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

Comparing rxvt-unicode/src/perl/background (file contents):
Revision 1.1 by root, Mon Jun 4 21:39:56 2012 UTC vs.
Revision 1.82 by sf-exg, Sat Jan 19 10:04:34 2013 UTC

1	#! perl	1	#! perl
2		2
3	our $EXPR = 'resize (blur (load "/root/pix/das_fette_schwein.jpg", 1 + (counter 1) % 10, 10), w, h)';	3	#:META:X_RESOURCE:%.expr:string:background expression
4	#$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
		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 QUICK AND DIRTY CHEAT SHEET
		18
		19	Just load a random jpeg image and tile the background with it without
		20	scaling or anything else:
		21
		22	load "/path/to/img.jpg"
		23
		24	The same, but use mirroring/reflection instead of tiling:
		25
		26	mirror load "/path/to/img.jpg"
		27
		28	Load an image and scale it to exactly fill the terminal window:
		29
		30	scale keep { load "/path/to/img.jpg" }
		31
		32	Implement pseudo-transparency by using a suitably-aligned root pixmap
		33	as window background:
		34
		35	rootalign root
		36
		37	Likewise, but keep a blurred copy:
		38
		39	rootalign keep { blur 10, root }
		40
		41	=head1 DESCRIPTION
		42
		43	This extension manages the terminal background by creating a picture that
		44	is behind the text, replacing the normal background colour.
		45
		46	It does so by evaluating a Perl expression that I<calculates> the image on
		47	the fly, for example, by grabbing the root background or loading a file.
		48
		49	While the full power of Perl is available, the operators have been design
		50	to be as simple as possible.
		51
		52	For example, to load an image and scale it to the window size, you would
		53	use:
		54
		55	urxvt --background-expr 'scale keep { load "/path/to/mybg.png" }'
		56
		57	Or specified as a X resource:
		58
		59	URxvt.background-expr: scale keep { load "/path/to/mybg.png" }
		60
		61	=head1 THEORY OF OPERATION
		62
		63	At startup, just before the window is mapped for the first time, the
		64	expression is evaluated and must yield an image. The image is then
		65	extended as necessary to cover the whole terminal window, and is set as a
		66	background pixmap.
		67
		68	If the image contains an alpha channel, then it will be used as-is in
		69	visuals that support alpha channels (for example, for a compositing
		70	manager). In other visuals, the terminal background colour will be used to
		71	replace any transparency.
		72
		73	When the expression relies, directly or indirectly, on the window size,
		74	position, the root pixmap, or a timer, then it will be remembered. If not,
		75	then it will be removed.
		76
		77	If any of the parameters that the expression relies on changes (when the
		78	window is moved or resized, its position or size changes; when the root
		79	pixmap is replaced by another one the root background changes; or when the
		80	timer elapses), then the expression will be evaluated again.
		81
		82	For example, an expression such as C<scale keep { load "$HOME/mybg.png"
		83	}> scales the image to the window size, so it relies on the window size
		84	and will be reevaluated each time it is changed, but not when it moves for
		85	example. That ensures that the picture always fills the terminal, even
		86	after its size changes.
		87
		88	=head2 EXPRESSIONS
		89
		90	Expressions are normal Perl expressions, in fact, they are Perl blocks -
		91	which means you could use multiple lines and statements:
		92
		93	scale keep {
		94	again 3600;
		95	if (localtime now)[6]) {
		96	return load "$HOME/weekday.png";
		97	} else {
		98	return load "$HOME/sunday.png";
		99	}
		100	}
		101
		102	This inner expression is evaluated once per hour (and whenever the
		103	terminal window is resized). It sets F<sunday.png> as background on
		104	Sundays, and F<weekday.png> on all other days.
		105
		106	Fortunately, we expect that most expressions will be much simpler, with
		107	little Perl knowledge needed.
		108
		109	Basically, you always start with a function that "generates" an image
		110	object, such as C<load>, which loads an image from disk, or C<root>, which
		111	returns the root window background image:
		112
		113	load "$HOME/mypic.png"
		114
		115	The path is usually specified as a quoted string (the exact rules can be
		116	found in the L<perlop> manpage). The F<$HOME> at the beginning of the
		117	string is expanded to the home directory.
		118
		119	Then you prepend one or more modifiers or filtering expressions, such as
		120	C<scale>:
		121
		122	scale load "$HOME/mypic.png"
		123
		124	Just like a mathematical expression with functions, you should read these
		125	expressions from right to left, as the C<load> is evaluated first, and
		126	its result becomes the argument to the C<scale> function.
		127
		128	Many operators also allow some parameters preceding the input image
		129	that modify its behaviour. For example, C<scale> without any additional
		130	arguments scales the image to size of the terminal window. If you specify
		131	an additional argument, it uses it as a scale factor (multiply by 100 to
		132	get a percentage):
		133
		134	scale 2, load "$HOME/mypic.png"
		135
		136	This enlarges the image by a factor of 2 (200%). As you can see, C<scale>
		137	has now two arguments, the C<200> and the C<load> expression, while
		138	C<load> only has one argument. Arguments are separated from each other by
		139	commas.
