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

Comparing rxvt-unicode/src/perl/background (file contents):
Revision 1.44 by root, Sun Jun 10 11:31:22 2012 UTC vs.
Revision 1.64 by root, Tue Jun 19 20:49:53 2012 UTC

…		…
1	#! perl	1	#! perl
2		2
3	#:META:X_RESOURCE:%.expr:string:background expression	3	#:META:X_RESOURCE:%.expr:string:background expression
4	#:META:X_RESOURCE:%.border.:boolean:respect the terminal border	4	#:META:X_RESOURCE:%.border:boolean:respect the terminal border
5		5	#:META:X_RESOURCE:%.interval:seconds:minimum time between updates
6	#TODO: once, rootalign
7		6
8	=head1 NAME	7	=head1 NAME
9		8
10	background - manage terminal background	9	background - manage terminal background
11		10
12	=head1 SYNOPSIS	11	=head1 SYNOPSIS
13		12
14	urxvt --background-expr 'background expression'	13	urxvt --background-expr 'background expression'
15	--background-border	14	--background-border
		15	--background-interval seconds
16		16
17	=head1 DESCRIPTION	17	=head1 DESCRIPTION
18		18
19	This extension manages the terminal background by creating a picture that	19	This extension manages the terminal background by creating a picture that
20	is behind the text, replacing the normal background colour.	20	is behind the text, replacing the normal background colour.
26	to be as simple as possible.	26	to be as simple as possible.
27		27
28	For example, to load an image and scale it to the window size, you would	28	For example, to load an image and scale it to the window size, you would
29	use:	29	use:
30		30
31	urxvt --background-expr 'scale load "/path/to/mybg.png"'	31	urxvt --background-expr 'scale keep { load "/path/to/mybg.png" }'
32		32
33	Or specified as a X resource:	33	Or specified as a X resource:
34		34
35	URxvt.background-expr: scale load "/path/to/mybg.png"	35	URxvt.background-expr: scale keep { load "/path/to/mybg.png" }
36		36
37	=head1 THEORY OF OPERATION	37	=head1 THEORY OF OPERATION
38		38
39	At startup, just before the window is mapped for the first time, the	39	At startup, just before the window is mapped for the first time, the
40	expression is evaluated and must yield an image. The image is then	40	expression is evaluated and must yield an image. The image is then
…		…
53	If any of the parameters that the expression relies on changes (when the	53	If any of the parameters that the expression relies on changes (when the
54	window is moved or resized, its position or size changes; when the root	54	window is moved or resized, its position or size changes; when the root
55	pixmap is replaced by another one the root background changes; or when the	55	pixmap is replaced by another one the root background changes; or when the
56	timer elapses), then the expression will be evaluated again.	56	timer elapses), then the expression will be evaluated again.
57		57
58	For example, an expression such as C<scale load "$HOME/mybg.png"> scales the	58	For example, an expression such as C<scale keep { load "$HOME/mybg.png"
59	image to the window size, so it relies on the window size and will	59	}> scales the image to the window size, so it relies on the window size
60	be reevaluated each time it is changed, but not when it moves for	60	and will be reevaluated each time it is changed, but not when it moves for
61	example. That ensures that the picture always fills the terminal, even	61	example. That ensures that the picture always fills the terminal, even
62	after it's size changes.	62	after its size changes.
63		63
64	=head2 EXPRESSIONS	64	=head2 EXPRESSIONS
65		65
66	Expressions are normal Perl expressions, in fact, they are Perl blocks -	66	Expressions are normal Perl expressions, in fact, they are Perl blocks -
67	which means you could use multiple lines and statements:	67	which means you could use multiple lines and statements:
68		68
		69	scale keep {
69	again 3600;	70	again 3600;
70	if (localtime now)[6]) {	71	if (localtime now)[6]) {
71	return scale load "$HOME/weekday.png";	72	return load "$HOME/weekday.png";
72	} else {	73	} else {
73	return scale load "$HOME/sunday.png";	74	return load "$HOME/sunday.png";
		75	}
74	}	76	}
75		77
76	This expression gets evaluated once per hour. It will set F<sunday.png> as	78	This expression is evaluated once per hour. It will set F<sunday.png> as
77	background on Sundays, and F<weekday.png> on all other days.	79	background on Sundays, and F<weekday.png> on all other days.
78		80
79	Fortunately, we expect that most expressions will be much simpler, with	81	Fortunately, we expect that most expressions will be much simpler, with
80	little Perl knowledge needed.	82	little Perl knowledge needed.
81		83
…		…
115	horizontal and vertical dimensions. For example, this halves the image	117	horizontal and vertical dimensions. For example, this halves the image
116	width and doubles the image height:	118	width and doubles the image height:
117		119
118	scale 0.5, 2, load "$HOME/mypic.png"	120	scale 0.5, 2, load "$HOME/mypic.png"
119		121
120	Other effects than scalign are also readily available, for exmaple, you can	122	IF you try out these expressions, you might suffer from sluggishness,
121	tile the image to fill the whole window, instead of resizing it:	123	because each time the terminal is resized, it again loads the PNG image
		124	and scales it. Scaling is usually fats, but loading the image can be quite
		125	time consuming. This is where C<keep> comes in handy:
122		126
		127	scale 0.5, 2, keep { load "$HOME/mypic.png" }
		128
		129	The C<keep> operator executes all the statements inside the braces only
		130	once, or when it thinks the outcome might change. In other cases it
		131	returns the last value computed by the brace block.
