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Revision 1.38 by root, Fri Jun 8 21:48:07 2012 UTC vs.
Revision 1.108 by root, Tue Nov 29 05:45:43 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	#:META:RESOURCE:%.interval:seconds:minimum time between updates
		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
5		18
6	#TODO: once, rootalign	19	=head1 NAME
7		20
8	=head1 background - manage terminal background	21	background - manage terminal background
9		22
10	=head2 SYNOPSIS	23	=head1 SYNOPSIS
11		24
12	urxvt --background-expr 'background expression'	25	urxvt --background-expr 'background expression'
13	--background-border	26	--background-border
		27	--background-interval seconds
14		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 }
		52
15	=head2 DESCRIPTION	53	=head1 DESCRIPTION
16		54
17	This extension manages the terminal background by creating a picture that	55	This extension manages the terminal background by creating a picture that
18	is behind the text, replacing the normal background colour.	56	is behind the text, replacing the normal background colour.
19		57
20	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
21	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.
22		60
23	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
24	to be as simple as possible.	62	designed to be as simple as possible.
25		63
26	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
27	use:	65	use:
28		66
29	urxvt --background-expr 'scale load "/path/to/mybg.png"'	67	urxvt --background-expr 'scale keep { load "/path/to/mybg.png" }'
30		68
31	Or specified as a X resource:	69	Or specified as a X resource:
32		70
33	URxvt.background-expr: scale load "/path/to/mybg.png"	71	URxvt.background.expr: scale keep { load "/path/to/mybg.png" }
34		72
35	=head2 THEORY OF OPERATION	73	=head1 THEORY OF OPERATION
36		74
37	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
38	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
39	extended as necessary to cover the whole terminal window, and is set as a	77	extended as necessary to cover the whole terminal window, and is set as a
40	background pixmap.	78	background pixmap.
…		…
51	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
52	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
53	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
54	timer elapses), then the expression will be evaluated again.	92	timer elapses), then the expression will be evaluated again.
55		93
56	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"
57	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
58	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
59	example. That ensures that the picture always fills the terminal, even	97	example. That ensures that the picture always fills the terminal, even
60	after it's size changes.	98	after its size changes.
61		99
62	=head3 EXPRESSIONS	100	=head2 EXPRESSIONS
63		101
64	Expressions are normal Perl expressions, in fact, they are Perl blocks -	102	Expressions are normal Perl expressions, in fact, they are Perl blocks -
65	which means you could use multiple lines and statements:	103	which means you could use multiple lines and statements:
66		104
		105	scale keep {
67	again 3600;	106	again 3600;
68	if (localtime now)[6]) {	107	if (localtime now)[6]) {
69	return scale load "$HOME/weekday.png";	108	return load "$HOME/weekday.png";
70	} else {	109	} else {
71	return scale load "$HOME/sunday.png";	110	return load "$HOME/sunday.png";
		111	}
72	}	112	}
73		113
74	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
75	background on sundays, and F<weekday.png> on all other days.	116	Sundays, and F<weekday.png> on all other days.
76		117
77	Fortunately, we expect that most expressions will be much simpler, with	118	Fortunately, we expect that most expressions will be much simpler, with
78	little Perl knowledge needed.	119	little Perl knowledge needed.
79		120
80	Basically, you always start with a function that "generates" an image	121	Basically, you always start with a function that "generates" an image
…		…
97	its result becomes the argument to the C<scale> function.	138	its result becomes the argument to the C<scale> function.
98		139
99	Many operators also allow some parameters preceding the input image	140	Many operators also allow some parameters preceding the input image
100	that modify its behaviour. For example, C<scale> without any additional	141	that modify its behaviour. For example, C<scale> without any additional
101	arguments scales the image to size of the terminal window. If you specify	142	arguments scales the image to size of the terminal window. If you specify
102	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):
103		145
104	scale 200, load "$HOME/mypic.png"	146	scale 2, load "$HOME/mypic.png"
105		147
106	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>
107	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
108	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
109	commas.	151	commas.
110		152
111	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
112	horizontal and vertical dimensions. For example, this halves the image	154	horizontal and vertical dimensions. For example, this halves the image
113	width and doubles the image height:	155	width and doubles the image height:
114		156
115	scale 50, 200, load "$HOME/mypic.png"	157	scale 0.5, 2, load "$HOME/mypic.png"
116		158
117	TODO	159	IF you try out these expressions, you might suffer from some sluggishness,
		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:
118		163
119	=head3 CYCLES AND CACHING	164	scale 0.5, 2, keep { load "$HOME/mypic.png" }
120		165
121	TODO	166	The C<keep> operator executes all the statements inside the braces only
		167	once, or when it thinks the outcome might change. In other cases it
		168	returns the last value computed by the brace block.
