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Revision 1.42 by root, Sun Jun 10 10:42:19 2012 UTC vs.
Revision 1.106 by root, Tue Nov 29 04:44:27 2022 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
		16	#:META:OSC:20:change/query background image
		17	#:META:OSC:705:change transparent background tint colour
7		18
8	=head1 NAME	19	=head1 NAME
9		20
10	background - manage terminal background	21	background - manage terminal background
11		22
12	=head1 SYNOPSIS	23	=head1 SYNOPSIS
13		24
14	urxvt --background-expr 'background expression'	25	urxvt --background-expr 'background expression'
15	--background-border	26	--background-border
		27	--background-interval seconds
		28
		29	=head1 QUICK AND DIRTY CHEAT SHEET
		30
		31	Load a random jpeg image and tile the background with it without scaling
		32	or anything else:
		33
		34	load "/path/to/img.jpg"
		35
		36	The same, but use mirroring/reflection instead of tiling:
		37
		38	mirror load "/path/to/img.jpg"
		39
		40	Load an image and scale it to exactly fill the terminal window:
		41
		42	scale keep { load "/path/to/img.jpg" }
		43
		44	Implement pseudo-transparency by using a suitably-aligned root pixmap
		45	as window background:
		46
		47	rootalign root
		48
		49	Likewise, but keep a blurred copy:
		50
		51	rootalign keep { blur 10, root }
16		52
17	=head1 DESCRIPTION	53	=head1 DESCRIPTION
18		54
19	This extension manages the terminal background by creating a picture that	55	This extension manages the terminal background by creating a picture that
20	is behind the text, replacing the normal background colour.	56	is behind the text, replacing the normal background colour.
21		57
22	It does so by evaluating a Perl expression that I<calculates> the image on	58	It does so by evaluating a Perl expression that I<calculates> the image on
23	the fly, for example, by grabbing the root background or loading a file.	59	the fly, for example, by grabbing the root background or loading a file.
24		60
25	While the full power of Perl is available, the operators have been design	61	While the full power of Perl is available, the operators have been
26	to be as simple as possible.	62	designed to be as simple as possible.
27		63
28	For example, to load an image and scale it to the window size, you would	64	For example, to load an image and scale it to the window size, you would
29	use:	65	use:
30		66
31	urxvt --background-expr 'scale load "/path/to/mybg.png"'	67	urxvt --background-expr 'scale keep { load "/path/to/mybg.png" }'
32		68
33	Or specified as a X resource:	69	Or specified as a X resource:
34		70
35	URxvt.background-expr: scale load "/path/to/mybg.png"	71	URxvt.background.expr: scale keep { load "/path/to/mybg.png" }
36		72
37	=head1 THEORY OF OPERATION	73	=head1 THEORY OF OPERATION
38		74
39	At startup, just before the window is mapped for the first time, the	75	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	76	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	89	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	90	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	91	pixmap is replaced by another one the root background changes; or when the
56	timer elapses), then the expression will be evaluated again.	92	timer elapses), then the expression will be evaluated again.
57		93
58	For example, an expression such as C<scale load "$HOME/mybg.png"> scales the	94	For example, an expression such as C<scale keep { load "$HOME/mybg.png"
59	image to the window size, so it relies on the window size and will	95	}> 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	96	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	97	example. That ensures that the picture always fills the terminal, even
62	after it's size changes.	98	after its size changes.
63		99
64	=head2 EXPRESSIONS	100	=head2 EXPRESSIONS
65		101
66	Expressions are normal Perl expressions, in fact, they are Perl blocks -	102	Expressions are normal Perl expressions, in fact, they are Perl blocks -
67	which means you could use multiple lines and statements:	103	which means you could use multiple lines and statements:
68		104
		105	scale keep {
69	again 3600;	106	again 3600;
70	if (localtime now)[6]) {	107	if (localtime now)[6]) {
71	return scale load "$HOME/weekday.png";	108	return load "$HOME/weekday.png";
72	} else {	109	} else {
73	return scale load "$HOME/sunday.png";	110	return load "$HOME/sunday.png";
		111	}
74	}	112	}
75		113
76	This expression gets evaluated once per hour. It will set F<sunday.png> as	114	This inner expression is evaluated once per hour (and whenever the
		115	terminal window is resized). It sets F<sunday.png> as background on
77	background on Sundays, and F<weekday.png> on all other days.	116	Sundays, and F<weekday.png> on all other days.
78		117
79	Fortunately, we expect that most expressions will be much simpler, with	118	Fortunately, we expect that most expressions will be much simpler, with
80	little Perl knowledge needed.	119	little Perl knowledge needed.
81		120
82	Basically, you always start with a function that "generates" an image	121	Basically, you always start with a function that "generates" an image
…		…
99	its result becomes the argument to the C<scale> function.	138	its result becomes the argument to the C<scale> function.
100		139
101	Many operators also allow some parameters preceding the input image	140	Many operators also allow some parameters preceding the input image
102	that modify its behaviour. For example, C<scale> without any additional	141	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	142	arguments scales the image to size of the terminal window. If you specify
104	an additional argument, it uses it as a percentage:	143	an additional argument, it uses it as a scale factor (multiply by 100 to
		144	get a percentage):
105		145
106	scale 200, load "$HOME/mypic.png"	146	scale 2, load "$HOME/mypic.png"
107		147
108	This enlarges the image by a factor of 2 (200%). As you can see, C<scale>	148	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	149	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	150	C<load> only has one argument. Arguments are separated from each other by
111	commas.	151	commas.
112		152
113	Scale also accepts two arguments, which are then separate factors for both	153	Scale also accepts two arguments, which are then separate factors for both
114	horizontal and vertical dimensions. For example, this halves the image	154	horizontal and vertical dimensions. For example, this halves the image
115	width and doubles the image height:	155	width and doubles the image height:
116		156
117	scale 50, 200, load "$HOME/mypic.png"	157	scale 0.5, 2, load "$HOME/mypic.png"
118		158
119	Other effects than scalign are also readily available, for exmaple, you can	159	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:	160	because each time the terminal is resized, it loads the PNG image again
		161	and scales it. Scaling is usually fast (and unavoidable), but loading the
		162	image can be quite time consuming. This is where C<keep> comes in handy:
121		163
		164	scale 0.5, 2, keep { load "$HOME/mypic.png" }
		165
		166	The C<keep> operator executes all the statements inside the braces only
		167	once, or when it thinks the outcome might change. In other cases it
		168	returns the last value computed by the brace block.
		169
		170	This means that the C<load> is only executed once, which makes it much
		171	faster, but also means that more memory is being used, because the loaded
		172	image must be kept in memory at all times. In this expression, the
		173	trade-off is likely worth it.
		174
		175	But back to effects: Other effects than scaling are also readily
		176	available, for example, you can tile the image to fill the whole window,
		177	instead of resizing it:
		178
122	tile load "$HOME/mypic.png"	179	tile keep { load "$HOME/mypic.png" }
123		180
124	In fact, images returned by C<load> are in C<tile> mode by default, so the C<tile> operator	181	In fact, images returned by C<load> are in C<tile> mode by default, so the
125	is kind of superfluous.	182	C<tile> operator is kind of superfluous.
126		183
127	Another common effect is to mirror the image, so that the same edges touch:	184	Another common effect is to mirror the image, so that the same edges
		185	touch:
128		186
129	mirror load "$HOME/mypic.png"	187	mirror keep { load "$HOME/mypic.png" }
130		188
131	This is also a typical background expression:	189	Another common background expression is:
132		190
133	rootalign root	191	rootalign root
134		192
135	It first takes a snapshot of the screen background image, and then	193	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	194	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	195	left corner of the terminal window)- the result is pseudo-transparency:
138	moved around.	196	the image seems to be static while the window is moved around.
