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

Comparing rxvt-unicode/src/perl/background (file contents):
Revision 1.13 by root, Tue Jun 5 19:32:29 2012 UTC vs.
Revision 1.52 by root, Tue Jun 12 10:45:53 2012 UTC

…		…
1	#! perl	1	#! perl
2		2
3	#:META:RESOURCE:$$:string:background expression	3	#:META:X_RESOURCE:%.expr:string:background expression
		4	#:META:X_RESOURCE:%.border:boolean:respect the terminal border
		5	#:META:X_RESOURCE:%.interval:seconds:minimum time between updates
4		6
5	our $EXPR = 'move load "/root/pix/das_fette_schwein.jpg", repeat_wrap, X, Y';	7	=head1 NAME
6	$EXPR = '
7	rotate W, H, 50, 50, counter 1/59.95, repeat_mirror,
8	clip X, Y, W, H, repeat_mirror,
9	load "/root/pix/das_fette_schwein.jpg"
10	';
11	#$EXPR = 'blur root, 10, 10'
12	#$EXPR = 'blur move (root, -x, -y), 5, 5'
13	#resize load "/root/pix/das_fette_schwein.jpg", w, h
14		8
15	use Safe;	9	background - manage terminal background
16		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 gets 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 %_ONCE_CACHE;
		209	our $HOME;
17	our ($bgdsl_self, $old, $new);	210	our ($self, $old, $new);
18	our ($l, $t, $w, $h);	211	our ($x, $y, $w, $h);
19		212
20	# enforce at leats this time between updates	213	# enforce at least this interval between updates
21	our $MIN_INTERVAL = 1/100;	214	our $MIN_INTERVAL = 6/59.951;
22		215
23	{	216	{
24	package urxvt::bgdsl; # background language	217	package urxvt::bgdsl; # background language
25		218
26	*repeat_black = \&urxvt::RepeatNone; #TODO wtf	219	use List::Util qw(min max sum shuffle);
27	*repeat_wrap = \&urxvt::RepeatNormal;	220
28	*repeat_pad = \&urxvt::RepeatPad;	221	=head2 PROVIDERS/GENERATORS
29	*repeat_mirror = \&urxvt::RepeatReflect;	222
		223	These functions provide an image, by loading it from disk, grabbing it
		224	from the root screen or by simply generating it. They are used as starting
		225	points to get an image you can play with.
		226
		227	=over 4
		228
		229	=item load $path
		230
		231	Loads the image at the given C<$path>. The image is set to plane tiling
		232	mode.
		233
		234	Loaded images will be cached for one cycle.
		235
		236	=cut
30		237
31	sub load($) {	238	sub load($) {
32	my ($path) = @_;	239	my ($path) = @_;
33		240
34	$new->{load}{$path} = $old->{load}{$path} \|\| $bgdsl_self->new_img_from_file ($path);	241	$new->{load}{$path} = $old->{load}{$path} \|\| $self->new_img_from_file ($path);
35	}	242	}
		243
		244	=item root
		245
		246	Returns the root window pixmap, that is, hopefully, the background image
		247	of your screen. The image is set to extend mode.
		248
		249	This function makes your expression root sensitive, that means it will be
		250	reevaluated when the bg image changes.
		251
		252	=cut
36		253
37	sub root() {	254	sub root() {
38	$new->{rootpmap_sensitive} = 1;	255	$new->{rootpmap_sensitive} = 1;
39	die "root op not supported, exg, we need you";	256	$self->new_img_from_root
40	}	257	}
41		258
		259	=item solid $colour
		260
		261	=item solid $width, $height, $colour
		262
		263	Creates a new image and completely fills it with the given colour. The
		264	image is set to tiling mode.
		265
		266	If C<$width> and C<$height> are omitted, it creates a 1x1 image, which is
		267	useful for solid backgrounds or for use in filtering effects.
