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Revision 1.41 by root, Fri Jun 8 22:21:48 2012 UTC vs.
Revision 1.98 by root, Tue Sep 17 20:38:14 2019 UTC

1	#! perl	1	#! perl
2		2
3	#:META:X_RESOURCE:%.expr:string:background expression	3	#:META:RESOURCE:%.expr:string:background expression
4	#:META:X_RESOURCE:%.border.:boolean:respect the terminal border	4	#:META:RESOURCE:%.border:boolean:respect the terminal border
5		5	#:META:RESOURCE:%.interval:seconds:minimum time between updates
6	#TODO: once, rootalign	6	#:META:RESOURCE:pixmap:file[;geom]:set image as background
		7	#:META:RESOURCE:backgroundPixmap:file[;geom]:set image as background
		8	#:META:RESOURCE:tr:boolean:set root pixmap as background
		9	#:META:RESOURCE:transparent:boolean:set root pixmap as background
		10	#:META:RESOURCE:tint:color:tint background with color
		11	#:META:RESOURCE:tintColor:color:tint background with color
		12	#:META:RESOURCE:sh:number:shade background by number %
		13	#:META:RESOURCE:shading:number:shade background by number %
		14	#:META:RESOURCE:blr:HxV:gaussian-blur background with radii
		15	#:META:RESOURCE:blurRadius:HxV:gaussian-blur background with radii
7		16
8	=head1 NAME	17	=head1 NAME
9		18
10	background - manage terminal background	19	background - manage terminal background
11		20
12	=head1 SYNOPSIS	21	=head1 SYNOPSIS
13		22
14	urxvt --background-expr 'background expression'	23	urxvt --background-expr 'background expression'
15	--background-border	24	--background-border
		25	--background-interval seconds
		26
		27	=head1 QUICK AND DIRTY CHEAT SHEET
		28
		29	Load a random jpeg image and tile the background with it without scaling
		30	or anything else:
		31
		32	load "/path/to/img.jpg"
		33
		34	The same, but use mirroring/reflection instead of tiling:
		35
		36	mirror load "/path/to/img.jpg"
		37
		38	Load an image and scale it to exactly fill the terminal window:
		39
		40	scale keep { load "/path/to/img.jpg" }
		41
		42	Implement pseudo-transparency by using a suitably-aligned root pixmap
		43	as window background:
		44
		45	rootalign root
		46
		47	Likewise, but keep a blurred copy:
		48
		49	rootalign keep { blur 10, root }
16		50
17	=head1 DESCRIPTION	51	=head1 DESCRIPTION
18		52
19	This extension manages the terminal background by creating a picture that	53	This extension manages the terminal background by creating a picture that
20	is behind the text, replacing the normal background colour.	54	is behind the text, replacing the normal background colour.
…		…
26	to be as simple as possible.	60	to be as simple as possible.
27		61
28	For example, to load an image and scale it to the window size, you would	62	For example, to load an image and scale it to the window size, you would
29	use:	63	use:
30		64
31	urxvt --background-expr 'scale load "/path/to/mybg.png"'	65	urxvt --background-expr 'scale keep { load "/path/to/mybg.png" }'
32		66
33	Or specified as a X resource:	67	Or specified as a X resource:
34		68
35	URxvt.background-expr: scale load "/path/to/mybg.png"	69	URxvt.background.expr: scale keep { load "/path/to/mybg.png" }
36		70
37	=head1 THEORY OF OPERATION	71	=head1 THEORY OF OPERATION
38		72
39	At startup, just before the window is mapped for the first time, the	73	At startup, just before the window is mapped for the first time, the
40	expression is evaluated and must yield an image. The image is then	74	expression is evaluated and must yield an image. The image is then
…		…
53	If any of the parameters that the expression relies on changes (when the	87	If any of the parameters that the expression relies on changes (when the
54	window is moved or resized, its position or size changes; when the root	88	window is moved or resized, its position or size changes; when the root
55	pixmap is replaced by another one the root background changes; or when the	89	pixmap is replaced by another one the root background changes; or when the
56	timer elapses), then the expression will be evaluated again.	90	timer elapses), then the expression will be evaluated again.
57		91
58	For example, an expression such as C<scale load "$HOME/mybg.png"> scales the	92	For example, an expression such as C<scale keep { load "$HOME/mybg.png"
59	image to the window size, so it relies on the window size and will	93	}> scales the image to the window size, so it relies on the window size
60	be reevaluated each time it is changed, but not when it moves for	94	and will be reevaluated each time it is changed, but not when it moves for
61	example. That ensures that the picture always fills the terminal, even	95	example. That ensures that the picture always fills the terminal, even
62	after it's size changes.	96	after its size changes.
63		97
64	=head2 EXPRESSIONS	98	=head2 EXPRESSIONS
65		99
66	Expressions are normal Perl expressions, in fact, they are Perl blocks -	100	Expressions are normal Perl expressions, in fact, they are Perl blocks -
67	which means you could use multiple lines and statements:	101	which means you could use multiple lines and statements:
68		102
		103	scale keep {
69	again 3600;	104	again 3600;
70	if (localtime now)[6]) {	105	if (localtime now)[6]) {
71	return scale load "$HOME/weekday.png";	106	return load "$HOME/weekday.png";
72	} else {	107	} else {
73	return scale load "$HOME/sunday.png";	108	return load "$HOME/sunday.png";
		109	}
74	}	110	}
75		111
76	This expression gets evaluated once per hour. It will set F<sunday.png> as	112	This inner expression is evaluated once per hour (and whenever the
		113	terminal window is resized). It sets F<sunday.png> as background on
77	background on Sundays, and F<weekday.png> on all other days.	114	Sundays, and F<weekday.png> on all other days.
78		115
79	Fortunately, we expect that most expressions will be much simpler, with	116	Fortunately, we expect that most expressions will be much simpler, with
80	little Perl knowledge needed.	117	little Perl knowledge needed.
81		118
82	Basically, you always start with a function that "generates" an image	119	Basically, you always start with a function that "generates" an image
…		…
99	its result becomes the argument to the C<scale> function.	136	its result becomes the argument to the C<scale> function.
100		137
101	Many operators also allow some parameters preceding the input image	138	Many operators also allow some parameters preceding the input image
102	that modify its behaviour. For example, C<scale> without any additional	139	that modify its behaviour. For example, C<scale> without any additional
103	arguments scales the image to size of the terminal window. If you specify	140	arguments scales the image to size of the terminal window. If you specify
104	an additional argument, it uses it as a percentage:	141	an additional argument, it uses it as a scale factor (multiply by 100 to
		142	get a percentage):
105		143
106	scale 200, load "$HOME/mypic.png"	144	scale 2, load "$HOME/mypic.png"
107		145
108	This enlarges the image by a factor of 2 (200%). As you can see, C<scale>	146	This enlarges the image by a factor of 2 (200%). As you can see, C<scale>
109	has now two arguments, the C<200> and the C<load> expression, while	147	has now two arguments, the C<2> and the C<load> expression, while
110	C<load> only has one argument. Arguments are separated from each other by	148	C<load> only has one argument. Arguments are separated from each other by
111	commas.	149	commas.
112		150
113	Scale also accepts two arguments, which are then separate factors for both	151	Scale also accepts two arguments, which are then separate factors for both
114	horizontal and vertical dimensions. For example, this halves the image	152	horizontal and vertical dimensions. For example, this halves the image
115	width and doubles the image height:	153	width and doubles the image height:
116		154
117	scale 50, 200, load "$HOME/mypic.png"	155	scale 0.5, 2, load "$HOME/mypic.png"
118		156
119	Other effects than scalign are also readily available, for exmaple, you can	157	IF you try out these expressions, you might suffer from some sluggishness,
120	tile the image to fill the whole window, instead of resizing it:	158	because each time the terminal is resized, it loads the PNG image again
		159	and scales it. Scaling is usually fast (and unavoidable), but loading the
		160	image can be quite time consuming. This is where C<keep> comes in handy:
121		161
		162	scale 0.5, 2, keep { load "$HOME/mypic.png" }
		163
		164	The C<keep> operator executes all the statements inside the braces only
		165	once, or when it thinks the outcome might change. In other cases it
		166	returns the last value computed by the brace block.
		167
		168	This means that the C<load> is only executed once, which makes it much
		169	faster, but also means that more memory is being used, because the loaded
		170	image must be kept in memory at all times. In this expression, the
		171	trade-off is likely worth it.