139		197
140	=head2 CYCLES AND CACHING	198	=head2 COLOUR SPECIFICATIONS
141		199
142	As has been mentioned before, the expression might be evaluated multiple	200	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	201	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		202
146	For example, the C<load> operator keeps a copy of the image. If it is	203	"red" # named colour
147	asked to load the same image on the next cycle it will not load it again,	204	"#f00" # simple rgb
148	but return the cached copy.	205	"[50]red" # red with 50% alpha
		206	"TekHVC:300/50/50" # anything goes
149		207
150	This only works for one cycle though, so as long as you load the same	208	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		209
154	This allows you to either speed things up by keeping multiple images in	210	[0.5] # 50% gray, 100% alpha
155	memory, or comserve memory by loading images more often.	211	[0.5, 0, 0] # dark red, no green or blur, 100% alpha
		212	[0.5, 0, 0, 0.7] # same with explicit 70% alpha
156		213
157	For example, you can keep two images in memory and use a random one like	214	=head2 CACHING AND SENSITIVITY
158	this:
159		215
160	my $img1 = load "img1.png";	216	Since some operations (such as C<load> and C<blur>) can take a long time,
161	my $img2 = load "img2.png";	217	caching results can be very important for a smooth operation. Caching can
162	(0.5 > rand) ? $img1 : $img2	218	also be useful to reduce memory usage, though, for example, when an image
		219	is cached by C<load>, it could be shared by multiple terminal windows
		220	running inside urxvtd.
163		221
164	Since both images are "loaded" every time the expression is evaluated,	222	=head3 C<keep { ... }> caching
165	they are always kept in memory. Contrast this version:
166		223
167	my $path1 = "img1.png";	224	The most important way to cache expensive operations is to use C<keep {
168	my $path2 = "img2.png";	225	... }>. The C<keep> operator takes a block of multiple statements enclosed
169	load ((0.5 > rand) ? $path1 : $path2)	226	by C<{}> and keeps the return value in memory.
170		227
171	Here, a path is selected randomly, and load is only called for one image,	228	An expression can be "sensitive" to various external events, such as
172	so keeps only one image in memory. If, on the next evaluation, luck	229	scaling or moving the window, root background changes and timers. Simply
173	decides to use the other path, then it will have to load that image again.	230	using an expression (such as C<scale> without parameters) that depends on
		231	certain changing values (called "variables"), or using those variables
		232	directly, will make an expression sensitive to these events - for example,
		233	using C<scale> or C<TW> will make the expression sensitive to the terminal
		234	size, and thus to resizing events.
		235
		236	When such an event happens, C<keep> will automatically trigger a
		237	reevaluation of the whole expression with the new value of the expression.
		238
		239	C<keep> is most useful for expensive operations, such as C<blur>:
		240
		241	rootalign keep { blur 20, root }
		242
		243	This makes a blurred copy of the root background once, and on subsequent
		244	calls, just root-aligns it. Since C<blur> is usually quite slow and
		245	C<rootalign> is quite fast, this trades extra memory (for the cached
		246	blurred pixmap) with speed (blur only needs to be redone when root
		247	changes).
		248
		249	=head3 C<load> caching
		250
		251	The C<load> operator itself does not keep images in memory, but as long as
		252	the image is still in memory, C<load> will use the in-memory image instead
		253	of loading it freshly from disk.
		254
		255	That means that this expression:
		256
		257	keep { load "$HOME/path..." }
		258
		259	Not only caches the image in memory, other terminal instances that try to
		260	C<load> it can reuse that in-memory copy.
174		261
175	=head1 REFERENCE	262	=head1 REFERENCE
176		263
177	=head2 COMMAND LINE SWITCHES	264	=head2 COMMAND LINE SWITCHES
178		265
179	=over 4	266	=over
180		267
181	=item --background-expr perl-expression	268	=item --background-expr perl-expression
182		269
183	Specifies the Perl expression to evaluate.	270	Specifies the Perl expression to evaluate.
184		271
…		…
188	overwriting borders and any other areas, such as the scrollbar.	275	overwriting borders and any other areas, such as the scrollbar.
189		276
190	Specifying this flag changes the behaviour, so that the image only	277	Specifying this flag changes the behaviour, so that the image only
191	replaces the background of the character area.	278	replaces the background of the character area.
192		279
		280	=item --background-interval seconds
		281
		282	Since some operations in the underlying XRender extension can effectively
		283	freeze your X-server for prolonged time, this extension enforces a minimum
		284	time between updates, which is normally about 0.1 seconds.
		285
		286	If you want to do updates more often, you can decrease this safety
		287	interval with this switch.
		288
193	=back	289	=back
194		290
195	=cut	291	=cut
196		292
		293	our %_IMG_CACHE;
197	our $HOME;	294	our $HOME;
198	our ($self, $old, $new);	295	our ($self, $frame);
199	our ($x, $y, $w, $h);	296	our ($x, $y, $w, $h, $focus);
200		297
201	# enforce at least this interval between updates	298	# enforce at least this interval between updates
202	our $MIN_INTERVAL = 1/100;	299	our $MIN_INTERVAL = 6/59.951;
203		300
204	{	301	{
205	package urxvt::bgdsl; # background language	302	package urxvt::bgdsl; # background language
		303
		304	sub FR_PARENT() { 0 } # parent frame, if any - must be #0
		305	sub FR_CACHE () { 1 } # cached values
		306	sub FR_AGAIN () { 2 } # what this expr is sensitive to
		307	sub FR_STATE () { 3 } # watchers etc.
		308
		309	use List::Util qw(min max sum shuffle);
206		310
207	=head2 PROVIDERS/GENERATORS	311	=head2 PROVIDERS/GENERATORS
208		312
209	These functions provide an image, by loading it from disk, grabbing it	313	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	314	from the root screen or by simply generating it. They are used as starting
211	points to get an image you can play with.	315	points to get an image you can play with.
212		316
213	=over 4	317	=over
214		318
215	=item load $path	319	=item load $path
216		320
217	Loads the image at the given C<$path>. The image is set to plane tiling	321	Loads the image at the given C<$path>. The image is set to plane tiling
218	mode.	322	mode.
219		323
220	Loaded images will be cached for one cycle.	324	If the image is already in memory (e.g. because another terminal instance
		325	uses it), then the in-memory copy is returned instead.
221		326
		327	=item load_uc $path
		328
		329	Load uncached - same as load, but does not cache the image, which means it
		330	is I<always> loaded from the filesystem again, even if another copy of it
		331	is in memory at the time.
		332
222	=cut	333	=cut
		334
		335	sub load_uc($) {
		336	$self->new_img_from_file ($_[0])
		337	}
223		338
224	sub load($) {	339	sub load($) {
225	my ($path) = @_;	340	my ($path) = @_;
226		341
227	$new->{load}{$path} = $old->{load}{$path} || $self->new_img_from_file ($path);	342	$_IMG_CACHE{$path} || do {
		343	my $img = load_uc $path;
		344	Scalar::Util::weaken ($_IMG_CACHE{$path} = $img);
		345	$img
		346	}
228	}	347	}
229		348
230	=item root	349	=item root
231		350
232	Returns the root window pixmap, that is, hopefully, the background image	351	Returns the root window pixmap, that is, hopefully, the background image
233	of your screen. The image is set to extend mode.	352	of your screen.
234		353
235	This function makes your expression root sensitive, that means it will be	354	This function makes your expression root sensitive, that means it will be
236	reevaluated when the bg image changes.	355	reevaluated when the bg image changes.
