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

Comparing rxvt-unicode/src/perl/background (file contents):
Revision 1.39 by root, Fri Jun 8 22:19:03 2012 UTC vs.
Revision 1.60 by root, Fri Jun 15 13:21:59 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, $colour
246		278
247	Creates a new image and completely fills it with the given colour. The	279	Creates a new image and completely fills it with the given colour. The
248	image is set to tiling mode.	280	image is set to tiling mode.
249		281
250	If <$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, 0, $_[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		305
349	=back	306	=item merge $img ...
		307
		308	Takes any number of images and merges them together, creating a single
		309	image containing them all.
		310
		311	=cut
		312
		313	sub merge(@) {
		314	# rather annoyingly clumsy, but optimisation is for another time
		315
		316	my $x0 = +1e9;
		317	my $y0 = +1e9;
		318	my $x1 = -1e9;
		319	my $y1 = -1e9;
		320
		321	for (@_) {
		322	my ($x, $y, $w, $h) = $_->geometry;
		323
		324	$x0 = $x if $x0 > $x;
		325	$y0 = $y if $y0 > $y;
		326
		327	$x += $w;
		328	$y += $h;
		329
		330	$x1 = $x if $x1 < $x;
		331	$y1 = $y if $y1 < $y;
		332	}
		333
		334	my $base = $self->new_img (urxvt::PictStandardARGB32, $x0, $y0, $x1 - $x0, $y1 - $y0);
		335	$base->fill ([0, 0, 0, 0]);
		336
		337	$base->draw ($_)
		338	for @_;
		339
		340	$base
		341	}
350		342
351	=head2 TILING MODES	343	=head2 TILING MODES
352		344
353	The following operators modify the tiling mode of an image, that is, the	345	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.	346	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	376	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	377	image over another image or the background colour while leaving all
386	background pixels outside the image unchanged.	378	background pixels outside the image unchanged.
387		379
388	Example: load an image and display it in the upper left corner. The rest	380	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	381	of the space is left "empty" (transparent or whatever your compositor does
390	in alpha mode, else background colour).	382	in alpha mode, else background colour).
391		383
392	pad load "mybg.png"	384	pad load "mybg.png"
393		385
394	=item extend $img	386	=item extend $img
395		387
396	Extends the image over the whole plane, using the closest pixel in the	388	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	389	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	390	filtering operations and want the pixels outside the image to have the
399	same values as the pixels near the edge.	391	same values as the pixels near the edge.
400		392
401	Example: just for curiosity, how does this pixel extension stuff work?	393	Example: just for curiosity, how does this pixel extension stuff work?
402		394
…		…
428	$img	420	$img
429	}	421	}
430		422
431	=back	423	=back
432		424
433	=head2 PIXEL OPERATORS	425	=head2 VARIABLE VALUES
434		426
435	The following operators modify the image pixels in various ways.	427	The following functions provide variable data such as the terminal window
		428	dimensions. They are not (Perl-) variables, they just return stuff that
		429	varies. Most of them make your expression sensitive to some events, for
		430	example using C<TW> (terminal width) means your expression is evaluated
		431	again when the terminal is resized.
436		432
437	=over 4	433	=over 4
438		434
439	=item clone $img	435	=item TX
440		436
441	Returns an exact copy of the image.	437	=item TY
442		438
443	=cut	439	Return the X and Y coordinates of the terminal window (the terminal
		440	window is the full window by default, and the character area only when in
		441	border-respect mode).
444		442
		443	Using these functions make your expression sensitive to window moves.
		444
		445	These functions are mainly useful to align images to the root window.
		446
		447	Example: load an image and align it so it looks as if anchored to the
		448	background.
		449
		450	move -TX, -TY, load "mybg.png"
		451
		452	=item TW
		453
		454	Return the width (C<TW>) and height (C<TH>) of the terminal window (the
		455	terminal window is the full window by default, and the character area only
		456	when in border-respect mode).