		132
		133	This means that the C<load> is only executed once, which makes it much
		134	faster, but alos means that more memory is being used, because the loaded
		135	image must be kept in memory at all times. In this expression, the
		136	trade-off is likely worth it.
		137
		138	But back to effects: Other effects than scaling are also readily
		139	available, for example, you can tile the image to fill the whole window,
		140	instead of resizing it:
		141
123	tile load "$HOME/mypic.png"	142	tile keep { load "$HOME/mypic.png" }
124		143
125	In fact, images returned by C<load> are in C<tile> mode by default, so the C<tile> operator	144	In fact, images returned by C<load> are in C<tile> mode by default, so the
126	is kind of superfluous.	145	C<tile> operator is kind of superfluous.
127		146
128	Another common effect is to mirror the image, so that the same edges touch:	147	Another common effect is to mirror the image, so that the same edges
		148	touch:
129		149
130	mirror load "$HOME/mypic.png"	150	mirror keep { load "$HOME/mypic.png" }
131		151
132	This is also a typical background expression:	152	Another common background expression is:
133		153
134	rootalign root	154	rootalign root
135		155
136	It first takes a snapshot of the screen background image, and then	156	This one first takes a snapshot of the screen background image, and then
137	moves it to the upper left corner of the screen - the result is	157	moves it to the upper left corner of the screen (as opposed to the upepr
138	pseudo-transparency, as the image seems to be static while the window is	158	left corner of the terminal window)- the result is pseudo-transparency:
139	moved around.	159	the image seems to be static while the window is moved around.
140		160
141	=head2 CYCLES AND CACHING	161	=head2 CACHING AND SENSITIVITY
142		162
143	As has been mentioned before, the expression might be evaluated multiple	163	Since some operations (such as C<load> and C<blur>) can take a long time,
144	times. Each time the expression is reevaluated, a new cycle is said to	164	caching results can be very important for a smooth operation. Caching can
145	have begun. Many operators cache their results till the next cycle.	165	also be useful to reduce memory usage, though, for example, when an image
		166	is cached by C<load>, it could be shared by multiple terminal windows
		167	running inside urxvtd.
146		168
147	For example, the C<load> operator keeps a copy of the image. If it is	169	=head3 C<keep { ... }> caching
148	asked to load the same image on the next cycle it will not load it again,
149	but return the cached copy.
150		170
151	This only works for one cycle though, so as long as you load the same	171	The most important way to cache expensive operations is to use C<keep {
152	image every time, it will always be cached, but when you load a different	172	... }>. The C<keep> operator takes a block of multiple statements enclosed
153	image, it will forget about the first one.	173	by C<{}> and keeps the return value in memory.
154		174
155	This allows you to either speed things up by keeping multiple images in	175	An expression can be "sensitive" to various external events, such as
156	memory, or comserve memory by loading images more often.	176	scaling or moving the window, root backgorund changes and timers. Simply
		177	using an expression (such as C<scale> without parameters) that depend on
		178	certain changing values (called "variables"), or using those variables
		179	directly, will make an expression sensitive to these events - for example,
		180	using C<scale> or C<TW> will make the expression sensitive to the terminal
		181	size, and thus to resizing events.
157		182
158	For example, you can keep two images in memory and use a random one like	183	When such an event happens, C<keep> will automatically trigger a
159	this:	184	reevaluation of the whole expression with the new value of the expression.
160		185
161	my $img1 = load "img1.png";	186	C<keep> is most useful for expensive operations, such as C<blur>:
162	my $img2 = load "img2.png";
163	(0.5 > rand) ? $img1 : $img2
164		187
165	Since both images are "loaded" every time the expression is evaluated,	188	rootalign once { blur 20, root }
166	they are always kept in memory. Contrast this version:
167		189
168	my $path1 = "img1.png";	190	This makes a blurred copy of the root background once, and on subsequent
169	my $path2 = "img2.png";	191	calls, just root-aligns it. Since C<blur> is usually quite slow and
170	load ((0.5 > rand) ? $path1 : $path2)	192	C<rootalign> is quite fast, this trades extra memory (for the cached
		193	blurred pixmap) with speed (blur only needs to be redone when root
		194	changes).
171		195
172	Here, a path is selected randomly, and load is only called for one image,	196	=head3 C<load> caching
173	so keeps only one image in memory. If, on the next evaluation, luck	197
174	decides to use the other path, then it will have to load that image again.	198	The C<load> operator itself does not keep images in memory, but as long as
		199	the image is still in memory, C<load> will use the in-memory image instead
		200	of loading it freshly from disk.
		201
		202	That means that this expression:
		203
		204	keep { load "$HOME/path..." }
		205
		206	Not only caches the image in memory, other terminal instances that try to
		207	C<load> it can reuse that in-memory copy.
175		208
176	=head1 REFERENCE	209	=head1 REFERENCE
177		210
178	=head2 COMMAND LINE SWITCHES	211	=head2 COMMAND LINE SWITCHES
179		212
…		…
189	overwriting borders and any other areas, such as the scrollbar.	222	overwriting borders and any other areas, such as the scrollbar.
190		223
191	Specifying this flag changes the behaviour, so that the image only	224	Specifying this flag changes the behaviour, so that the image only
192	replaces the background of the character area.	225	replaces the background of the character area.