237		356
238	=cut	357	=cut
239		358
240	sub root() {	359	sub root() {
241	$new->{rootpmap_sensitive} = 1;	360	$frame->[FR_AGAIN]{rootpmap} = 1;
242	die "root op not supported, exg, we need you";	361	$self->new_img_from_root
243	}	362	}
244		363
245	=item solid $colour	364	=item solid $colour
246		365
247	=item solid $width, $height, $colour	366	=item solid $width, $height, $colour
…		…
255	=cut	374	=cut
256		375
257	sub solid($;$$) {	376	sub solid($;$$) {
258	my $colour = pop;	377	my $colour = pop;
259		378
260	my $img = $self->new_img (urxvt::PictStandardARGB32, $_[0] || 1, $_[1] || 1);	379	my $img = $self->new_img (urxvt::PictStandardARGB32, 0, 0, $_[0] || 1, $_[1] || 1);
261	$img->fill ($colour);	380	$img->fill ($colour);
262	$img	381	$img
263	}	382	}
264		383
265	=back	384	=item clone $img
266		385
267	=head2 VARIABLES	386	Returns an exact copy of the image. This is useful if you want to have
		387	multiple copies of the same image to apply different effects to.
268		388
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	389	=cut
311		390
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} = $_[0];
345	}
346
347	sub counter($) {	391	sub clone($) {
348	$new->{again} = $_[0];	392	$_[0]->clone
349	$self->{counter} + 0	393	}
		394
		395	=item merge $img ...
		396
		397	Takes any number of images and merges them together, creating a single
		398	image containing them all. The tiling mode of the first image is used as
		399	the tiling mode of the resulting image.
		400
		401	This function is called automatically when an expression returns multiple
		402	images.
		403
		404	=cut
		405
		406	sub merge(@) {
		407	return $_[0] unless $#_;
		408
		409	# rather annoyingly clumsy, but optimisation is for another time
		410
		411	my $x0 = +1e9;
		412	my $y0 = +1e9;
		413	my $x1 = -1e9;
		414	my $y1 = -1e9;
		415
		416	for (@_) {
		417	my ($x, $y, $w, $h) = $_->geometry;
		418
		419	$x0 = $x if $x0 > $x;
		420	$y0 = $y if $y0 > $y;
		421
		422	$x += $w;
		423	$y += $h;
		424
		425	$x1 = $x if $x1 < $x;
		426	$y1 = $y if $y1 < $y;
		427	}
		428
		429	my $base = $self->new_img (urxvt::PictStandardARGB32, $x0, $y0, $x1 - $x0, $y1 - $y0);
		430	$base->repeat_mode ($_[0]->repeat_mode);
		431	$base->fill ([0, 0, 0, 0]);
		432
		433	$base->draw ($_)
		434	for @_;
		435
		436	$base
350	}	437	}
351		438
352	=back	439	=back
353		440
354	=head2 TILING MODES	441	=head2 TILING MODES
355		442
356	The following operators modify the tiling mode of an image, that is, the	443	The following operators modify the tiling mode of an image, that is, the
357	way that pixels outside the image area are painted when the image is used.	444	way that pixels outside the image area are painted when the image is used.
358		445
359	=over 4	446	=over
360		447
361	=item tile $img	448	=item tile $img
362		449
363	Tiles the whole plane with the image and returns this new image - or in	450	Tiles the whole plane with the image and returns this new image - or in
364	other words, it returns a copy of the image in plane tiling mode.	451	other words, it returns a copy of the image in plane tiling mode.
…		…
387	become transparent. This mode is most useful when you want to place an	474	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	475	image over another image or the background colour while leaving all
389	background pixels outside the image unchanged.	476	background pixels outside the image unchanged.
390		477
391	Example: load an image and display it in the upper left corner. The rest	478	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	479	of the space is left "empty" (transparent or whatever your compositor does
393	in alpha mode, else background colour).	480	in alpha mode, else background colour).
394		481
395	pad load "mybg.png"	482	pad load "mybg.png"
396		483
397	=item extend $img	484	=item extend $img
398		485
399	Extends the image over the whole plane, using the closest pixel in the	486	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	487	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	488	filtering operations and want the pixels outside the image to have the
402	same values as the pixels near the edge.	489	same values as the pixels near the edge.
403		490
404	Example: just for curiosity, how does this pixel extension stuff work?	491	Example: just for curiosity, how does this pixel extension stuff work?
405		492
…		…
431	$img	518	$img
432	}	519	}
433		520
434	=back	521	=back
435		522
436	=head2 PIXEL OPERATORS	523	=head2 VARIABLE VALUES
437		524
438	The following operators modify the image pixels in various ways.	525	The following functions provide variable data such as the terminal window
		526	dimensions. They are not (Perl-) variables, they just return stuff that
		527	varies. Most of them make your expression sensitive to some events, for
		528	example using C<TW> (terminal width) means your expression is evaluated
		529	again when the terminal is resized.
439		530
440	=over 4	531	=over
441		532
442	=item clone $img	533	=item TX
443		534
444	Returns an exact copy of the image.	535	=item TY
445		536
446	=cut	537	Return the X and Y coordinates of the terminal window (the terminal
		538	window is the full window by default, and the character area only when in
		539	border-respect mode).
447		540
		541	Using these functions makes your expression sensitive to window moves.
		542
		543	These functions are mainly useful to align images to the root window.
		544
		545	Example: load an image and align it so it looks as if anchored to the
		546	background (that's exactly what C<rootalign> does btw.):
		547
		548	move -TX, -TY, keep { load "mybg.png" }
		549
		550	=item TW
		551
		552	=item TH
		553
		554	Return the width (C<TW>) and height (C<TH>) of the terminal window (the
		555	terminal window is the full window by default, and the character area only
		556	when in border-respect mode).
		557
		558	Using these functions makes your expression sensitive to window resizes.
		559
		560	These functions are mainly useful to scale images, or to clip images to
		561	the window size to conserve memory.
		562
		563	Example: take the screen background, clip it to the window size, blur it a
		564	bit, align it to the window position and use it as background.
		565
		566	clip move -TX, -TY, keep { blur 5, root }
		567
		568	=item FOCUS
		569
		570	Returns a boolean indicating whether the terminal window has keyboard
		571	focus, in which case it returns true.
		572
		573	Using this function makes your expression sensitive to focus changes.
		574
		575	A common use case is to fade the background image when the terminal loses
		576	focus, often together with the C<-fade> command line option. In fact,
		577	there is a special function for just that use case: C<focus_fade>.
		578
		579	Example: use two entirely different background images, depending on
		580	whether the window has focus.
		581
		582	FOCUS ? keep { load "has_focus.jpg" } : keep { load "no_focus.jpg" }
		583
		584	=cut
		585
		586	sub TX () { $frame->[FR_AGAIN]{position} = 1; $x }
		587	sub TY () { $frame->[FR_AGAIN]{position} = 1; $y }
		588	sub TW () { $frame->[FR_AGAIN]{size} = 1; $w }
		589	sub TH () { $frame->[FR_AGAIN]{size} = 1; $h }
		590	sub FOCUS() { $frame->[FR_AGAIN]{focus} = 1; $focus }
		591
		592	=item now
		593
		594	Returns the current time as (fractional) seconds since the epoch.
		595
		596	Using this expression does I<not> make your expression sensitive to time,
		597	but the next two functions do.
		598
		599	=item again $seconds
		600
		601	When this function is used the expression will be reevaluated again in
		602	C<$seconds> seconds.
		603
		604	Example: load some image and rotate it according to the time of day (as if it were
		605	the hour pointer of a clock). Update this image every minute.
		606
		607	again 60;
		608	rotate 50, 50, (now % 86400) * -72 / 8640, scale keep { load "myclock.png" }
		609
		610	=item counter $seconds
		611
		612	Like C<again>, but also returns an increasing counter value, starting at
		613	0, which might be useful for some simple animation effects.
