[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 1.68 by root, Sun Jul 1 21:47:07 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 inner expression is evaluated once per hour (and whenever the
		79	temrinal window is resized). It sets F<sunday.png> as background on
77	background on Sundays, and F<weekday.png> on all other days.	80	Sundays, and F<weekday.png> on all other days.
78		81
79	Fortunately, we expect that most expressions will be much simpler, with	82	Fortunately, we expect that most expressions will be much simpler, with
80	little Perl knowledge needed.	83	little Perl knowledge needed.
81		84
82	Basically, you always start with a function that "generates" an image	85	Basically, you always start with a function that "generates" an image
…		…
115	horizontal and vertical dimensions. For example, this halves the image	118	horizontal and vertical dimensions. For example, this halves the image
116	width and doubles the image height:	119	width and doubles the image height:
117		120
118	scale 0.5, 2, load "$HOME/mypic.png"	121	scale 0.5, 2, load "$HOME/mypic.png"
119		122
120	Other effects than scalign are also readily available, for exmaple, you can	123	IF you try out these expressions, you might suffer from some sluggishness,
121	tile the image to fill the whole window, instead of resizing it:	124	because each time the terminal is resized, it loads the PNG image agin
		125	and scales it. Scaling is usually fast (and unavoidable), but loading the
		126	image can be quite time consuming. This is where C<keep> comes in handy:
122		127
		128	scale 0.5, 2, keep { load "$HOME/mypic.png" }
		129
		130	The C<keep> operator executes all the statements inside the braces only
		131	once, or when it thinks the outcome might change. In other cases it
		132	returns the last value computed by the brace block.
		133
		134	This means that the C<load> is only executed once, which makes it much
		135	faster, but also means that more memory is being used, because the loaded
		136	image must be kept in memory at all times. In this expression, the
		137	trade-off is likely worth it.
		138
		139	But back to effects: Other effects than scaling are also readily
		140	available, for example, you can tile the image to fill the whole window,
		141	instead of resizing it:
		142
123	tile load "$HOME/mypic.png"	143	tile keep { load "$HOME/mypic.png" }
124		144
125	In fact, images returned by C<load> are in C<tile> mode by default, so the C<tile> operator	145	In fact, images returned by C<load> are in C<tile> mode by default, so the
126	is kind of superfluous.	146	C<tile> operator is kind of superfluous.
127		147
128	Another common effect is to mirror the image, so that the same edges touch:	148	Another common effect is to mirror the image, so that the same edges
		149	touch:
129		150
130	mirror load "$HOME/mypic.png"	151	mirror keep { load "$HOME/mypic.png" }
131		152
132	This is also a typical background expression:	153	Another common background expression is:
133		154
134	rootalign root	155	rootalign root
135		156
136	It first takes a snapshot of the screen background image, and then	157	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	158	moves it to the upper left corner of the screen (as opposed to the upper
138	pseudo-transparency, as the image seems to be static while the window is	159	left corner of the terminal window)- the result is pseudo-transparency:
139	moved around.	160	the image seems to be static while the window is moved around.
140		161
141	=head2 CYCLES AND CACHING	162	=head2 CACHING AND SENSITIVITY
142		163
143	As has been mentioned before, the expression might be evaluated multiple	164	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	165	caching results can be very important for a smooth operation. Caching can
145	have begun. Many operators cache their results till the next cycle.	166	also be useful to reduce memory usage, though, for example, when an image
		167	is cached by C<load>, it could be shared by multiple terminal windows
		168	running inside urxvtd.
146		169
147	For example, the C<load> operator keeps a copy of the image. If it is	170	=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		171
151	This only works for one cycle though, so as long as you load the same	172	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	173	... }>. The C<keep> operator takes a block of multiple statements enclosed
153	image, it will forget about the first one.	174	by C<{}> and keeps the return value in memory.
154		175
155	This allows you to either speed things up by keeping multiple images in	176	An expression can be "sensitive" to various external events, such as
156	memory, or comserve memory by loading images more often.	177	scaling or moving the window, root background changes and timers. Simply
		178	using an expression (such as C<scale> without parameters) that depends on
		179	certain changing values (called "variables"), or using those variables
		180	directly, will make an expression sensitive to these events - for example,
		181	using C<scale> or C<TW> will make the expression sensitive to the terminal
		182	size, and thus to resizing events.
157		183
158	For example, you can keep two images in memory and use a random one like	184	When such an event happens, C<keep> will automatically trigger a
159	this:	185	reevaluation of the whole expression with the new value of the expression.
