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

Comparing rxvt-unicode/src/perl/background (file contents):
Revision 1.49 by root, Sun Jun 10 15:29:18 2012 UTC vs.
Revision 1.70 by root, Mon Jul 2 01:35:37 2012 UTC

…		…
2		2
3	#:META:X_RESOURCE:%.expr:string:background expression	3	#:META:X_RESOURCE:%.expr:string:background expression
4	#:META:X_RESOURCE:%.border:boolean:respect the terminal border	4	#:META:X_RESOURCE:%.border:boolean:respect the terminal border
5	#:META:X_RESOURCE:%.interval:seconds:minimum time between updates	5	#:META:X_RESOURCE:%.interval:seconds:minimum time between updates
6		6
7	#TODO: once, rootalign
8
9	=head1 NAME	7	=head1 NAME
10		8
11	background - manage terminal background	9	background - manage terminal background
12		10
13	=head1 SYNOPSIS	11	=head1 SYNOPSIS
…		…
28	to be as simple as possible.	26	to be as simple as possible.
29		27
30	For example, to load an image and scale it to the window size, you would	28	For example, to load an image and scale it to the window size, you would
31	use:	29	use:
32		30
33	urxvt --background-expr 'scale load "/path/to/mybg.png"'	31	urxvt --background-expr 'scale keep { load "/path/to/mybg.png" }'
34		32
35	Or specified as a X resource:	33	Or specified as a X resource:
36		34
37	URxvt.background-expr: scale load "/path/to/mybg.png"	35	URxvt.background-expr: scale keep { load "/path/to/mybg.png" }
38		36
39	=head1 THEORY OF OPERATION	37	=head1 THEORY OF OPERATION
40		38
41	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
42	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
…		…
55	If any of the parameters that the expression relies on changes (when the	53	If any of the parameters that the expression relies on changes (when the
56	window is moved or resized, its position or size changes; when the root	54	window is moved or resized, its position or size changes; when the root
57	pixmap is replaced by another one the root background changes; or when the	55	pixmap is replaced by another one the root background changes; or when the
58	timer elapses), then the expression will be evaluated again.	56	timer elapses), then the expression will be evaluated again.
59		57
60	For example, an expression such as C<scale load "$HOME/mybg.png"> scales the	58	For example, an expression such as C<scale keep { load "$HOME/mybg.png"
61	image to the window size, so it relies on the window size and will	59	}> scales the image to the window size, so it relies on the window size
62	be reevaluated each time it is changed, but not when it moves for	60	and will be reevaluated each time it is changed, but not when it moves for
63	example. That ensures that the picture always fills the terminal, even	61	example. That ensures that the picture always fills the terminal, even
64	after it's size changes.	62	after its size changes.
65		63
66	=head2 EXPRESSIONS	64	=head2 EXPRESSIONS
67		65
68	Expressions are normal Perl expressions, in fact, they are Perl blocks -	66	Expressions are normal Perl expressions, in fact, they are Perl blocks -
69	which means you could use multiple lines and statements:	67	which means you could use multiple lines and statements:
70		68
		69	scale keep {
71	again 3600;	70	again 3600;
72	if (localtime now)[6]) {	71	if (localtime now)[6]) {
73	return scale load "$HOME/weekday.png";	72	return load "$HOME/weekday.png";
74	} else {	73	} else {
75	return scale load "$HOME/sunday.png";	74	return load "$HOME/sunday.png";
		75	}
76	}	76	}
77		77
78	This expression gets evaluated once per hour. It will set F<sunday.png> as	78	This inner expression is evaluated once per hour (and whenever the
		79	temrinal window is resized). It sets F<sunday.png> as background on
79	background on Sundays, and F<weekday.png> on all other days.	80	Sundays, and F<weekday.png> on all other days.
80		81
81	Fortunately, we expect that most expressions will be much simpler, with	82	Fortunately, we expect that most expressions will be much simpler, with
82	little Perl knowledge needed.	83	little Perl knowledge needed.
83		84
84	Basically, you always start with a function that "generates" an image	85	Basically, you always start with a function that "generates" an image
…		…
117	horizontal and vertical dimensions. For example, this halves the image	118	horizontal and vertical dimensions. For example, this halves the image
118	width and doubles the image height:	119	width and doubles the image height:
119		120
120	scale 0.5, 2, load "$HOME/mypic.png"	121	scale 0.5, 2, load "$HOME/mypic.png"
121		122
122	Other effects than scalign are also readily available, for exmaple, you can	123	IF you try out these expressions, you might suffer from some sluggishness,
123	tile the image to fill the whole window, instead of resizing it:	124	because each time the terminal is resized, it loads the PNG image agin
		125	and scales it. Scaling is usually fast (and unavoidable), but loading the
		126	image can be quite time consuming. This is where C<keep> comes in handy:
124		127
		128	scale 0.5, 2, keep { load "$HOME/mypic.png" }
		129
		130	The C<keep> operator executes all the statements inside the braces only
		131	once, or when it thinks the outcome might change. In other cases it
		132	returns the last value computed by the brace block.
