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

Comparing rxvt-unicode/src/perl/background (file contents):
Revision 1.42 by root, Sun Jun 10 10:42:19 2012 UTC vs.
Revision 1.71 by root, Mon Jul 2 01:40:41 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
…		…
99	its result becomes the argument to the C<scale> function.	102	its result becomes the argument to the C<scale> function.
100		103
101	Many operators also allow some parameters preceding the input image	104	Many operators also allow some parameters preceding the input image
102	that modify its behaviour. For example, C<scale> without any additional	105	that modify its behaviour. For example, C<scale> without any additional
103	arguments scales the image to size of the terminal window. If you specify	106	arguments scales the image to size of the terminal window. If you specify
104	an additional argument, it uses it as a percentage:	107	an additional argument, it uses it as a scale factor (multiply by 100 to
		108	get a percentage):
105		109
106	scale 200, load "$HOME/mypic.png"	110	scale 2, load "$HOME/mypic.png"
107		111
108	This enlarges the image by a factor of 2 (200%). As you can see, C<scale>	112	This enlarges the image by a factor of 2 (200%). As you can see, C<scale>
109	has now two arguments, the C<200> and the C<load> expression, while	113	has now two arguments, the C<200> and the C<load> expression, while
110	C<load> only has one argument. Arguments are separated from each other by	114	C<load> only has one argument. Arguments are separated from each other by
111	commas.	115	commas.
112		116
113	Scale also accepts two arguments, which are then separate factors for both	117	Scale also accepts two arguments, which are then separate factors for both
114	horizontal and vertical dimensions. For example, this halves the image	118	horizontal and vertical dimensions. For example, this halves the image
115	width and doubles the image height:	119	width and doubles the image height:
116		120
117	scale 50, 200, load "$HOME/mypic.png"	121	scale 0.5, 2, load "$HOME/mypic.png"
118		122
119	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,
120	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:
121		127
		128	scale 0.5, 2, keep { load "$HOME/mypic.png" }
		129
		130	The C<keep> operator executes all the statements inside the braces only
		131	once, or when it thinks the outcome might change. In other cases it
		132	returns the last value computed by the brace block.
		133
		134	This means that the C<load> is only executed once, which makes it much
		135	faster, but also means that more memory is being used, because the loaded
		136	image must be kept in memory at all times. In this expression, the
		137	trade-off is likely worth it.
		138
		139	But back to effects: Other effects than scaling are also readily
		140	available, for example, you can tile the image to fill the whole window,
		141	instead of resizing it:
		142
122	tile load "$HOME/mypic.png"	143	tile keep { load "$HOME/mypic.png" }
123		144
124	In fact, images returned by C<load> are in C<tile> mode by default, so the C<tile> operator	145	In fact, images returned by C<load> are in C<tile> mode by default, so the
125	is kind of superfluous.	146	C<tile> operator is kind of superfluous.
126		147
127	Another common effect is to mirror the image, so that the same edges touch:	148	Another common effect is to mirror the image, so that the same edges
		149	touch:
128		150
129	mirror load "$HOME/mypic.png"	151	mirror keep { load "$HOME/mypic.png" }
130		152
131	This is also a typical background expression:	153	Another common background expression is:
132		154
133	rootalign root	155	rootalign root
134		156
135	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
136	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
137	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:
138	moved around.	160	the image seems to be static while the window is moved around.
139		161
140	=head2 CYCLES AND CACHING	162	=head2 COLOUR SPECIFICATIONS
141		163
142	As has been mentioned before, the expression might be evaluated multiple	164	Whenever an oprator expects a "colour", then this can be specified in one
143	times. Each time the expression is reevaluated, a new cycle is said to	165	of two ways: Either as string with an X11 colour specification, such as:
144	have begun. Many operators cache their results till the next cycle.
145		166
146	For example, the C<load> operator keeps a copy of the image. If it is	167	"red" # named colour
147	asked to load the same image on the next cycle it will not load it again,	168	"#f00" # simple rgb
148	but return the cached copy.	169	"[50]red" # red with 50% alpha
		170	"TekHVC:300/50/50" # anything goes
149		171
150	This only works for one cycle though, so as long as you load the same	172	OR as an array reference with one, three or four components:
151	image every time, it will always be cached, but when you load a different
152	image, it will forget about the first one.
153		173
154	This allows you to either speed things up by keeping multiple images in	174	[0.5] # 50% gray, 100% alpha
155	memory, or comserve memory by loading images more often.	175	[0.5, 0, 0] # dark red, no green or blur, 100% alpha
		176	[0.5, 0, 0, 0.7] # same with explicit 70% alpha
156		177
157	For example, you can keep two images in memory and use a random one like	178	=head2 CACHING AND SENSITIVITY
158	this:
159		179
160	my $img1 = load "img1.png";	180	Since some operations (such as C<load> and C<blur>) can take a long time,
161	my $img2 = load "img2.png";	181	caching results can be very important for a smooth operation. Caching can
162	(0.5 > rand) ? $img1 : $img2	182	also be useful to reduce memory usage, though, for example, when an image
		183	is cached by C<load>, it could be shared by multiple terminal windows
		184	running inside urxvtd.
163		185
164	Since both images are "loaded" every time the expression is evaluated,	186	=head3 C<keep { ... }> caching
165	they are always kept in memory. Contrast this version:
166		187
167	my $path1 = "img1.png";	188	The most important way to cache expensive operations is to use C<keep {
168	my $path2 = "img2.png";	189	... }>. The C<keep> operator takes a block of multiple statements enclosed
169	load ((0.5 > rand) ? $path1 : $path2)	190	by C<{}> and keeps the return value in memory.
