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

Comparing rxvt-unicode/src/perl/background (file contents):
Revision 1.51 by sf-exg, Sun Jun 10 19:01:03 2012 UTC vs.
Revision 1.75 by root, Fri Aug 10 20:07:11 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 gets 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
…		…
202		276
203	=back	277	=back
204		278
205	=cut	279	=cut
206		280
207	our %_IMGCACHE;	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.	312	If the image is already in memory (e.g. because another terminal instance
		313	uses it), then the in-memory copy us returned instead.
234		314
		315	=item load_uc $path
		316
		317	Load uncached - same as load, but does not cache the image, which means it
		318	is I<always> loaded from the filesystem again, even if another copy of it
		319	is in memory at the time.
		320
235	=cut	321	=cut
		322
		323	sub load_uc($) {
		324	$self->new_img_from_file ($_[0])
		325	}
236		326
237	sub load($) {	327	sub load($) {
238	my ($path) = @_;	328	my ($path) = @_;
239		329
240	$new->{load}{$path} = $old->{load}{$path} \|\| $self->new_img_from_file ($path);	330	$_IMG_CACHE{$path} \|\| do {
		331	my $img = load_uc $path;
		332	Scalar::Util::weaken ($_IMG_CACHE{$path} = $img);
		333	$img
		334	}
241	}	335	}
242		336
243	=item root	337	=item root
244		338
245	Returns the root window pixmap, that is, hopefully, the background image	339	Returns the root window pixmap, that is, hopefully, the background image
246	of your screen. The image is set to extend mode.	340	of your screen.
247		341
248	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
249	reevaluated when the bg image changes.	343	reevaluated when the bg image changes.
250		344
251	=cut	345	=cut
252		346
253	sub root() {	347	sub root() {
254	$new->{rootpmap_sensitive} = 1;	348	$frame->[FR_AGAIN]{rootpmap} = 1;
255	die "root op not supported, exg, we need you";	349	$self->new_img_from_root
256	}	350	}
257		351
258	=item solid $colour	352	=item solid $colour
259		353
260	=item solid $width, $height, $colour	354	=item solid $width, $height, $colour
…		…
268	=cut	362	=cut
269		363
270	sub solid($;$$) {	364	sub solid($;$$) {
271	my $colour = pop;	365	my $colour = pop;
272		366
273	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);
274	$img->fill ($colour);	368	$img->fill ($colour);
275	$img	369	$img
276	}	370	}
277		371
278	=item clone $img	372	=item clone $img
…		…
284		378
285	sub clone($) {	379	sub clone($) {
286	$_[0]->clone	380	$_[0]->clone
287	}	381	}
288		382
289	=back	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	}
290		426
291	=head2 TILING MODES	427	=head2 TILING MODES
292		428
293	The following operators modify the tiling mode of an image, that is, the	429	The following operators modify the tiling mode of an image, that is, the
294	way that pixels outside the image area are painted when the image is used.	430	way that pixels outside the image area are painted when the image is used.
…		…
391	Using these functions make your expression sensitive to window moves.	527	Using these functions make your expression sensitive to window moves.
392		528
393	These functions are mainly useful to align images to the root window.	529	These functions are mainly useful to align images to the root window.
394		530
395	Example: load an image and align it so it looks as if anchored to the	531	Example: load an image and align it so it looks as if anchored to the
396	background.	532	background (that's exactly what C<rootalign> does btw.):
397		533
398	move -TX, -TY, load "mybg.png"	534	move -TX, -TY, keep { load "mybg.png" }
399		535
400	=item TW	536	=item TW
401		537
402	Return the width (C<TW>) and height (C<TH>) of the terminal window (the	538	Return the width (C<TW>) and height (C<TH>) of the terminal window (the
403	terminal window is the full window by default, and the character area only	539	terminal window is the full window by default, and the character area only
…		…
409	the window size to conserve memory.	545	the window size to conserve memory.
410		546
411	Example: take the screen background, clip it to the window size, blur it a	547	Example: take the screen background, clip it to the window size, blur it a
412	bit, align it to the window position and use it as background.	548	bit, align it to the window position and use it as background.
