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

Comparing rxvt-unicode/src/perl/background (file contents):
Revision 1.8 by root, Tue Jun 5 14:07:47 2012 UTC vs.
Revision 1.54 by root, Thu Jun 14 16:22:20 2012 UTC

…		…
1	#! perl	1	#! perl
2		2
3	our $EXPR = 'move load "/root/pix/das_fette_schwein.jpg", repeat_wrap, X, Y';	3	#:META:X_RESOURCE:%.expr:string:background expression
4	$EXPR = '	4	#:META:X_RESOURCE:%.border:boolean:respect the terminal border
5	blur 10, 10,	5	#:META:X_RESOURCE:%.interval:seconds:minimum time between updates
6	rotate W, H, 50, 50, counter 1/60, repeat_mirror,
7	clip X, Y, W, H, repeat_mirror,
8	load "/root/pix/das_fette_schwein.jpg"
9	';
10	#$EXPR = 'blur root, 10, 10'
11	#$EXPR = 'blur move (root, -x, -y), 5, 5'
12	#resize load "/root/pix/das_fette_schwein.jpg", w, h
13		6
14	use Safe;	7	=head1 NAME
15		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 %_ONCE_CACHE;
		209	our $HOME;
16	our ($bgdsl_self, $old, $new);	210	our ($self, $old, $new);
17	our ($l, $t, $w, $h);	211	our ($x, $y, $w, $h);
		212
		213	# enforce at least this interval between updates
		214	our $MIN_INTERVAL = 6/59.951;
18		215
19	{	216	{
20	package urxvt::bgdsl; # background language	217	package urxvt::bgdsl; # background language
21		218
22	*repeat_black = \&urxvt::RepeatNone; #TODO wtf	219	use List::Util qw(min max sum shuffle);
23	*repeat_wrap = \&urxvt::RepeatNormal;	220
24	*repeat_pad = \&urxvt::RepeatPad;	221	=head2 PROVIDERS/GENERATORS
25	*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, and shared between temrinals
		235	running in the same process (e.g. in C<urxvtd>).
		236
		237	=item load_uc $path
		238
		239	Load uncached - same as load, but does not cache the image. This function
		240	is most useufl if you want to optimise a background expression in some
		241	way.
		242
		243	=cut
		244
		245	sub load_uc($) {
		246	my ($path) = @_;
		247
		248	$_IMG_CACHE{$path} \|\| do {
		249	my $img = $self->new_img_from_file ($path);
		250	Scalar::Util::weaken ($_IMG_CACHE{$path} = $img);
		251	$img
		252	}
		253	}
26		254
27	sub load($) {	255	sub load($) {
28	my ($path) = @_;	256	my ($path) = @_;
29		257
30	$new->{load}{$path} = $old->{load}{$path} \|\| $bgdsl_self->new_img_from_file ($path);	258	$new->{load}{$path} = $old->{load}{$path} \|\| load_uc $path;
31	}	259	}
		260
		261	=item root
		262
		263	Returns the root window pixmap, that is, hopefully, the background image
		264	of your screen. The image is set to extend mode.
		265
		266	This function makes your expression root sensitive, that means it will be
		267	reevaluated when the bg image changes.
		268
		269	=cut
32		270
33	sub root() {	271	sub root() {
34	die "root op not supported, exg, we need you";	272	$new->{rootpmap_sensitive} = 1;
		273	$self->new_img_from_root
35	}	274	}
36		275
		276	=item solid $colour
		277
		278	=item solid $width, $height, $colour
		279
		280	Creates a new image and completely fills it with the given colour. The
		281	image is set to tiling mode.
		282
		283	If C<$width> and C<$height> are omitted, it creates a 1x1 image, which is
		284	useful for solid backgrounds or for use in filtering effects.