		133
		134	This means that the C<load> is only executed once, which makes it much
		135	faster, but also means that more memory is being used, because the loaded
		136	image must be kept in memory at all times. In this expression, the
		137	trade-off is likely worth it.
		138
		139	But back to effects: Other effects than scaling are also readily
		140	available, for example, you can tile the image to fill the whole window,
		141	instead of resizing it:
		142
125	tile load "$HOME/mypic.png"	143	tile keep { load "$HOME/mypic.png" }
126		144
127	In fact, images returned by C<load> are in C<tile> mode by default, so the C<tile> operator	145	In fact, images returned by C<load> are in C<tile> mode by default, so the
128	is kind of superfluous.	146	C<tile> operator is kind of superfluous.
129		147
130	Another common effect is to mirror the image, so that the same edges touch:	148	Another common effect is to mirror the image, so that the same edges
		149	touch:
131		150
132	mirror load "$HOME/mypic.png"	151	mirror keep { load "$HOME/mypic.png" }
133		152
134	This is also a typical background expression:	153	Another common background expression is:
135		154
136	rootalign root	155	rootalign root
137		156
138	It first takes a snapshot of the screen background image, and then	157	This one first takes a snapshot of the screen background image, and then
139	moves it to the upper left corner of the screen - the result is	158	moves it to the upper left corner of the screen (as opposed to the upper
140	pseudo-transparency, as the image seems to be static while the window is	159	left corner of the terminal window)- the result is pseudo-transparency:
141	moved around.	160	the image seems to be static while the window is moved around.
142		161
143	=head2 CYCLES AND CACHING	162	=head2 CACHING AND SENSITIVITY
144		163
145	As has been mentioned before, the expression might be evaluated multiple	164	Since some operations (such as C<load> and C<blur>) can take a long time,
146	times. Each time the expression is reevaluated, a new cycle is said to	165	caching results can be very important for a smooth operation. Caching can
147	have begun. Many operators cache their results till the next cycle.	166	also be useful to reduce memory usage, though, for example, when an image
		167	is cached by C<load>, it could be shared by multiple terminal windows
		168	running inside urxvtd.
148		169
149	For example, the C<load> operator keeps a copy of the image. If it is	170	=head3 C<keep { ... }> caching
150	asked to load the same image on the next cycle it will not load it again,
151	but return the cached copy.
152		171
153	This only works for one cycle though, so as long as you load the same	172	The most important way to cache expensive operations is to use C<keep {
154	image every time, it will always be cached, but when you load a different	173	... }>. The C<keep> operator takes a block of multiple statements enclosed
155	image, it will forget about the first one.	174	by C<{}> and keeps the return value in memory.
156		175
157	This allows you to either speed things up by keeping multiple images in	176	An expression can be "sensitive" to various external events, such as
158	memory, or comserve memory by loading images more often.	177	scaling or moving the window, root background changes and timers. Simply
		178	using an expression (such as C<scale> without parameters) that depends on
		179	certain changing values (called "variables"), or using those variables
		180	directly, will make an expression sensitive to these events - for example,
		181	using C<scale> or C<TW> will make the expression sensitive to the terminal
		182	size, and thus to resizing events.
159		183
160	For example, you can keep two images in memory and use a random one like	184	When such an event happens, C<keep> will automatically trigger a
161	this:	185	reevaluation of the whole expression with the new value of the expression.
162		186
163	my $img1 = load "img1.png";	187	C<keep> is most useful for expensive operations, such as C<blur>:
164	my $img2 = load "img2.png";
165	(0.5 > rand) ? $img1 : $img2
166		188
167	Since both images are "loaded" every time the expression is evaluated,	189	rootalign keep { blur 20, root }
168	they are always kept in memory. Contrast this version:
169		190
170	my $path1 = "img1.png";	191	This makes a blurred copy of the root background once, and on subsequent
171	my $path2 = "img2.png";	192	calls, just root-aligns it. Since C<blur> is usually quite slow and
172	load ((0.5 > rand) ? $path1 : $path2)	193	C<rootalign> is quite fast, this trades extra memory (for the cached
		194	blurred pixmap) with speed (blur only needs to be redone when root
		195	changes).