413		549
414	clip move -TX, -TY, blur 5, root	550	clip move -TX, -TY, keep { blur 5, root }
415		551
416	=cut	552	=cut
417		553
418	sub TX() { $new->{position_sensitive} = 1; $x }	554	sub TX() { $frame->[FR_AGAIN]{position} = 1; $x }
419	sub TY() { $new->{position_sensitive} = 1; $y }	555	sub TY() { $frame->[FR_AGAIN]{position} = 1; $y }
420	sub TW() { $new->{size_sensitive} = 1; $w }	556	sub TW() { $frame->[FR_AGAIN]{size} = 1; $w }
421	sub TH() { $new->{size_sensitive} = 1; $h }	557	sub TH() { $frame->[FR_AGAIN]{size} = 1; $h }
422		558
423	=item now	559	=item now
424		560
425	Returns the current time as (fractional) seconds since the epoch.	561	Returns the current time as (fractional) seconds since the epoch.
426		562
…		…
433	C<$seconds> seconds.	569	C<$seconds> seconds.
434		570
435	Example: load some image and rotate it according to the time of day (as if it were	571	Example: load some image and rotate it according to the time of day (as if it were
436	the hour pointer of a clock). Update this image every minute.	572	the hour pointer of a clock). Update this image every minute.
437		573
		574	again 60;
438	again 60; rotate TW, TH, 50, 50, (now % 86400) * -720 / 86400, scale load "myclock.png"	575	rotate 50, 50, (now % 86400) * -72 / 8640, scale keep { load "myclock.png" }
439		576
440	=item counter $seconds	577	=item counter $seconds
441		578
442	Like C<again>, but also returns an increasing counter value, starting at	579	Like C<again>, but also returns an increasing counter value, starting at
443	0, which might be useful for some simple animation effects.	580	0, which might be useful for some simple animation effects.
…		…
445	=cut	582	=cut
446		583
447	sub now() { urxvt::NOW }	584	sub now() { urxvt::NOW }
448		585
449	sub again($) {	586	sub again($) {
450	$new->{again} = $_[0];	587	$frame->[FR_AGAIN]{time} = $_[0];
451	}	588	}
452		589
453	sub counter($) {	590	sub counter($) {
454	$new->{again} = $_[0];	591	$frame->[FR_AGAIN]{time} = $_[0];
455	$self->{counter} + 0	592	$frame->[FR_STATE]{counter} + 0
456	}	593	}
457		594
458	=back	595	=back
459		596
460	=head2 SHAPE CHANGING OPERATORS	597	=head2 SHAPE CHANGING OPERATORS
…		…
480	assumed.	617	assumed.
481		618
482	Example: load an image, blur it, and clip it to the window size to save	619	Example: load an image, blur it, and clip it to the window size to save
483	memory.	620	memory.
484		621
485	clip blur 10, load "mybg.png"	622	clip keep { blur 10, load "mybg.png" }
486		623
487	=cut	624	=cut
488		625
489	sub clip($;$$;$$) {	626	sub clip($;$$;$$) {
490	my $img = pop;	627	my $img = pop;
…		…
584	the terminal window (or the box specified by C<$width> and C<$height> if	721	the terminal window (or the box specified by C<$width> and C<$height> if
585	given).	722	given).
586		723
587	Example: load an image and center it.	724	Example: load an image and center it.
588		725
589	center pad load "mybg.png"	726	center keep { pad load "mybg.png" }
590		727
591	=item rootalign $img	728	=item rootalign $img
592		729
593	Moves the image so that it appears glued to the screen as opposed to the	730	Moves the image so that it appears glued to the screen as opposed to the
594	window. This gives the illusion of a larger area behind the window. It is	731	window. This gives the illusion of a larger area behind the window. It is
595	exactly equivalent to C<move -TX, -TY>, that is, it moves the image to the	732	exactly equivalent to C<move -TX, -TY>, that is, it moves the image to the
596	top left of the screen.	733	top left of the screen.
597		734
598	Example: load a background image, put it in mirror mode and root align it.	735	Example: load a background image, put it in mirror mode and root align it.
599		736
600	rootalign mirror load "mybg.png"	737	rootalign keep { mirror load "mybg.png" }
601		738
602	Example: take the screen background and align it, giving the illusion of	739	Example: take the screen background and align it, giving the illusion of
603	transparency as long as the window isn't in front of other windows.	740	transparency as long as the window isn't in front of other windows.