		268
		269	=cut
		270
		271	sub solid($;$$) {
		272	my $colour = pop;
		273
		274	my $img = $self->new_img (urxvt::PictStandardARGB32, $_[0] \|\| 1, $_[1] \|\| 1);
		275	$img->fill ($colour);
		276	$img
		277	}
		278
		279	=item clone $img
		280
		281	Returns an exact copy of the image. This is useful if you want to have
		282	multiple copies of the same image to apply different effects to.
		283
		284	=cut
		285
42	# sub clone($) {	286	sub clone($) {
43	# $_[0]->clone	287	$_[0]->clone
44	# }	288	}
45		289
		290	=head2 TILING MODES
		291
		292	The following operators modify the tiling mode of an image, that is, the
		293	way that pixels outside the image area are painted when the image is used.
		294
		295	=over 4
		296
		297	=item tile $img
		298
		299	Tiles the whole plane with the image and returns this new image - or in
		300	other words, it returns a copy of the image in plane tiling mode.
		301
		302	Example: load an image and tile it over the background, without
		303	resizing. The C<tile> call is superfluous because C<load> already defaults
		304	to tiling mode.
		305
		306	tile load "mybg.png"
		307
		308	=item mirror $img
		309
		310	Similar to tile, but reflects the image each time it uses a new copy, so
		311	that top edges always touch top edges, right edges always touch right
		312	edges and so on (with normal tiling, left edges always touch right edges
		313	and top always touch bottom edges).
		314
		315	Example: load an image and mirror it over the background, avoiding sharp
		316	edges at the image borders at the expense of mirroring the image itself
		317
		318	mirror load "mybg.png"
		319
		320	=item pad $img
		321
		322	Takes an image and modifies it so that all pixels outside the image area
		323	become transparent. This mode is most useful when you want to place an
		324	image over another image or the background colour while leaving all
		325	background pixels outside the image unchanged.
		326
		327	Example: load an image and display it in the upper left corner. The rest
		328	of the space is left "empty" (transparent or whatever your compositor does
		329	in alpha mode, else background colour).
		330
		331	pad load "mybg.png"
		332
		333	=item extend $img
		334
		335	Extends the image over the whole plane, using the closest pixel in the
		336	area outside the image. This mode is mostly useful when you use more complex
		337	filtering operations and want the pixels outside the image to have the
		338	same values as the pixels near the edge.
		339
		340	Example: just for curiosity, how does this pixel extension stuff work?
		341
		342	extend move 50, 50, load "mybg.png"
		343
		344	=cut
		345
		346	sub pad($) {
		347	my $img = $_[0]->clone;
		348	$img->repeat_mode (urxvt::RepeatNone);
		349	$img
		350	}
		351
		352	sub tile($) {
		353	my $img = $_[0]->clone;
		354	$img->repeat_mode (urxvt::RepeatNormal);
		355	$img
		356	}
		357
		358	sub mirror($) {
		359	my $img = $_[0]->clone;
		360	$img->repeat_mode (urxvt::RepeatReflect);
		361	$img
		362	}
		363
		364	sub extend($) {
		365	my $img = $_[0]->clone;
		366	$img->repeat_mode (urxvt::RepeatPad);
		367	$img
		368	}
		369
		370	=back
		371
		372	=head2 VARIABLE VALUES
		373
		374	The following functions provide variable data such as the terminal window
		375	dimensions. They are not (Perl-) variables, they just return stuff that
		376	varies. Most of them make your expression sensitive to some events, for
		377	example using C<TW> (terminal width) means your expression is evaluated
		378	again when the terminal is resized.
		379
		380	=over 4
		381
		382	=item TX
		383
		384	=item TY
		385
		386	Return the X and Y coordinates of the terminal window (the terminal
		387	window is the full window by default, and the character area only when in
		388	border-respect mode).
		389
		390	Using these functions make your expression sensitive to window moves.
		391
		392	These functions are mainly useful to align images to the root window.
		393
		394	Example: load an image and align it so it looks as if anchored to the
		395	background.
