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

Comparing rxvt-unicode/src/perl/background (file contents):
Revision 1.48 by root, Sun Jun 10 15:01:14 2012 UTC vs.
Revision 1.82 by sf-exg, Sat Jan 19 10:04:34 2013 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
14		12
15	urxvt --background-expr 'background expression'	13	urxvt --background-expr 'background expression'
16	--background-border	14	--background-border
17	--background-interval seconds	15	--background-interval seconds
18		16
		17	=head1 QUICK AND DIRTY CHEAT SHEET
		18
		19	Just load a random jpeg image and tile the background with it without
		20	scaling or anything else:
		21
		22	load "/path/to/img.jpg"
		23
		24	The same, but use mirroring/reflection instead of tiling:
		25
		26	mirror load "/path/to/img.jpg"
		27
		28	Load an image and scale it to exactly fill the terminal window:
		29
		30	scale keep { load "/path/to/img.jpg" }
		31
		32	Implement pseudo-transparency by using a suitably-aligned root pixmap
		33	as window background:
		34
		35	rootalign root
		36
		37	Likewise, but keep a blurred copy:
		38
		39	rootalign keep { blur 10, root }
		40
19	=head1 DESCRIPTION	41	=head1 DESCRIPTION
20		42
21	This extension manages the terminal background by creating a picture that	43	This extension manages the terminal background by creating a picture that
22	is behind the text, replacing the normal background colour.	44	is behind the text, replacing the normal background colour.
23		45
…		…
28	to be as simple as possible.	50	to be as simple as possible.
29		51
30	For example, to load an image and scale it to the window size, you would	52	For example, to load an image and scale it to the window size, you would
31	use:	53	use:
32		54
33	urxvt --background-expr 'scale load "/path/to/mybg.png"'	55	urxvt --background-expr 'scale keep { load "/path/to/mybg.png" }'
34		56
35	Or specified as a X resource:	57	Or specified as a X resource:
36		58
37	URxvt.background-expr: scale load "/path/to/mybg.png"	59	URxvt.background-expr: scale keep { load "/path/to/mybg.png" }
38		60
39	=head1 THEORY OF OPERATION	61	=head1 THEORY OF OPERATION
40		62
41	At startup, just before the window is mapped for the first time, the	63	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	64	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	77	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	78	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	79	pixmap is replaced by another one the root background changes; or when the
58	timer elapses), then the expression will be evaluated again.	80	timer elapses), then the expression will be evaluated again.
59		81
60	For example, an expression such as C<scale load "$HOME/mybg.png"> scales the	82	For example, an expression such as C<scale keep { load "$HOME/mybg.png"
61	image to the window size, so it relies on the window size and will	83	}> 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	84	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	85	example. That ensures that the picture always fills the terminal, even
64	after it's size changes.	86	after its size changes.
65		87
66	=head2 EXPRESSIONS	88	=head2 EXPRESSIONS
67		89
68	Expressions are normal Perl expressions, in fact, they are Perl blocks -	90	Expressions are normal Perl expressions, in fact, they are Perl blocks -
69	which means you could use multiple lines and statements:	91	which means you could use multiple lines and statements:
70		92
		93	scale keep {
71	again 3600;	94	again 3600;
72	if (localtime now)[6]) {	95	if (localtime now)[6]) {
73	return scale load "$HOME/weekday.png";	96	return load "$HOME/weekday.png";
74	} else {	97	} else {
75	return scale load "$HOME/sunday.png";	98	return load "$HOME/sunday.png";
		99	}
76	}	100	}
77		101
78	This expression gets evaluated once per hour. It will set F<sunday.png> as	102	This inner expression is evaluated once per hour (and whenever the
		103	terminal window is resized). It sets F<sunday.png> as background on
79	background on Sundays, and F<weekday.png> on all other days.	104	Sundays, and F<weekday.png> on all other days.
80		105
81	Fortunately, we expect that most expressions will be much simpler, with	106	Fortunately, we expect that most expressions will be much simpler, with
82	little Perl knowledge needed.	107	little Perl knowledge needed.
83		108
84	Basically, you always start with a function that "generates" an image	109	Basically, you always start with a function that "generates" an image
…		…
117	horizontal and vertical dimensions. For example, this halves the image	142	horizontal and vertical dimensions. For example, this halves the image
118	width and doubles the image height:	143	width and doubles the image height:
119		144
120	scale 0.5, 2, load "$HOME/mypic.png"	145	scale 0.5, 2, load "$HOME/mypic.png"
121		146
122	Other effects than scalign are also readily available, for exmaple, you can	147	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:	148	because each time the terminal is resized, it loads the PNG image again
		149	and scales it. Scaling is usually fast (and unavoidable), but loading the
		150	image can be quite time consuming. This is where C<keep> comes in handy:
124		151
		152	scale 0.5, 2, keep { load "$HOME/mypic.png" }
		153
		154	The C<keep> operator executes all the statements inside the braces only
		155	once, or when it thinks the outcome might change. In other cases it
		156	returns the last value computed by the brace block.
