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

Comparing rxvt-unicode/src/perl/background (file contents):
Revision 1.55 by root, Thu Jun 14 16:48:57 2012 UTC vs.
Revision 1.76 by root, Tue Aug 14 23:57:07 2012 UTC

…		…
12		12
13	urxvt --background-expr 'background expression'	13	urxvt --background-expr 'background expression'
14	--background-border	14	--background-border
15	--background-interval seconds	15	--background-interval seconds
16		16
		17	=head1 QUICK AND DIRTY CHEAT SHEET
		18
		19	Just load a random jpeg image and tile the background with it without
		20	scaling or anything else:
		21
		22	load "/path/to/img.jpg"
		23
		24	The same, but use mirroring/reflection instead of tiling:
		25
		26	mirror load "/path/to/img.jpg"
		27
		28	Load an image and scale it to exactly fill the terminal window:
		29
		30	scale keep { load "/path/to/img.jpg" }
		31
		32	Implement pseudo-transparency by using a suitably-aligned root pixmap
		33	as window background:
		34
		35	rootalign root
		36
		37	Likewise, but keep a blurred copy:
		38
		39	rootalign keep { blur 10, root }
		40
17	=head1 DESCRIPTION	41	=head1 DESCRIPTION
18		42
19	This extension manages the terminal background by creating a picture that	43	This extension manages the terminal background by creating a picture that
20	is behind the text, replacing the normal background colour.	44	is behind the text, replacing the normal background colour.
21		45
…		…
26	to be as simple as possible.	50	to be as simple as possible.
27		51
28	For example, to load an image and scale it to the window size, you would	52	For example, to load an image and scale it to the window size, you would
29	use:	53	use:
30		54
31	urxvt --background-expr 'scale load "/path/to/mybg.png"'	55	urxvt --background-expr 'scale keep { load "/path/to/mybg.png" }'
32		56
33	Or specified as a X resource:	57	Or specified as a X resource:
34		58
35	URxvt.background-expr: scale load "/path/to/mybg.png"	59	URxvt.background-expr: scale keep { load "/path/to/mybg.png" }
36		60
37	=head1 THEORY OF OPERATION	61	=head1 THEORY OF OPERATION
38		62
39	At startup, just before the window is mapped for the first time, the	63	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	64	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	77	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	78	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	79	pixmap is replaced by another one the root background changes; or when the
56	timer elapses), then the expression will be evaluated again.	80	timer elapses), then the expression will be evaluated again.
57		81
58	For example, an expression such as C<scale load "$HOME/mybg.png"> scales the	82	For example, an expression such as C<scale keep { load "$HOME/mybg.png"
59	image to the window size, so it relies on the window size and will	83	}> 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	84	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	85	example. That ensures that the picture always fills the terminal, even
62	after its size changes.	86	after its size changes.
63		87
64	=head2 EXPRESSIONS	88	=head2 EXPRESSIONS
65		89
66	Expressions are normal Perl expressions, in fact, they are Perl blocks -	90	Expressions are normal Perl expressions, in fact, they are Perl blocks -
67	which means you could use multiple lines and statements:	91	which means you could use multiple lines and statements:
68		92
		93	scale keep {
69	again 3600;	94	again 3600;
70	if (localtime now)[6]) {	95	if (localtime now)[6]) {
71	return scale load "$HOME/weekday.png";	96	return load "$HOME/weekday.png";
72	} else {	97	} else {
73	return scale load "$HOME/sunday.png";	98	return load "$HOME/sunday.png";
		99	}
74	}	100	}
75		101
76	This expression is evaluated once per hour. It will set F<sunday.png> as	102	This inner expression is evaluated once per hour (and whenever the
		103	terminal window is resized). It sets F<sunday.png> as background on
77	background on Sundays, and F<weekday.png> on all other days.	104	Sundays, and F<weekday.png> on all other days.
78		105
79	Fortunately, we expect that most expressions will be much simpler, with	106	Fortunately, we expect that most expressions will be much simpler, with
80	little Perl knowledge needed.	107	little Perl knowledge needed.
81		108
82	Basically, you always start with a function that "generates" an image	109	Basically, you always start with a function that "generates" an image
…		…
115	horizontal and vertical dimensions. For example, this halves the image	142	horizontal and vertical dimensions. For example, this halves the image
116	width and doubles the image height:	143	width and doubles the image height:
117		144
118	scale 0.5, 2, load "$HOME/mypic.png"	145	scale 0.5, 2, load "$HOME/mypic.png"
119		146
120	Other effects than scaling are also readily available, for example, you can	147	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:	148	because each time the terminal is resized, it loads the PNG image again
		149	and scales it. Scaling is usually fast (and unavoidable), but loading the
		150	image can be quite time consuming. This is where C<keep> comes in handy:
122		151
		152	scale 0.5, 2, keep { load "$HOME/mypic.png" }
		153
		154	The C<keep> operator executes all the statements inside the braces only
		155	once, or when it thinks the outcome might change. In other cases it
		156	returns the last value computed by the brace block.