		396
		397	move -TX, -TY, load "mybg.png"
		398
		399	=item TW
		400
		401	Return the width (C<TW>) and height (C<TH>) of the terminal window (the
		402	terminal window is the full window by default, and the character area only
		403	when in border-respect mode).
		404
		405	Using these functions make your expression sensitive to window resizes.
		406
		407	These functions are mainly useful to scale images, or to clip images to
		408	the window size to conserve memory.
		409
		410	Example: take the screen background, clip it to the window size, blur it a
		411	bit, align it to the window position and use it as background.
		412
		413	clip move -TX, -TY, blur 5, root
		414
		415	=cut
		416
		417	sub TX() { $new->{position_sensitive} = 1; $x }
		418	sub TY() { $new->{position_sensitive} = 1; $y }
		419	sub TW() { $new->{size_sensitive} = 1; $w }
		420	sub TH() { $new->{size_sensitive} = 1; $h }
		421
		422	=item now
		423
		424	Returns the current time as (fractional) seconds since the epoch.
		425
		426	Using this expression does I<not> make your expression sensitive to time,
		427	but the next two functions do.
		428
		429	=item again $seconds
		430
		431	When this function is used the expression will be reevaluated again in
		432	C<$seconds> seconds.
		433
		434	Example: load some image and rotate it according to the time of day (as if it were
		435	the hour pointer of a clock). Update this image every minute.
		436
		437	again 60; rotate TW, TH, 50, 50, (now % 86400) * -720 / 86400, scale load "myclock.png"
		438
		439	=item counter $seconds
		440
		441	Like C<again>, but also returns an increasing counter value, starting at
		442	0, which might be useful for some simple animation effects.
		443
		444	=cut
		445
		446	sub now() { urxvt::NOW }
		447
		448	sub again($) {
		449	$new->{again} = $_[0];
		450	}
		451
		452	sub counter($) {
		453	$new->{again} = $_[0];
		454	$self->{counter} + 0
		455	}
		456
		457	=back
		458
		459	=head2 SHAPE CHANGING OPERATORS
		460
		461	The following operators modify the shape, size or position of the image.
		462
		463	=over 4
		464
		465	=item clip $img
		466
		467	=item clip $width, $height, $img
		468
		469	=item clip $x, $y, $width, $height, $img
		470
		471	Clips an image to the given rectangle. If the rectangle is outside the
		472	image area (e.g. when C<$x> or C<$y> are negative) or the rectangle is
		473	larger than the image, then the tiling mode defines how the extra pixels
		474	will be filled.
		475
		476	If C<$x> an C<$y> are missing, then C<0> is assumed for both.
		477
		478	If C<$width> and C<$height> are missing, then the window size will be
		479	assumed.
		480
		481	Example: load an image, blur it, and clip it to the window size to save
		482	memory.
		483
		484	clip blur 10, load "mybg.png"
		485
		486	=cut
		487
46	sub clip($$$$$;$) {	488	sub clip($;$$;$$) {
		489	my $img = pop;
47	my $img = pop;	490	my $h = pop \|\| TH;
		491	my $w = pop \|\| TW;
48	$img->sub_rect ($_[0], $_[1], $_[2], $_[3], $_[4])	492	$img->sub_rect ($_[0], $_[1], $w, $h)
		493	}
		494
		495	=item scale $img
		496
		497	=item scale $size_factor, $img
		498
		499	=item scale $width_factor, $height_factor, $img
		500
		501	Scales the image by the given factors in horizontal
		502	(C<$width>) and vertical (C<$height>) direction.
		503
		504	If only one factor is give, it is used for both directions.
		505
		506	If no factors are given, scales the image to the window size without
		507	keeping aspect.
		508
		509	=item resize $width, $height, $img
		510
		511	Resizes the image to exactly C<$width> times C<$height> pixels.
		512
		513	=item fit $img
		514
		515	=item fit $width, $height, $img
		516
		517	Fits the image into the given C<$width> and C<$height> without changing
		518	aspect, or the terminal size. That means it will be shrunk or grown until
		519	the whole image fits into the given area, possibly leaving borders.