		157
		158	This means that the C<load> is only executed once, which makes it much
		159	faster, but also means that more memory is being used, because the loaded
		160	image must be kept in memory at all times. In this expression, the
		161	trade-off is likely worth it.
		162
		163	But back to effects: Other effects than scaling are also readily
		164	available, for example, you can tile the image to fill the whole window,
		165	instead of resizing it:
		166
125	tile load "$HOME/mypic.png"	167	tile keep { load "$HOME/mypic.png" }
126		168
127	In fact, images returned by C<load> are in C<tile> mode by default, so the C<tile> operator	169	In fact, images returned by C<load> are in C<tile> mode by default, so the
128	is kind of superfluous.	170	C<tile> operator is kind of superfluous.
129		171
130	Another common effect is to mirror the image, so that the same edges touch:	172	Another common effect is to mirror the image, so that the same edges
		173	touch:
131		174
132	mirror load "$HOME/mypic.png"	175	mirror keep { load "$HOME/mypic.png" }
133		176
134	This is also a typical background expression:	177	Another common background expression is:
135		178
136	rootalign root	179	rootalign root
137		180
138	It first takes a snapshot of the screen background image, and then	181	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	182	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	183	left corner of the terminal window)- the result is pseudo-transparency:
141	moved around.	184	the image seems to be static while the window is moved around.
142		185
143	=head2 CYCLES AND CACHING	186	=head2 COLOUR SPECIFICATIONS
144		187
145	As has been mentioned before, the expression might be evaluated multiple	188	Whenever an operator expects a "colour", then this can be specified in one
146	times. Each time the expression is reevaluated, a new cycle is said to	189	of two ways: Either as string with an X11 colour specification, such as:
147	have begun. Many operators cache their results till the next cycle.
148		190
149	For example, the C<load> operator keeps a copy of the image. If it is	191	"red" # named colour
150	asked to load the same image on the next cycle it will not load it again,	192	"#f00" # simple rgb
151	but return the cached copy.	193	"[50]red" # red with 50% alpha
		194	"TekHVC:300/50/50" # anything goes
152		195
153	This only works for one cycle though, so as long as you load the same	196	OR as an array reference with one, three or four components:
154	image every time, it will always be cached, but when you load a different
155	image, it will forget about the first one.
156		197
157	This allows you to either speed things up by keeping multiple images in	198	[0.5] # 50% gray, 100% alpha
158	memory, or comserve memory by loading images more often.	199	[0.5, 0, 0] # dark red, no green or blur, 100% alpha
		200	[0.5, 0, 0, 0.7] # same with explicit 70% alpha
159		201
160	For example, you can keep two images in memory and use a random one like	202	=head2 CACHING AND SENSITIVITY
161	this:
162		203
163	my $img1 = load "img1.png";	204	Since some operations (such as C<load> and C<blur>) can take a long time,
164	my $img2 = load "img2.png";	205	caching results can be very important for a smooth operation. Caching can
165	(0.5 > rand) ? $img1 : $img2	206	also be useful to reduce memory usage, though, for example, when an image
		207	is cached by C<load>, it could be shared by multiple terminal windows
		208	running inside urxvtd.
166		209
167	Since both images are "loaded" every time the expression is evaluated,	210	=head3 C<keep { ... }> caching
168	they are always kept in memory. Contrast this version:
169		211
170	my $path1 = "img1.png";	212	The most important way to cache expensive operations is to use C<keep {
171	my $path2 = "img2.png";	213	... }>. The C<keep> operator takes a block of multiple statements enclosed
172	load ((0.5 > rand) ? $path1 : $path2)	214	by C<{}> and keeps the return value in memory.
173		215
174	Here, a path is selected randomly, and load is only called for one image,	216	An expression can be "sensitive" to various external events, such as
175	so keeps only one image in memory. If, on the next evaluation, luck	217	scaling or moving the window, root background changes and timers. Simply
176	decides to use the other path, then it will have to load that image again.	218	using an expression (such as C<scale> without parameters) that depends on
		219	certain changing values (called "variables"), or using those variables
		220	directly, will make an expression sensitive to these events - for example,
		221	using C<scale> or C<TW> will make the expression sensitive to the terminal
		222	size, and thus to resizing events.
		223
		224	When such an event happens, C<keep> will automatically trigger a
		225	reevaluation of the whole expression with the new value of the expression.
		226
		227	C<keep> is most useful for expensive operations, such as C<blur>:
		228
		229	rootalign keep { blur 20, root }
		230
		231	This makes a blurred copy of the root background once, and on subsequent
		232	calls, just root-aligns it. Since C<blur> is usually quite slow and
		233	C<rootalign> is quite fast, this trades extra memory (for the cached
		234	blurred pixmap) with speed (blur only needs to be redone when root
		235	changes).
		236
		237	=head3 C<load> caching
		238
		239	The C<load> operator itself does not keep images in memory, but as long as
		240	the image is still in memory, C<load> will use the in-memory image instead
		241	of loading it freshly from disk.