		157
		158	This means that the C<load> is only executed once, which makes it much
		159	faster, but also means that more memory is being used, because the loaded
		160	image must be kept in memory at all times. In this expression, the
		161	trade-off is likely worth it.
		162
		163	But back to effects: Other effects than scaling are also readily
		164	available, for example, you can tile the image to fill the whole window,
		165	instead of resizing it:
		166
123	tile load "$HOME/mypic.png"	167	tile keep { load "$HOME/mypic.png" }
124		168
125	In fact, images returned by C<load> are in C<tile> mode by default, so the C<tile> operator	169	In fact, images returned by C<load> are in C<tile> mode by default, so the
126	is kind of superfluous.	170	C<tile> operator is kind of superfluous.
127		171
128	Another common effect is to mirror the image, so that the same edges touch:	172	Another common effect is to mirror the image, so that the same edges
		173	touch:
129		174
130	mirror load "$HOME/mypic.png"	175	mirror keep { load "$HOME/mypic.png" }
131		176
132	This is also a typical background expression:	177	Another common background expression is:
133		178
134	rootalign root	179	rootalign root
135		180
136	It first takes a snapshot of the screen background image, and then	181	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	182	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	183	left corner of the terminal window)- the result is pseudo-transparency:
139	moved around.	184	the image seems to be static while the window is moved around.
140		185
141	=head2 CYCLES AND CACHING	186	=head2 COLOUR SPECIFICATIONS
142		187
143	As has been mentioned before, the expression might be evaluated multiple	188	Whenever an operator expects a "colour", then this can be specified in one
144	times. Each time the expression is reevaluated, a new cycle is said to	189	of two ways: Either as string with an X11 colour specification, such as:
145	have begun. Many operators cache their results till the next cycle.
146		190
147	For example, the C<load> operator keeps a copy of the image. If it is	191	"red" # named colour
148	asked to load the same image on the next cycle it will not load it again,	192	"#f00" # simple rgb
149	but return the cached copy.	193	"[50]red" # red with 50% alpha
		194	"TekHVC:300/50/50" # anything goes
150		195
151	This only works for one cycle though, so as long as you load the same	196	OR as an array reference with one, three or four components:
152	image every time, it will always be cached, but when you load a different
153	image, it will forget about the first one.
154		197
155	This allows you to either speed things up by keeping multiple images in	198	[0.5] # 50% gray, 100% alpha
156	memory, or conserve memory by loading images more often.	199	[0.5, 0, 0] # dark red, no green or blur, 100% alpha
		200	[0.5, 0, 0, 0.7] # same with explicit 70% alpha
157		201
158	For example, you can keep two images in memory and use a random one like	202	=head2 CACHING AND SENSITIVITY
159	this:
160		203
161	my $img1 = load "img1.png";	204	Since some operations (such as C<load> and C<blur>) can take a long time,
162	my $img2 = load "img2.png";	205	caching results can be very important for a smooth operation. Caching can
163	(0.5 > rand) ? $img1 : $img2	206	also be useful to reduce memory usage, though, for example, when an image
		207	is cached by C<load>, it could be shared by multiple terminal windows
		208	running inside urxvtd.
164		209
165	Since both images are "loaded" every time the expression is evaluated,	210	=head3 C<keep { ... }> caching
166	they are always kept in memory. Contrast this version:
167		211
168	my $path1 = "img1.png";	212	The most important way to cache expensive operations is to use C<keep {
169	my $path2 = "img2.png";	213	... }>. The C<keep> operator takes a block of multiple statements enclosed
170	load ((0.5 > rand) ? $path1 : $path2)	214	by C<{}> and keeps the return value in memory.
171		215
172	Here, a path is selected randomly, and load is only called for one image,	216	An expression can be "sensitive" to various external events, such as
173	so keeps only one image in memory. If, on the next evaluation, luck	217	scaling or moving the window, root background changes and timers. Simply
174	decides to use the other path, then it will have to load that image again.	218	using an expression (such as C<scale> without parameters) that depends on
		219	certain changing values (called "variables"), or using those variables
		220	directly, will make an expression sensitive to these events - for example,
		221	using C<scale> or C<TW> will make the expression sensitive to the terminal
		222	size, and thus to resizing events.
		223
		224	When such an event happens, C<keep> will automatically trigger a
		225	reevaluation of the whole expression with the new value of the expression.