		457
		458	Using these functions make your expression sensitive to window resizes.
		459
		460	These functions are mainly useful to scale images, or to clip images to
		461	the window size to conserve memory.
		462
		463	Example: take the screen background, clip it to the window size, blur it a
		464	bit, align it to the window position and use it as background.
		465
		466	clip move -TX, -TY, once { blur 5, root }
		467
		468	=cut
		469
		470	sub TX() { $new->{again}{position} = 1; $x }
		471	sub TY() { $new->{again}{position} = 1; $y }
		472	sub TW() { $new->{again}{size} = 1; $w }
		473	sub TH() { $new->{again}{size} = 1; $h }
		474
		475	=item now
		476
		477	Returns the current time as (fractional) seconds since the epoch.
		478
		479	Using this expression does I<not> make your expression sensitive to time,
		480	but the next two functions do.
		481
		482	=item again $seconds
		483
		484	When this function is used the expression will be reevaluated again in
		485	C<$seconds> seconds.
		486
		487	Example: load some image and rotate it according to the time of day (as if it were
		488	the hour pointer of a clock). Update this image every minute.
		489
		490	again 60; rotate 50, 50, (now % 86400) * -720 / 86400, scale load "myclock.png"
		491
		492	=item counter $seconds
		493
		494	Like C<again>, but also returns an increasing counter value, starting at
		495	0, which might be useful for some simple animation effects.
		496
		497	=cut
		498
		499	sub now() { urxvt::NOW }
		500
		501	sub again($) {
		502	$new->{again}{time} = $_[0];
		503	}
		504
445	sub clone($) {	505	sub counter($) {
446	$_[0]->clone	506	$new->{again}{time} = $_[0];
		507	$self->{counter} + 0
447	}	508	}
		509
		510	=back
		511
		512	=head2 SHAPE CHANGING OPERATORS
		513
		514	The following operators modify the shape, size or position of the image.
		515
		516	=over 4
448		517
449	=item clip $img	518	=item clip $img
450		519
451	=item clip $width, $height, $img	520	=item clip $width, $height, $img
452		521
…		…
476	$img->sub_rect ($_[0], $_[1], $w, $h)	545	$img->sub_rect ($_[0], $_[1], $w, $h)
477	}	546	}
478		547
479	=item scale $img	548	=item scale $img
480		549
481	=item scale $size_percent, $img	550	=item scale $size_factor, $img
482		551
483	=item scale $width_percent, $height_percent, $img	552	=item scale $width_factor, $height_factor, $img
484		553
485	Scales the image by the given percentages in horizontal	554	Scales the image by the given factors in horizontal
486	(C<$width_percent>) and vertical (C<$height_percent>) direction.	555	(C<$width>) and vertical (C<$height>) direction.
487		556
488	If only one percentage is give, it is used for both directions.	557	If only one factor is give, it is used for both directions.
489		558
490	If no percentages are given, scales the image to the window size without	559	If no factors are given, scales the image to the window size without
491	keeping aspect.	560	keeping aspect.
492		561
493	=item resize $width, $height, $img	562	=item resize $width, $height, $img
494		563
495	Resizes the image to exactly C<$width> times C<$height> pixels.	564	Resizes the image to exactly C<$width> times C<$height> pixels.
496		565
497	=cut	566	=item fit $img
498		567
499	#TODO: maximise, maximise_fill?	568	=item fit $width, $height, $img
		569
		570	Fits the image into the given C<$width> and C<$height> without changing
		571	aspect, or the terminal size. That means it will be shrunk or grown until
		572	the whole image fits into the given area, possibly leaving borders.
		573
		574	=item cover $img
		575
		576	=item cover $width, $height, $img
		577
		578	Similar to C<fit>, but shrinks or grows until all of the area is covered
		579	by the image, so instead of potentially leaving borders, it will cut off
		580	image data that doesn't fit.