160		186
161	my $img1 = load "img1.png";	187	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		188
165	Since both images are "loaded" every time the expression is evaluated,	189	rootalign keep { blur 20, root }
166	they are always kept in memory. Contrast this version:
167		190
168	my $path1 = "img1.png";	191	This makes a blurred copy of the root background once, and on subsequent
169	my $path2 = "img2.png";	192	calls, just root-aligns it. Since C<blur> is usually quite slow and
170	load ((0.5 > rand) ? $path1 : $path2)	193	C<rootalign> is quite fast, this trades extra memory (for the cached
		194	blurred pixmap) with speed (blur only needs to be redone when root
		195	changes).
171		196
172	Here, a path is selected randomly, and load is only called for one image,	197	=head3 C<load> caching
173	so keeps only one image in memory. If, on the next evaluation, luck	198
174	decides to use the other path, then it will have to load that image again.	199	The C<load> operator itself does not keep images in memory, but as long as
		200	the image is still in memory, C<load> will use the in-memory image instead
		201	of loading it freshly from disk.
		202
		203	That means that this expression:
		204
		205	keep { load "$HOME/path..." }
		206
		207	Not only caches the image in memory, other terminal instances that try to
		208	C<load> it can reuse that in-memory copy.
175		209
176	=head1 REFERENCE	210	=head1 REFERENCE
177		211
178	=head2 COMMAND LINE SWITCHES	212	=head2 COMMAND LINE SWITCHES
179		213
…		…
189	overwriting borders and any other areas, such as the scrollbar.	223	overwriting borders and any other areas, such as the scrollbar.
190		224
191	Specifying this flag changes the behaviour, so that the image only	225	Specifying this flag changes the behaviour, so that the image only
192	replaces the background of the character area.	226	replaces the background of the character area.
193		227
		228	=item --background-interval seconds
		229
		230	Since some operations in the underlying XRender extension can effectively
		231	freeze your X-server for prolonged time, this extension enforces a minimum
		232	time between updates, which is normally about 0.1 seconds.
		233
		234	If you want to do updates more often, you can decrease this safety
		235	interval with this switch.
		236
194	=back	237	=back
195		238
196	=cut	239	=cut
197		240
		241	our %_IMG_CACHE;
198	our $HOME;	242	our $HOME;
199	our ($self, $old, $new);	243	our ($self, $frame);
200	our ($x, $y, $w, $h);	244	our ($x, $y, $w, $h);
201		245
202	# enforce at least this interval between updates	246	# enforce at least this interval between updates
203	our $MIN_INTERVAL = 1/100;	247	our $MIN_INTERVAL = 6/59.951;
204		248
205	{	249	{
206	package urxvt::bgdsl; # background language	250	package urxvt::bgdsl; # background language
		251
		252	sub FR_PARENT() { 0 } # parent frame, if any - must be #0
		253	sub FR_CACHE () { 1 } # cached values
		254	sub FR_AGAIN () { 2 } # what this expr is sensitive to
		255	sub FR_STATE () { 3 } # watchers etc.
207		256
208	use List::Util qw(min max sum shuffle);	257	use List::Util qw(min max sum shuffle);
209		258
210	=head2 PROVIDERS/GENERATORS	259	=head2 PROVIDERS/GENERATORS
211		260
…		…
218	=item load $path	267	=item load $path
219		268
220	Loads the image at the given C<$path>. The image is set to plane tiling	269	Loads the image at the given C<$path>. The image is set to plane tiling
221	mode.	270	mode.
222		271
223	Loaded images will be cached for one cycle.	272	If the image is already in memory (e.g. because another terminal instance
		273	uses it), then the in-memory copy us returned instead.
224		274
		275	=item load_uc $path
		276
		277	Load uncached - same as load, but does not cache the image, which means it
		278	is I<always> loaded from the filesystem again.
		279
225	=cut	280	=cut
		281
		282	sub load_uc($) {
		283	$self->new_img_from_file ($path)
		284	}
226		285
227	sub load($) {	286	sub load($) {
228	my ($path) = @_;	287	my ($path) = @_;
229		288
230	$new->{load}{$path} = $old->{load}{$path} \|\| $self->new_img_from_file ($path);	289	$_IMG_CACHE{$path} \|\| do {
		290	my $img = load_uc $path;
		291	Scalar::Util::weaken ($_IMG_CACHE{$path} = $img);
		292	$img
		293	}
231	}	294	}
232		295
233	=item root	296	=item root
234		297
235	Returns the root window pixmap, that is, hopefully, the background image	298	Returns the root window pixmap, that is, hopefully, the background image
236	of your screen. The image is set to extend mode.	299	of your screen.