173		196
174	Here, a path is selected randomly, and load is only called for one image,	197	=head3 C<load> caching
175	so keeps only one image in memory. If, on the next evaluation, luck	198
176	decides to use the other path, then it will have to load that image again.	199	The C<load> operator itself does not keep images in memory, but as long as
		200	the image is still in memory, C<load> will use the in-memory image instead
		201	of loading it freshly from disk.
		202
		203	That means that this expression:
		204
		205	keep { load "$HOME/path..." }
		206
		207	Not only caches the image in memory, other terminal instances that try to
		208	C<load> it can reuse that in-memory copy.
177		209
178	=head1 REFERENCE	210	=head1 REFERENCE
179		211
180	=head2 COMMAND LINE SWITCHES	212	=head2 COMMAND LINE SWITCHES
181		213
…		…
193	Specifying this flag changes the behaviour, so that the image only	225	Specifying this flag changes the behaviour, so that the image only
194	replaces the background of the character area.	226	replaces the background of the character area.
195		227
196	=item --background-interval seconds	228	=item --background-interval seconds
197		229
198	Since some operations in the underlying XRender extension can effetively	230	Since some operations in the underlying XRender extension can effectively
199	freeze your X-server for prolonged time, this extension enforces a minimum	231	freeze your X-server for prolonged time, this extension enforces a minimum
200	time between updates, which is normally about 0.1 seconds.	232	time between updates, which is normally about 0.1 seconds.
201		233
202	If you want to do updates more often, you can decrease this safety	234	If you want to do updates more often, you can decrease this safety
203	interval with this switch.	235	interval with this switch.
204		236
205	=back	237	=back
206		238
207	=cut	239	=cut
208		240
209	our %_IMGCACHE;	241	our %_IMG_CACHE;
210	our $HOME;	242	our $HOME;
211	our ($self, $old, $new);	243	our ($self, $frame);
212	our ($x, $y, $w, $h);	244	our ($x, $y, $w, $h);
213		245
214	# enforce at least this interval between updates	246	# enforce at least this interval between updates
215	our $MIN_INTERVAL = 6/59.951;	247	our $MIN_INTERVAL = 6/59.951;
216		248
217	{	249	{
218	package urxvt::bgdsl; # background language	250	package urxvt::bgdsl; # background language
		251
		252	sub FR_PARENT() { 0 } # parent frame, if any - must be #0
		253	sub FR_CACHE () { 1 } # cached values
		254	sub FR_AGAIN () { 2 } # what this expr is sensitive to
		255	sub FR_STATE () { 3 } # watchers etc.
219		256
220	use List::Util qw(min max sum shuffle);	257	use List::Util qw(min max sum shuffle);
221		258
222	=head2 PROVIDERS/GENERATORS	259	=head2 PROVIDERS/GENERATORS
223		260
…		…
230	=item load $path	267	=item load $path
231		268
232	Loads the image at the given C<$path>. The image is set to plane tiling	269	Loads the image at the given C<$path>. The image is set to plane tiling
233	mode.	270	mode.
234		271
235	Loaded images will be cached for one cycle.	272	If the image is already in memory (e.g. because another terminal instance
		273	uses it), then the in-memory copy us returned instead.
		274
		275	=item load_uc $path
		276
		277	Load uncached - same as load, but does not cache the image, which means it
		278	is I<always> loaded from the filesystem again.
236		279
237	=cut	280	=cut
238		281
239	sub load($) {	282	sub load($) {
240	my ($path) = @_;	283	my ($path) = @_;
241		284
242	$new->{load}{$path} = $old->{load}{$path} \|\| $self->new_img_from_file ($path);	285	$_IMG_CACHE{$path} \|\| do {
		286	my $img = $self->new_img_from_file ($path);
		287	Scalar::Util::weaken ($_IMG_CACHE{$path} = $img);
		288	$img
		289	}
243	}	290	}
244		291
245	=item root	292	=item root
246		293
247	Returns the root window pixmap, that is, hopefully, the background image	294	Returns the root window pixmap, that is, hopefully, the background image
248	of your screen. The image is set to extend mode.	295	of your screen.
249		296
250	This function makes your expression root sensitive, that means it will be	297	This function makes your expression root sensitive, that means it will be
251	reevaluated when the bg image changes.	298	reevaluated when the bg image changes.