		226
		227	C<keep> is most useful for expensive operations, such as C<blur>:
		228
		229	rootalign keep { blur 20, root }
		230
		231	This makes a blurred copy of the root background once, and on subsequent
		232	calls, just root-aligns it. Since C<blur> is usually quite slow and
		233	C<rootalign> is quite fast, this trades extra memory (for the cached
		234	blurred pixmap) with speed (blur only needs to be redone when root
		235	changes).
		236
		237	=head3 C<load> caching
		238
		239	The C<load> operator itself does not keep images in memory, but as long as
		240	the image is still in memory, C<load> will use the in-memory image instead
		241	of loading it freshly from disk.
		242
		243	That means that this expression:
		244
		245	keep { load "$HOME/path..." }
		246
		247	Not only caches the image in memory, other terminal instances that try to
		248	C<load> it can reuse that in-memory copy.
175		249
176	=head1 REFERENCE	250	=head1 REFERENCE
177		251
178	=head2 COMMAND LINE SWITCHES	252	=head2 COMMAND LINE SWITCHES
179		253
…		…
204		278
205	=cut	279	=cut
206		280
207	our %_IMG_CACHE;	281	our %_IMG_CACHE;
208	our $HOME;	282	our $HOME;
209	our ($self, $old, $new);	283	our ($self, $frame);
210	our ($x, $y, $w, $h);	284	our ($x, $y, $w, $h);
211		285
212	# enforce at least this interval between updates	286	# enforce at least this interval between updates
213	our $MIN_INTERVAL = 6/59.951;	287	our $MIN_INTERVAL = 6/59.951;
214		288
215	{	289	{
216	package urxvt::bgdsl; # background language	290	package urxvt::bgdsl; # background language
		291
		292	sub FR_PARENT() { 0 } # parent frame, if any - must be #0
		293	sub FR_CACHE () { 1 } # cached values
		294	sub FR_AGAIN () { 2 } # what this expr is sensitive to
		295	sub FR_STATE () { 3 } # watchers etc.
217		296
218	use List::Util qw(min max sum shuffle);	297	use List::Util qw(min max sum shuffle);
219		298
220	=head2 PROVIDERS/GENERATORS	299	=head2 PROVIDERS/GENERATORS
221		300
…		…
228	=item load $path	307	=item load $path
229		308
230	Loads the image at the given C<$path>. The image is set to plane tiling	309	Loads the image at the given C<$path>. The image is set to plane tiling
231	mode.	310	mode.
232		311
233	Loaded images will be cached for one cycle, and shared between temrinals	312	If the image is already in memory (e.g. because another terminal instance
234	running in the same process (e.g. in C<urxvtd>).	313	uses it), then the in-memory copy us returned instead.
235		314
236	=item load_uc $path	315	=item load_uc $path
237		316
238	Load uncached - same as load, but does not cache the image. This function	317	Load uncached - same as load, but does not cache the image, which means it
239	is most useufl if you want to optimise a background expression in some	318	is I<always> loaded from the filesystem again, even if another copy of it
240	way.	319	is in memory at the time.
241		320
242	=cut	321	=cut
243		322
244	sub load_uc($) {	323	sub load_uc($) {
		324	$self->new_img_from_file ($_[0])
		325	}
		326
		327	sub load($) {
245	my ($path) = @_;	328	my ($path) = @_;
246		329
247	$_IMG_CACHE{$path} \|\| do {	330	$_IMG_CACHE{$path} \|\| do {
248	my $img = $self->new_img_from_file ($path);	331	my $img = load_uc $path;
249	Scalar::Util::weaken ($_IMG_CACHE{$path} = $img);	332	Scalar::Util::weaken ($_IMG_CACHE{$path} = $img);
250	$img	333	$img
251	}	334	}
252	}	335	}
253		336
254	sub load($) {
255	my ($path) = @_;
256
257	$new->{load}{$path} = $old->{load}{$path} \|\| load_uc $path;
258	}
259
260	=item root	337	=item root
261		338
262	Returns the root window pixmap, that is, hopefully, the background image	339	Returns the root window pixmap, that is, hopefully, the background image
263	of your screen. The image is set to extend mode.	340	of your screen.
264		341
265	This function makes your expression root sensitive, that means it will be	342	This function makes your expression root sensitive, that means it will be
266	reevaluated when the bg image changes.	343	reevaluated when the bg image changes.