		242
		243	That means that this expression:
		244
		245	keep { load "$HOME/path..." }
		246
		247	Not only caches the image in memory, other terminal instances that try to
		248	C<load> it can reuse that in-memory copy.
177		249
178	=head1 REFERENCE	250	=head1 REFERENCE
179		251
180	=head2 COMMAND LINE SWITCHES	252	=head2 COMMAND LINE SWITCHES
181		253
…		…
193	Specifying this flag changes the behaviour, so that the image only	265	Specifying this flag changes the behaviour, so that the image only
194	replaces the background of the character area.	266	replaces the background of the character area.
195		267
196	=item --background-interval seconds	268	=item --background-interval seconds
197		269
198	Since some operations in the underlying XRender extension can effetively	270	Since some operations in the underlying XRender extension can effectively
199	freeze your X-server for prolonged time, this extension enforces a minimum	271	freeze your X-server for prolonged time, this extension enforces a minimum
200	time between updates, which is normally about 0.1 seconds.	272	time between updates, which is normally about 0.1 seconds.
201		273
202	If you want to do updates more often, you can decrease this safety	274	If you want to do updates more often, you can decrease this safety
203	interval with this switch.	275	interval with this switch.
204		276
205	=back	277	=back
206		278
207	=cut	279	=cut
208		280
		281	our %_IMG_CACHE;
209	our $HOME;	282	our $HOME;
210	our ($self, $old, $new);	283	our ($self, $frame);
211	our ($x, $y, $w, $h);	284	our ($x, $y, $w, $h);
212		285
213	# enforce at least this interval between updates	286	# enforce at least this interval between updates
214	our $MIN_INTERVAL = 6/59.951;	287	our $MIN_INTERVAL = 6/59.951;
215		288
216	{	289	{
217	package urxvt::bgdsl; # background language	290	package urxvt::bgdsl; # background language
		291
		292	sub FR_PARENT() { 0 } # parent frame, if any - must be #0
		293	sub FR_CACHE () { 1 } # cached values
		294	sub FR_AGAIN () { 2 } # what this expr is sensitive to
		295	sub FR_STATE () { 3 } # watchers etc.
218		296
219	use List::Util qw(min max sum shuffle);	297	use List::Util qw(min max sum shuffle);
220		298
221	=head2 PROVIDERS/GENERATORS	299	=head2 PROVIDERS/GENERATORS
222		300
…		…
229	=item load $path	307	=item load $path
230		308
231	Loads the image at the given C<$path>. The image is set to plane tiling	309	Loads the image at the given C<$path>. The image is set to plane tiling
232	mode.	310	mode.
233		311
234	Loaded images will be cached for one cycle.	312	If the image is already in memory (e.g. because another terminal instance
		313	uses it), then the in-memory copy us returned instead.
235		314
		315	=item load_uc $path
		316
		317	Load uncached - same as load, but does not cache the image, which means it
		318	is I<always> loaded from the filesystem again, even if another copy of it
		319	is in memory at the time.
		320
236	=cut	321	=cut
		322
		323	sub load_uc($) {
		324	$self->new_img_from_file ($_[0])
		325	}
237		326
238	sub load($) {	327	sub load($) {
239	my ($path) = @_;	328	my ($path) = @_;
240		329
241	$new->{load}{$path} = $old->{load}{$path} \|\| $self->new_img_from_file ($path);	330	$_IMG_CACHE{$path} \|\| do {
		331	my $img = load_uc $path;
		332	Scalar::Util::weaken ($_IMG_CACHE{$path} = $img);
		333	$img
		334	}
242	}	335	}
243		336
244	=item root	337	=item root
245		338
246	Returns the root window pixmap, that is, hopefully, the background image	339	Returns the root window pixmap, that is, hopefully, the background image
247	of your screen. The image is set to extend mode.	340	of your screen.
248		341
249	This function makes your expression root sensitive, that means it will be	342	This function makes your expression root sensitive, that means it will be
250	reevaluated when the bg image changes.	343	reevaluated when the bg image changes.
251		344
252	=cut	345	=cut
253		346
254	sub root() {	347	sub root() {
255	$new->{rootpmap_sensitive} = 1;	348	$frame->[FR_AGAIN]{rootpmap} = 1;
256	die "root op not supported, exg, we need you";	349	$self->new_img_from_root
257	}	350	}
258		351
259	=item solid $colour	352	=item solid $colour
260		353
261	=item solid $width, $height, $colour	354	=item solid $width, $height, $colour
…		…
269	=cut	362	=cut
270		363
271	sub solid($;$$) {	364	sub solid($;$$) {
272	my $colour = pop;	365	my $colour = pop;
273		366
274	my $img = $self->new_img (urxvt::PictStandardARGB32, $_[0] \|\| 1, $_[1] \|\| 1);	367	my $img = $self->new_img (urxvt::PictStandardARGB32, 0, 0, $_[0] \|\| 1, $_[1] \|\| 1);
275	$img->fill ($colour);	368	$img->fill ($colour);
276	$img	369	$img
277	}	370	}
278		371
279	=item clone $img	372	=item clone $img
…		…
283		376
284	=cut	377	=cut
285		378
286	sub clone($) {	379	sub clone($) {
287	$_[0]->clone	380	$_[0]->clone
		381	}
		382
		383	=item merge $img ...