170		191
171	Here, a path is selected randomly, and load is only called for one image,	192	An expression can be "sensitive" to various external events, such as
172	so keeps only one image in memory. If, on the next evaluation, luck	193	scaling or moving the window, root background changes and timers. Simply
173	decides to use the other path, then it will have to load that image again.	194	using an expression (such as C<scale> without parameters) that depends on
		195	certain changing values (called "variables"), or using those variables
		196	directly, will make an expression sensitive to these events - for example,
		197	using C<scale> or C<TW> will make the expression sensitive to the terminal
		198	size, and thus to resizing events.
		199
		200	When such an event happens, C<keep> will automatically trigger a
		201	reevaluation of the whole expression with the new value of the expression.
		202
		203	C<keep> is most useful for expensive operations, such as C<blur>:
		204
		205	rootalign keep { blur 20, root }
		206
		207	This makes a blurred copy of the root background once, and on subsequent
		208	calls, just root-aligns it. Since C<blur> is usually quite slow and
		209	C<rootalign> is quite fast, this trades extra memory (for the cached
		210	blurred pixmap) with speed (blur only needs to be redone when root
		211	changes).
		212
		213	=head3 C<load> caching
		214
		215	The C<load> operator itself does not keep images in memory, but as long as
		216	the image is still in memory, C<load> will use the in-memory image instead
		217	of loading it freshly from disk.
		218
		219	That means that this expression:
		220
		221	keep { load "$HOME/path..." }
		222
		223	Not only caches the image in memory, other terminal instances that try to
		224	C<load> it can reuse that in-memory copy.
174		225
175	=head1 REFERENCE	226	=head1 REFERENCE
176		227
177	=head2 COMMAND LINE SWITCHES	228	=head2 COMMAND LINE SWITCHES
178		229
…		…
188	overwriting borders and any other areas, such as the scrollbar.	239	overwriting borders and any other areas, such as the scrollbar.
189		240
190	Specifying this flag changes the behaviour, so that the image only	241	Specifying this flag changes the behaviour, so that the image only
191	replaces the background of the character area.	242	replaces the background of the character area.
192		243
		244	=item --background-interval seconds
		245
		246	Since some operations in the underlying XRender extension can effectively
		247	freeze your X-server for prolonged time, this extension enforces a minimum
		248	time between updates, which is normally about 0.1 seconds.
		249
		250	If you want to do updates more often, you can decrease this safety
		251	interval with this switch.
		252
193	=back	253	=back
194		254
195	=cut	255	=cut
196		256
		257	our %_IMG_CACHE;
197	our $HOME;	258	our $HOME;
198	our ($self, $old, $new);	259	our ($self, $frame);
199	our ($x, $y, $w, $h);	260	our ($x, $y, $w, $h);
200		261
201	# enforce at least this interval between updates	262	# enforce at least this interval between updates
202	our $MIN_INTERVAL = 1/100;	263	our $MIN_INTERVAL = 6/59.951;
203		264
204	{	265	{
205	package urxvt::bgdsl; # background language	266	package urxvt::bgdsl; # background language
		267
		268	sub FR_PARENT() { 0 } # parent frame, if any - must be #0
		269	sub FR_CACHE () { 1 } # cached values
		270	sub FR_AGAIN () { 2 } # what this expr is sensitive to
		271	sub FR_STATE () { 3 } # watchers etc.
		272
		273	use List::Util qw(min max sum shuffle);
206		274
207	=head2 PROVIDERS/GENERATORS	275	=head2 PROVIDERS/GENERATORS
208		276
209	These functions provide an image, by loading it from disk, grabbing it	277	These functions provide an image, by loading it from disk, grabbing it
210	from the root screen or by simply generating it. They are used as starting	278	from the root screen or by simply generating it. They are used as starting
…		…
215	=item load $path	283	=item load $path
216		284
217	Loads the image at the given C<$path>. The image is set to plane tiling	285	Loads the image at the given C<$path>. The image is set to plane tiling
218	mode.	286	mode.
219		287
220	Loaded images will be cached for one cycle.	288	If the image is already in memory (e.g. because another terminal instance
		289	uses it), then the in-memory copy us returned instead.
		290
		291	=item load_uc $path
		292
		293	Load uncached - same as load, but does not cache the image, which means it
		294	is I<always> loaded from the filesystem again.
221		295
222	=cut	296	=cut
223		297
224	sub load($) {	298	sub load($) {
225	my ($path) = @_;	299	my ($path) = @_;
226		300
227	$new->{load}{$path} = $old->{load}{$path} \|\| $self->new_img_from_file ($path);	301	$_IMG_CACHE{$path} \|\| do {
		302	my $img = $self->new_img_from_file ($path);
		303	Scalar::Util::weaken ($_IMG_CACHE{$path} = $img);
		304	$img
		305	}
228	}	306	}
229		307
230	=item root	308	=item root
231		309
232	Returns the root window pixmap, that is, hopefully, the background image	310	Returns the root window pixmap, that is, hopefully, the background image
233	of your screen. The image is set to extend mode.	311	of your screen.
234		312
235	This function makes your expression root sensitive, that means it will be	313	This function makes your expression root sensitive, that means it will be
236	reevaluated when the bg image changes.	314	reevaluated when the bg image changes.
