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

Comparing rxvt-unicode/src/perl/background (file contents):
Revision 1.38 by root, Fri Jun 8 21:48:07 2012 UTC vs.
Revision 1.56 by root, Thu Jun 14 17:06:57 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
80	Basically, you always start with a function that "generates" an image	82	Basically, you always start with a function that "generates" an image
…		…
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	TODO	120	Other effects than scaling are also readily available, for example, you can
		121	tile the image to fill the whole window, instead of resizing it:
118		122
		123	tile load "$HOME/mypic.png"
		124
		125	In fact, images returned by C<load> are in C<tile> mode by default, so the C<tile> operator
		126	is kind of superfluous.
		127
		128	Another common effect is to mirror the image, so that the same edges touch:
		129
		130	mirror load "$HOME/mypic.png"
		131
		132	This is also a typical background expression:
		133
		134	rootalign root
		135
		136	It first takes a snapshot of the screen background image, and then
		137	moves it to the upper left corner of the screen - the result is
		138	pseudo-transparency, as the image seems to be static while the window is
		139	moved around.
		140
119	=head3 CYCLES AND CACHING	141	=head2 CYCLES AND CACHING
120		142
121	TODO	143	As has been mentioned before, the expression might be evaluated multiple
122
123	Each time the expression is reevaluated, a new cycle is said to have begun. Many operators	144	times. Each time the expression is reevaluated, a new cycle is said to
124	cache their results till the next cycle. For example	145	have begun. Many operators cache their results till the next cycle.
125		146
		147	For example, the C<load> operator keeps a copy of the image. If it is
		148	asked to load the same image on the next cycle it will not load it again,
		149	but return the cached copy.
		150
		151	This only works for one cycle though, so as long as you load the same
		152	image every time, it will always be cached, but when you load a different
		153	image, it will forget about the first one.
		154
		155	This allows you to either speed things up by keeping multiple images in
		156	memory, or conserve memory by loading images more often.
		157
		158	For example, you can keep two images in memory and use a random one like
		159	this:
		160
		161	my $img1 = load "img1.png";
		162	my $img2 = load "img2.png";
		163	(0.5 > rand) ? $img1 : $img2
		164
		165	Since both images are "loaded" every time the expression is evaluated,
		166	they are always kept in memory. Contrast this version:
		167
		168	my $path1 = "img1.png";
		169	my $path2 = "img2.png";
		170	load ((0.5 > rand) ? $path1 : $path2)
		171
		172	Here, a path is selected randomly, and load is only called for one image,
		173	so keeps only one image in memory. If, on the next evaluation, luck
		174	decides to use the other path, then it will have to load that image again.
		175
126	=head2 REFERENCE	176	=head1 REFERENCE
127		177
128	=head3 COMMAND LINE SWITCHES	178	=head2 COMMAND LINE SWITCHES
129		179
130	=over 4	180	=over 4
131		181
132	=item --background-expr perl-expression	182	=item --background-expr perl-expression
133		183
…		…
139	overwriting borders and any other areas, such as the scrollbar.	189	overwriting borders and any other areas, such as the scrollbar.
140		190
141	Specifying this flag changes the behaviour, so that the image only	191	Specifying this flag changes the behaviour, so that the image only
142	replaces the background of the character area.	192	replaces the background of the character area.
