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

Comparing rxvt-unicode/src/perl/background (file contents):
Revision 1.3 by root, Tue Jun 5 12:08:23 2012 UTC vs.
Revision 1.55 by root, Thu Jun 14 16:48:57 2012 UTC

…		…
1	#! perl	1	#! perl
2		2
3	our $EXPR = 'move load "/root/pix/das_fette_schwein.jpg", left, top';	3	#:META:X_RESOURCE:%.expr:string:background expression
4	#$EXPR = 'blur root, 10, 10'	4	#:META:X_RESOURCE:%.border:boolean:respect the terminal border
5	#$EXPR = 'blur move (root, -x, -y), 5, 5'	5	#:META:X_RESOURCE:%.interval:seconds:minimum time between updates
6	#resize load "/root/pix/das_fette_schwein.jpg", w, h
7		6
8	use Safe;	7	=head1 NAME
9		8
		9	background - manage terminal background
		10
		11	=head1 SYNOPSIS
		12
		13	urxvt --background-expr 'background expression'
		14	--background-border
		15	--background-interval seconds
		16
		17	=head1 DESCRIPTION
		18
		19	This extension manages the terminal background by creating a picture that
		20	is behind the text, replacing the normal background colour.
		21
		22	It does so by evaluating a Perl expression that I<calculates> the image on
		23	the fly, for example, by grabbing the root background or loading a file.
		24
		25	While the full power of Perl is available, the operators have been design
		26	to be as simple as possible.
		27
		28	For example, to load an image and scale it to the window size, you would
		29	use:
		30
		31	urxvt --background-expr 'scale load "/path/to/mybg.png"'
		32
		33	Or specified as a X resource:
		34
		35	URxvt.background-expr: scale load "/path/to/mybg.png"
		36
		37	=head1 THEORY OF OPERATION
		38
		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
		41	extended as necessary to cover the whole terminal window, and is set as a
		42	background pixmap.
		43
		44	If the image contains an alpha channel, then it will be used as-is in
		45	visuals that support alpha channels (for example, for a compositing
		46	manager). In other visuals, the terminal background colour will be used to
		47	replace any transparency.
		48
		49	When the expression relies, directly or indirectly, on the window size,
		50	position, the root pixmap, or a timer, then it will be remembered. If not,
		51	then it will be removed.
		52
		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
		55	pixmap is replaced by another one the root background changes; or when the
		56	timer elapses), then the expression will be evaluated again.
		57
		58	For example, an expression such as C<scale load "$HOME/mybg.png"> scales the
		59	image to the window size, so it relies on the window size and will
		60	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
		62	after its size changes.
		63
		64	=head2 EXPRESSIONS
		65
		66	Expressions are normal Perl expressions, in fact, they are Perl blocks -
		67	which means you could use multiple lines and statements:
		68
		69	again 3600;
		70	if (localtime now)[6]) {
		71	return scale load "$HOME/weekday.png";
		72	} else {
		73	return scale load "$HOME/sunday.png";
		74	}
		75
		76	This expression is evaluated once per hour. It will set F<sunday.png> as
		77	background on Sundays, and F<weekday.png> on all other days.
		78
		79	Fortunately, we expect that most expressions will be much simpler, with
		80	little Perl knowledge needed.
		81
		82	Basically, you always start with a function that "generates" an image
		83	object, such as C<load>, which loads an image from disk, or C<root>, which
		84	returns the root window background image:
		85
		86	load "$HOME/mypic.png"
		87
		88	The path is usually specified as a quoted string (the exact rules can be
		89	found in the L<perlop> manpage). The F<$HOME> at the beginning of the
		90	string is expanded to the home directory.
		91
		92	Then you prepend one or more modifiers or filtering expressions, such as
		93	C<scale>:
		94
		95	scale load "$HOME/mypic.png"
		96
		97	Just like a mathematical expression with functions, you should read these
		98	expressions from right to left, as the C<load> is evaluated first, and
		99	its result becomes the argument to the C<scale> function.