237		315
238	=cut	316	=cut
239		317
240	sub root() {	318	sub root() {
241	$new->{rootpmap_sensitive} = 1;	319	$frame->[FR_AGAIN]{rootpmap} = 1;
242	die "root op not supported, exg, we need you";	320	$self->new_img_from_root
243	}	321	}
244		322
245	=item solid $colour	323	=item solid $colour
246		324
247	=item solid $width, $height, $colour	325	=item solid $width, $height, $colour
…		…
255	=cut	333	=cut
256		334
257	sub solid($;$$) {	335	sub solid($;$$) {
258	my $colour = pop;	336	my $colour = pop;
259		337
260	my $img = $self->new_img (urxvt::PictStandardARGB32, $_[0] \|\| 1, $_[1] \|\| 1);	338	my $img = $self->new_img (urxvt::PictStandardARGB32, 0, 0, $_[0] \|\| 1, $_[1] \|\| 1);
261	$img->fill ($colour);	339	$img->fill ($colour);
262	$img	340	$img
263	}	341	}
264		342
265	=back	343	=item clone $img
266		344
267	=head2 VARIABLES	345	Returns an exact copy of the image. This is useful if you want to have
		346	multiple copies of the same image to apply different effects to.
268		347
269	The following functions provide variable data such as the terminal window
270	dimensions. They are not (Perl-) variables, they jsut return stuff that
271	varies. Most of them make your expression sensitive to some events, for
272	example using C<TW> (terminal width) means your expression is evaluated
273	again when the terminal is resized.
274
275	=over 4
276
277	=item TX
278
279	=item TY
280
281	Return the X and Y coordinates of the terminal window (the terminal
282	window is the full window by default, and the character area only when in
283	border-respect mode).
284
285	Using these functions make your expression sensitive to window moves.
286
287	These functions are mainly useful to align images to the root window.
288
289	Example: load an image and align it so it looks as if anchored to the
290	background.
291
292	move -TX, -TY, load "mybg.png"
293
294	=item TW
295
296	Return the width (C<TW>) and height (C<TH>) of the terminal window (the
297	terminal window is the full window by default, and the character area only
298	when in border-respect mode).
299
300	Using these functions make your expression sensitive to window resizes.
301
302	These functions are mainly useful to scale images, or to clip images to
303	the window size to conserve memory.
304
305	Example: take the screen background, clip it to the window size, blur it a
306	bit, align it to the window position and use it as background.
307
308	clip move -TX, -TY, blur 5, root
309
310	=cut	348	=cut
311		349
312	sub TX() { $new->{position_sensitive} = 1; $x }
313	sub TY() { $new->{position_sensitive} = 1; $y }
314	sub TW() { $new->{size_sensitive} = 1; $w }
315	sub TH() { $new->{size_sensitive} = 1; $h }
316
317	=item now
318
319	Returns the current time as (fractional) seconds since the epoch.
320
321	Using this expression does I<not> make your expression sensitive to time,
322	but the next two functions do.
323
324	=item again $seconds
325
326	When this function is used the expression will be reevaluated again in
327	C<$seconds> seconds.
328
329	Example: load some image and rotate it according to the time of day (as if it were
330	the hour pointer of a clock). Update this image every minute.
331
332	again 60; rotate TW, TH, 50, 50, (now % 86400) * -720 / 86400, scale load "myclock.png"
333
334	=item counter $seconds
335
336	Like C<again>, but also returns an increasing counter value, starting at
337	0, which might be useful for some simple animation effects.
338
339	=cut
340
341	sub now() { urxvt::NOW }
342
343	sub again($) {
344	$new->{again} = $_[0];
345	}
346
347	sub counter($) {	350	sub clone($) {
348	$new->{again} = $_[0];	351	$_[0]->clone
349	$self->{counter} + 0
350	}	352	}
351		353
352	=back	354	=item merge $img ...
		355
		356	Takes any number of images and merges them together, creating a single
		357	image containing them all. The tiling mode of the first image is used as
		358	the tiling mode of the resulting image.
		359
		360	This function is called automatically when an expression returns multiple
		361	images.
		362
		363	=cut
		364
		365	sub merge(@) {
		366	return $_[0] unless $#_;
		367
		368	# rather annoyingly clumsy, but optimisation is for another time
		369
		370	my $x0 = +1e9;
		371	my $y0 = +1e9;
		372	my $x1 = -1e9;
		373	my $y1 = -1e9;
		374
		375	for (@_) {
		376	my ($x, $y, $w, $h) = $_->geometry;
		377
		378	$x0 = $x if $x0 > $x;
		379	$y0 = $y if $y0 > $y;
		380
		381	$x += $w;
		382	$y += $h;
		383
		384	$x1 = $x if $x1 < $x;
		385	$y1 = $y if $y1 < $y;
		386	}
		387
		388	my $base = $self->new_img (urxvt::PictStandardARGB32, $x0, $y0, $x1 - $x0, $y1 - $y0);
		389	$base->repeat_mode ($_[0]->repeat_mode);
		390	$base->fill ([0, 0, 0, 0]);
		391
		392	$base->draw ($_)
		393	for @_;
		394
		395	$base
		396	}
353		397
354	=head2 TILING MODES	398	=head2 TILING MODES
355		399
356	The following operators modify the tiling mode of an image, that is, the	400	The following operators modify the tiling mode of an image, that is, the
357	way that pixels outside the image area are painted when the image is used.	401	way that pixels outside the image area are painted when the image is used.