143		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
144	=back	203	=back
145		204
146	=cut	205	=cut
147		206
148	our $EXPR;#d#	207	our %_IMG_CACHE;
149	#$EXPR = 'move W * 0.1, -H * 0.1, resize W * 0.5, H * 0.5, repeat_none load "opensource.png"';
150	$EXPR = 'move -TX, -TY, load "argb.png"';
151	#$EXPR = '
152	# rotate W, H, 50, 50, counter 1/59.95, repeat_mirror,
153	# clip X, Y, W, H, repeat_mirror,
154	# load "/root/pix/das_fette_schwein.jpg"
155	#';
156	#$EXPR = 'solid "red"';
157	#$EXPR = 'blur root, 10, 10'
158	#$EXPR = 'blur move (root, -x, -y), 5, 5'
159	#resize load "/root/pix/das_fette_schwein.jpg", w, h
160
161	our $HOME;	208	our $HOME;
162	our ($self, $old, $new);	209	our ($self, $old, $new);
163	our ($x, $y, $w, $h);	210	our ($x, $y, $w, $h);
164		211
165	# enforce at least this interval between updates	212	# enforce at least this interval between updates
166	our $MIN_INTERVAL = 1/100;	213	our $MIN_INTERVAL = 6/59.951;
167		214
168	{	215	{
169	package urxvt::bgdsl; # background language	216	package urxvt::bgdsl; # background language
		217
		218	use List::Util qw(min max sum shuffle);
170		219
171	=head2 PROVIDERS/GENERATORS	220	=head2 PROVIDERS/GENERATORS
172		221
173	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
174	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
…		…
179	=item load $path	228	=item load $path
180		229
181	Loads the image at the given C<$path>. The image is set to plane tiling	230	Loads the image at the given C<$path>. The image is set to plane tiling
182	mode.	231	mode.
183		232
184	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>).
185		235
		236	=item load_uc $path
		237
		238	Load uncached - same as load, but does not cache the image. This function
		239	is most useufl if you want to optimise a background expression in some
		240	way.
		241
186	=cut	242	=cut
		243
		244	sub load_uc($) {
		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	$img
		251	}
		252	}
187		253
188	sub load($) {	254	sub load($) {
189	my ($path) = @_;	255	my ($path) = @_;
190		256
191	$new->{load}{$path} = $old->{load}{$path} \|\| $self->new_img_from_file ($path);	257	$new->{load}{$path} = $old->{load}{$path} \|\| load_uc $path;
192	}	258	}
193		259
194	=item root	260	=item root
195		261
196	Returns the root window pixmap, that is, hopefully, the background image	262	Returns the root window pixmap, that is, hopefully, the background image
…		…
200	reevaluated when the bg image changes.	266	reevaluated when the bg image changes.
201		267
202	=cut	268	=cut
203		269
204	sub root() {	270	sub root() {
205	$new->{rootpmap_sensitive} = 1;	271	$new->{again}{rootpmap} = 1;
206	die "root op not supported, exg, we need you";	272	$self->new_img_from_root
207	}	273	}
208		274
209	=item solid $colour	275	=item solid $colour
210		276
211	=item solid $width, $height, $colour	277	=item solid $width, $height, $colour
212		278
213	Creates a new image and completely fills it with the given colour. The	279	Creates a new image and completely fills it with the given colour. The
214	image is set to tiling mode.	280	image is set to tiling mode.
215		281
216	If <$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
217	useful for solid backgrounds or for use in filtering effects.	283	useful for solid backgrounds or for use in filtering effects.
218		284
219	=cut	285	=cut
220		286
221	sub solid($$;$) {	287	sub solid($;$$) {
222	my $colour = pop;	288	my $colour = pop;
223		289
224	my $img = $self->new_img (urxvt::PictStandardARGB32, $_[0] \|\| 1, $_[1] \|\| 1);	290	my $img = $self->new_img (urxvt::PictStandardARGB32, $_[0] \|\| 1, $_[1] \|\| 1);
225	$img->fill ($colour);	291	$img->fill ($colour);
226	$img	292	$img
227	}	293	}
228		294
229	=back	295	=item clone $img
230		296
231	=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.
232		299
233	The following functions provide variable data such as the terminal
234	window dimensions. Most of them make your expression sensitive to some
235	events, for example using C<TW> (terminal width) means your expression is
236	evaluated again when the terminal is resized.
237
238	=over 4
239
240	=item TX
241
242	=item TY
243
244	Return the X and Y coordinates of the terminal window (the terminal
245	window is the full window by default, and the character area only when in
246	border-respect mode).
247
248	Using these functions make your expression sensitive to window moves.
249
250	These functions are mainly useful to align images to the root window.
251
252	Example: load an image and align it so it looks as if anchored to the
253	background.
254
255	move -TX, -TY, load "mybg.png"
256
257	=item TW
258
259	Return the width (C<TW>) and height (C<TH>) of the terminal window (the
260	terminal window is the full window by default, and the character area only
261	when in border-respect mode).