237		300
238	This function makes your expression root sensitive, that means it will be	301	This function makes your expression root sensitive, that means it will be
239	reevaluated when the bg image changes.	302	reevaluated when the bg image changes.
240		303
241	=cut	304	=cut
242		305
243	sub root() {	306	sub root() {
244	$new->{rootpmap_sensitive} = 1;	307	$frame->[FR_AGAIN]{rootpmap} = 1;
245	die "root op not supported, exg, we need you";	308	$self->new_img_from_root
246	}	309	}
247		310
248	=item solid $colour	311	=item solid $colour
249		312
250	=item solid $width, $height, $colour	313	=item solid $width, $height, $colour
…		…
258	=cut	321	=cut
259		322
260	sub solid($;$$) {	323	sub solid($;$$) {
261	my $colour = pop;	324	my $colour = pop;
262		325
263	my $img = $self->new_img (urxvt::PictStandardARGB32, $_[0] \|\| 1, $_[1] \|\| 1);	326	my $img = $self->new_img (urxvt::PictStandardARGB32, 0, 0, $_[0] \|\| 1, $_[1] \|\| 1);
264	$img->fill ($colour);	327	$img->fill ($colour);
265	$img	328	$img
266	}	329	}
267		330
268	=back	331	=item clone $img
269		332
270	=head2 VARIABLES	333	Returns an exact copy of the image. This is useful if you want to have
		334	multiple copies of the same image to apply different effects to.
271		335
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	336	=cut
314		337
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} = $_[0];
348	}
349
350	sub counter($) {	338	sub clone($) {
351	$new->{again} = $_[0];	339	$_[0]->clone
352	$self->{counter} + 0
353	}	340	}
354		341
355	=back	342	=item merge $img ...
		343
		344	Takes any number of images and merges them together, creating a single
		345	image containing them all. The tiling mode of the first image is used as
		346	the tiling mode of the resulting image.
		347
		348	This function is called automatically when an expression returns multiple
		349	images.
		350
		351	=cut
		352
		353	sub merge(@) {
		354	return $_[0] unless $#_;
		355
		356	# rather annoyingly clumsy, but optimisation is for another time
		357
		358	my $x0 = +1e9;
		359	my $y0 = +1e9;
		360	my $x1 = -1e9;
		361	my $y1 = -1e9;
		362
		363	for (@_) {
		364	my ($x, $y, $w, $h) = $_->geometry;
		365
		366	$x0 = $x if $x0 > $x;
		367	$y0 = $y if $y0 > $y;
		368
		369	$x += $w;
		370	$y += $h;
		371
		372	$x1 = $x if $x1 < $x;
		373	$y1 = $y if $y1 < $y;
		374	}
		375
		376	my $base = $self->new_img (urxvt::PictStandardARGB32, $x0, $y0, $x1 - $x0, $y1 - $y0);
		377	$base->repeat_mode ($_[0]->repeat_mode);
		378	$base->fill ([0, 0, 0, 0]);
		379
		380	$base->draw ($_)
		381	for @_;
		382
		383	$base
		384	}
356		385
357	=head2 TILING MODES	386	=head2 TILING MODES
358		387
359	The following operators modify the tiling mode of an image, that is, the	388	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.	389	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	419	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	420	image over another image or the background colour while leaving all
392	background pixels outside the image unchanged.	421	background pixels outside the image unchanged.
393		422
394	Example: load an image and display it in the upper left corner. The rest	423	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	424	of the space is left "empty" (transparent or whatever your compositor does
396	in alpha mode, else background colour).	425	in alpha mode, else background colour).
397		426
398	pad load "mybg.png"	427	pad load "mybg.png"
399		428
400	=item extend $img	429	=item extend $img
401		430
402	Extends the image over the whole plane, using the closest pixel in the	431	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	432	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	433	filtering operations and want the pixels outside the image to have the
405	same values as the pixels near the edge.	434	same values as the pixels near the edge.
406		435
407	Example: just for curiosity, how does this pixel extension stuff work?	436	Example: just for curiosity, how does this pixel extension stuff work?