122		169
123	Each time the expression is reevaluated, a new cycle is said to have begun. Many operators	170	This means that the C<load> is only executed once, which makes it much
124	cache their results till the next cycle. For example	171	faster, but also means that more memory is being used, because the loaded
		172	image must be kept in memory at all times. In this expression, the
		173	trade-off is likely worth it.
125		174
		175	But back to effects: Other effects than scaling are also readily
		176	available, for example, you can tile the image to fill the whole window,
		177	instead of resizing it:
		178
		179	tile keep { load "$HOME/mypic.png" }
		180
		181	In fact, images returned by C<load> are in C<tile> mode by default, so the
		182	C<tile> operator is kind of superfluous.
		183
		184	Another common effect is to mirror the image, so that the same edges
		185	touch:
		186
		187	mirror keep { load "$HOME/mypic.png" }
		188
		189	Another common background expression is:
		190
		191	rootalign root
		192
		193	This one first takes a snapshot of the screen background image, and then
		194	moves it to the upper left corner of the screen (as opposed to the upper
		195	left corner of the terminal window)- the result is pseudo-transparency:
		196	the image seems to be static while the window is moved around.
		197
		198	=head2 COLOUR SPECIFICATIONS
		199
		200	Whenever an operator expects a "colour", then this can be specified in one
		201	of two ways: Either as string with an X11 colour specification, such as:
		202
		203	"red" # named colour
		204	"#f00" # simple rgb
		205	"[50]red" # red with 50% alpha
		206	"TekHVC:300/50/50" # anything goes
		207
		208	OR as an array reference with one, three or four components:
		209
		210	[0.5] # 50% gray, 100% alpha
		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
		213
		214	=head2 CACHING AND SENSITIVITY
		215
		216	Since some operations (such as C<load> and C<blur>) can take a long time,
		217	caching results can be very important for a smooth operation. Caching can
		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.
		221
		222	=head3 C<keep { ... }> caching
		223
		224	The most important way to cache expensive operations is to use C<keep {
		225	... }>. The C<keep> operator takes a block of multiple statements enclosed
		226	by C<{}> and keeps the return value in memory.
		227
		228	An expression can be "sensitive" to various external events, such as
		229	scaling or moving the window, root background changes and timers. Simply
		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.
		261
126	=head2 REFERENCE	262	=head1 REFERENCE
127		263
128	=head3 COMMAND LINE SWITCHES	264	=head2 COMMAND LINE SWITCHES
129		265
130	=over 4	266	=over
131		267
132	=item --background-expr perl-expression	268	=item --background-expr perl-expression
133		269
134	Specifies the Perl expression to evaluate.	270	Specifies the Perl expression to evaluate.
135		271
…		…
139	overwriting borders and any other areas, such as the scrollbar.	275	overwriting borders and any other areas, such as the scrollbar.
140		276
141	Specifying this flag changes the behaviour, so that the image only	277	Specifying this flag changes the behaviour, so that the image only
142	replaces the background of the character area.	278	replaces the background of the character area.
143		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
144	=back	289	=back
145		290
146	=cut	291	=cut
147		292
148	our $EXPR;#d#	293	our %_IMG_CACHE;
149	#$EXPR = 'move W * 0.1, -H * 0.1, resize W * 0.5, H * 0.5, repeat_none load "opensource.png"';
150	$EXPR = 'move -TX, -TY, load "argb.png"';
151	#$EXPR = '
152	# rotate W, H, 50, 50, counter 1/59.95, repeat_mirror,
153	# clip X, Y, W, H, repeat_mirror,
154	# load "/root/pix/das_fette_schwein.jpg"
155	#';
156	#$EXPR = 'solid "red"';
157	#$EXPR = 'blur root, 10, 10'
158	#$EXPR = 'blur move (root, -x, -y), 5, 5'
159	#resize load "/root/pix/das_fette_schwein.jpg", w, h
160
161	our $HOME;	294	our $HOME;
162	our ($self, $old, $new);	295	our ($self, $frame);
163	our ($x, $y, $w, $h);	296	our ($x, $y, $w, $h, $focus);
164		297
165	# enforce at least this interval between updates	298	# enforce at least this interval between updates
166	our $MIN_INTERVAL = 1/100;	299	our $MIN_INTERVAL = 6/59.951;
167		300
168	{	301	{
169	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);
170		310
171	=head2 PROVIDERS/GENERATORS	311	=head2 PROVIDERS/GENERATORS
172		312
173	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
174	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
175	points to get an image you can play with.	315	points to get an image you can play with.
