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

Comparing rxvt-unicode/src/perl/background (file contents):
Revision 1.37 by root, Fri Jun 8 20:35:43 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
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
315	=back
316		305
317	=head2 TILING MODES	306	=head2 TILING MODES
318		307
319	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
320	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.
…		…
350	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
351	image over another image or the background colour while leaving all	340	image over another image or the background colour while leaving all
352	background pixels outside the image unchanged.	341	background pixels outside the image unchanged.
353		342
354	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
355	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
356	in alpha mode, else background colour).	345	in alpha mode, else background colour).
357		346
358	pad load "mybg.png"	347	pad load "mybg.png"
359		348
360	=item extend $img	349	=item extend $img
361		350
362	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
363	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
364	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
365	same values as the pixels near the edge.	354	same values as the pixels near the edge.
366		355
367	Example: just for curiosity, how does this pixel extension stuff work?	356	Example: just for curiosity, how does this pixel extension stuff work?
368		357
…		…
394	$img	383	$img
395	}	384	}
396		385
397	=back	386	=back
398		387
399	=head2 PIXEL OPERATORS	388	=head2 VARIABLE VALUES
400		389
401	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.
402		395
403	=over 4	396	=over 4
404		397
405	=item clone $img	398	=item TX
406		399
407	Returns an exact copy of the image.	400	=item TY
408		401
409	=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).
410		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} = $_[0];
		466	}
		467
411	sub clone($) {	468	sub counter($) {
412	$_[0]->clone	469	$new->{again}{time} = $_[0];
		470	$self->{counter} + 0
413	}	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
414		480
415	=item clip $img	481	=item clip $img
416		482
417	=item clip $width, $height, $img	483	=item clip $width, $height, $img
418		484
…		…
442	$img->sub_rect ($_[0], $_[1], $w, $h)	508	$img->sub_rect ($_[0], $_[1], $w, $h)
443	}	509	}
444		510
445	=item scale $img	511	=item scale $img
446		512
447	=item scale $size_percent, $img	513	=item scale $size_factor, $img
448		514
449	=item scale $width_percent, $height_percent, $img	515	=item scale $width_factor, $height_factor, $img
450		516
451	Scales the image by the given percentages in horizontal	517	Scales the image by the given factors in horizontal
452	(C<$width_percent>) and vertical (C<$height_percent>) direction.	518	(C<$width>) and vertical (C<$height>) direction.
453		519
454	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.
455		521
456	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
457	keeping aspect.	523	keeping aspect.
458		524
459	=item resize $width, $height, $img	525	=item resize $width, $height, $img
460		526
461	Resizes the image to exactly C<$width> times C<$height> pixels.	527	Resizes the image to exactly C<$width> times C<$height> pixels.
462		528
463	=cut	529	=item fit $img
464		530
465	#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, $img
		540
		541	Similar to C<fit>, but shrinks or grows until all of the area is covered
		542	by the image, so instead of potentially leaving borders, it will cut off
		543	image data that doesn't fit.
		544
		545	=cut
466		546
467	sub scale($;$;$) {	547	sub scale($;$;$) {
468	my $img = pop;	548	my $img = pop;
469		549
470	@_ == 2 ? $img->scale ($_[0] * $img->w * 0.01, $_[1] * $img->h * 0.01)	550	@_ == 2 ? $img->scale ($_[0] * $img->w, $_[1] * $img->h)
471	: @_ ? $img->scale ($_[0] * $img->w * 0.01, $_[0] * $img->h * 0.01)	551	: @_ ? $img->scale ($_[0] * $img->w, $_[0] * $img->h)
472	: $img->scale (TW, TH)	552	: $img->scale (TW, TH)
473	}	553	}
474		554
475	sub resize($$$) {	555	sub resize($$$) {
476	my $img = pop;	556	my $img = pop;
477	$img->scale ($_[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
478	}	572	}
479		573
480	=item move $dx, $dy, $img	574	=item move $dx, $dy, $img
481		575
482	Moves the image by C<$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
483	the vertical.	577	the vertical.
484		578
485	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.
486		580
487	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"
488		605
489	=item rootalign $img	606	=item rootalign $img
490		607
491	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
492	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
…		…
498	rootalign mirror load "mybg.png"	615	rootalign mirror load "mybg.png"
499		616
500	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
501	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.