408		437
…		…
434	$img	463	$img
435	}	464	}
436		465
437	=back	466	=back
438		467
439	=head2 PIXEL OPERATORS	468	=head2 VARIABLE VALUES
440		469
441	The following operators modify the image pixels in various ways.	470	The following functions provide variable data such as the terminal window
		471	dimensions. They are not (Perl-) variables, they just return stuff that
		472	varies. Most of them make your expression sensitive to some events, for
		473	example using C<TW> (terminal width) means your expression is evaluated
		474	again when the terminal is resized.
442		475
443	=over 4	476	=over 4
444		477
445	=item clone $img	478	=item TX
446		479
447	Returns an exact copy of the image.	480	=item TY
448		481
449	=cut	482	Return the X and Y coordinates of the terminal window (the terminal
		483	window is the full window by default, and the character area only when in
		484	border-respect mode).
450		485
		486	Using these functions make your expression sensitive to window moves.
		487
		488	These functions are mainly useful to align images to the root window.
		489
		490	Example: load an image and align it so it looks as if anchored to the
		491	background (that's exactly what C<rootalign> does btw.):
		492
		493	move -TX, -TY, keep { load "mybg.png" }
		494
		495	=item TW
		496
		497	Return the width (C<TW>) and height (C<TH>) of the terminal window (the
		498	terminal window is the full window by default, and the character area only
		499	when in border-respect mode).
		500
		501	Using these functions make your expression sensitive to window resizes.
		502
		503	These functions are mainly useful to scale images, or to clip images to
		504	the window size to conserve memory.
		505
		506	Example: take the screen background, clip it to the window size, blur it a
		507	bit, align it to the window position and use it as background.
		508
		509	clip move -TX, -TY, keep { blur 5, root }
		510
		511	=cut
		512
		513	sub TX() { $frame->[FR_AGAIN]{position} = 1; $x }
		514	sub TY() { $frame->[FR_AGAIN]{position} = 1; $y }
		515	sub TW() { $frame->[FR_AGAIN]{size} = 1; $w }
		516	sub TH() { $frame->[FR_AGAIN]{size} = 1; $h }
		517
		518	=item now
		519
		520	Returns the current time as (fractional) seconds since the epoch.
		521
		522	Using this expression does I<not> make your expression sensitive to time,
		523	but the next two functions do.
		524
		525	=item again $seconds
		526
		527	When this function is used the expression will be reevaluated again in
		528	C<$seconds> seconds.
		529
		530	Example: load some image and rotate it according to the time of day (as if it were
		531	the hour pointer of a clock). Update this image every minute.
		532
		533	again 60;
		534	rotate 50, 50, (now % 86400) * -72 / 8640, scale keep { load "myclock.png" }
		535
		536	=item counter $seconds
		537
		538	Like C<again>, but also returns an increasing counter value, starting at
		539	0, which might be useful for some simple animation effects.
		540
		541	=cut
		542
		543	sub now() { urxvt::NOW }
		544
		545	sub again($) {
		546	$frame->[FR_AGAIN]{time} = $_[0];
		547	}
		548
451	sub clone($) {	549	sub counter($) {
452	$_[0]->clone	550	$frame->[FR_AGAIN]{time} = $_[0];
		551	$frame->[FR_STATE]{counter} + 0
453	}	552	}
		553
		554	=back
		555
		556	=head2 SHAPE CHANGING OPERATORS
		557
		558	The following operators modify the shape, size or position of the image.
		559
		560	=over 4
454		561
455	=item clip $img	562	=item clip $img
456		563
457	=item clip $width, $height, $img	564	=item clip $width, $height, $img
458		565
…		…
469	assumed.	576	assumed.
470		577
471	Example: load an image, blur it, and clip it to the window size to save	578	Example: load an image, blur it, and clip it to the window size to save
472	memory.	579	memory.
473		580
474	clip blur 10, load "mybg.png"	581	clip keep { blur 10, load "mybg.png" }
475		582
476	=cut	583	=cut
477		584
478	sub clip($;$$;$$) {	585	sub clip($;$$;$$) {
479	my $img = pop;	586	my $img = pop;
…		…
552		659
553	Example: move the image right by 20 pixels and down by 30.	660	Example: move the image right by 20 pixels and down by 30.
554		661
555	move 20, 30, ...	662	move 20, 30, ...
556		663
		664	=item align $xalign, $yalign, $img
		665
		666	Aligns the image according to a factor - C<0> means the image is moved to
		667	the left or top edge (for C<$xalign> or C<$yalign>), C<0.5> means it is
		668	exactly centered and C<1> means it touches the right or bottom edge.
		669
		670	Example: remove any visible border around an image, center it vertically but move
		671	it to the right hand side.