		520
		521	=item cover $img
		522
		523	=item cover $width, $height, $img
		524
		525	Similar to C<fit>, but shrinks or grows until all of the area is covered
		526	by the image, so instead of potentially leaving borders, it will cut off
		527	image data that doesn't fit.
		528
		529	=cut
		530
		531	sub scale($;$;$) {
		532	my $img = pop;
		533
		534	@_ == 2 ? $img->scale ($_[0] * $img->w, $_[1] * $img->h)
		535	: @_ ? $img->scale ($_[0] * $img->w, $_[0] * $img->h)
		536	: $img->scale (TW, TH)
49	}	537	}
50		538
51	sub resize($$$) {	539	sub resize($$$) {
52	my $img = pop;	540	my $img = pop;
53	$img->scale ($_[0], $_[1])	541	$img->scale ($_[0], $_[1])
54	}	542	}
55		543
56	# TODO: ugly	544	sub fit($;$$) {
		545	my $img = pop;
		546	my $w = ($_[0] \|\| TW) / $img->w;
		547	my $h = ($_[1] \|\| TH) / $img->h;
		548	scale +(min $w, $h), $img
		549	}
		550
		551	sub cover($;$$) {
		552	my $img = pop;
		553	my $w = ($_[0] \|\| TW) / $img->w;
		554	my $h = ($_[1] \|\| TH) / $img->h;
		555	scale +(max $w, $h), $img
		556	}
		557
		558	=item move $dx, $dy, $img
		559
		560	Moves the image by C<$dx> pixels in the horizontal, and C<$dy> pixels in
		561	the vertical.
		562
		563	Example: move the image right by 20 pixels and down by 30.
		564
		565	move 20, 30, ...
		566
		567	=item align $xalign, $yalign, $img
		568
		569	Aligns the image according to a factor - C<0> means the image is moved to
		570	the left or top edge (for C<$xalign> or C<$yalign>), C<0.5> means it is
		571	exactly centered and C<1> means it touches the right or bottom edge.
		572
		573	Example: remove any visible border around an image, center it vertically but move
		574	it to the right hand side.
		575
		576	align 1, 0.5, pad $img
		577
		578	=item center $img
		579
		580	=item center $width, $height, $img
		581
		582	Centers the image, i.e. the center of the image is moved to the center of
		583	the terminal window (or the box specified by C<$width> and C<$height> if
		584	given).
		585
		586	Example: load an image and center it.
		587
		588	center pad load "mybg.png"
		589
		590	=item rootalign $img
		591
		592	Moves the image so that it appears glued to the screen as opposed to the
		593	window. This gives the illusion of a larger area behind the window. It is
		594	exactly equivalent to C<move -TX, -TY>, that is, it moves the image to the
		595	top left of the screen.
		596
		597	Example: load a background image, put it in mirror mode and root align it.
		598
		599	rootalign mirror load "mybg.png"
		600
		601	Example: take the screen background and align it, giving the illusion of
		602	transparency as long as the window isn't in front of other windows.
		603
		604	rootalign root
		605
		606	=cut
		607
57	sub move($$;$) {	608	sub move($$;$) {
58	my $img = pop;	609	my $img = pop->clone;
		610	$img->move ($_[0], $_[1]);
		611	$img
		612	}
		613
		614	sub align($;$$) {
		615	my $img = pop;
		616
		617	move $_[0] * (TW - $img->w),
		618	$_[1] * (TH - $img->h),
		619	$img
		620	}
		621
		622	sub center($;$$) {
		623	my $img = pop;
		624	my $w = $_[0] \|\| TW;
		625	my $h = $_[1] \|\| TH;
		626
		627	move 0.5 * ($w - $img->w), 0.5 * ($h - $img->h), $img
		628	}
		629
		630	sub rootalign($) {
		631	move -TX, -TY, $_[0]
		632	}
		633
		634	=item rotate $center_x, $center_y, $degrees, $new_width, $new_height
		635
		636	Rotates the image by C<$degrees> degrees, counter-clockwise, around the
		637	pointer at C<$center_x> and C<$center_y> (specified as factor of image
		638	width/height), generating a new image with width C<$new_width> and height
		639	C<$new_height>.
		640
		641	#TODO# new width, height, maybe more operators?