193		226
		227	=item --background-interval seconds
		228
		229	Since some operations in the underlying XRender extension can effectively
		230	freeze your X-server for prolonged time, this extension enforces a minimum
		231	time between updates, which is normally about 0.1 seconds.
		232
		233	If you want to do updates more often, you can decrease this safety
		234	interval with this switch.
		235
194	=back	236	=back
195		237
196	=cut	238	=cut
197		239
		240	our %_IMG_CACHE;
198	our $HOME;	241	our $HOME;
199	our ($self, $old, $new);	242	our ($self, $frame);
200	our ($x, $y, $w, $h);	243	our ($x, $y, $w, $h);
201		244
202	# enforce at least this interval between updates	245	# enforce at least this interval between updates
203	our $MIN_INTERVAL = 1/100;	246	our $MIN_INTERVAL = 6/59.951;
204		247
205	{	248	{
206	package urxvt::bgdsl; # background language	249	package urxvt::bgdsl; # background language
		250
		251	sub FR_PARENT() { 0 } # parent frame, if any - must be #0
		252	sub FR_CACHE () { 1 } # cached values
		253	sub FR_AGAIN () { 2 } # what this expr is sensitive to
		254	sub FR_STATE () { 3 } # watchers etc.
207		255
208	use List::Util qw(min max sum shuffle);	256	use List::Util qw(min max sum shuffle);
209		257
210	=head2 PROVIDERS/GENERATORS	258	=head2 PROVIDERS/GENERATORS
211		259
…		…
218	=item load $path	266	=item load $path
219		267
220	Loads the image at the given C<$path>. The image is set to plane tiling	268	Loads the image at the given C<$path>. The image is set to plane tiling
221	mode.	269	mode.
222		270
223	Loaded images will be cached for one cycle.	271	If the image is already in memory (e.g. because another temrinal instance
		272	uses it), then the in-memory copy us returned instead.
224		273
		274	=item load_uc $path
		275
		276	Load uncached - same as load, but does not cache the image, which means it
		277	is I<always> loaded from the filesystem again.
		278
225	=cut	279	=cut
		280
		281	sub load_uc($) {
		282	$self->new_img_from_file ($path)
		283	}
226		284
227	sub load($) {	285	sub load($) {
228	my ($path) = @_;	286	my ($path) = @_;
229		287
230	$new->{load}{$path} = $old->{load}{$path} \|\| $self->new_img_from_file ($path);	288	$_IMG_CACHE{$path} \|\| do {
		289	my $img = load_uc $path;
		290	Scalar::Util::weaken ($_IMG_CACHE{$path} = $img);
		291	$img
		292	}
231	}	293	}
232		294
233	=item root	295	=item root
234		296
235	Returns the root window pixmap, that is, hopefully, the background image	297	Returns the root window pixmap, that is, hopefully, the background image
236	of your screen. The image is set to extend mode.	298	of your screen.
237		299
238	This function makes your expression root sensitive, that means it will be	300	This function makes your expression root sensitive, that means it will be
239	reevaluated when the bg image changes.	301	reevaluated when the bg image changes.
240		302
241	=cut	303	=cut
242		304
243	sub root() {	305	sub root() {
244	$new->{rootpmap_sensitive} = 1;	306	$frame->[FR_AGAIN]{rootpmap} = 1;
245	die "root op not supported, exg, we need you";	307	$self->new_img_from_root
246	}	308	}
247		309
248	=item solid $colour	310	=item solid $colour
249		311
250	=item solid $width, $height, $colour	312	=item solid $width, $height, $colour
…		…
258	=cut	320	=cut
259		321
260	sub solid($;$$) {	322	sub solid($;$$) {
261	my $colour = pop;	323	my $colour = pop;
262		324
263	my $img = $self->new_img (urxvt::PictStandardARGB32, $_[0] \|\| 1, $_[1] \|\| 1);	325	my $img = $self->new_img (urxvt::PictStandardARGB32, 0, 0, $_[0] \|\| 1, $_[1] \|\| 1);
264	$img->fill ($colour);	326	$img->fill ($colour);
265	$img	327	$img
266	}	328	}
267		329
268	=back	330	=item clone $img
269		331
270	=head2 VARIABLES	332	Returns an exact copy of the image. This is useful if you want to have
		333	multiple copies of the same image to apply different effects to.
271		334
272	The following functions provide variable data such as the terminal window
273	dimensions. They are not (Perl-) variables, they jsut return stuff that
274	varies. Most of them make your expression sensitive to some events, for
275	example using C<TW> (terminal width) means your expression is evaluated
276	again when the terminal is resized.
277
278	=over 4
279
280	=item TX
281
282	=item TY
283
284	Return the X and Y coordinates of the terminal window (the terminal
285	window is the full window by default, and the character area only when in
286	border-respect mode).
287
288	Using these functions make your expression sensitive to window moves.
289
290	These functions are mainly useful to align images to the root window.
291
292	Example: load an image and align it so it looks as if anchored to the
293	background.
294
295	move -TX, -TY, load "mybg.png"
296
297	=item TW
298
299	Return the width (C<TW>) and height (C<TH>) of the terminal window (the
300	terminal window is the full window by default, and the character area only
301	when in border-respect mode).
302
303	Using these functions make your expression sensitive to window resizes.
304
305	These functions are mainly useful to scale images, or to clip images to
306	the window size to conserve memory.
307
308	Example: take the screen background, clip it to the window size, blur it a
309	bit, align it to the window position and use it as background.