267		344
268	=cut	345	=cut
269		346
270	sub root() {	347	sub root() {
271	$new->{again}{rootpmap} = 1;	348	$frame->[FR_AGAIN]{rootpmap} = 1;
272	$self->new_img_from_root	349	$self->new_img_from_root
273	}	350	}
274		351
275	=item solid $colour	352	=item solid $colour
276		353
…		…
285	=cut	362	=cut
286		363
287	sub solid($;$$) {	364	sub solid($;$$) {
288	my $colour = pop;	365	my $colour = pop;
289		366
290	my $img = $self->new_img (urxvt::PictStandardARGB32, $_[0] \|\| 1, $_[1] \|\| 1);	367	my $img = $self->new_img (urxvt::PictStandardARGB32, 0, 0, $_[0] \|\| 1, $_[1] \|\| 1);
291	$img->fill ($colour);	368	$img->fill ($colour);
292	$img	369	$img
293	}	370	}
294		371
295	=item clone $img	372	=item clone $img
…		…
300	=cut	377	=cut
301		378
302	sub clone($) {	379	sub clone($) {
303	$_[0]->clone	380	$_[0]->clone
304	}	381	}
		382
		383	=item merge $img ...
		384
		385	Takes any number of images and merges them together, creating a single
		386	image containing them all. The tiling mode of the first image is used as
		387	the tiling mode of the resulting image.
		388
		389	This function is called automatically when an expression returns multiple
		390	images.
		391
		392	=cut
		393
		394	sub merge(@) {
		395	return $_[0] unless $#_;
		396
		397	# rather annoyingly clumsy, but optimisation is for another time
		398
		399	my $x0 = +1e9;
		400	my $y0 = +1e9;
		401	my $x1 = -1e9;
		402	my $y1 = -1e9;
		403
		404	for (@_) {
		405	my ($x, $y, $w, $h) = $_->geometry;
		406
		407	$x0 = $x if $x0 > $x;
		408	$y0 = $y if $y0 > $y;
		409
		410	$x += $w;
		411	$y += $h;
		412
		413	$x1 = $x if $x1 < $x;
		414	$y1 = $y if $y1 < $y;
		415	}
		416
		417	my $base = $self->new_img (urxvt::PictStandardARGB32, $x0, $y0, $x1 - $x0, $y1 - $y0);
		418	$base->repeat_mode ($_[0]->repeat_mode);
		419	$base->fill ([0, 0, 0, 0]);
		420
		421	$base->draw ($_)
		422	for @_;
		423
		424	$base
		425	}
		426
		427	=back
305		428
306	=head2 TILING MODES	429	=head2 TILING MODES
307		430
308	The following operators modify the tiling mode of an image, that is, the	431	The following operators modify the tiling mode of an image, that is, the
309	way that pixels outside the image area are painted when the image is used.	432	way that pixels outside the image area are painted when the image is used.
…		…
406	Using these functions make your expression sensitive to window moves.	529	Using these functions make your expression sensitive to window moves.
407		530
408	These functions are mainly useful to align images to the root window.	531	These functions are mainly useful to align images to the root window.
409		532
410	Example: load an image and align it so it looks as if anchored to the	533	Example: load an image and align it so it looks as if anchored to the
411	background.	534	background (that's exactly what C<rootalign> does btw.):
412		535
413	move -TX, -TY, load "mybg.png"	536	move -TX, -TY, keep { load "mybg.png" }
414		537
415	=item TW	538	=item TW
416		539
417	Return the width (C<TW>) and height (C<TH>) of the terminal window (the	540	Return the width (C<TW>) and height (C<TH>) of the terminal window (the
418	terminal window is the full window by default, and the character area only	541	terminal window is the full window by default, and the character area only
…		…
424	the window size to conserve memory.	547	the window size to conserve memory.
425		548
426	Example: take the screen background, clip it to the window size, blur it a	549	Example: take the screen background, clip it to the window size, blur it a
427	bit, align it to the window position and use it as background.	550	bit, align it to the window position and use it as background.
428		551
429	clip move -TX, -TY, once { blur 5, root }	552	clip move -TX, -TY, keep { blur 5, root }
430		553
431	=cut	554	=cut
432		555
433	sub TX() { $new->{again}{position} = 1; $x }	556	sub TX() { $frame->[FR_AGAIN]{position} = 1; $x }
434	sub TY() { $new->{again}{position} = 1; $y }	557	sub TY() { $frame->[FR_AGAIN]{position} = 1; $y }
435	sub TW() { $new->{again}{size} = 1; $w }	558	sub TW() { $frame->[FR_AGAIN]{size} = 1; $w }
436	sub TH() { $new->{again}{size} = 1; $h }	559	sub TH() { $frame->[FR_AGAIN]{size} = 1; $h }
437		560
438	=item now	561	=item now
439		562
440	Returns the current time as (fractional) seconds since the epoch.	563	Returns the current time as (fractional) seconds since the epoch.