		285
		286	=cut
		287
		288	sub solid($;$$) {
		289	my $colour = pop;
		290
		291	my $img = $self->new_img (urxvt::PictStandardARGB32, $_[0] \|\| 1, $_[1] \|\| 1);
		292	$img->fill ($colour);
		293	$img
		294	}
		295
		296	=item clone $img
		297
		298	Returns an exact copy of the image. This is useful if you want to have
		299	multiple copies of the same image to apply different effects to.
		300
		301	=cut
		302
37	# sub clone($) {	303	sub clone($) {
38	# $_[0]->clone	304	$_[0]->clone
39	# }	305	}
40		306
		307	=head2 TILING MODES
		308
		309	The following operators modify the tiling mode of an image, that is, the
		310	way that pixels outside the image area are painted when the image is used.
		311
		312	=over 4
		313
		314	=item tile $img
		315
		316	Tiles the whole plane with the image and returns this new image - or in
		317	other words, it returns a copy of the image in plane tiling mode.
		318
		319	Example: load an image and tile it over the background, without
		320	resizing. The C<tile> call is superfluous because C<load> already defaults
		321	to tiling mode.
		322
		323	tile load "mybg.png"
		324
		325	=item mirror $img
		326
		327	Similar to tile, but reflects the image each time it uses a new copy, so
		328	that top edges always touch top edges, right edges always touch right
		329	edges and so on (with normal tiling, left edges always touch right edges
		330	and top always touch bottom edges).
		331
		332	Example: load an image and mirror it over the background, avoiding sharp
		333	edges at the image borders at the expense of mirroring the image itself
		334
		335	mirror load "mybg.png"
		336
		337	=item pad $img
		338
		339	Takes an image and modifies it so that all pixels outside the image area
		340	become transparent. This mode is most useful when you want to place an
		341	image over another image or the background colour while leaving all
		342	background pixels outside the image unchanged.
		343
		344	Example: load an image and display it in the upper left corner. The rest
		345	of the space is left "empty" (transparent or whatever your compositor does
		346	in alpha mode, else background colour).
		347
		348	pad load "mybg.png"
		349
		350	=item extend $img
		351
		352	Extends the image over the whole plane, using the closest pixel in the
		353	area outside the image. This mode is mostly useful when you use more complex
		354	filtering operations and want the pixels outside the image to have the
		355	same values as the pixels near the edge.
		356
		357	Example: just for curiosity, how does this pixel extension stuff work?
		358
		359	extend move 50, 50, load "mybg.png"
		360
		361	=cut
		362
		363	sub pad($) {
		364	my $img = $_[0]->clone;
		365	$img->repeat_mode (urxvt::RepeatNone);
		366	$img
		367	}
		368
		369	sub tile($) {
		370	my $img = $_[0]->clone;
		371	$img->repeat_mode (urxvt::RepeatNormal);
		372	$img
		373	}
		374
		375	sub mirror($) {
		376	my $img = $_[0]->clone;
		377	$img->repeat_mode (urxvt::RepeatReflect);
		378	$img
		379	}
		380
		381	sub extend($) {
		382	my $img = $_[0]->clone;
		383	$img->repeat_mode (urxvt::RepeatPad);
		384	$img
		385	}
		386
		387	=back
		388
		389	=head2 VARIABLE VALUES
		390
		391	The following functions provide variable data such as the terminal window
		392	dimensions. They are not (Perl-) variables, they just return stuff that
		393	varies. Most of them make your expression sensitive to some events, for
		394	example using C<TW> (terminal width) means your expression is evaluated
		395	again when the terminal is resized.
		396
		397	=over 4
		398
		399	=item TX
		400
		401	=item TY
		402
		403	Return the X and Y coordinates of the terminal window (the terminal
		404	window is the full window by default, and the character area only when in
		405	border-respect mode).
		406
		407	Using these functions make your expression sensitive to window moves.
		408
		409	These functions are mainly useful to align images to the root window.
		410
		411	Example: load an image and align it so it looks as if anchored to the
		412	background.
		413
		414	move -TX, -TY, load "mybg.png"
		415
		416	=item TW
		417
		418	Return the width (C<TW>) and height (C<TH>) of the terminal window (the
		419	terminal window is the full window by default, and the character area only
		420	when in border-respect mode).