		172
		173	But back to effects: Other effects than scaling are also readily
		174	available, for example, you can tile the image to fill the whole window,
		175	instead of resizing it:
		176
122	tile load "$HOME/mypic.png"	177	tile keep { load "$HOME/mypic.png" }
123		178
124	In fact, images returned by C<load> are in C<tile> mode by default, so the C<tile> operator	179	In fact, images returned by C<load> are in C<tile> mode by default, so the
125	is kind of superfluous.	180	C<tile> operator is kind of superfluous.
126		181
127	Another common effect is to mirror the image, so that the same edges touch:	182	Another common effect is to mirror the image, so that the same edges
		183	touch:
128		184
129	mirror load "$HOME/mypic.png"	185	mirror keep { load "$HOME/mypic.png" }
130		186
131	This is also a typical background expression:	187	Another common background expression is:
132		188
133	rootalign root	189	rootalign root
134		190
135	It first takes a snapshot of the screen background image, and then	191	This one first takes a snapshot of the screen background image, and then
136	moves it to the upper left corner of the screen - the result is	192	moves it to the upper left corner of the screen (as opposed to the upper
137	pseudo-transparency, as the image seems to be static while the window is	193	left corner of the terminal window)- the result is pseudo-transparency:
138	moved around.	194	the image seems to be static while the window is moved around.
139		195
140	=head2 CYCLES AND CACHING	196	=head2 COLOUR SPECIFICATIONS
141		197
142	As has been mentioned before, the expression might be evaluated multiple	198	Whenever an operator expects a "colour", then this can be specified in one
143	times. Each time the expression is reevaluated, a new cycle is said to	199	of two ways: Either as string with an X11 colour specification, such as:
144	have begun. Many operators cache their results till the next cycle.
145		200
146	For example, the C<load> operator keeps a copy of the image. If it is	201	"red" # named colour
147	asked to load the same image on the next cycle it will not load it again,	202	"#f00" # simple rgb
148	but return the cached copy.	203	"[50]red" # red with 50% alpha
		204	"TekHVC:300/50/50" # anything goes
149		205
150	This only works for one cycle though, so as long as you load the same	206	OR as an array reference with one, three or four components:
151	image every time, it will always be cached, but when you load a different
152	image, it will forget about the first one.
153		207
154	This allows you to either speed things up by keeping multiple images in	208	[0.5] # 50% gray, 100% alpha
155	memory, or comserve memory by loading images more often.	209	[0.5, 0, 0] # dark red, no green or blur, 100% alpha
		210	[0.5, 0, 0, 0.7] # same with explicit 70% alpha
156		211
157	For example, you can keep two images in memory and use a random one like	212	=head2 CACHING AND SENSITIVITY
158	this:
159		213
160	my $img1 = load "img1.png";	214	Since some operations (such as C<load> and C<blur>) can take a long time,
161	my $img2 = load "img2.png";	215	caching results can be very important for a smooth operation. Caching can
162	(0.5 > rand) ? $img1 : $img2	216	also be useful to reduce memory usage, though, for example, when an image
		217	is cached by C<load>, it could be shared by multiple terminal windows
		218	running inside urxvtd.
163		219
164	Since both images are "loaded" every time the expression is evaluated,	220	=head3 C<keep { ... }> caching
165	they are always kept in memory. Contrast this version:
166		221
167	my $path1 = "img1.png";	222	The most important way to cache expensive operations is to use C<keep {
168	my $path2 = "img2.png";	223	... }>. The C<keep> operator takes a block of multiple statements enclosed
169	load ((0.5 > rand) ? $path1 : $path2)	224	by C<{}> and keeps the return value in memory.
170		225
171	Here, a path is selected randomly, and load is only called for one image,	226	An expression can be "sensitive" to various external events, such as
172	so keeps only one image in memory. If, on the next evaluation, luck	227	scaling or moving the window, root background changes and timers. Simply
173	decides to use the other path, then it will have to load that image again.	228	using an expression (such as C<scale> without parameters) that depends on
		229	certain changing values (called "variables"), or using those variables
		230	directly, will make an expression sensitive to these events - for example,
		231	using C<scale> or C<TW> will make the expression sensitive to the terminal
		232	size, and thus to resizing events.
		233
		234	When such an event happens, C<keep> will automatically trigger a
		235	reevaluation of the whole expression with the new value of the expression.
		236
		237	C<keep> is most useful for expensive operations, such as C<blur>:
		238
		239	rootalign keep { blur 20, root }
		240
		241	This makes a blurred copy of the root background once, and on subsequent
		242	calls, just root-aligns it. Since C<blur> is usually quite slow and
		243	C<rootalign> is quite fast, this trades extra memory (for the cached
		244	blurred pixmap) with speed (blur only needs to be redone when root
		245	changes).
		246
		247	=head3 C<load> caching
		248
		249	The C<load> operator itself does not keep images in memory, but as long as
		250	the image is still in memory, C<load> will use the in-memory image instead
		251	of loading it freshly from disk.
		252
		253	That means that this expression:
		254
		255	keep { load "$HOME/path..." }
		256
		257	Not only caches the image in memory, other terminal instances that try to
		258	C<load> it can reuse that in-memory copy.
174		259
175	=head1 REFERENCE	260	=head1 REFERENCE
176		261
177	=head2 COMMAND LINE SWITCHES	262	=head2 COMMAND LINE SWITCHES
178		263
…		…
188	overwriting borders and any other areas, such as the scrollbar.	273	overwriting borders and any other areas, such as the scrollbar.
189		274
190	Specifying this flag changes the behaviour, so that the image only	275	Specifying this flag changes the behaviour, so that the image only
191	replaces the background of the character area.	276	replaces the background of the character area.
192		277
		278	=item --background-interval seconds
		279
		280	Since some operations in the underlying XRender extension can effectively
		281	freeze your X-server for prolonged time, this extension enforces a minimum
		282	time between updates, which is normally about 0.1 seconds.
		283
		284	If you want to do updates more often, you can decrease this safety
		285	interval with this switch.
		286
193	=back	287	=back
194		288
195	=cut	289	=cut
196		290
		291	our %_IMG_CACHE;
197	our $HOME;	292	our $HOME;
198	our ($self, $old, $new);	293	our ($self, $frame);
199	our ($x, $y, $w, $h);	294	our ($x, $y, $w, $h, $focus);
200		295
201	# enforce at least this interval between updates	296	# enforce at least this interval between updates
202	our $MIN_INTERVAL = 1/100;	297	our $MIN_INTERVAL = 6/59.951;
203		298
204	{	299	{
205	package urxvt::bgdsl; # background language	300	package urxvt::bgdsl; # background language
		301
		302	sub FR_PARENT() { 0 } # parent frame, if any - must be #0
		303	sub FR_CACHE () { 1 } # cached values
		304	sub FR_AGAIN () { 2 } # what this expr is sensitive to
		305	sub FR_STATE () { 3 } # watchers etc.
		306
		307	use List::Util qw(min max sum shuffle);
206		308
207	=head2 PROVIDERS/GENERATORS	309	=head2 PROVIDERS/GENERATORS
208		310
209	These functions provide an image, by loading it from disk, grabbing it	311	These functions provide an image, by loading it from disk, grabbing it
210	from the root screen or by simply generating it. They are used as starting	312	from the root screen or by simply generating it. They are used as starting
…		…
215	=item load $path	317	=item load $path
216		318
217	Loads the image at the given C<$path>. The image is set to plane tiling	319	Loads the image at the given C<$path>. The image is set to plane tiling
218	mode.	320	mode.
219		321
220	Loaded images will be cached for one cycle.	322	If the image is already in memory (e.g. because another terminal instance
		323	uses it), then the in-memory copy is returned instead.
221		324
		325	=item load_uc $path
		326
		327	Load uncached - same as load, but does not cache the image, which means it
		328	is I<always> loaded from the filesystem again, even if another copy of it
		329	is in memory at the time.
		330
222	=cut	331	=cut
		332
		333	sub load_uc($) {
		334	$self->new_img_from_file ($_[0])
		335	}
223		336
224	sub load($) {	337	sub load($) {
225	my ($path) = @_;	338	my ($path) = @_;
226		339
227	$new->{load}{$path} = $old->{load}{$path} || $self->new_img_from_file ($path);	340	$_IMG_CACHE{$path} || do {
		341	my $img = load_uc $path;
		342	Scalar::Util::weaken ($_IMG_CACHE{$path} = $img);
		343	$img
		344	}
228	}	345	}
229		346
230	=item root	347	=item root
231		348
232	Returns the root window pixmap, that is, hopefully, the background image	349	Returns the root window pixmap, that is, hopefully, the background image
233	of your screen. The image is set to extend mode.	350	of your screen.