441		564
…		…
448	C<$seconds> seconds.	571	C<$seconds> seconds.
449		572
450	Example: load some image and rotate it according to the time of day (as if it were	573	Example: load some image and rotate it according to the time of day (as if it were
451	the hour pointer of a clock). Update this image every minute.	574	the hour pointer of a clock). Update this image every minute.
452		575
		576	again 60;
453	again 60; rotate 50, 50, (now % 86400) * -720 / 86400, scale load "myclock.png"	577	rotate 50, 50, (now % 86400) * -72 / 8640, scale keep { load "myclock.png" }
454		578
455	=item counter $seconds	579	=item counter $seconds
456		580
457	Like C<again>, but also returns an increasing counter value, starting at	581	Like C<again>, but also returns an increasing counter value, starting at
458	0, which might be useful for some simple animation effects.	582	0, which might be useful for some simple animation effects.
…		…
460	=cut	584	=cut
461		585
462	sub now() { urxvt::NOW }	586	sub now() { urxvt::NOW }
463		587
464	sub again($) {	588	sub again($) {
465	$new->{again}{time} = $_[0];	589	$frame->[FR_AGAIN]{time} = $_[0];
466	}	590	}
467		591
468	sub counter($) {	592	sub counter($) {
469	$new->{again}{time} = $_[0];	593	$frame->[FR_AGAIN]{time} = $_[0];
470	$self->{counter} + 0	594	$frame->[FR_STATE]{counter} + 0
471	}	595	}
472		596
473	=back	597	=back
474		598
475	=head2 SHAPE CHANGING OPERATORS	599	=head2 SHAPE CHANGING OPERATORS
…		…
495	assumed.	619	assumed.
496		620
497	Example: load an image, blur it, and clip it to the window size to save	621	Example: load an image, blur it, and clip it to the window size to save
498	memory.	622	memory.
499		623
500	clip blur 10, load "mybg.png"	624	clip keep { blur 10, load "mybg.png" }
501		625
502	=cut	626	=cut
503		627
504	sub clip($;$$;$$) {	628	sub clip($;$$;$$) {
505	my $img = pop;	629	my $img = pop;
…		…
599	the terminal window (or the box specified by C<$width> and C<$height> if	723	the terminal window (or the box specified by C<$width> and C<$height> if
600	given).	724	given).
601		725
602	Example: load an image and center it.	726	Example: load an image and center it.
603		727
604	center pad load "mybg.png"	728	center keep { pad load "mybg.png" }
605		729
606	=item rootalign $img	730	=item rootalign $img
607		731
608	Moves the image so that it appears glued to the screen as opposed to the	732	Moves the image so that it appears glued to the screen as opposed to the
609	window. This gives the illusion of a larger area behind the window. It is	733	window. This gives the illusion of a larger area behind the window. It is
610	exactly equivalent to C<move -TX, -TY>, that is, it moves the image to the	734	exactly equivalent to C<move -TX, -TY>, that is, it moves the image to the
611	top left of the screen.	735	top left of the screen.
612		736
613	Example: load a background image, put it in mirror mode and root align it.	737	Example: load a background image, put it in mirror mode and root align it.
614		738
615	rootalign mirror load "mybg.png"	739	rootalign keep { mirror load "mybg.png" }
616		740
617	Example: take the screen background and align it, giving the illusion of	741	Example: take the screen background and align it, giving the illusion of
618	transparency as long as the window isn't in front of other windows.	742	transparency as long as the window isn't in front of other windows.
619		743
620	rootalign root	744	rootalign root
…		…
645		769
646	sub rootalign($) {	770	sub rootalign($) {
647	move -TX, -TY, $_[0]	771	move -TX, -TY, $_[0]
648	}	772	}
649		773
650	=item rotate $center_x, $center_y, $degrees	774	=item rotate $center_x, $center_y, $degrees, $img
651		775
652	Rotates the image by C<$degrees> degrees, counter-clockwise, around the	776	Rotates the image clockwise by C<$degrees> degrees, around the point at
653	pointer at C<$center_x> and C<$center_y> (specified as factor of image	777	C<$center_x> and C<$center_y> (specified as factor of image width/height).
654	width/height).
655		778
656	#TODO# new width, height, maybe more operators?