176		316
177	=over 4	317	=over
178		318
179	=item load $path	319	=item load $path
180		320
181	Loads the image at the given C<$path>. The image is set to plane tiling	321	Loads the image at the given C<$path>. The image is set to plane tiling
182	mode.	322	mode.
183		323
184	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.
185		326
		327	=item load_uc $path
		328
		329	Load uncached - same as load, but does not cache the image, which means it
		330	is I<always> loaded from the filesystem again, even if another copy of it
		331	is in memory at the time.
		332
186	=cut	333	=cut
		334
		335	sub load_uc($) {
		336	$self->new_img_from_file ($_[0])
		337	}
187		338
188	sub load($) {	339	sub load($) {
189	my ($path) = @_;	340	my ($path) = @_;
190		341
191	$new->{load}{$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	}
192	}	347	}
193		348
194	=item root	349	=item root
195		350
196	Returns the root window pixmap, that is, hopefully, the background image	351	Returns the root window pixmap, that is, hopefully, the background image
197	of your screen. The image is set to extend mode.	352	of your screen.
198		353
199	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
200	reevaluated when the bg image changes.	355	reevaluated when the bg image changes.
201		356
202	=cut	357	=cut
203		358
204	sub root() {	359	sub root() {
205	$new->{rootpmap_sensitive} = 1;	360	$frame->[FR_AGAIN]{rootpmap} = 1;
206	die "root op not supported, exg, we need you";	361	$self->new_img_from_root
207	}	362	}
208		363
209	=item solid $colour	364	=item solid $colour
210		365
211	=item solid $width, $height, $colour	366	=item solid $width, $height, $colour
212		367
213	Creates a new image and completely fills it with the given colour. The	368	Creates a new image and completely fills it with the given colour. The
214	image is set to tiling mode.	369	image is set to tiling mode.
215		370
216	If <$width> and C<$height> are omitted, it creates a 1x1 image, which is	371	If C<$width> and C<$height> are omitted, it creates a 1x1 image, which is
217	useful for solid backgrounds or for use in filtering effects.	372	useful for solid backgrounds or for use in filtering effects.
218		373
219	=cut	374	=cut
220		375
221	sub solid($$;$) {	376	sub solid($;$$) {
222	my $colour = pop;	377	my $colour = pop;
223		378
224	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);
225	$img->fill ($colour);	380	$img->fill ($colour);
226	$img	381	$img
227	}	382	}
228		383
229	=back	384	=item clone $img
230		385
231	=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.
232		388
233	The following functions provide variable data such as the terminal
234	window dimensions. Most of them make your expression sensitive to some
235	events, for example using C<TW> (terminal width) means your expression is
236	evaluated again when the terminal is resized.
237
238	=over 4
239
240	=item TX
241
242	=item TY
243
244	Return the X and Y coordinates of the terminal window (the terminal
245	window is the full window by default, and the character area only when in
246	border-respect mode).
247
248	Using these functions make your expression sensitive to window moves.
249
250	These functions are mainly useful to align images to the root window.
251
252	Example: load an image and align it so it looks as if anchored to the
253	background.
254
255	move -TX, -TY, load "mybg.png"
256
257	=item TW
258
259	Return the width (C<TW>) and height (C<TH>) of the terminal window (the
260	terminal window is the full window by default, and the character area only
261	when in border-respect mode).
262
263	Using these functions make your expression sensitive to window resizes.
264
265	These functions are mainly useful to scale images, or to clip images to
266	the window size to conserve memory.
267
268	Example: take the screen background, clip it to the window size, blur it a
269	bit, align it to the window position and use it as background.
270
271	clip move -TX, -TY, blur 5, root
272
273	=cut	389	=cut
274		390
275	sub TX() { $new->{position_sensitive} = 1; $x }
276	sub TY() { $new->{position_sensitive} = 1; $y }
277	sub TW() { $new->{size_sensitive} = 1; $w }
278	sub TH() { $new->{size_sensitive} = 1; $h }
279
280	=item now
281
282	Returns the current time as (fractional) seconds since the epoch.
283
284	Using this expression does I<not> make your expression sensitive to time,
285	but the next two functions do.