		384
		385	Takes any number of images and merges them together, creating a single
		386	image containing them all. The tiling mode of the first image is used as
		387	the tiling mode of the resulting image.
		388
		389	This function is called automatically when an expression returns multiple
		390	images.
		391
		392	=cut
		393
		394	sub merge(@) {
		395	return $_[0] unless $#_;
		396
		397	# rather annoyingly clumsy, but optimisation is for another time
		398
		399	my $x0 = +1e9;
		400	my $y0 = +1e9;
		401	my $x1 = -1e9;
		402	my $y1 = -1e9;
		403
		404	for (@_) {
		405	my ($x, $y, $w, $h) = $_->geometry;
		406
		407	$x0 = $x if $x0 > $x;
		408	$y0 = $y if $y0 > $y;
		409
		410	$x += $w;
		411	$y += $h;
		412
		413	$x1 = $x if $x1 < $x;
		414	$y1 = $y if $y1 < $y;
		415	}
		416
		417	my $base = $self->new_img (urxvt::PictStandardARGB32, $x0, $y0, $x1 - $x0, $y1 - $y0);
		418	$base->repeat_mode ($_[0]->repeat_mode);
		419	$base->fill ([0, 0, 0, 0]);
		420
		421	$base->draw ($_)
		422	for @_;
		423
		424	$base
288	}	425	}
289		426
290	=back	427	=back
291		428
292	=head2 TILING MODES	429	=head2 TILING MODES
…		…
325	become transparent. This mode is most useful when you want to place an	462	become transparent. This mode is most useful when you want to place an
326	image over another image or the background colour while leaving all	463	image over another image or the background colour while leaving all
327	background pixels outside the image unchanged.	464	background pixels outside the image unchanged.
328		465
329	Example: load an image and display it in the upper left corner. The rest	466	Example: load an image and display it in the upper left corner. The rest
330	of the space is left "empty" (transparent or wahtever your compisotr does	467	of the space is left "empty" (transparent or whatever your compositor does
331	in alpha mode, else background colour).	468	in alpha mode, else background colour).
332		469
333	pad load "mybg.png"	470	pad load "mybg.png"
334		471
335	=item extend $img	472	=item extend $img
336		473
337	Extends the image over the whole plane, using the closest pixel in the	474	Extends the image over the whole plane, using the closest pixel in the
338	area outside the image. This mode is mostly useful when you more complex	475	area outside the image. This mode is mostly useful when you use more complex
339	filtering operations and want the pixels outside the image to have the	476	filtering operations and want the pixels outside the image to have the
340	same values as the pixels near the edge.	477	same values as the pixels near the edge.
341		478
342	Example: just for curiosity, how does this pixel extension stuff work?	479	Example: just for curiosity, how does this pixel extension stuff work?
343		480
…		…
392	Using these functions make your expression sensitive to window moves.	529	Using these functions make your expression sensitive to window moves.
393		530
394	These functions are mainly useful to align images to the root window.	531	These functions are mainly useful to align images to the root window.
395		532
396	Example: load an image and align it so it looks as if anchored to the	533	Example: load an image and align it so it looks as if anchored to the
397	background.	534	background (that's exactly what C<rootalign> does btw.):
398		535
399	move -TX, -TY, load "mybg.png"	536	move -TX, -TY, keep { load "mybg.png" }
400		537
401	=item TW	538	=item TW
		539
		540	=item TH
402		541
403	Return the width (C<TW>) and height (C<TH>) of the terminal window (the	542	Return the width (C<TW>) and height (C<TH>) of the terminal window (the
404	terminal window is the full window by default, and the character area only	543	terminal window is the full window by default, and the character area only
405	when in border-respect mode).	544	when in border-respect mode).
406		545
…		…
410	the window size to conserve memory.	549	the window size to conserve memory.
411		550
412	Example: take the screen background, clip it to the window size, blur it a	551	Example: take the screen background, clip it to the window size, blur it a
413	bit, align it to the window position and use it as background.	552	bit, align it to the window position and use it as background.
414		553
415	clip move -TX, -TY, blur 5, root	554	clip move -TX, -TY, keep { blur 5, root }
416		555
417	=cut	556	=cut
418		557
419	sub TX() { $new->{position_sensitive} = 1; $x }	558	sub TX() { $frame->[FR_AGAIN]{position} = 1; $x }
420	sub TY() { $new->{position_sensitive} = 1; $y }	559	sub TY() { $frame->[FR_AGAIN]{position} = 1; $y }
421	sub TW() { $new->{size_sensitive} = 1; $w }	560	sub TW() { $frame->[FR_AGAIN]{size} = 1; $w }
422	sub TH() { $new->{size_sensitive} = 1; $h }	561	sub TH() { $frame->[FR_AGAIN]{size} = 1; $h }
423		562
424	=item now	563	=item now
425		564
426	Returns the current time as (fractional) seconds since the epoch.	565	Returns the current time as (fractional) seconds since the epoch.