604		741
605	rootalign root	742	rootalign root
…		…
630		767
631	sub rootalign($) {	768	sub rootalign($) {
632	move -TX, -TY, $_[0]	769	move -TX, -TY, $_[0]
633	}	770	}
634		771
		772	=item rotate $center_x, $center_y, $degrees, $img
		773
		774	Rotates the image clockwise by C<$degrees> degrees, around the point at
		775	C<$center_x> and C<$center_y> (specified as factor of image width/height).
		776
		777	Example: rotate the image by 90 degrees around it's center.
		778
		779	rotate 0.5, 0.5, 90, keep { load "$HOME/mybg.png" }
		780
		781	=cut
		782
		783	sub rotate($$$$) {
		784	my $img = pop;
		785	$img->rotate (
		786	$_[0] * ($img->w + $img->x),
		787	$_[1] * ($img->h + $img->y),
		788	$_[2] * (3.14159265 / 180),
		789	)
		790	}
		791
635	=back	792	=back
636		793
637	=head2 COLOUR MODIFICATIONS	794	=head2 COLOUR MODIFICATIONS
638		795
639	The following operators change the pixels of the image.	796	The following operators change the pixels of the image.
640		797
641	=over 4	798	=over 4
		799
		800	=item tint $color, $img
		801
		802	Tints the image in the given colour.
		803
		804	Example: tint the image red.
		805
		806	tint "red", load "rgb.png"
		807
		808	Example: the same, but specify the colour by component.
		809
		810	tint [1, 0, 0], load "rgb.png"
		811
		812	=cut
		813
		814	sub tint($$) {
		815	$_[1]->tint ($_[0])
		816	}
642		817
643	=item contrast $factor, $img	818	=item contrast $factor, $img
644		819
645	=item contrast $r, $g, $b, $img	820	=item contrast $r, $g, $b, $img
646		821
…		…
676	latter in a white picture.	851	latter in a white picture.
677		852
678	Due to idiosyncrasies in the underlying XRender extension, biases less	853	Due to idiosyncrasies in the underlying XRender extension, biases less
679	than zero can be I<very> slow.	854	than zero can be I<very> slow.
680		855
		856	You can also try the experimental(!) C<muladd> operator.
		857
681	=cut	858	=cut
682		859
683	sub contrast($$;$$;$) {	860	sub contrast($$;$$;$) {
684	my $img = pop;	861	my $img = pop;
685	my ($r, $g, $b, $a) = @_;	862	my ($r, $g, $b, $a) = @_;
…		…
700	$a = 1 if @_ < 4;	877	$a = 1 if @_ < 4;
701		878
702	$img = $img->clone;	879	$img = $img->clone;
703	$img->brightness ($r, $g, $b, $a);	880	$img->brightness ($r, $g, $b, $a);
704	$img	881	$img
		882	}
		883
		884	=item muladd $mul, $add, $img # EXPERIMENTAL
		885
		886	First multipliesthe pixels by C<$mul>, then adds C<$add>. This cna be used
		887	to implement brightness and contrast at the same time, with a wider value
		888	range than contrast and brightness operators.
		889
		890	Due to numerous bugs in XRender implementations, it can also introduce a
		891	number of visual artifacts.
		892
		893	Example: increase contrast by a factor of C<$c> without changing image
		894	brightness too much.
		895
		896	muladd $c, (1 - $c) * 0.5, $img
		897
		898	=cut
		899
		900	sub muladd($$$) {
		901	$_[2]->muladd ($_[0], $_[1])
705	}	902	}
706		903
707	=item blur $radius, $img	904	=item blur $radius, $img
708		905
709	=item blur $radius_horz, $radius_vert, $img	906	=item blur $radius_horz, $radius_vert, $img
…		…
721	sub blur($$;$) {	918	sub blur($$;$) {
722	my $img = pop;	919	my $img = pop;
723	$img->blur ($_[0], @_ >= 2 ? $_[1] : $_[0])	920	$img->blur ($_[0], @_ >= 2 ? $_[1] : $_[0])
724	}	921	}
725		922
726	=item rotate $new_width, $new_height, $center_x, $center_y, $degrees
727
728	Rotates the image by C<$degrees> degrees, counter-clockwise, around the
729	pointer at C<$center_x> and C<$center_y> (specified as factor of image
730	width/height), generating a new image with width C<$new_width> and height
731	C<$new_height>.
732
733	#TODO# new width, height, maybe more operators?
734
735	Example: rotate the image by 90 degrees
736
737	=cut
738
739	sub rotate($$$$$$) {
740	my $img = pop;
741	$img->rotate (
742	$_[0],
743	$_[1],
744	$_[2] * $img->w,
745	$_[3] * $img->h,
746	$_[4] * (3.14159265 / 180),
747	)
748	}
749
750	=back	923	=back
751		924
		925	=head2 OTHER STUFF
		926
		927	Anything that didn't fit any of the other categories, even after applying
		928	force and closing our eyes.
		929
		930	=over 4
		931
		932	=item keep { ... }
		933
		934	This operator takes a code block as argument, that is, one or more
		935	statements enclosed by braces.