		140
		141	Scale also accepts two arguments, which are then separate factors for both
		142	horizontal and vertical dimensions. For example, this halves the image
		143	width and doubles the image height:
		144
		145	scale 0.5, 2, load "$HOME/mypic.png"
		146
		147	IF you try out these expressions, you might suffer from some sluggishness,
		148	because each time the terminal is resized, it loads the PNG image again
		149	and scales it. Scaling is usually fast (and unavoidable), but loading the
		150	image can be quite time consuming. This is where C<keep> comes in handy:
		151
		152	scale 0.5, 2, keep { load "$HOME/mypic.png" }
		153
		154	The C<keep> operator executes all the statements inside the braces only
		155	once, or when it thinks the outcome might change. In other cases it
		156	returns the last value computed by the brace block.
		157
		158	This means that the C<load> is only executed once, which makes it much
		159	faster, but also means that more memory is being used, because the loaded
		160	image must be kept in memory at all times. In this expression, the
		161	trade-off is likely worth it.
		162
		163	But back to effects: Other effects than scaling are also readily
		164	available, for example, you can tile the image to fill the whole window,
		165	instead of resizing it:
		166
		167	tile keep { load "$HOME/mypic.png" }
		168
		169	In fact, images returned by C<load> are in C<tile> mode by default, so the
		170	C<tile> operator is kind of superfluous.
		171
		172	Another common effect is to mirror the image, so that the same edges
		173	touch:
		174
		175	mirror keep { load "$HOME/mypic.png" }
		176
		177	Another common background expression is:
		178
		179	rootalign root
		180
		181	This one first takes a snapshot of the screen background image, and then
		182	moves it to the upper left corner of the screen (as opposed to the upper
		183	left corner of the terminal window)- the result is pseudo-transparency:
		184	the image seems to be static while the window is moved around.
		185
		186	=head2 COLOUR SPECIFICATIONS
		187
		188	Whenever an operator expects a "colour", then this can be specified in one
		189	of two ways: Either as string with an X11 colour specification, such as:
		190
		191	"red" # named colour
		192	"#f00" # simple rgb
		193	"[50]red" # red with 50% alpha
		194	"TekHVC:300/50/50" # anything goes
		195
		196	OR as an array reference with one, three or four components:
		197
		198	[0.5] # 50% gray, 100% alpha
		199	[0.5, 0, 0] # dark red, no green or blur, 100% alpha
		200	[0.5, 0, 0, 0.7] # same with explicit 70% alpha
		201
		202	=head2 CACHING AND SENSITIVITY
		203
		204	Since some operations (such as C<load> and C<blur>) can take a long time,
		205	caching results can be very important for a smooth operation. Caching can
		206	also be useful to reduce memory usage, though, for example, when an image
		207	is cached by C<load>, it could be shared by multiple terminal windows
		208	running inside urxvtd.
		209
		210	=head3 C<keep { ... }> caching
		211
		212	The most important way to cache expensive operations is to use C<keep {
		213	... }>. The C<keep> operator takes a block of multiple statements enclosed
		214	by C<{}> and keeps the return value in memory.
		215
		216	An expression can be "sensitive" to various external events, such as
		217	scaling or moving the window, root background changes and timers. Simply
		218	using an expression (such as C<scale> without parameters) that depends on
		219	certain changing values (called "variables"), or using those variables
		220	directly, will make an expression sensitive to these events - for example,
		221	using C<scale> or C<TW> will make the expression sensitive to the terminal
		222	size, and thus to resizing events.
		223
		224	When such an event happens, C<keep> will automatically trigger a
		225	reevaluation of the whole expression with the new value of the expression.
		226
		227	C<keep> is most useful for expensive operations, such as C<blur>:
		228
		229	rootalign keep { blur 20, root }
		230
		231	This makes a blurred copy of the root background once, and on subsequent
		232	calls, just root-aligns it. Since C<blur> is usually quite slow and
		233	C<rootalign> is quite fast, this trades extra memory (for the cached
		234	blurred pixmap) with speed (blur only needs to be redone when root
		235	changes).
		236
		237	=head3 C<load> caching
		238
		239	The C<load> operator itself does not keep images in memory, but as long as
		240	the image is still in memory, C<load> will use the in-memory image instead
		241	of loading it freshly from disk.
		242
		243	That means that this expression:
		244
		245	keep { load "$HOME/path..." }
		246
		247	Not only caches the image in memory, other terminal instances that try to
		248	C<load> it can reuse that in-memory copy.
		249
		250	=head1 REFERENCE
		251
		252	=head2 COMMAND LINE SWITCHES
		253
		254	=over 4
		255
		256	=item --background-expr perl-expression
		257
		258	Specifies the Perl expression to evaluate.
		259
		260	=item --background-border
		261
		262	By default, the expression creates an image that fills the full window,
		263	overwriting borders and any other areas, such as the scrollbar.
		264
		265	Specifying this flag changes the behaviour, so that the image only
		266	replaces the background of the character area.