310
311	clip move -TX, -TY, blur 5, root
312
313	=cut	335	=cut
314		336
315	sub TX() { $new->{position_sensitive} = 1; $x }
316	sub TY() { $new->{position_sensitive} = 1; $y }
317	sub TW() { $new->{size_sensitive} = 1; $w }
318	sub TH() { $new->{size_sensitive} = 1; $h }
319
320	=item now
321
322	Returns the current time as (fractional) seconds since the epoch.
323
324	Using this expression does I<not> make your expression sensitive to time,
325	but the next two functions do.
326
327	=item again $seconds
328
329	When this function is used the expression will be reevaluated again in
330	C<$seconds> seconds.
331
332	Example: load some image and rotate it according to the time of day (as if it were
333	the hour pointer of a clock). Update this image every minute.
334
335	again 60; rotate TW, TH, 50, 50, (now % 86400) * -720 / 86400, scale load "myclock.png"
336
337	=item counter $seconds
338
339	Like C<again>, but also returns an increasing counter value, starting at
340	0, which might be useful for some simple animation effects.
341
342	=cut
343
344	sub now() { urxvt::NOW }
345
346	sub again($) {
347	$new->{again} = $_[0];
348	}
349
350	sub counter($) {	337	sub clone($) {
351	$new->{again} = $_[0];	338	$_[0]->clone
352	$self->{counter} + 0
353	}	339	}
354		340
355	=back	341	=item merge $img ...
		342
		343	Takes any number of images and merges them together, creating a single
		344	image containing them all. The tiling mode of the first image is used as
		345	the tiling mdoe of the resulting image.
		346
		347	This function is called automatically when an expression returns multiple
		348	images.
		349
		350	=cut
		351
		352	sub merge(@) {
		353	return $_[0] unless $#_;
		354
		355	# rather annoyingly clumsy, but optimisation is for another time
		356
		357	my $x0 = +1e9;
		358	my $y0 = +1e9;
		359	my $x1 = -1e9;
		360	my $y1 = -1e9;
		361
		362	for (@_) {
		363	my ($x, $y, $w, $h) = $_->geometry;
		364
		365	$x0 = $x if $x0 > $x;
		366	$y0 = $y if $y0 > $y;
		367
		368	$x += $w;
		369	$y += $h;
		370
		371	$x1 = $x if $x1 < $x;
		372	$y1 = $y if $y1 < $y;
		373	}
		374
		375	my $base = $self->new_img (urxvt::PictStandardARGB32, $x0, $y0, $x1 - $x0, $y1 - $y0);
		376	$base->repeat_mode ($_[0]->repeat_mode);
		377	$base->fill ([0, 0, 0, 0]);
		378
		379	$base->draw ($_)
		380	for @_;
		381
		382	$base
		383	}
356		384
357	=head2 TILING MODES	385	=head2 TILING MODES
358		386
359	The following operators modify the tiling mode of an image, that is, the	387	The following operators modify the tiling mode of an image, that is, the
360	way that pixels outside the image area are painted when the image is used.	388	way that pixels outside the image area are painted when the image is used.
…		…
390	become transparent. This mode is most useful when you want to place an	418	become transparent. This mode is most useful when you want to place an
391	image over another image or the background colour while leaving all	419	image over another image or the background colour while leaving all
392	background pixels outside the image unchanged.	420	background pixels outside the image unchanged.
393		421
394	Example: load an image and display it in the upper left corner. The rest	422	Example: load an image and display it in the upper left corner. The rest
395	of the space is left "empty" (transparent or wahtever your compisotr does	423	of the space is left "empty" (transparent or whatever your compositor does
396	in alpha mode, else background colour).	424	in alpha mode, else background colour).
397		425
398	pad load "mybg.png"	426	pad load "mybg.png"
399		427
400	=item extend $img	428	=item extend $img
401		429
402	Extends the image over the whole plane, using the closest pixel in the	430	Extends the image over the whole plane, using the closest pixel in the
403	area outside the image. This mode is mostly useful when you more complex	431	area outside the image. This mode is mostly useful when you use more complex
404	filtering operations and want the pixels outside the image to have the	432	filtering operations and want the pixels outside the image to have the
405	same values as the pixels near the edge.	433	same values as the pixels near the edge.
406		434
407	Example: just for curiosity, how does this pixel extension stuff work?	435	Example: just for curiosity, how does this pixel extension stuff work?
408		436
…		…
434	$img	462	$img
435	}	463	}
436		464
437	=back	465	=back
438		466
439	=head2 PIXEL OPERATORS	467	=head2 VARIABLE VALUES
440		468
441	The following operators modify the image pixels in various ways.	469	The following functions provide variable data such as the terminal window
		470	dimensions. They are not (Perl-) variables, they just return stuff that
		471	varies. Most of them make your expression sensitive to some events, for
		472	example using C<TW> (terminal width) means your expression is evaluated
		473	again when the terminal is resized.
442		474
443	=over 4	475	=over 4
444		476
445	=item clone $img	477	=item TX
446		478
447	Returns an exact copy of the image.	479	=item TY
448		480
449	=cut	481	Return the X and Y coordinates of the terminal window (the terminal
		482	window is the full window by default, and the character area only when in
		483	border-respect mode).