262
263	Using these functions make your expression sensitive to window resizes.
264
265	These functions are mainly useful to scale images, or to clip images to
266	the window size to conserve memory.
267
268	Example: take the screen background, clip it to the window size, blur it a
269	bit, align it to the window position and use it as background.
270
271	clip move -TX, -TY, blur 5, root
272
273	=cut	300	=cut
274		301
275	sub TX() { $new->{position_sensitive} = 1; $x }
276	sub TY() { $new->{position_sensitive} = 1; $y }
277	sub TW() { $new->{size_sensitive} = 1; $w }
278	sub TH() { $new->{size_sensitive} = 1; $h }
279
280	=item now
281
282	Returns the current time as (fractional) seconds since the epoch.
283
284	Using this expression does I<not> make your expression sensitive to time,
285	but the next two functions do.
286
287	=item again $seconds
288
289	When this function is used the expression will be reevaluated again in
290	C<$seconds> seconds.
291
292	Example: load some image and rotate it according to the time of day (as if it were
293	the hour pointer of a clock). Update this image every minute.
294
295	again 60; rotate TW, TH, 50, 50, (now % 86400) * -720 / 86400, scale load "myclock.png"
296
297	=item counter $seconds
298
299	Like C<again>, but also returns an increasing counter value, starting at
300	0, which might be useful for some simple animation effects.
301
302	=cut
303
304	sub now() { urxvt::NOW }
305
306	sub again($) {
307	$new->{again} = $_[0];
308	}
309
310	sub counter($) {	302	sub clone($) {
311	$new->{again} = $_[0];	303	$_[0]->clone
312	$self->{counter} + 0
313	}	304	}
314		305
315	=back	306	=item merge $img ...
		307
		308	Takes any number of images and merges them together, creating a single image containing them all.
		309
		310	=cut
		311
		312	sub merge(@) {
		313	#TODO
		314	}
316		315
317	=head2 TILING MODES	316	=head2 TILING MODES
318		317
319	The following operators modify the tiling mode of an image, that is, the	318	The following operators modify the tiling mode of an image, that is, the
320	way that pixels outside the image area are painted when the image is used.	319	way that pixels outside the image area are painted when the image is used.
…		…
350	become transparent. This mode is most useful when you want to place an	349	become transparent. This mode is most useful when you want to place an
351	image over another image or the background colour while leaving all	350	image over another image or the background colour while leaving all
352	background pixels outside the image unchanged.	351	background pixels outside the image unchanged.
353		352
354	Example: load an image and display it in the upper left corner. The rest	353	Example: load an image and display it in the upper left corner. The rest
355	of the space is left "empty" (transparent or wahtever your compisotr does	354	of the space is left "empty" (transparent or whatever your compositor does
356	in alpha mode, else background colour).	355	in alpha mode, else background colour).
357		356
358	pad load "mybg.png"	357	pad load "mybg.png"
359		358
360	=item extend $img	359	=item extend $img
361		360
362	Extends the image over the whole plane, using the closest pixel in the	361	Extends the image over the whole plane, using the closest pixel in the
363	area outside the image. This mode is mostly useful when you more complex	362	area outside the image. This mode is mostly useful when you use more complex
364	filtering operations and want the pixels outside the image to have the	363	filtering operations and want the pixels outside the image to have the
365	same values as the pixels near the edge.	364	same values as the pixels near the edge.
366		365
367	Example: just for curiosity, how does this pixel extension stuff work?	366	Example: just for curiosity, how does this pixel extension stuff work?
368		367
…		…
394	$img	393	$img
395	}	394	}
396		395
397	=back	396	=back
398		397
399	=head2 PIXEL OPERATORS	398	=head2 VARIABLE VALUES
400		399
401	The following operators modify the image pixels in various ways.	400	The following functions provide variable data such as the terminal window
		401	dimensions. They are not (Perl-) variables, they just return stuff that
		402	varies. Most of them make your expression sensitive to some events, for
		403	example using C<TW> (terminal width) means your expression is evaluated
		404	again when the terminal is resized.
402		405
403	=over 4	406	=over 4
404		407
405	=item clone $img	408	=item TX
406		409
407	Returns an exact copy of the image.	410	=item TY
408		411
409	=cut	412	Return the X and Y coordinates of the terminal window (the terminal
		413	window is the full window by default, and the character area only when in
		414	border-respect mode).