		581
		582	=cut
500		583
501	sub scale($;$;$) {	584	sub scale($;$;$) {
502	my $img = pop;	585	my $img = pop;
503		586
504	@_ == 2 ? $img->scale ($_[0] * $img->w * 0.01, $_[1] * $img->h * 0.01)	587	@_ == 2 ? $img->scale ($_[0] * $img->w, $_[1] * $img->h)
505	: @_ ? $img->scale ($_[0] * $img->w * 0.01, $_[0] * $img->h * 0.01)	588	: @_ ? $img->scale ($_[0] * $img->w, $_[0] * $img->h)
506	: $img->scale (TW, TH)	589	: $img->scale (TW, TH)
507	}	590	}
508		591
509	sub resize($$$) {	592	sub resize($$$) {
510	my $img = pop;	593	my $img = pop;
511	$img->scale ($_[0], $_[1])	594	$img->scale ($_[0], $_[1])
		595	}
		596
		597	sub fit($;$$) {
		598	my $img = pop;
		599	my $w = ($_[0] \|\| TW) / $img->w;
		600	my $h = ($_[1] \|\| TH) / $img->h;
		601	scale +(min $w, $h), $img
		602	}
		603
		604	sub cover($;$$) {
		605	my $img = pop;
		606	my $w = ($_[0] \|\| TW) / $img->w;
		607	my $h = ($_[1] \|\| TH) / $img->h;
		608	scale +(max $w, $h), $img
512	}	609	}
513		610
514	=item move $dx, $dy, $img	611	=item move $dx, $dy, $img
515		612
516	Moves the image by C<$dx> pixels in the horizontal, and C<$dy> pixels in	613	Moves the image by C<$dx> pixels in the horizontal, and C<$dy> pixels in
517	the vertical.	614	the vertical.
518		615
519	Example: move the image right by 20 pixels and down by 30.	616	Example: move the image right by 20 pixels and down by 30.
520		617
521	move 20, 30, ...	618	move 20, 30, ...
		619
		620	=item align $xalign, $yalign, $img
		621
		622	Aligns the image according to a factor - C<0> means the image is moved to
		623	the left or top edge (for C<$xalign> or C<$yalign>), C<0.5> means it is
		624	exactly centered and C<1> means it touches the right or bottom edge.
		625
		626	Example: remove any visible border around an image, center it vertically but move
		627	it to the right hand side.
		628
		629	align 1, 0.5, pad $img
		630
		631	=item center $img
		632
		633	=item center $width, $height, $img
		634
		635	Centers the image, i.e. the center of the image is moved to the center of
		636	the terminal window (or the box specified by C<$width> and C<$height> if
		637	given).
		638
		639	Example: load an image and center it.
		640
		641	center pad load "mybg.png"
522		642
523	=item rootalign $img	643	=item rootalign $img
524		644
525	Moves the image so that it appears glued to the screen as opposed to the	645	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	646	window. This gives the illusion of a larger area behind the window. It is
…		…
532	rootalign mirror load "mybg.png"	652	rootalign mirror load "mybg.png"
533		653
534	Example: take the screen background and align it, giving the illusion of	654	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.	655	transparency as long as the window isn't in front of other windows.
536		656
537	rootalign root	657	rootalign root
538		658
539	=cut	659	=cut
540		660
541	sub move($$;$) {	661	sub move($$;$) {
542	my $img = pop->clone;	662	my $img = pop->clone;
543	$img->move ($_[0], $_[1]);	663	$img->move ($_[0], $_[1]);
544	$img	664	$img
545	}	665	}
546		666
		667	sub align($;$$) {
		668	my $img = pop;
		669
		670	move $_[0] * (TW - $img->w),
		671	$_[1] * (TH - $img->h),
		672	$img
		673	}
		674
		675	sub center($;$$) {
		676	my $img = pop;
		677	my $w = $_[0] \|\| TW;
		678	my $h = $_[1] \|\| TH;
		679
		680	move 0.5 * ($w - $img->w), 0.5 * ($h - $img->h), $img
		681	}
		682
547	sub rootalign($) {	683	sub rootalign($) {
548	move -TX, -TY, $_[0]	684	move -TX, -TY, $_[0]
549	}	685	}
550		686
		687	=item rotate $center_x, $center_y, $degrees
		688
		689	Rotates the image by C<$degrees> degrees, counter-clockwise, around the
		690	pointer at C<$center_x> and C<$center_y> (specified as factor of image
		691	width/height).
