expression gets evaluated once per hour. It will set F<sunday.png> as	76	This expression is evaluated once per hour. It will set F<sunday.png> as
75	background on Sundays, and F<weekday.png> on all other days.	77	background on Sundays, and F<weekday.png> on all other days.
76		78
77	Fortunately, we expect that most expressions will be much simpler, with	79	Fortunately, we expect that most expressions will be much simpler, with
78	little Perl knowledge needed.	80	little Perl knowledge needed.
79		81
…		…
97	its result becomes the argument to the C<scale> function.	99	its result becomes the argument to the C<scale> function.
98		100
99	Many operators also allow some parameters preceding the input image	101	Many operators also allow some parameters preceding the input image
100	that modify its behaviour. For example, C<scale> without any additional	102	that modify its behaviour. For example, C<scale> without any additional
101	arguments scales the image to size of the terminal window. If you specify	103	arguments scales the image to size of the terminal window. If you specify
102	an additional argument, it uses it as a percentage:	104	an additional argument, it uses it as a scale factor (multiply by 100 to
		105	get a percentage):
103		106
104	scale 200, load "$HOME/mypic.png"	107	scale 2, load "$HOME/mypic.png"
105		108
106	This enlarges the image by a factor of 2 (200%). As you can see, C<scale>	109	This enlarges the image by a factor of 2 (200%). As you can see, C<scale>
107	has now two arguments, the C<200> and the C<load> expression, while	110	has now two arguments, the C<200> and the C<load> expression, while
108	C<load> only has one argument. Arguments are separated from each other by	111	C<load> only has one argument. Arguments are separated from each other by
109	commas.	112	commas.
110		113
111	Scale also accepts two arguments, which are then separate factors for both	114	Scale also accepts two arguments, which are then separate factors for both
112	horizontal and vertical dimensions. For example, this halves the image	115	horizontal and vertical dimensions. For example, this halves the image
113	width and doubles the image height:	116	width and doubles the image height:
114		117
115	scale 50, 200, load "$HOME/mypic.png"	118	scale 0.5, 2, load "$HOME/mypic.png"
116		119
117	Other effects than scalign are also readily available, for exmaple, you can	120	Other effects than scaling are also readily available, for example, you can
118	tile the image to fill the whole window, instead of resizing it:	121	tile the image to fill the whole window, instead of resizing it:
119		122
120	tile load "$HOME/mypic.png"	123	tile load "$HOME/mypic.png"
121		124
122	In fact, images returned by C<load> are in C<tile> mode by default, so the C<tile> operator	125	In fact, images returned by C<load> are in C<tile> mode by default, so the C<tile> operator
…		…
133	It first takes a snapshot of the screen background image, and then	136	It first takes a snapshot of the screen background image, and then
134	moves it to the upper left corner of the screen - the result is	137	moves it to the upper left corner of the screen - the result is
135	pseudo-transparency, as the image seems to be static while the window is	138	pseudo-transparency, as the image seems to be static while the window is
136	moved around.	139	moved around.
137		140
138	=head3 CYCLES AND CACHING	141	=head2 CYCLES AND CACHING
139		142
140	As has been mentioned before, the expression might be evaluated multiple	143	As has been mentioned before, the expression might be evaluated multiple
141	times. Each time the expression is reevaluated, a new cycle is said to	144	times. Each time the expression is reevaluated, a new cycle is said to
142	have begun. Many operators cache their results till the next cycle.	145	have begun. Many operators cache their results till the next cycle.
143		146
…		…
148	This only works for one cycle though, so as long as you load the same	151	This only works for one cycle though, so as long as you load the same
149	image every time, it will always be cached, but when you load a different	152	image every time, it will always be cached, but when you load a different
150	image, it will forget about the first one.	153	image, it will forget about the first one.
151		154
152	This allows you to either speed things up by keeping multiple images in	155	This allows you to either speed things up by keeping multiple images in
153	memory, or comserve memory by loading images more often.	156	memory, or conserve memory by loading images more often.
154		157
155	For example, you can keep two images in memory and use a random one like	158	For example, you can keep two images in memory and use a random one like
156	this:	159	this:
157		160
158	my $img1 = load "img1.png";	161	my $img1 = load "img1.png";
…		…
168		171
169	Here, a path is selected randomly, and load is only called for one image,	172	Here, a path is selected randomly, and load is only called for one image,
170	so keeps only one image in memory. If, on the next evaluation, luck	173	so keeps only one image in memory. If, on the next evaluation, luck
171	decides to use the other path, then it will have to load that image again.	174	decides to use the other path, then it will have to load that image again.