410		415
		416	Using these functions make your expression sensitive to window moves.
		417
		418	These functions are mainly useful to align images to the root window.
		419
		420	Example: load an image and align it so it looks as if anchored to the
		421	background.
		422
		423	move -TX, -TY, load "mybg.png"
		424
		425	=item TW
		426
		427	Return the width (C<TW>) and height (C<TH>) of the terminal window (the
		428	terminal window is the full window by default, and the character area only
		429	when in border-respect mode).
		430
		431	Using these functions make your expression sensitive to window resizes.
		432
		433	These functions are mainly useful to scale images, or to clip images to
		434	the window size to conserve memory.
		435
		436	Example: take the screen background, clip it to the window size, blur it a
		437	bit, align it to the window position and use it as background.
		438
		439	clip move -TX, -TY, once { blur 5, root }
		440
		441	=cut
		442
		443	sub TX() { $new->{again}{position} = 1; $x }
		444	sub TY() { $new->{again}{position} = 1; $y }
		445	sub TW() { $new->{again}{size} = 1; $w }
		446	sub TH() { $new->{again}{size} = 1; $h }
		447
		448	=item now
		449
		450	Returns the current time as (fractional) seconds since the epoch.
		451
		452	Using this expression does I<not> make your expression sensitive to time,
		453	but the next two functions do.
		454
		455	=item again $seconds
		456
		457	When this function is used the expression will be reevaluated again in
		458	C<$seconds> seconds.
		459
		460	Example: load some image and rotate it according to the time of day (as if it were
		461	the hour pointer of a clock). Update this image every minute.
		462
		463	again 60; rotate 50, 50, (now % 86400) * -720 / 86400, scale load "myclock.png"
		464
		465	=item counter $seconds
		466
		467	Like C<again>, but also returns an increasing counter value, starting at
		468	0, which might be useful for some simple animation effects.
		469
		470	=cut
		471
		472	sub now() { urxvt::NOW }
		473
		474	sub again($) {
		475	$new->{again}{time} = $_[0];
		476	}
		477
411	sub clone($) {	478	sub counter($) {
412	$_[0]->clone	479	$new->{again}{time} = $_[0];
		480	$self->{counter} + 0
413	}	481	}
		482
		483	=back
		484
		485	=head2 SHAPE CHANGING OPERATORS
		486
		487	The following operators modify the shape, size or position of the image.
		488
		489	=over 4
414		490
415	=item clip $img	491	=item clip $img
416		492
417	=item clip $width, $height, $img	493	=item clip $width, $height, $img
418		494
…		…
442	$img->sub_rect ($_[0], $_[1], $w, $h)	518	$img->sub_rect ($_[0], $_[1], $w, $h)
443	}	519	}
444		520
445	=item scale $img	521	=item scale $img
446		522
447	=item scale $size_percent, $img	523	=item scale $size_factor, $img
448		524
449	=item scale $width_percent, $height_percent, $img	525	=item scale $width_factor, $height_factor, $img
450		526
451	Scales the image by the given percentages in horizontal	527	Scales the image by the given factors in horizontal
452	(C<$width_percent>) and vertical (C<$height_percent>) direction.	528	(C<$width>) and vertical (C<$height>) direction.
453		529
454	If only one percentage is give, it is used for both directions.	530	If only one factor is give, it is used for both directions.
455		531
456	If no percentages are given, scales the image to the window size without	532	If no factors are given, scales the image to the window size without
457	keeping aspect.	533	keeping aspect.
458		534
459	=item resize $width, $height, $img	535	=item resize $width, $height, $img
460		536
461	Resizes the image to exactly C<$width> times C<$height> pixels.	537	Resizes the image to exactly C<$width> times C<$height> pixels.
462		538
463	=cut	539	=item fit $img
464		540
465	#TODO: maximise, maximise_fill?	541	=item fit $width, $height, $img
		542
		543	Fits the image into the given C<$width> and C<$height> without changing
		544	aspect, or the terminal size. That means it will be shrunk or grown until
		545	the whole image fits into the given area, possibly leaving borders.