		267
		268	=item --background-interval seconds
		269
		270	Since some operations in the underlying XRender extension can effectively
		271	freeze your X-server for prolonged time, this extension enforces a minimum
		272	time between updates, which is normally about 0.1 seconds.
		273
		274	If you want to do updates more often, you can decrease this safety
		275	interval with this switch.
		276
		277	=back
		278
		279	=cut
		280
		281	our %_IMG_CACHE;
		282	our $HOME;
		283	our ($self, $frame);
		284	our ($x, $y, $w, $h);
		285
		286	# enforce at least this interval between updates
		287	our $MIN_INTERVAL = 6/59.951;
9		288
10	{	289	{
11	package urxvt::bgdsl::vars;
12
13	our ($self, $old, $new);
14	our ($x, $y, $w, $h);
15
16	package urxvt::bgdsl; # background language	290	package urxvt::bgdsl; # background language
17		291
18	*repeat_black = \&urxvt::RepeatNone; #TODO wtf	292	sub FR_PARENT() { 0 } # parent frame, if any - must be #0
19	*repeat_wrap = \&urxvt::RepeatNormal;	293	sub FR_CACHE () { 1 } # cached values
20	*repeat_pad = \&urxvt::RepeatPad;	294	sub FR_AGAIN () { 2 } # what this expr is sensitive to
21	*repeat_mirror = \&urxvt::RepeatReflect;	295	sub FR_STATE () { 3 } # watchers etc.
22		296
		297	use List::Util qw(min max sum shuffle);
		298
		299	=head2 PROVIDERS/GENERATORS
		300
		301	These functions provide an image, by loading it from disk, grabbing it
		302	from the root screen or by simply generating it. They are used as starting
		303	points to get an image you can play with.
		304
		305	=over 4
		306
		307	=item load $path
		308
		309	Loads the image at the given C<$path>. The image is set to plane tiling
		310	mode.
		311
		312	If the image is already in memory (e.g. because another terminal instance
		313	uses it), then the in-memory copy us returned instead.
		314
		315	=item load_uc $path
		316
		317	Load uncached - same as load, but does not cache the image, which means it
		318	is I<always> loaded from the filesystem again, even if another copy of it
		319	is in memory at the time.
		320
		321	=cut
		322
		323	sub load_uc($) {
		324	$self->new_img_from_file ($_[0])
		325	}
		326
23	sub load {	327	sub load($) {
24	my ($path) = @_;	328	my ($path) = @_;
25		329
26	$new->{load}{$path} = $old->{load}{$path} \|\| $self->new_img_from_file ($path);	330	$_IMG_CACHE{$path} \|\| do {
		331	my $img = load_uc $path;
		332	Scalar::Util::weaken ($_IMG_CACHE{$path} = $img);
		333	$img
		334	}
27	}	335	}
28		336
		337	=item root
		338
		339	Returns the root window pixmap, that is, hopefully, the background image
		340	of your screen.
		341
		342	This function makes your expression root sensitive, that means it will be
		343	reevaluated when the bg image changes.
		344
		345	=cut
		346
29	sub root {	347	sub root() {
30	die "root op not supported, exg, we need you";	348	$frame->[FR_AGAIN]{rootpmap} = 1;
		349	$self->new_img_from_root
31	}	350	}
32		351
		352	=item solid $colour
		353
		354	=item solid $width, $height, $colour
		355
		356	Creates a new image and completely fills it with the given colour. The
		357	image is set to tiling mode.
		358
		359	If C<$width> and C<$height> are omitted, it creates a 1x1 image, which is
		360	useful for solid backgrounds or for use in filtering effects.
		361
		362	=cut
		363
		364	sub solid($;$$) {
		365	my $colour = pop;
		366
		367	my $img = $self->new_img (urxvt::PictStandardARGB32, 0, 0, $_[0] \|\| 1, $_[1] \|\| 1);
		368	$img->fill ($colour);
		369	$img
		370	}
		371
		372	=item clone $img
		373
		374	Returns an exact copy of the image. This is useful if you want to have
		375	multiple copies of the same image to apply different effects to.
		376
		377	=cut
		378
		379	sub clone($) {
		380	$_[0]->clone
		381	}
		382
		383	=item merge $img ...
		384
		385	Takes any number of images and merges them together, creating a single
		386	image containing them all. The tiling mode of the first image is used as
		387	the tiling mode of the resulting image.
		388
		389	This function is called automatically when an expression returns multiple
		390	images.