252		299
253	=cut	300	=cut
254		301
255	sub root() {	302	sub root() {
256	$new->{rootpmap_sensitive} = 1;	303	$frame->[FR_AGAIN]{rootpmap} = 1;
257	die "root op not supported, exg, we need you";	304	$self->new_img_from_root
258	}	305	}
259		306
260	=item solid $colour	307	=item solid $colour
261		308
262	=item solid $width, $height, $colour	309	=item solid $width, $height, $colour
…		…
270	=cut	317	=cut
271		318
272	sub solid($;$$) {	319	sub solid($;$$) {
273	my $colour = pop;	320	my $colour = pop;
274		321
275	my $img = $self->new_img (urxvt::PictStandardARGB32, $_[0] \|\| 1, $_[1] \|\| 1);	322	my $img = $self->new_img (urxvt::PictStandardARGB32, 0, 0, $_[0] \|\| 1, $_[1] \|\| 1);
276	$img->fill ($colour);	323	$img->fill ($colour);
277	$img	324	$img
278	}	325	}
279		326
280	=item clone $img	327	=item clone $img
…		…
286		333
287	sub clone($) {	334	sub clone($) {
288	$_[0]->clone	335	$_[0]->clone
289	}	336	}
290		337
291	=back	338	=item merge $img ...
		339
		340	Takes any number of images and merges them together, creating a single
		341	image containing them all. The tiling mode of the first image is used as
		342	the tiling mode of the resulting image.
		343
		344	This function is called automatically when an expression returns multiple
		345	images.
		346
		347	=cut
		348
		349	sub merge(@) {
		350	return $_[0] unless $#_;
		351
		352	# rather annoyingly clumsy, but optimisation is for another time
		353
		354	my $x0 = +1e9;
		355	my $y0 = +1e9;
		356	my $x1 = -1e9;
		357	my $y1 = -1e9;
		358
		359	for (@_) {
		360	my ($x, $y, $w, $h) = $_->geometry;
		361
		362	$x0 = $x if $x0 > $x;
		363	$y0 = $y if $y0 > $y;
		364
		365	$x += $w;
		366	$y += $h;
		367
		368	$x1 = $x if $x1 < $x;
		369	$y1 = $y if $y1 < $y;
		370	}
		371
		372	my $base = $self->new_img (urxvt::PictStandardARGB32, $x0, $y0, $x1 - $x0, $y1 - $y0);
		373	$base->repeat_mode ($_[0]->repeat_mode);
		374	$base->fill ([0, 0, 0, 0]);
		375
		376	$base->draw ($_)
		377	for @_;
		378
		379	$base
		380	}
292		381
293	=head2 TILING MODES	382	=head2 TILING MODES
294		383
295	The following operators modify the tiling mode of an image, that is, the	384	The following operators modify the tiling mode of an image, that is, the
296	way that pixels outside the image area are painted when the image is used.	385	way that pixels outside the image area are painted when the image is used.
…		…
326	become transparent. This mode is most useful when you want to place an	415	become transparent. This mode is most useful when you want to place an
327	image over another image or the background colour while leaving all	416	image over another image or the background colour while leaving all
328	background pixels outside the image unchanged.	417	background pixels outside the image unchanged.
329		418
330	Example: load an image and display it in the upper left corner. The rest	419	Example: load an image and display it in the upper left corner. The rest
331	of the space is left "empty" (transparent or wahtever your compisotr does	420	of the space is left "empty" (transparent or whatever your compositor does
332	in alpha mode, else background colour).	421	in alpha mode, else background colour).
333		422
334	pad load "mybg.png"	423	pad load "mybg.png"
335		424
336	=item extend $img	425	=item extend $img
337		426
338	Extends the image over the whole plane, using the closest pixel in the	427	Extends the image over the whole plane, using the closest pixel in the
339	area outside the image. This mode is mostly useful when you more complex	428	area outside the image. This mode is mostly useful when you use more complex
340	filtering operations and want the pixels outside the image to have the	429	filtering operations and want the pixels outside the image to have the
341	same values as the pixels near the edge.	430	same values as the pixels near the edge.
342		431
343	Example: just for curiosity, how does this pixel extension stuff work?	432	Example: just for curiosity, how does this pixel extension stuff work?
344		433
…		…
393	Using these functions make your expression sensitive to window moves.	482	Using these functions make your expression sensitive to window moves.
394		483
395	These functions are mainly useful to align images to the root window.	484	These functions are mainly useful to align images to the root window.