		421
		422	Using these functions make your expression sensitive to window resizes.
		423
		424	These functions are mainly useful to scale images, or to clip images to
		425	the window size to conserve memory.
		426
		427	Example: take the screen background, clip it to the window size, blur it a
		428	bit, align it to the window position and use it as background.
		429
		430	clip move -TX, -TY, blur 5, root
		431
		432	=cut
		433
		434	sub TX() { $new->{position_sensitive} = 1; $x }
		435	sub TY() { $new->{position_sensitive} = 1; $y }
		436	sub TW() { $new->{size_sensitive} = 1; $w }
		437	sub TH() { $new->{size_sensitive} = 1; $h }
		438
		439	=item now
		440
		441	Returns the current time as (fractional) seconds since the epoch.
		442
		443	Using this expression does I<not> make your expression sensitive to time,
		444	but the next two functions do.
		445
		446	=item again $seconds
		447
		448	When this function is used the expression will be reevaluated again in
		449	C<$seconds> seconds.
		450
		451	Example: load some image and rotate it according to the time of day (as if it were
		452	the hour pointer of a clock). Update this image every minute.
		453
		454	again 60; rotate 50, 50, (now % 86400) * -720 / 86400, scale load "myclock.png"
		455
		456	=item counter $seconds
		457
		458	Like C<again>, but also returns an increasing counter value, starting at
		459	0, which might be useful for some simple animation effects.
		460
		461	=cut
		462
		463	sub now() { urxvt::NOW }
		464
		465	sub again($) {
		466	$new->{again} = $_[0];
		467	}
		468
		469	sub counter($) {
		470	$new->{again} = $_[0];
		471	$self->{counter} + 0
		472	}
		473
		474	=back
		475
		476	=head2 SHAPE CHANGING OPERATORS
		477
		478	The following operators modify the shape, size or position of the image.
		479
		480	=over 4
		481
		482	=item clip $img
		483
		484	=item clip $width, $height, $img
		485
		486	=item clip $x, $y, $width, $height, $img
		487
		488	Clips an image to the given rectangle. If the rectangle is outside the
		489	image area (e.g. when C<$x> or C<$y> are negative) or the rectangle is
		490	larger than the image, then the tiling mode defines how the extra pixels
		491	will be filled.
		492
		493	If C<$x> an C<$y> are missing, then C<0> is assumed for both.
		494
		495	If C<$width> and C<$height> are missing, then the window size will be
		496	assumed.
		497
		498	Example: load an image, blur it, and clip it to the window size to save
		499	memory.
		500
		501	clip blur 10, load "mybg.png"
		502
		503	=cut
		504
41	sub clip($$$$$;$) {	505	sub clip($;$$;$$) {
		506	my $img = pop;
42	my $img = pop;	507	my $h = pop \|\| TH;
		508	my $w = pop \|\| TW;
43	$img->sub_rect ($_[0], $_[1], $_[2], $_[3], $_[4])	509	$img->sub_rect ($_[0], $_[1], $w, $h)
		510	}
		511
		512	=item scale $img
		513
		514	=item scale $size_factor, $img
		515
		516	=item scale $width_factor, $height_factor, $img
		517
		518	Scales the image by the given factors in horizontal
		519	(C<$width>) and vertical (C<$height>) direction.
		520
		521	If only one factor is give, it is used for both directions.
		522
		523	If no factors are given, scales the image to the window size without
		524	keeping aspect.
		525
		526	=item resize $width, $height, $img
		527
		528	Resizes the image to exactly C<$width> times C<$height> pixels.
		529
		530	=item fit $img
		531
		532	=item fit $width, $height, $img
		533
		534	Fits the image into the given C<$width> and C<$height> without changing
		535	aspect, or the terminal size. That means it will be shrunk or grown until
		536	the whole image fits into the given area, possibly leaving borders.