		642
		643	Example: rotate the image by 90 degrees
		644
		645	=cut
		646
		647	sub rotate($$$$$$) {
		648	my $img = pop;
59	$img->sub_rect (	649	$img->rotate (
60	$_[0], $_[1],	650	$_[0] * $img->w,
61	$img->w, $img->h,	651	$_[1] * $img->h,
		652	$_[2] * (3.14159265 / 180),
62	$_[2],	653	$_[3],
		654	$_[4],
63	)	655	)
64	}	656	}
65		657
66	sub rotate($$$$$$;$) {	658	=back
67	my $img = pop;
68	$img->rotate (
69	$_[0],
70	$_[1],
71	$_[2] * $img->w * .01,
72	$_[3] * $img->h * .01,
73	$_[4] * (3.14159265 / 180),
74	$_[5],
75	)
76	}
77		659
78	sub blur($$$) {	660	=head2 COLOUR MODIFICATIONS
79	my ($rh, $rv, $img) = @_;
80		661
81	$img->blur ($rh, $rv);	662	The following operators change the pixels of the image.
82	}	663
		664	=over 4
		665
		666	=item contrast $factor, $img
		667
		668	=item contrast $r, $g, $b, $img
		669
		670	=item contrast $r, $g, $b, $a, $img
		671
		672	Adjusts the I<contrast> of an image.
		673
		674	The first form applies a single C<$factor> to red, green and blue, the
		675	second form applies separate factors to each colour channel, and the last
		676	form includes the alpha channel.
		677
		678	Values from 0 to 1 lower the contrast, values higher than 1 increase the
		679	contrast.
		680
		681	Due to limitations in the underlying XRender extension, lowering contrast
		682	also reduces brightness, while increasing contrast currently also
		683	increases brightness.
		684
		685	=item brightness $bias, $img
		686
		687	=item brightness $r, $g, $b, $img
		688
		689	=item brightness $r, $g, $b, $a, $img
		690
		691	Adjusts the brightness of an image.
		692
		693	The first form applies a single C<$bias> to red, green and blue, the
		694	second form applies separate biases to each colour channel, and the last
		695	form includes the alpha channel.
		696
		697	Values less than 0 reduce brightness, while values larger than 0 increase
		698	it. Useful range is from -1 to 1 - the former results in a black, the
		699	latter in a white picture.
		700
		701	Due to idiosyncrasies in the underlying XRender extension, biases less
		702	than zero can be I<very> slow.
		703
		704	=cut
83		705
84	sub contrast($$;$$;$) {	706	sub contrast($$;$$;$) {
85	my $img = pop;	707	my $img = pop;
86	my ($r, $g, $b, $a) = @_;	708	my ($r, $g, $b, $a) = @_;
87		709
88	($g, $b) = ($r, $r) if @_ < 4;	710	($g, $b) = ($r, $r) if @_ < 3;
89	$a = 1 if @_ < 5;	711	$a = 1 if @_ < 4;
90		712
91	$img = $img->clone;	713	$img = $img->clone;
92	$img->contrast ($r, $g, $b, $a);	714	$img->contrast ($r, $g, $b, $a);
93	$img	715	$img
94	}	716	}
95		717
96	sub brightness($$;$$;$) {	718	sub brightness($$;$$;$) {
97	my $img = pop;	719	my $img = pop;
98	my ($r, $g, $b, $a) = @_;	720	my ($r, $g, $b, $a) = @_;
99		721
100	($g, $b) = ($r, $r) if @_ < 4;	722	($g, $b) = ($r, $r) if @_ < 3;
101	$a = 1 if @_ < 5;	723	$a = 1 if @_ < 4;
102		724
103	$img = $img->clone;	725	$img = $img->clone;
104	$img->brightness ($r, $g, $b, $a);	726	$img->brightness ($r, $g, $b, $a);
105	$img	727	$img
106	}	728	}
107		729
108	sub X() { $new->{position_sensitive} = 1; $l }	730	=item blur $radius, $img
109	sub Y() { $new->{position_sensitive} = 1; $t }
110	sub W() { $new->{size_sensitive} = 1; $w }
111	sub H() { $new->{size_sensitive} = 1; $h }
112		731
113	sub now() { urxvt::NOW }	732	=item blur $radius_horz, $radius_vert, $img
114		733
		734	Gaussian-blurs the image with (roughly) C<$radius> pixel radius. The radii
		735	can also be specified separately.
