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

Comparing rxvt-unicode/src/perl/background (file contents):
Revision 1.43 by root, Sun Jun 10 11:23:20 2012 UTC vs.
Revision 1.69 by root, Mon Jul 2 01:32:26 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.
		274
		275	=item load_uc $path
		276
		277	Load uncached - same as load, but does not cache the image, which means it
		278	is I<always> loaded from the filesystem again.
224		279
225	=cut	280	=cut
226		281
227	sub load($) {	282	sub load($) {
228	my ($path) = @_;	283	my ($path) = @_;
229		284
230	$new->{load}{$path} = $old->{load}{$path} \|\| $self->new_img_from_file ($path);	285	$_IMG_CACHE{$path} \|\| do {
		286	my $img = $self->new_img_from_file ($path);
		287	Scalar::Util::weaken ($_IMG_CACHE{$path} = $img);
		288	$img
		289	}
231	}	290	}
232		291
233	=item root	292	=item root
234		293
235	Returns the root window pixmap, that is, hopefully, the background image	294	Returns the root window pixmap, that is, hopefully, the background image
236	of your screen. The image is set to extend mode.	295	of your screen.
237		296
238	This function makes your expression root sensitive, that means it will be	297	This function makes your expression root sensitive, that means it will be
239	reevaluated when the bg image changes.	298	reevaluated when the bg image changes.
240		299
241	=cut	300	=cut
242		301
243	sub root() {	302	sub root() {
244	$new->{rootpmap_sensitive} = 1;	303	$frame->[FR_AGAIN]{rootpmap} = 1;
245	die "root op not supported, exg, we need you";	304	$self->new_img_from_root
246	}	305	}
247		306
248	=item solid $colour	307	=item solid $colour
249		308
250	=item solid $width, $height, $colour	309	=item solid $width, $height, $colour
…		…
258	=cut	317	=cut
259		318
260	sub solid($;$$) {	319	sub solid($;$$) {
261	my $colour = pop;	320	my $colour = pop;
262		321
263	my $img = $self->new_img (urxvt::PictStandardARGB32, $_[0] \|\| 1, $_[1] \|\| 1);	322	my $img = $self->new_img (urxvt::PictStandardARGB32, 0, 0, $_[0] \|\| 1, $_[1] \|\| 1);
264	$img->fill ($colour);	323	$img->fill ($colour);
265	$img	324	$img
266	}	325	}
267		326
268	=back	327	=item clone $img
269		328
270	=head2 VARIABLES	329	Returns an exact copy of the image. This is useful if you want to have
		330	multiple copies of the same image to apply different effects to.
271		331
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	332	=cut
314		333
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} = $_[0];
348	}
349
350	sub counter($) {	334	sub clone($) {
351	$new->{again} = $_[0];	335	$_[0]->clone
352	$self->{counter} + 0
353	}	336	}
354		337
355	=back	338	=item merge $img ...
		339
		340	Takes any number of images and merges them together, creating a single
		341	image containing them all. The tiling mode of the first image is used as
		342	the tiling mode of the resulting image.
		343
		344	This function is called automatically when an expression returns multiple
		345	images.
		346
		347	=cut
		348
		349	sub merge(@) {
		350	return $_[0] unless $#_;
		351
		352	# rather annoyingly clumsy, but optimisation is for another time
		353
		354	my $x0 = +1e9;
		355	my $y0 = +1e9;
		356	my $x1 = -1e9;
		357	my $y1 = -1e9;
		358
		359	for (@_) {
		360	my ($x, $y, $w, $h) = $_->geometry;
		361
		362	$x0 = $x if $x0 > $x;
		363	$y0 = $y if $y0 > $y;
		364
		365	$x += $w;
		366	$y += $h;
		367
		368	$x1 = $x if $x1 < $x;
		369	$y1 = $y if $y1 < $y;
		370	}
		371
		372	my $base = $self->new_img (urxvt::PictStandardARGB32, $x0, $y0, $x1 - $x0, $y1 - $y0);
		373	$base->repeat_mode ($_[0]->repeat_mode);
		374	$base->fill ([0, 0, 0, 0]);
		375
		376	$base->draw ($_)
		377	for @_;
		378
		379	$base
		380	}
356		381
357	=head2 TILING MODES	382	=head2 TILING MODES
358		383
359	The following operators modify the tiling mode of an image, that is, the	384	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.	385	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	415	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	416	image over another image or the background colour while leaving all
392	background pixels outside the image unchanged.	417	background pixels outside the image unchanged.