…		…
387	become transparent. This mode is most useful when you want to place an	431	become transparent. This mode is most useful when you want to place an
388	image over another image or the background colour while leaving all	432	image over another image or the background colour while leaving all
389	background pixels outside the image unchanged.	433	background pixels outside the image unchanged.
390		434
391	Example: load an image and display it in the upper left corner. The rest	435	Example: load an image and display it in the upper left corner. The rest
392	of the space is left "empty" (transparent or wahtever your compisotr does	436	of the space is left "empty" (transparent or whatever your compositor does
393	in alpha mode, else background colour).	437	in alpha mode, else background colour).
394		438
395	pad load "mybg.png"	439	pad load "mybg.png"
396		440
397	=item extend $img	441	=item extend $img
398		442
399	Extends the image over the whole plane, using the closest pixel in the	443	Extends the image over the whole plane, using the closest pixel in the
400	area outside the image. This mode is mostly useful when you more complex	444	area outside the image. This mode is mostly useful when you use more complex
401	filtering operations and want the pixels outside the image to have the	445	filtering operations and want the pixels outside the image to have the
402	same values as the pixels near the edge.	446	same values as the pixels near the edge.
403		447
404	Example: just for curiosity, how does this pixel extension stuff work?	448	Example: just for curiosity, how does this pixel extension stuff work?
405		449
…		…
431	$img	475	$img
432	}	476	}
433		477
434	=back	478	=back
435		479
436	=head2 PIXEL OPERATORS	480	=head2 VARIABLE VALUES
437		481
438	The following operators modify the image pixels in various ways.	482	The following functions provide variable data such as the terminal window
		483	dimensions. They are not (Perl-) variables, they just return stuff that
		484	varies. Most of them make your expression sensitive to some events, for
		485	example using C<TW> (terminal width) means your expression is evaluated
		486	again when the terminal is resized.
439		487
440	=over 4	488	=over 4
441		489
442	=item clone $img	490	=item TX
443		491
444	Returns an exact copy of the image.	492	=item TY
445		493
446	=cut	494	Return the X and Y coordinates of the terminal window (the terminal
		495	window is the full window by default, and the character area only when in
		496	border-respect mode).
447		497
		498	Using these functions make your expression sensitive to window moves.
		499
		500	These functions are mainly useful to align images to the root window.
		501
		502	Example: load an image and align it so it looks as if anchored to the
		503	background (that's exactly what C<rootalign> does btw.):
		504
		505	move -TX, -TY, keep { load "mybg.png" }
		506
		507	=item TW
		508
		509	Return the width (C<TW>) and height (C<TH>) of the terminal window (the
		510	terminal window is the full window by default, and the character area only
		511	when in border-respect mode).
		512
		513	Using these functions make your expression sensitive to window resizes.
		514
		515	These functions are mainly useful to scale images, or to clip images to
		516	the window size to conserve memory.
		517
		518	Example: take the screen background, clip it to the window size, blur it a
		519	bit, align it to the window position and use it as background.
		520
		521	clip move -TX, -TY, keep { blur 5, root }
		522
		523	=cut
		524
		525	sub TX() { $frame->[FR_AGAIN]{position} = 1; $x }
		526	sub TY() { $frame->[FR_AGAIN]{position} = 1; $y }
		527	sub TW() { $frame->[FR_AGAIN]{size} = 1; $w }
		528	sub TH() { $frame->[FR_AGAIN]{size} = 1; $h }
		529
		530	=item now
		531
		532	Returns the current time as (fractional) seconds since the epoch.
		533
		534	Using this expression does I<not> make your expression sensitive to time,
		535	but the next two functions do.
		536
		537	=item again $seconds
		538
		539	When this function is used the expression will be reevaluated again in
		540	C<$seconds> seconds.
		541
		542	Example: load some image and rotate it according to the time of day (as if it were
		543	the hour pointer of a clock). Update this image every minute.
		544
		545	again 60;
		546	rotate 50, 50, (now % 86400) * -72 / 8640, scale keep { load "myclock.png" }
		547
		548	=item counter $seconds
		549
		550	Like C<again>, but also returns an increasing counter value, starting at
		551	0, which might be useful for some simple animation effects.
		552
		553	=cut
		554
		555	sub now() { urxvt::NOW }
		556
		557	sub again($) {
		558	$frame->[FR_AGAIN]{time} = $_[0];
		559	}
		560
448	sub clone($) {	561	sub counter($) {
449	$_[0]->clone	562	$frame->[FR_AGAIN]{time} = $_[0];
		563	$frame->[FR_STATE]{counter} + 0
450	}	564	}
		565
		566	=back
		567
		568	=head2 SHAPE CHANGING OPERATORS
		569
		570	The following operators modify the shape, size or position of the image.
		571
		572	=over 4
451		573
452	=item clip $img	574	=item clip $img
453		575
454	=item clip $width, $height, $img	576	=item clip $width, $height, $img
455		577
…		…
466	assumed.	588	assumed.
467		589
468	Example: load an image, blur it, and clip it to the window size to save	590	Example: load an image, blur it, and clip it to the window size to save
469	memory.	591	memory.
470		592
471	clip blur 10, load "mybg.png"	593	clip keep { blur 10, load "mybg.png" }
472		594
473	=cut	595	=cut
474		596
475	sub clip($;$$;$$) {	597	sub clip($;$$;$$) {
476	my $img = pop;	598	my $img = pop;
…		…
479	$img->sub_rect ($_[0], $_[1], $w, $h)	601	$img->sub_rect ($_[0], $_[1], $w, $h)
480	}	602	}
481		603
482	=item scale $img	604	=item scale $img
483		605
484	=item scale $size_percent, $img	606	=item scale $size_factor, $img
485		607
486	=item scale $width_percent, $height_percent, $img	608	=item scale $width_factor, $height_factor, $img
487		609
488	Scales the image by the given percentages in horizontal	610	Scales the image by the given factors in horizontal
489	(C<$width_percent>) and vertical (C<$height_percent>) direction.	611	(C<$width>) and vertical (C<$height>) direction.