		614
		615	=cut
		616
		617	sub now() { urxvt::NOW }
		618
		619	sub again($) {
		620	$frame->[FR_AGAIN]{time} = $_[0];
		621	}
		622
448	sub clone($) {	623	sub counter($) {
449	$_[0]->clone	624	$frame->[FR_AGAIN]{time} = $_[0];
		625	$frame->[FR_STATE]{counter} + 0
450	}	626	}
		627
		628	=back
		629
		630	=head2 SHAPE CHANGING OPERATORS
		631
		632	The following operators modify the shape, size or position of the image.
		633
		634	=over
451		635
452	=item clip $img	636	=item clip $img
453		637
454	=item clip $width, $height, $img	638	=item clip $width, $height, $img
455		639
…		…
458	Clips an image to the given rectangle. If the rectangle is outside the	642	Clips an image to the given rectangle. If the rectangle is outside the
459	image area (e.g. when C<$x> or C<$y> are negative) or the rectangle is	643	image area (e.g. when C<$x> or C<$y> are negative) or the rectangle is
460	larger than the image, then the tiling mode defines how the extra pixels	644	larger than the image, then the tiling mode defines how the extra pixels
461	will be filled.	645	will be filled.
462		646
463	If C<$x> an C<$y> are missing, then C<0> is assumed for both.	647	If C<$x> and C<$y> are missing, then C<0> is assumed for both.
464		648
465	If C<$width> and C<$height> are missing, then the window size will be	649	If C<$width> and C<$height> are missing, then the window size will be
466	assumed.	650	assumed.
467		651
468	Example: load an image, blur it, and clip it to the window size to save	652	Example: load an image, blur it, and clip it to the window size to save
469	memory.	653	memory.
470		654
471	clip blur 10, load "mybg.png"	655	clip keep { blur 10, load "mybg.png" }
472		656
473	=cut	657	=cut
474		658
475	sub clip($;$$;$$) {	659	sub clip($;$$;$$) {
476	my $img = pop;	660	my $img = pop;
…		…
479	$img->sub_rect ($_[0], $_[1], $w, $h)	663	$img->sub_rect ($_[0], $_[1], $w, $h)
480	}	664	}
481		665
482	=item scale $img	666	=item scale $img
483		667
484	=item scale $size_percent, $img	668	=item scale $size_factor, $img
485		669
486	=item scale $width_percent, $height_percent, $img	670	=item scale $width_factor, $height_factor, $img
487		671
488	Scales the image by the given percentages in horizontal	672	Scales the image by the given factors in horizontal
489	(C<$width_percent>) and vertical (C<$height_percent>) direction.	673	(C<$width>) and vertical (C<$height>) direction.
490		674
491	If only one percentage is give, it is used for both directions.	675	If only one factor is given, it is used for both directions.
492		676
493	If no percentages are given, scales the image to the window size without	677	If no factors are given, scales the image to the window size without
494	keeping aspect.	678	keeping aspect.
495		679
496	=item resize $width, $height, $img	680	=item resize $width, $height, $img
497		681
498	Resizes the image to exactly C<$width> times C<$height> pixels.	682	Resizes the image to exactly C<$width> times C<$height> pixels.
499		683
500	=cut	684	=item fit $img
501		685
502	#TODO: maximise, maximise_fill?	686	=item fit $width, $height, $img
		687
		688	Fits the image into the given C<$width> and C<$height> without changing
		689	aspect, or the terminal size. That means it will be shrunk or grown until
		690	the whole image fits into the given area, possibly leaving borders.
		691
		692	=item cover $img
		693
		694	=item cover $width, $height, $img
		695
		696	Similar to C<fit>, but shrinks or grows until all of the area is covered
		697	by the image, so instead of potentially leaving borders, it will cut off
		698	image data that doesn't fit.
		699
		700	=cut
503		701
504	sub scale($;$;$) {	702	sub scale($;$;$) {
505	my $img = pop;	703	my $img = pop;
506		704
507	@_ == 2 ? $img->scale ($_[0] * $img->w * 0.01, $_[1] * $img->h * 0.01)	705	@_ == 2 ? $img->scale ($_[0] * $img->w, $_[1] * $img->h)
508	: @_ ? $img->scale ($_[0] * $img->w * 0.01, $_[0] * $img->h * 0.01)	706	: @_ ? $img->scale ($_[0] * $img->w, $_[0] * $img->h)
509	: $img->scale (TW, TH)	707	: $img->scale (TW, TH)
510	}	708	}
511		709
512	sub resize($$$) {	710	sub resize($$$) {
513	my $img = pop;	711	my $img = pop;
514	$img->scale ($_[0], $_[1])	712	$img->scale ($_[0], $_[1])
515	}	713	}
516		714
		715	sub fit($;$$) {
		716	my $img = pop;
		717	my $w = ($_[0] || TW) / $img->w;
		718	my $h = ($_[1] || TH) / $img->h;
		719	scale +(min $w, $h), $img
		720	}
		721
		722	sub cover($;$$) {
		723	my $img = pop;
		724	my $w = ($_[0] || TW) / $img->w;
		725	my $h = ($_[1] || TH) / $img->h;
		726	scale +(max $w, $h), $img
		727	}
		728
517	=item move $dx, $dy, $img	729	=item move $dx, $dy, $img
518		730
519	Moves the image by C<$dx> pixels in the horizontal, and C<$dy> pixels in	731	Moves the image by C<$dx> pixels in the horizontal, and C<$dy> pixels in
520	the vertical.	732	the vertical.
521		733
522	Example: move the image right by 20 pixels and down by 30.	734	Example: move the image right by 20 pixels and down by 30.
523		735
524	move 20, 30, ...	736	move 20, 30, ...
		737
		738	=item align $xalign, $yalign, $img
		739
		740	Aligns the image according to a factor - C<0> means the image is moved to
		741	the left or top edge (for C<$xalign> or C<$yalign>), C<0.5> means it is
		742	exactly centered and C<1> means it touches the right or bottom edge.
		743
		744	Example: remove any visible border around an image, center it vertically but move
		745	it to the right hand side.
		746
		747	align 1, 0.5, pad $img
		748
		749	=item center $img
		750
		751	=item center $width, $height, $img
		752
		753	Centers the image, i.e. the center of the image is moved to the center of
		754	the terminal window (or the box specified by C<$width> and C<$height> if
		755	given).
		756
		757	Example: load an image and center it.
		758
		759	center keep { pad load "mybg.png" }
525		760
526	=item rootalign $img	761	=item rootalign $img
527		762
528	Moves the image so that it appears glued to the screen as opposed to the	763	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	764	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	765	exactly equivalent to C<move -TX, -TY>, that is, it moves the image to the
531	top left of the screen.	766	top left of the screen.
532		767
533	Example: load a background image, put it in mirror mode and root align it.	768	Example: load a background image, put it in mirror mode and root align it.
534		769
535	rootalign mirror load "mybg.png"	770	rootalign keep { mirror load "mybg.png" }
536		771
537	Example: take the screen background and align it, giving the illusion of	772	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.	773	transparency as long as the window isn't in front of other windows.
539		774
540	rootalign root	775	rootalign root
541		776
542	=cut	777	=cut
543		778
544	sub move($$;$) {	779	sub move($$;$) {
545	my $img = pop->clone;	780	my $img = pop->clone;
546	$img->move ($_[0], $_[1]);	781	$img->move ($_[0], $_[1]);
547	$img	782	$img
548	}	783	}
549		784
		785	sub align($;$$) {
		786	my $img = pop;
		787
		788	move $_[0] * (TW - $img->w),
		789	$_[1] * (TH - $img->h),
		790	$img
		791	}
		792
		793	sub center($;$$) {
		794	my $img = pop;
		795	my $w = $_[0] || TW;
		796	my $h = $_[1] || TH;
		797
		798	move 0.5 * ($w - $img->w), 0.5 * ($h - $img->h), $img
		799	}
		800
550	sub rootalign($) {	801	sub rootalign($) {
551	move -TX, -TY, $_[0]	802	move -TX, -TY, $_[0]