234		351
235	This function makes your expression root sensitive, that means it will be	352	This function makes your expression root sensitive, that means it will be
236	reevaluated when the bg image changes.	353	reevaluated when the bg image changes.
237		354
238	=cut	355	=cut
239		356
240	sub root() {	357	sub root() {
241	$new->{rootpmap_sensitive} = 1;	358	$frame->[FR_AGAIN]{rootpmap} = 1;
242	die "root op not supported, exg, we need you";	359	$self->new_img_from_root
243	}	360	}
244		361
245	=item solid $colour	362	=item solid $colour
246		363
247	=item solid $width, $height, $colour	364	=item solid $width, $height, $colour
…		…
252	If C<$width> and C<$height> are omitted, it creates a 1x1 image, which is	369	If C<$width> and C<$height> are omitted, it creates a 1x1 image, which is
253	useful for solid backgrounds or for use in filtering effects.	370	useful for solid backgrounds or for use in filtering effects.
254		371
255	=cut	372	=cut
256		373
257	sub solid($$;$) {	374	sub solid($;$$) {
258	my $colour = pop;	375	my $colour = pop;
259		376
260	my $img = $self->new_img (urxvt::PictStandardARGB32, $_[0] || 1, $_[1] || 1);	377	my $img = $self->new_img (urxvt::PictStandardARGB32, 0, 0, $_[0] || 1, $_[1] || 1);
261	$img->fill ($colour);	378	$img->fill ($colour);
262	$img	379	$img
263	}	380	}
264		381
265	=back	382	=item clone $img
266		383
267	=head2 VARIABLES	384	Returns an exact copy of the image. This is useful if you want to have
		385	multiple copies of the same image to apply different effects to.
268		386
269	The following functions provide variable data such as the terminal window
270	dimensions. They are not (Perl-) variables, they jsut return stuff that
271	varies. Most of them make your expression sensitive to some events, for
272	example using C<TW> (terminal width) means your expression is evaluated
273	again when the terminal is resized.
274
275	=over 4
276
277	=item TX
278
279	=item TY
280
281	Return the X and Y coordinates of the terminal window (the terminal
282	window is the full window by default, and the character area only when in
283	border-respect mode).
284
285	Using these functions make your expression sensitive to window moves.
286
287	These functions are mainly useful to align images to the root window.
288
289	Example: load an image and align it so it looks as if anchored to the
290	background.
291
292	move -TX, -TY, load "mybg.png"
293
294	=item TW
295
296	Return the width (C<TW>) and height (C<TH>) of the terminal window (the
297	terminal window is the full window by default, and the character area only
298	when in border-respect mode).
299
300	Using these functions make your expression sensitive to window resizes.
301
302	These functions are mainly useful to scale images, or to clip images to
303	the window size to conserve memory.
304
305	Example: take the screen background, clip it to the window size, blur it a
306	bit, align it to the window position and use it as background.
307
308	clip move -TX, -TY, blur 5, root
309
310	=cut	387	=cut
311		388
312	sub TX() { $new->{position_sensitive} = 1; $x }
313	sub TY() { $new->{position_sensitive} = 1; $y }
314	sub TW() { $new->{size_sensitive} = 1; $w }
315	sub TH() { $new->{size_sensitive} = 1; $h }
316
317	=item now
318
319	Returns the current time as (fractional) seconds since the epoch.
320
321	Using this expression does I<not> make your expression sensitive to time,
322	but the next two functions do.
323
324	=item again $seconds
325
326	When this function is used the expression will be reevaluated again in
327	C<$seconds> seconds.
328
329	Example: load some image and rotate it according to the time of day (as if it were
330	the hour pointer of a clock). Update this image every minute.
331
332	again 60; rotate TW, TH, 50, 50, (now % 86400) * -720 / 86400, scale load "myclock.png"
333
334	=item counter $seconds
335
336	Like C<again>, but also returns an increasing counter value, starting at
337	0, which might be useful for some simple animation effects.
338
339	=cut
340
341	sub now() { urxvt::NOW }
342
343	sub again($) {
344	$new->{again} = $_[0];
345	}
346
347	sub counter($) {	389	sub clone($) {
348	$new->{again} = $_[0];	390	$_[0]->clone
349	$self->{counter} + 0	391	}
		392
		393	=item merge $img ...
		394
		395	Takes any number of images and merges them together, creating a single
		396	image containing them all. The tiling mode of the first image is used as
		397	the tiling mode of the resulting image.
		398
		399	This function is called automatically when an expression returns multiple
		400	images.
		401
		402	=cut
		403
		404	sub merge(@) {
		405	return $_[0] unless $#_;
		406
		407	# rather annoyingly clumsy, but optimisation is for another time
		408
		409	my $x0 = +1e9;
		410	my $y0 = +1e9;
		411	my $x1 = -1e9;
		412	my $y1 = -1e9;
		413
		414	for (@_) {
		415	my ($x, $y, $w, $h) = $_->geometry;
		416
		417	$x0 = $x if $x0 > $x;
		418	$y0 = $y if $y0 > $y;
		419
		420	$x += $w;
		421	$y += $h;
		422
		423	$x1 = $x if $x1 < $x;
		424	$y1 = $y if $y1 < $y;
		425	}
		426
		427	my $base = $self->new_img (urxvt::PictStandardARGB32, $x0, $y0, $x1 - $x0, $y1 - $y0);
		428	$base->repeat_mode ($_[0]->repeat_mode);
		429	$base->fill ([0, 0, 0, 0]);
		430
		431	$base->draw ($_)
		432	for @_;
		433
		434	$base
350	}	435	}
351		436
352	=back	437	=back
353		438
354	=head2 TILING MODES	439	=head2 TILING MODES
…		…
387	become transparent. This mode is most useful when you want to place an	472	become transparent. This mode is most useful when you want to place an
388	image over another image or the background colour while leaving all	473	image over another image or the background colour while leaving all
389	background pixels outside the image unchanged.	474	background pixels outside the image unchanged.
390		475
391	Example: load an image and display it in the upper left corner. The rest	476	Example: load an image and display it in the upper left corner. The rest
392	of the space is left "empty" (transparent or wahtever your compisotr does	477	of the space is left "empty" (transparent or whatever your compositor does
393	in alpha mode, else background colour).	478	in alpha mode, else background colour).
394		479
395	pad load "mybg.png"	480	pad load "mybg.png"
396		481
397	=item extend $img	482	=item extend $img
398		483
399	Extends the image over the whole plane, using the closest pixel in the	484	Extends the image over the whole plane, using the closest pixel in the
400	area outside the image. This mode is mostly useful when you more complex	485	area outside the image. This mode is mostly useful when you use more complex
401	filtering operations and want the pixels outside the image to have the	486	filtering operations and want the pixels outside the image to have the
402	same values as the pixels near the edge.	487	same values as the pixels near the edge.
403		488
404	Example: just for curiosity, how does this pixel extension stuff work?	489	Example: just for curiosity, how does this pixel extension stuff work?
405		490
…		…
431	$img	516	$img
432	}	517	}
433		518
434	=back	519	=back
435		520
436	=head2 PIXEL OPERATORS	521	=head2 VARIABLE VALUES
437		522
438	The following operators modify the image pixels in various ways.	523	The following functions provide variable data such as the terminal window
		524	dimensions. They are not (Perl-) variables, they just return stuff that
		525	varies. Most of them make your expression sensitive to some events, for
		526	example using C<TW> (terminal width) means your expression is evaluated
		527	again when the terminal is resized.
439		528
440	=over 4	529	=over 4
441		530
442	=item clone $img	531	=item TX
443		532
444	Returns an exact copy of the image.	533	=item TY
445		534
446	=cut	535	Return the X and Y coordinates of the terminal window (the terminal
		536	window is the full window by default, and the character area only when in
		537	border-respect mode).
447		538
		539	Using these functions makes your expression sensitive to window moves.
		540
		541	These functions are mainly useful to align images to the root window.
		542
		543	Example: load an image and align it so it looks as if anchored to the
		544	background (that's exactly what C<rootalign> does btw.):
		545
		546	move -TX, -TY, keep { load "mybg.png" }
		547
		548	=item TW
		549
		550	=item TH
		551
		552	Return the width (C<TW>) and height (C<TH>) of the terminal window (the
		553	terminal window is the full window by default, and the character area only
		554	when in border-respect mode).
		555
		556	Using these functions makes your expression sensitive to window resizes.
		557
		558	These functions are mainly useful to scale images, or to clip images to
		559	the window size to conserve memory.
		560
		561	Example: take the screen background, clip it to the window size, blur it a
		562	bit, align it to the window position and use it as background.