		100
		101	Many operators also allow some parameters preceding the input image
		102	that modify its behaviour. For example, C<scale> without any additional
		103	arguments scales the image to size of the terminal window. If you specify
		104	an additional argument, it uses it as a scale factor (multiply by 100 to
		105	get a percentage):
		106
		107	scale 2, load "$HOME/mypic.png"
		108
		109	This enlarges the image by a factor of 2 (200%). As you can see, C<scale>
		110	has now two arguments, the C<200> and the C<load> expression, while
		111	C<load> only has one argument. Arguments are separated from each other by
		112	commas.
		113
		114	Scale also accepts two arguments, which are then separate factors for both
		115	horizontal and vertical dimensions. For example, this halves the image
		116	width and doubles the image height:
		117
		118	scale 0.5, 2, load "$HOME/mypic.png"
		119
		120	Other effects than scaling are also readily available, for example, you can
		121	tile the image to fill the whole window, instead of resizing it:
		122
		123	tile load "$HOME/mypic.png"
		124
		125	In fact, images returned by C<load> are in C<tile> mode by default, so the C<tile> operator
		126	is kind of superfluous.
		127
		128	Another common effect is to mirror the image, so that the same edges touch:
		129
		130	mirror load "$HOME/mypic.png"
		131
		132	This is also a typical background expression:
		133
		134	rootalign root
		135
		136	It 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
		138	pseudo-transparency, as the image seems to be static while the window is
		139	moved around.
		140
		141	=head2 CYCLES AND CACHING
		142
		143	As has been mentioned before, the expression might be evaluated multiple
		144	times. Each time the expression is reevaluated, a new cycle is said to
		145	have begun. Many operators cache their results till the next cycle.
		146
		147	For example, the C<load> operator keeps a copy of the image. If it is
		148	asked to load the same image on the next cycle it will not load it again,
		149	but return the cached copy.
		150
		151	This only works for one cycle though, so as long as you load the same
		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
		155	This allows you to either speed things up by keeping multiple images in
		156	memory, or conserve memory by loading images more often.
		157
		158	For example, you can keep two images in memory and use a random one like
		159	this:
		160
		161	my $img1 = load "img1.png";
		162	my $img2 = load "img2.png";
		163	(0.5 > rand) ? $img1 : $img2
		164
		165	Since both images are "loaded" every time the expression is evaluated,
		166	they are always kept in memory. Contrast this version:
		167
		168	my $path1 = "img1.png";
		169	my $path2 = "img2.png";
		170	load ((0.5 > rand) ? $path1 : $path2)
		171
		172	Here, a path is selected randomly, and load is only called for one image,
		173	so keeps only one image in memory. If, on the next evaluation, luck
		174	decides to use the other path, then it will have to load that image again.
		175
		176	=head1 REFERENCE
		177
		178	=head2 COMMAND LINE SWITCHES
		179
		180	=over 4
		181
		182	=item --background-expr perl-expression
		183
		184	Specifies the Perl expression to evaluate.
		185
		186	=item --background-border
		187
		188	By default, the expression creates an image that fills the full window,
		189	overwriting borders and any other areas, such as the scrollbar.
		190
		191	Specifying this flag changes the behaviour, so that the image only
		192	replaces the background of the character area.
		193
		194	=item --background-interval seconds
		195
		196	Since some operations in the underlying XRender extension can effectively
		197	freeze your X-server for prolonged time, this extension enforces a minimum
		198	time between updates, which is normally about 0.1 seconds.
		199
		200	If you want to do updates more often, you can decrease this safety
		201	interval with this switch.
		202
		203	=back
		204
		205	=cut
		206
		207	our %_IMG_CACHE;
		208	our $HOME;
10	our ($bgdsl_self, $old, $new);	209	our ($self, $old, $new);
11	our ($l, $t, $w, $h);	210	our ($x, $y, $w, $h);
		211
		212	# enforce at least this interval between updates
		213	our $MIN_INTERVAL = 6/59.951;
12		214
13	{	215	{
14	package urxvt::bgdsl; # background language	216	package urxvt::bgdsl; # background language
15		217
16	*repeat_black = \&urxvt::RepeatNone; #TODO wtf	218	use List::Util qw(min max sum shuffle);
17	*repeat_wrap = \&urxvt::RepeatNormal;	219
18	*repeat_pad = \&urxvt::RepeatPad;	220	=head2 PROVIDERS/GENERATORS
19	*repeat_mirror = \&urxvt::RepeatReflect;	221
		222	These functions provide an image, by loading it from disk, grabbing it
		223	from the root screen or by simply generating it. They are used as starting
		224	points to get an image you can play with.