552	}	803	}
553		804
		805	=item rotate $center_x, $center_y, $degrees, $img
		806
		807	Rotates the image clockwise by C<$degrees> degrees, around the point at
		808	C<$center_x> and C<$center_y> (specified as factor of image width/height).
		809
		810	Example: rotate the image by 90 degrees around its center.
		811
		812	rotate 0.5, 0.5, 90, keep { load "$HOME/mybg.png" }
		813
		814	=cut
		815
		816	sub rotate($$$$) {
		817	my $img = pop;
		818	$img->rotate (
		819	$_[0] * ($img->w + $img->x),
		820	$_[1] * ($img->h + $img->y),
		821	$_[2] * (3.14159265 / 180),
		822	)
		823	}
		824
		825	=back
		826
		827	=head2 COLOUR MODIFICATIONS
		828
		829	The following operators change the pixels of the image.
		830
		831	=over
		832
		833	=item tint $color, $img
		834
		835	Tints the image in the given colour.
		836
		837	Example: tint the image red.
		838
		839	tint "red", load "rgb.png"
		840
		841	Example: the same, but specify the colour by component.
		842
		843	tint [1, 0, 0], load "rgb.png"
		844
		845	=cut
		846
		847	sub tint($$) {
		848	$_[1]->tint ($_[0])
		849	}
		850
		851	=item shade $factor, $img
		852
		853	Shade the image by the given factor.
		854
		855	=cut
		856
		857	sub shade($$) {
		858	$_[1]->shade ($_[0])
		859	}
		860
554	=item contrast $factor, $img	861	=item contrast $factor, $img
555		862
556	=item contrast $r, $g, $b, $img	863	=item contrast $r, $g, $b, $img
557		864
558	=item contrast $r, $g, $b, $a, $img	865	=item contrast $r, $g, $b, $a, $img
559		866
560	Adjusts the I<contrast> of an image.	867	Adjusts the I<contrast> of an image.
561		868
562	#TODO#	869	The first form applies a single C<$factor> to red, green and blue, the
		870	second form applies separate factors to each colour channel, and the last
		871	form includes the alpha channel.
563		872
		873	Values from 0 to 1 lower the contrast, values higher than 1 increase the
		874	contrast.
		875
		876	Due to limitations in the underlying XRender extension, lowering contrast
		877	also reduces brightness, while increasing contrast currently also
		878	increases brightness.
		879
564	=item brightness $factor, $img	880	=item brightness $bias, $img
565		881
566	=item brightness $r, $g, $b, $img	882	=item brightness $r, $g, $b, $img
567		883
568	=item brightness $r, $g, $b, $a, $img	884	=item brightness $r, $g, $b, $a, $img
569		885
570	Adjusts the brightness of an image.	886	Adjusts the brightness of an image.
		887
		888	The first form applies a single C<$bias> to red, green and blue, the
		889	second form applies separate biases to each colour channel, and the last
		890	form includes the alpha channel.
		891
		892	Values less than 0 reduce brightness, while values larger than 0 increase
		893	it. Useful range is from -1 to 1 - the former results in a black, the
		894	latter in a white picture.
		895
		896	Due to idiosyncrasies in the underlying XRender extension, biases less
		897	than zero can be I<very> slow.
		898
		899	You can also try the experimental(!) C<muladd> operator.
571		900
572	=cut	901	=cut
573		902
574	sub contrast($$;$$;$) {	903	sub contrast($$;$$;$) {
575	my $img = pop;	904	my $img = pop;
576	my ($r, $g, $b, $a) = @_;	905	my ($r, $g, $b, $a) = @_;
577		906
578	($g, $b) = ($r, $r) if @_ < 4;	907	($g, $b) = ($r, $r) if @_ < 3;
579	$a = 1 if @_ < 5;	908	$a = 1 if @_ < 4;
580		909
581	$img = $img->clone;	910	$img = $img->clone;
582	$img->contrast ($r, $g, $b, $a);	911	$img->contrast ($r, $g, $b, $a);
583	$img	912	$img
584	}	913	}
585		914
586	sub brightness($$;$$;$) {	915	sub brightness($$;$$;$) {
587	my $img = pop;	916	my $img = pop;
588	my ($r, $g, $b, $a) = @_;	917	my ($r, $g, $b, $a) = @_;
589		918
590	($g, $b) = ($r, $r) if @_ < 4;	919	($g, $b) = ($r, $r) if @_ < 3;
591	$a = 1 if @_ < 5;	920	$a = 1 if @_ < 4;
592		921
593	$img = $img->clone;	922	$img = $img->clone;
594	$img->brightness ($r, $g, $b, $a);	923	$img->brightness ($r, $g, $b, $a);
595	$img	924	$img
		925	}
		926
		927	=item muladd $mul, $add, $img # EXPERIMENTAL
		928
		929	First multiplies the pixels by C<$mul>, then adds C<$add>. This can be used
		930	to implement brightness and contrast at the same time, with a wider value
		931	range than contrast and brightness operators.
		932
		933	Due to numerous bugs in XRender implementations, it can also introduce a
		934	number of visual artifacts.
		935
		936	Example: increase contrast by a factor of C<$c> without changing image
		937	brightness too much.
		938
		939	muladd $c, (1 - $c) * 0.5, $img
		940
		941	=cut
		942
		943	sub muladd($$$) {
		944	$_[2]->muladd ($_[0], $_[1])
596	}	945	}
597		946
598	=item blur $radius, $img	947	=item blur $radius, $img
599		948
600	=item blur $radius_horz, $radius_vert, $img	949	=item blur $radius_horz, $radius_vert, $img
…		…
612	sub blur($$;$) {	961	sub blur($$;$) {
613	my $img = pop;	962	my $img = pop;
614	$img->blur ($_[0], @_ >= 2 ? $_[1] : $_[0])	963	$img->blur ($_[0], @_ >= 2 ? $_[1] : $_[0])
615	}	964	}
616		965
617	=item rotate $new_width, $new_height, $center_x, $center_y, $degrees	966	=item focus_fade $img
618		967
619	Rotates the image by C<$degrees> degrees, counter-clockwise, around the	968	=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		969
624	#TODO# new width, height, maybe more operators?	970	=item focus_fade $factor, $color, $img
625		971
626	Example: rotate the image by 90 degrees	972	Fades the image by the given factor (and colour) when focus is lost (the
		973	same as the C<-fade>/C<-fadecolor> command line options, which also supply
		974	the default values for C<factor> and C<$color>. Unlike with C<-fade>, the
		975	C<$factor> is a real value, not a percentage value (that is, 0..1, not
		976	0..100).
627		977
628	=cut	978	Example: do the right thing when focus fading is requested.
629		979
630	sub rotate($$$$$$) {	980	focus_fade load "mybg.jpg";
		981
		982	=cut
		983
		984	sub focus_fade($;$$) {
631	my $img = pop;	985	my $img = pop;
632	$img->rotate (	986
633	$_[0],	987	return $img
634	$_[1],	988	if FOCUS;
635	$_[2] * $img->w * .01,	989
636	$_[3] * $img->h * .01,	990	my $fade = @_ >= 1 ? $_[0] : defined $self->resource ("fade") ? $self->resource ("fade") * 0.01 : 0;
637	$_[4] * (3.14159265 / 180),	991	my $color = @_ >= 2 ? $_[1] : $self->resource ("color+" . &urxvt::Color_fade ()); # Color_fade not always available
638	)	992
		993	$img = $img->tint ($color) if $color ne "rgb:00/00/00";
		994	$img = $img->muladd (1 - $fade, 0) if $fade;
		995
		996	$img
639	}	997	}
640		998
641	=back	999	=back
642		1000
		1001	=head2 OTHER STUFF
		1002
		1003	Anything that didn't fit any of the other categories, even after applying
		1004	force and closing our eyes.
		1005
		1006	=over
		1007
		1008	=item keep { ... }
		1009
		1010	This operator takes a code block as argument, that is, one or more
		1011	statements enclosed by braces.
		1012
		1013	The trick is that this code block is only evaluated when the outcome
		1014	changes - on other calls the C<keep> simply returns the image it computed
		1015	previously (yes, it should only be used with images). Or in other words,
		1016	C<keep> I<caches> the result of the code block so it doesn't need to be
		1017	computed again.