393		418
394	Example: load an image and display it in the upper left corner. The rest	419	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	420	of the space is left "empty" (transparent or whatever your compositor does
396	in alpha mode, else background colour).	421	in alpha mode, else background colour).
397		422
398	pad load "mybg.png"	423	pad load "mybg.png"
399		424
400	=item extend $img	425	=item extend $img
401		426
402	Extends the image over the whole plane, using the closest pixel in the	427	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	428	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	429	filtering operations and want the pixels outside the image to have the
405	same values as the pixels near the edge.	430	same values as the pixels near the edge.
406		431
407	Example: just for curiosity, how does this pixel extension stuff work?	432	Example: just for curiosity, how does this pixel extension stuff work?
408		433
…		…
434	$img	459	$img
435	}	460	}
436		461
437	=back	462	=back
438		463
439	=head2 PIXEL OPERATORS	464	=head2 VARIABLE VALUES
440		465
441	The following operators modify the image pixels in various ways.	466	The following functions provide variable data such as the terminal window
		467	dimensions. They are not (Perl-) variables, they just return stuff that
		468	varies. Most of them make your expression sensitive to some events, for
		469	example using C<TW> (terminal width) means your expression is evaluated
		470	again when the terminal is resized.
442		471
443	=over 4	472	=over 4
444		473
445	=item clone $img	474	=item TX
446		475
447	Returns an exact copy of the image.	476	=item TY
448		477
449	=cut	478	Return the X and Y coordinates of the terminal window (the terminal
		479	window is the full window by default, and the character area only when in
		480	border-respect mode).
450		481
		482	Using these functions make your expression sensitive to window moves.
		483
		484	These functions are mainly useful to align images to the root window.
		485
		486	Example: load an image and align it so it looks as if anchored to the
		487	background (that's exactly what C<rootalign> does btw.):
		488
		489	move -TX, -TY, keep { load "mybg.png" }
		490
		491	=item TW
		492
		493	Return the width (C<TW>) and height (C<TH>) of the terminal window (the
		494	terminal window is the full window by default, and the character area only
		495	when in border-respect mode).
		496
		497	Using these functions make your expression sensitive to window resizes.
		498
		499	These functions are mainly useful to scale images, or to clip images to
		500	the window size to conserve memory.
		501
		502	Example: take the screen background, clip it to the window size, blur it a
		503	bit, align it to the window position and use it as background.
		504
		505	clip move -TX, -TY, keep { blur 5, root }
		506
		507	=cut
		508
		509	sub TX() { $frame->[FR_AGAIN]{position} = 1; $x }
		510	sub TY() { $frame->[FR_AGAIN]{position} = 1; $y }
		511	sub TW() { $frame->[FR_AGAIN]{size} = 1; $w }
		512	sub TH() { $frame->[FR_AGAIN]{size} = 1; $h }
		513
		514	=item now
		515
		516	Returns the current time as (fractional) seconds since the epoch.
		517
		518	Using this expression does I<not> make your expression sensitive to time,
		519	but the next two functions do.
		520
		521	=item again $seconds
		522
		523	When this function is used the expression will be reevaluated again in
		524	C<$seconds> seconds.
		525
		526	Example: load some image and rotate it according to the time of day (as if it were
		527	the hour pointer of a clock). Update this image every minute.