657
658	Example: rotate the image by 90 degrees	779	Example: rotate the image by 90 degrees around it's center.
		780
		781	rotate 0.5, 0.5, 90, keep { load "$HOME/mybg.png" }
659		782
660	=cut	783	=cut
661		784
662	sub rotate($$$$) {	785	sub rotate($$$$) {
663	my $img = pop;	786	my $img = pop;
664	$img->rotate (	787	$img->rotate (
665	$_[0] * $img->w,	788	$_[0] * ($img->w + $img->x),
666	$_[1] * $img->h,	789	$_[1] * ($img->h + $img->y),
667	$_[2] * (3.14159265 / 180),	790	$_[2] * (3.14159265 / 180),
668	)	791	)
669	}	792	}
670		793
671	=back	794	=back
…		…
673	=head2 COLOUR MODIFICATIONS	796	=head2 COLOUR MODIFICATIONS
674		797
675	The following operators change the pixels of the image.	798	The following operators change the pixels of the image.
676		799
677	=over 4	800	=over 4
		801
		802	=item tint $color, $img
		803
		804	Tints the image in the given colour.
		805
		806	Example: tint the image red.
		807
		808	tint "red", load "rgb.png"
		809
		810	Example: the same, but specify the colour by component.
		811
		812	tint [1, 0, 0], load "rgb.png"
		813
		814	=cut
		815
		816	sub tint($$) {
		817	$_[1]->tint ($_[0])
		818	}
678		819
679	=item contrast $factor, $img	820	=item contrast $factor, $img
680		821
681	=item contrast $r, $g, $b, $img	822	=item contrast $r, $g, $b, $img
682		823
…		…
712	latter in a white picture.	853	latter in a white picture.
713		854
714	Due to idiosyncrasies in the underlying XRender extension, biases less	855	Due to idiosyncrasies in the underlying XRender extension, biases less
715	than zero can be I<very> slow.	856	than zero can be I<very> slow.
716		857
		858	You can also try the experimental(!) C<muladd> operator.
		859
717	=cut	860	=cut
718		861
719	sub contrast($$;$$;$) {	862	sub contrast($$;$$;$) {
720	my $img = pop;	863	my $img = pop;
721	my ($r, $g, $b, $a) = @_;	864	my ($r, $g, $b, $a) = @_;
…		…
736	$a = 1 if @_ < 4;	879	$a = 1 if @_ < 4;
737		880
738	$img = $img->clone;	881	$img = $img->clone;
739	$img->brightness ($r, $g, $b, $a);	882	$img->brightness ($r, $g, $b, $a);
740	$img	883	$img
		884	}
		885
		886	=item muladd $mul, $add, $img # EXPERIMENTAL
		887
		888	First multipliesthe pixels by C<$mul>, then adds C<$add>. This cna be used
		889	to implement brightness and contrast at the same time, with a wider value
		890	range than contrast and brightness operators.
		891
		892	Due to numerous bugs in XRender implementations, it can also introduce a
		893	number of visual artifacts.
		894
		895	Example: increase contrast by a factor of C<$c> without changing image
		896	brightness too much.
		897
		898	muladd $c, (1 - $c) * 0.5, $img
		899
		900	=cut
		901
		902	sub muladd($$$) {
		903	$_[2]->muladd ($_[0], $_[1])
741	}	904	}
742		905
743	=item blur $radius, $img	906	=item blur $radius, $img
744		907
745	=item blur $radius_horz, $radius_vert, $img	908	=item blur $radius_horz, $radius_vert, $img
…		…
761		924
762	=back	925	=back
763		926
764	=head2 OTHER STUFF	927	=head2 OTHER STUFF
765		928
766	Anything that didn't fit any of the other categories, even after appliyng	929	Anything that didn't fit any of the other categories, even after applying
767	force and closing our eyes.	930	force and closing our eyes.
768		931
769	=over 4	932	=over 4
770		933
771	=item once { ... }	934	=item keep { ... }
772		935
773	This function takes a code block as argument, that is, one or more	936	This operator takes a code block as argument, that is, one or more
774	statements enclosed by braces.	937	statements enclosed by braces.
775		938
776	The trick is that this code block is only evaluated once - future calls	939	The trick is that this code block is only evaluated when the outcome
777	will simply return the original image (yes, it should only be used with	940	changes - on other calls the C<keep> simply returns the image it computed
778	images).	941	previously (yes, it should only be used with images). Or in other words,
		942	C<keep> I<caches> the result of the code block so it doesn't need to be
		943	computed again.
779		944
780	This can be extremely useful to avoid redoign the same slow operations	945	This can be extremely useful to avoid redoing slow operations - for
781	again and again- for example, if your background expression takes the root	946	example, if your background expression takes the root background, blurs it
782	background, blurs it and then root-aligns it it would have to blur the	947	and then root-aligns it it would have to blur the root background on every
783	root background on every window move or resize.	948	window move or resize.
784		949
		950	Another example is C<load>, which can be quite slow.
		951
		952	In fact, urxvt itself encloses the whole expression in some kind of
		953	C<keep> block so it only is reevaluated as required.
		954
785	Putting the blur into a C<once> block will make sure the blur is only done	955	Putting the blur into a C<keep> block will make sure the blur is only done
786	once:	956	once, while the C<rootalign> is still done each time the window moves.