450		484
		485	Using these functions make your expression sensitive to window moves.
		486
		487	These functions are mainly useful to align images to the root window.
		488
		489	Example: load an image and align it so it looks as if anchored to the
		490	background (that's exactly what C<rootalign> does btw.):
		491
		492	move -TX, -TY, keep { load "mybg.png" }
		493
		494	=item TW
		495
		496	Return the width (C<TW>) and height (C<TH>) of the terminal window (the
		497	terminal window is the full window by default, and the character area only
		498	when in border-respect mode).
		499
		500	Using these functions make your expression sensitive to window resizes.
		501
		502	These functions are mainly useful to scale images, or to clip images to
		503	the window size to conserve memory.
		504
		505	Example: take the screen background, clip it to the window size, blur it a
		506	bit, align it to the window position and use it as background.
		507
		508	clip move -TX, -TY, keep { blur 5, root }
		509
		510	=cut
		511
		512	sub TX() { $frame->[FR_AGAIN]{position} = 1; $x }
		513	sub TY() { $frame->[FR_AGAIN]{position} = 1; $y }
		514	sub TW() { $frame->[FR_AGAIN]{size} = 1; $w }
		515	sub TH() { $frame->[FR_AGAIN]{size} = 1; $h }
		516
		517	=item now
		518
		519	Returns the current time as (fractional) seconds since the epoch.
		520
		521	Using this expression does I<not> make your expression sensitive to time,
		522	but the next two functions do.
		523
		524	=item again $seconds
		525
		526	When this function is used the expression will be reevaluated again in
		527	C<$seconds> seconds.
		528
		529	Example: load some image and rotate it according to the time of day (as if it were
		530	the hour pointer of a clock). Update this image every minute.
		531
		532	again 60;
		533	rotate 50, 50, (now % 86400) * -72 / 8640, scale keep { load "myclock.png" }
		534
		535	=item counter $seconds
		536
		537	Like C<again>, but also returns an increasing counter value, starting at
		538	0, which might be useful for some simple animation effects.
		539
		540	=cut
		541
		542	sub now() { urxvt::NOW }
		543
		544	sub again($) {
		545	$frame->[FR_AGAIN]{time} = $_[0];
		546	}
		547
451	sub clone($) {	548	sub counter($) {
452	$_[0]->clone	549	$frame->[FR_AGAIN]{time} = $_[0];
		550	$frame->[FR_STATE]{counter} + 0
453	}	551	}
		552
		553	=back
		554
		555	=head2 SHAPE CHANGING OPERATORS
		556
		557	The following operators modify the shape, size or position of the image.
		558
		559	=over 4
454		560
455	=item clip $img	561	=item clip $img
456		562
457	=item clip $width, $height, $img	563	=item clip $width, $height, $img
458		564
…		…
469	assumed.	575	assumed.
470		576
471	Example: load an image, blur it, and clip it to the window size to save	577	Example: load an image, blur it, and clip it to the window size to save
472	memory.	578	memory.
473		579
474	clip blur 10, load "mybg.png"	580	clip keep { blur 10, load "mybg.png" }
475		581
476	=cut	582	=cut
477		583
478	sub clip($;$$;$$) {	584	sub clip($;$$;$$) {
479	my $img = pop;	585	my $img = pop;
…		…
552		658
553	Example: move the image right by 20 pixels and down by 30.	659	Example: move the image right by 20 pixels and down by 30.
554		660
555	move 20, 30, ...	661	move 20, 30, ...
556		662
		663	=item align $xalign, $yalign, $img
		664
		665	Aligns the image according to a factor - C<0> means the image is moved to
		666	the left or top edge (for C<$xalign> or C<$yalign>), C<0.5> means it is
		667	exactly centered and C<1> means it touches the right or bottom edge.
		668
		669	Example: remove any visible border around an image, center it vertically but move
		670	it to the right hand side.
		671
		672	align 1, 0.5, pad $img
		673
557	=item center $img	674	=item center $img
558		675
559	=item center $width, $height, $img	676	=item center $width, $height, $img
560		677
561	Centers the image, i.e. the center of the image is moved to the center of	678	Centers the image, i.e. the center of the image is moved to the center of
562	the terminal window (or the box specified by C<$width> and C<$height> if	679	the terminal window (or the box specified by C<$width> and C<$height> if
563	given).	680	given).
		681
		682	Example: load an image and center it.
		683
		684	center keep { pad load "mybg.png" }
564		685
565	=item rootalign $img	686	=item rootalign $img
566		687
567	Moves the image so that it appears glued to the screen as opposed to the	688	Moves the image so that it appears glued to the screen as opposed to the
568	window. This gives the illusion of a larger area behind the window. It is	689	window. This gives the illusion of a larger area behind the window. It is
569	exactly equivalent to C<move -TX, -TY>, that is, it moves the image to the	690	exactly equivalent to C<move -TX, -TY>, that is, it moves the image to the
570	top left of the screen.	691	top left of the screen.
571		692
572	Example: load a background image, put it in mirror mode and root align it.	693	Example: load a background image, put it in mirror mode and root align it.
573		694
574	rootalign mirror load "mybg.png"	695	rootalign keep { mirror load "mybg.png" }
575		696
576	Example: take the screen background and align it, giving the illusion of	697	Example: take the screen background and align it, giving the illusion of
577	transparency as long as the window isn't in front of other windows.	698	transparency as long as the window isn't in front of other windows.