172		175
173	=head2 REFERENCE	176	=head1 REFERENCE
174		177
175	=head3 COMMAND LINE SWITCHES	178	=head2 COMMAND LINE SWITCHES
176		179
177	=over 4	180	=over 4
178		181
179	=item --background-expr perl-expression	182	=item --background-expr perl-expression
180		183
…		…
186	overwriting borders and any other areas, such as the scrollbar.	189	overwriting borders and any other areas, such as the scrollbar.
187		190
188	Specifying this flag changes the behaviour, so that the image only	191	Specifying this flag changes the behaviour, so that the image only
189	replaces the background of the character area.	192	replaces the background of the character area.
190		193
		194	=item --background-interval seconds
		195
		196	Since some operations in the underlying XRender extension can effectively
		197	freeze your X-server for prolonged time, this extension enforces a minimum
		198	time between updates, which is normally about 0.1 seconds.
		199
		200	If you want to do updates more often, you can decrease this safety
		201	interval with this switch.
		202
191	=back	203	=back
192		204
193	=cut	205	=cut
194		206
		207	our %_IMG_CACHE;
195	our $HOME;	208	our $HOME;
196	our ($self, $old, $new);	209	our ($self, $old, $new);
197	our ($x, $y, $w, $h);	210	our ($x, $y, $w, $h);
198		211
199	# enforce at least this interval between updates	212	# enforce at least this interval between updates
200	our $MIN_INTERVAL = 1/100;	213	our $MIN_INTERVAL = 6/59.951;
201		214
202	{	215	{
203	package urxvt::bgdsl; # background language	216	package urxvt::bgdsl; # background language
		217
		218	use List::Util qw(min max sum shuffle);
204		219
205	=head2 PROVIDERS/GENERATORS	220	=head2 PROVIDERS/GENERATORS
206		221
207	These functions provide an image, by loading it from disk, grabbing it	222	These functions provide an image, by loading it from disk, grabbing it
208	from the root screen or by simply generating it. They are used as starting	223	from the root screen or by simply generating it. They are used as starting
…		…
213	=item load $path	228	=item load $path
214		229
215	Loads the image at the given C<$path>. The image is set to plane tiling	230	Loads the image at the given C<$path>. The image is set to plane tiling
216	mode.	231	mode.
217		232
218	Loaded images will be cached for one cycle.	233	Loaded images will be cached for one cycle, and shared between temrinals
		234	running in the same process (e.g. in C<urxvtd>).
219		235
		236	=item load_uc $path
		237
		238	Load uncached - same as load, but does not cache the image. This function
		239	is most useufl if you want to optimise a background expression in some
		240	way.
		241
220	=cut	242	=cut
		243
		244	sub load_uc($) {
		245	my ($path) = @_;
		246
		247	$_IMG_CACHE{$path} \|\| do {
		248	my $img = $self->new_img_from_file ($path);
		249	Scalar::Util::weaken ($_IMG_CACHE{$path} = $img);
		250	$img
		251	}
		252	}
221		253
222	sub load($) {	254	sub load($) {
223	my ($path) = @_;	255	my ($path) = @_;
224		256
225	$new->{load}{$path} = $old->{load}{$path} \|\| $self->new_img_from_file ($path);	257	$new->{load}{$path} = $old->{load}{$path} \|\| load_uc $path;
226	}	258	}
227		259
228	=item root	260	=item root
229		261
230	Returns the root window pixmap, that is, hopefully, the background image	262	Returns the root window pixmap, that is, hopefully, the background image
…		…
234	reevaluated when the bg image changes.	266	reevaluated when the bg image changes.
235		267
236	=cut	268	=cut
237		269
238	sub root() {	270	sub root() {
239	$new->{rootpmap_sensitive} = 1;	271	$new->{again}{rootpmap} = 1;
240	die "root op not supported, exg, we need you";	272	$self->new_img_from_root
241	}	273	}
242		274
243	=item solid $colour	275	=item solid $colour
244		276
245	=item solid $width, $height, $colour	277	=item solid $width, $height, $colour
…		…
250	If C<$width> and C<$height> are omitted, it creates a 1x1 image, which is	282	If C<$width> and C<$height> are omitted, it creates a 1x1 image, which is
251	useful for solid backgrounds or for use in filtering effects.	283	useful for solid backgrounds or for use in filtering effects.