		537
		538	=item cover $img
		539
		540	=item cover $width, $height, $img
		541
		542	Similar to C<fit>, but shrinks or grows until all of the area is covered
		543	by the image, so instead of potentially leaving borders, it will cut off
		544	image data that doesn't fit.
		545
		546	=cut
		547
		548	sub scale($;$;$) {
		549	my $img = pop;
		550
		551	@_ == 2 ? $img->scale ($_[0] * $img->w, $_[1] * $img->h)
		552	: @_ ? $img->scale ($_[0] * $img->w, $_[0] * $img->h)
		553	: $img->scale (TW, TH)
44	}	554	}
45		555
46	sub resize($$$) {	556	sub resize($$$) {
47	my $img = pop;	557	my $img = pop;
48	$img->scale ($_[0], $_[1])	558	$img->scale ($_[0], $_[1])
49	}	559	}
50		560
51	# TODO: ugly	561	sub fit($;$$) {
		562	my $img = pop;
		563	my $w = ($_[0] \|\| TW) / $img->w;
		564	my $h = ($_[1] \|\| TH) / $img->h;
		565	scale +(min $w, $h), $img
		566	}
		567
		568	sub cover($;$$) {
		569	my $img = pop;
		570	my $w = ($_[0] \|\| TW) / $img->w;
		571	my $h = ($_[1] \|\| TH) / $img->h;
		572	scale +(max $w, $h), $img
		573	}
		574
		575	=item move $dx, $dy, $img
		576
		577	Moves the image by C<$dx> pixels in the horizontal, and C<$dy> pixels in
		578	the vertical.
		579
		580	Example: move the image right by 20 pixels and down by 30.
		581
		582	move 20, 30, ...
		583
		584	=item align $xalign, $yalign, $img
		585
		586	Aligns the image according to a factor - C<0> means the image is moved to
		587	the left or top edge (for C<$xalign> or C<$yalign>), C<0.5> means it is
		588	exactly centered and C<1> means it touches the right or bottom edge.
		589
		590	Example: remove any visible border around an image, center it vertically but move
		591	it to the right hand side.
		592
		593	align 1, 0.5, pad $img
		594
		595	=item center $img
		596
		597	=item center $width, $height, $img
		598
		599	Centers the image, i.e. the center of the image is moved to the center of
		600	the terminal window (or the box specified by C<$width> and C<$height> if
		601	given).
		602
		603	Example: load an image and center it.
		604
		605	center pad load "mybg.png"
		606
		607	=item rootalign $img
		608
		609	Moves the image so that it appears glued to the screen as opposed to the
		610	window. This gives the illusion of a larger area behind the window. It is
		611	exactly equivalent to C<move -TX, -TY>, that is, it moves the image to the
		612	top left of the screen.
		613
		614	Example: load a background image, put it in mirror mode and root align it.
		615
		616	rootalign mirror load "mybg.png"
		617
		618	Example: take the screen background and align it, giving the illusion of
		619	transparency as long as the window isn't in front of other windows.
		620
		621	rootalign root
		622
		623	=cut
		624
52	sub move($$;$) {	625	sub move($$;$) {
53	my $img = pop;	626	my $img = pop->clone;
		627	$img->move ($_[0], $_[1]);
		628	$img
		629	}
		630
		631	sub align($;$$) {
		632	my $img = pop;
		633
		634	move $_[0] * (TW - $img->w),
		635	$_[1] * (TH - $img->h),
		636	$img
		637	}
		638
		639	sub center($;$$) {
		640	my $img = pop;
		641	my $w = $_[0] \|\| TW;
		642	my $h = $_[1] \|\| TH;
		643
		644	move 0.5 * ($w - $img->w), 0.5 * ($h - $img->h), $img
		645	}
		646
		647	sub rootalign($) {
		648	move -TX, -TY, $_[0]
		649	}
		650
		651	=item rotate $center_x, $center_y, $degrees
		652
		653	Rotates the image by C<$degrees> degrees, counter-clockwise, around the
		654	pointer at C<$center_x> and C<$center_y> (specified as factor of image
		655	width/height).