		225
		226	=over 4
		227
		228	=item load $path
		229
		230	Loads the image at the given C<$path>. The image is set to plane tiling
		231	mode.
		232
		233	Loaded images will be cached for one cycle, and shared between temrinals
		234	running in the same process (e.g. in C<urxvtd>).
		235
		236	=item load_uc $path
		237
		238	Load uncached - same as load, but does not cache the image. This function
		239	is most useufl if you want to optimise a background expression in some
		240	way.
		241
		242	=cut
		243
		244	sub load_uc($) {
		245	my ($path) = @_;
		246
		247	$_IMG_CACHE{$path} \|\| do {
		248	my $img = $self->new_img_from_file ($path);
		249	Scalar::Util::weaken ($_IMG_CACHE{$path} = $img);
		250	$img
		251	}
		252	}
20		253
21	sub load($) {	254	sub load($) {
22	my ($path) = @_;	255	my ($path) = @_;
23		256
24	$new->{load}{$path} = $old->{load}{$path} \|\| $bgdsl_self->new_img_from_file ($path);	257	$new->{load}{$path} = $old->{load}{$path} \|\| load_uc $path;
25	}	258	}
		259
		260	=item root
		261
		262	Returns the root window pixmap, that is, hopefully, the background image
		263	of your screen. The image is set to extend mode.
		264
		265	This function makes your expression root sensitive, that means it will be
		266	reevaluated when the bg image changes.
		267
		268	=cut
26		269
27	sub root() {	270	sub root() {
28	die "root op not supported, exg, we need you";	271	$new->{again}{rootpmap} = 1;
		272	$self->new_img_from_root
		273	}
		274
		275	=item solid $colour
		276
		277	=item solid $width, $height, $colour
		278
		279	Creates a new image and completely fills it with the given colour. The
		280	image is set to tiling mode.
		281
		282	If C<$width> and C<$height> are omitted, it creates a 1x1 image, which is
		283	useful for solid backgrounds or for use in filtering effects.
		284
		285	=cut
		286
		287	sub solid($;$$) {
		288	my $colour = pop;
		289
		290	my $img = $self->new_img (urxvt::PictStandardARGB32, $_[0] \|\| 1, $_[1] \|\| 1);
		291	$img->fill ($colour);
		292	$img
		293	}
		294
		295	=item clone $img
		296
		297	Returns an exact copy of the image. This is useful if you want to have
		298	multiple copies of the same image to apply different effects to.
		299
		300	=cut
		301
		302	sub clone($) {
		303	$_[0]->clone
		304	}
		305
		306	=head2 TILING MODES
		307
		308	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.
		310
		311	=over 4
		312
		313	=item tile $img
		314
		315	Tiles the whole plane with the image and returns this new image - or in
		316	other words, it returns a copy of the image in plane tiling mode.
		317
		318	Example: load an image and tile it over the background, without
		319	resizing. The C<tile> call is superfluous because C<load> already defaults
		320	to tiling mode.
		321
		322	tile load "mybg.png"
		323
		324	=item mirror $img
		325
		326	Similar to tile, but reflects the image each time it uses a new copy, so
		327	that top edges always touch top edges, right edges always touch right
		328	edges and so on (with normal tiling, left edges always touch right edges
		329	and top always touch bottom edges).
		330
		331	Example: load an image and mirror it over the background, avoiding sharp
		332	edges at the image borders at the expense of mirroring the image itself
		333
		334	mirror load "mybg.png"
		335
		336	=item pad $img
		337
		338	Takes an image and modifies it so that all pixels outside the image area
		339	become transparent. This mode is most useful when you want to place an
		340	image over another image or the background colour while leaving all
		341	background pixels outside the image unchanged.
		342
		343	Example: load an image and display it in the upper left corner. The rest
		344	of the space is left "empty" (transparent or whatever your compositor does
		345	in alpha mode, else background colour).
		346
		347	pad load "mybg.png"
		348
		349	=item extend $img
		350
		351	Extends the image over the whole plane, using the closest pixel in the
		352	area outside the image. This mode is mostly useful when you use more complex
		353	filtering operations and want the pixels outside the image to have the
		354	same values as the pixels near the edge.