427		566
…		…
434	C<$seconds> seconds.	573	C<$seconds> seconds.
435		574
436	Example: load some image and rotate it according to the time of day (as if it were	575	Example: load some image and rotate it according to the time of day (as if it were
437	the hour pointer of a clock). Update this image every minute.	576	the hour pointer of a clock). Update this image every minute.
438		577
		578	again 60;
439	again 60; rotate TW, TH, 50, 50, (now % 86400) * -720 / 86400, scale load "myclock.png"	579	rotate 50, 50, (now % 86400) * -72 / 8640, scale keep { load "myclock.png" }
440		580
441	=item counter $seconds	581	=item counter $seconds
442		582
443	Like C<again>, but also returns an increasing counter value, starting at	583	Like C<again>, but also returns an increasing counter value, starting at
444	0, which might be useful for some simple animation effects.	584	0, which might be useful for some simple animation effects.
…		…
446	=cut	586	=cut
447		587
448	sub now() { urxvt::NOW }	588	sub now() { urxvt::NOW }
449		589
450	sub again($) {	590	sub again($) {
451	$new->{again} = $_[0];	591	$frame->[FR_AGAIN]{time} = $_[0];
452	}	592	}
453		593
454	sub counter($) {	594	sub counter($) {
455	$new->{again} = $_[0];	595	$frame->[FR_AGAIN]{time} = $_[0];
456	$self->{counter} + 0	596	$frame->[FR_STATE]{counter} + 0
457	}	597	}
458		598
459	=back	599	=back
460		600
461	=head2 SHAPE CHANGING OPERATORS	601	=head2 SHAPE CHANGING OPERATORS
…		…
473	Clips an image to the given rectangle. If the rectangle is outside the	613	Clips an image to the given rectangle. If the rectangle is outside the
474	image area (e.g. when C<$x> or C<$y> are negative) or the rectangle is	614	image area (e.g. when C<$x> or C<$y> are negative) or the rectangle is
475	larger than the image, then the tiling mode defines how the extra pixels	615	larger than the image, then the tiling mode defines how the extra pixels
476	will be filled.	616	will be filled.
477		617
478	If C<$x> an C<$y> are missing, then C<0> is assumed for both.	618	If C<$x> and C<$y> are missing, then C<0> is assumed for both.
479		619
480	If C<$width> and C<$height> are missing, then the window size will be	620	If C<$width> and C<$height> are missing, then the window size will be
481	assumed.	621	assumed.
482		622
483	Example: load an image, blur it, and clip it to the window size to save	623	Example: load an image, blur it, and clip it to the window size to save
484	memory.	624	memory.
485		625
486	clip blur 10, load "mybg.png"	626	clip keep { blur 10, load "mybg.png" }
487		627
488	=cut	628	=cut
489		629
490	sub clip($;$$;$$) {	630	sub clip($;$$;$$) {
491	my $img = pop;	631	my $img = pop;
…		…
501	=item scale $width_factor, $height_factor, $img	641	=item scale $width_factor, $height_factor, $img
502		642
503	Scales the image by the given factors in horizontal	643	Scales the image by the given factors in horizontal
504	(C<$width>) and vertical (C<$height>) direction.	644	(C<$width>) and vertical (C<$height>) direction.
505		645
506	If only one factor is give, it is used for both directions.	646	If only one factor is given, it is used for both directions.
507		647
508	If no factors are given, scales the image to the window size without	648	If no factors are given, scales the image to the window size without
509	keeping aspect.	649	keeping aspect.
510		650
511	=item resize $width, $height, $img	651	=item resize $width, $height, $img
…		…
585	the terminal window (or the box specified by C<$width> and C<$height> if	725	the terminal window (or the box specified by C<$width> and C<$height> if
586	given).	726	given).
587		727
588	Example: load an image and center it.	728	Example: load an image and center it.
589		729
590	center pad load "mybg.png"	730	center keep { pad load "mybg.png" }
591		731
592	=item rootalign $img	732	=item rootalign $img
593		733
594	Moves the image so that it appears glued to the screen as opposed to the	734	Moves the image so that it appears glued to the screen as opposed to the
595	window. This gives the illusion of a larger area behind the window. It is	735	window. This gives the illusion of a larger area behind the window. It is
596	exactly equivalent to C<move -TX, -TY>, that is, it moves the image to the	736	exactly equivalent to C<move -TX, -TY>, that is, it moves the image to the
597	top left of the screen.	737	top left of the screen.
598		738
599	Example: load a background image, put it in mirror mode and root align it.	739	Example: load a background image, put it in mirror mode and root align it.
600		740
601	rootalign mirror load "mybg.png"	741	rootalign keep { mirror load "mybg.png" }
602		742
603	Example: take the screen background and align it, giving the illusion of	743	Example: take the screen background and align it, giving the illusion of
604	transparency as long as the window isn't in front of other windows.	744	transparency as long as the window isn't in front of other windows.