		391
		392	=cut
		393
		394	sub merge(@) {
		395	return $_[0] unless $#_;
		396
		397	# rather annoyingly clumsy, but optimisation is for another time
		398
		399	my $x0 = +1e9;
		400	my $y0 = +1e9;
		401	my $x1 = -1e9;
		402	my $y1 = -1e9;
		403
		404	for (@_) {
		405	my ($x, $y, $w, $h) = $_->geometry;
		406
		407	$x0 = $x if $x0 > $x;
		408	$y0 = $y if $y0 > $y;
		409
		410	$x += $w;
		411	$y += $h;
		412
		413	$x1 = $x if $x1 < $x;
		414	$y1 = $y if $y1 < $y;
		415	}
		416
		417	my $base = $self->new_img (urxvt::PictStandardARGB32, $x0, $y0, $x1 - $x0, $y1 - $y0);
		418	$base->repeat_mode ($_[0]->repeat_mode);
		419	$base->fill ([0, 0, 0, 0]);
		420
		421	$base->draw ($_)
		422	for @_;
		423
		424	$base
		425	}
		426
		427	=back
		428
		429	=head2 TILING MODES
		430
		431	The following operators modify the tiling mode of an image, that is, the
		432	way that pixels outside the image area are painted when the image is used.
		433
		434	=over 4
		435
		436	=item tile $img
		437
		438	Tiles the whole plane with the image and returns this new image - or in
		439	other words, it returns a copy of the image in plane tiling mode.
		440
		441	Example: load an image and tile it over the background, without
		442	resizing. The C<tile> call is superfluous because C<load> already defaults
		443	to tiling mode.
		444
		445	tile load "mybg.png"
		446
		447	=item mirror $img
		448
		449	Similar to tile, but reflects the image each time it uses a new copy, so
		450	that top edges always touch top edges, right edges always touch right
		451	edges and so on (with normal tiling, left edges always touch right edges
		452	and top always touch bottom edges).
		453
		454	Example: load an image and mirror it over the background, avoiding sharp
		455	edges at the image borders at the expense of mirroring the image itself
		456
		457	mirror load "mybg.png"
		458
		459	=item pad $img
		460
		461	Takes an image and modifies it so that all pixels outside the image area
		462	become transparent. This mode is most useful when you want to place an
		463	image over another image or the background colour while leaving all
		464	background pixels outside the image unchanged.
		465
		466	Example: load an image and display it in the upper left corner. The rest
		467	of the space is left "empty" (transparent or whatever your compositor does
		468	in alpha mode, else background colour).
		469
		470	pad load "mybg.png"
		471
		472	=item extend $img
		473
		474	Extends the image over the whole plane, using the closest pixel in the
		475	area outside the image. This mode is mostly useful when you use more complex
		476	filtering operations and want the pixels outside the image to have the
		477	same values as the pixels near the edge.
		478
		479	Example: just for curiosity, how does this pixel extension stuff work?
		480
		481	extend move 50, 50, load "mybg.png"
		482
		483	=cut
		484
		485	sub pad($) {
		486	my $img = $_[0]->clone;
		487	$img->repeat_mode (urxvt::RepeatNone);
		488	$img
		489	}
		490
		491	sub tile($) {
		492	my $img = $_[0]->clone;
		493	$img->repeat_mode (urxvt::RepeatNormal);
		494	$img
		495	}
		496
		497	sub mirror($) {
		498	my $img = $_[0]->clone;
		499	$img->repeat_mode (urxvt::RepeatReflect);
		500	$img
		501	}
		502
		503	sub extend($) {
		504	my $img = $_[0]->clone;
		505	$img->repeat_mode (urxvt::RepeatPad);
		506	$img
		507	}
		508
		509	=back
		510
		511	=head2 VARIABLE VALUES
		512
		513	The following functions provide variable data such as the terminal window
		514	dimensions. They are not (Perl-) variables, they just return stuff that
		515	varies. Most of them make your expression sensitive to some events, for
		516	example using C<TW> (terminal width) means your expression is evaluated
		517	again when the terminal is resized.
		518
		519	=over 4
		520
		521	=item TX
		522
		523	=item TY
		524
		525	Return the X and Y coordinates of the terminal window (the terminal
		526	window is the full window by default, and the character area only when in
		527	border-respect mode).
		528
		529	Using these functions make your expression sensitive to window moves.
		530
		531	These functions are mainly useful to align images to the root window.
		532
		533	Example: load an image and align it so it looks as if anchored to the
		534	background (that's exactly what C<rootalign> does btw.):
		535
		536	move -TX, -TY, keep { load "mybg.png" }
		537
		538	=item TW
		539
		540	=item TH
		541
		542	Return the width (C<TW>) and height (C<TH>) of the terminal window (the
		543	terminal window is the full window by default, and the character area only
		544	when in border-respect mode).
		545
		546	Using these functions make your expression sensitive to window resizes.
		547
		548	These functions are mainly useful to scale images, or to clip images to
		549	the window size to conserve memory.
		550
		551	Example: take the screen background, clip it to the window size, blur it a
		552	bit, align it to the window position and use it as background.
		553
		554	clip move -TX, -TY, keep { blur 5, root }
		555
		556	=cut
		557
		558	sub TX() { $frame->[FR_AGAIN]{position} = 1; $x }
		559	sub TY() { $frame->[FR_AGAIN]{position} = 1; $y }
		560	sub TW() { $frame->[FR_AGAIN]{size} = 1; $w }
		561	sub TH() { $frame->[FR_AGAIN]{size} = 1; $h }
		562
		563	=item now
		564
		565	Returns the current time as (fractional) seconds since the epoch.
		566
		567	Using this expression does I<not> make your expression sensitive to time,
		568	but the next two functions do.