		355
		356	Example: just for curiosity, how does this pixel extension stuff work?
		357
		358	extend move 50, 50, load "mybg.png"
		359
		360	=cut
		361
		362	sub pad($) {
		363	my $img = $_[0]->clone;
		364	$img->repeat_mode (urxvt::RepeatNone);
		365	$img
		366	}
		367
		368	sub tile($) {
		369	my $img = $_[0]->clone;
		370	$img->repeat_mode (urxvt::RepeatNormal);
		371	$img
		372	}
		373
		374	sub mirror($) {
		375	my $img = $_[0]->clone;
		376	$img->repeat_mode (urxvt::RepeatReflect);
		377	$img
		378	}
		379
		380	sub extend($) {
		381	my $img = $_[0]->clone;
		382	$img->repeat_mode (urxvt::RepeatPad);
		383	$img
		384	}
		385
		386	=back
		387
		388	=head2 VARIABLE VALUES
		389
		390	The following functions provide variable data such as the terminal window
		391	dimensions. They are not (Perl-) variables, they just return stuff that
		392	varies. Most of them make your expression sensitive to some events, for
		393	example using C<TW> (terminal width) means your expression is evaluated
		394	again when the terminal is resized.
		395
		396	=over 4
		397
		398	=item TX
		399
		400	=item TY
		401
		402	Return the X and Y coordinates of the terminal window (the terminal
		403	window is the full window by default, and the character area only when in
		404	border-respect mode).
		405
		406	Using these functions make your expression sensitive to window moves.
		407
		408	These functions are mainly useful to align images to the root window.
		409
		410	Example: load an image and align it so it looks as if anchored to the
		411	background.
		412
		413	move -TX, -TY, load "mybg.png"
		414
		415	=item TW
		416
		417	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
		419	when in border-respect mode).
		420
		421	Using these functions make your expression sensitive to window resizes.
		422
		423	These functions are mainly useful to scale images, or to clip images to
		424	the window size to conserve memory.
		425
		426	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.
		428
		429	clip move -TX, -TY, once { blur 5, root }
		430
		431	=cut
		432
		433	sub TX() { $new->{again}{position} = 1; $x }
		434	sub TY() { $new->{again}{position} = 1; $y }
		435	sub TW() { $new->{again}{size} = 1; $w }
		436	sub TH() { $new->{again}{size} = 1; $h }
		437
		438	=item now
		439
		440	Returns the current time as (fractional) seconds since the epoch.
		441
		442	Using this expression does I<not> make your expression sensitive to time,
		443	but the next two functions do.
		444
		445	=item again $seconds
		446
		447	When this function is used the expression will be reevaluated again in
		448	C<$seconds> seconds.
		449
		450	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.
		452
		453	again 60; rotate 50, 50, (now % 86400) * -720 / 86400, scale load "myclock.png"
		454
		455	=item counter $seconds
		456
		457	Like C<again>, but also returns an increasing counter value, starting at
		458	0, which might be useful for some simple animation effects.
		459
		460	=cut
		461
		462	sub now() { urxvt::NOW }
		463
		464	sub again($) {
		465	$new->{again}{time} = $_[0];
		466	}
		467
		468	sub counter($) {
		469	$new->{again}{time} = $_[0];
		470	$self->{counter} + 0
		471	}
		472
		473	=back
		474
		475	=head2 SHAPE CHANGING OPERATORS
		476
		477	The following operators modify the shape, size or position of the image.
		478
		479	=over 4
		480
		481	=item clip $img
		482
		483	=item clip $width, $height, $img
		484
		485	=item clip $x, $y, $width, $height, $img
		486
		487	Clips an image to the given rectangle. If the rectangle is outside the
		488	image area (e.g. when C<$x> or C<$y> are negative) or the rectangle is
		489	larger than the image, then the tiling mode defines how the extra pixels
		490	will be filled.
		491
		492	If C<$x> an C<$y> are missing, then C<0> is assumed for both.
		493
		494	If C<$width> and C<$height> are missing, then the window size will be
		495	assumed.
		496
		497	Example: load an image, blur it, and clip it to the window size to save
		498	memory.