		528
		529	again 60;
		530	rotate 50, 50, (now % 86400) * -72 / 8640, scale keep { load "myclock.png" }
		531
		532	=item counter $seconds
		533
		534	Like C<again>, but also returns an increasing counter value, starting at
		535	0, which might be useful for some simple animation effects.
		536
		537	=cut
		538
		539	sub now() { urxvt::NOW }
		540
		541	sub again($) {
		542	$frame->[FR_AGAIN]{time} = $_[0];
		543	}
		544
451	sub clone($) {	545	sub counter($) {
452	$_[0]->clone	546	$frame->[FR_AGAIN]{time} = $_[0];
		547	$frame->[FR_STATE]{counter} + 0
453	}	548	}
		549
		550	=back
		551
		552	=head2 SHAPE CHANGING OPERATORS
		553
		554	The following operators modify the shape, size or position of the image.
		555
		556	=over 4
454		557
455	=item clip $img	558	=item clip $img
456		559
457	=item clip $width, $height, $img	560	=item clip $width, $height, $img
458		561
…		…
469	assumed.	572	assumed.
470		573
471	Example: load an image, blur it, and clip it to the window size to save	574	Example: load an image, blur it, and clip it to the window size to save
472	memory.	575	memory.
473		576
474	clip blur 10, load "mybg.png"	577	clip keep { blur 10, load "mybg.png" }
475		578
476	=cut	579	=cut
477		580
478	sub clip($;$$;$$) {	581	sub clip($;$$;$$) {
479	my $img = pop;	582	my $img = pop;
…		…
552		655
553	Example: move the image right by 20 pixels and down by 30.	656	Example: move the image right by 20 pixels and down by 30.
554		657
555	move 20, 30, ...	658	move 20, 30, ...
556		659
		660	=item align $xalign, $yalign, $img
		661
		662	Aligns the image according to a factor - C<0> means the image is moved to
		663	the left or top edge (for C<$xalign> or C<$yalign>), C<0.5> means it is
		664	exactly centered and C<1> means it touches the right or bottom edge.
		665
		666	Example: remove any visible border around an image, center it vertically but move
		667	it to the right hand side.
		668
		669	align 1, 0.5, pad $img
		670
		671	=item center $img
		672
		673	=item center $width, $height, $img
		674
		675	Centers the image, i.e. the center of the image is moved to the center of
		676	the terminal window (or the box specified by C<$width> and C<$height> if
		677	given).
		678
		679	Example: load an image and center it.
		680
		681	center keep { pad load "mybg.png" }
		682
557	=item rootalign $img	683	=item rootalign $img
558		684
559	Moves the image so that it appears glued to the screen as opposed to the	685	Moves the image so that it appears glued to the screen as opposed to the
560	window. This gives the illusion of a larger area behind the window. It is	686	window. This gives the illusion of a larger area behind the window. It is
561	exactly equivalent to C<move -TX, -TY>, that is, it moves the image to the	687	exactly equivalent to C<move -TX, -TY>, that is, it moves the image to the
562	top left of the screen.	688	top left of the screen.
563		689
564	Example: load a background image, put it in mirror mode and root align it.	690	Example: load a background image, put it in mirror mode and root align it.
565		691
566	rootalign mirror load "mybg.png"	692	rootalign keep { mirror load "mybg.png" }
567		693
568	Example: take the screen background and align it, giving the illusion of	694	Example: take the screen background and align it, giving the illusion of
569	transparency as long as the window isn't in front of other windows.	695	transparency as long as the window isn't in front of other windows.