		692
		693	#TODO# new width, height, maybe more operators?
		694
		695	Example: rotate the image by 90 degrees
		696
		697	=cut
		698
		699	sub rotate($$$$) {
		700	my $img = pop;
		701	$img->rotate (
		702	$_[0] * ($img->w + $img->x),
		703	$_[1] * ($img->h + $img->y),
		704	$_[2] * (3.14159265 / 180),
		705	)
		706	}
		707
		708	=back
		709
		710	=head2 COLOUR MODIFICATIONS
		711
		712	The following operators change the pixels of the image.
		713
		714	=over 4
		715
551	=item contrast $factor, $img	716	=item contrast $factor, $img
552		717
553	=item contrast $r, $g, $b, $img	718	=item contrast $r, $g, $b, $img
554		719
555	=item contrast $r, $g, $b, $a, $img	720	=item contrast $r, $g, $b, $a, $img
556		721
557	Adjusts the I<contrast> of an image.	722	Adjusts the I<contrast> of an image.
558		723
559	#TODO#	724	The first form applies a single C<$factor> to red, green and blue, the
		725	second form applies separate factors to each colour channel, and the last
		726	form includes the alpha channel.
560		727
		728	Values from 0 to 1 lower the contrast, values higher than 1 increase the
		729	contrast.
		730
		731	Due to limitations in the underlying XRender extension, lowering contrast
		732	also reduces brightness, while increasing contrast currently also
		733	increases brightness.
		734
561	=item brightness $factor, $img	735	=item brightness $bias, $img
562		736
563	=item brightness $r, $g, $b, $img	737	=item brightness $r, $g, $b, $img
564		738
565	=item brightness $r, $g, $b, $a, $img	739	=item brightness $r, $g, $b, $a, $img
566		740
567	Adjusts the brightness of an image.	741	Adjusts the brightness of an image.
568		742
		743	The first form applies a single C<$bias> to red, green and blue, the
		744	second form applies separate biases to each colour channel, and the last
		745	form includes the alpha channel.
		746
		747	Values less than 0 reduce brightness, while values larger than 0 increase
		748	it. Useful range is from -1 to 1 - the former results in a black, the
		749	latter in a white picture.
		750
		751	Due to idiosyncrasies in the underlying XRender extension, biases less
		752	than zero can be I<very> slow.
		753
569	=cut	754	=cut
570		755
571	sub contrast($$;$$;$) {	756	sub contrast($$;$$;$) {
572	my $img = pop;	757	my $img = pop;
573	my ($r, $g, $b, $a) = @_;	758	my ($r, $g, $b, $a) = @_;
574		759
575	($g, $b) = ($r, $r) if @_ < 4;	760	($g, $b) = ($r, $r) if @_ < 3;
576	$a = 1 if @_ < 5;	761	$a = 1 if @_ < 4;
577		762
578	$img = $img->clone;	763	$img = $img->clone;
579	$img->contrast ($r, $g, $b, $a);	764	$img->contrast ($r, $g, $b, $a);
580	$img	765	$img
581	}	766	}
582		767
583	sub brightness($$;$$;$) {	768	sub brightness($$;$$;$) {
584	my $img = pop;	769	my $img = pop;
585	my ($r, $g, $b, $a) = @_;	770	my ($r, $g, $b, $a) = @_;
586		771
587	($g, $b) = ($r, $r) if @_ < 4;	772	($g, $b) = ($r, $r) if @_ < 3;
588	$a = 1 if @_ < 5;	773	$a = 1 if @_ < 4;
589		774
590	$img = $img->clone;	775	$img = $img->clone;
591	$img->brightness ($r, $g, $b, $a);	776	$img->brightness ($r, $g, $b, $a);
592	$img	777	$img
593	}	778	}
…		…
609	sub blur($$;$) {	794	sub blur($$;$) {
610	my $img = pop;	795	my $img = pop;
611	$img->blur ($_[0], @_ >= 2 ? $_[1] : $_[0])	796	$img->blur ($_[0], @_ >= 2 ? $_[1] : $_[0])
612	}	797	}
613		798
614	=item rotate $new_width, $new_height, $center_x, $center_y, $degrees	799	=back