396		485
397	Example: load an image and align it so it looks as if anchored to the	486	Example: load an image and align it so it looks as if anchored to the
398	background.	487	background (that's exactly what C<rootalign> does btw.):
399		488
400	move -TX, -TY, load "mybg.png"	489	move -TX, -TY, keep { load "mybg.png" }
401		490
402	=item TW	491	=item TW
403		492
404	Return the width (C<TW>) and height (C<TH>) of the terminal window (the	493	Return the width (C<TW>) and height (C<TH>) of the terminal window (the
405	terminal window is the full window by default, and the character area only	494	terminal window is the full window by default, and the character area only
…		…
411	the window size to conserve memory.	500	the window size to conserve memory.
412		501
413	Example: take the screen background, clip it to the window size, blur it a	502	Example: take the screen background, clip it to the window size, blur it a
414	bit, align it to the window position and use it as background.	503	bit, align it to the window position and use it as background.
415		504
416	clip move -TX, -TY, blur 5, root	505	clip move -TX, -TY, keep { blur 5, root }
417		506
418	=cut	507	=cut
419		508
420	sub TX() { $new->{position_sensitive} = 1; $x }	509	sub TX() { $frame->[FR_AGAIN]{position} = 1; $x }
421	sub TY() { $new->{position_sensitive} = 1; $y }	510	sub TY() { $frame->[FR_AGAIN]{position} = 1; $y }
422	sub TW() { $new->{size_sensitive} = 1; $w }	511	sub TW() { $frame->[FR_AGAIN]{size} = 1; $w }
423	sub TH() { $new->{size_sensitive} = 1; $h }	512	sub TH() { $frame->[FR_AGAIN]{size} = 1; $h }
424		513
425	=item now	514	=item now
426		515
427	Returns the current time as (fractional) seconds since the epoch.	516	Returns the current time as (fractional) seconds since the epoch.
428		517
…		…
435	C<$seconds> seconds.	524	C<$seconds> seconds.
436		525
437	Example: load some image and rotate it according to the time of day (as if it were	526	Example: load some image and rotate it according to the time of day (as if it were
438	the hour pointer of a clock). Update this image every minute.	527	the hour pointer of a clock). Update this image every minute.
439		528
		529	again 60;
440	again 60; rotate TW, TH, 50, 50, (now % 86400) * -720 / 86400, scale load "myclock.png"	530	rotate 50, 50, (now % 86400) * -72 / 8640, scale keep { load "myclock.png" }
441		531
442	=item counter $seconds	532	=item counter $seconds
443		533
444	Like C<again>, but also returns an increasing counter value, starting at	534	Like C<again>, but also returns an increasing counter value, starting at
445	0, which might be useful for some simple animation effects.	535	0, which might be useful for some simple animation effects.
…		…
447	=cut	537	=cut
448		538
449	sub now() { urxvt::NOW }	539	sub now() { urxvt::NOW }
450		540
451	sub again($) {	541	sub again($) {
452	$new->{again} = $_[0];	542	$frame->[FR_AGAIN]{time} = $_[0];
453	}	543	}
454		544
455	sub counter($) {	545	sub counter($) {
456	$new->{again} = $_[0];	546	$frame->[FR_AGAIN]{time} = $_[0];
457	$self->{counter} + 0	547	$frame->[FR_STATE]{counter} + 0
458	}	548	}
459		549
460	=back	550	=back
461		551
462	=head2 SHAPE CHANGING OPERATORS	552	=head2 SHAPE CHANGING OPERATORS
…		…
482	assumed.	572	assumed.
483		573
484	Example: load an image, blur it, and clip it to the window size to save	574	Example: load an image, blur it, and clip it to the window size to save
485	memory.	575	memory.
486		576
487	clip blur 10, load "mybg.png"	577	clip keep { blur 10, load "mybg.png" }
488		578
489	=cut	579	=cut
490		580
491	sub clip($;$$;$$) {	581	sub clip($;$$;$$) {
492	my $img = pop;	582	my $img = pop;
…		…
586	the terminal window (or the box specified by C<$width> and C<$height> if	676	the terminal window (or the box specified by C<$width> and C<$height> if
587	given).	677	given).
588		678
589	Example: load an image and center it.	679	Example: load an image and center it.
590		680
591	center pad load "mybg.png"	681	center keep { pad load "mybg.png" }
592		682
593	=item rootalign $img	683	=item rootalign $img
594		684
595	Moves the image so that it appears glued to the screen as opposed to the	685	Moves the image so that it appears glued to the screen as opposed to the
596	window. This gives the illusion of a larger area behind the window. It is	686	window. This gives the illusion of a larger area behind the window. It is
597	exactly equivalent to C<move -TX, -TY>, that is, it moves the image to the	687	exactly equivalent to C<move -TX, -TY>, that is, it moves the image to the
598	top left of the screen.	688	top left of the screen.