570		696
571	rootalign root	697	rootalign root
572		698
573	=cut	699	=cut
574		700
575	sub move($$;$) {	701	sub move($$;$) {
576	my $img = pop->clone;	702	my $img = pop->clone;
577	$img->move ($_[0], $_[1]);	703	$img->move ($_[0], $_[1]);
578	$img	704	$img
579	}	705	}
580		706
		707	sub align($;$$) {
		708	my $img = pop;
		709
		710	move $_[0] * (TW - $img->w),
		711	$_[1] * (TH - $img->h),
		712	$img
		713	}
		714
		715	sub center($;$$) {
		716	my $img = pop;
		717	my $w = $_[0] \|\| TW;
		718	my $h = $_[1] \|\| TH;
		719
		720	move 0.5 * ($w - $img->w), 0.5 * ($h - $img->h), $img
		721	}
		722
581	sub rootalign($) {	723	sub rootalign($) {
582	move -TX, -TY, $_[0]	724	move -TX, -TY, $_[0]
583	}	725	}
584		726
		727	=item rotate $center_x, $center_y, $degrees, $img
		728
		729	Rotates the image clockwise by C<$degrees> degrees, around the point at
		730	C<$center_x> and C<$center_y> (specified as factor of image width/height).
		731
		732	Example: rotate the image by 90 degrees around it's center.
		733
		734	rotate 0.5, 0.5, 90, keep { load "$HOME/mybg.png" }
		735
		736	=cut
		737
		738	sub rotate($$$$) {
		739	my $img = pop;
		740	$img->rotate (
		741	$_[0] * ($img->w + $img->x),
		742	$_[1] * ($img->h + $img->y),
		743	$_[2] * (3.14159265 / 180),
		744	)
		745	}
		746
		747	=back
		748
		749	=head2 COLOUR MODIFICATIONS
		750
		751	The following operators change the pixels of the image.
		752
		753	=over 4
		754
585	=item contrast $factor, $img	755	=item contrast $factor, $img
586		756
587	=item contrast $r, $g, $b, $img	757	=item contrast $r, $g, $b, $img
588		758
589	=item contrast $r, $g, $b, $a, $img	759	=item contrast $r, $g, $b, $a, $img
590		760
591	Adjusts the I<contrast> of an image.	761	Adjusts the I<contrast> of an image.
592		762
593	#TODO#	763	The first form applies a single C<$factor> to red, green and blue, the
		764	second form applies separate factors to each colour channel, and the last
		765	form includes the alpha channel.
594		766
		767	Values from 0 to 1 lower the contrast, values higher than 1 increase the
		768	contrast.
		769
		770	Due to limitations in the underlying XRender extension, lowering contrast
		771	also reduces brightness, while increasing contrast currently also
		772	increases brightness.
		773
595	=item brightness $factor, $img	774	=item brightness $bias, $img
596		775
597	=item brightness $r, $g, $b, $img	776	=item brightness $r, $g, $b, $img
598		777
599	=item brightness $r, $g, $b, $a, $img	778	=item brightness $r, $g, $b, $a, $img
600		779
601	Adjusts the brightness of an image.	780	Adjusts the brightness of an image.
		781
		782	The first form applies a single C<$bias> to red, green and blue, the
		783	second form applies separate biases to each colour channel, and the last
		784	form includes the alpha channel.
		785
		786	Values less than 0 reduce brightness, while values larger than 0 increase
		787	it. Useful range is from -1 to 1 - the former results in a black, the
		788	latter in a white picture.
		789
		790	Due to idiosyncrasies in the underlying XRender extension, biases less
		791	than zero can be I<very> slow.