605		745
606	rootalign root	746	rootalign root
…		…
631		771
632	sub rootalign($) {	772	sub rootalign($) {
633	move -TX, -TY, $_[0]	773	move -TX, -TY, $_[0]
634	}	774	}
635		775
		776	=item rotate $center_x, $center_y, $degrees, $img
		777
		778	Rotates the image clockwise by C<$degrees> degrees, around the point at
		779	C<$center_x> and C<$center_y> (specified as factor of image width/height).
		780
		781	Example: rotate the image by 90 degrees around its center.
		782
		783	rotate 0.5, 0.5, 90, keep { load "$HOME/mybg.png" }
		784
		785	=cut
		786
		787	sub rotate($$$$) {
		788	my $img = pop;
		789	$img->rotate (
		790	$_[0] * ($img->w + $img->x),
		791	$_[1] * ($img->h + $img->y),
		792	$_[2] * (3.14159265 / 180),
		793	)
		794	}
		795
636	=back	796	=back
637		797
638	=head2 COLOUR MODIFICATIONS	798	=head2 COLOUR MODIFICATIONS
639		799
640	The following operators change the pixels of the image.	800	The following operators change the pixels of the image.
641		801
642	=over 4	802	=over 4
		803
		804	=item tint $color, $img
		805
		806	Tints the image in the given colour.
		807
		808	Example: tint the image red.
		809
		810	tint "red", load "rgb.png"
		811
		812	Example: the same, but specify the colour by component.
		813
		814	tint [1, 0, 0], load "rgb.png"
		815
		816	=cut
		817
		818	sub tint($$) {
		819	$_[1]->tint ($_[0])
		820	}
		821
		822	=item shade $factor, $img
		823
		824	Shade the image by the given factor.
		825
		826	=cut
		827
		828	sub shade($$) {
		829	$_[1]->shade ($_[0])
		830	}
643		831
644	=item contrast $factor, $img	832	=item contrast $factor, $img
645		833
646	=item contrast $r, $g, $b, $img	834	=item contrast $r, $g, $b, $img
647		835
…		…
674		862
675	Values less than 0 reduce brightness, while values larger than 0 increase	863	Values less than 0 reduce brightness, while values larger than 0 increase
676	it. Useful range is from -1 to 1 - the former results in a black, the	864	it. Useful range is from -1 to 1 - the former results in a black, the
677	latter in a white picture.	865	latter in a white picture.
678		866
679	Due to idiosynchrasies in the underlying XRender extension, biases less	867	Due to idiosyncrasies in the underlying XRender extension, biases less
680	than zero can be I<very> slow.	868	than zero can be I<very> slow.
		869
		870	You can also try the experimental(!) C<muladd> operator.
681		871
682	=cut	872	=cut
683		873
684	sub contrast($$;$$;$) {	874	sub contrast($$;$$;$) {
685	my $img = pop;	875	my $img = pop;
686	my ($r, $g, $b, $a) = @_;	876	my ($r, $g, $b, $a) = @_;
687		877
688	($g, $b) = ($r, $r) if @_ < 4;	878	($g, $b) = ($r, $r) if @_ < 3;
689	$a = 1 if @_ < 5;	879	$a = 1 if @_ < 4;
690		880
691	$img = $img->clone;	881	$img = $img->clone;
692	$img->contrast ($r, $g, $b, $a);	882	$img->contrast ($r, $g, $b, $a);
693	$img	883	$img
694	}	884	}
695		885
696	sub brightness($$;$$;$) {	886	sub brightness($$;$$;$) {
697	my $img = pop;	887	my $img = pop;
698	my ($r, $g, $b, $a) = @_;	888	my ($r, $g, $b, $a) = @_;
699		889
700	($g, $b) = ($r, $r) if @_ < 4;	890	($g, $b) = ($r, $r) if @_ < 3;
701	$a = 1 if @_ < 5;	891	$a = 1 if @_ < 4;
702		892
703	$img = $img->clone;	893	$img = $img->clone;
704	$img->brightness ($r, $g, $b, $a);	894	$img->brightness ($r, $g, $b, $a);
705	$img	895	$img
		896	}
		897
		898	=item muladd $mul, $add, $img # EXPERIMENTAL
		899
		900	First multiplies the pixels by C<$mul>, then adds C<$add>. This can be used
		901	to implement brightness and contrast at the same time, with a wider value
		902	range than contrast and brightness operators.
		903
		904	Due to numerous bugs in XRender implementations, it can also introduce a
		905	number of visual artifacts.
		906
		907	Example: increase contrast by a factor of C<$c> without changing image
		908	brightness too much.
		909
		910	muladd $c, (1 - $c) * 0.5, $img
		911
		912	=cut
		913
		914	sub muladd($$$) {
		915	$_[2]->muladd ($_[0], $_[1])
706	}	916	}
707		917
708	=item blur $radius, $img	918	=item blur $radius, $img
709		919
710	=item blur $radius_horz, $radius_vert, $img	920	=item blur $radius_horz, $radius_vert, $img
…		…
722	sub blur($$;$) {	932	sub blur($$;$) {
723	my $img = pop;	933	my $img = pop;
724	$img->blur ($_[0], @_ >= 2 ? $_[1] : $_[0])	934	$img->blur ($_[0], @_ >= 2 ? $_[1] : $_[0])
725	}	935	}
726		936
727	=item rotate $new_width, $new_height, $center_x, $center_y, $degrees
728
729	Rotates the image by C<$degrees> degrees, counter-clockwise, around the
730	pointer at C<$center_x> and C<$center_y> (specified as factor of image
731	width/height), generating a new image with width C<$new_width> and height
732	C<$new_height>.
733
734	#TODO# new width, height, maybe more operators?