		546
		547	=item cover $img
		548
		549	=item cover $width, $height, $img
		550
		551	Similar to C<fit>, but shrinks or grows until all of the area is covered
		552	by the image, so instead of potentially leaving borders, it will cut off
		553	image data that doesn't fit.
		554
		555	=cut
466		556
467	sub scale($;$;$) {	557	sub scale($;$;$) {
468	my $img = pop;	558	my $img = pop;
469		559
470	@_ == 2 ? $img->scale ($_[0] * $img->w * 0.01, $_[1] * $img->h * 0.01)	560	@_ == 2 ? $img->scale ($_[0] * $img->w, $_[1] * $img->h)
471	: @_ ? $img->scale ($_[0] * $img->w * 0.01, $_[0] * $img->h * 0.01)	561	: @_ ? $img->scale ($_[0] * $img->w, $_[0] * $img->h)
472	: $img->scale (TW, TH)	562	: $img->scale (TW, TH)
473	}	563	}
474		564
475	sub resize($$$) {	565	sub resize($$$) {
476	my $img = pop;	566	my $img = pop;
477	$img->scale ($_[0], $_[1])	567	$img->scale ($_[0], $_[1])
		568	}
		569
		570	sub fit($;$$) {
		571	my $img = pop;
		572	my $w = ($_[0] \|\| TW) / $img->w;
		573	my $h = ($_[1] \|\| TH) / $img->h;
		574	scale +(min $w, $h), $img
		575	}
		576
		577	sub cover($;$$) {
		578	my $img = pop;
		579	my $w = ($_[0] \|\| TW) / $img->w;
		580	my $h = ($_[1] \|\| TH) / $img->h;
		581	scale +(max $w, $h), $img
478	}	582	}
479		583
480	=item move $dx, $dy, $img	584	=item move $dx, $dy, $img
481		585
482	Moves the image by C<$dx> pixels in the horizontal, and C<$dy> pixels in	586	Moves the image by C<$dx> pixels in the horizontal, and C<$dy> pixels in
483	the vertical.	587	the vertical.
484		588
485	Example: move the image right by 20 pixels and down by 30.	589	Example: move the image right by 20 pixels and down by 30.
486		590
487	move 20, 30, ...	591	move 20, 30, ...
		592
		593	=item align $xalign, $yalign, $img
		594
		595	Aligns the image according to a factor - C<0> means the image is moved to
		596	the left or top edge (for C<$xalign> or C<$yalign>), C<0.5> means it is
		597	exactly centered and C<1> means it touches the right or bottom edge.
		598
		599	Example: remove any visible border around an image, center it vertically but move
		600	it to the right hand side.
		601
		602	align 1, 0.5, pad $img
		603
		604	=item center $img
		605
		606	=item center $width, $height, $img
		607
		608	Centers the image, i.e. the center of the image is moved to the center of
		609	the terminal window (or the box specified by C<$width> and C<$height> if
		610	given).
		611
		612	Example: load an image and center it.
		613
		614	center pad load "mybg.png"
488		615
489	=item rootalign $img	616	=item rootalign $img
490		617
491	Moves the image so that it appears glued to the screen as opposed to the	618	Moves the image so that it appears glued to the screen as opposed to the
492	window. This gives the illusion of a larger area behind the window. It is	619	window. This gives the illusion of a larger area behind the window. It is
…		…
498	rootalign mirror load "mybg.png"	625	rootalign mirror load "mybg.png"
499		626
500	Example: take the screen background and align it, giving the illusion of	627	Example: take the screen background and align it, giving the illusion of
501	transparency as long as the window isn't in front of other windows.	628	transparency as long as the window isn't in front of other windows.