602		792
603	=cut	793	=cut
604		794
605	sub contrast($$;$$;$) {	795	sub contrast($$;$$;$) {
606	my $img = pop;	796	my $img = pop;
607	my ($r, $g, $b, $a) = @_;	797	my ($r, $g, $b, $a) = @_;
608		798
609	($g, $b) = ($r, $r) if @_ < 4;	799	($g, $b) = ($r, $r) if @_ < 3;
610	$a = 1 if @_ < 5;	800	$a = 1 if @_ < 4;
611		801
612	$img = $img->clone;	802	$img = $img->clone;
613	$img->contrast ($r, $g, $b, $a);	803	$img->contrast ($r, $g, $b, $a);
614	$img	804	$img
615	}	805	}
616		806
617	sub brightness($$;$$;$) {	807	sub brightness($$;$$;$) {
618	my $img = pop;	808	my $img = pop;
619	my ($r, $g, $b, $a) = @_;	809	my ($r, $g, $b, $a) = @_;
620		810
621	($g, $b) = ($r, $r) if @_ < 4;	811	($g, $b) = ($r, $r) if @_ < 3;
622	$a = 1 if @_ < 5;	812	$a = 1 if @_ < 4;
623		813
624	$img = $img->clone;	814	$img = $img->clone;
625	$img->brightness ($r, $g, $b, $a);	815	$img->brightness ($r, $g, $b, $a);
626	$img	816	$img
627	}	817	}
…		…
643	sub blur($$;$) {	833	sub blur($$;$) {
644	my $img = pop;	834	my $img = pop;
645	$img->blur ($_[0], @_ >= 2 ? $_[1] : $_[0])	835	$img->blur ($_[0], @_ >= 2 ? $_[1] : $_[0])
646	}	836	}
647		837
648	=item rotate $new_width, $new_height, $center_x, $center_y, $degrees
649
650	Rotates the image by C<$degrees> degrees, counter-clockwise, around the
651	pointer at C<$center_x> and C<$center_y> (specified as factor of image
652	width/height), generating a new image with width C<$new_width> and height
653	C<$new_height>.
654
655	#TODO# new width, height, maybe more operators?
656
657	Example: rotate the image by 90 degrees
658
659	=cut
660
661	sub rotate($$$$$$) {
662	my $img = pop;
663	$img->rotate (
664	$_[0],
665	$_[1],
666	$_[2] * $img->w,
667	$_[3] * $img->h,
668	$_[4] * (3.14159265 / 180),
669	)
670	}
671
672	=back	838	=back
673		839
		840	=head2 OTHER STUFF
		841
		842	Anything that didn't fit any of the other categories, even after applying
		843	force and closing our eyes.
		844
		845	=over 4
		846
		847	=item keep { ... }
		848
		849	This operator takes a code block as argument, that is, one or more
		850	statements enclosed by braces.
		851
		852	The trick is that this code block is only evaluated when the outcome
		853	changes - on other calls the C<keep> simply returns the image it computed
		854	previously (yes, it should only be used with images). Or in other words,
		855	C<keep> I<caches> the result of the code block so it doesn't need to be
		856	computed again.
		857
		858	This can be extremely useful to avoid redoing slow operations - for
		859	example, if your background expression takes the root background, blurs it
		860	and then root-aligns it it would have to blur the root background on every
		861	window move or resize.
		862
		863	Another example is C<load>, which can be quite slow.
		864
		865	In fact, urxvt itself encloses the whole expression in some kind of
		866	C<keep> block so it only is reevaluated as required.
		867
		868	Putting the blur into a C<keep> block will make sure the blur is only done
		869	once, while the C<rootalign> is still done each time the window moves.
		870
		871	rootlign keep { blur 10, root }
		872
		873	This leaves the question of how to force reevaluation of the block,
		874	in case the root background changes: If expression inside the block
		875	is sensitive to some event (root background changes, window geometry
		876	changes), then it will be reevaluated automatically as needed.
		877
		878	=cut
		879
		880	sub keep(&) {
		881	my $id = $_[0]+0;
		882
		883	local $frame = $self->{frame_cache}{$id} \|\|= [$frame];
		884
		885	unless ($frame->[FR_CACHE]) {
		886	$frame->[FR_CACHE] = [ $_[0]() ];
		887
		888	my $self = $self;
		889	my $frame = $frame;
		890	Scalar::Util::weaken $frame;
		891	$self->compile_frame ($frame, sub {
		892	# clear this frame cache, also for all parents
		893	for (my $frame = $frame; $frame; $frame = $frame->[0]) {
		894	undef $frame->[FR_CACHE];
		895	}
		896
		897	$self->recalculate;
		898	});
		899	};
		900
		901	# in scalar context we always return the first original result, which
		902	# is not quite how perl works.