252		284
253	=cut	285	=cut
254		286
255	sub solid($$;$) {	287	sub solid($;$$) {
256	my $colour = pop;	288	my $colour = pop;
257		289
258	my $img = $self->new_img (urxvt::PictStandardARGB32, $_[0] \|\| 1, $_[1] \|\| 1);	290	my $img = $self->new_img (urxvt::PictStandardARGB32, $_[0] \|\| 1, $_[1] \|\| 1);
259	$img->fill ($colour);	291	$img->fill ($colour);
260	$img	292	$img
261	}	293	}
262		294
263	=back	295	=item clone $img
264		296
265	=head2 VARIABLES	297	Returns an exact copy of the image. This is useful if you want to have
		298	multiple copies of the same image to apply different effects to.
266		299
267	The following functions provide variable data such as the terminal
268	window dimensions. Most of them make your expression sensitive to some
269	events, for example using C<TW> (terminal width) means your expression is
270	evaluated again when the terminal is resized.
271
272	=over 4
273
274	=item TX
275
276	=item TY
277
278	Return the X and Y coordinates of the terminal window (the terminal
279	window is the full window by default, and the character area only when in
280	border-respect mode).
281
282	Using these functions make your expression sensitive to window moves.
283
284	These functions are mainly useful to align images to the root window.
285
286	Example: load an image and align it so it looks as if anchored to the
287	background.
288
289	move -TX, -TY, load "mybg.png"
290
291	=item TW
292
293	Return the width (C<TW>) and height (C<TH>) of the terminal window (the
294	terminal window is the full window by default, and the character area only
295	when in border-respect mode).
296
297	Using these functions make your expression sensitive to window resizes.
298
299	These functions are mainly useful to scale images, or to clip images to
300	the window size to conserve memory.
301
302	Example: take the screen background, clip it to the window size, blur it a
303	bit, align it to the window position and use it as background.
304
305	clip move -TX, -TY, blur 5, root
306
307	=cut	300	=cut
308		301
309	sub TX() { $new->{position_sensitive} = 1; $x }
310	sub TY() { $new->{position_sensitive} = 1; $y }
311	sub TW() { $new->{size_sensitive} = 1; $w }
312	sub TH() { $new->{size_sensitive} = 1; $h }
313
314	=item now
315
316	Returns the current time as (fractional) seconds since the epoch.
317
318	Using this expression does I<not> make your expression sensitive to time,
319	but the next two functions do.
320
321	=item again $seconds
322
323	When this function is used the expression will be reevaluated again in
324	C<$seconds> seconds.
325
326	Example: load some image and rotate it according to the time of day (as if it were
327	the hour pointer of a clock). Update this image every minute.
328
329	again 60; rotate TW, TH, 50, 50, (now % 86400) * -720 / 86400, scale load "myclock.png"
330
331	=item counter $seconds
332
333	Like C<again>, but also returns an increasing counter value, starting at
334	0, which might be useful for some simple animation effects.
335
336	=cut
337
338	sub now() { urxvt::NOW }
339
340	sub again($) {
341	$new->{again} = $_[0];
342	}
343
344	sub counter($) {	302	sub clone($) {
345	$new->{again} = $_[0];	303	$_[0]->clone
346	$self->{counter} + 0
347	}	304	}
348
349	=back
350		305
351	=head2 TILING MODES	306	=head2 TILING MODES
352		307
353	The following operators modify the tiling mode of an image, that is, the	308	The following operators modify the tiling mode of an image, that is, the
354	way that pixels outside the image area are painted when the image is used.	309	way that pixels outside the image area are painted when the image is used.
…		…
384	become transparent. This mode is most useful when you want to place an	339	become transparent. This mode is most useful when you want to place an
385	image over another image or the background colour while leaving all	340	image over another image or the background colour while leaving all
386	background pixels outside the image unchanged.	341	background pixels outside the image unchanged.
387		342
388	Example: load an image and display it in the upper left corner. The rest	343	Example: load an image and display it in the upper left corner. The rest
389	of the space is left "empty" (transparent or wahtever your compisotr does	344	of the space is left "empty" (transparent or whatever your compositor does
390	in alpha mode, else background colour).	345	in alpha mode, else background colour).