		569
		570	=item again $seconds
		571
		572	When this function is used the expression will be reevaluated again in
		573	C<$seconds> seconds.
		574
		575	Example: load some image and rotate it according to the time of day (as if it were
		576	the hour pointer of a clock). Update this image every minute.
		577
		578	again 60;
		579	rotate 50, 50, (now % 86400) * -72 / 8640, scale keep { load "myclock.png" }
		580
		581	=item counter $seconds
		582
		583	Like C<again>, but also returns an increasing counter value, starting at
		584	0, which might be useful for some simple animation effects.
		585
		586	=cut
		587
		588	sub now() { urxvt::NOW }
		589
		590	sub again($) {
		591	$frame->[FR_AGAIN]{time} = $_[0];
		592	}
		593
		594	sub counter($) {
		595	$frame->[FR_AGAIN]{time} = $_[0];
		596	$frame->[FR_STATE]{counter} + 0
		597	}
		598
		599	=back
		600
		601	=head2 SHAPE CHANGING OPERATORS
		602
		603	The following operators modify the shape, size or position of the image.
		604
		605	=over 4
		606
		607	=item clip $img
		608
		609	=item clip $width, $height, $img
		610
		611	=item clip $x, $y, $width, $height, $img
		612
		613	Clips an image to the given rectangle. If the rectangle is outside the
		614	image area (e.g. when C<$x> or C<$y> are negative) or the rectangle is
		615	larger than the image, then the tiling mode defines how the extra pixels
		616	will be filled.
		617
		618	If C<$x> and C<$y> are missing, then C<0> is assumed for both.
		619
		620	If C<$width> and C<$height> are missing, then the window size will be
		621	assumed.
		622
		623	Example: load an image, blur it, and clip it to the window size to save
		624	memory.
		625
		626	clip keep { blur 10, load "mybg.png" }
		627
		628	=cut
		629
		630	sub clip($;$$;$$) {
		631	my $img = pop;
		632	my $h = pop \|\| TH;
		633	my $w = pop \|\| TW;
		634	$img->sub_rect ($_[0], $_[1], $w, $h)
		635	}
		636
		637	=item scale $img
		638
		639	=item scale $size_factor, $img
		640
		641	=item scale $width_factor, $height_factor, $img
		642
		643	Scales the image by the given factors in horizontal
		644	(C<$width>) and vertical (C<$height>) direction.
		645
		646	If only one factor is given, it is used for both directions.
		647
		648	If no factors are given, scales the image to the window size without
		649	keeping aspect.
		650
		651	=item resize $width, $height, $img
		652
		653	Resizes the image to exactly C<$width> times C<$height> pixels.
		654
		655	=item fit $img
		656
		657	=item fit $width, $height, $img
		658
		659	Fits the image into the given C<$width> and C<$height> without changing
		660	aspect, or the terminal size. That means it will be shrunk or grown until
		661	the whole image fits into the given area, possibly leaving borders.
		662
		663	=item cover $img
		664
		665	=item cover $width, $height, $img
		666
		667	Similar to C<fit>, but shrinks or grows until all of the area is covered
		668	by the image, so instead of potentially leaving borders, it will cut off
		669	image data that doesn't fit.
		670
		671	=cut
		672
		673	sub scale($;$;$) {
		674	my $img = pop;
		675
		676	@_ == 2 ? $img->scale ($_[0] * $img->w, $_[1] * $img->h)
		677	: @_ ? $img->scale ($_[0] * $img->w, $_[0] * $img->h)
		678	: $img->scale (TW, TH)
		679	}
		680
33	sub resize {	681	sub resize($$$) {
34	$_[0]->scale ($_[1], $_[2])	682	my $img = pop;
		683	$img->scale ($_[0], $_[1])
35	}	684	}
36		685
		686	sub fit($;$$) {
		687	my $img = pop;
		688	my $w = ($_[0] \|\| TW) / $img->w;
		689	my $h = ($_[1] \|\| TH) / $img->h;
		690	scale +(min $w, $h), $img
		691	}
		692
		693	sub cover($;$$) {
		694	my $img = pop;
		695	my $w = ($_[0] \|\| TW) / $img->w;
		696	my $h = ($_[1] \|\| TH) / $img->h;
		697	scale +(max $w, $h), $img
		698	}
		699
		700	=item move $dx, $dy, $img
		701
		702	Moves the image by C<$dx> pixels in the horizontal, and C<$dy> pixels in
		703	the vertical.
		704
		705	Example: move the image right by 20 pixels and down by 30.
		706
		707	move 20, 30, ...
		708
		709	=item align $xalign, $yalign, $img
		710
		711	Aligns the image according to a factor - C<0> means the image is moved to
		712	the left or top edge (for C<$xalign> or C<$yalign>), C<0.5> means it is
		713	exactly centered and C<1> means it touches the right or bottom edge.
		714
		715	Example: remove any visible border around an image, center it vertically but move
		716	it to the right hand side.