		736
		737	Blurring is often I<very> slow, at least compared or other
		738	operators. Larger blur radii are slower than smaller ones, too, so if you
		739	don't want to freeze your screen for long times, start experimenting with
		740	low values for radius (<5).
		741
		742	=cut
		743
		744	sub blur($$;$) {
		745	my $img = pop;
		746	$img->blur ($_[0], @_ >= 2 ? $_[1] : $_[0])
		747	}
		748
		749	=back
		750
		751	=head2 OTHER STUFF
		752
		753	Anything that didn't fit any of the other categories, even after appliyng
		754	force and closing our eyes.
		755
		756	=over 4
		757
		758	=item once { ... }
		759
		760	This function takes a code block as argument, that is, one or more
		761	statements enclosed by braces.
		762
		763	The trick is that this code block is only evaluated once - future calls
		764	will simply return the original image (yes, it should only be used with
		765	images).
		766
		767	This can be extremely useful to avoid redoign the same slow operations
		768	again and again- for example, if your background expression takes the root
		769	background, blurs it and then root-aligns it it would have to blur the
		770	root background on every window move or resize.
		771
		772	Putting the blur into a C<once> block will make sure the blur is only done
		773	once:
		774
		775	rootlign once { blur 10, root }
		776
		777	This leaves the question of how to force reevaluation of the block, in
		778	case the root background changes: Right now, all once blocks forget that
		779	they ahve been executed before each time the root background changes (if
		780	the expression is sensitive to that) or when C<once_again> is called.
		781
		782	=item once_again
		783
		784	Resets all C<once> block as if they had never been called, i.e. on the
		785	next call they will be reevaluated again.
		786
		787	=cut
		788
		789	sub once(&) {
		790	$_ONCE_CACHE{$_[0]+0} \|\|= $_[0]()
		791	}
		792
115	sub again($) {	793	sub once_again() {
116	$new->{again} = $_[0];	794	%_ONCE_CACHE = ();
117	}	795	}
118		796
119	sub counter($) {	797	=back
120	$new->{again} = $_[0];	798
121	$bgdsl_self->{counter} + 0	799	=cut
122	}	800
123	}	801	}
124		802
125	sub parse_expr {	803	sub parse_expr {
126	my $expr = eval "sub {\npackage urxvt::bgdsl;\n#line 0 'background expression'\n$_[0]\n}";	804	my $expr = eval "sub {\npackage urxvt::bgdsl;\n#line 0 'background expression'\n$_[0]\n}";
127	die if $@;	805	die if $@;
136	$self->recalculate;	814	$self->recalculate;
137	}	815	}
138		816
139	# evaluate the current bg expression	817	# evaluate the current bg expression
140	sub recalculate {	818	sub recalculate {
141	my ($self) = @_;	819	my ($arg_self) = @_;
142		820
143	# rate limit evaluation	821	# rate limit evaluation
144		822
145	if ($self->{next_refresh} > urxvt::NOW) {	823	if ($arg_self->{next_refresh} > urxvt::NOW) {
146	$self->{next_refresh_timer} = urxvt::timer->new->after ($self->{next_refresh} - urxvt::NOW)->cb (sub {	824	$arg_self->{next_refresh_timer} = urxvt::timer->new->after ($arg_self->{next_refresh} - urxvt::NOW)->cb (sub {
147	$self->recalculate;	825	$arg_self->recalculate;
148	});	826	});
149	return;	827	return;
150	}	828	}
151		829
152	$self->{next_refresh} = urxvt::NOW + $MIN_INTERVAL;	830	$arg_self->{next_refresh} = urxvt::NOW + $MIN_INTERVAL;