615		800
616	Rotates the image by C<$degrees> degrees, counter-clockwise, around the	801	=head2 OTHER STUFF
617	pointer at C<$center_x> and C<$center_y> (specified as percentage of image
618	width/height), generating a new image with width C<$new_width> and height
619	C<$new_height>.
620		802
621	#TODO# new width, height, maybe more operators?	803	Anything that didn't fit any of the other categories, even after applying
		804	force and closing our eyes.
622		805
623	Example: rotate the image by 90 degrees	806	=over 4
624		807
625	=cut	808	=item once { ... }
626		809
627	sub rotate($$$$$$) {	810	This function takes a code block as argument, that is, one or more
628	my $img = pop;	811	statements enclosed by braces.
629	$img->rotate (	812
630	$_[0],	813	The trick is that this code block is only evaluated once - future calls
631	$_[1],	814	will simply return the original image (yes, it should only be used with
632	$_[2] * $img->w * .01,	815	images).
633	$_[3] * $img->h * .01,	816
634	$_[4] * (3.14159265 / 180),	817	This can be extremely useful to avoid redoign the same slow operations
		818	again and again- for example, if your background expression takes the root
		819	background, blurs it and then root-aligns it it would have to blur the
		820	root background on every window move or resize.
		821
		822	Putting the blur into a C<once> block will make sure the blur is only done
		823	once:
		824
		825	rootlign once { blur 10, root }
		826
		827	This leaves the question of how to force reevaluation of the block, in
		828	case the root background changes: Right now, all once blocks forget that
		829	they ahve been executed before each time the root background changes (if
		830	the expression is sensitive to that) or when C<once_again> is called.
		831
		832	=item once_again
		833
		834	Resets all C<once> block as if they had never been called, i.e. on the
		835	next call they will be reevaluated again.
		836
		837	=cut
		838
		839	sub once(&) {
		840	my $once = $self->{once_cache}{$_[0]+0} \|\|= do {
		841	local $new->{again};
		842	my @res = $_[0]();
		843	[$new->{again}, \@res]
635	)	844	};
		845
		846	$new->{again} = {
		847	%{ $new->{again} },
		848	%{ $once->[0] }
		849	};
		850
		851	# in scalar context we always return the first original result, which
		852	# is not quite how perl works.