		499
		500	clip blur 10, load "mybg.png"
		501
		502	=cut
		503
		504	sub clip($;$$;$$) {
		505	my $img = pop;
		506	my $h = pop \|\| TH;
		507	my $w = pop \|\| TW;
		508	$img->sub_rect ($_[0], $_[1], $w, $h)
		509	}
		510
		511	=item scale $img
		512
		513	=item scale $size_factor, $img
		514
		515	=item scale $width_factor, $height_factor, $img
		516
		517	Scales the image by the given factors in horizontal
		518	(C<$width>) and vertical (C<$height>) direction.
		519
		520	If only one factor is give, it is used for both directions.
		521
		522	If no factors are given, scales the image to the window size without
		523	keeping aspect.
		524
		525	=item resize $width, $height, $img
		526
		527	Resizes the image to exactly C<$width> times C<$height> pixels.
		528
		529	=item fit $img
		530
		531	=item fit $width, $height, $img
		532
		533	Fits the image into the given C<$width> and C<$height> without changing
		534	aspect, or the terminal size. That means it will be shrunk or grown until
		535	the whole image fits into the given area, possibly leaving borders.
		536
		537	=item cover $img
		538
		539	=item cover $width, $height, $img
		540
		541	Similar to C<fit>, but shrinks or grows until all of the area is covered
		542	by the image, so instead of potentially leaving borders, it will cut off
		543	image data that doesn't fit.
		544
		545	=cut
		546
		547	sub scale($;$;$) {
		548	my $img = pop;
		549
		550	@_ == 2 ? $img->scale ($_[0] * $img->w, $_[1] * $img->h)
		551	: @_ ? $img->scale ($_[0] * $img->w, $_[0] * $img->h)
		552	: $img->scale (TW, TH)
29	}	553	}
30		554
31	sub resize($$$) {	555	sub resize($$$) {
32	$_[0]->scale ($_[1], $_[2])	556	my $img = pop;
		557	$img->scale ($_[0], $_[1])
33	}	558	}
34		559
		560	sub fit($;$$) {
		561	my $img = pop;
		562	my $w = ($_[0] \|\| TW) / $img->w;
		563	my $h = ($_[1] \|\| TH) / $img->h;
		564	scale +(min $w, $h), $img
		565	}
		566
		567	sub cover($;$$) {
		568	my $img = pop;
		569	my $w = ($_[0] \|\| TW) / $img->w;
		570	my $h = ($_[1] \|\| TH) / $img->h;
		571	scale +(max $w, $h), $img
		572	}
		573
		574	=item move $dx, $dy, $img
		575
		576	Moves the image by C<$dx> pixels in the horizontal, and C<$dy> pixels in
		577	the vertical.
		578
		579	Example: move the image right by 20 pixels and down by 30.
		580
		581	move 20, 30, ...
		582
		583	=item align $xalign, $yalign, $img
		584
		585	Aligns the image according to a factor - C<0> means the image is moved to
		586	the left or top edge (for C<$xalign> or C<$yalign>), C<0.5> means it is
		587	exactly centered and C<1> means it touches the right or bottom edge.
		588
		589	Example: remove any visible border around an image, center it vertically but move
		590	it to the right hand side.
		591
		592	align 1, 0.5, pad $img
		593
		594	=item center $img
		595
		596	=item center $width, $height, $img
		597
		598	Centers the image, i.e. the center of the image is moved to the center of
		599	the terminal window (or the box specified by C<$width> and C<$height> if
		600	given).
		601
		602	Example: load an image and center it.
		603
		604	center pad load "mybg.png"
		605
		606	=item rootalign $img
		607
		608	Moves the image so that it appears glued to the screen as opposed to the
		609	window. This gives the illusion of a larger area behind the window. It is
		610	exactly equivalent to C<move -TX, -TY>, that is, it moves the image to the
		611	top left of the screen.
		612
		613	Example: load a background image, put it in mirror mode and root align it.
		614
		615	rootalign mirror load "mybg.png"
		616
		617	Example: take the screen background and align it, giving the illusion of
		618	transparency as long as the window isn't in front of other windows.