		563
		564	clip move -TX, -TY, keep { blur 5, root }
		565
		566	=item FOCUS
		567
		568	Returns a boolean indicating whether the terminal window has keyboard
		569	focus, in which case it returns true.
		570
		571	Using this function makes your expression sensitive to focus changes.
		572
		573	A common use case is to fade the background image when the terminal loses
		574	focus, often together with the C<-fade> command line option. In fact,
		575	there is a special function for just that use case: C<focus_fade>.
		576
		577	Example: use two entirely different background images, depending on
		578	whether the window has focus.
		579
		580	FOCUS ? keep { load "has_focus.jpg" } : keep { load "no_focus.jpg" }
		581
		582	=cut
		583
		584	sub TX () { $frame->[FR_AGAIN]{position} = 1; $x }
		585	sub TY () { $frame->[FR_AGAIN]{position} = 1; $y }
		586	sub TW () { $frame->[FR_AGAIN]{size} = 1; $w }
		587	sub TH () { $frame->[FR_AGAIN]{size} = 1; $h }
		588	sub FOCUS() { $frame->[FR_AGAIN]{focus} = 1; $focus }
		589
		590	=item now
		591
		592	Returns the current time as (fractional) seconds since the epoch.
		593
		594	Using this expression does I<not> make your expression sensitive to time,
		595	but the next two functions do.
		596
		597	=item again $seconds
		598
		599	When this function is used the expression will be reevaluated again in
		600	C<$seconds> seconds.
		601
		602	Example: load some image and rotate it according to the time of day (as if it were
		603	the hour pointer of a clock). Update this image every minute.
		604
		605	again 60;
		606	rotate 50, 50, (now % 86400) * -72 / 8640, scale keep { load "myclock.png" }
		607
		608	=item counter $seconds
		609
		610	Like C<again>, but also returns an increasing counter value, starting at
		611	0, which might be useful for some simple animation effects.
		612
		613	=cut
		614
		615	sub now() { urxvt::NOW }
		616
		617	sub again($) {
		618	$frame->[FR_AGAIN]{time} = $_[0];
		619	}
		620
448	sub clone($) {	621	sub counter($) {
449	$_[0]->clone	622	$frame->[FR_AGAIN]{time} = $_[0];
		623	$frame->[FR_STATE]{counter} + 0
450	}	624	}
		625
		626	=back
		627
		628	=head2 SHAPE CHANGING OPERATORS
		629
		630	The following operators modify the shape, size or position of the image.
		631
		632	=over 4
451		633
452	=item clip $img	634	=item clip $img
453		635
454	=item clip $width, $height, $img	636	=item clip $width, $height, $img
455		637
…		…
458	Clips an image to the given rectangle. If the rectangle is outside the	640	Clips an image to the given rectangle. If the rectangle is outside the
459	image area (e.g. when C<$x> or C<$y> are negative) or the rectangle is	641	image area (e.g. when C<$x> or C<$y> are negative) or the rectangle is
460	larger than the image, then the tiling mode defines how the extra pixels	642	larger than the image, then the tiling mode defines how the extra pixels
461	will be filled.	643	will be filled.
462		644
463	If C<$x> an C<$y> are missing, then C<0> is assumed for both.	645	If C<$x> and C<$y> are missing, then C<0> is assumed for both.
464		646
465	If C<$width> and C<$height> are missing, then the window size will be	647	If C<$width> and C<$height> are missing, then the window size will be
466	assumed.	648	assumed.
467		649
468	Example: load an image, blur it, and clip it to the window size to save	650	Example: load an image, blur it, and clip it to the window size to save
469	memory.	651	memory.
470		652
471	clip blur 10, load "mybg.png"	653	clip keep { blur 10, load "mybg.png" }
472		654
473	=cut	655	=cut
474		656
475	sub clip($;$$;$$) {	657	sub clip($;$$;$$) {
476	my $img = pop;	658	my $img = pop;
…		…
479	$img->sub_rect ($_[0], $_[1], $w, $h)	661	$img->sub_rect ($_[0], $_[1], $w, $h)
480	}	662	}
481		663
482	=item scale $img	664	=item scale $img
483		665
484	=item scale $size_percent, $img	666	=item scale $size_factor, $img
485		667
486	=item scale $width_percent, $height_percent, $img	668	=item scale $width_factor, $height_factor, $img
487		669
488	Scales the image by the given percentages in horizontal	670	Scales the image by the given factors in horizontal
489	(C<$width_percent>) and vertical (C<$height_percent>) direction.	671	(C<$width>) and vertical (C<$height>) direction.
490		672
491	If only one percentage is give, it is used for both directions.	673	If only one factor is given, it is used for both directions.
492		674
493	If no percentages are given, scales the image to the window size without	675	If no factors are given, scales the image to the window size without
494	keeping aspect.	676	keeping aspect.
495		677
496	=item resize $width, $height, $img	678	=item resize $width, $height, $img
497		679
498	Resizes the image to exactly C<$width> times C<$height> pixels.	680	Resizes the image to exactly C<$width> times C<$height> pixels.
499		681
500	=cut	682	=item fit $img
501		683
502	#TODO: maximise, maximise_fill?	684	=item fit $width, $height, $img
		685
		686	Fits the image into the given C<$width> and C<$height> without changing
		687	aspect, or the terminal size. That means it will be shrunk or grown until
		688	the whole image fits into the given area, possibly leaving borders.
		689
		690	=item cover $img
		691
		692	=item cover $width, $height, $img
		693
		694	Similar to C<fit>, but shrinks or grows until all of the area is covered
		695	by the image, so instead of potentially leaving borders, it will cut off
		696	image data that doesn't fit.
		697
		698	=cut
503		699
504	sub scale($;$;$) {	700	sub scale($;$;$) {
505	my $img = pop;	701	my $img = pop;
506		702
507	@_ == 2 ? $img->scale ($_[0] * $img->w * 0.01, $_[1] * $img->h * 0.01)	703	@_ == 2 ? $img->scale ($_[0] * $img->w, $_[1] * $img->h)
508	: @_ ? $img->scale ($_[0] * $img->w * 0.01, $_[0] * $img->h * 0.01)	704	: @_ ? $img->scale ($_[0] * $img->w, $_[0] * $img->h)
509	: $img->scale (TW, TH)	705	: $img->scale (TW, TH)
510	}	706	}
511		707
512	sub resize($$$) {	708	sub resize($$$) {
513	my $img = pop;	709	my $img = pop;
514	$img->scale ($_[0], $_[1])	710	$img->scale ($_[0], $_[1])
515	}	711	}
516		712
		713	sub fit($;$$) {
		714	my $img = pop;
		715	my $w = ($_[0] || TW) / $img->w;
		716	my $h = ($_[1] || TH) / $img->h;
		717	scale +(min $w, $h), $img
		718	}
		719
		720	sub cover($;$$) {
		721	my $img = pop;
		722	my $w = ($_[0] || TW) / $img->w;
		723	my $h = ($_[1] || TH) / $img->h;
		724	scale +(max $w, $h), $img
		725	}
		726
517	=item move $dx, $dy, $img	727	=item move $dx, $dy, $img
518		728
519	Moves the image by C<$dx> pixels in the horizontal, and C<$dy> pixels in	729	Moves the image by C<$dx> pixels in the horizontal, and C<$dy> pixels in
520	the vertical.	730	the vertical.
521		731
522	Example: move the image right by 20 pixels and down by 30.	732	Example: move the image right by 20 pixels and down by 30.
523		733
524	move 20, 30, ...	734	move 20, 30, ...
		735
		736	=item align $xalign, $yalign, $img
		737
		738	Aligns the image according to a factor - C<0> means the image is moved to
		739	the left or top edge (for C<$xalign> or C<$yalign>), C<0.5> means it is
		740	exactly centered and C<1> means it touches the right or bottom edge.
		741
		742	Example: remove any visible border around an image, center it vertically but move
		743	it to the right hand side.
		744
		745	align 1, 0.5, pad $img
		746
		747	=item center $img
		748
		749	=item center $width, $height, $img
		750
		751	Centers the image, i.e. the center of the image is moved to the center of
		752	the terminal window (or the box specified by C<$width> and C<$height> if
		753	given).
		754
		755	Example: load an image and center it.
		756
		757	center keep { pad load "mybg.png" }
525		758
526	=item rootalign $img	759	=item rootalign $img
527		760
528	Moves the image so that it appears glued to the screen as opposed to the	761	Moves the image so that it appears glued to the screen as opposed to the
529	window. This gives the illusion of a larger area behind the window. It is	762	window. This gives the illusion of a larger area behind the window. It is
530	exactly equivalent to C<move -TX, -TY>, that is, it moves the image to the	763	exactly equivalent to C<move -TX, -TY>, that is, it moves the image to the
531	top left of the screen.	764	top left of the screen.