		717
		718	align 1, 0.5, pad $img
		719
		720	=item center $img
		721
		722	=item center $width, $height, $img
		723
		724	Centers the image, i.e. the center of the image is moved to the center of
		725	the terminal window (or the box specified by C<$width> and C<$height> if
		726	given).
		727
		728	Example: load an image and center it.
		729
		730	center keep { pad load "mybg.png" }
		731
		732	=item rootalign $img
		733
		734	Moves the image so that it appears glued to the screen as opposed to the
		735	window. This gives the illusion of a larger area behind the window. It is
		736	exactly equivalent to C<move -TX, -TY>, that is, it moves the image to the
		737	top left of the screen.
		738
		739	Example: load a background image, put it in mirror mode and root align it.
		740
		741	rootalign keep { mirror load "mybg.png" }
		742
		743	Example: take the screen background and align it, giving the illusion of
		744	transparency as long as the window isn't in front of other windows.
		745
		746	rootalign root
		747
		748	=cut
		749
37	sub move {	750	sub move($$;$) {
38	# TODO: must be simpler	751	my $img = pop->clone;
39	$_[0]->transform ($_[0]->w, $_[0]->h, $_[1],	752	$img->move ($_[0], $_[1]);
40	1, 0, -$_[2],	753	$img
41	0, 1, -$_[3],	754	}
42	0, 0, 1,	755
		756	sub align($;$$) {
		757	my $img = pop;
		758
		759	move $_[0] * (TW - $img->w),
		760	$_[1] * (TH - $img->h),
		761	$img
		762	}
		763
		764	sub center($;$$) {
		765	my $img = pop;
		766	my $w = $_[0] \|\| TW;
		767	my $h = $_[1] \|\| TH;
		768
		769	move 0.5 * ($w - $img->w), 0.5 * ($h - $img->h), $img
		770	}
		771
		772	sub rootalign($) {
		773	move -TX, -TY, $_[0]
		774	}
		775
		776	=item rotate $center_x, $center_y, $degrees, $img
		777
		778	Rotates the image clockwise by C<$degrees> degrees, around the point at
		779	C<$center_x> and C<$center_y> (specified as factor of image width/height).
		780
		781	Example: rotate the image by 90 degrees around its center.
		782
		783	rotate 0.5, 0.5, 90, keep { load "$HOME/mybg.png" }
		784
		785	=cut
		786
		787	sub rotate($$$$) {
		788	my $img = pop;
		789	$img->rotate (
		790	$_[0] * ($img->w + $img->x),
		791	$_[1] * ($img->h + $img->y),
		792	$_[2] * (3.14159265 / 180),
43	)	793	)
44	}	794	}
45		795
46	sub rotate {	796	=back
47	$_[0]->rotate ($_[0], $_[1], $_[2], $_[3] * (3.14159265 / 180))
48	}
49		797
50	sub blur {	798	=head2 COLOUR MODIFICATIONS
51	my ($img, $rh, $rv) = @_;
52		799
53	$img = $img->clone;	800	The following operators change the pixels of the image.
54	$img->clone->blur ($rh, $rv);
55	$img
56	}
57		801
		802	=over 4
		803
		804	=item tint $color, $img
		805
		806	Tints the image in the given colour.
		807
		808	Example: tint the image red.
		809
		810	tint "red", load "rgb.png"
		811
		812	Example: the same, but specify the colour by component.
		813
		814	tint [1, 0, 0], load "rgb.png"
		815
		816	=cut
		817
		818	sub tint($$) {
		819	$_[1]->tint ($_[0])
		820	}
		821
		822	=item shade $factor, $img
		823
		824	Shade the image by the given factor.
		825
		826	=cut
		827
		828	sub shade($$) {
		829	$_[1]->shade ($_[0])
		830	}
		831
		832	=item contrast $factor, $img
		833
		834	=item contrast $r, $g, $b, $img
		835
		836	=item contrast $r, $g, $b, $a, $img
		837
		838	Adjusts the I<contrast> of an image.
		839
		840	The first form applies a single C<$factor> to red, green and blue, the
		841	second form applies separate factors to each colour channel, and the last
		842	form includes the alpha channel.
		843
		844	Values from 0 to 1 lower the contrast, values higher than 1 increase the
		845	contrast.
		846
		847	Due to limitations in the underlying XRender extension, lowering contrast
		848	also reduces brightness, while increasing contrast currently also
		849	increases brightness.
		850
		851	=item brightness $bias, $img
		852
		853	=item brightness $r, $g, $b, $img
		854
		855	=item brightness $r, $g, $b, $a, $img
		856
		857	Adjusts the brightness of an image.
		858
		859	The first form applies a single C<$bias> to red, green and blue, the
		860	second form applies separate biases to each colour channel, and the last
		861	form includes the alpha channel.
		862
		863	Values less than 0 reduce brightness, while values larger than 0 increase
		864	it. Useful range is from -1 to 1 - the former results in a black, the
		865	latter in a white picture.
		866
		867	Due to idiosyncrasies in the underlying XRender extension, biases less
		868	than zero can be I<very> slow.