502		629
503	rootalign root	630	rootalign root
504		631
505	=cut	632	=cut
506		633
507	sub move($$;$) {	634	sub move($$;$) {
508	my $img = pop->clone;	635	my $img = pop->clone;
509	$img->move ($_[0], $_[1]);	636	$img->move ($_[0], $_[1]);
510	$img	637	$img
511	}	638	}
512		639
		640	sub align($;$$) {
		641	my $img = pop;
		642
		643	move $_[0] * (TW - $img->w),
		644	$_[1] * (TH - $img->h),
		645	$img
		646	}
		647
		648	sub center($;$$) {
		649	my $img = pop;
		650	my $w = $_[0] \|\| TW;
		651	my $h = $_[1] \|\| TH;
		652
		653	move 0.5 * ($w - $img->w), 0.5 * ($h - $img->h), $img
		654	}
		655
513	sub rootalign($) {	656	sub rootalign($) {
514	move -TX, -TY, $_[0]	657	move -TX, -TY, $_[0]
515	}	658	}
516		659
		660	=item rotate $center_x, $center_y, $degrees
		661
		662	Rotates the image by C<$degrees> degrees, counter-clockwise, around the
		663	pointer at C<$center_x> and C<$center_y> (specified as factor of image
		664	width/height).
		665
		666	#TODO# new width, height, maybe more operators?
		667
		668	Example: rotate the image by 90 degrees
		669
		670	=cut
		671
		672	sub rotate($$$$) {
		673	my $img = pop;
		674	$img->rotate (
		675	$_[0] * $img->w,
		676	$_[1] * $img->h,
		677	$_[2] * (3.14159265 / 180),
		678	)
		679	}
		680
		681	=back
		682
		683	=head2 COLOUR MODIFICATIONS
		684
		685	The following operators change the pixels of the image.
		686
		687	=over 4
		688
517	=item contrast $factor, $img	689	=item contrast $factor, $img
518		690
519	=item contrast $r, $g, $b, $img	691	=item contrast $r, $g, $b, $img
520		692
521	=item contrast $r, $g, $b, $a, $img	693	=item contrast $r, $g, $b, $a, $img
522		694
523	Adjusts the I<contrast> of an image.	695	Adjusts the I<contrast> of an image.
524		696
525	#TODO#	697	The first form applies a single C<$factor> to red, green and blue, the
		698	second form applies separate factors to each colour channel, and the last
		699	form includes the alpha channel.
526		700
		701	Values from 0 to 1 lower the contrast, values higher than 1 increase the
		702	contrast.
		703
		704	Due to limitations in the underlying XRender extension, lowering contrast
		705	also reduces brightness, while increasing contrast currently also
		706	increases brightness.
		707
527	=item brightness $factor, $img	708	=item brightness $bias, $img
528		709
529	=item brightness $r, $g, $b, $img	710	=item brightness $r, $g, $b, $img
530		711
531	=item brightness $r, $g, $b, $a, $img	712	=item brightness $r, $g, $b, $a, $img
532		713
533	Adjusts the brightness of an image.	714	Adjusts the brightness of an image.
534		715
		716	The first form applies a single C<$bias> to red, green and blue, the
		717	second form applies separate biases to each colour channel, and the last
		718	form includes the alpha channel.
		719
		720	Values less than 0 reduce brightness, while values larger than 0 increase
		721	it. Useful range is from -1 to 1 - the former results in a black, the
		722	latter in a white picture.
		723
		724	Due to idiosyncrasies in the underlying XRender extension, biases less
		725	than zero can be I<very> slow.
		726
535	=cut	727	=cut
536		728
537	sub contrast($$;$$;$) {	729	sub contrast($$;$$;$) {
538	my $img = pop;	730	my $img = pop;
539	my ($r, $g, $b, $a) = @_;	731	my ($r, $g, $b, $a) = @_;
540		732
541	($g, $b) = ($r, $r) if @_ < 4;	733	($g, $b) = ($r, $r) if @_ < 3;
542	$a = 1 if @_ < 5;	734	$a = 1 if @_ < 4;
543		735
544	$img = $img->clone;	736	$img = $img->clone;
545	$img->contrast ($r, $g, $b, $a);	737	$img->contrast ($r, $g, $b, $a);
546	$img	738	$img
547	}	739	}
548		740
549	sub brightness($$;$$;$) {	741	sub brightness($$;$$;$) {
550	my $img = pop;	742	my $img = pop;
551	my ($r, $g, $b, $a) = @_;	743	my ($r, $g, $b, $a) = @_;
552		744
553	($g, $b) = ($r, $r) if @_ < 4;	745	($g, $b) = ($r, $r) if @_ < 3;
554	$a = 1 if @_ < 5;	746	$a = 1 if @_ < 4;
555		747
556	$img = $img->clone;	748	$img = $img->clone;
557	$img->brightness ($r, $g, $b, $a);	749	$img->brightness ($r, $g, $b, $a);
558	$img	750	$img
559	}	751	}
…		…
563	=item blur $radius_horz, $radius_vert, $img	755	=item blur $radius_horz, $radius_vert, $img
564		756
565	Gaussian-blurs the image with (roughly) C<$radius> pixel radius. The radii	757	Gaussian-blurs the image with (roughly) C<$radius> pixel radius. The radii
566	can also be specified separately.	758	can also be specified separately.