599		689
600	Example: load a background image, put it in mirror mode and root align it.	690	Example: load a background image, put it in mirror mode and root align it.
601		691
602	rootalign mirror load "mybg.png"	692	rootalign keep { mirror load "mybg.png" }
603		693
604	Example: take the screen background and align it, giving the illusion of	694	Example: take the screen background and align it, giving the illusion of
605	transparency as long as the window isn't in front of other windows.	695	transparency as long as the window isn't in front of other windows.
606		696
607	rootalign root	697	rootalign root
…		…
632		722
633	sub rootalign($) {	723	sub rootalign($) {
634	move -TX, -TY, $_[0]	724	move -TX, -TY, $_[0]
635	}	725	}
636		726
		727	=item rotate $center_x, $center_y, $degrees, $img
		728
		729	Rotates the image clockwise by C<$degrees> degrees, around the point at
		730	C<$center_x> and C<$center_y> (specified as factor of image width/height).
		731
		732	Example: rotate the image by 90 degrees around it's center.
		733
		734	rotate 0.5, 0.5, 90, keep { load "$HOME/mybg.png" }
		735
		736	=cut
		737
		738	sub rotate($$$$) {
		739	my $img = pop;
		740	$img->rotate (
		741	$_[0] * ($img->w + $img->x),
		742	$_[1] * ($img->h + $img->y),
		743	$_[2] * (3.14159265 / 180),
		744	)
		745	}
		746
637	=back	747	=back
638		748
639	=head2 COLOUR MODIFICATIONS	749	=head2 COLOUR MODIFICATIONS
640		750
641	The following operators change the pixels of the image.	751	The following operators change the pixels of the image.
642		752
643	=over 4	753	=over 4
		754
		755	=item tint $color, $img
		756
		757	Tints the image in the given colour.
		758
		759	Example: tint the image red.
		760
		761	tint "red", load "rgb.png"
		762
		763	Example: the same, but specify the colour by component.
		764
		765	tint [1, 0, 0], load "rgb.png"
		766
		767	=cut
		768
		769	sub tint($$) {
		770	$_[1]->tint ($_[0])
		771	}
644		772
645	=item contrast $factor, $img	773	=item contrast $factor, $img
646		774
647	=item contrast $r, $g, $b, $img	775	=item contrast $r, $g, $b, $img
648		776
…		…
675		803
676	Values less than 0 reduce brightness, while values larger than 0 increase	804	Values less than 0 reduce brightness, while values larger than 0 increase
677	it. Useful range is from -1 to 1 - the former results in a black, the	805	it. Useful range is from -1 to 1 - the former results in a black, the
678	latter in a white picture.	806	latter in a white picture.
679		807
680	Due to idiosynchrasies in the underlying XRender extension, biases less	808	Due to idiosyncrasies in the underlying XRender extension, biases less
681	than zero can be I<very> slow.	809	than zero can be I<very> slow.
682		810
683	=cut	811	=cut
684		812
685	sub contrast($$;$$;$) {	813	sub contrast($$;$$;$) {
…		…
723	sub blur($$;$) {	851	sub blur($$;$) {
724	my $img = pop;	852	my $img = pop;
725	$img->blur ($_[0], @_ >= 2 ? $_[1] : $_[0])	853	$img->blur ($_[0], @_ >= 2 ? $_[1] : $_[0])
726	}	854	}
727		855
728	=item rotate $new_width, $new_height, $center_x, $center_y, $degrees
729
730	Rotates the image by C<$degrees> degrees, counter-clockwise, around the
731	pointer at C<$center_x> and C<$center_y> (specified as factor of image
732	width/height), generating a new image with width C<$new_width> and height
733	C<$new_height>.
734
735	#TODO# new width, height, maybe more operators?
736
737	Example: rotate the image by 90 degrees
738
739	=cut
740
741	sub rotate($$$$$$) {
742	my $img = pop;
743	$img->rotate (
744	$_[0],
745	$_[1],
746	$_[2] * $img->w,
747	$_[3] * $img->h,
748	$_[4] * (3.14159265 / 180),
749	)
750	}
751
752	=back	856	=back
753		857
		858	=head2 OTHER STUFF
		859
		860	Anything that didn't fit any of the other categories, even after applying
		861	force and closing our eyes.