286
287	=item again $seconds
288
289	When this function is used the expression will be reevaluated again in
290	C<$seconds> seconds.
291
292	Example: load some image and rotate it according to the time of day (as if it were
293	the hour pointer of a clock). Update this image every minute.
294
295	again 60; rotate TW, TH, 50, 50, (now % 86400) * -720 / 86400, scale load "myclock.png"
296
297	=item counter $seconds
298
299	Like C<again>, but also returns an increasing counter value, starting at
300	0, which might be useful for some simple animation effects.
301
302	=cut
303
304	sub now() { urxvt::NOW }
305
306	sub again($) {
307	$new->{again} = $_[0];
308	}
309
310	sub counter($) {	391	sub clone($) {
311	$new->{again} = $_[0];	392	$_[0]->clone
312	$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
313	}	437	}
314		438
315	=back	439	=back
316		440
317	=head2 TILING MODES	441	=head2 TILING MODES
318		442
319	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
320	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.
321		445
322	=over 4	446	=over
323		447
324	=item tile $img	448	=item tile $img
325		449
326	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
327	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.
…		…
350	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
351	image over another image or the background colour while leaving all	475	image over another image or the background colour while leaving all
352	background pixels outside the image unchanged.	476	background pixels outside the image unchanged.
353		477
354	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
355	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
356	in alpha mode, else background colour).	480	in alpha mode, else background colour).
357		481
358	pad load "mybg.png"	482	pad load "mybg.png"
359		483
360	=item extend $img	484	=item extend $img
361		485
362	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
363	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
364	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
365	same values as the pixels near the edge.	489	same values as the pixels near the edge.
366		490
367	Example: just for curiosity, how does this pixel extension stuff work?	491	Example: just for curiosity, how does this pixel extension stuff work?
368		492
…		…
394	$img	518	$img
395	}	519	}
396		520
397	=back	521	=back
398		522
399	=head2 PIXEL OPERATORS	523	=head2 VARIABLE VALUES
400		524
401	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.
402		530
403	=over 4	531	=over
404		532
405	=item clone $img	533	=item TX
406		534
407	Returns an exact copy of the image.	535	=item TY
408		536
409	=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).
410		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} = $_[0];
		621	}
		622
411	sub clone($) {	623	sub counter($) {
412	$_[0]->clone	624	$frame->[FR_AGAIN]{time} = $_[0];
		625	$frame->[FR_STATE]{counter} + 0
413	}	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
414		635
415	=item clip $img	636	=item clip $img
416		637
417	=item clip $width, $height, $img	638	=item clip $width, $height, $img
418		639
…		…
421	Clips an image to the given rectangle. If the rectangle is outside the	642	Clips an image to the given rectangle. If the rectangle is outside the
422	image area (e.g. when C<$x> or C<$y> are negative) or the rectangle is	643	image area (e.g. when C<$x> or C<$y> are negative) or the rectangle is
423	larger than the image, then the tiling mode defines how the extra pixels	644	larger than the image, then the tiling mode defines how the extra pixels
424	will be filled.	645	will be filled.
425		646
426	If C<$x> an C<$y> are missing, then C<0> is assumed for both.	647	If C<$x> and C<$y> are missing, then C<0> is assumed for both.
427		648
428	If C<$width> and C<$height> are missing, then the window size will be	649	If C<$width> and C<$height> are missing, then the window size will be
429	assumed.	650	assumed.
430		651
431	Example: load an image, blur it, and clip it to the window size to save	652	Example: load an image, blur it, and clip it to the window size to save
432	memory.	653	memory.
433		654
434	clip blur 10, load "mybg.png"	655	clip keep { blur 10, load "mybg.png" }
435		656
436	=cut	657	=cut
437		658
438	sub clip($;$$;$$) {	659	sub clip($;$$;$$) {
439	my $img = pop;	660	my $img = pop;
…		…
442	$img->sub_rect ($_[0], $_[1], $w, $h)	663	$img->sub_rect ($_[0], $_[1], $w, $h)
443	}	664	}
444		665
445	=item scale $img	666	=item scale $img
446		667
447	=item scale $size_percent, $img	668	=item scale $size_factor, $img
448		669
449	=item scale $width_percent, $height_percent, $img	670	=item scale $width_factor, $height_factor, $img
450		671
451	Scales the image by the given percentages in horizontal	672	Scales the image by the given factors in horizontal
452	(C<$width_percent>) and vertical (C<$height_percent>) direction.	673	(C<$width>) and vertical (C<$height>) direction.