		619
		620	rootalign root
		621
		622	=cut
		623
35	sub move($$$) {	624	sub move($$;$) {
36	# TODO: must be simpler	625	my $img = pop->clone;
37	$_[0]->transform ($_[0]->w, $_[0]->h, $_[1],	626	$img->move ($_[0], $_[1]);
38	1, 0, -$_[2],	627	$img
39	0, 1, -$_[3],	628	}
40	0, 0, 1,	629
		630	sub align($;$$) {
		631	my $img = pop;
		632
		633	move $_[0] * (TW - $img->w),
		634	$_[1] * (TH - $img->h),
		635	$img
		636	}
		637
		638	sub center($;$$) {
		639	my $img = pop;
		640	my $w = $_[0] \|\| TW;
		641	my $h = $_[1] \|\| TH;
		642
		643	move 0.5 * ($w - $img->w), 0.5 * ($h - $img->h), $img
		644	}
		645
		646	sub rootalign($) {
		647	move -TX, -TY, $_[0]
		648	}
		649
		650	=item rotate $center_x, $center_y, $degrees
		651
		652	Rotates the image by C<$degrees> degrees, counter-clockwise, around the
		653	pointer at C<$center_x> and C<$center_y> (specified as factor of image
		654	width/height).
		655
		656	#TODO# new width, height, maybe more operators?
		657
		658	Example: rotate the image by 90 degrees
		659
		660	=cut
		661
		662	sub rotate($$$$) {
		663	my $img = pop;
		664	$img->rotate (
		665	$_[0] * $img->w,
		666	$_[1] * $img->h,
		667	$_[2] * (3.14159265 / 180),
41	)	668	)
42	}	669	}
43		670
44	sub rotate($$$$) {	671	=back
45	$_[0]->rotate ($_[0], $_[1], $_[2], $_[3] * (3.14159265 / 180))
46	}
47		672
48	sub blur($$$) {	673	=head2 COLOUR MODIFICATIONS
49	my ($img, $rh, $rv) = @_;
50		674
51	$img = $img->clone;	675	The following operators change the pixels of the image.
52	$img->clone->blur ($rh, $rv);	676
53	$img	677	=over 4
54	}	678
		679	=item contrast $factor, $img
		680
		681	=item contrast $r, $g, $b, $img
		682
		683	=item contrast $r, $g, $b, $a, $img
		684
		685	Adjusts the I<contrast> of an image.
		686
		687	The first form applies a single C<$factor> to red, green and blue, the
		688	second form applies separate factors to each colour channel, and the last
		689	form includes the alpha channel.
		690
		691	Values from 0 to 1 lower the contrast, values higher than 1 increase the
		692	contrast.
		693
		694	Due to limitations in the underlying XRender extension, lowering contrast
		695	also reduces brightness, while increasing contrast currently also
		696	increases brightness.
		697
		698	=item brightness $bias, $img
		699
		700	=item brightness $r, $g, $b, $img
		701
		702	=item brightness $r, $g, $b, $a, $img
		703
		704	Adjusts the brightness of an image.
		705
		706	The first form applies a single C<$bias> to red, green and blue, the
		707	second form applies separate biases to each colour channel, and the last
		708	form includes the alpha channel.
		709
		710	Values less than 0 reduce brightness, while values larger than 0 increase
		711	it. Useful range is from -1 to 1 - the former results in a black, the
		712	latter in a white picture.
		713
		714	Due to idiosyncrasies in the underlying XRender extension, biases less
		715	than zero can be I<very> slow.
		716
		717	=cut
55		718
56	sub contrast($$;$$;$) {	719	sub contrast($$;$$;$) {
		720	my $img = pop;
57	my ($img, $r, $g, $b, $a) = @_;	721	my ($r, $g, $b, $a) = @_;
		722
58	($g, $b) = ($r, $r) if @_ < 4;	723	($g, $b) = ($r, $r) if @_ < 3;
59	$a = 1 if @_ < 5;	724	$a = 1 if @_ < 4;
		725
60	$img = $img->clone;	726	$img = $img->clone;
61	$img->contrast ($r, $g, $b, $a);	727	$img->contrast ($r, $g, $b, $a);
62	$img	728	$img
63	}	729	}
64		730
65	sub brightness($$;$$;$) {	731	sub brightness($$;$$;$) {
		732	my $img = pop;
66	my ($img, $r, $g, $b, $a) = @_;	733	my ($r, $g, $b, $a) = @_;
		734
67	($g, $b) = ($r, $r) if @_ < 4;	735	($g, $b) = ($r, $r) if @_ < 3;
68	$a = 1 if @_ < 5;	736	$a = 1 if @_ < 4;
		737
69	$img = $img->clone;	738	$img = $img->clone;
70	$img->brightness ($r, $g, $b, $a);	739	$img->brightness ($r, $g, $b, $a);
71	$img	740	$img
72	}	741	}
73		742
74	sub left () { $new->{position_sensitive} = 1; $l }	743	=item blur $radius, $img
75	sub top () { $new->{position_sensitive} = 1; $t }
76	sub width () { $new->{size_sensitive} = 1; $w }
77	sub height() { $new->{size_sensitive} = 1; $h }
78		744
79	sub now() { urxvt::NOW }	745	=item blur $radius_horz, $radius_vert, $img
80		746
81	sub again($) {	747	Gaussian-blurs the image with (roughly) C<$radius> pixel radius. The radii
		748	can also be specified separately.