		656
		657	#TODO# new width, height, maybe more operators?
		658
		659	Example: rotate the image by 90 degrees
		660
		661	=cut
		662
		663	sub rotate($$$$) {
		664	my $img = pop;
54	$img->sub_rect (	665	$img->rotate (
55	$_[0], $_[1],	666	$_[0] * $img->w,
56	$img->w, $img->h,	667	$_[1] * $img->h,
57	$_[2],	668	$_[2] * (3.14159265 / 180),
58	)	669	)
59	}	670	}
60		671
61	sub rotate($$$$$$;$) {	672	=back
62	my $img = pop;
63	$img->rotate (
64	$_[0],
65	$_[1],
66	$_[2] * $img->w * .01,
67	$_[3] * $img->h * .01,
68	$_[4] * (3.14159265 / 180),
69	$_[5],
70	)
71	}
72		673
73	sub blur($$$) {	674	=head2 COLOUR MODIFICATIONS
74	my ($rh, $rv, $img) = @_;
75		675
76	$img = $img->clone;	676	The following operators change the pixels of the image.
77	$img->blur ($rh, $rv);	677
78	$img	678	=over 4
79	}	679
		680	=item contrast $factor, $img
		681
		682	=item contrast $r, $g, $b, $img
		683
		684	=item contrast $r, $g, $b, $a, $img
		685
		686	Adjusts the I<contrast> of an image.
		687
		688	The first form applies a single C<$factor> to red, green and blue, the
		689	second form applies separate factors to each colour channel, and the last
		690	form includes the alpha channel.
		691
		692	Values from 0 to 1 lower the contrast, values higher than 1 increase the
		693	contrast.
		694
		695	Due to limitations in the underlying XRender extension, lowering contrast
		696	also reduces brightness, while increasing contrast currently also
		697	increases brightness.
		698
		699	=item brightness $bias, $img
		700
		701	=item brightness $r, $g, $b, $img
		702
		703	=item brightness $r, $g, $b, $a, $img
		704
		705	Adjusts the brightness of an image.
		706
		707	The first form applies a single C<$bias> to red, green and blue, the
		708	second form applies separate biases to each colour channel, and the last
		709	form includes the alpha channel.
		710
		711	Values less than 0 reduce brightness, while values larger than 0 increase
		712	it. Useful range is from -1 to 1 - the former results in a black, the
		713	latter in a white picture.
		714
		715	Due to idiosyncrasies in the underlying XRender extension, biases less
		716	than zero can be I<very> slow.
		717
		718	=cut
80		719
81	sub contrast($$;$$;$) {	720	sub contrast($$;$$;$) {
82	my $img = pop;	721	my $img = pop;
83	my ($r, $g, $b, $a) = @_;	722	my ($r, $g, $b, $a) = @_;
84		723
85	($g, $b) = ($r, $r) if @_ < 4;	724	($g, $b) = ($r, $r) if @_ < 3;
86	$a = 1 if @_ < 5;	725	$a = 1 if @_ < 4;
87		726
88	$img = $img->clone;	727	$img = $img->clone;
89	$img->contrast ($r, $g, $b, $a);	728	$img->contrast ($r, $g, $b, $a);
90	$img	729	$img
91	}	730	}
92		731
93	sub brightness($$;$$;$) {	732	sub brightness($$;$$;$) {
94	my $img = pop;	733	my $img = pop;
95	my ($r, $g, $b, $a) = @_;	734	my ($r, $g, $b, $a) = @_;
96		735
97	($g, $b) = ($r, $r) if @_ < 4;	736	($g, $b) = ($r, $r) if @_ < 3;
98	$a = 1 if @_ < 5;	737	$a = 1 if @_ < 4;
99		738
100	$img = $img->clone;	739	$img = $img->clone;
101	$img->brightness ($r, $g, $b, $a);	740	$img->brightness ($r, $g, $b, $a);
102	$img	741	$img
103	}	742	}
104		743
105	sub X() { $new->{position_sensitive} = 1; $l }	744	=item blur $radius, $img
106	sub Y() { $new->{position_sensitive} = 1; $t }
107	sub W() { $new->{size_sensitive} = 1; $w }
108	sub H() { $new->{size_sensitive} = 1; $h }
109		745
110	sub now() { urxvt::NOW }	746	=item blur $radius_horz, $radius_vert, $img
111		747
		748	Gaussian-blurs the image with (roughly) C<$radius> pixel radius. The radii
		749	can also be specified separately.