532		765
533	Example: load a background image, put it in mirror mode and root align it.	766	Example: load a background image, put it in mirror mode and root align it.
534		767
535	rootalign mirror load "mybg.png"	768	rootalign keep { mirror load "mybg.png" }
536		769
537	Example: take the screen background and align it, giving the illusion of	770	Example: take the screen background and align it, giving the illusion of
538	transparency as long as the window isn't in front of other windows.	771	transparency as long as the window isn't in front of other windows.
539		772
540	rootalign root	773	rootalign root
541		774
542	=cut	775	=cut
543		776
544	sub move($$;$) {	777	sub move($$;$) {
545	my $img = pop->clone;	778	my $img = pop->clone;
546	$img->move ($_[0], $_[1]);	779	$img->move ($_[0], $_[1]);
547	$img	780	$img
548	}	781	}
549		782
		783	sub align($;$$) {
		784	my $img = pop;
		785
		786	move $_[0] * (TW - $img->w),
		787	$_[1] * (TH - $img->h),
		788	$img
		789	}
		790
		791	sub center($;$$) {
		792	my $img = pop;
		793	my $w = $_[0] || TW;
		794	my $h = $_[1] || TH;
		795
		796	move 0.5 * ($w - $img->w), 0.5 * ($h - $img->h), $img
		797	}
		798
550	sub rootalign($) {	799	sub rootalign($) {
551	move -TX, -TY, $_[0]	800	move -TX, -TY, $_[0]
552	}	801	}
553		802
		803	=item rotate $center_x, $center_y, $degrees, $img
		804
		805	Rotates the image clockwise by C<$degrees> degrees, around the point at
		806	C<$center_x> and C<$center_y> (specified as factor of image width/height).
		807
		808	Example: rotate the image by 90 degrees around its center.
		809
		810	rotate 0.5, 0.5, 90, keep { load "$HOME/mybg.png" }
		811
		812	=cut
		813
		814	sub rotate($$$$) {
		815	my $img = pop;
		816	$img->rotate (
		817	$_[0] * ($img->w + $img->x),
		818	$_[1] * ($img->h + $img->y),
		819	$_[2] * (3.14159265 / 180),
		820	)
		821	}
		822
		823	=back
		824
		825	=head2 COLOUR MODIFICATIONS
		826
		827	The following operators change the pixels of the image.
		828
		829	=over 4
		830
		831	=item tint $color, $img
		832
		833	Tints the image in the given colour.
		834
		835	Example: tint the image red.
		836
		837	tint "red", load "rgb.png"
		838
		839	Example: the same, but specify the colour by component.
		840
		841	tint [1, 0, 0], load "rgb.png"
		842
		843	=cut
		844
		845	sub tint($$) {
		846	$_[1]->tint ($_[0])
		847	}
		848
		849	=item shade $factor, $img
		850
		851	Shade the image by the given factor.
		852
		853	=cut
		854
		855	sub shade($$) {
		856	$_[1]->shade ($_[0])
		857	}
		858
554	=item contrast $factor, $img	859	=item contrast $factor, $img
555		860
556	=item contrast $r, $g, $b, $img	861	=item contrast $r, $g, $b, $img
557		862
558	=item contrast $r, $g, $b, $a, $img	863	=item contrast $r, $g, $b, $a, $img
559		864
560	Adjusts the I<contrast> of an image.	865	Adjusts the I<contrast> of an image.
561		866
562	#TODO#	867	The first form applies a single C<$factor> to red, green and blue, the
		868	second form applies separate factors to each colour channel, and the last
		869	form includes the alpha channel.
563		870
		871	Values from 0 to 1 lower the contrast, values higher than 1 increase the
		872	contrast.
		873
		874	Due to limitations in the underlying XRender extension, lowering contrast
		875	also reduces brightness, while increasing contrast currently also
		876	increases brightness.
		877
564	=item brightness $factor, $img	878	=item brightness $bias, $img
565		879
566	=item brightness $r, $g, $b, $img	880	=item brightness $r, $g, $b, $img
567		881
568	=item brightness $r, $g, $b, $a, $img	882	=item brightness $r, $g, $b, $a, $img
569		883
570	Adjusts the brightness of an image.	884	Adjusts the brightness of an image.
		885
		886	The first form applies a single C<$bias> to red, green and blue, the
		887	second form applies separate biases to each colour channel, and the last
		888	form includes the alpha channel.
		889
		890	Values less than 0 reduce brightness, while values larger than 0 increase
		891	it. Useful range is from -1 to 1 - the former results in a black, the
		892	latter in a white picture.
		893
		894	Due to idiosyncrasies in the underlying XRender extension, biases less
		895	than zero can be I<very> slow.
		896
		897	You can also try the experimental(!) C<muladd> operator.
571		898
572	=cut	899	=cut
573		900
574	sub contrast($$;$$;$) {	901	sub contrast($$;$$;$) {
575	my $img = pop;	902	my $img = pop;
576	my ($r, $g, $b, $a) = @_;	903	my ($r, $g, $b, $a) = @_;
577		904
578	($g, $b) = ($r, $r) if @_ < 4;	905	($g, $b) = ($r, $r) if @_ < 3;
579	$a = 1 if @_ < 5;	906	$a = 1 if @_ < 4;
580		907
581	$img = $img->clone;	908	$img = $img->clone;
582	$img->contrast ($r, $g, $b, $a);	909	$img->contrast ($r, $g, $b, $a);
583	$img	910	$img
584	}	911	}
585		912
586	sub brightness($$;$$;$) {	913	sub brightness($$;$$;$) {
587	my $img = pop;	914	my $img = pop;
588	my ($r, $g, $b, $a) = @_;	915	my ($r, $g, $b, $a) = @_;
589		916
590	($g, $b) = ($r, $r) if @_ < 4;	917	($g, $b) = ($r, $r) if @_ < 3;
591	$a = 1 if @_ < 5;	918	$a = 1 if @_ < 4;
592		919
593	$img = $img->clone;	920	$img = $img->clone;
594	$img->brightness ($r, $g, $b, $a);	921	$img->brightness ($r, $g, $b, $a);
595	$img	922	$img
		923	}
		924
		925	=item muladd $mul, $add, $img # EXPERIMENTAL
		926
		927	First multiplies the pixels by C<$mul>, then adds C<$add>. This can be used
		928	to implement brightness and contrast at the same time, with a wider value
		929	range than contrast and brightness operators.
		930
		931	Due to numerous bugs in XRender implementations, it can also introduce a
		932	number of visual artifacts.
		933
		934	Example: increase contrast by a factor of C<$c> without changing image
		935	brightness too much.
		936
		937	muladd $c, (1 - $c) * 0.5, $img
		938
		939	=cut
		940
		941	sub muladd($$$) {
		942	$_[2]->muladd ($_[0], $_[1])
596	}	943	}
597		944
598	=item blur $radius, $img	945	=item blur $radius, $img
599		946
600	=item blur $radius_horz, $radius_vert, $img	947	=item blur $radius_horz, $radius_vert, $img
…		…
612	sub blur($$;$) {	959	sub blur($$;$) {
613	my $img = pop;	960	my $img = pop;
614	$img->blur ($_[0], @_ >= 2 ? $_[1] : $_[0])	961	$img->blur ($_[0], @_ >= 2 ? $_[1] : $_[0])
615	}	962	}
616		963
617	=item rotate $new_width, $new_height, $center_x, $center_y, $degrees	964	=item focus_fade $img
618		965
619	Rotates the image by C<$degrees> degrees, counter-clockwise, around the	966	=item focus_fade $factor, $img
620	pointer at C<$center_x> and C<$center_y> (specified as percentage of image
621	width/height), generating a new image with width C<$new_width> and height
622	C<$new_height>.
623		967
624	#TODO# new width, height, maybe more operators?	968	=item focus_fade $factor, $color, $img
625		969
626	Example: rotate the image by 90 degrees	970	Fades the image by the given factor (and colour) when focus is lost (the
		971	same as the C<-fade>/C<-fadecolor> command line options, which also supply
		972	the default values for C<factor> and C<$color>. Unlike with C<-fade>, the
		973	C<$factor> is a real value, not a percentage value (that is, 0..1, not
		974	0..100).
627		975
628	=cut	976	Example: do the right thing when focus fading is requested.