		903	wantarray
		904	? @{ $frame->[FR_CACHE] }
		905	: $frame->[FR_CACHE][0]
		906	}
		907
		908	# sub keep_clear() {
		909	# delete $self->{frame_cache};
		910	# }
		911
		912	=back
		913
674	=cut	914	=cut
675		915
676	}	916	}
677		917
678	sub parse_expr {	918	sub parse_expr {
679	my $expr = eval "sub {\npackage urxvt::bgdsl;\n#line 0 'background expression'\n$_[0]\n}";	919	my $expr = eval
		920	"sub {\n"
		921	. "package urxvt::bgdsl;\n"
		922	. "#line 0 'background expression'\n"
		923	. "$_[0]\n"
		924	. "}";
680	die if $@;	925	die if $@;
681	$expr	926	$expr
682	}	927	}
683		928
684	# compiles a parsed expression	929	# compiles a parsed expression
685	sub set_expr {	930	sub set_expr {
686	my ($self, $expr) = @_;	931	my ($self, $expr) = @_;
687		932
		933	$self->{root} = [];
688	$self->{expr} = $expr;	934	$self->{expr} = $expr;
689	$self->recalculate;	935	$self->recalculate;
		936	}
		937
		938	# takes a hash of sensitivity indicators and installs watchers
		939	sub compile_frame {
		940	my ($self, $frame, $cb) = @_;
		941
		942	my $state = $frame->[urxvt::bgdsl::FR_STATE] \|\|= {};
		943	my $again = $frame->[urxvt::bgdsl::FR_AGAIN];
		944
		945	# don't keep stuff alive
		946	Scalar::Util::weaken $state;
		947
		948	if ($again->{nested}) {
		949	$state->{nested} = 1;
		950	} else {
		951	delete $state->{nested};
		952	}
		953
		954	if (my $interval = $again->{time}) {
		955	$state->{time} = [$interval, urxvt::timer->new->after ($interval)->interval ($interval)]
		956	if $state->{time}[0] != $interval;
		957
		958	# callback might have changed, although we could just rule that out
		959	$state->{time}[1]->cb (sub {
		960	++$state->{counter};
		961	$cb->();
		962	});
		963	} else {
		964	delete $state->{time};
		965	}
		966
		967	if ($again->{position}) {
		968	$state->{position} = $self->on (position_change => $cb);
		969	} else {
		970	delete $state->{position};
		971	}
		972
		973	if ($again->{size}) {
		974	$state->{size} = $self->on (size_change => $cb);
		975	} else {
		976	delete $state->{size};
		977	}
		978
		979	if ($again->{rootpmap}) {
		980	$state->{rootpmap} = $self->on (rootpmap_change => $cb);
		981	} else {
		982	delete $state->{rootpmap};
		983	}
690	}	984	}
691		985
692	# evaluate the current bg expression	986	# evaluate the current bg expression
693	sub recalculate {	987	sub recalculate {
694	my ($arg_self) = @_;	988	my ($arg_self) = @_;
…		…
704		998
705	$arg_self->{next_refresh} = urxvt::NOW + $MIN_INTERVAL;	999	$arg_self->{next_refresh} = urxvt::NOW + $MIN_INTERVAL;
706		1000
707	# set environment to evaluate user expression	1001	# set environment to evaluate user expression
708		1002
709	local $self = $arg_self;	1003	local $self = $arg_self;
710
711	local $HOME = $ENV{HOME};	1004	local $HOME = $ENV{HOME};
712	local $old = $self->{state};	1005	local $frame = [];
713	local $new = my $state = $self->{state} = {};
714		1006
715	($x, $y, $w, $h) =
716	$self->background_geometry ($self->{border});	1007	($x, $y, $w, $h) = $self->background_geometry ($self->{border});
717		1008
718	# evaluate user expression	1009	# evaluate user expression
719		1010
720	my $img = eval { $self->{expr}->() };	1011	my @img = eval { $self->{expr}->() };
721	warn $@ if $@;#d#	1012	die $@ if $@;