153		831
154	# set environment to evaluate user expression	832	# set environment to evaluate user expression
155		833
156	local $bgdsl_self = $self;	834	local $self = $arg_self;
157		835
		836	local $HOME = $ENV{HOME};
158	local $old = $self->{state};	837	local $old = $self->{state};
159	local $new = my $state = $self->{state} = {};	838	local $new = my $state = $self->{state} = {};
160		839
161	($l, $t, $w, $h) =	840	($x, $y, $w, $h) =
162	$self->get_geometry;	841	$self->background_geometry ($self->{border});
163		842
164	# evaluate user expression	843	# evaluate user expression
165		844
166	my $img = eval { $self->{expr}->() };	845	my $img = eval { $self->{expr}->() };
167	warn $@ if $@;#d#	846	warn $@ if $@;#d#
		847	die "background-expr did not return an image.\n" if !UNIVERSAL::isa $img, "urxvt::img";
		848
		849	$state->{size_sensitive} = 1
		850	if $img->repeat_mode != urxvt::RepeatNormal;
168		851
169	# if the expression is sensitive to external events, prepare reevaluation then	852	# if the expression is sensitive to external events, prepare reevaluation then
170		853
171	my $repeat;	854	my $repeat;
172		855
173	if (my $again = $state->{again}) {	856	if (my $again = $state->{again}) {
174	$repeat = 1;	857	$repeat = 1;
		858	my $self = $self;
175	$state->{timer} = $again == $old->{again}	859	$state->{timer} = $again == $old->{again}
176	? $old->{timer}	860	? $old->{timer}
177	: urxvt::timer->new->after ($again)->interval ($again)->cb (sub {	861	: urxvt::timer->new->after ($again)->interval ($again)->cb (sub {
178	++$self->{counter};	862	++$self->{counter};
179	$self->recalculate	863	$self->recalculate
…		…
208	unless ($repeat) {	892	unless ($repeat) {
209	delete $self->{state};	893	delete $self->{state};
210	delete $self->{expr};	894	delete $self->{expr};
211	}	895	}
212		896
213	# prepare and set background pixmap	897	# set background pixmap
214		898
215	$img = $img->sub_rect (0, 0, $w, $h)
216	if $img->w != $w \|\| $img->h != $h;
217
218	$self->set_background ($img);	899	$self->set_background ($img, $self->{border});
219	$self->scr_recolour (0);	900	$self->scr_recolour (0);
220	$self->want_refresh;	901	$self->want_refresh;
221	}	902	}
222		903
223	sub on_start {	904	sub on_start {
224	my ($self) = @_;	905	my ($self) = @_;
225		906
		907	my $expr = $self->x_resource ("%.expr")
		908	or return;
		909
		910	$self->has_render
		911	or die "background extension needs RENDER extension 0.10 or higher, ignoring background-expr.\n";
		912
226	$self->set_expr (parse_expr $EXPR);	913	$self->set_expr (parse_expr $expr);
		914	$self->{border} = $self->x_resource_boolean ("%.border");
		915
		916	$MIN_INTERVAL = $self->x_resource ("%.interval");
227		917
228	()	918	()
229	}	919	}
230		920

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Comparing rxvt-unicode/src/perl/background (file contents): Revision 1.13 by root, Tue Jun 5 19:32:29 2012 UTC vs. Revision 1.52 by root, Tue Jun 12 10:45:53 2012 UTC

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Comparing rxvt-unicode/src/perl/background (file contents):
Revision 1.13 by root, Tue Jun 5 19:32:29 2012 UTC vs.
Revision 1.52 by root, Tue Jun 12 10:45:53 2012 UTC