391		346
392	pad load "mybg.png"	347	pad load "mybg.png"
393		348
394	=item extend $img	349	=item extend $img
395		350
396	Extends the image over the whole plane, using the closest pixel in the	351	Extends the image over the whole plane, using the closest pixel in the
397	area outside the image. This mode is mostly useful when you more complex	352	area outside the image. This mode is mostly useful when you use more complex
398	filtering operations and want the pixels outside the image to have the	353	filtering operations and want the pixels outside the image to have the
399	same values as the pixels near the edge.	354	same values as the pixels near the edge.
400		355
401	Example: just for curiosity, how does this pixel extension stuff work?	356	Example: just for curiosity, how does this pixel extension stuff work?
402		357
…		…
428	$img	383	$img
429	}	384	}
430		385
431	=back	386	=back
432		387
433	=head2 PIXEL OPERATORS	388	=head2 VARIABLE VALUES
434		389
435	The following operators modify the image pixels in various ways.	390	The following functions provide variable data such as the terminal window
		391	dimensions. They are not (Perl-) variables, they just return stuff that
		392	varies. Most of them make your expression sensitive to some events, for
		393	example using C<TW> (terminal width) means your expression is evaluated
		394	again when the terminal is resized.
436		395
437	=over 4	396	=over 4
438		397
439	=item clone $img	398	=item TX
440		399
441	Returns an exact copy of the image.	400	=item TY
442		401
443	=cut	402	Return the X and Y coordinates of the terminal window (the terminal
		403	window is the full window by default, and the character area only when in
		404	border-respect mode).
444		405
		406	Using these functions make your expression sensitive to window moves.
		407
		408	These functions are mainly useful to align images to the root window.
		409
		410	Example: load an image and align it so it looks as if anchored to the
		411	background.
		412
		413	move -TX, -TY, load "mybg.png"
		414
		415	=item TW
		416
		417	Return the width (C<TW>) and height (C<TH>) of the terminal window (the
		418	terminal window is the full window by default, and the character area only
		419	when in border-respect mode).
		420
		421	Using these functions make your expression sensitive to window resizes.
		422
		423	These functions are mainly useful to scale images, or to clip images to
		424	the window size to conserve memory.
		425
		426	Example: take the screen background, clip it to the window size, blur it a
		427	bit, align it to the window position and use it as background.
		428
		429	clip move -TX, -TY, once { blur 5, root }
		430
		431	=cut
		432
		433	sub TX() { $new->{again}{position} = 1; $x }
		434	sub TY() { $new->{again}{position} = 1; $y }
		435	sub TW() { $new->{again}{size} = 1; $w }
		436	sub TH() { $new->{again}{size} = 1; $h }
		437
		438	=item now
		439
		440	Returns the current time as (fractional) seconds since the epoch.
		441
		442	Using this expression does I<not> make your expression sensitive to time,
		443	but the next two functions do.
		444
		445	=item again $seconds
		446
		447	When this function is used the expression will be reevaluated again in
		448	C<$seconds> seconds.
		449
		450	Example: load some image and rotate it according to the time of day (as if it were
		451	the hour pointer of a clock). Update this image every minute.
		452
		453	again 60; rotate 50, 50, (now % 86400) * -720 / 86400, scale load "myclock.png"
		454
		455	=item counter $seconds
		456
		457	Like C<again>, but also returns an increasing counter value, starting at
		458	0, which might be useful for some simple animation effects.
		459
		460	=cut
		461
		462	sub now() { urxvt::NOW }
		463
		464	sub again($) {
		465	$new->{again}{time} = $_[0];
		466	}
		467
445	sub clone($) {	468	sub counter($) {
446	$_[0]->clone	469	$new->{again}{time} = $_[0];
		470	$self->{counter} + 0
447	}	471	}
		472
		473	=back
		474
		475	=head2 SHAPE CHANGING OPERATORS
		476
		477	The following operators modify the shape, size or position of the image.
		478
		479	=over 4
448		480
449	=item clip $img	481	=item clip $img
450		482
451	=item clip $width, $height, $img	483	=item clip $width, $height, $img
452		484
…		…
476	$img->sub_rect ($_[0], $_[1], $w, $h)	508	$img->sub_rect ($_[0], $_[1], $w, $h)
477	}	509	}
478		510
479	=item scale $img	511	=item scale $img
480		512
481	=item scale $size_percent, $img	513	=item scale $size_factor, $img
482		514
483	=item scale $width_percent, $height_percent, $img	515	=item scale $width_factor, $height_factor, $img
484		516
485	Scales the image by the given percentages in horizontal	517	Scales the image by the given factors in horizontal
486	(C<$width_percent>) and vertical (C<$height_percent>) direction.	518	(C<$width>) and vertical (C<$height>) direction.