490		612
491	If only one percentage is give, it is used for both directions.	613	If only one factor is give, it is used for both directions.
492		614
493	If no percentages are given, scales the image to the window size without	615	If no factors are given, scales the image to the window size without
494	keeping aspect.	616	keeping aspect.
495		617
496	=item resize $width, $height, $img	618	=item resize $width, $height, $img
497		619
498	Resizes the image to exactly C<$width> times C<$height> pixels.	620	Resizes the image to exactly C<$width> times C<$height> pixels.
499		621
500	=cut	622	=item fit $img
501		623
502	#TODO: maximise, maximise_fill?	624	=item fit $width, $height, $img
		625
		626	Fits the image into the given C<$width> and C<$height> without changing
		627	aspect, or the terminal size. That means it will be shrunk or grown until
		628	the whole image fits into the given area, possibly leaving borders.
		629
		630	=item cover $img
		631
		632	=item cover $width, $height, $img
		633
		634	Similar to C<fit>, but shrinks or grows until all of the area is covered
		635	by the image, so instead of potentially leaving borders, it will cut off
		636	image data that doesn't fit.
		637
		638	=cut
503		639
504	sub scale($;$;$) {	640	sub scale($;$;$) {
505	my $img = pop;	641	my $img = pop;
506		642
507	@_ == 2 ? $img->scale ($_[0] * $img->w * 0.01, $_[1] * $img->h * 0.01)	643	@_ == 2 ? $img->scale ($_[0] * $img->w, $_[1] * $img->h)
508	: @_ ? $img->scale ($_[0] * $img->w * 0.01, $_[0] * $img->h * 0.01)	644	: @_ ? $img->scale ($_[0] * $img->w, $_[0] * $img->h)
509	: $img->scale (TW, TH)	645	: $img->scale (TW, TH)
510	}	646	}
511		647
512	sub resize($$$) {	648	sub resize($$$) {
513	my $img = pop;	649	my $img = pop;
514	$img->scale ($_[0], $_[1])	650	$img->scale ($_[0], $_[1])
515	}	651	}
516		652
		653	sub fit($;$$) {
		654	my $img = pop;
		655	my $w = ($_[0] \|\| TW) / $img->w;
		656	my $h = ($_[1] \|\| TH) / $img->h;
		657	scale +(min $w, $h), $img
		658	}
		659
		660	sub cover($;$$) {
		661	my $img = pop;
		662	my $w = ($_[0] \|\| TW) / $img->w;
		663	my $h = ($_[1] \|\| TH) / $img->h;
		664	scale +(max $w, $h), $img
		665	}
		666
517	=item move $dx, $dy, $img	667	=item move $dx, $dy, $img
518		668
519	Moves the image by C<$dx> pixels in the horizontal, and C<$dy> pixels in	669	Moves the image by C<$dx> pixels in the horizontal, and C<$dy> pixels in
520	the vertical.	670	the vertical.
521		671
522	Example: move the image right by 20 pixels and down by 30.	672	Example: move the image right by 20 pixels and down by 30.
523		673
524	move 20, 30, ...	674	move 20, 30, ...
		675
		676	=item align $xalign, $yalign, $img
		677
		678	Aligns the image according to a factor - C<0> means the image is moved to
		679	the left or top edge (for C<$xalign> or C<$yalign>), C<0.5> means it is
		680	exactly centered and C<1> means it touches the right or bottom edge.
		681
		682	Example: remove any visible border around an image, center it vertically but move
		683	it to the right hand side.
		684
		685	align 1, 0.5, pad $img
		686
		687	=item center $img
		688
		689	=item center $width, $height, $img
		690
		691	Centers the image, i.e. the center of the image is moved to the center of
		692	the terminal window (or the box specified by C<$width> and C<$height> if
		693	given).
		694
		695	Example: load an image and center it.
		696
		697	center keep { pad load "mybg.png" }
525		698
526	=item rootalign $img	699	=item rootalign $img
527		700
528	Moves the image so that it appears glued to the screen as opposed to the	701	Moves the image so that it appears glued to the screen as opposed to the
529	window. This gives the illusion of a larger area behind the window. It is	702	window. This gives the illusion of a larger area behind the window. It is
530	exactly equivalent to C<move -TX, -TY>, that is, it moves the image to the	703	exactly equivalent to C<move -TX, -TY>, that is, it moves the image to the
531	top left of the screen.	704	top left of the screen.
532		705
533	Example: load a background image, put it in mirror mode and root align it.	706	Example: load a background image, put it in mirror mode and root align it.
534		707
535	rootalign mirror load "mybg.png"	708	rootalign keep { mirror load "mybg.png" }
536		709
537	Example: take the screen background and align it, giving the illusion of	710	Example: take the screen background and align it, giving the illusion of
538	transparency as long as the window isn't in front of other windows.	711	transparency as long as the window isn't in front of other windows.