578		699
579	rootalign root	700	rootalign root
580		701
581	=cut	702	=cut
582		703
583	sub move($$;$) {	704	sub move($$;$) {
584	my $img = pop->clone;	705	my $img = pop->clone;
585	$img->move ($_[0], $_[1]);	706	$img->move ($_[0], $_[1]);
586	$img	707	$img
587	}	708	}
588		709
		710	sub align($;$$) {
		711	my $img = pop;
		712
		713	move $_[0] * (TW - $img->w),
		714	$_[1] * (TH - $img->h),
		715	$img
		716	}
		717
589	sub center($;$$) {	718	sub center($;$$) {
590	my $img = pop;	719	my $img = pop;
591	my $w = $_[0] \|\| TW;	720	my $w = $_[0] \|\| TW;
592	my $h = $_[0] \|\| TH;	721	my $h = $_[1] \|\| TH;
593		722
594	move 0.5 * ($w - $img->w), 0.5 * ($h - $img->h), $img	723	move 0.5 * ($w - $img->w), 0.5 * ($h - $img->h), $img
595	}	724	}
596		725
597	sub rootalign($) {	726	sub rootalign($) {
598	move -TX, -TY, $_[0]	727	move -TX, -TY, $_[0]
599	}	728	}
600		729
		730	=item rotate $center_x, $center_y, $degrees, $img
		731
		732	Rotates the image clockwise by C<$degrees> degrees, around the point at
		733	C<$center_x> and C<$center_y> (specified as factor of image width/height).
		734
		735	Example: rotate the image by 90 degrees around it's center.
		736
		737	rotate 0.5, 0.5, 90, keep { load "$HOME/mybg.png" }
		738
		739	=cut
		740
		741	sub rotate($$$$) {
		742	my $img = pop;
		743	$img->rotate (
		744	$_[0] * ($img->w + $img->x),
		745	$_[1] * ($img->h + $img->y),
		746	$_[2] * (3.14159265 / 180),
		747	)
		748	}
		749
		750	=back
		751
		752	=head2 COLOUR MODIFICATIONS
		753
		754	The following operators change the pixels of the image.
		755
		756	=over 4
		757
601	=item contrast $factor, $img	758	=item contrast $factor, $img
602		759
603	=item contrast $r, $g, $b, $img	760	=item contrast $r, $g, $b, $img
604		761
605	=item contrast $r, $g, $b, $a, $img	762	=item contrast $r, $g, $b, $a, $img
606		763
607	Adjusts the I<contrast> of an image.	764	Adjusts the I<contrast> of an image.
608		765
609	#TODO#	766	The first form applies a single C<$factor> to red, green and blue, the
		767	second form applies separate factors to each colour channel, and the last
		768	form includes the alpha channel.
610		769
		770	Values from 0 to 1 lower the contrast, values higher than 1 increase the
		771	contrast.
		772
		773	Due to limitations in the underlying XRender extension, lowering contrast
		774	also reduces brightness, while increasing contrast currently also
		775	increases brightness.
		776
611	=item brightness $factor, $img	777	=item brightness $bias, $img
612		778
613	=item brightness $r, $g, $b, $img	779	=item brightness $r, $g, $b, $img
614		780
615	=item brightness $r, $g, $b, $a, $img	781	=item brightness $r, $g, $b, $a, $img
616		782
617	Adjusts the brightness of an image.	783	Adjusts the brightness of an image.
		784
		785	The first form applies a single C<$bias> to red, green and blue, the
		786	second form applies separate biases to each colour channel, and the last
		787	form includes the alpha channel.
		788
		789	Values less than 0 reduce brightness, while values larger than 0 increase
		790	it. Useful range is from -1 to 1 - the former results in a black, the
		791	latter in a white picture.
		792
		793	Due to idiosyncrasies in the underlying XRender extension, biases less
		794	than zero can be I<very> slow.
618		795
619	=cut	796	=cut
620		797
621	sub contrast($$;$$;$) {	798	sub contrast($$;$$;$) {
622	my $img = pop;	799	my $img = pop;
623	my ($r, $g, $b, $a) = @_;	800	my ($r, $g, $b, $a) = @_;
624		801
625	($g, $b) = ($r, $r) if @_ < 4;	802	($g, $b) = ($r, $r) if @_ < 3;
626	$a = 1 if @_ < 5;	803	$a = 1 if @_ < 4;
627		804
628	$img = $img->clone;	805	$img = $img->clone;
629	$img->contrast ($r, $g, $b, $a);	806	$img->contrast ($r, $g, $b, $a);
630	$img	807	$img
631	}	808	}
632		809
633	sub brightness($$;$$;$) {	810	sub brightness($$;$$;$) {
634	my $img = pop;	811	my $img = pop;
635	my ($r, $g, $b, $a) = @_;	812	my ($r, $g, $b, $a) = @_;
636		813
637	($g, $b) = ($r, $r) if @_ < 4;	814	($g, $b) = ($r, $r) if @_ < 3;
638	$a = 1 if @_ < 5;	815	$a = 1 if @_ < 4;
639		816
640	$img = $img->clone;	817	$img = $img->clone;
641	$img->brightness ($r, $g, $b, $a);	818	$img->brightness ($r, $g, $b, $a);
642	$img	819	$img
643	}	820	}
…		…
659	sub blur($$;$) {	836	sub blur($$;$) {
660	my $img = pop;	837	my $img = pop;
661	$img->blur ($_[0], @_ >= 2 ? $_[1] : $_[0])	838	$img->blur ($_[0], @_ >= 2 ? $_[1] : $_[0])
662	}	839	}
663		840
664	=item rotate $new_width, $new_height, $center_x, $center_y, $degrees
665
666	Rotates the image by C<$degrees> degrees, counter-clockwise, around the
667	pointer at C<$center_x> and C<$center_y> (specified as factor of image
668	width/height), generating a new image with width C<$new_width> and height
669	C<$new_height>.
670
671	#TODO# new width, height, maybe more operators?