787		957
788	rootlign once { blur 10, root }	958	rootalign keep { blur 10, root }
789		959
790	This leaves the question of how to force reevaluation of the block, in	960	This leaves the question of how to force reevaluation of the block,
791	case the root background changes: Right now, all once blocks forget that	961	in case the root background changes: If expression inside the block
792	they ahve been executed before each time the root background changes (if	962	is sensitive to some event (root background changes, window geometry
793	the expression is sensitive to that) or when C<once_again> is called.	963	changes), then it will be reevaluated automatically as needed.
794		964
795	=item once_again
796
797	Resets all C<once> block as if they had never been called, i.e. on the
798	next call they will be reevaluated again.
799
800	=cut	965	=cut
801		966
802	sub once(&) {	967	sub keep(&) {
803	my $once = $self->{once_cache}{$_[0]+0} \|\|= do {	968	my $id = $_[0]+0;
804	local $new->{again};	969
805	my @res = $_[0]();	970	local $frame = $self->{frame_cache}{$id} \|\|= [$frame];
806	[$new->{again}, \@res]	971
		972	unless ($frame->[FR_CACHE]) {
		973	$frame->[FR_CACHE] = [ $_[0]() ];
		974
		975	my $self = $self;
		976	my $frame = $frame;
		977	Scalar::Util::weaken $frame;
		978	$self->compile_frame ($frame, sub {
		979	# clear this frame cache, also for all parents
		980	for (my $frame = $frame; $frame; $frame = $frame->[0]) {
		981	undef $frame->[FR_CACHE];
		982	}
		983
		984	$self->recalculate;
807	};	985	});
808
809	$new->{again} = {
810	%{ $new->{again} },
811	%{ $once->[0] }
812	};	986	};
813		987
814	# in scalar context we always return the first original result, which	988	# in scalar context we always return the first original result, which
815	# is not quite how perl works.	989	# is not quite how perl works.
816	wantarray	990	wantarray
817	? @{ $once->[1] }	991	? @{ $frame->[FR_CACHE] }
818	: $once->[1][0]	992	: $frame->[FR_CACHE][0]
		993	}
		994
		995	# sub keep_clear() {
		996	# delete $self->{frame_cache};
819	}	997	# }
820
821	sub once_again() {
822	delete $self->{once_cache};
823	}
824		998
825	=back	999	=back
826		1000
827	=cut	1001	=cut
828		1002
829	}	1003	}
830		1004
831	sub parse_expr {	1005	sub parse_expr {
832	my $expr = eval "sub {\npackage urxvt::bgdsl;\n#line 0 'background expression'\n$_[0]\n}";	1006	my $expr = eval
		1007	"sub {\n"
		1008	. "package urxvt::bgdsl;\n"
		1009	. "#line 0 'background expression'\n"
		1010	. "$_[0]\n"
		1011	. "}";
833	die if $@;	1012	die if $@;
834	$expr	1013	$expr
835	}	1014	}
836		1015
837	# compiles a parsed expression	1016	# compiles a parsed expression
838	sub set_expr {	1017	sub set_expr {
839	my ($self, $expr) = @_;	1018	my ($self, $expr) = @_;
840		1019
		1020	$self->{root} = []; # the outermost frame
841	$self->{expr} = $expr;	1021	$self->{expr} = $expr;
842	$self->recalculate;	1022	$self->recalculate;
		1023	}
		1024
		1025	# takes a hash of sensitivity indicators and installs watchers
		1026	sub compile_frame {
		1027	my ($self, $frame, $cb) = @_;
		1028
		1029	my $state = $frame->[urxvt::bgdsl::FR_STATE] \|\|= {};
		1030	my $again = $frame->[urxvt::bgdsl::FR_AGAIN];
		1031
		1032	# don't keep stuff alive
		1033	Scalar::Util::weaken $state;
		1034
		1035	if ($again->{nested}) {
		1036	$state->{nested} = 1;
		1037	} else {
		1038	delete $state->{nested};
		1039	}
		1040
		1041	if (my $interval = $again->{time}) {
		1042	$state->{time} = [$interval, urxvt::timer->new->after ($interval)->interval ($interval)]
		1043	if $state->{time}[0] != $interval;
		1044
		1045	# callback might have changed, although we could just rule that out
		1046	$state->{time}[1]->cb (sub {
		1047	++$state->{counter};
		1048	$cb->();
		1049	});
		1050	} else {
		1051	delete $state->{time};
		1052	}
		1053
		1054	if ($again->{position}) {
		1055	$state->{position} = $self->on (position_change => $cb);
		1056	} else {
		1057	delete $state->{position};
		1058	}