629		977
630	sub rotate($$$$$$) {	978	focus_fade load "mybg.jpg";
		979
		980	=cut
		981
		982	sub focus_fade($;$$) {
631	my $img = pop;	983	my $img = pop;
632	$img->rotate (	984
633	$_[0],	985	return $img
634	$_[1],	986	if FOCUS;
635	$_[2] * $img->w * .01,	987
636	$_[3] * $img->h * .01,	988	my $fade = @_ >= 1 ? $_[0] : defined $self->resource ("fade") ? $self->resource ("fade") * 0.01 : 0;
637	$_[4] * (3.14159265 / 180),	989	my $color = @_ >= 2 ? $_[1] : $self->resource ("color+" . urxvt::Color_fade);
638	)	990
		991	$img = $img->tint ($color) if $color ne "rgb:00/00/00";
		992	$img = $img->muladd (1 - $fade, 0) if $fade;
		993
		994	$img
639	}	995	}
640		996
641	=back	997	=back
642		998
		999	=head2 OTHER STUFF
		1000
		1001	Anything that didn't fit any of the other categories, even after applying
		1002	force and closing our eyes.
		1003
		1004	=over 4
		1005
		1006	=item keep { ... }
		1007
		1008	This operator takes a code block as argument, that is, one or more
		1009	statements enclosed by braces.
		1010
		1011	The trick is that this code block is only evaluated when the outcome
		1012	changes - on other calls the C<keep> simply returns the image it computed
		1013	previously (yes, it should only be used with images). Or in other words,
		1014	C<keep> I<caches> the result of the code block so it doesn't need to be
		1015	computed again.
		1016
		1017	This can be extremely useful to avoid redoing slow operations - for
		1018	example, if your background expression takes the root background, blurs it
		1019	and then root-aligns it it would have to blur the root background on every
		1020	window move or resize.
		1021
		1022	Another example is C<load>, which can be quite slow.
		1023
		1024	In fact, urxvt itself encloses the whole expression in some kind of
		1025	C<keep> block so it only is reevaluated as required.
		1026
		1027	Putting the blur into a C<keep> block will make sure the blur is only done
		1028	once, while the C<rootalign> is still done each time the window moves.
		1029
		1030	rootalign keep { blur 10, root }
		1031
		1032	This leaves the question of how to force reevaluation of the block,
		1033	in case the root background changes: If expression inside the block
		1034	is sensitive to some event (root background changes, window geometry
		1035	changes), then it will be reevaluated automatically as needed.
		1036
		1037	=back
		1038
		1039	=head1 OLD BACKGROUND IMAGE SETTINGS
		1040
		1041	This extension also provides support for the old options/resources and
		1042	OSC sequences for setting a background image. These settings are
		1043	B<deprecated> and will be removed in future versions.
		1044
		1045	=head2 OPTIONS AND RESOURCES
		1046
		1047	=over 4
		1048
		1049	=item B<-pixmap> I<file[;oplist]>
		1050
		1051	=item B<backgroundPixmap:> I<file[;oplist]>
		1052
		1053	Use the specified image file as the window's background and also
		1054	optionally specify a colon separated list of operations to modify it.
		1055	Note that you may need to quote the C<;> character when using the
		1056	command line option, as C<;> is usually a metacharacter in shells.
		1057	Supported operations are:
		1058
		1059	=over 4
		1060
		1061	=item B<WxH+X+Y>
		1062
		1063	sets scale and position. B<"W" / "H"> specify the horizontal/vertical
		1064	scale (percent), and B<"X" / "Y"> locate the image centre (percent). A
		1065	scale of 0 disables scaling.
		1066
		1067	=item B<op=tile>
		1068
		1069	enables tiling
		1070
		1071	=item B<op=keep-aspect>
		1072
		1073	maintain the image aspect ratio when scaling
		1074
		1075	=item B<op=root-align>
		1076
		1077	use the position of the terminal window relative to the root window as
		1078	the image offset, simulating a root window background
		1079
		1080	=back
		1081
		1082	The default scale and position setting is C<100x100+50+50>.
		1083	Alternatively, a predefined set of templates can be used to achieve
		1084	the most common setups:
		1085
		1086	=over 4
		1087
		1088	=item B<style=tiled>
		1089
		1090	the image is tiled with no scaling. Equivalent to 0x0+0+0:op=tile
		1091
		1092	=item B<style=aspect-stretched>
		1093
		1094	the image is scaled to fill the whole window maintaining the aspect
		1095	ratio and centered. Equivalent to 100x100+50+50:op=keep-aspect
		1096
		1097	=item B<style=stretched>
		1098
		1099	the image is scaled to fill the whole window. Equivalent to 100x100
		1100
		1101	=item B<style=centered>
		1102
		1103	the image is centered with no scaling. Equivalent to 0x0+50+50
		1104
		1105	=item B<style=root-tiled>
		1106
		1107	the image is tiled with no scaling and using 'root' positioning.
		1108	Equivalent to 0x0:op=tile:op=root-align
		1109
		1110	=back
		1111
		1112	If multiple templates are specified the last one wins. Note that a
		1113	template overrides all the scale, position and operations settings.
		1114
		1115	If used in conjunction with pseudo-transparency, the specified image
		1116	will be blended over the transparent background using alpha-blending.
		1117
		1118	=item B<-tr>|B<+tr>
		1119
		1120	=item B<transparent:> I<boolean>
		1121
		1122	Turn on/off pseudo-transparency by using the root pixmap as background.
		1123
		1124	=item B<-tint> I<colour>
		1125
		1126	=item B<tintColor:> I<colour>
		1127
		1128	Tint the transparent background with the given colour. Note that a
		1129	black tint yields a completely black image while a white tint yields
		1130	the image unchanged.
		1131
		1132	=item B<-sh> I<number>
		1133
		1134	=item B<shading:> I<number>
		1135
		1136	Darken (0 .. 99) or lighten (101 .. 200) the transparent background.
		1137	A value of 100 means no shading.
		1138
		1139	=item B<-blr> I<HxV>
		1140
		1141	=item B<blurRadius:> I<HxV>
		1142
		1143	Apply gaussian blur with the specified radius to the transparent
		1144	background. If a single number is specified, the vertical and
		1145	horizontal radii are considered to be the same. Setting one of the
		1146	radii to 1 and the other to a large number creates interesting effects
		1147	on some backgrounds. The maximum radius value is 128. An horizontal or
		1148	vertical radius of 0 disables blurring.
		1149
		1150	=back
		1151
		1152	=head2 OSC sequences
		1153
		1154	This extension will react to the following OSC sequences. Note that
		1155	this extension will not be autoloaded when these are used currenmtly,
		1156	so to make urxvt recognize them, you have to enable the C<background>
		1157	extension. One way to achieve that is to use the C<--background-expr ''>
		1158	command line argument or by specifying an empty C<URxvt.background.expr:>>
		1159	resource.
		1160
		1161	=over 4
		1162
		1163	=item B<< C<ESC ] 705 ; Pt ST> >> Change transparent background tint colour to B<< C<Pt> >>.
		1164
		1165	=item B<< C<ESC ] 20 ; Pt ST> >> Change/Query background image
		1166	parameters: the value of B<< C<Pt> >> can be one of the following
		1167	commands:
		1168
		1169	=over 4
		1170
		1171	=item B<< C<?> >>
		1172
		1173	display scale and position in the title
		1174
		1175	=item B<< C<;WxH+X+Y> >>
		1176
		1177	change scale and/or position
		1178
		1179	=item B<< C<FILE;WxH+X+Y> >>
		1180
		1181	change background image
		1182
		1183	=back
		1184
		1185	=cut
		1186
		1187	sub keep(&) {
		1188	my $id = $_[0]+0;
		1189
		1190	local $frame = $self->{frame_cache}{$id} ||= [$frame];
		1191
		1192	unless ($frame->[FR_CACHE]) {
		1193	$frame->[FR_CACHE] = [ $_[0]() ];
		1194
		1195	my $self = $self;
		1196	my $frame = $frame;
		1197	Scalar::Util::weaken $frame;
		1198	$self->compile_frame ($frame, sub {
		1199	# clear this frame cache, also for all parents
		1200	for (my $frame = $frame; $frame; $frame = $frame->[0]) {
		1201	undef $frame->[FR_CACHE];
		1202	}
		1203
		1204	$self->recalculate;
		1205	});
		1206	};
		1207
		1208	# in scalar context we always return the first original result, which
		1209	# is not quite how perl works.