		936
		937	The trick is that this code block is only evaluated when the outcome
		938	changes - on other calls the C<keep> simply returns the image it computed
		939	previously (yes, it should only be used with images). Or in other words,
		940	C<keep> I<caches> the result of the code block so it doesn't need to be
		941	computed again.
		942
		943	This can be extremely useful to avoid redoing slow operations - for
		944	example, if your background expression takes the root background, blurs it
		945	and then root-aligns it it would have to blur the root background on every
		946	window move or resize.
		947
		948	Another example is C<load>, which can be quite slow.
		949
		950	In fact, urxvt itself encloses the whole expression in some kind of
		951	C<keep> block so it only is reevaluated as required.
		952
		953	Putting the blur into a C<keep> block will make sure the blur is only done
		954	once, while the C<rootalign> is still done each time the window moves.
		955
		956	rootalign keep { blur 10, root }
		957
		958	This leaves the question of how to force reevaluation of the block,
		959	in case the root background changes: If expression inside the block
		960	is sensitive to some event (root background changes, window geometry
		961	changes), then it will be reevaluated automatically as needed.
		962
		963	=cut
		964
		965	sub keep(&) {
		966	my $id = $_[0]+0;
		967
		968	local $frame = $self->{frame_cache}{$id} \|\|= [$frame];
		969
		970	unless ($frame->[FR_CACHE]) {
		971	$frame->[FR_CACHE] = [ $_[0]() ];
		972
		973	my $self = $self;
		974	my $frame = $frame;
		975	Scalar::Util::weaken $frame;
		976	$self->compile_frame ($frame, sub {
		977	# clear this frame cache, also for all parents
		978	for (my $frame = $frame; $frame; $frame = $frame->[0]) {
		979	undef $frame->[FR_CACHE];
		980	}
		981
		982	$self->recalculate;
		983	});
		984	};
		985
		986	# in scalar context we always return the first original result, which
		987	# is not quite how perl works.
		988	wantarray
		989	? @{ $frame->[FR_CACHE] }
		990	: $frame->[FR_CACHE][0]
		991	}
		992
		993	# sub keep_clear() {
		994	# delete $self->{frame_cache};
		995	# }
		996
		997	=back
		998
752	=cut	999	=cut
753		1000
754	}	1001	}
755		1002
756	sub parse_expr {	1003	sub parse_expr {
757	my $expr = eval "sub {\npackage urxvt::bgdsl;\n#line 0 'background expression'\n$_[0]\n}";	1004	my $expr = eval
		1005	"sub {\n"
		1006	. "package urxvt::bgdsl;\n"
		1007	. "#line 0 'background expression'\n"
		1008	. "$_[0]\n"
		1009	. "}";
758	die if $@;	1010	die if $@;
759	$expr	1011	$expr
760	}	1012	}
761		1013
762	# compiles a parsed expression	1014	# compiles a parsed expression
763	sub set_expr {	1015	sub set_expr {
764	my ($self, $expr) = @_;	1016	my ($self, $expr) = @_;
765		1017
		1018	$self->{root} = []; # the outermost frame
766	$self->{expr} = $expr;	1019	$self->{expr} = $expr;
767	$self->recalculate;	1020	$self->recalculate;
		1021	}
		1022
		1023	# takes a hash of sensitivity indicators and installs watchers
		1024	sub compile_frame {
		1025	my ($self, $frame, $cb) = @_;
		1026
		1027	my $state = $frame->[urxvt::bgdsl::FR_STATE] \|\|= {};
		1028	my $again = $frame->[urxvt::bgdsl::FR_AGAIN];
		1029
		1030	# don't keep stuff alive
		1031	Scalar::Util::weaken $state;
		1032
		1033	if ($again->{nested}) {
		1034	$state->{nested} = 1;
		1035	} else {
		1036	delete $state->{nested};
		1037	}
		1038
		1039	if (my $interval = $again->{time}) {
		1040	$state->{time} = [$interval, urxvt::timer->new->after ($interval)->interval ($interval)]
		1041	if $state->{time}[0] != $interval;
		1042
		1043	# callback might have changed, although we could just rule that out
		1044	$state->{time}[1]->cb (sub {
		1045	++$state->{counter};
		1046	$cb->();
		1047	});
		1048	} else {
		1049	delete $state->{time};
		1050	}
		1051
		1052	if ($again->{position}) {
		1053	$state->{position} = $self->on (position_change => $cb);
		1054	} else {
		1055	delete $state->{position};
		1056	}
		1057