		862
		863	=over 4
		864
		865	=item keep { ... }
		866
		867	This operator takes a code block as argument, that is, one or more
		868	statements enclosed by braces.
		869
		870	The trick is that this code block is only evaluated when the outcome
		871	changes - on other calls the C<keep> simply returns the image it computed
		872	previously (yes, it should only be used with images). Or in other words,
		873	C<keep> I<caches> the result of the code block so it doesn't need to be
		874	computed again.
		875
		876	This can be extremely useful to avoid redoing slow operations - for
		877	example, if your background expression takes the root background, blurs it
		878	and then root-aligns it it would have to blur the root background on every
		879	window move or resize.
		880
		881	Another example is C<load>, which can be quite slow.
		882
		883	In fact, urxvt itself encloses the whole expression in some kind of
		884	C<keep> block so it only is reevaluated as required.
		885
		886	Putting the blur into a C<keep> block will make sure the blur is only done
		887	once, while the C<rootalign> is still done each time the window moves.
		888
		889	rootlign keep { blur 10, root }
		890
		891	This leaves the question of how to force reevaluation of the block,
		892	in case the root background changes: If expression inside the block
		893	is sensitive to some event (root background changes, window geometry
		894	changes), then it will be reevaluated automatically as needed.
		895
		896	=cut
		897
		898	sub keep(&) {
		899	my $id = $_[0]+0;
		900
		901	local $frame = $self->{frame_cache}{$id} \|\|= [$frame];
		902
		903	unless ($frame->[FR_CACHE]) {
		904	$frame->[FR_CACHE] = [ $_[0]() ];
		905
		906	my $self = $self;
		907	my $frame = $frame;
		908	Scalar::Util::weaken $frame;
		909	$self->compile_frame ($frame, sub {
		910	# clear this frame cache, also for all parents
		911	for (my $frame = $frame; $frame; $frame = $frame->[0]) {
		912	undef $frame->[FR_CACHE];
		913	}
		914
		915	$self->recalculate;
		916	});
		917	};
		918
		919	# in scalar context we always return the first original result, which
		920	# is not quite how perl works.
		921	wantarray
		922	? @{ $frame->[FR_CACHE] }
		923	: $frame->[FR_CACHE][0]
		924	}
		925
		926	# sub keep_clear() {
		927	# delete $self->{frame_cache};
		928	# }
		929
		930	=back
		931
754	=cut	932	=cut
755		933
756	}	934	}
757		935
758	sub parse_expr {	936	sub parse_expr {
759	my $expr = eval "sub {\npackage urxvt::bgdsl;\n#line 0 'background expression'\n$_[0]\n}";	937	my $expr = eval
		938	"sub {\n"
		939	. "package urxvt::bgdsl;\n"
		940	. "#line 0 'background expression'\n"
		941	. "$_[0]\n"
		942	. "}";
760	die if $@;	943	die if $@;
761	$expr	944	$expr
762	}	945	}
763		946
764	# compiles a parsed expression	947	# compiles a parsed expression
765	sub set_expr {	948	sub set_expr {
766	my ($self, $expr) = @_;	949	my ($self, $expr) = @_;
767		950
		951	$self->{root} = [];
768	$self->{expr} = $expr;	952	$self->{expr} = $expr;
769	$self->recalculate;	953	$self->recalculate;
		954	}
		955
		956	# takes a hash of sensitivity indicators and installs watchers
		957	sub compile_frame {
		958	my ($self, $frame, $cb) = @_;
		959
		960	my $state = $frame->[urxvt::bgdsl::FR_STATE] \|\|= {};
		961	my $again = $frame->[urxvt::bgdsl::FR_AGAIN];
		962
		963	# don't keep stuff alive
		964	Scalar::Util::weaken $state;
		965
		966	if ($again->{nested}) {
		967	$state->{nested} = 1;
		968	} else {
		969	delete $state->{nested};
		970	}
		971
		972	if (my $interval = $again->{time}) {
		973	$state->{time} = [$interval, urxvt::timer->new->after ($interval)->interval ($interval)]
		974	if $state->{time}[0] != $interval;
		975
		976	# callback might have changed, although we could just rule that out
		977	$state->{time}[1]->cb (sub {
		978	++$state->{counter};
		979	$cb->();
		980	});
		981	} else {
		982	delete $state->{time};
		983	}
		984
		985	if ($again->{position}) {
		986	$state->{position} = $self->on (position_change => $cb);