		1210	wantarray
		1211	? @{ $frame->[FR_CACHE] }
		1212	: $frame->[FR_CACHE][0]
		1213	}
		1214
		1215	# sub keep_clear() {
		1216	# delete $self->{frame_cache};
		1217	# }
		1218
		1219	=back
		1220
643	=cut	1221	=cut
644		1222
645	}	1223	}
646		1224
647	sub parse_expr {	1225	sub parse_expr {
648	my $expr = eval "sub {\npackage urxvt::bgdsl;\n#line 0 'background expression'\n$_[0]\n}";	1226	my ($expr) = @_;
		1227
		1228	# an empty expression is valid and represents the default background
		1229	if ($expr !~ /\S/) {
		1230	$expr = sub {
		1231	undef
		1232	};
		1233	} else {
		1234	$expr = eval
		1235	"sub {\n"
		1236	. "package urxvt::bgdsl;\n"
		1237	. "#line 0 'background expression'\n"
		1238	. "$expr\n"
		1239	. "}";
649	die if $@;	1240	die if $@;
		1241	}
		1242
650	$expr	1243	$expr
651	}	1244	}
652		1245
653	# compiles a parsed expression	1246	# compiles a parsed expression
654	sub set_expr {	1247	sub set_expr {
655	my ($self, $expr) = @_;	1248	my ($self, $expr) = @_;
656		1249
		1250	$self->{root} = []; # the outermost frame
657	$self->{expr} = $expr;	1251	$self->{expr} = $expr;
658	$self->recalculate;	1252	$self->recalculate;
		1253	}
		1254
		1255	# takes a hash of sensitivity indicators and installs watchers
		1256	sub compile_frame {
		1257	my ($self, $frame, $cb) = @_;
		1258
		1259	my $state = $frame->[urxvt::bgdsl::FR_STATE] ||= {};
		1260	my $again = $frame->[urxvt::bgdsl::FR_AGAIN];
		1261
		1262	# don't keep stuff alive
		1263	Scalar::Util::weaken $state;
		1264
		1265	if ($again->{nested}) {
		1266	$state->{nested} = 1;
		1267	} else {
		1268	delete $state->{nested};
		1269	}
		1270
		1271	if (my $interval = $again->{time}) {
		1272	$state->{time} = [$interval, urxvt::timer->new->after ($interval)->interval ($interval)]
		1273	if $state->{time}[0] != $interval;
		1274
		1275	# callback *might* have changed, although we could just rule that out
		1276	$state->{time}[1]->cb (sub {
		1277	++$state->{counter};
		1278	$cb->();
		1279	});
		1280	} else {
		1281	delete $state->{time};
		1282	}
		1283
		1284	if ($again->{position}) {
		1285	$state->{position} = $self->on (position_change => $cb);
		1286	} else {
		1287	delete $state->{position};
		1288	}
		1289
		1290	if ($again->{size}) {
		1291	$state->{size} = $self->on (size_change => $cb);
		1292	} else {
		1293	delete $state->{size};
		1294	}
		1295
		1296	if ($again->{rootpmap}) {
		1297	$state->{rootpmap} = $self->on (rootpmap_change => $cb);
		1298	} else {
		1299	delete $state->{rootpmap};
		1300	}
		1301
		1302	if ($again->{focus}) {
		1303	$state->{focus} = $self->on (focus_in => $cb, focus_out => $cb);
		1304	} else {
		1305	delete $state->{focus};
		1306	}
659	}	1307	}
660		1308
661	# evaluate the current bg expression	1309	# evaluate the current bg expression
662	sub recalculate {	1310	sub recalculate {
663	my ($arg_self) = @_;	1311	my ($arg_self) = @_;
…		…
671	return;	1319	return;
672	}	1320	}
673		1321
674	$arg_self->{next_refresh} = urxvt::NOW + $MIN_INTERVAL;	1322	$arg_self->{next_refresh} = urxvt::NOW + $MIN_INTERVAL;
675		1323
		1324	unless ($arg_self->has_render) {
		1325	warn "background extension needs RENDER extension 0.10 or higher, ignoring background-expr.\n";
		1326	return;
		1327	}
		1328
676	# set environment to evaluate user expression	1329	# set environment to evaluate user expression
677		1330
678	local $self = $arg_self;	1331	local $self = $arg_self;
679
680	local $HOME = $ENV{HOME};	1332	local $HOME = $ENV{HOME};
681	local $old = $self->{state};	1333	local $frame = $self->{root};
682	local $new = my $state = $self->{state} = {};
683		1334
684	($x, $y, $w, $h) =
685	$self->background_geometry ($self->{border});	1335	($x, $y, $w, $h) = $self->background_geometry ($self->{border});
		1336	$focus = $self->focus;
686		1337
687	# evaluate user expression	1338	# evaluate user expression
688		1339
689	my $img = eval { $self->{expr}->() };	1340	my @img = eval { $self->{expr}->() };
690	warn $@ if $@;#d#	1341	die $@ if $@;
		1342	die "background-expr did not return anything.\n" unless @img;
		1343
		1344	if ($img[0]) {
		1345	die "background-expr: expected image(s), got something else.\n"
691	die if !UNIVERSAL::isa $img, "urxvt::img";	1346	if grep { !UNIVERSAL::isa $_, "urxvt::img" } @img;
692		1347
693	$state->{size_sensitive} = 1	1348	my $img = urxvt::bgdsl::merge @img;
		1349
		1350	$frame->[FR_AGAIN]{size} = 1
694	if $img->repeat_mode != urxvt::RepeatNormal;	1351	if $img->repeat_mode != urxvt::RepeatNormal;
695		1352
696	# if the expression is sensitive to external events, prepare reevaluation then	1353	# if the expression is sensitive to external events, prepare reevaluation then
		1354	$self->compile_frame ($frame, sub { $arg_self->recalculate });
697		1355
698	my $repeat;	1356	# clear stuff we no longer need
699		1357
700	if (my $again = $state->{again}) {	1358	# unless (%{ $frame->[FR_STATE] }) {
701	$repeat = 1;	1359	# delete $self->{state};
702	my $self = $self;	1360	# delete $self->{expr};
703	$state->{timer} = $again == $old->{again}
704	? $old->{timer}
705	: urxvt::timer->new->after ($again)->interval ($again)->cb (sub {
706	++$self->{counter};
707	$self->recalculate
708	});
709	}	1361	# }
710		1362
711	if (delete $state->{position_sensitive}) {	1363	# set background pixmap
712	$repeat = 1;	1364
713	$self->enable (position_change => sub { $_[0]->recalculate });	1365	$self->set_background ($img, $self->{border});
714	} else {	1366	} else {
715	$self->disable ("position_change");	1367	$self->clr_background;
716	}	1368	}
717		1369
718	if (delete $state->{size_sensitive}) {
719	$repeat = 1;
720	$self->enable (size_change => sub { $_[0]->recalculate });
721	} else {
722	$self->disable ("size_change");
723	}
724
725	if (delete $state->{rootpmap_sensitive}) {
726	$repeat = 1;
727	$self->enable (rootpmap_change => sub { $_[0]->recalculate });
728	} else {
729	$self->disable ("rootpmap_change");
730	}
731
732	# clear stuff we no longer need
733
734	%$old = ();
735
736	unless ($repeat) {
737	delete $self->{state};
738	delete $self->{expr};
739	}
740
741	# set background pixmap
742
743	$self->set_background ($img, $self->{border});
744	$self->scr_recolour (0);	1370	$self->scr_recolor (0);
745	$self->want_refresh;	1371	$self->want_refresh;
746	}	1372	}
747		1373
		1374	sub old_bg_opts {
		1375	my ($self, $arg) = @_;
		1376
		1377	$arg or return;
		1378
		1379	my @str = split /;/, $arg;
		1380
		1381	return unless $str[0] or $self->{bg_opts}->{path};
		1382
		1383	my $bg_opts = $self->{bg_opts};
		1384
		1385	if ($str[0]) {
		1386	$bg_opts->{tile} = 0;
		1387	$bg_opts->{keep_aspect} = 0;
		1388	$bg_opts->{root_align} = 0;