539		712
540	rootalign root	713	rootalign root
541		714
542	=cut	715	=cut
543		716
544	sub move($$;$) {	717	sub move($$;$) {
545	my $img = pop->clone;	718	my $img = pop->clone;
546	$img->move ($_[0], $_[1]);	719	$img->move ($_[0], $_[1]);
547	$img	720	$img
548	}	721	}
549		722
		723	sub align($;$$) {
		724	my $img = pop;
		725
		726	move $_[0] * (TW - $img->w),
		727	$_[1] * (TH - $img->h),
		728	$img
		729	}
		730
		731	sub center($;$$) {
		732	my $img = pop;
		733	my $w = $_[0] \|\| TW;
		734	my $h = $_[1] \|\| TH;
		735
		736	move 0.5 * ($w - $img->w), 0.5 * ($h - $img->h), $img
		737	}
		738
550	sub rootalign($) {	739	sub rootalign($) {
551	move -TX, -TY, $_[0]	740	move -TX, -TY, $_[0]
552	}	741	}
553		742
		743	=item rotate $center_x, $center_y, $degrees, $img
		744
		745	Rotates the image clockwise by C<$degrees> degrees, around the point at
		746	C<$center_x> and C<$center_y> (specified as factor of image width/height).
		747
		748	Example: rotate the image by 90 degrees around it's center.
		749
		750	rotate 0.5, 0.5, 90, keep { load "$HOME/mybg.png" }
		751
		752	=cut
		753
		754	sub rotate($$$$) {
		755	my $img = pop;
		756	$img->rotate (
		757	$_[0] * ($img->w + $img->x),
		758	$_[1] * ($img->h + $img->y),
		759	$_[2] * (3.14159265 / 180),
		760	)
		761	}
		762
		763	=back
		764
		765	=head2 COLOUR MODIFICATIONS
		766
		767	The following operators change the pixels of the image.
		768
		769	=over 4
		770
		771	=item tint $color, $img
		772
		773	Tints the image in the given colour.
		774
		775	Example: tint the image red.
		776
		777	tint "red", load "rgb.png"
		778
		779	Example: the same, but specify the colour by component.
		780
		781	tint [1, 0, 0], load "rgb.png"
		782
		783	=cut
		784
		785	sub tint($$) {
		786	$_[1]->tint ($_[0])
		787	}
		788
554	=item contrast $factor, $img	789	=item contrast $factor, $img
555		790
556	=item contrast $r, $g, $b, $img	791	=item contrast $r, $g, $b, $img
557		792
558	=item contrast $r, $g, $b, $a, $img	793	=item contrast $r, $g, $b, $a, $img
559		794
560	Adjusts the I<contrast> of an image.	795	Adjusts the I<contrast> of an image.
561		796
562	#TODO#	797	The first form applies a single C<$factor> to red, green and blue, the
		798	second form applies separate factors to each colour channel, and the last
		799	form includes the alpha channel.
563		800
		801	Values from 0 to 1 lower the contrast, values higher than 1 increase the
		802	contrast.
		803
		804	Due to limitations in the underlying XRender extension, lowering contrast
		805	also reduces brightness, while increasing contrast currently also
		806	increases brightness.
		807
564	=item brightness $factor, $img	808	=item brightness $bias, $img
565		809
566	=item brightness $r, $g, $b, $img	810	=item brightness $r, $g, $b, $img
567		811
568	=item brightness $r, $g, $b, $a, $img	812	=item brightness $r, $g, $b, $a, $img
569		813
570	Adjusts the brightness of an image.	814	Adjusts the brightness of an image.
		815
		816	The first form applies a single C<$bias> to red, green and blue, the
		817	second form applies separate biases to each colour channel, and the last
		818	form includes the alpha channel.
		819
		820	Values less than 0 reduce brightness, while values larger than 0 increase
		821	it. Useful range is from -1 to 1 - the former results in a black, the
		822	latter in a white picture.
		823
		824	Due to idiosyncrasies in the underlying XRender extension, biases less
		825	than zero can be I<very> slow.
571		826
572	=cut	827	=cut
573		828
574	sub contrast($$;$$;$) {	829	sub contrast($$;$$;$) {
575	my $img = pop;	830	my $img = pop;
576	my ($r, $g, $b, $a) = @_;	831	my ($r, $g, $b, $a) = @_;
577		832
578	($g, $b) = ($r, $r) if @_ < 4;	833	($g, $b) = ($r, $r) if @_ < 3;
579	$a = 1 if @_ < 5;	834	$a = 1 if @_ < 4;
580		835
581	$img = $img->clone;	836	$img = $img->clone;
582	$img->contrast ($r, $g, $b, $a);	837	$img->contrast ($r, $g, $b, $a);
583	$img	838	$img
584	}	839	}
585		840
586	sub brightness($$;$$;$) {	841	sub brightness($$;$$;$) {
587	my $img = pop;	842	my $img = pop;
588	my ($r, $g, $b, $a) = @_;	843	my ($r, $g, $b, $a) = @_;
589		844
590	($g, $b) = ($r, $r) if @_ < 4;	845	($g, $b) = ($r, $r) if @_ < 3;
591	$a = 1 if @_ < 5;	846	$a = 1 if @_ < 4;
592		847
593	$img = $img->clone;	848	$img = $img->clone;
594	$img->brightness ($r, $g, $b, $a);	849	$img->brightness ($r, $g, $b, $a);
595	$img	850	$img
596	}	851	}
…		…
612	sub blur($$;$) {	867	sub blur($$;$) {
613	my $img = pop;	868	my $img = pop;
614	$img->blur ($_[0], @_ >= 2 ? $_[1] : $_[0])	869	$img->blur ($_[0], @_ >= 2 ? $_[1] : $_[0])
615	}	870	}
616		871
617	=item rotate $new_width, $new_height, $center_x, $center_y, $degrees
618
619	Rotates the image by C<$degrees> degrees, counter-clockwise, around the
620	pointer at C<$center_x> and C<$center_y> (specified as percentage of image
621	width/height), generating a new image with width C<$new_width> and height
622	C<$new_height>.
623
624	#TODO# new width, height, maybe more operators?