502		619
503	rootalign root	620	rootalign root
504		621
505	=cut	622	=cut
506		623
507	sub move($$;$) {	624	sub move($$;$) {
508	my $img = pop->clone;	625	my $img = pop->clone;
509	$img->move ($_[0], $_[1]);	626	$img->move ($_[0], $_[1]);
510	$img	627	$img
511	}	628	}
512		629
		630	sub align($;$$) {
		631	my $img = pop;
		632
		633	move $_[0] * (TW - $img->w),
		634	$_[1] * (TH - $img->h),
		635	$img
		636	}
		637
		638	sub center($;$$) {
		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), $img
		644	}
		645
513	sub rootalign($) {	646	sub rootalign($) {
514	move -TX, -TY, $_[0]	647	move -TX, -TY, $_[0]
515	}	648	}
516		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($$$$) {
		663	my $img = pop;
		664	$img->rotate (
		665	$_[0] * $img->w,
		666	$_[1] * $img->h,
		667	$_[2] * (3.14159265 / 180),
		668	)
		669	}
		670
		671	=back
		672
		673	=head2 COLOUR MODIFICATIONS
		674
		675	The following operators change the pixels of the image.
		676
		677	=over 4
		678
517	=item contrast $factor, $img	679	=item contrast $factor, $img
518		680
519	=item contrast $r, $g, $b, $img	681	=item contrast $r, $g, $b, $img
520		682
521	=item contrast $r, $g, $b, $a, $img	683	=item contrast $r, $g, $b, $a, $img
522		684
523	Adjusts the I<contrast> of an image.	685	Adjusts the I<contrast> of an image.
524		686
		687	The first form applies a single C<$factor> to red, green and blue, the
		688	second form applies separate factors to each colour channel, and the last
		689	form includes the alpha channel.
		690
		691	Values from 0 to 1 lower the contrast, values higher than 1 increase the
		692	contrast.
		693
		694	Due to limitations in the underlying XRender extension, lowering contrast
		695	also reduces brightness, while increasing contrast currently also
		696	increases brightness.
		697
525	=item brightness $factor, $img	698	=item brightness $bias, $img
526		699
527	=item brightness $r, $g, $b, $img	700	=item brightness $r, $g, $b, $img
528		701
529	=item brightness $r, $g, $b, $a, $img	702	=item brightness $r, $g, $b, $a, $img
530		703
		704	Adjusts the brightness of an image.
		705
		706	The first form applies a single C<$bias> to red, green and blue, the
		707	second form applies separate biases to each colour channel, and the last
		708	form includes the alpha channel.
		709
		710	Values less than 0 reduce brightness, while values larger than 0 increase
		711	it. Useful range is from -1 to 1 - the former results in a black, the
		712	latter in a white picture.
		713
		714	Due to idiosyncrasies in the underlying XRender extension, biases less
		715	than zero can be I<very> slow.
		716
531	=cut	717	=cut
532		718
533	sub contrast($$;$$;$) {	719	sub contrast($$;$$;$) {
534	my $img = pop;	720	my $img = pop;
535	my ($r, $g, $b, $a) = @_;	721	my ($r, $g, $b, $a) = @_;
536		722
537	($g, $b) = ($r, $r) if @_ < 4;	723	($g, $b) = ($r, $r) if @_ < 3;
538	$a = 1 if @_ < 5;	724	$a = 1 if @_ < 4;
539		725
540	$img = $img->clone;	726	$img = $img->clone;
541	$img->contrast ($r, $g, $b, $a);	727	$img->contrast ($r, $g, $b, $a);
542	$img	728	$img
543	}	729	}
544		730
545	sub brightness($$;$$;$) {	731	sub brightness($$;$$;$) {
546	my $img = pop;	732	my $img = pop;
547	my ($r, $g, $b, $a) = @_;	733	my ($r, $g, $b, $a) = @_;
548		734
549	($g, $b) = ($r, $r) if @_ < 4;	735	($g, $b) = ($r, $r) if @_ < 3;
550	$a = 1 if @_ < 5;	736	$a = 1 if @_ < 4;
551		737
552	$img = $img->clone;	738	$img = $img->clone;
553	$img->brightness ($r, $g, $b, $a);	739	$img->brightness ($r, $g, $b, $a);
554	$img	740	$img
555	}	741	}
556		742
		743	=item blur $radius, $img
		744
		745	=item blur $radius_horz, $radius_vert, $img
		746
		747	Gaussian-blurs the image with (roughly) C<$radius> pixel radius. The radii
		748	can also be specified separately.
		749
		750	Blurring is often I<very> slow, at least compared or other
		751	operators. Larger blur radii are slower than smaller ones, too, so if you
		752	don't want to freeze your screen for long times, start experimenting with
		753	low values for radius (<5).
		754
		755	=cut
		756
557	sub blur($$;$) {	757	sub blur($$;$) {
558	my $img = pop;	758	my $img = pop;
559	$img->blur ($_[0], @_ >= 2 ? $_[1] : $_[0])	759	$img->blur ($_[0], @_ >= 2 ? $_[1] : $_[0])
560	}	760	}
561		761
562	sub rotate($$$$$$) {	762	=back
563	my $img = pop;	763
564	$img->rotate (	764	=head2 OTHER STUFF
565	$_[0],	765
566	$_[1],	766	Anything that didn't fit any of the other categories, even after appliyng
567	$_[2] * $img->w * .01,	767	force and closing our eyes.