453		674
454	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.
455		676
456	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
457	keeping aspect.	678	keeping aspect.
458		679
459	=item resize $width, $height, $img	680	=item resize $width, $height, $img
460		681
461	Resizes the image to exactly C<$width> times C<$height> pixels.	682	Resizes the image to exactly C<$width> times C<$height> pixels.
462		683
463	=cut	684	=item fit $img
464		685
465	#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, $img
		695
		696	Similar to C<fit>, but shrinks or grows until all of the area is covered
		697	by the image, so instead of potentially leaving borders, it will cut off
		698	image data that doesn't fit.
		699
		700	=cut
466		701
467	sub scale($;$;$) {	702	sub scale($;$;$) {
468	my $img = pop;	703	my $img = pop;
469		704
470	@_ == 2 ? $img->scale ($_[0] * $img->w * 0.01, $_[1] * $img->h * 0.01)	705	@_ == 2 ? $img->scale ($_[0] * $img->w, $_[1] * $img->h)
471	: @_ ? $img->scale ($_[0] * $img->w * 0.01, $_[0] * $img->h * 0.01)	706	: @_ ? $img->scale ($_[0] * $img->w, $_[0] * $img->h)
472	: $img->scale (TW, TH)	707	: $img->scale (TW, TH)
473	}	708	}
474		709
475	sub resize($$$) {	710	sub resize($$$) {
476	my $img = pop;	711	my $img = pop;
477	$img->scale ($_[0], $_[1])	712	$img->scale ($_[0], $_[1])
478	}	713	}
479		714
		715	sub fit($;$$) {
		716	my $img = pop;
		717	my $w = ($_[0] || TW) / $img->w;
		718	my $h = ($_[1] || TH) / $img->h;
		719	scale +(min $w, $h), $img
		720	}
		721
		722	sub cover($;$$) {
		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
480	=item move $dx, $dy, $img	729	=item move $dx, $dy, $img
481		730
482	Moves the image by C<$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
483	the vertical.	732	the vertical.
484		733
485	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.
486		735
487	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" }
488		760
489	=item rootalign $img	761	=item rootalign $img
490		762
491	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
492	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
493	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
494	top left of the screen.	766	top left of the screen.
495		767
496	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.
497		769
498	rootalign mirror load "mybg.png"	770	rootalign keep { mirror load "mybg.png" }
499		771
500	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
501	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.
502		774
503	rootalign root	775	rootalign root
504		776
505	=cut	777	=cut
506		778
507	sub move($$;$) {	779	sub move($$;$) {
508	my $img = pop->clone;	780	my $img = pop->clone;
509	$img->move ($_[0], $_[1]);	781	$img->move ($_[0], $_[1]);
510	$img	782	$img
511	}	783	}
512		784
		785	sub align($;$$) {
		786	my $img = pop;
		787
		788	move $_[0] * (TW - $img->w),
		789	$_[1] * (TH - $img->h),
		790	$img
		791	}
		792
		793	sub center($;$$) {
		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), $img
		799	}
		800
513	sub rootalign($) {	801	sub rootalign($) {
514	move -TX, -TY, $_[0]	802	move -TX, -TY, $_[0]
515	}	803	}
516		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($$) {
		858	$_[1]->shade ($_[0])
		859	}
		860
517	=item contrast $factor, $img	861	=item contrast $factor, $img
518		862
519	=item contrast $r, $g, $b, $img	863	=item contrast $r, $g, $b, $img
520		864
521	=item contrast $r, $g, $b, $a, $img	865	=item contrast $r, $g, $b, $a, $img
522		866
523	Adjusts the I<contrast> of an image.	867	Adjusts the I<contrast> of an image.
524		868
525	#TODO#	869	The first form applies a single C<$factor> to red, green and blue, the
		870	second form applies separate factors to each colour channel, and the last
		871	form includes the alpha channel.
526		872
		873	Values from 0 to 1 lower the contrast, values higher than 1 increase the
		874	contrast.
		875
		876	Due to limitations in the underlying XRender extension, lowering contrast
		877	also reduces brightness, while increasing contrast currently also
		878	increases brightness.
		879
527	=item brightness $factor, $img	880	=item brightness $bias, $img
528		881
529	=item brightness $r, $g, $b, $img	882	=item brightness $r, $g, $b, $img
530		883
531	=item brightness $r, $g, $b, $a, $img	884	=item brightness $r, $g, $b, $a, $img
532		885
533	Adjusts the brightness of an image.	886	Adjusts the brightness of an image.
		887
		888	The first form applies a single C<$bias> to red, green and blue, the
		889	second form applies separate biases to each colour channel, and the last
		890	form includes the alpha channel.