		869
		870	You can also try the experimental(!) C<muladd> operator.
		871
		872	=cut
		873
58	sub contrast {	874	sub contrast($$;$$;$) {
		875	my $img = pop;
59	my ($img, $r, $g, $b, $a) = @_;	876	my ($r, $g, $b, $a) = @_;
		877
60	($g, $b) = ($r, $r) if @_ < 4;	878	($g, $b) = ($r, $r) if @_ < 3;
61	$a = 1 if @_ < 5;	879	$a = 1 if @_ < 4;
		880
62	$img = $img->clone;	881	$img = $img->clone;
63	$img->contrast ($r, $g, $b, $a);	882	$img->contrast ($r, $g, $b, $a);
64	$img	883	$img
65	}	884	}
66		885
67	sub brightness {	886	sub brightness($$;$$;$) {
		887	my $img = pop;
68	my ($img, $r, $g, $b, $a) = @_;	888	my ($r, $g, $b, $a) = @_;
		889
69	($g, $b) = ($r, $r) if @_ < 4;	890	($g, $b) = ($r, $r) if @_ < 3;
70	$a = 1 if @_ < 5;	891	$a = 1 if @_ < 4;
		892
71	$img = $img->clone;	893	$img = $img->clone;
72	$img->brightness ($r, $g, $b, $a);	894	$img->brightness ($r, $g, $b, $a);
73	$img	895	$img
74	}	896	}
75		897
76	sub x { $new->{position_sensitive} = 1; $x }	898	=item muladd $mul, $add, $img # EXPERIMENTAL
77	sub y { $new->{position_sensitive} = 1; $y }
78	sub w { $new->{size_sensitive} = 1; $w }
79	sub h { $new->{size_sensitive} = 1; $h }
80	sub now { urxvt::NOW }
81		899
82	sub again {	900	First multiplies the pixels by C<$mul>, then adds C<$add>. This can be used
83	$new->{again} = $_[0];	901	to implement brightness and contrast at the same time, with a wider value
		902	range than contrast and brightness operators.
		903
		904	Due to numerous bugs in XRender implementations, it can also introduce a
		905	number of visual artifacts.
		906
		907	Example: increase contrast by a factor of C<$c> without changing image
		908	brightness too much.
		909
		910	muladd $c, (1 - $c) * 0.5, $img
		911
		912	=cut
		913
		914	sub muladd($$$) {
		915	$_[2]->muladd ($_[0], $_[1])
		916	}
		917
		918	=item blur $radius, $img
		919
		920	=item blur $radius_horz, $radius_vert, $img
		921
		922	Gaussian-blurs the image with (roughly) C<$radius> pixel radius. The radii
		923	can also be specified separately.
		924
		925	Blurring is often I<very> slow, at least compared or other
		926	operators. Larger blur radii are slower than smaller ones, too, so if you
		927	don't want to freeze your screen for long times, start experimenting with
		928	low values for radius (<5).
		929
		930	=cut
		931
		932	sub blur($$;$) {
		933	my $img = pop;
		934	$img->blur ($_[0], @_ >= 2 ? $_[1] : $_[0])
		935	}
		936
		937	=back
		938
		939	=head2 OTHER STUFF
		940
		941	Anything that didn't fit any of the other categories, even after applying
		942	force and closing our eyes.
		943
		944	=over 4
		945
		946	=item keep { ... }
		947
		948	This operator takes a code block as argument, that is, one or more
		949	statements enclosed by braces.
		950
		951	The trick is that this code block is only evaluated when the outcome
		952	changes - on other calls the C<keep> simply returns the image it computed
		953	previously (yes, it should only be used with images). Or in other words,
		954	C<keep> I<caches> the result of the code block so it doesn't need to be
		955	computed again.
		956
		957	This can be extremely useful to avoid redoing slow operations - for
		958	example, if your background expression takes the root background, blurs it
		959	and then root-aligns it it would have to blur the root background on every
		960	window move or resize.
		961
		962	Another example is C<load>, which can be quite slow.
		963
		964	In fact, urxvt itself encloses the whole expression in some kind of
		965	C<keep> block so it only is reevaluated as required.
		966
		967	Putting the blur into a C<keep> block will make sure the blur is only done
		968	once, while the C<rootalign> is still done each time the window moves.
		969
		970	rootalign keep { blur 10, root }
		971
		972	This leaves the question of how to force reevaluation of the block,
		973	in case the root background changes: If expression inside the block
		974	is sensitive to some event (root background changes, window geometry
		975	changes), then it will be reevaluated automatically as needed.
		976
		977	=cut
		978
		979	sub keep(&) {
		980	my $id = $_[0]+0;
		981
		982	local $frame = $self->{frame_cache}{$id} \|\|= [$frame];
		983
		984	unless ($frame->[FR_CACHE]) {
		985	$frame->[FR_CACHE] = [ $_[0]() ];
		986
		987	my $self = $self;
		988	my $frame = $frame;
		989	Scalar::Util::weaken $frame;
		990	$self->compile_frame ($frame, sub {
		991	# clear this frame cache, also for all parents
		992	for (my $frame = $frame; $frame; $frame = $frame->[0]) {
		993	undef $frame->[FR_CACHE];
		994	}
		995
		996	$self->recalculate;
		997	});
		998	};
		999
		1000	# in scalar context we always return the first original result, which
		1001	# is not quite how perl works.