		1018
		1019	This can be extremely useful to avoid redoing slow operations - for
		1020	example, if your background expression takes the root background, blurs it
		1021	and then root-aligns it it would have to blur the root background on every
		1022	window move or resize.
		1023
		1024	Another example is C<load>, which can be quite slow.
		1025
		1026	In fact, urxvt itself encloses the whole expression in some kind of
		1027	C<keep> block so it only is reevaluated as required.
		1028
		1029	Putting the blur into a C<keep> block will make sure the blur is only done
		1030	once, while the C<rootalign> is still done each time the window moves.
		1031
		1032	rootalign keep { blur 10, root }
		1033
		1034	This leaves the question of how to force reevaluation of the block,
		1035	in case the root background changes: If expression inside the block
		1036	is sensitive to some event (root background changes, window geometry
		1037	changes), then it will be reevaluated automatically as needed.
		1038
		1039	=back
		1040
		1041	=head1 OLD BACKGROUND IMAGE SETTINGS
		1042
		1043	This extension also provides support for the old options/resources and
		1044	OSC sequences for setting a background image. These settings are
		1045	B<deprecated> and will be removed in future versions.
		1046
		1047	=head2 OPTIONS AND RESOURCES
		1048
		1049	=over
		1050
		1051	=item B<-pixmap> I<file[;oplist]>
		1052
		1053	=item B<backgroundPixmap:> I<file[;oplist]>
		1054
		1055	Use the specified image file as the window's background and also
		1056	optionally specify a colon separated list of operations to modify it.
		1057	Note that you may need to quote the C<;> character when using the
		1058	command line option, as C<;> is usually a metacharacter in shells.
		1059	Supported operations are:
		1060
		1061	=over
		1062
		1063	=item B<WxH+X+Y>
		1064
		1065	sets scale and position. B<"W" / "H"> specify the horizontal/vertical
		1066	scale (percent), and B<"X" / "Y"> locate the image centre (percent). A
		1067	scale of 0 disables scaling.
		1068
		1069	=item B<op=tile>
		1070
		1071	enables tiling
		1072
		1073	=item B<op=keep-aspect>
		1074
		1075	maintain the image aspect ratio when scaling
		1076
		1077	=item B<op=root-align>
		1078
		1079	use the position of the terminal window relative to the root window as
		1080	the image offset, simulating a root window background
		1081
		1082	=back
		1083
		1084	The default scale and position setting is C<100x100+50+50>.
		1085	Alternatively, a predefined set of templates can be used to achieve
		1086	the most common setups:
		1087
		1088	=over
		1089
		1090	=item B<style=tiled>
		1091
		1092	the image is tiled with no scaling. Equivalent to 0x0+0+0:op=tile
		1093
		1094	=item B<style=aspect-stretched>
		1095
		1096	the image is scaled to fill the whole window maintaining the aspect
		1097	ratio and centered. Equivalent to 100x100+50+50:op=keep-aspect
		1098
		1099	=item B<style=stretched>
		1100
		1101	the image is scaled to fill the whole window. Equivalent to 100x100
		1102
		1103	=item B<style=centered>
		1104
		1105	the image is centered with no scaling. Equivalent to 0x0+50+50
		1106
		1107	=item B<style=root-tiled>
		1108
		1109	the image is tiled with no scaling and using 'root' positioning.
		1110	Equivalent to 0x0:op=tile:op=root-align
		1111
		1112	=back
		1113
		1114	If multiple templates are specified the last one wins. Note that a
		1115	template overrides all the scale, position and operations settings.
		1116
		1117	If used in conjunction with pseudo-transparency, the specified image
		1118	will be blended over the transparent background using alpha-blending.
		1119
		1120	=item B<-tr>|B<+tr>
		1121
		1122	=item B<transparent:> I<boolean>
		1123
		1124	Turn on/off pseudo-transparency by using the root pixmap as background.
		1125
		1126	=item B<-tint> I<colour>
		1127
		1128	=item B<tintColor:> I<colour>
		1129
		1130	Tint the transparent background with the given colour. Note that a
		1131	black tint yields a completely black image while a white tint yields
		1132	the image unchanged.
		1133
		1134	=item B<-sh> I<number>
		1135
		1136	=item B<shading:> I<number>
		1137
		1138	Darken (0 .. 99) or lighten (101 .. 200) the transparent background.
		1139	A value of 100 means no shading.
		1140
		1141	=item B<-blr> I<HxV>
		1142
		1143	=item B<blurRadius:> I<HxV>
		1144
		1145	Apply gaussian blur with the specified radius to the transparent
		1146	background. If a single number is specified, the vertical and
		1147	horizontal radii are considered to be the same. Setting one of the
		1148	radii to 1 and the other to a large number creates interesting effects
		1149	on some backgrounds. The maximum radius value is 128. An horizontal or
		1150	vertical radius of 0 disables blurring.
		1151
		1152	=back
		1153
		1154	=head2 OSC sequences
		1155
		1156	This extension will react to the following OSC sequences. Note that
		1157	this extension will not be autoloaded when these are used currently,
		1158	so to make urxvt recognize them, you have to enable the C<background>
		1159	extension. One way to achieve that is to use the C<--background-expr ''>
		1160	command line argument or by specifying an empty C<URxvt.background.expr:>>
		1161	resource.
		1162
		1163	=over
		1164
		1165	=item B<< C<ESC ] 705 ; Pt ST> >> Change transparent background tint colour to B<< C<Pt> >>.
		1166
		1167	=item B<< C<ESC ] 20 ; Pt ST> >> Change/Query background image
		1168	parameters: the value of B<< C<Pt> >> can be one of the following
		1169	commands:
		1170
		1171	=over
		1172
		1173	=item B<< C<?> >>
		1174
		1175	display scale and position in the title
		1176
		1177	=item B<< C<;WxH+X+Y> >>
		1178
		1179	change scale and/or position
		1180
		1181	=item B<< C<FILE;WxH+X+Y> >>
		1182
		1183	change background image
		1184
		1185	=back
		1186
		1187	=cut
		1188
		1189	sub keep(&) {
		1190	my $id = $_[0]+0;
		1191
		1192	local $frame = $self->{frame_cache}{$id} ||= [$frame];
		1193
		1194	unless ($frame->[FR_CACHE]) {
		1195	$frame->[FR_CACHE] = [ $_[0]() ];
		1196
		1197	my $self = $self;
		1198	my $frame = $frame;
		1199	Scalar::Util::weaken $frame;
		1200	$self->compile_frame ($frame, sub {
		1201	# clear this frame cache, also for all parents
		1202	for (my $frame = $frame; $frame; $frame = $frame->[0]) {
		1203	undef $frame->[FR_CACHE];
		1204	}
		1205
		1206	$self->recalculate;
		1207	});
		1208	};
		1209
		1210	# in scalar context we always return the first original result, which
		1211	# is not quite how perl works.