735
736	Example: rotate the image by 90 degrees
737
738	=cut
739
740	sub rotate($$$$$$) {
741	my $img = pop;
742	$img->rotate (
743	$_[0],
744	$_[1],
745	$_[2] * $img->w,
746	$_[3] * $img->h,
747	$_[4] * (3.14159265 / 180),
748	)
749	}
750
751	=back	937	=back
752		938
		939	=head2 OTHER STUFF
		940
		941	Anything that didn't fit any of the other categories, even after applying
		942	force and closing our eyes.
		943
		944	=over 4
		945
		946	=item keep { ... }
		947
		948	This operator takes a code block as argument, that is, one or more
		949	statements enclosed by braces.
		950
		951	The trick is that this code block is only evaluated when the outcome
		952	changes - on other calls the C<keep> simply returns the image it computed
		953	previously (yes, it should only be used with images). Or in other words,
		954	C<keep> I<caches> the result of the code block so it doesn't need to be
		955	computed again.
		956
		957	This can be extremely useful to avoid redoing slow operations - for
		958	example, if your background expression takes the root background, blurs it
		959	and then root-aligns it it would have to blur the root background on every
		960	window move or resize.
		961
		962	Another example is C<load>, which can be quite slow.
		963
		964	In fact, urxvt itself encloses the whole expression in some kind of
		965	C<keep> block so it only is reevaluated as required.
		966
		967	Putting the blur into a C<keep> block will make sure the blur is only done
		968	once, while the C<rootalign> is still done each time the window moves.
		969
		970	rootalign keep { blur 10, root }
		971
		972	This leaves the question of how to force reevaluation of the block,
		973	in case the root background changes: If expression inside the block
		974	is sensitive to some event (root background changes, window geometry
		975	changes), then it will be reevaluated automatically as needed.
		976
		977	=cut
		978
		979	sub keep(&) {
		980	my $id = $_[0]+0;
		981
		982	local $frame = $self->{frame_cache}{$id} \|\|= [$frame];
		983
		984	unless ($frame->[FR_CACHE]) {
		985	$frame->[FR_CACHE] = [ $_[0]() ];
		986
		987	my $self = $self;
		988	my $frame = $frame;
		989	Scalar::Util::weaken $frame;
		990	$self->compile_frame ($frame, sub {
		991	# clear this frame cache, also for all parents
		992	for (my $frame = $frame; $frame; $frame = $frame->[0]) {
		993	undef $frame->[FR_CACHE];
		994	}
		995
		996	$self->recalculate;
		997	});
		998	};
		999
		1000	# in scalar context we always return the first original result, which
		1001	# is not quite how perl works.
		1002	wantarray
		1003	? @{ $frame->[FR_CACHE] }
		1004	: $frame->[FR_CACHE][0]
		1005	}
		1006
		1007	# sub keep_clear() {
		1008	# delete $self->{frame_cache};
		1009	# }
		1010
		1011	=back
		1012
753	=cut	1013	=cut
754		1014
755	}	1015	}
756		1016
757	sub parse_expr {	1017	sub parse_expr {
758	my $expr = eval "sub {\npackage urxvt::bgdsl;\n#line 0 'background expression'\n$_[0]\n}";	1018	my $expr = eval
		1019	"sub {\n"
		1020	. "package urxvt::bgdsl;\n"
		1021	. "#line 0 'background expression'\n"
		1022	. "$_[0]\n"
		1023	. "}";
759	die if $@;	1024	die if $@;
760	$expr	1025	$expr
761	}	1026	}
762		1027
763	# compiles a parsed expression	1028	# compiles a parsed expression
764	sub set_expr {	1029	sub set_expr {
765	my ($self, $expr) = @_;	1030	my ($self, $expr) = @_;
766		1031
		1032	$self->{root} = []; # the outermost frame
767	$self->{expr} = $expr;	1033	$self->{expr} = $expr;
768	$self->recalculate;	1034	$self->recalculate;
		1035	}
		1036
		1037	# takes a hash of sensitivity indicators and installs watchers
		1038	sub compile_frame {
		1039	my ($self, $frame, $cb) = @_;
		1040
		1041	my $state = $frame->[urxvt::bgdsl::FR_STATE] \|\|= {};
		1042	my $again = $frame->[urxvt::bgdsl::FR_AGAIN];
		1043
		1044	# don't keep stuff alive
		1045	Scalar::Util::weaken $state;
		1046
		1047	if ($again->{nested}) {
		1048	$state->{nested} = 1;
		1049	} else {
		1050	delete $state->{nested};
		1051	}
		1052
		1053	if (my $interval = $again->{time}) {
		1054	$state->{time} = [$interval, urxvt::timer->new->after ($interval)->interval ($interval)]
		1055	if $state->{time}[0] != $interval;
		1056
		1057	# callback might have changed, although we could just rule that out