		1013	die "background-expr did not return anything.\n" unless @img;
		1014	die "background-expr: expected image(s), got something else.\n"
722	die if !UNIVERSAL::isa $img, "urxvt::img";	1015	if grep { !UNIVERSAL::isa $_, "urxvt::img" } @img;
723		1016
724	$state->{size_sensitive} = 1	1017	my $img = urxvt::bgdsl::merge @img;
		1018
		1019	$frame->[FR_AGAIN]{size} = 1
725	if $img->repeat_mode != urxvt::RepeatNormal;	1020	if $img->repeat_mode != urxvt::RepeatNormal;
726		1021
727	# if the expression is sensitive to external events, prepare reevaluation then	1022	# if the expression is sensitive to external events, prepare reevaluation then
728		1023	$self->compile_frame ($frame, sub { $arg_self->recalculate });
729	my $repeat;
730
731	if (my $again = $state->{again}) {
732	$repeat = 1;
733	my $self = $self;
734	$state->{timer} = $again == $old->{again}
735	? $old->{timer}
736	: urxvt::timer->new->after ($again)->interval ($again)->cb (sub {
737	++$self->{counter};
738	$self->recalculate
739	});
740	}
741
742	if (delete $state->{position_sensitive}) {
743	$repeat = 1;
744	$self->enable (position_change => sub { $_[0]->recalculate });
745	} else {
746	$self->disable ("position_change");
747	}
748
749	if (delete $state->{size_sensitive}) {
750	$repeat = 1;
751	$self->enable (size_change => sub { $_[0]->recalculate });
752	} else {
753	$self->disable ("size_change");
754	}
755
756	if (delete $state->{rootpmap_sensitive}) {
757	$repeat = 1;
758	$self->enable (rootpmap_change => sub { $_[0]->recalculate });
759	} else {
760	$self->disable ("rootpmap_change");
761	}
762		1024
763	# clear stuff we no longer need	1025	# clear stuff we no longer need
764		1026
765	%$old = ();	1027	# unless (%{ $frame->[FR_STATE] }) {
766
767	unless ($repeat) {
768	delete $self->{state};	1028	# delete $self->{state};
769	delete $self->{expr};	1029	# delete $self->{expr};
770	}	1030	# }
771		1031
772	# set background pixmap	1032	# set background pixmap
773		1033
774	$self->set_background ($img, $self->{border});	1034	$self->set_background ($img, $self->{border});
775	$self->scr_recolour (0);	1035	$self->scr_recolour (0);
…		…
777	}	1037	}
778		1038
779	sub on_start {	1039	sub on_start {
780	my ($self) = @_;	1040	my ($self) = @_;
781		1041
782	my $expr = $self->x_resource ("background.expr")	1042	my $expr = $self->x_resource ("%.expr")
783	or return;	1043	or return;
784		1044
		1045	$self->has_render
		1046	or die "background extension needs RENDER extension 0.10 or higher, ignoring background-expr.\n";
		1047
785	$self->set_expr (parse_expr $expr);	1048	$self->set_expr (parse_expr $expr);
786	$self->{border} = $self->x_resource_boolean ("background.border");	1049	$self->{border} = $self->x_resource_boolean ("%.border");
		1050
		1051	$MIN_INTERVAL = $self->x_resource ("%.interval");
787		1052
788	()	1053	()
789	}	1054	}
790		1055

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Comparing rxvt-unicode/src/perl/background (file contents): Revision 1.43 by root, Sun Jun 10 11:23:20 2012 UTC vs. Revision 1.69 by root, Mon Jul 2 01:32:26 2012 UTC

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Comparing rxvt-unicode/src/perl/background (file contents):
Revision 1.43 by root, Sun Jun 10 11:23:20 2012 UTC vs.
Revision 1.69 by root, Mon Jul 2 01:32:26 2012 UTC