		987	} else {
		988	delete $state->{position};
		989	}
		990
		991	if ($again->{size}) {
		992	$state->{size} = $self->on (size_change => $cb);
		993	} else {
		994	delete $state->{size};
		995	}
		996
		997	if ($again->{rootpmap}) {
		998	$state->{rootpmap} = $self->on (rootpmap_change => $cb);
		999	} else {
		1000	delete $state->{rootpmap};
		1001	}
770	}	1002	}
771		1003
772	# evaluate the current bg expression	1004	# evaluate the current bg expression
773	sub recalculate {	1005	sub recalculate {
774	my ($arg_self) = @_;	1006	my ($arg_self) = @_;
…		…
784		1016
785	$arg_self->{next_refresh} = urxvt::NOW + $MIN_INTERVAL;	1017	$arg_self->{next_refresh} = urxvt::NOW + $MIN_INTERVAL;
786		1018
787	# set environment to evaluate user expression	1019	# set environment to evaluate user expression
788		1020
789	local $self = $arg_self;	1021	local $self = $arg_self;
790
791	local $HOME = $ENV{HOME};	1022	local $HOME = $ENV{HOME};
792	local $old = $self->{state};	1023	local $frame = [];
793	local $new = my $state = $self->{state} = {};
794		1024
795	($x, $y, $w, $h) =
796	$self->background_geometry ($self->{border});	1025	($x, $y, $w, $h) = $self->background_geometry ($self->{border});
797		1026
798	# evaluate user expression	1027	# evaluate user expression
799		1028
800	my $img = eval { $self->{expr}->() };	1029	my @img = eval { $self->{expr}->() };
801	warn $@ if $@;#d#	1030	die $@ if $@;
802	die "background-expr did not return an image.\n" if !UNIVERSAL::isa $img, "urxvt::img";	1031	die "background-expr did not return anything.\n" unless @img;
		1032	die "background-expr: expected image(s), got something else.\n"
		1033	if grep { !UNIVERSAL::isa $_, "urxvt::img" } @img;
803		1034
804	$state->{size_sensitive} = 1	1035	my $img = urxvt::bgdsl::merge @img;
		1036
		1037	$frame->[FR_AGAIN]{size} = 1
805	if $img->repeat_mode != urxvt::RepeatNormal;	1038	if $img->repeat_mode != urxvt::RepeatNormal;
806		1039
807	# if the expression is sensitive to external events, prepare reevaluation then	1040	# if the expression is sensitive to external events, prepare reevaluation then
808		1041	$self->compile_frame ($frame, sub { $arg_self->recalculate });
809	my $repeat;
810
811	if (my $again = $state->{again}) {
812	$repeat = 1;
813	my $self = $self;
814	$state->{timer} = $again == $old->{again}
815	? $old->{timer}
816	: urxvt::timer->new->after ($again)->interval ($again)->cb (sub {
817	++$self->{counter};
818	$self->recalculate
819	});
820	}
821
822	if (delete $state->{position_sensitive}) {
823	$repeat = 1;
824	$self->enable (position_change => sub { $_[0]->recalculate });
825	} else {
826	$self->disable ("position_change");
827	}
828
829	if (delete $state->{size_sensitive}) {
830	$repeat = 1;
831	$self->enable (size_change => sub { $_[0]->recalculate });
832	} else {
833	$self->disable ("size_change");
834	}
835
836	if (delete $state->{rootpmap_sensitive}) {
837	$repeat = 1;
838	$self->enable (rootpmap_change => sub { $_[0]->recalculate });
839	} else {
840	$self->disable ("rootpmap_change");
841	}
842		1042
843	# clear stuff we no longer need	1043	# clear stuff we no longer need
844		1044
845	%$old = ();	1045	# unless (%{ $frame->[FR_STATE] }) {
846
847	unless ($repeat) {
848	delete $self->{state};	1046	# delete $self->{state};
849	delete $self->{expr};	1047	# delete $self->{expr};
850	}	1048	# }
851		1049
852	# set background pixmap	1050	# set background pixmap
853		1051
854	$self->set_background ($img, $self->{border});	1052	$self->set_background ($img, $self->{border});
855	$self->scr_recolour (0);	1053	$self->scr_recolour (0);

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Comparing rxvt-unicode/src/perl/background (file contents): Revision 1.49 by root, Sun Jun 10 15:29:18 2012 UTC vs. Revision 1.70 by root, Mon Jul 2 01:35:37 2012 UTC

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Comparing rxvt-unicode/src/perl/background (file contents):
Revision 1.49 by root, Sun Jun 10 15:29:18 2012 UTC vs.
Revision 1.70 by root, Mon Jul 2 01:35:37 2012 UTC