567		759
		760	Blurring is often I<very> slow, at least compared or other
		761	operators. Larger blur radii are slower than smaller ones, too, so if you
		762	don't want to freeze your screen for long times, start experimenting with
		763	low values for radius (<5).
		764
568	=cut	765	=cut
569		766
570	sub blur($$;$) {	767	sub blur($$;$) {
571	my $img = pop;	768	my $img = pop;
572	$img->blur ($_[0], @_ >= 2 ? $_[1] : $_[0])	769	$img->blur ($_[0], @_ >= 2 ? $_[1] : $_[0])
573	}	770	}
574		771
575	=item rotate $new_width, $new_height, $center_x, $center_y, $degrees	772	=back
576		773
577	Rotates the image by C<$degrees> degrees, counter-clockwise, around the	774	=head2 OTHER STUFF
578	pointer at C<$center_x> and C<$center_y> (specified as percentage of image
579	width/height), generating a new image with width C<$new_width> and height
580	C<$new_height>.
581		775
582	#TODO# new width, height, maybe more operators?	776	Anything that didn't fit any of the other categories, even after applying
		777	force and closing our eyes.
583		778
584	Example: rotate the image by 90 degrees	779	=over 4
585		780
586	=cut	781	=item once { ... }
587		782
588	sub rotate($$$$$$) {	783	This function takes a code block as argument, that is, one or more
589	my $img = pop;	784	statements enclosed by braces.
590	$img->rotate (	785
591	$_[0],	786	The trick is that this code block is only evaluated once - future calls
592	$_[1],	787	will simply return the original image (yes, it should only be used with
593	$_[2] * $img->w * .01,	788	images).
594	$_[3] * $img->h * .01,	789
595	$_[4] * (3.14159265 / 180),	790	This can be extremely useful to avoid redoign the same slow operations
		791	again and again- for example, if your background expression takes the root
		792	background, blurs it and then root-aligns it it would have to blur the
		793	root background on every window move or resize.
		794
		795	Putting the blur into a C<once> block will make sure the blur is only done
		796	once:
		797
		798	rootlign once { blur 10, root }
		799
		800	This leaves the question of how to force reevaluation of the block, in
		801	case the root background changes: Right now, all once blocks forget that
		802	they ahve been executed before each time the root background changes (if
		803	the expression is sensitive to that) or when C<once_again> is called.
		804
		805	=item once_again
		806
		807	Resets all C<once> block as if they had never been called, i.e. on the
		808	next call they will be reevaluated again.
		809
		810	=cut
		811
		812	sub once(&) {
		813	my $once = $self->{once_cache}{$_[0]+0} \|\|= do {
		814	local $new->{again};
		815	my @res = $_[0]();
		816	[$new->{again}, \@res]
596	)	817	};
		818
		819	$new->{again} = {
		820	%{ $new->{again} },
		821	%{ $once->[0] }
		822	};
		823
		824	# in scalar context we always return the first original result, which
		825	# is not quite how perl works.