		749
		750	Blurring is often I<very> slow, at least compared or other
		751	operators. Larger blur radii are slower than smaller ones, too, so if you
		752	don't want to freeze your screen for long times, start experimenting with
		753	low values for radius (<5).
		754
		755	=cut
		756
		757	sub blur($$;$) {
		758	my $img = pop;
		759	$img->blur ($_[0], @_ >= 2 ? $_[1] : $_[0])
		760	}
		761
		762	=back
		763
		764	=head2 OTHER STUFF
		765
		766	Anything that didn't fit any of the other categories, even after appliyng
		767	force and closing our eyes.
		768
		769	=over 4
		770
		771	=item once { ... }
		772
		773	This function takes a code block as argument, that is, one or more
		774	statements enclosed by braces.
		775
		776	The trick is that this code block is only evaluated once - future calls
		777	will simply return the original image (yes, it should only be used with
		778	images).
		779
		780	This can be extremely useful to avoid redoign the same slow operations
		781	again and again- for example, if your background expression takes the root
		782	background, blurs it and then root-aligns it it would have to blur the
		783	root background on every window move or resize.
		784
		785	Putting the blur into a C<once> block will make sure the blur is only done
		786	once:
		787
		788	rootlign once { blur 10, root }
		789
		790	This leaves the question of how to force reevaluation of the block, in
		791	case the root background changes: Right now, all once blocks forget that
		792	they ahve been executed before each time the root background changes (if
		793	the expression is sensitive to that) or when C<once_again> is called.
		794
		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
		801
		802	sub once(&) {
		803	my $once = $self->{once_cache}{$_[0]+0} \|\|= do {
		804	local $new->{again};
		805	my @res = $_[0]();
		806	[$new->{again}, \@res]
		807	};
		808
82	$new->{again} = $_[0];	809	$new->{again} = {
83	}	810	%{ $new->{again} },
		811	%{ $once->[0] }
		812	};
84		813
85	sub counter($) {	814	# in scalar context we always return the first original result, which
86	$new->{again} = $_[0];	815	# is not quite how perl works.