487		519
488	If only one percentage is give, it is used for both directions.	520	If only one factor is give, it is used for both directions.
489		521
490	If no percentages are given, scales the image to the window size without	522	If no factors are given, scales the image to the window size without
491	keeping aspect.	523	keeping aspect.
492		524
493	=item resize $width, $height, $img	525	=item resize $width, $height, $img
494		526
495	Resizes the image to exactly C<$width> times C<$height> pixels.	527	Resizes the image to exactly C<$width> times C<$height> pixels.
496		528
497	=cut	529	=item fit $img
498		530
499	#TODO: maximise, maximise_fill?	531	=item fit $width, $height, $img
		532
		533	Fits the image into the given C<$width> and C<$height> without changing
		534	aspect, or the terminal size. That means it will be shrunk or grown until
		535	the whole image fits into the given area, possibly leaving borders.
		536
		537	=item cover $img
		538
		539	=item cover $width, $height, $img
		540
		541	Similar to C<fit>, but shrinks or grows until all of the area is covered
		542	by the image, so instead of potentially leaving borders, it will cut off
		543	image data that doesn't fit.
		544
		545	=cut
500		546
501	sub scale($;$;$) {	547	sub scale($;$;$) {
502	my $img = pop;	548	my $img = pop;
503		549
504	@_ == 2 ? $img->scale ($_[0] * $img->w * 0.01, $_[1] * $img->h * 0.01)	550	@_ == 2 ? $img->scale ($_[0] * $img->w, $_[1] * $img->h)
505	: @_ ? $img->scale ($_[0] * $img->w * 0.01, $_[0] * $img->h * 0.01)	551	: @_ ? $img->scale ($_[0] * $img->w, $_[0] * $img->h)
506	: $img->scale (TW, TH)	552	: $img->scale (TW, TH)
507	}	553	}
508		554
509	sub resize($$$) {	555	sub resize($$$) {
510	my $img = pop;	556	my $img = pop;
511	$img->scale ($_[0], $_[1])	557	$img->scale ($_[0], $_[1])
		558	}
		559
		560	sub fit($;$$) {
		561	my $img = pop;
		562	my $w = ($_[0] \|\| TW) / $img->w;
		563	my $h = ($_[1] \|\| TH) / $img->h;
		564	scale +(min $w, $h), $img
		565	}
		566
		567	sub cover($;$$) {
		568	my $img = pop;
		569	my $w = ($_[0] \|\| TW) / $img->w;
		570	my $h = ($_[1] \|\| TH) / $img->h;
		571	scale +(max $w, $h), $img
512	}	572	}
513		573
514	=item move $dx, $dy, $img	574	=item move $dx, $dy, $img
515		575
516	Moves the image by C<$dx> pixels in the horizontal, and C<$dy> pixels in	576	Moves the image by C<$dx> pixels in the horizontal, and C<$dy> pixels in
517	the vertical.	577	the vertical.
518		578
519	Example: move the image right by 20 pixels and down by 30.	579	Example: move the image right by 20 pixels and down by 30.
520		580
521	move 20, 30, ...	581	move 20, 30, ...
		582
		583	=item align $xalign, $yalign, $img
		584
		585	Aligns the image according to a factor - C<0> means the image is moved to
		586	the left or top edge (for C<$xalign> or C<$yalign>), C<0.5> means it is
		587	exactly centered and C<1> means it touches the right or bottom edge.
		588
		589	Example: remove any visible border around an image, center it vertically but move
		590	it to the right hand side.
		591
		592	align 1, 0.5, pad $img
		593
		594	=item center $img
		595
		596	=item center $width, $height, $img
		597
		598	Centers the image, i.e. the center of the image is moved to the center of
		599	the terminal window (or the box specified by C<$width> and C<$height> if
		600	given).