568	$_[3] * $img->h * .01,	768
569	$_[4] * (3.14159265 / 180),	769	=over 4
		770
		771	=item once { ... }
		772
		773	This function takes a code block as argument, that is, one or more
		774	statements enclosed by braces.
		775
		776	The trick is that this code block is only evaluated once - future calls
		777	will simply return the original image (yes, it should only be used with
		778	images).
		779
		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]
570	)	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};
571	}	823	}
572		824
573	=back	825	=back
574		826
575	=cut	827	=cut
…		…
618		870
619	# evaluate user expression	871	# evaluate user expression
620		872
621	my $img = eval { $self->{expr}->() };	873	my $img = eval { $self->{expr}->() };
622	warn $@ if $@;#d#	874	warn $@ if $@;#d#
623	die if !UNIVERSAL::isa $img, "urxvt::img";	875	die "background-expr did not return an image.\n" if !UNIVERSAL::isa $img, "urxvt::img";
624		876
625	$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
626	if $img->repeat_mode != urxvt::RepeatNormal;	882	if $img->repeat_mode != urxvt::RepeatNormal;
627		883
628	# if the expression is sensitive to external events, prepare reevaluation then
629
630	my $repeat;
631
632	if (my $again = $state->{again}) {	884	if (my $again = $again->{time}) {
633	$repeat = 1;
634	my $self = $self;	885	my $self = $self;
635	$state->{timer} = $again == $old->{again}	886	$state->{timer} = $again == $old->{again}
636	? $old->{timer}	887	? $old->{timer}
637	: urxvt::timer->new->after ($again)->interval ($again)->cb (sub {	888	: urxvt::timer->new->after ($again)->interval ($again)->cb (sub {
638	++$self->{counter};	889	++$self->{counter};
639	$self->recalculate	890	$self->recalculate
640	});	891	});
641	}	892	}
642		893
643	if (delete $state->{position_sensitive}) {	894	if ($again->{position}) {
644	$repeat = 1;
645	$self->enable (position_change => sub { $_[0]->recalculate });	895	$self->enable (position_change => sub { $_[0]->recalculate });
646	} else {	896	} else {
647	$self->disable ("position_change");	897	$self->disable ("position_change");
648	}	898	}
649		899
650	if (delete $state->{size_sensitive}) {	900	if ($again->{size}) {
651	$repeat = 1;
652	$self->enable (size_change => sub { $_[0]->recalculate });	901	$self->enable (size_change => sub { $_[0]->recalculate });
653	} else {	902	} else {
654	$self->disable ("size_change");	903	$self->disable ("size_change");
655	}	904	}
656		905
657	if (delete $state->{rootpmap_sensitive}) {	906	if ($again->{rootpmap}) {
658	$repeat = 1;
659	$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	});
660	} else {	911	} else {
661	$self->disable ("rootpmap_change");	912	$self->disable ("rootpmap_change");
662	}	913	}
663		914
664	# clear stuff we no longer need	915	# clear stuff we no longer need
665		916
666	%$old = ();	917	%$old = ();
667		918
668	unless ($repeat) {	919	unless (%$again) {
669	delete $self->{state};	920	delete $self->{state};
670	delete $self->{expr};	921	delete $self->{expr};
671	}	922	}
672		923
673	# set background pixmap	924	# set background pixmap
…		…
678	}	929	}
679		930
680	sub on_start {	931	sub on_start {
681	my ($self) = @_;	932	my ($self) = @_;
682		933
683	my $expr = $self->x_resource ("background.expr")	934	my $expr = $self->x_resource ("%.expr")
684	or return;	935	or return;
685		936
		937	$self->has_render
		938	or die "background extension needs RENDER extension 0.10 or higher, ignoring background-expr.\n";
		939
686	$self->set_expr (parse_expr $expr);	940	$self->set_expr (parse_expr $expr);
687	$self->{border} = $self->x_resource_boolean ("background.border");	941	$self->{border} = $self->x_resource_boolean ("%.border");
		942
		943	$MIN_INTERVAL = $self->x_resource ("%.interval");
688		944
689	()	945	()
690	}	946	}
691		947

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Comparing rxvt-unicode/src/perl/background (file contents): Revision 1.37 by root, Fri Jun 8 20:35:43 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 1.37 by root, Fri Jun 8 20:35:43 2012 UTC vs.
Revision 1.55 by root, Thu Jun 14 16:48:57 2012 UTC