672
673	Example: rotate the image by 90 degrees
674
675	=cut
676
677	sub rotate($$$$$$) {
678	my $img = pop;
679	$img->rotate (
680	$_[0],
681	$_[1],
682	$_[2] * $img->w,
683	$_[3] * $img->h,
684	$_[4] * (3.14159265 / 180),
685	)
686	}
687
688	=back	841	=back
689		842
		843	=head2 OTHER STUFF
		844
		845	Anything that didn't fit any of the other categories, even after applying
		846	force and closing our eyes.
		847
		848	=over 4
		849
		850	=item once { ... }
		851
		852	This function takes a code block as argument, that is, one or more
		853	statements enclosed by braces.
		854
		855	The trick is that this code block is only evaluated once - future calls
		856	will simply return the original image (yes, it should only be used with
		857	images).
		858
		859	This can be extremely useful to avoid redoing the same slow operations
		860	again and again- for example, if your background expression takes the root
		861	background, blurs it and then root-aligns it it would have to blur the
		862	root background on every window move or resize.
		863
		864	In fact, urxvt itself encloses the whole expression in some kind of
		865	C<once> block so it only is reevaluated as required.
		866
		867	Putting the blur into a C<once> block will make sure the blur is only done
		868	once:
		869
		870	rootlign once { blur 10, root }
		871
		872	This leaves the question of how to force reevaluation of the block,
		873	in case the root background changes: If expression inside the block
		874	is sensitive to some event (root background changes, window geometry
		875	changes), then it will be reevaluated automatically as needed.
		876
		877	=item once_again
		878
		879	Resets all C<once> block as if they had never been called, i.e. on the
		880	next call they will be reevaluated again.
		881
		882	=cut
		883
		884	sub once(&) {
		885	my $id = $_[0]+0;
		886
		887	local $frame = $self->{frame_cache}{$id} \|\|= [$frame];
		888
		889	unless ($frame->[FR_CACHE]) {
		890	$frame->[FR_CACHE] = [ $_[0]() ];
		891
		892	my $self = $self;
		893	my $frame = $frame;
		894	Scalar::Util::weaken $frame;
		895	$self->compile_frame ($frame, sub {
		896	# clear this frame cache, also for all parents
		897	for (my $frame = $frame; $frame; $frame = $frame->[0]) {
		898	undef $frame->[FR_CACHE];
		899	}
		900
		901	$self->recalculate;
		902	});
		903	};
		904
		905	# in scalar context we always return the first original result, which
		906	# is not quite how perl works.
		907	wantarray
		908	? @{ $frame->[FR_CACHE] }
		909	: $frame->[FR_CACHE][0]
		910	}
		911
		912	sub once_again() {
		913	delete $self->{frame_cache};
		914	}
		915
		916	=back
		917
690	=cut	918	=cut
691		919
692	}	920	}
693		921
694	sub parse_expr {	922	sub parse_expr {
695	my $expr = eval "sub {\npackage urxvt::bgdsl;\n#line 0 'background expression'\n$_[0]\n}";	923	my $expr = eval
		924	"sub {\n"
		925	. "package urxvt::bgdsl;\n"
		926	. "#line 0 'background expression'\n"
		927	. "$_[0]\n"
		928	. "}";
696	die if $@;	929	die if $@;
697	$expr	930	$expr
698	}	931	}
699		932
700	# compiles a parsed expression	933	# compiles a parsed expression
701	sub set_expr {	934	sub set_expr {
702	my ($self, $expr) = @_;	935	my ($self, $expr) = @_;
703		936
		937	$self->{root} = [];
704	$self->{expr} = $expr;	938	$self->{expr} = $expr;
705	$self->recalculate;	939	$self->recalculate;
		940	}
		941
		942	# takes a hash of sensitivity indicators and installs watchers
		943	sub compile_frame {
		944	my ($self, $frame, $cb) = @_;
		945
		946	my $state = $frame->[urxvt::bgdsl::FR_STATE] \|\|= {};
		947	my $again = $frame->[urxvt::bgdsl::FR_AGAIN];
		948
		949	# don't keep stuff alive
		950	Scalar::Util::weaken $state;
		951
		952	if ($again->{nested}) {
		953	$state->{nested} = 1;
		954	} else {
		955	delete $state->{nested};
		956	}
		957
		958	if (my $interval = $again->{time}) {
		959	$state->{time} = [$interval, urxvt::timer->new->after ($interval)->interval ($interval)]
		960	if $state->{time}[0] != $interval;
		961
		962	# callback might have changed, although we could just rule that out
		963	$state->{time}[1]->cb (sub {
		964	++$state->{counter};
		965	$cb->();
		966	});
		967	} else {
		968	delete $state->{time};
		969	}
		970
		971	if ($again->{position}) {
		972	$state->{position} = $self->on (position_change => $cb);
		973	} else {
		974	delete $state->{position};
		975	}
		976
		977	if ($again->{size}) {
		978	$state->{size} = $self->on (size_change => $cb);
		979	} else {
		980	delete $state->{size};