		891
		892	Values less than 0 reduce brightness, while values larger than 0 increase
		893	it. Useful range is from -1 to 1 - the former results in a black, the
		894	latter in a white picture.
		895
		896	Due to idiosyncrasies in the underlying XRender extension, biases less
		897	than zero can be I<very> slow.
		898
		899	You can also try the experimental(!) C<muladd> operator.
534		900
535	=cut	901	=cut
536		902
537	sub contrast($$;$$;$) {	903	sub contrast($$;$$;$) {
538	my $img = pop;	904	my $img = pop;
539	my ($r, $g, $b, $a) = @_;	905	my ($r, $g, $b, $a) = @_;
540		906
541	($g, $b) = ($r, $r) if @_ < 4;	907	($g, $b) = ($r, $r) if @_ < 3;
542	$a = 1 if @_ < 5;	908	$a = 1 if @_ < 4;
543		909
544	$img = $img->clone;	910	$img = $img->clone;
545	$img->contrast ($r, $g, $b, $a);	911	$img->contrast ($r, $g, $b, $a);
546	$img	912	$img
547	}	913	}
548		914
549	sub brightness($$;$$;$) {	915	sub brightness($$;$$;$) {
550	my $img = pop;	916	my $img = pop;
551	my ($r, $g, $b, $a) = @_;	917	my ($r, $g, $b, $a) = @_;
552		918
553	($g, $b) = ($r, $r) if @_ < 4;	919	($g, $b) = ($r, $r) if @_ < 3;
554	$a = 1 if @_ < 5;	920	$a = 1 if @_ < 4;
555		921
556	$img = $img->clone;	922	$img = $img->clone;
557	$img->brightness ($r, $g, $b, $a);	923	$img->brightness ($r, $g, $b, $a);
558	$img	924	$img
559	}	925	}
560		926
		927	=item muladd $mul, $add, $img # EXPERIMENTAL
		928
		929	First multiplies the pixels by C<$mul>, then adds C<$add>. This can be used
		930	to implement brightness and contrast at the same time, with a wider value
		931	range than contrast and brightness operators.
		932
		933	Due to numerous bugs in XRender implementations, it can also introduce a
		934	number of visual artifacts.
		935
		936	Example: increase contrast by a factor of C<$c> without changing image
		937	brightness too much.
		938
		939	muladd $c, (1 - $c) * 0.5, $img
		940
		941	=cut
		942
		943	sub muladd($$$) {
		944	$_[2]->muladd ($_[0], $_[1])
		945	}
		946
561	=item blur $radius, $img	947	=item blur $radius, $img
562		948
563	=item blur $radius_horz, $radius_vert, $img	949	=item blur $radius_horz, $radius_vert, $img
564		950
565	Gaussian-blurs the image with (roughly) C<$radius> pixel radius. The radii	951	Gaussian-blurs the image with (roughly) C<$radius> pixel radius. The radii
566	can also be specified separately.	952	can also be specified separately.
		953
		954	Blurring is often I<very> slow, at least compared or other
		955	operators. Larger blur radii are slower than smaller ones, too, so if you
		956	don't want to freeze your screen for long times, start experimenting with
		957	low values for radius (<5).
567		958
568	=cut	959	=cut
569		960
570	sub blur($$;$) {	961	sub blur($$;$) {
571	my $img = pop;	962	my $img = pop;
572	$img->blur ($_[0], @_ >= 2 ? $_[1] : $_[0])	963	$img->blur ($_[0], @_ >= 2 ? $_[1] : $_[0])
573	}	964	}
574		965
575	=item rotate $new_width, $new_height, $center_x, $center_y, $degrees	966	=item focus_fade $img
576		967
577	Rotates the image by C<$degrees> degrees, counter-clockwise, around the	968	=item focus_fade $factor, $img
578	pointer at C<$center_x> and C<$center_y> (specified as percentage of image
579	width/height), generating a new image with width C<$new_width> and height
580	C<$new_height>.
581		969
582	#TODO# new width, height, maybe more operators?	970	=item focus_fade $factor, $color, $img
583		971
584	Example: rotate the image by 90 degrees	972	Fades the image by the given factor (and colour) when focus is lost (the
		973	same as the C<-fade>/C<-fadecolor> command line options, which also supply
		974	the default values for C<factor> and C<$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).