		601
		602	Example: load an image and center it.
		603
		604	center pad load "mybg.png"
522		605
523	=item rootalign $img	606	=item rootalign $img
524		607
525	Moves the image so that it appears glued to the screen as opposed to the	608	Moves the image so that it appears glued to the screen as opposed to the
526	window. This gives the illusion of a larger area behind the window. It is	609	window. This gives the illusion of a larger area behind the window. It is
…		…
532	rootalign mirror load "mybg.png"	615	rootalign mirror load "mybg.png"
533		616
534	Example: take the screen background and align it, giving the illusion of	617	Example: take the screen background and align it, giving the illusion of
535	transparency as long as the window isn't in front of other windows.	618	transparency as long as the window isn't in front of other windows.
536		619
537	rootalign root	620	rootalign root
538		621
539	=cut	622	=cut
540		623
541	sub move($$;$) {	624	sub move($$;$) {
542	my $img = pop->clone;	625	my $img = pop->clone;
543	$img->move ($_[0], $_[1]);	626	$img->move ($_[0], $_[1]);
544	$img	627	$img
545	}	628	}
546		629
		630	sub align($;$$) {
		631	my $img = pop;
		632
		633	move $_[0] * (TW - $img->w),
		634	$_[1] * (TH - $img->h),
		635	$img
		636	}
		637
		638	sub center($;$$) {
		639	my $img = pop;
		640	my $w = $_[0] \|\| TW;
		641	my $h = $_[1] \|\| TH;
		642
		643	move 0.5 * ($w - $img->w), 0.5 * ($h - $img->h), $img
		644	}
		645
547	sub rootalign($) {	646	sub rootalign($) {
548	move -TX, -TY, $_[0]	647	move -TX, -TY, $_[0]
549	}	648	}
550		649
		650	=item rotate $center_x, $center_y, $degrees
		651
		652	Rotates the image by C<$degrees> degrees, counter-clockwise, around the
		653	pointer at C<$center_x> and C<$center_y> (specified as factor of image
		654	width/height).
		655
		656	#TODO# new width, height, maybe more operators?
		657
		658	Example: rotate the image by 90 degrees
		659
		660	=cut
		661
		662	sub rotate($$$$) {
		663	my $img = pop;
		664	$img->rotate (
		665	$_[0] * $img->w,
		666	$_[1] * $img->h,
		667	$_[2] * (3.14159265 / 180),
		668	)
		669	}
		670
		671	=back
		672
		673	=head2 COLOUR MODIFICATIONS
		674
		675	The following operators change the pixels of the image.
		676
		677	=over 4
		678
551	=item contrast $factor, $img	679	=item contrast $factor, $img
552		680
553	=item contrast $r, $g, $b, $img	681	=item contrast $r, $g, $b, $img
554		682
555	=item contrast $r, $g, $b, $a, $img	683	=item contrast $r, $g, $b, $a, $img
556		684
557	Adjusts the I<contrast> of an image.	685	Adjusts the I<contrast> of an image.
558		686
559	#TODO#	687	The first form applies a single C<$factor> to red, green and blue, the
		688	second form applies separate factors to each colour channel, and the last
		689	form includes the alpha channel.
560		690
		691	Values from 0 to 1 lower the contrast, values higher than 1 increase the
		692	contrast.
		693
		694	Due to limitations in the underlying XRender extension, lowering contrast
		695	also reduces brightness, while increasing contrast currently also
		696	increases brightness.
		697
561	=item brightness $factor, $img	698	=item brightness $bias, $img
562		699
563	=item brightness $r, $g, $b, $img	700	=item brightness $r, $g, $b, $img
564		701
565	=item brightness $r, $g, $b, $a, $img	702	=item brightness $r, $g, $b, $a, $img
566		703
567	Adjusts the brightness of an image.	704	Adjusts the brightness of an image.
568		705
		706	The first form applies a single C<$bias> to red, green and blue, the
		707	second form applies separate biases to each colour channel, and the last
		708	form includes the alpha channel.
		709
		710	Values less than 0 reduce brightness, while values larger than 0 increase
		711	it. Useful range is from -1 to 1 - the former results in a black, the
		712	latter in a white picture.
		713
		714	Due to idiosyncrasies in the underlying XRender extension, biases less
		715	than zero can be I<very> slow.