		981	}
		982
		983	if ($again->{rootpmap}) {
		984	$state->{rootpmap} = $self->on (rootpmap_change => $cb);
		985	} else {
		986	delete $state->{rootpmap};
		987	}
706	}	988	}
707		989
708	# evaluate the current bg expression	990	# evaluate the current bg expression
709	sub recalculate {	991	sub recalculate {
710	my ($arg_self) = @_;	992	my ($arg_self) = @_;
…		…
720		1002
721	$arg_self->{next_refresh} = urxvt::NOW + $MIN_INTERVAL;	1003	$arg_self->{next_refresh} = urxvt::NOW + $MIN_INTERVAL;
722		1004
723	# set environment to evaluate user expression	1005	# set environment to evaluate user expression
724		1006
725	local $self = $arg_self;	1007	local $self = $arg_self;
726
727	local $HOME = $ENV{HOME};	1008	local $HOME = $ENV{HOME};
728	local $old = $self->{state};	1009	local $frame = [];
729	local $new = my $state = $self->{state} = {};
730		1010
731	($x, $y, $w, $h) =
732	$self->background_geometry ($self->{border});	1011	($x, $y, $w, $h) = $self->background_geometry ($self->{border});
733		1012
734	# evaluate user expression	1013	# evaluate user expression
735		1014
736	my $img = eval { $self->{expr}->() };	1015	my @img = eval { $self->{expr}->() };
737	warn $@ if $@;#d#	1016	die $@ if $@;
		1017	die "background-expr did not return anything.\n" unless @img;
		1018	die "background-expr: expected image(s), got something else.\n"
738	die if !UNIVERSAL::isa $img, "urxvt::img";	1019	if grep { !UNIVERSAL::isa $_, "urxvt::img" } @img;
739		1020
740	$state->{size_sensitive} = 1	1021	my $img = urxvt::bgdsl::merge @img;
		1022
		1023	$frame->[FR_AGAIN]{size} = 1
741	if $img->repeat_mode != urxvt::RepeatNormal;	1024	if $img->repeat_mode != urxvt::RepeatNormal;
742		1025
743	# if the expression is sensitive to external events, prepare reevaluation then	1026	# if the expression is sensitive to external events, prepare reevaluation then
744		1027	$self->compile_frame ($frame, sub { $arg_self->recalculate });
745	my $repeat;
746
747	if (my $again = $state->{again}) {
748	$repeat = 1;
749	my $self = $self;
750	$state->{timer} = $again == $old->{again}
751	? $old->{timer}
752	: urxvt::timer->new->after ($again)->interval ($again)->cb (sub {
753	++$self->{counter};
754	$self->recalculate
755	});
756	}
757
758	if (delete $state->{position_sensitive}) {
759	$repeat = 1;
760	$self->enable (position_change => sub { $_[0]->recalculate });
761	} else {
762	$self->disable ("position_change");
763	}
764
765	if (delete $state->{size_sensitive}) {
766	$repeat = 1;
767	$self->enable (size_change => sub { $_[0]->recalculate });
768	} else {
769	$self->disable ("size_change");
770	}
771
772	if (delete $state->{rootpmap_sensitive}) {
773	$repeat = 1;
774	$self->enable (rootpmap_change => sub { $_[0]->recalculate });
775	} else {
776	$self->disable ("rootpmap_change");
777	}
778		1028
779	# clear stuff we no longer need	1029	# clear stuff we no longer need
780		1030
781	%$old = ();	1031	# unless (%{ $frame->[FR_STATE] }) {
782
783	unless ($repeat) {
784	delete $self->{state};	1032	# delete $self->{state};
785	delete $self->{expr};	1033	# delete $self->{expr};
786	}	1034	# }
787		1035
788	# set background pixmap	1036	# set background pixmap
789		1037
790	$self->set_background ($img, $self->{border});	1038	$self->set_background ($img, $self->{border});
791	$self->scr_recolour (0);	1039	$self->scr_recolour (0);
…		…
793	}	1041	}
794		1042
795	sub on_start {	1043	sub on_start {
796	my ($self) = @_;	1044	my ($self) = @_;
797		1045
798	my $expr = $self->x_resource ("background.expr")	1046	my $expr = $self->x_resource ("%.expr")
799	or return;	1047	or return;
800		1048
		1049	$self->has_render
		1050	or die "background extension needs RENDER extension 0.10 or higher, ignoring background-expr.\n";
		1051
801	$self->set_expr (parse_expr $expr);	1052	$self->set_expr (parse_expr $expr);
802	$self->{border} = $self->x_resource_boolean ("background.border");	1053	$self->{border} = $self->x_resource_boolean ("%.border");
		1054
		1055	$MIN_INTERVAL = $self->x_resource ("%.interval");
803		1056
804	()	1057	()
805	}	1058	}
806		1059

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Comparing rxvt-unicode/src/perl/background (file contents): Revision 1.44 by root, Sun Jun 10 11:31:22 2012 UTC vs. Revision 1.64 by root, Tue Jun 19 20:49:53 2012 UTC

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Comparing rxvt-unicode/src/perl/background (file contents):
Revision 1.44 by root, Sun Jun 10 11:31:22 2012 UTC vs.
Revision 1.64 by root, Tue Jun 19 20:49:53 2012 UTC