		1058	$state->{time}[1]->cb (sub {
		1059	++$state->{counter};
		1060	$cb->();
		1061	});
		1062	} else {
		1063	delete $state->{time};
		1064	}
		1065
		1066	if ($again->{position}) {
		1067	$state->{position} = $self->on (position_change => $cb);
		1068	} else {
		1069	delete $state->{position};
		1070	}
		1071
		1072	if ($again->{size}) {
		1073	$state->{size} = $self->on (size_change => $cb);
		1074	} else {
		1075	delete $state->{size};
		1076	}
		1077
		1078	if ($again->{rootpmap}) {
		1079	$state->{rootpmap} = $self->on (rootpmap_change => $cb);
		1080	} else {
		1081	delete $state->{rootpmap};
		1082	}
769	}	1083	}
770		1084
771	# evaluate the current bg expression	1085	# evaluate the current bg expression
772	sub recalculate {	1086	sub recalculate {
773	my ($arg_self) = @_;	1087	my ($arg_self) = @_;
…		…
783		1097
784	$arg_self->{next_refresh} = urxvt::NOW + $MIN_INTERVAL;	1098	$arg_self->{next_refresh} = urxvt::NOW + $MIN_INTERVAL;
785		1099
786	# set environment to evaluate user expression	1100	# set environment to evaluate user expression
787		1101
788	local $self = $arg_self;	1102	local $self = $arg_self;
789
790	local $HOME = $ENV{HOME};	1103	local $HOME = $ENV{HOME};
791	local $old = $self->{state};	1104	local $frame = $self->{root};
792	local $new = my $state = $self->{state} = {};
793		1105
794	($x, $y, $w, $h) =
795	$self->background_geometry ($self->{border});	1106	($x, $y, $w, $h) = $self->background_geometry ($self->{border});
796		1107
797	# evaluate user expression	1108	# evaluate user expression
798		1109
799	my $img = eval { $self->{expr}->() };	1110	my @img = eval { $self->{expr}->() };
800	warn $@ if $@;#d#	1111	die $@ if $@;
801	die "background-expr did not return an image.\n" if !UNIVERSAL::isa $img, "urxvt::img";	1112	die "background-expr did not return anything.\n" unless @img;
		1113	die "background-expr: expected image(s), got something else.\n"
		1114	if grep { !UNIVERSAL::isa $_, "urxvt::img" } @img;
802		1115
803	$state->{size_sensitive} = 1	1116	my $img = urxvt::bgdsl::merge @img;
		1117
		1118	$frame->[FR_AGAIN]{size} = 1
804	if $img->repeat_mode != urxvt::RepeatNormal;	1119	if $img->repeat_mode != urxvt::RepeatNormal;
805		1120
806	# if the expression is sensitive to external events, prepare reevaluation then	1121	# if the expression is sensitive to external events, prepare reevaluation then
807		1122	$self->compile_frame ($frame, sub { $arg_self->recalculate });
808	my $repeat;
809
810	if (my $again = $state->{again}) {
811	$repeat = 1;
812	my $self = $self;
813	$state->{timer} = $again == $old->{again}
814	? $old->{timer}
815	: urxvt::timer->new->after ($again)->interval ($again)->cb (sub {
816	++$self->{counter};
817	$self->recalculate
818	});
819	}
820
821	if (delete $state->{position_sensitive}) {
822	$repeat = 1;
823	$self->enable (position_change => sub { $_[0]->recalculate });
824	} else {
825	$self->disable ("position_change");
826	}
827
828	if (delete $state->{size_sensitive}) {
829	$repeat = 1;
830	$self->enable (size_change => sub { $_[0]->recalculate });
831	} else {
832	$self->disable ("size_change");
833	}
834
835	if (delete $state->{rootpmap_sensitive}) {
836	$repeat = 1;
837	$self->enable (rootpmap_change => sub { $_[0]->recalculate });
838	} else {
839	$self->disable ("rootpmap_change");
840	}
841		1123
842	# clear stuff we no longer need	1124	# clear stuff we no longer need
843		1125
844	%$old = ();	1126	# unless (%{ $frame->[FR_STATE] }) {
845
846	unless ($repeat) {
847	delete $self->{state};	1127	# delete $self->{state};
848	delete $self->{expr};	1128	# delete $self->{expr};
849	}	1129	# }
850		1130
851	# set background pixmap	1131	# set background pixmap
852		1132
853	$self->set_background ($img, $self->{border});	1133	$self->set_background ($img, $self->{border});
854	$self->scr_recolour (0);	1134	$self->scr_recolour (0);

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Comparing rxvt-unicode/src/perl/background (file contents): Revision 1.48 by root, Sun Jun 10 15:01:14 2012 UTC vs. Revision 1.82 by sf-exg, Sat Jan 19 10:04:34 2013 UTC

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Comparing rxvt-unicode/src/perl/background (file contents):
Revision 1.48 by root, Sun Jun 10 15:01:14 2012 UTC vs.
Revision 1.82 by sf-exg, Sat Jan 19 10:04:34 2013 UTC