		716
569	=cut	717	=cut
570		718
571	sub contrast($$;$$;$) {	719	sub contrast($$;$$;$) {
572	my $img = pop;	720	my $img = pop;
573	my ($r, $g, $b, $a) = @_;	721	my ($r, $g, $b, $a) = @_;
574		722
575	($g, $b) = ($r, $r) if @_ < 4;	723	($g, $b) = ($r, $r) if @_ < 3;
576	$a = 1 if @_ < 5;	724	$a = 1 if @_ < 4;
577		725
578	$img = $img->clone;	726	$img = $img->clone;
579	$img->contrast ($r, $g, $b, $a);	727	$img->contrast ($r, $g, $b, $a);
580	$img	728	$img
581	}	729	}
582		730
583	sub brightness($$;$$;$) {	731	sub brightness($$;$$;$) {
584	my $img = pop;	732	my $img = pop;
585	my ($r, $g, $b, $a) = @_;	733	my ($r, $g, $b, $a) = @_;
586		734
587	($g, $b) = ($r, $r) if @_ < 4;	735	($g, $b) = ($r, $r) if @_ < 3;
588	$a = 1 if @_ < 5;	736	$a = 1 if @_ < 4;
589		737
590	$img = $img->clone;	738	$img = $img->clone;
591	$img->brightness ($r, $g, $b, $a);	739	$img->brightness ($r, $g, $b, $a);
592	$img	740	$img
593	}	741	}
…		…
609	sub blur($$;$) {	757	sub blur($$;$) {
610	my $img = pop;	758	my $img = pop;
611	$img->blur ($_[0], @_ >= 2 ? $_[1] : $_[0])	759	$img->blur ($_[0], @_ >= 2 ? $_[1] : $_[0])
612	}	760	}
613		761
614	=item rotate $new_width, $new_height, $center_x, $center_y, $degrees	762	=back
615		763
616	Rotates the image by C<$degrees> degrees, counter-clockwise, around the	764	=head2 OTHER STUFF
617	pointer at C<$center_x> and C<$center_y> (specified as percentage of image
618	width/height), generating a new image with width C<$new_width> and height
619	C<$new_height>.
620		765
621	#TODO# new width, height, maybe more operators?	766	Anything that didn't fit any of the other categories, even after appliyng
		767	force and closing our eyes.
622		768
623	Example: rotate the image by 90 degrees	769	=over 4
624		770
625	=cut	771	=item once { ... }
626		772
627	sub rotate($$$$$$) {	773	This function takes a code block as argument, that is, one or more
628	my $img = pop;	774	statements enclosed by braces.
629	$img->rotate (	775
630	$_[0],	776	The trick is that this code block is only evaluated once - future calls
631	$_[1],	777	will simply return the original image (yes, it should only be used with
632	$_[2] * $img->w * .01,	778	images).
633	$_[3] * $img->h * .01,	779
634	$_[4] * (3.14159265 / 180),	780	This can be extremely useful to avoid redoign the same slow operations
		781	again and again- for example, if your background expression takes the root
		782	background, blurs it and then root-aligns it it would have to blur the
		783	root background on every window move or resize.
		784
		785	Putting the blur into a C<once> block will make sure the blur is only done
		786	once:
		787
		788	rootlign once { blur 10, root }
		789
		790	This leaves the question of how to force reevaluation of the block, in
		791	case the root background changes: Right now, all once blocks forget that
		792	they ahve been executed before each time the root background changes (if
		793	the expression is sensitive to that) or when C<once_again> is called.
		794
		795	=item once_again
		796
		797	Resets all C<once> block as if they had never been called, i.e. on the
		798	next call they will be reevaluated again.
		799
		800	=cut
		801
		802	sub once(&) {
		803	my $once = $self->{once_cache}{$_[0]+0} \|\|= do {
		804	local $new->{again};
		805	my @res = $_[0]();
		806	[$new->{again}, \@res]
635	)	807	};
		808
		809	$new->{again} = {
		810	%{ $new->{again} },
		811	%{ $once->[0] }
		812	};
		813
		814	# in scalar context we always return the first original result, which
		815	# is not quite how perl works.