585		977
586	=cut	978	Example: do the right thing when focus fading is requested.
587		979
588	sub rotate($$$$$$) {	980	focus_fade load "mybg.jpg";
		981
		982	=cut
		983
		984	sub focus_fade($;$$) {
589	my $img = pop;	985	my $img = pop;
590	$img->rotate (	986
591	$_[0],	987	return $img
592	$_[1],	988	if FOCUS;
593	$_[2] * $img->w * .01,	989
594	$_[3] * $img->h * .01,	990	my $fade = @_ >= 1 ? $_[0] : defined $self->resource ("fade") ? $self->resource ("fade") * 0.01 : 0;
595	$_[4] * (3.14159265 / 180),	991	my $color = @_ >= 2 ? $_[1] : $self->resource ("color+" . &urxvt::Color_fade ()); # Color_fade not always available
596	)	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
597	}	997	}
598		998
599	=back	999	=back
600		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
601	=cut	1223	=cut
602		1224
603	}	1225	}
604		1226
605	sub parse_expr {	1227	sub parse_expr {
606	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	. "}";
607	die if $@;	1242	die if $@;
		1243	}
		1244
608	$expr	1245	$expr
609	}	1246	}
610		1247
611	# compiles a parsed expression	1248	# compiles a parsed expression
612	sub set_expr {	1249	sub set_expr {
613	my ($self, $expr) = @_;	1250	my ($self, $expr) = @_;
614		1251
		1252	$self->{root} = []; # the outermost frame
615	$self->{expr} = $expr;	1253	$self->{expr} = $expr;
616	$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 $state->{focus};
		1308	}
617	}	1309	}
618		1310
619	# evaluate the current bg expression	1311	# evaluate the current bg expression
620	sub recalculate {	1312	sub recalculate {
621	my ($arg_self) = @_;	1313	my ($arg_self) = @_;
…		…
629	return;	1321	return;
630	}	1322	}
631		1323
632	$arg_self->{next_refresh} = urxvt::NOW + $MIN_INTERVAL;	1324	$arg_self->{next_refresh} = urxvt::NOW + $MIN_INTERVAL;
633		1325
		1326	unless ($arg_self->has_render) {
		1327	warn "background extension needs RENDER extension 0.11 or higher, ignoring background-expr.\n";
		1328	return;
		1329	}
		1330
634	# set environment to evaluate user expression	1331	# set environment to evaluate user expression
635		1332
636	local $self = $arg_self;	1333	local $self = $arg_self;
637
638	local $HOME = $ENV{HOME};	1334	local $HOME = $ENV{HOME};
639	local $old = $self->{state};	1335	local $frame = $self->{root};
640	local $new = my $state = $self->{state} = {};
641		1336
642	($x, $y, $w, $h) =
643	$self->background_geometry ($self->{border});	1337	($x, $y, $w, $h) = $self->background_geometry ($self->{border});
		1338	$focus = $self->focus;
644		1339
645	# evaluate user expression	1340	# evaluate user expression
646		1341
647	my $img = eval { $self->{expr}->() };	1342	my @img = eval { $self->{expr}->() };
648	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"
649	die if !UNIVERSAL::isa $img, "urxvt::img";	1348	if grep { !UNIVERSAL::isa $_, "urxvt::img" } @img;
650		1349
651	$state->{size_sensitive} = 1	1350	my $img = urxvt::bgdsl::merge @img;
		1351
		1352	$frame->[urxvt::bgdsl::FR_AGAIN]{size} = 1
652	if $img->repeat_mode != urxvt::RepeatNormal;	1353	if $img->repeat_mode != urxvt::RepeatNormal;
653		1354
654	# 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 });
655		1357
656	my $repeat;	1358	# clear stuff we no longer need
657		1359
658	if (my $again = $state->{again}) {	1360	# unless (%{ $frame->[FR_STATE] }) {
659	$repeat = 1;	1361	# delete $self->{state};
660	my $self = $self;	1362	# delete $self->{expr};
661	$state->{timer} = $again == $old->{again}
662	? $old->{timer}
663	: urxvt::timer->new->after ($again)->interval ($again)->cb (sub {
664	++$self->{counter};
665	$self->recalculate
666	});
667	}	1363	# }
668		1364
669	if (delete $state->{position_sensitive}) {	1365	# set background pixmap
670	$repeat = 1;	1366
671	$self->enable (position_change => sub { $_[0]->recalculate });	1367	$self->set_background ($img, $self->{border});
672	} else {	1368	} else {
673	$self->disable ("position_change");	1369	$self->clr_background;
674	}	1370	}
675		1371
676	if (delete $state->{size_sensitive}) {
677	$repeat = 1;
678	$self->enable (size_change => sub { $_[0]->recalculate });
679	} else {
680	$self->disable ("size_change");
681	}
682
683	if (delete $state->{rootpmap_sensitive}) {
684	$repeat = 1;
685	$self->enable (rootpmap_change => sub { $_[0]->recalculate });
686	} else {
687	$self->disable ("rootpmap_change");
688	}
689
690	# clear stuff we no longer need
691
692	%$old = ();
693
694	unless ($repeat) {
695	delete $self->{state};
696	delete $self->{expr};
697	}
698
699	# set background pixmap
700
701	$self->set_background ($img, $self->{border});
702	$self->scr_recolour (0);	1372	$self->scr_recolor (0);
703	$self->want_refresh;	1373	$self->want_refresh;
704	}	1374	}
705		1375
		1376	sub old_bg_opts {
		1377	my ($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 $y;
		1448	}
		1449	}
		1450	}
		1451
		1452	# helper function, quote string as perl without allowing
		1453	# any code execution or other shenanigans.