		672
		673	align 1, 0.5, pad $img
		674
557	=item center $img	675	=item center $img
558		676
559	=item center $width, $height, $img	677	=item center $width, $height, $img
560		678
561	Centers the image, i.e. the center of the image is moved to the center of	679	Centers the image, i.e. the center of the image is moved to the center of
562	the terminal window (or the box specified by C<$width> and C<$height> if	680	the terminal window (or the box specified by C<$width> and C<$height> if
563	given).	681	given).
		682
		683	Example: load an image and center it.
		684
		685	center keep { pad load "mybg.png" }
564		686
565	=item rootalign $img	687	=item rootalign $img
566		688
567	Moves the image so that it appears glued to the screen as opposed to the	689	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	690	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	691	exactly equivalent to C<move -TX, -TY>, that is, it moves the image to the
570	top left of the screen.	692	top left of the screen.
571		693
572	Example: load a background image, put it in mirror mode and root align it.	694	Example: load a background image, put it in mirror mode and root align it.
573		695
574	rootalign mirror load "mybg.png"	696	rootalign keep { mirror load "mybg.png" }
575		697
576	Example: take the screen background and align it, giving the illusion of	698	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.	699	transparency as long as the window isn't in front of other windows.
578		700
579	rootalign root	701	rootalign root
580		702
581	=cut	703	=cut
582		704
583	sub move($$;$) {	705	sub move($$;$) {
584	my $img = pop->clone;	706	my $img = pop->clone;
585	$img->move ($_[0], $_[1]);	707	$img->move ($_[0], $_[1]);
586	$img	708	$img
587	}	709	}
588		710
		711	sub align($;$$) {
		712	my $img = pop;
		713
		714	move $_[0] * (TW - $img->w),
		715	$_[1] * (TH - $img->h),
		716	$img
		717	}
		718
589	sub center($;$$) {	719	sub center($;$$) {
590	my $img = pop;	720	my $img = pop;
591	my $w = $_[0] \|\| TW;	721	my $w = $_[0] \|\| TW;
592	my $h = $_[0] \|\| TH;	722	my $h = $_[1] \|\| TH;
593		723
594	move 0.5 * ($w - $img->w), 0.5 * ($h - $img->h), $img	724	move 0.5 * ($w - $img->w), 0.5 * ($h - $img->h), $img
595	}	725	}
596		726
597	sub rootalign($) {	727	sub rootalign($) {
598	move -TX, -TY, $_[0]	728	move -TX, -TY, $_[0]
599	}	729	}
600		730
		731	=item rotate $center_x, $center_y, $degrees, $img
		732
		733	Rotates the image clockwise by C<$degrees> degrees, around the point at
		734	C<$center_x> and C<$center_y> (specified as factor of image width/height).
		735
		736	Example: rotate the image by 90 degrees around it's center.
		737
		738	rotate 0.5, 0.5, 90, keep { load "$HOME/mybg.png" }
		739
		740	=cut
		741
		742	sub rotate($$$$) {
		743	my $img = pop;
		744	$img->rotate (
		745	$_[0] * ($img->w + $img->x),
		746	$_[1] * ($img->h + $img->y),
		747	$_[2] * (3.14159265 / 180),
		748	)
		749	}
		750
		751	=back
		752
		753	=head2 COLOUR MODIFICATIONS
		754
		755	The following operators change the pixels of the image.
		756
		757	=over 4
		758
601	=item contrast $factor, $img	759	=item contrast $factor, $img
602		760
603	=item contrast $r, $g, $b, $img	761	=item contrast $r, $g, $b, $img
604		762
605	=item contrast $r, $g, $b, $a, $img	763	=item contrast $r, $g, $b, $a, $img
606		764
607	Adjusts the I<contrast> of an image.	765	Adjusts the I<contrast> of an image.
608		766
609	#TODO#	767	The first form applies a single C<$factor> to red, green and blue, the
		768	second form applies separate factors to each colour channel, and the last
		769	form includes the alpha channel.
610		770
		771	Values from 0 to 1 lower the contrast, values higher than 1 increase the
		772	contrast.
		773
		774	Due to limitations in the underlying XRender extension, lowering contrast
		775	also reduces brightness, while increasing contrast currently also
		776	increases brightness.
		777
611	=item brightness $factor, $img	778	=item brightness $bias, $img
612		779
613	=item brightness $r, $g, $b, $img	780	=item brightness $r, $g, $b, $img
614		781
615	=item brightness $r, $g, $b, $a, $img	782	=item brightness $r, $g, $b, $a, $img
616		783
617	Adjusts the brightness of an image.	784	Adjusts the brightness of an image.
		785
		786	The first form applies a single C<$bias> to red, green and blue, the
		787	second form applies separate biases to each colour channel, and the last
		788	form includes the alpha channel.