		1058	if ($again->{size}) {
		1059	$state->{size} = $self->on (size_change => $cb);
		1060	} else {
		1061	delete $state->{size};
		1062	}
		1063
		1064	if ($again->{rootpmap}) {
		1065	$state->{rootpmap} = $self->on (rootpmap_change => $cb);
		1066	} else {
		1067	delete $state->{rootpmap};
		1068	}
768	}	1069	}
769		1070
770	# evaluate the current bg expression	1071	# evaluate the current bg expression
771	sub recalculate {	1072	sub recalculate {
772	my ($arg_self) = @_;	1073	my ($arg_self) = @_;
…		…
782		1083
783	$arg_self->{next_refresh} = urxvt::NOW + $MIN_INTERVAL;	1084	$arg_self->{next_refresh} = urxvt::NOW + $MIN_INTERVAL;
784		1085
785	# set environment to evaluate user expression	1086	# set environment to evaluate user expression
786		1087
787	local $self = $arg_self;	1088	local $self = $arg_self;
788
789	local $HOME = $ENV{HOME};	1089	local $HOME = $ENV{HOME};
790	local $old = $self->{state};	1090	local $frame = $self->{root};
791	local $new = my $state = $self->{state} = {};
792		1091
793	($x, $y, $w, $h) =
794	$self->background_geometry ($self->{border});	1092	($x, $y, $w, $h) = $self->background_geometry ($self->{border});
795		1093
796	# evaluate user expression	1094	# evaluate user expression
797		1095
798	my $img = eval { $self->{expr}->() };	1096	my @img = eval { $self->{expr}->() };
799	warn $@ if $@;#d#	1097	die $@ if $@;
800	die "background-expr did not return an image.\n" if !UNIVERSAL::isa $img, "urxvt::img";	1098	die "background-expr did not return anything.\n" unless @img;
		1099	die "background-expr: expected image(s), got something else.\n"
		1100	if grep { !UNIVERSAL::isa $_, "urxvt::img" } @img;
801		1101
802	$state->{size_sensitive} = 1	1102	my $img = urxvt::bgdsl::merge @img;
		1103
		1104	$frame->[FR_AGAIN]{size} = 1
803	if $img->repeat_mode != urxvt::RepeatNormal;	1105	if $img->repeat_mode != urxvt::RepeatNormal;
804		1106
805	# if the expression is sensitive to external events, prepare reevaluation then	1107	# if the expression is sensitive to external events, prepare reevaluation then
806		1108	$self->compile_frame ($frame, sub { $arg_self->recalculate });
807	my $repeat;
808
809	if (my $again = $state->{again}) {
810	$repeat = 1;
811	my $self = $self;
812	$state->{timer} = $again == $old->{again}
813	? $old->{timer}
814	: urxvt::timer->new->after ($again)->interval ($again)->cb (sub {
815	++$self->{counter};
816	$self->recalculate
817	});
818	}
819
820	if (delete $state->{position_sensitive}) {
821	$repeat = 1;
822	$self->enable (position_change => sub { $_[0]->recalculate });
823	} else {
824	$self->disable ("position_change");
825	}
826
827	if (delete $state->{size_sensitive}) {
828	$repeat = 1;
829	$self->enable (size_change => sub { $_[0]->recalculate });
830	} else {
831	$self->disable ("size_change");
832	}
833
834	if (delete $state->{rootpmap_sensitive}) {
835	$repeat = 1;
836	$self->enable (rootpmap_change => sub { $_[0]->recalculate });
837	} else {
838	$self->disable ("rootpmap_change");
839	}
840		1109
841	# clear stuff we no longer need	1110	# clear stuff we no longer need
842		1111
843	%$old = ();	1112	# unless (%{ $frame->[FR_STATE] }) {
844
845	unless ($repeat) {
846	delete $self->{state};	1113	# delete $self->{state};
847	delete $self->{expr};	1114	# delete $self->{expr};
848	}	1115	# }
849		1116
850	# set background pixmap	1117	# set background pixmap
851		1118
852	$self->set_background ($img, $self->{border});	1119	$self->set_background ($img, $self->{border});
853	$self->scr_recolour (0);	1120	$self->scr_recolour (0);

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Comparing rxvt-unicode/src/perl/background (file contents): Revision 1.51 by sf-exg, Sun Jun 10 19:01:03 2012 UTC vs. Revision 1.75 by root, Fri Aug 10 20:07:11 2012 UTC

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Comparing rxvt-unicode/src/perl/background (file contents):
Revision 1.51 by sf-exg, Sun Jun 10 19:01:03 2012 UTC vs.
Revision 1.75 by root, Fri Aug 10 20:07:11 2012 UTC