		750
		751	Blurring is often I<very> slow, at least compared or other
		752	operators. Larger blur radii are slower than smaller ones, too, so if you
		753	don't want to freeze your screen for long times, start experimenting with
		754	low values for radius (<5).
		755
		756	=cut
		757
		758	sub blur($$;$) {
		759	my $img = pop;
		760	$img->blur ($_[0], @_ >= 2 ? $_[1] : $_[0])
		761	}
		762
		763	=back
		764
		765	=head2 OTHER STUFF
		766
		767	Anything that didn't fit any of the other categories, even after appliyng
		768	force and closing our eyes.
		769
		770	=over 4
		771
		772	=item once { ... }
		773
		774	This function takes a code block as argument, that is, one or more
		775	statements enclosed by braces.
		776
		777	The trick is that this code block is only evaluated once - future calls
		778	will simply return the original image (yes, it should only be used with
		779	images).
		780
		781	This can be extremely useful to avoid redoign the same slow operations
		782	again and again- for example, if your background expression takes the root
		783	background, blurs it and then root-aligns it it would have to blur the
		784	root background on every window move or resize.
		785
		786	Putting the blur into a C<once> block will make sure the blur is only done
		787	once:
		788
		789	rootlign once { blur 10, root }
		790
		791	This leaves the question of how to force reevaluation of the block, in
		792	case the root background changes: Right now, all once blocks forget that
		793	they ahve been executed before each time the root background changes (if
		794	the expression is sensitive to that) or when C<once_again> is called.
		795
		796	=item once_again
		797
		798	Resets all C<once> block as if they had never been called, i.e. on the
		799	next call they will be reevaluated again.
		800
		801	=cut
		802
		803	sub once(&) {
		804	$_ONCE_CACHE{$_[0]+0} \|\|= $_[0]()
		805	}
		806
112	sub again($) {	807	sub once_again() {
113	$new->{again} = $_[0];	808	%_ONCE_CACHE = ();
114	}	809	}
115		810
116	sub counter($) {	811	=back
117	$new->{again} = $_[0];	812
118	$bgdsl_self->{counter} + 0	813	=cut
119	}	814
120	}	815	}
121		816
122	sub parse_expr {	817	sub parse_expr {
123	my $expr = eval "sub {\npackage urxvt::bgdsl;\n#line 0 'background expression'\n$_[0]\n}";	818	my $expr = eval "sub {\npackage urxvt::bgdsl;\n#line 0 'background expression'\n$_[0]\n}";
124	die if $@;	819	die if $@;
133	$self->recalculate;	828	$self->recalculate;
134	}	829	}
135		830
136	# evaluate the current bg expression	831	# evaluate the current bg expression
137	sub recalculate {	832	sub recalculate {
138	my ($self) = @_;	833	my ($arg_self) = @_;
139		834
140	#TODO: rate limit calls	835	# rate limit evaluation
141		836
142	local $bgdsl_self = $self;	837	if ($arg_self->{next_refresh} > urxvt::NOW) {
		838	$arg_self->{next_refresh_timer} = urxvt::timer->new->after ($arg_self->{next_refresh} - urxvt::NOW)->cb (sub {
		839	$arg_self->recalculate;
		840	});
		841	return;
		842	}
143		843
		844	$arg_self->{next_refresh} = urxvt::NOW + $MIN_INTERVAL;
		845
		846	# set environment to evaluate user expression
		847
		848	local $self = $arg_self;
		849
		850	local $HOME = $ENV{HOME};
144	local $old = $self->{state};	851	local $old = $self->{state};