		1389	$bg_opts->{h_scale} = $bg_opts->{v_scale} = 100;
		1390	$bg_opts->{h_align} = $bg_opts->{v_align} = 50;
		1391	$bg_opts->{path} = $str[0];
		1392	}
		1393
		1394	my @oplist = split /:/, $str[1];
		1395
		1396	for (@oplist) {
		1397	if (/style=tiled/i) {
		1398	$bg_opts->{tile} = 1;
		1399	$bg_opts->{keep_aspect} = 0;
		1400	$bg_opts->{root_align} = 0;
		1401	$bg_opts->{h_scale} = $bg_opts->{v_scale} = 0;
		1402	$bg_opts->{h_align} = $bg_opts->{v_align} = 0;
		1403	} elsif (/style=aspect-stretched/i) {
		1404	$bg_opts->{tile} = 0;
		1405	$bg_opts->{keep_aspect} = 1;
		1406	$bg_opts->{root_align} = 0;
		1407	$bg_opts->{h_scale} = $bg_opts->{v_scale} = 100;
		1408	$bg_opts->{h_align} = $bg_opts->{v_align} = 50;
		1409	} elsif (/style=stretched/i) {
		1410	$bg_opts->{tile} = 0;
		1411	$bg_opts->{keep_aspect} = 0;
		1412	$bg_opts->{root_align} = 0;
		1413	$bg_opts->{h_scale} = $bg_opts->{v_scale} = 100;
		1414	$bg_opts->{h_align} = $bg_opts->{v_align} = 50;
		1415	} elsif (/style=centered/i) {
		1416	$bg_opts->{tile} = 0;
		1417	$bg_opts->{keep_aspect} = 0;
		1418	$bg_opts->{root_align} = 0;
		1419	$bg_opts->{h_scale} = $bg_opts->{v_scale} = 0;
		1420	$bg_opts->{h_align} = $bg_opts->{v_align} = 50;
		1421	} elsif (/style=root-tiled/i) {
		1422	$bg_opts->{tile} = 1;
		1423	$bg_opts->{keep_aspect} = 0;
		1424	$bg_opts->{root_align} = 1;
		1425	$bg_opts->{h_scale} = $bg_opts->{v_scale} = 0;
		1426	$bg_opts->{h_align} = $bg_opts->{v_align} = 0;
		1427	} elsif (/op=tile/i) {
		1428	$bg_opts->{tile} = 1;
		1429	} elsif (/op=keep-aspect/i) {
		1430	$bg_opts->{keep_aspect} = 1;
		1431	} elsif (/op=root-align/i) {
		1432	$bg_opts->{root_align} = 1;
		1433	} elsif (/^ =? ([0-9]+)? (?:[xX] ([0-9]+))? ([+-][0-9]+)? ([+-][0-9]+)? $/x) {
		1434	my ($w, $h, $x, $y) = ($1, $2, $3, $4);
		1435
		1436	if ($str[0]) {
		1437	$w = $h unless defined $w;
		1438	$h = $w unless defined $h;
		1439	$y = $x unless defined $y;
		1440	}
		1441
		1442	$bg_opts->{h_scale} = $w if defined $w;
		1443	$bg_opts->{v_scale} = $h if defined $h;
		1444	$bg_opts->{h_align} = $x if defined $x;
		1445	$bg_opts->{v_align} = $y if defined $y;
		1446	}
		1447	}
		1448	}
		1449
		1450	# helper function, quote string as perl without allowing
		1451	# any code execution or other shenanigans. does not
		1452	# support binary NULs in string.
		1453	sub q0 {
		1454	(my $str = shift) =~ s/\x00//g; # make sure there really aren't any embedded NULs
		1455	"q\x00$str\x00"
		1456	}
		1457
		1458	sub old_bg_expr {
		1459	my ($self) = @_;
		1460
		1461	my $expr;
		1462
		1463	my $bg_opts = $self->{bg_opts};
		1464
		1465	if ($bg_opts->{root} =~ /^\s*(?:true|yes|on|1)\s*$/i) {
		1466	$expr .= "tile (";
		1467
		1468	my $shade = $bg_opts->{shade};
		1469
		1470	if ($shade) {
		1471	$shade = List::Util::min $shade, 200;
		1472	$shade = List::Util::max $shade, -100;
		1473	$shade = 200 - (100 + $shade) if $shade < 0;
		1474
		1475	$shade = $shade * 0.01 - 1;
		1476	$expr .= "shade $shade, ";
		1477	}
		1478
		1479	my $tint = $bg_opts->{tint};
		1480
		1481	if ($tint) {
		1482	$tint = q0 $tint;
		1483	$expr .= "tint $tint,";
		1484	}
		1485
		1486	my $blur = $bg_opts->{blur};
		1487
		1488	if ($blur and $blur =~ /^ =? ([0-9]+)? (?:[xX] ([0-9]+))? $/x) {
		1489	my $hr = defined $1 ? $1 : 1;
		1490	my $vr = defined $2 ? $2 : $hr;
		1491
		1492	if ($hr != 0 and $vr != 0) {
		1493	$expr .= "blur $hr, $vr, ";
		1494	}
		1495	}
		1496
		1497	$expr .= "rootalign root)";
		1498	}
		1499
		1500	if ($bg_opts->{path}) {
		1501	my $file_expr;
		1502	my $h_scale = $bg_opts->{h_scale} * 0.01;
		1503	my $v_scale = $bg_opts->{v_scale} * 0.01;
		1504	my $h_align = $bg_opts->{h_align} * 0.01;
		1505	my $v_align = $bg_opts->{v_align} * 0.01;
		1506
		1507	if (!$bg_opts->{tile}) {
		1508	$file_expr .= "pad (";
		1509	} else {
		1510	$file_expr .= "tile (";
		1511	}
		1512
		1513	if ($bg_opts->{root_align}) {
		1514	$file_expr .= "rootalign ";
		1515	} else {
		1516	$file_expr .= "align $h_align, $v_align, ";
		1517	}
		1518
		1519	if ($h_scale != 0 and $v_scale != 0) {
		1520	my $op = $bg_opts->{keep_aspect} ? "fit" : "resize";
		1521	$file_expr .= "$op TW * $h_scale, TH * $v_scale, ";
		1522	}
		1523
		1524	my $path = q0 $bg_opts->{path};
		1525
		1526	$file_expr .= "keep { load $path })";
		1527
		1528	if ($expr) {
		1529	$expr .= ", tint (\"[50]white\", $file_expr)";
		1530	} else {
		1531	$expr = $file_expr;
		1532	}
		1533	}
		1534
		1535	$expr
		1536	}
		1537
		1538	sub on_osc_seq {
		1539	my ($self, $op, $arg) = @_;
		1540
		1541	$self->{bg_opts} or return;
		1542
		1543	$op =~ /^(?:20|705)$/ or return;
		1544
		1545	if ($op eq "20") {
		1546	if ($arg eq "?") {
		1547	my $h_scale = $self->{bg_opts}->{h_scale};
		1548	my $v_scale = $self->{bg_opts}->{v_scale};
		1549	my $h_align = $self->{bg_opts}->{h_align};
		1550	my $v_align = $self->{bg_opts}->{v_align};
		1551	$self->cmd_parse ("\033]2;[${h_scale}x${v_scale}+${h_align}+${v_align}]\007");
		1552	} else {
		1553	$self->old_bg_opts ($arg);
		1554	my $expr = $self->old_bg_expr;
		1555	$self->set_expr (parse_expr $expr) if $expr;
		1556	}
		1557	} elsif ($op eq "705") {
		1558	$self->{bg_opts}->{tint} = $arg;
		1559	my $expr = $self->old_bg_expr;
		1560	$self->set_expr (parse_expr $expr) if $expr;
		1561	}
		1562
		1563	1
		1564	}
		1565
		1566	sub find_resource {
		1567	my ($self, $res, $opt) = @_;
		1568
		1569	my $v = $self->x_resource ($opt);
		1570	$v = $self->x_resource ($res) unless defined $v;
		1571
		1572	$v
		1573	}
		1574
748	sub on_start {	1575	sub on_start {
749	my ($self) = @_;	1576	my ($self) = @_;
750		1577
751	my $expr = $self->x_resource ("background.expr")	1578	my $expr = $self->x_resource ("%.expr");
752	or return;	1579
		1580	if (!$expr) {
		1581	$self->{bg_opts} = { h_scale => 100, v_scale => 100,
		1582	h_align => 50, v_align => 50 };
		1583
		1584	$self->{bg_opts}{shade} = $self->find_resource ("shading", "sh");
		1585	$self->{bg_opts}{tint} = $self->find_resource ("tintColor", "tint");
		1586	$self->{bg_opts}{blur} = $self->find_resource ("blurRadius", "blr");
		1587	$self->{bg_opts}{root} = $self->find_resource ("transparent", "tr");
		1588
		1589	$self->old_bg_opts ($self->find_resource ("backgroundPixmap", "pixmap"));
		1590	$expr = $self->old_bg_expr;
		1591	}
753		1592
754	$self->set_expr (parse_expr $expr);	1593	$self->set_expr (parse_expr $expr);
755	$self->{border} = $self->x_resource_boolean ("background.border");	1594	$self->{border} = $self->x_resource_boolean ("%.border");
		1595
		1596	$MIN_INTERVAL = $self->x_resource ("%.interval");
756		1597
757	()	1598	()
758	}	1599	}
759		1600

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