		1212	wantarray
		1213	? @{ $frame->[FR_CACHE] }
		1214	: $frame->[FR_CACHE][0]
		1215	}
		1216
		1217	# sub keep_clear() {
		1218	# delete $self->{frame_cache};
		1219	# }
		1220
		1221	=back
		1222
643	=cut	1223	=cut
644		1224
645	}	1225	}
646		1226
647	sub parse_expr {	1227	sub parse_expr {
648	my $expr = eval "sub {\npackage urxvt::bgdsl;\n#line 0 'background expression'\n$_[0]\n}";	1228	my ($expr) = @_;
		1229
		1230	# an empty expression is valid and represents the default background
		1231	if ($expr !~ /\S/) {
		1232	$expr = sub {
		1233	undef
		1234	};
		1235	} else {
		1236	$expr = eval
		1237	"sub {\n"
		1238	. "package urxvt::bgdsl;\n"
		1239	. "#line 0 'background expression'\n"
		1240	. "$expr\n"
		1241	. "}";
649	die if $@;	1242	die if $@;
		1243	}
		1244
650	$expr	1245	$expr
651	}	1246	}
652		1247
653	# compiles a parsed expression	1248	# compiles a parsed expression
654	sub set_expr {	1249	sub set_expr {
655	my ($self, $expr) = @_;	1250	my ($self, $expr) = @_;
656		1251
		1252	$self->{root} = []; # the outermost frame
657	$self->{expr} = $expr;	1253	$self->{expr} = $expr;
658	$self->recalculate;	1254	$self->recalculate;
		1255	}
		1256
		1257	# takes a hash of sensitivity indicators and installs watchers
		1258	sub compile_frame {
		1259	my ($self, $frame, $cb) = @_;
		1260
		1261	my $state = $frame->[urxvt::bgdsl::FR_STATE] ||= {};
		1262	my $again = $frame->[urxvt::bgdsl::FR_AGAIN];
		1263
		1264	# don't keep stuff alive
		1265	Scalar::Util::weaken $state;
		1266
		1267	if ($again->{nested}) {
		1268	$state->{nested} = 1;
		1269	} else {
		1270	delete $state->{nested};
		1271	}
		1272
		1273	if (my $interval = $again->{time}) {
		1274	$state->{time} = [$interval, urxvt::timer->new->after ($interval)->interval ($interval)]
		1275	if $state->{time}[0] != $interval;
		1276
		1277	# callback *might* have changed, although we could just rule that out
		1278	$state->{time}[1]->cb (sub {
		1279	++$state->{counter};
		1280	$cb->();
		1281	});
		1282	} else {
		1283	delete $state->{time};
		1284	}
		1285
		1286	if ($again->{position}) {
		1287	$state->{position} = $self->on (position_change => $cb);
		1288	} else {
		1289	delete $state->{position};
		1290	}
		1291
		1292	if ($again->{size}) {
		1293	$state->{size} = $self->on (size_change => $cb);
		1294	} else {
		1295	delete $state->{size};
		1296	}
		1297
		1298	if ($again->{rootpmap}) {
		1299	$state->{rootpmap} = $self->on (rootpmap_change => $cb);
		1300	} else {
		1301	delete $state->{rootpmap};
		1302	}
		1303
		1304	if ($again->{focus}) {
		1305	$state->{focus} = $self->on (focus_in => $cb, focus_out => $cb);
		1306	} else {
		1307	delete $state->{focus};
		1308	}
659	}	1309	}
660		1310
661	# evaluate the current bg expression	1311	# evaluate the current bg expression
662	sub recalculate {	1312	sub recalculate {
663	my ($arg_self) = @_;	1313	my ($arg_self) = @_;
…		…
671	return;	1321	return;
672	}	1322	}
673		1323
674	$arg_self->{next_refresh} = urxvt::NOW + $MIN_INTERVAL;	1324	$arg_self->{next_refresh} = urxvt::NOW + $MIN_INTERVAL;
675		1325
		1326	unless ($arg_self->has_render) {
		1327	warn "background extension needs RENDER extension 0.11 or higher, ignoring background-expr.\n";
		1328	return;
		1329	}
		1330
676	# set environment to evaluate user expression	1331	# set environment to evaluate user expression
677		1332
678	local $self = $arg_self;	1333	local $self = $arg_self;
679
680	local $HOME = $ENV{HOME};	1334	local $HOME = $ENV{HOME};
681	local $old = $self->{state};	1335	local $frame = $self->{root};
682	local $new = my $state = $self->{state} = {};
683		1336
684	($x, $y, $w, $h) =
685	$self->background_geometry ($self->{border});	1337	($x, $y, $w, $h) = $self->background_geometry ($self->{border});
		1338	$focus = $self->focus;
686		1339
687	# evaluate user expression	1340	# evaluate user expression
688		1341
689	my $img = eval { $self->{expr}->() };	1342	my @img = eval { $self->{expr}->() };
690	warn $@ if $@;#d#	1343	die $@ if $@;
		1344	die "background-expr did not return anything.\n" unless @img;
		1345
		1346	if ($img[0]) {
		1347	die "background-expr: expected image(s), got something else.\n"
691	die if !UNIVERSAL::isa $img, "urxvt::img";	1348	if grep { !UNIVERSAL::isa $_, "urxvt::img" } @img;
692		1349
693	$state->{size_sensitive} = 1	1350	my $img = urxvt::bgdsl::merge @img;
		1351
		1352	$frame->[urxvt::bgdsl::FR_AGAIN]{size} = 1
694	if $img->repeat_mode != urxvt::RepeatNormal;	1353	if $img->repeat_mode != urxvt::RepeatNormal;
695		1354
696	# if the expression is sensitive to external events, prepare reevaluation then	1355	# if the expression is sensitive to external events, prepare reevaluation then
		1356	$self->compile_frame ($frame, sub { $arg_self->recalculate });
697		1357
698	my $repeat;	1358	# clear stuff we no longer need
699		1359
700	if (my $again = $state->{again}) {	1360	# unless (%{ $frame->[FR_STATE] }) {
701	$repeat = 1;	1361	# delete $self->{state};
702	my $self = $self;	1362	# 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	}	1363	# }
710		1364
711	if (delete $state->{position_sensitive}) {	1365	# set background pixmap
712	$repeat = 1;	1366
713	$self->enable (position_change => sub { $_[0]->recalculate });	1367	$self->set_background ($img, $self->{border});
714	} else {	1368	} else {
715	$self->disable ("position_change");	1369	$self->clr_background;
716	}	1370	}
717		1371
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);	1372	$self->scr_recolor (0);
745	$self->want_refresh;	1373	$self->want_refresh;
746	}	1374	}
747		1375
		1376	sub old_bg_opts {
		1377	my ($self, $arg) = @_;
		1378
		1379	$arg or return;
		1380
		1381	my @str = split /;/, $arg;
		1382
		1383	return unless $str[0] or $self->{bg_opts}->{path};
		1384
		1385	my $bg_opts = $self->{bg_opts};
		1386
		1387	if ($str[0]) {
		1388	$bg_opts->{tile} = 0;
		1389	$bg_opts->{keep_aspect} = 0;
		1390	$bg_opts->{root_align} = 0;
		1391	$bg_opts->{h_scale} = $bg_opts->{v_scale} = 100;
		1392	$bg_opts->{h_align} = $bg_opts->{v_align} = 50;
		1393	$bg_opts->{path} = $str[0];
		1394	}
		1395
		1396	my @oplist = split /:/, $str[1];
		1397
		1398	for (@oplist) {
		1399	if (/style=tiled/i) {
		1400	$bg_opts->{tile} = 1;
		1401	$bg_opts->{keep_aspect} = 0;
		1402	$bg_opts->{root_align} = 0;
		1403	$bg_opts->{h_scale} = $bg_opts->{v_scale} = 0;
		1404	$bg_opts->{h_align} = $bg_opts->{v_align} = 0;
		1405	} elsif (/style=aspect-stretched/i) {
		1406	$bg_opts->{tile} = 0;
		1407	$bg_opts->{keep_aspect} = 1;
		1408	$bg_opts->{root_align} = 0;
		1409	$bg_opts->{h_scale} = $bg_opts->{v_scale} = 100;
		1410	$bg_opts->{h_align} = $bg_opts->{v_align} = 50;
		1411	} elsif (/style=stretched/i) {
		1412	$bg_opts->{tile} = 0;
		1413	$bg_opts->{keep_aspect} = 0;
		1414	$bg_opts->{root_align} = 0;
		1415	$bg_opts->{h_scale} = $bg_opts->{v_scale} = 100;
		1416	$bg_opts->{h_align} = $bg_opts->{v_align} = 50;
		1417	} elsif (/style=centered/i) {
		1418	$bg_opts->{tile} = 0;
		1419	$bg_opts->{keep_aspect} = 0;
		1420	$bg_opts->{root_align} = 0;
		1421	$bg_opts->{h_scale} = $bg_opts->{v_scale} = 0;
		1422	$bg_opts->{h_align} = $bg_opts->{v_align} = 50;
		1423	} elsif (/style=root-tiled/i) {
		1424	$bg_opts->{tile} = 1;
		1425	$bg_opts->{keep_aspect} = 0;
		1426	$bg_opts->{root_align} = 1;
		1427	$bg_opts->{h_scale} = $bg_opts->{v_scale} = 0;
		1428	$bg_opts->{h_align} = $bg_opts->{v_align} = 0;
		1429	} elsif (/op=tile/i) {
		1430	$bg_opts->{tile} = 1;
		1431	} elsif (/op=keep-aspect/i) {
		1432	$bg_opts->{keep_aspect} = 1;
		1433	} elsif (/op=root-align/i) {
		1434	$bg_opts->{root_align} = 1;
		1435	} elsif (/^ =? ([0-9]+)? (?:[xX] ([0-9]+))? ([+-][0-9]+)? ([+-][0-9]+)? $/x) {
		1436	my ($w, $h, $x, $y) = ($1, $2, $3, $4);
		1437
		1438	if ($str[0]) {
		1439	$w = $h unless defined $w;
		1440	$h = $w unless defined $h;
		1441	$y = $x unless defined $y;
		1442	}
		1443
		1444	$bg_opts->{h_scale} = $w if defined $w;
		1445	$bg_opts->{v_scale} = $h if defined $h;
		1446	$bg_opts->{h_align} = $x if defined $x;
		1447	$bg_opts->{v_align} = $y if defined $y;
		1448	}
		1449	}
		1450	}
		1451
		1452	# helper function, quote string as perl without allowing
		1453	# any code execution or other shenanigans. does not
		1454	# support binary NULs in string.