		1454	sub q0 {
		1455	"qq\x00\Q$_\E\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	$expr
		1536	}
		1537
		1538	sub find_resource {
		1539	my ($self, $res, $opt) = @_;
		1540
		1541	my $v = $self->x_resource ($opt);
		1542	$v = $self->x_resource ($res) unless defined $v;
		1543
		1544	$v
		1545	}
		1546
		1547	sub parse_bgopts {
		1548	my ($self) = @_;
		1549
		1550	my $expr = $self->x_resource ("%.expr");
		1551
		1552	if (!$expr) {
		1553	$self->{bg_opts} = { h_scale => 100, v_scale => 100,
		1554	h_align => 50, v_align => 50 };
		1555
		1556	$self->{bg_opts}{shade} = $self->find_resource ("shading", "sh");
		1557	$self->{bg_opts}{tint} = $self->find_resource ("tintColor", "tint");
		1558	$self->{bg_opts}{blur} = $self->find_resource ("blurRadius", "blr");
		1559	$self->{bg_opts}{root} = $self->find_resource ("transparent", "tr");
		1560
		1561	$self->old_bg_opts ($self->find_resource ("backgroundPixmap", "pixmap"));
		1562	$expr = $self->old_bg_expr;
		1563	}
		1564
		1565	$self->set_expr (parse_expr $expr);
		1566	$self->{border} = $self->x_resource_boolean ("%.border");
		1567
		1568	$MIN_INTERVAL = $self->x_resource ("%.interval");
		1569	}
		1570
706	sub on_start {	1571	sub on_start {
707	my ($self) = @_;	1572	my ($self) = @_;
708		1573
709	my $expr = $self->x_resource ("background.expr")	1574	$self->parse_bgopts;
710	or return;
711
712	$self->set_expr (parse_expr $expr);
713	$self->{border} = $self->x_resource_boolean ("background.border");
714		1575
715	()	1576	()
716	}	1577	}
717		1578
		1579	sub on_osc_seq {
		1580	my ($self, $op, $arg) = @_;
		1581
		1582	$op eq "20" or $op eq "706"
		1583	or return;
		1584
		1585	$self->{bg_opts}
		1586	or $self->parse_bgopts;
		1587
		1588	if ($op eq "20") {
		1589	if ($arg eq "?") {
		1590	my $h_scale = $self->{bg_opts}{h_scale};
		1591	my $v_scale = $self->{bg_opts}{v_scale};
		1592	my $h_align = $self->{bg_opts}{h_align};
		1593	my $v_align = $self->{bg_opts}{v_align};
		1594	$self->cmd_parse ("\033]2;[${h_scale}x${v_scale}+${h_align}+${v_align}]\007");
		1595	} else {
		1596	$self->old_bg_opts ($arg);
		1597	my $expr = $self->old_bg_expr;
		1598	$self->set_expr (parse_expr $expr) if $expr;
		1599	}
		1600	} elsif ($op eq "705") {
		1601	$self->{bg_opts}{tint} = $arg;
		1602	my $expr = $self->old_bg_expr;
		1603	$self->set_expr (parse_expr $expr) if $expr;
		1604	}
		1605
		1606	1
		1607	}
		1608

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