		826	wantarray
		827	? @{ $once->[1] }
		828	: $once->[1][0]
		829	}
		830
		831	sub once_again() {
		832	delete $self->{once_cache};
597	}	833	}
598		834
599	=back	835	=back
600		836
601	=cut	837	=cut
…		…
644		880
645	# evaluate user expression	881	# evaluate user expression
646		882
647	my $img = eval { $self->{expr}->() };	883	my $img = eval { $self->{expr}->() };
648	warn $@ if $@;#d#	884	warn $@ if $@;#d#
649	die if !UNIVERSAL::isa $img, "urxvt::img";	885	die "background-expr did not return an image.\n" if !UNIVERSAL::isa $img, "urxvt::img";
650		886
651	$state->{size_sensitive} = 1	887	# if the expression is sensitive to external events, prepare reevaluation then
		888
		889	my $again = delete $state->{again};
		890
		891	$again->{size} = 1
652	if $img->repeat_mode != urxvt::RepeatNormal;	892	if $img->repeat_mode != urxvt::RepeatNormal;
653		893
654	# if the expression is sensitive to external events, prepare reevaluation then
655
656	my $repeat;
657
658	if (my $again = $state->{again}) {	894	if (my $again = $again->{time}) {
659	$repeat = 1;
660	my $self = $self;	895	my $self = $self;
661	$state->{timer} = $again == $old->{again}	896	$state->{timer} = $again == $old->{again}
662	? $old->{timer}	897	? $old->{timer}
663	: urxvt::timer->new->after ($again)->interval ($again)->cb (sub {	898	: urxvt::timer->new->after ($again)->interval ($again)->cb (sub {
664	++$self->{counter};	899	++$self->{counter};
665	$self->recalculate	900	$self->recalculate
666	});	901	});
667	}	902	}
668		903
669	if (delete $state->{position_sensitive}) {	904	if ($again->{position}) {
670	$repeat = 1;
671	$self->enable (position_change => sub { $_[0]->recalculate });	905	$self->enable (position_change => sub { $_[0]->recalculate });
672	} else {	906	} else {
673	$self->disable ("position_change");	907	$self->disable ("position_change");
674	}	908	}
675		909
676	if (delete $state->{size_sensitive}) {	910	if ($again->{size}) {
677	$repeat = 1;
678	$self->enable (size_change => sub { $_[0]->recalculate });	911	$self->enable (size_change => sub { $_[0]->recalculate });
679	} else {	912	} else {
680	$self->disable ("size_change");	913	$self->disable ("size_change");
681	}	914	}
682		915
683	if (delete $state->{rootpmap_sensitive}) {	916	if ($again->{rootpmap}) {
684	$repeat = 1;
685	$self->enable (rootpmap_change => sub { $_[0]->recalculate });	917	$self->enable (rootpmap_change => sub {
		918	delete $_[0]{once_cache}; # this will override once-block values from
		919	$_[0]->recalculate;
		920	});
686	} else {	921	} else {
687	$self->disable ("rootpmap_change");	922	$self->disable ("rootpmap_change");
688	}	923	}
689		924
690	# clear stuff we no longer need	925	# clear stuff we no longer need
691		926
692	%$old = ();	927	%$old = ();
693		928
694	unless ($repeat) {	929	unless (%$again) {
695	delete $self->{state};	930	delete $self->{state};
696	delete $self->{expr};	931	delete $self->{expr};
697	}	932	}
698		933
699	# set background pixmap	934	# set background pixmap
…		…
704	}	939	}
705		940
706	sub on_start {	941	sub on_start {
707	my ($self) = @_;	942	my ($self) = @_;
708		943
709	my $expr = $self->x_resource ("background.expr")	944	my $expr = $self->x_resource ("%.expr")
710	or return;	945	or return;
711		946
		947	$self->has_render
		948	or die "background extension needs RENDER extension 0.10 or higher, ignoring background-expr.\n";
		949
712	$self->set_expr (parse_expr $expr);	950	$self->set_expr (parse_expr $expr);
713	$self->{border} = $self->x_resource_boolean ("background.border");	951	$self->{border} = $self->x_resource_boolean ("%.border");
		952
		953	$MIN_INTERVAL = $self->x_resource ("%.interval");
714		954
715	()	955	()
716	}	956	}
717		957

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Comparing rxvt-unicode/src/perl/background (file contents): Revision 1.38 by root, Fri Jun 8 21:48:07 2012 UTC vs. Revision 1.56 by root, Thu Jun 14 17:06:57 2012 UTC

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Comparing rxvt-unicode/src/perl/background (file contents):
Revision 1.38 by root, Fri Jun 8 21:48:07 2012 UTC vs.
Revision 1.56 by root, Thu Jun 14 17:06:57 2012 UTC