625
626	Example: rotate the image by 90 degrees
627
628	=cut
629
630	sub rotate($$$$$$) {
631	my $img = pop;
632	$img->rotate (
633	$_[0],
634	$_[1],
635	$_[2] * $img->w * .01,
636	$_[3] * $img->h * .01,
637	$_[4] * (3.14159265 / 180),
638	)
639	}
640
641	=back	872	=back
642		873
		874	=head2 OTHER STUFF
		875
		876	Anything that didn't fit any of the other categories, even after applying
		877	force and closing our eyes.
		878
		879	=over 4
		880
		881	=item keep { ... }
		882
		883	This operator takes a code block as argument, that is, one or more
		884	statements enclosed by braces.
		885
		886	The trick is that this code block is only evaluated when the outcome
		887	changes - on other calls the C<keep> simply returns the image it computed
		888	previously (yes, it should only be used with images). Or in other words,
		889	C<keep> I<caches> the result of the code block so it doesn't need to be
		890	computed again.
		891
		892	This can be extremely useful to avoid redoing slow operations - for
		893	example, if your background expression takes the root background, blurs it
		894	and then root-aligns it it would have to blur the root background on every
		895	window move or resize.
		896
		897	Another example is C<load>, which can be quite slow.
		898
		899	In fact, urxvt itself encloses the whole expression in some kind of
		900	C<keep> block so it only is reevaluated as required.
		901
		902	Putting the blur into a C<keep> block will make sure the blur is only done
		903	once, while the C<rootalign> is still done each time the window moves.
		904
		905	rootlign keep { blur 10, root }
		906
		907	This leaves the question of how to force reevaluation of the block,
		908	in case the root background changes: If expression inside the block
		909	is sensitive to some event (root background changes, window geometry
		910	changes), then it will be reevaluated automatically as needed.
		911
		912	=cut
		913
		914	sub keep(&) {
		915	my $id = $_[0]+0;
		916
		917	local $frame = $self->{frame_cache}{$id} \|\|= [$frame];
		918
		919	unless ($frame->[FR_CACHE]) {
		920	$frame->[FR_CACHE] = [ $_[0]() ];
		921
		922	my $self = $self;
		923	my $frame = $frame;
		924	Scalar::Util::weaken $frame;
		925	$self->compile_frame ($frame, sub {
		926	# clear this frame cache, also for all parents
		927	for (my $frame = $frame; $frame; $frame = $frame->[0]) {
		928	undef $frame->[FR_CACHE];
		929	}
		930
		931	$self->recalculate;
		932	});
		933	};
		934
		935	# in scalar context we always return the first original result, which
		936	# is not quite how perl works.
		937	wantarray
		938	? @{ $frame->[FR_CACHE] }
		939	: $frame->[FR_CACHE][0]
		940	}
		941
		942	# sub keep_clear() {
		943	# delete $self->{frame_cache};
		944	# }
		945
		946	=back
		947
643	=cut	948	=cut
644		949
645	}	950	}
646		951
647	sub parse_expr {	952	sub parse_expr {
648	my $expr = eval "sub {\npackage urxvt::bgdsl;\n#line 0 'background expression'\n$_[0]\n}";	953	my $expr = eval
		954	"sub {\n"
		955	. "package urxvt::bgdsl;\n"
		956	. "#line 0 'background expression'\n"
		957	. "$_[0]\n"
		958	. "}";
649	die if $@;	959	die if $@;
650	$expr	960	$expr
651	}	961	}
652		962
653	# compiles a parsed expression	963	# compiles a parsed expression
654	sub set_expr {	964	sub set_expr {
655	my ($self, $expr) = @_;	965	my ($self, $expr) = @_;
656		966
		967	$self->{root} = [];
657	$self->{expr} = $expr;	968	$self->{expr} = $expr;
658	$self->recalculate;	969	$self->recalculate;
		970	}
		971
		972	# takes a hash of sensitivity indicators and installs watchers
		973	sub compile_frame {
		974	my ($self, $frame, $cb) = @_;
		975
		976	my $state = $frame->[urxvt::bgdsl::FR_STATE] \|\|= {};
		977	my $again = $frame->[urxvt::bgdsl::FR_AGAIN];
		978
		979	# don't keep stuff alive
		980	Scalar::Util::weaken $state;
		981
		982	if ($again->{nested}) {
		983	$state->{nested} = 1;
		984	} else {
		985	delete $state->{nested};
		986	}
		987
		988	if (my $interval = $again->{time}) {
		989	$state->{time} = [$interval, urxvt::timer->new->after ($interval)->interval ($interval)]
		990	if $state->{time}[0] != $interval;
		991
		992	# callback might have changed, although we could just rule that out
		993	$state->{time}[1]->cb (sub {
		994	++$state->{counter};
		995	$cb->();
		996	});
		997	} else {
		998	delete $state->{time};
		999	}
		1000
		1001	if ($again->{position}) {
		1002	$state->{position} = $self->on (position_change => $cb);
		1003	} else {
		1004	delete $state->{position};
		1005	}
		1006
		1007	if ($again->{size}) {
		1008	$state->{size} = $self->on (size_change => $cb);