		1059
		1060	if ($again->{size}) {
		1061	$state->{size} = $self->on (size_change => $cb);
		1062	} else {
		1063	delete $state->{size};
		1064	}
		1065
		1066	if ($again->{rootpmap}) {
		1067	$state->{rootpmap} = $self->on (rootpmap_change => $cb);
		1068	} else {
		1069	delete $state->{rootpmap};
		1070	}
843	}	1071	}
844		1072
845	# evaluate the current bg expression	1073	# evaluate the current bg expression
846	sub recalculate {	1074	sub recalculate {
847	my ($arg_self) = @_;	1075	my ($arg_self) = @_;
…		…
857		1085
858	$arg_self->{next_refresh} = urxvt::NOW + $MIN_INTERVAL;	1086	$arg_self->{next_refresh} = urxvt::NOW + $MIN_INTERVAL;
859		1087
860	# set environment to evaluate user expression	1088	# set environment to evaluate user expression
861		1089
862	local $self = $arg_self;	1090	local $self = $arg_self;
863
864	local $HOME = $ENV{HOME};	1091	local $HOME = $ENV{HOME};
865	local $old = $self->{state};	1092	local $frame = $self->{root};
866	local $new = my $state = $self->{state} = {};
867		1093
868	($x, $y, $w, $h) =
869	$self->background_geometry ($self->{border});	1094	($x, $y, $w, $h) = $self->background_geometry ($self->{border});
870		1095
871	# evaluate user expression	1096	# evaluate user expression
872		1097
873	my $img = eval { $self->{expr}->() };	1098	my @img = eval { $self->{expr}->() };
874	warn $@ if $@;#d#	1099	die $@ if $@;
875	die "background-expr did not return an image.\n" if !UNIVERSAL::isa $img, "urxvt::img";	1100	die "background-expr did not return anything.\n" unless @img;
		1101	die "background-expr: expected image(s), got something else.\n"
		1102	if grep { !UNIVERSAL::isa $_, "urxvt::img" } @img;
		1103
		1104	my $img = urxvt::bgdsl::merge @img;
		1105
		1106	$frame->[FR_AGAIN]{size} = 1
		1107	if $img->repeat_mode != urxvt::RepeatNormal;
876		1108
877	# if the expression is sensitive to external events, prepare reevaluation then	1109	# if the expression is sensitive to external events, prepare reevaluation then
878		1110	$self->compile_frame ($frame, sub { $arg_self->recalculate });
879	my $again = delete $state->{again};
880
881	$again->{size} = 1
882	if $img->repeat_mode != urxvt::RepeatNormal;
883
884	if (my $again = $again->{time}) {
885	my $self = $self;
886	$state->{timer} = $again == $old->{again}
887	? $old->{timer}
888	: urxvt::timer->new->after ($again)->interval ($again)->cb (sub {
889	++$self->{counter};
890	$self->recalculate
891	});
892	}
893
894	if ($again->{position}) {
895	$self->enable (position_change => sub { $_[0]->recalculate });
896	} else {
897	$self->disable ("position_change");
898	}
899
900	if ($again->{size}) {
901	$self->enable (size_change => sub { $_[0]->recalculate });
902	} else {
903	$self->disable ("size_change");
904	}
905
906	if ($again->{rootpmap}) {
907	$self->enable (rootpmap_change => sub {
908	delete $_[0]{once_cache}; # this will override once-block values from
909	$_[0]->recalculate;
910	});
911	} else {
912	$self->disable ("rootpmap_change");
913	}
914		1111
915	# clear stuff we no longer need	1112	# clear stuff we no longer need
916		1113
917	%$old = ();	1114	# unless (%{ $frame->[FR_STATE] }) {
918
919	unless (%$again) {
920	delete $self->{state};	1115	# delete $self->{state};
921	delete $self->{expr};	1116	# delete $self->{expr};
922	}	1117	# }
923		1118
924	# set background pixmap	1119	# set background pixmap
925		1120
926	$self->set_background ($img, $self->{border});	1121	$self->set_background ($img, $self->{border});
927	$self->scr_recolour (0);	1122	$self->scr_recolour (0);

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Comparing rxvt-unicode/src/perl/background (file contents): Revision 1.55 by root, Thu Jun 14 16:48:57 2012 UTC vs. Revision 1.76 by root, Tue Aug 14 23:57:07 2012 UTC

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Comparing rxvt-unicode/src/perl/background (file contents):
Revision 1.55 by root, Thu Jun 14 16:48:57 2012 UTC vs.
Revision 1.76 by root, Tue Aug 14 23:57:07 2012 UTC