87	$bgdsl_self->{counter}++ + 0	816	wantarray
		817	? @{ $once->[1] }
		818	: $once->[1][0]
88	}	819	}
		820
		821	sub once_again() {
		822	delete $self->{once_cache};
		823	}
		824
		825	=back
		826
		827	=cut
		828
89	}	829	}
90		830
91	sub parse_expr {	831	sub parse_expr {
92	my $expr = eval "sub {\npackage urxvt::bgdsl;\n#line 0 'background expression'\n$_[0]\n}";	832	my $expr = eval "sub {\npackage urxvt::bgdsl;\n#line 0 'background expression'\n$_[0]\n}";
93	die if $@;	833	die if $@;
96		836
97	# compiles a parsed expression	837	# compiles a parsed expression
98	sub set_expr {	838	sub set_expr {
99	my ($self, $expr) = @_;	839	my ($self, $expr) = @_;
100		840
101	local $Data::Dumper::Deparse=1; use Data::Dumper; warn Dumper $expr;#d#
102	$self->{expr} = $expr;	841	$self->{expr} = $expr;
103	$self->recalculate;	842	$self->recalculate;
104	}	843	}
105		844
106	# evaluate the current bg expression	845	# evaluate the current bg expression
107	sub recalculate {	846	sub recalculate {
108	my ($self) = @_;	847	my ($arg_self) = @_;
109		848
110	local $bgdsl_self = $self;	849	# rate limit evaluation
111		850
		851	if ($arg_self->{next_refresh} > urxvt::NOW) {
		852	$arg_self->{next_refresh_timer} = urxvt::timer->new->after ($arg_self->{next_refresh} - urxvt::NOW)->cb (sub {
		853	$arg_self->recalculate;
		854	});
		855	return;
		856	}
		857
		858	$arg_self->{next_refresh} = urxvt::NOW + $MIN_INTERVAL;
		859
		860	# set environment to evaluate user expression
		861
		862	local $self = $arg_self;
		863
		864	local $HOME = $ENV{HOME};
112	local $old = $self->{state};	865	local $old = $self->{state};
113	local $new = my $state = $self->{state} = {};	866	local $new = my $state = $self->{state} = {};
114		867
115	($l, $t, $w, $h) =	868	($x, $y, $w, $h) =
116	$self->get_geometry;	869	$self->background_geometry ($self->{border});
117		870
118	warn "$l, $t";#d#	871	# evaluate user expression
119		872
120	my $img = eval { $self->{expr}->() };	873	my $img = eval { $self->{expr}->() };
121	warn $@ if $@;#d#	874	warn $@ if $@;#d#
		875	die "background-expr did not return an image.\n" if !UNIVERSAL::isa $img, "urxvt::img";
122		876
123	my $repeat;	877	# if the expression is sensitive to external events, prepare reevaluation then
124		878
125	if (my $again = $state->{again}) {	879	my $again = delete $state->{again};
126	$repeat = 1;
127	$state->{again} = urxvt::timer->new->after ($again)->cb (sub { $self->recalculate });
128	}
129		880
130	if (delete $state->{position_sensitive}) {	881	$again->{size} = 1
131	$repeat = 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}) {
132	$self->enable (position_change => sub { $_[0]->recalculate });	895	$self->enable (position_change => sub { $_[0]->recalculate });
133	} else {	896	} else {
134	$self->disable ("position_change");	897	$self->disable ("position_change");
135	}	898	}
136		899
137	if (delete $state->{size_sensitive}) {	900	if ($again->{size}) {
138	$repeat = 1;
139	$self->enable (size_change => sub { $_[0]->recalculate });	901	$self->enable (size_change => sub { $_[0]->recalculate });
140	} else {	902	} else {
141	$self->disable ("size_change");	903	$self->disable ("size_change");
142	}	904	}
143		905
144	# TODO: install handlers for geometry changes &c	906	if ($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	}
145		914
146	warn $img;	915	# clear stuff we no longer need
		916
		917	%$old = ();
		918
		919	unless (%$again) {
		920	delete $self->{state};
		921	delete $self->{expr};
		922	}
		923
		924	# set background pixmap
		925
147	$self->set_background ($img);	926	$self->set_background ($img, $self->{border});
148	$self->scr_recolour (0);	927	$self->scr_recolour (0);
149	$self->want_refresh;	928	$self->want_refresh;
150	}	929	}
151		930
152	sub on_start {	931	sub on_start {
153	my ($self) = @_;	932	my ($self) = @_;
154		933
		934	my $expr = $self->x_resource ("%.expr")
		935	or return;
		936
		937	$self->has_render
		938	or die "background extension needs RENDER extension 0.10 or higher, ignoring background-expr.\n";
		939
155	$self->set_expr (parse_expr $EXPR);	940	$self->set_expr (parse_expr $expr);
		941	$self->{border} = $self->x_resource_boolean ("%.border");
		942
		943	$MIN_INTERVAL = $self->x_resource ("%.interval");
156		944
157	()	945	()
158	}	946	}
159		947

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Comparing rxvt-unicode/src/perl/background (file contents): Revision 1.3 by root, Tue Jun 5 12:08:23 2012 UTC vs. Revision 1.55 by root, Thu Jun 14 16:48:57 2012 UTC

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Comparing rxvt-unicode/src/perl/background (file contents):
Revision 1.3 by root, Tue Jun 5 12:08:23 2012 UTC vs.
Revision 1.55 by root, Thu Jun 14 16:48:57 2012 UTC