		1009	} else {
		1010	delete $state->{size};
		1011	}
		1012
		1013	if ($again->{rootpmap}) {
		1014	$state->{rootpmap} = $self->on (rootpmap_change => $cb);
		1015	} else {
		1016	delete $state->{rootpmap};
		1017	}
659	}	1018	}
660		1019
661	# evaluate the current bg expression	1020	# evaluate the current bg expression
662	sub recalculate {	1021	sub recalculate {
663	my ($arg_self) = @_;	1022	my ($arg_self) = @_;
…		…
673		1032
674	$arg_self->{next_refresh} = urxvt::NOW + $MIN_INTERVAL;	1033	$arg_self->{next_refresh} = urxvt::NOW + $MIN_INTERVAL;
675		1034
676	# set environment to evaluate user expression	1035	# set environment to evaluate user expression
677		1036
678	local $self = $arg_self;	1037	local $self = $arg_self;
679
680	local $HOME = $ENV{HOME};	1038	local $HOME = $ENV{HOME};
681	local $old = $self->{state};	1039	local $frame = [];
682	local $new = my $state = $self->{state} = {};
683		1040
684	($x, $y, $w, $h) =
685	$self->background_geometry ($self->{border});	1041	($x, $y, $w, $h) = $self->background_geometry ($self->{border});
686		1042
687	# evaluate user expression	1043	# evaluate user expression
688		1044
689	my $img = eval { $self->{expr}->() };	1045	my @img = eval { $self->{expr}->() };
690	warn $@ if $@;#d#	1046	die $@ if $@;
		1047	die "background-expr did not return anything.\n" unless @img;
		1048	die "background-expr: expected image(s), got something else.\n"
691	die if !UNIVERSAL::isa $img, "urxvt::img";	1049	if grep { !UNIVERSAL::isa $_, "urxvt::img" } @img;
692		1050
693	$state->{size_sensitive} = 1	1051	my $img = urxvt::bgdsl::merge @img;
		1052
		1053	$frame->[FR_AGAIN]{size} = 1
694	if $img->repeat_mode != urxvt::RepeatNormal;	1054	if $img->repeat_mode != urxvt::RepeatNormal;
695		1055
696	# if the expression is sensitive to external events, prepare reevaluation then	1056	# if the expression is sensitive to external events, prepare reevaluation then
697		1057	$self->compile_frame ($frame, sub { $arg_self->recalculate });
698	my $repeat;
699
700	if (my $again = $state->{again}) {
701	$repeat = 1;
702	my $self = $self;
703	$state->{timer} = $again == $old->{again}
704	? $old->{timer}
705	: urxvt::timer->new->after ($again)->interval ($again)->cb (sub {
706	++$self->{counter};
707	$self->recalculate
708	});
709	}
710
711	if (delete $state->{position_sensitive}) {
712	$repeat = 1;
713	$self->enable (position_change => sub { $_[0]->recalculate });
714	} else {
715	$self->disable ("position_change");
716	}
717
718	if (delete $state->{size_sensitive}) {
719	$repeat = 1;
720	$self->enable (size_change => sub { $_[0]->recalculate });
721	} else {
722	$self->disable ("size_change");
723	}
724
725	if (delete $state->{rootpmap_sensitive}) {
726	$repeat = 1;
727	$self->enable (rootpmap_change => sub { $_[0]->recalculate });
728	} else {
729	$self->disable ("rootpmap_change");
730	}
731		1058
732	# clear stuff we no longer need	1059	# clear stuff we no longer need
733		1060
734	%$old = ();	1061	# unless (%{ $frame->[FR_STATE] }) {
735
736	unless ($repeat) {
737	delete $self->{state};	1062	# delete $self->{state};
738	delete $self->{expr};	1063	# delete $self->{expr};
739	}	1064	# }
740		1065
741	# set background pixmap	1066	# set background pixmap
742		1067
743	$self->set_background ($img, $self->{border});	1068	$self->set_background ($img, $self->{border});
744	$self->scr_recolour (0);	1069	$self->scr_recolour (0);
…		…
746	}	1071	}
747		1072
748	sub on_start {	1073	sub on_start {
749	my ($self) = @_;	1074	my ($self) = @_;
750		1075
751	my $expr = $self->x_resource ("background.expr")	1076	my $expr = $self->x_resource ("%.expr")
752	or return;	1077	or return;
753		1078
		1079	$self->has_render
		1080	or die "background extension needs RENDER extension 0.10 or higher, ignoring background-expr.\n";
		1081
754	$self->set_expr (parse_expr $expr);	1082	$self->set_expr (parse_expr $expr);
755	$self->{border} = $self->x_resource_boolean ("background.border");	1083	$self->{border} = $self->x_resource_boolean ("%.border");
		1084
		1085	$MIN_INTERVAL = $self->x_resource ("%.interval");
756		1086
757	()	1087	()
758	}	1088	}
759		1089

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Comparing rxvt-unicode/src/perl/background (file contents): Revision 1.42 by root, Sun Jun 10 10:42:19 2012 UTC vs. Revision 1.71 by root, Mon Jul 2 01:40:41 2012 UTC

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Comparing rxvt-unicode/src/perl/background (file contents):
Revision 1.42 by root, Sun Jun 10 10:42:19 2012 UTC vs.
Revision 1.71 by root, Mon Jul 2 01:40:41 2012 UTC