145	local $new = my $state = $self->{state} = {};	852	local $new = my $state = $self->{state} = {};
146		853
147	($l, $t, $w, $h) =	854	($x, $y, $w, $h) =
148	$self->get_geometry;	855	$self->background_geometry ($self->{border});
		856
		857	# evaluate user expression
149		858
150	my $img = eval { $self->{expr}->() };	859	my $img = eval { $self->{expr}->() };
151	warn $@ if $@;#d#	860	warn $@ if $@;#d#
		861	die "background-expr did not return an image.\n" if !UNIVERSAL::isa $img, "urxvt::img";
		862
		863	$state->{size_sensitive} = 1
		864	if $img->repeat_mode != urxvt::RepeatNormal;
		865
		866	# if the expression is sensitive to external events, prepare reevaluation then
152		867
153	my $repeat;	868	my $repeat;
154		869
155	if (my $again = $state->{again}) {	870	if (my $again = $state->{again}) {
156	$repeat = 1;	871	$repeat = 1;
		872	my $self = $self;
157	$state->{timer} = $again == $old->{again}	873	$state->{timer} = $again == $old->{again}
158	? $old->{timer}	874	? $old->{timer}
159	: urxvt::timer->new->after ($again)->interval ($again)->cb (sub {	875	: urxvt::timer->new->after ($again)->interval ($again)->cb (sub {
160	++$self->{counter};	876	++$self->{counter};
161	$self->recalculate	877	$self->recalculate
…		…
174	$self->enable (size_change => sub { $_[0]->recalculate });	890	$self->enable (size_change => sub { $_[0]->recalculate });
175	} else {	891	} else {
176	$self->disable ("size_change");	892	$self->disable ("size_change");
177	}	893	}
178		894
		895	if (delete $state->{rootpmap_sensitive}) {
		896	$repeat = 1;
		897	$self->enable (rootpmap_change => sub { $_[0]->recalculate });
		898	} else {
		899	$self->disable ("rootpmap_change");
		900	}
		901
		902	# clear stuff we no longer need
		903
179	%$old = ();	904	%$old = ();
180		905
181	unless ($repeat) {	906	unless ($repeat) {
182	delete $self->{state};	907	delete $self->{state};
183	delete $self->{expr};	908	delete $self->{expr};
184	}	909	}
185		910
186	$img = $img->sub_rect (0, 0, $w, $h)	911	# set background pixmap
187	if $img->w != $w \|\| $img->h != $h;
188		912
189	$self->set_background ($img);	913	$self->set_background ($img, $self->{border});
190	$self->scr_recolour (0);	914	$self->scr_recolour (0);
191	$self->want_refresh;	915	$self->want_refresh;
192	}	916	}
193		917
194	sub on_start {	918	sub on_start {
195	my ($self) = @_;	919	my ($self) = @_;
196		920
		921	my $expr = $self->x_resource ("%.expr")
		922	or return;
		923
		924	$self->has_render
		925	or die "background extension needs RENDER extension 0.10 or higher, ignoring background-expr.\n";
		926
197	$self->set_expr (parse_expr $EXPR);	927	$self->set_expr (parse_expr $expr);
		928	$self->{border} = $self->x_resource_boolean ("%.border");
		929
		930	$MIN_INTERVAL = $self->x_resource ("%.interval");
198		931
199	()	932	()
200	}	933	}
201		934

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Comparing rxvt-unicode/src/perl/background (file contents): Revision 1.8 by root, Tue Jun 5 14:07:47 2012 UTC vs. Revision 1.54 by root, Thu Jun 14 16:22:20 2012 UTC

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Comparing rxvt-unicode/src/perl/background (file contents):
Revision 1.8 by root, Tue Jun 5 14:07:47 2012 UTC vs.
Revision 1.54 by root, Thu Jun 14 16:22:20 2012 UTC