		1455	sub q0 {
		1456	(my $str = shift) =~ s/\x00//g; # make sure there really aren't any embedded NULs
		1457	"q\x00\Q$str\E\x00"
		1458	}
		1459
		1460	sub old_bg_expr {
		1461	my ($self) = @_;
		1462
		1463	my $expr;
		1464
		1465	my $bg_opts = $self->{bg_opts};
		1466
		1467	if ($bg_opts->{root} =~ /^\s*(?:true|yes|on|1)\s*$/i) {
		1468	$expr .= "tile (";
		1469
		1470	my $shade = $bg_opts->{shade};
		1471
		1472	if ($shade) {
		1473	$shade = List::Util::min $shade, 200;
		1474	$shade = List::Util::max $shade, -100;
		1475	$shade = 200 - (100 + $shade) if $shade < 0;
		1476
		1477	$shade = $shade * 0.01 - 1;
		1478	$expr .= "shade $shade, ";
		1479	}
		1480
		1481	my $tint = $bg_opts->{tint};
		1482
		1483	if ($tint) {
		1484	$tint = q0 $tint;
		1485	$expr .= "tint $tint,";
		1486	}
		1487
		1488	my $blur = $bg_opts->{blur};
		1489
		1490	if ($blur and $blur =~ /^ =? ([0-9]+)? (?:[xX] ([0-9]+))? $/x) {
		1491	my $hr = defined $1 ? $1 : 1;
		1492	my $vr = defined $2 ? $2 : $hr;
		1493
		1494	if ($hr != 0 and $vr != 0) {
		1495	$expr .= "blur $hr, $vr, ";
		1496	}
		1497	}
		1498
		1499	$expr .= "rootalign root)";
		1500	}
		1501
		1502	if ($bg_opts->{path}) {
		1503	my $file_expr;
		1504	my $h_scale = $bg_opts->{h_scale} * 0.01;
		1505	my $v_scale = $bg_opts->{v_scale} * 0.01;
		1506	my $h_align = $bg_opts->{h_align} * 0.01;
		1507	my $v_align = $bg_opts->{v_align} * 0.01;
		1508
		1509	if (!$bg_opts->{tile}) {
		1510	$file_expr .= "pad (";
		1511	} else {
		1512	$file_expr .= "tile (";
		1513	}
		1514
		1515	if ($bg_opts->{root_align}) {
		1516	$file_expr .= "rootalign ";
		1517	} else {
		1518	$file_expr .= "align $h_align, $v_align, ";
		1519	}
		1520
		1521	if ($h_scale != 0 and $v_scale != 0) {
		1522	my $op = $bg_opts->{keep_aspect} ? "fit" : "resize";
		1523	$file_expr .= "$op TW * $h_scale, TH * $v_scale, ";
		1524	}
		1525
		1526	my $path = q0 $bg_opts->{path};
		1527
		1528	$file_expr .= "keep { load $path })";
		1529
		1530	if ($expr) {
		1531	$expr .= ", tint (\"[50]white\", $file_expr)";
		1532	} else {
		1533	$expr = $file_expr;
		1534	}
		1535	}
		1536
		1537	$expr
		1538	}
		1539
		1540	sub find_resource {
		1541	my ($self, $res, $opt) = @_;
		1542
		1543	my $v = $self->x_resource ($opt);
		1544	$v = $self->x_resource ($res) unless defined $v;
		1545
		1546	$v
		1547	}
		1548
		1549	sub parse_bgopts {
		1550	my ($self) = @_;
		1551
		1552	my $expr = $self->x_resource ("%.expr");
		1553
		1554	if (!$expr) {
		1555	$self->{bg_opts} = { h_scale => 100, v_scale => 100,
		1556	h_align => 50, v_align => 50 };
		1557
		1558	$self->{bg_opts}{shade} = $self->find_resource ("shading", "sh");
		1559	$self->{bg_opts}{tint} = $self->find_resource ("tintColor", "tint");
		1560	$self->{bg_opts}{blur} = $self->find_resource ("blurRadius", "blr");
		1561	$self->{bg_opts}{root} = $self->find_resource ("transparent", "tr");
		1562
		1563	$self->old_bg_opts ($self->find_resource ("backgroundPixmap", "pixmap"));
		1564	$expr = $self->old_bg_expr;
		1565	}
		1566
		1567	$self->set_expr (parse_expr $expr);
		1568	$self->{border} = $self->x_resource_boolean ("%.border");
		1569
		1570	$MIN_INTERVAL = $self->x_resource ("%.interval");
		1571	}
		1572
748	sub on_start {	1573	sub on_start {
749	my ($self) = @_;	1574	my ($self) = @_;
750		1575
751	my $expr = $self->x_resource ("background.expr")	1576	$self->parse_bgopts;
752	or return;
753
754	$self->set_expr (parse_expr $expr);
755	$self->{border} = $self->x_resource_boolean ("background.border");
756		1577
757	()	1578	()
758	}	1579	}
759		1580
		1581	sub on_osc_seq {
		1582	my ($self, $op, $arg) = @_;
		1583
		1584	$op eq "20" or $op eq "706"
		1585	or return;
		1586
		1587	$self->{bg_opts}
		1588	or $self->parse_bgopts;
		1589
		1590	if ($op eq "20") {
		1591	if ($arg eq "?") {
		1592	my $h_scale = $self->{bg_opts}{h_scale};
		1593	my $v_scale = $self->{bg_opts}{v_scale};
		1594	my $h_align = $self->{bg_opts}{h_align};
		1595	my $v_align = $self->{bg_opts}{v_align};
		1596	$self->cmd_parse ("\033]2;[${h_scale}x${v_scale}+${h_align}+${v_align}]\007");
		1597	} else {
		1598	$self->old_bg_opts ($arg);
		1599	my $expr = $self->old_bg_expr;
		1600	$self->set_expr (parse_expr $expr) if $expr;
		1601	}
		1602	} elsif ($op eq "705") {
		1603	$self->{bg_opts}{tint} = $arg;
		1604	my $expr = $self->old_bg_expr;
		1605	$self->set_expr (parse_expr $expr) if $expr;
		1606	}
		1607
		1608	1
		1609	}
		1610

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