		789
		790	Values less than 0 reduce brightness, while values larger than 0 increase
		791	it. Useful range is from -1 to 1 - the former results in a black, the
		792	latter in a white picture.
		793
		794	Due to idiosyncrasies in the underlying XRender extension, biases less
		795	than zero can be I<very> slow.
618		796
619	=cut	797	=cut
620		798
621	sub contrast($$;$$;$) {	799	sub contrast($$;$$;$) {
622	my $img = pop;	800	my $img = pop;
623	my ($r, $g, $b, $a) = @_;	801	my ($r, $g, $b, $a) = @_;
624		802
625	($g, $b) = ($r, $r) if @_ < 4;	803	($g, $b) = ($r, $r) if @_ < 3;
626	$a = 1 if @_ < 5;	804	$a = 1 if @_ < 4;
627		805
628	$img = $img->clone;	806	$img = $img->clone;
629	$img->contrast ($r, $g, $b, $a);	807	$img->contrast ($r, $g, $b, $a);
630	$img	808	$img
631	}	809	}
632		810
633	sub brightness($$;$$;$) {	811	sub brightness($$;$$;$) {
634	my $img = pop;	812	my $img = pop;
635	my ($r, $g, $b, $a) = @_;	813	my ($r, $g, $b, $a) = @_;
636		814
637	($g, $b) = ($r, $r) if @_ < 4;	815	($g, $b) = ($r, $r) if @_ < 3;
638	$a = 1 if @_ < 5;	816	$a = 1 if @_ < 4;
639		817
640	$img = $img->clone;	818	$img = $img->clone;
641	$img->brightness ($r, $g, $b, $a);	819	$img->brightness ($r, $g, $b, $a);
642	$img	820	$img
643	}	821	}
…		…
659	sub blur($$;$) {	837	sub blur($$;$) {
660	my $img = pop;	838	my $img = pop;
661	$img->blur ($_[0], @_ >= 2 ? $_[1] : $_[0])	839	$img->blur ($_[0], @_ >= 2 ? $_[1] : $_[0])
662	}	840	}
663		841
664	=item rotate $new_width, $new_height, $center_x, $center_y, $degrees
665
666	Rotates the image by C<$degrees> degrees, counter-clockwise, around the
667	pointer at C<$center_x> and C<$center_y> (specified as factor of image
668	width/height), generating a new image with width C<$new_width> and height
669	C<$new_height>.
670
671	#TODO# new width, height, maybe more operators?
672
673	Example: rotate the image by 90 degrees
674
675	=cut
676
677	sub rotate($$$$$$) {
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	842	=back
689		843
		844	=head2 OTHER STUFF
		845
		846	Anything that didn't fit any of the other categories, even after applying
		847	force and closing our eyes.
		848
		849	=over 4
		850
		851	=item keep { ... }
		852
		853	This operator takes a code block as argument, that is, one or more
		854	statements enclosed by braces.
		855
		856	The trick is that this code block is only evaluated when the outcome
		857	changes - on other calls the C<keep> simply returns the image it computed
		858	previously (yes, it should only be used with images). Or in other words,
		859	C<keep> I<caches> the result of the code block so it doesn't need to be
		860	computed again.
		861
		862	This can be extremely useful to avoid redoing slow operations - for
		863	example, if your background expression takes the root background, blurs it
		864	and then root-aligns it it would have to blur the root background on every
		865	window move or resize.
		866
		867	Another example is C<load>, which can be quite slow.
		868
		869	In fact, urxvt itself encloses the whole expression in some kind of
		870	C<keep> block so it only is reevaluated as required.
		871
		872	Putting the blur into a C<keep> block will make sure the blur is only done
		873	once, while the C<rootalign> is still done each time the window moves.
		874
		875	rootlign keep { blur 10, root }
		876
		877	This leaves the question of how to force reevaluation of the block,
		878	in case the root background changes: If expression inside the block
		879	is sensitive to some event (root background changes, window geometry
		880	changes), then it will be reevaluated automatically as needed.
		881
		882	=cut
		883
		884	sub keep(&) {
		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 keep_clear() {
		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 1.68 by root, Sun Jul 1 21:47:07 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 1.68 by root, Sun Jul 1 21:47:07 2012 UTC