		853	wantarray
		854	? @{ $once->[1] }
		855	: $once->[1][0]
		856	}
		857
		858	sub once_again() {
		859	delete $self->{once_cache};
636	}	860	}
637		861
638	=back	862	=back
639		863
640	=cut	864	=cut
…		…
683		907
684	# evaluate user expression	908	# evaluate user expression
685		909
686	my $img = eval { $self->{expr}->() };	910	my $img = eval { $self->{expr}->() };
687	warn $@ if $@;#d#	911	warn $@ if $@;#d#
688	die if !UNIVERSAL::isa $img, "urxvt::img";	912	die "background-expr did not return an image.\n" if !UNIVERSAL::isa $img, "urxvt::img";
689		913
690	$state->{size_sensitive} = 1	914	# if the expression is sensitive to external events, prepare reevaluation then
		915
		916	my $again = delete $state->{again};
		917
		918	$again->{size} = 1
691	if $img->repeat_mode != urxvt::RepeatNormal;	919	if $img->repeat_mode != urxvt::RepeatNormal;
692		920
693	# if the expression is sensitive to external events, prepare reevaluation then
694
695	my $repeat;
696
697	if (my $again = $state->{again}) {	921	if (my $again = $again->{time}) {
698	$repeat = 1;
699	my $self = $self;	922	my $self = $self;
700	$state->{timer} = $again == $old->{again}	923	$state->{timer} = $again == $old->{again}
701	? $old->{timer}	924	? $old->{timer}
702	: urxvt::timer->new->after ($again)->interval ($again)->cb (sub {	925	: urxvt::timer->new->after ($again)->interval ($again)->cb (sub {
703	++$self->{counter};	926	++$self->{counter};
704	$self->recalculate	927	$self->recalculate
705	});	928	});
706	}	929	}
707		930
708	if (delete $state->{position_sensitive}) {	931	if ($again->{position}) {
709	$repeat = 1;
710	$self->enable (position_change => sub { $_[0]->recalculate });	932	$self->enable (position_change => sub { $_[0]->recalculate });
711	} else {	933	} else {
712	$self->disable ("position_change");	934	$self->disable ("position_change");
713	}	935	}
714		936
715	if (delete $state->{size_sensitive}) {	937	if ($again->{size}) {
716	$repeat = 1;
717	$self->enable (size_change => sub { $_[0]->recalculate });	938	$self->enable (size_change => sub { $_[0]->recalculate });
718	} else {	939	} else {
719	$self->disable ("size_change");	940	$self->disable ("size_change");
720	}	941	}
721		942
722	if (delete $state->{rootpmap_sensitive}) {	943	if ($again->{rootpmap}) {
723	$repeat = 1;
724	$self->enable (rootpmap_change => sub { $_[0]->recalculate });	944	$self->enable (rootpmap_change => sub {
		945	delete $_[0]{once_cache}; # this will override once-block values from
		946	$_[0]->recalculate;
		947	});
725	} else {	948	} else {
726	$self->disable ("rootpmap_change");	949	$self->disable ("rootpmap_change");
727	}	950	}
728		951
729	# clear stuff we no longer need	952	# clear stuff we no longer need
730		953
731	%$old = ();	954	%$old = ();
732		955
733	unless ($repeat) {	956	unless (%$again) {
734	delete $self->{state};	957	delete $self->{state};
735	delete $self->{expr};	958	delete $self->{expr};
736	}	959	}
737		960
738	# set background pixmap	961	# set background pixmap
…		…
743	}	966	}
744		967
745	sub on_start {	968	sub on_start {
746	my ($self) = @_;	969	my ($self) = @_;
747		970
748	my $expr = $self->x_resource ("background.expr")	971	my $expr = $self->x_resource ("%.expr")
749	or return;	972	or return;
750		973
		974	$self->has_render
		975	or die "background extension needs RENDER extension 0.10 or higher, ignoring background-expr.\n";
		976
751	$self->set_expr (parse_expr $expr);	977	$self->set_expr (parse_expr $expr);
752	$self->{border} = $self->x_resource_boolean ("background.border");	978	$self->{border} = $self->x_resource_boolean ("%.border");
		979
		980	$MIN_INTERVAL = $self->x_resource ("%.interval");
753		981
754	()	982	()
755	}	983	}
756		984

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Comparing rxvt-unicode/src/perl/background (file contents): Revision 1.39 by root, Fri Jun 8 22:19:03 2012 UTC vs. Revision 1.60 by root, Fri Jun 15 13:21:59 2012 UTC

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Comparing rxvt-unicode/src/perl/background (file contents):
Revision 1.39 by root, Fri Jun 8 22:19:03 2012 UTC vs.
Revision 1.60 by root, Fri Jun 15 13:21:59 2012 UTC