		816	wantarray
		817	? @{ $once->[1] }
		818	: $once->[1][0]
		819	}
		820
		821	sub once_again() {
		822	delete $self->{once_cache};
636	}	823	}
637		824
638	=back	825	=back
639		826
640	=cut	827	=cut
…		…
683		870
684	# evaluate user expression	871	# evaluate user expression
685		872
686	my $img = eval { $self->{expr}->() };	873	my $img = eval { $self->{expr}->() };
687	warn $@ if $@;#d#	874	warn $@ if $@;#d#
688	die if !UNIVERSAL::isa $img, "urxvt::img";	875	die "background-expr did not return an image.\n" if !UNIVERSAL::isa $img, "urxvt::img";
689		876
690	$state->{size_sensitive} = 1	877	# if the expression is sensitive to external events, prepare reevaluation then
		878
		879	my $again = delete $state->{again};
		880
		881	$again->{size} = 1
691	if $img->repeat_mode != urxvt::RepeatNormal;	882	if $img->repeat_mode != urxvt::RepeatNormal;
692		883
693	# if the expression is sensitive to external events, prepare reevaluation then
694
695	my $repeat;
696
697	if (my $again = $state->{again}) {	884	if (my $again = $again->{time}) {
698	$repeat = 1;
699	my $self = $self;	885	my $self = $self;
700	$state->{timer} = $again == $old->{again}	886	$state->{timer} = $again == $old->{again}
701	? $old->{timer}	887	? $old->{timer}
702	: urxvt::timer->new->after ($again)->interval ($again)->cb (sub {	888	: urxvt::timer->new->after ($again)->interval ($again)->cb (sub {
703	++$self->{counter};	889	++$self->{counter};
704	$self->recalculate	890	$self->recalculate
705	});	891	});
706	}	892	}
707		893
708	if (delete $state->{position_sensitive}) {	894	if ($again->{position}) {
709	$repeat = 1;
710	$self->enable (position_change => sub { $_[0]->recalculate });	895	$self->enable (position_change => sub { $_[0]->recalculate });
711	} else {	896	} else {
712	$self->disable ("position_change");	897	$self->disable ("position_change");
713	}	898	}
714		899
715	if (delete $state->{size_sensitive}) {	900	if ($again->{size}) {
716	$repeat = 1;
717	$self->enable (size_change => sub { $_[0]->recalculate });	901	$self->enable (size_change => sub { $_[0]->recalculate });
718	} else {	902	} else {
719	$self->disable ("size_change");	903	$self->disable ("size_change");
720	}	904	}
721		905
722	if (delete $state->{rootpmap_sensitive}) {	906	if ($again->{rootpmap}) {
723	$repeat = 1;
724	$self->enable (rootpmap_change => sub { $_[0]->recalculate });	907	$self->enable (rootpmap_change => sub {
		908	delete $_[0]{once_cache}; # this will override once-block values from
		909	$_[0]->recalculate;
		910	});
725	} else {	911	} else {
726	$self->disable ("rootpmap_change");	912	$self->disable ("rootpmap_change");
727	}	913	}
728		914
729	# clear stuff we no longer need	915	# clear stuff we no longer need
730		916
731	%$old = ();	917	%$old = ();
732		918
733	unless ($repeat) {	919	unless (%$again) {
734	delete $self->{state};	920	delete $self->{state};
735	delete $self->{expr};	921	delete $self->{expr};
736	}	922	}
737		923
738	# set background pixmap	924	# set background pixmap
…		…
743	}	929	}
744		930
745	sub on_start {	931	sub on_start {
746	my ($self) = @_;	932	my ($self) = @_;
747		933
748	my $expr = $self->x_resource ("background.expr")	934	my $expr = $self->x_resource ("%.expr")
749	or return;	935	or return;
750		936
		937	$self->has_render
		938	or die "background extension needs RENDER extension 0.10 or higher, ignoring background-expr.\n";
		939
751	$self->set_expr (parse_expr $expr);	940	$self->set_expr (parse_expr $expr);
752	$self->{border} = $self->x_resource_boolean ("background.border");	941	$self->{border} = $self->x_resource_boolean ("%.border");
		942
		943	$MIN_INTERVAL = $self->x_resource ("%.interval");
753		944
754	()	945	()
755	}	946	}
756		947

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Comparing rxvt-unicode/src/perl/background (file contents): Revision 1.40 by root, Fri Jun 8 22:19:21 2012 UTC vs. Revision 1.55 by root, Thu Jun 14 16:48:57 2012 UTC

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Comparing rxvt-unicode/src/perl/background (file contents):
Revision 1.40 by root, Fri Jun 8 22:19:21 2012 UTC vs.
Revision 1.55 by root, Thu Jun 14 16:48:57 2012 UTC