		1002	wantarray
		1003	? @{ $frame->[FR_CACHE] }
		1004	: $frame->[FR_CACHE][0]
		1005	}
		1006
		1007	# sub keep_clear() {
		1008	# delete $self->{frame_cache};
84	}	1009	# }
85		1010
86	sub counter {	1011	=back
87	$new->{again} = $_[0];	1012
88	$self->{counter}++ + 0	1013	=cut
89	}	1014
90	}	1015	}
91		1016
92	sub parse_expr {	1017	sub parse_expr {
93	my $expr = eval "sub {\npackage urxvt::bgdsl;\n#line 0 'background expression'\n$_[0]\n}";	1018	my $expr = eval
		1019	"sub {\n"
		1020	. "package urxvt::bgdsl;\n"
		1021	. "#line 0 'background expression'\n"
		1022	. "$_[0]\n"
		1023	. "}";
94	die if $@;	1024	die if $@;
95	$expr	1025	$expr
96	}	1026	}
97		1027
98	# compiles a parsed expression	1028	# compiles a parsed expression
99	sub set_expr {	1029	sub set_expr {
100	my ($self, $expr) = @_;	1030	my ($self, $expr) = @_;
101		1031
102	local $Data::Dumper::Deparse=1; use Data::Dumper; warn Dumper $expr;#d#	1032	$self->{root} = []; # the outermost frame
103	$self->{expr} = $expr;	1033	$self->{expr} = $expr;
104	$self->recalculate;	1034	$self->recalculate;
105	}	1035	}
106		1036
		1037	# takes a hash of sensitivity indicators and installs watchers
		1038	sub compile_frame {
		1039	my ($self, $frame, $cb) = @_;
		1040
		1041	my $state = $frame->[urxvt::bgdsl::FR_STATE] \|\|= {};
		1042	my $again = $frame->[urxvt::bgdsl::FR_AGAIN];
		1043
		1044	# don't keep stuff alive
		1045	Scalar::Util::weaken $state;
		1046
		1047	if ($again->{nested}) {
		1048	$state->{nested} = 1;
		1049	} else {
		1050	delete $state->{nested};
		1051	}
		1052
		1053	if (my $interval = $again->{time}) {
		1054	$state->{time} = [$interval, urxvt::timer->new->after ($interval)->interval ($interval)]
		1055	if $state->{time}[0] != $interval;
		1056
		1057	# callback might have changed, although we could just rule that out
		1058	$state->{time}[1]->cb (sub {
		1059	++$state->{counter};
		1060	$cb->();
		1061	});
		1062	} else {
		1063	delete $state->{time};
		1064	}
		1065
		1066	if ($again->{position}) {
		1067	$state->{position} = $self->on (position_change => $cb);
		1068	} else {
		1069	delete $state->{position};
		1070	}
		1071
		1072	if ($again->{size}) {
		1073	$state->{size} = $self->on (size_change => $cb);
		1074	} else {
		1075	delete $state->{size};
		1076	}
		1077
		1078	if ($again->{rootpmap}) {
		1079	$state->{rootpmap} = $self->on (rootpmap_change => $cb);
		1080	} else {
		1081	delete $state->{rootpmap};
		1082	}
		1083	}
		1084
107	# evaluate the current bg expression	1085	# evaluate the current bg expression
108	sub recalculate {	1086	sub recalculate {
109	my ($self) = @_;	1087	my ($arg_self) = @_;
110		1088
111	local $urxvt::bgdsl::vars::self = $self;	1089	# rate limit evaluation
112		1090
113	local $urxvt::bgdsl::vars::old = $self->{state};	1091	if ($arg_self->{next_refresh} > urxvt::NOW) {
114	local $urxvt::bgdsl::vars::new = my $state = $self->{state} = {};	1092	$arg_self->{next_refresh_timer} = urxvt::timer->new->after ($arg_self->{next_refresh} - urxvt::NOW)->cb (sub {
		1093	$arg_self->recalculate;
		1094	});
		1095	return;
		1096	}
115		1097
116	($urxvt::bgdsl::vars::x, $urxvt::bgdsl::vars::y, $urxvt::bgdsl::vars::w, $urxvt::bgdsl::vars::h) =	1098	$arg_self->{next_refresh} = urxvt::NOW + $MIN_INTERVAL;
117	$self->get_geometry;
118		1099
		1100	# set environment to evaluate user expression
		1101
		1102	local $self = $arg_self;
		1103	local $HOME = $ENV{HOME};
		1104	local $frame = $self->{root};
		1105
		1106	($x, $y, $w, $h) = $self->background_geometry ($self->{border});
		1107
		1108	# evaluate user expression
		1109
119	my $img = eval { $self->{expr}->() };	1110	my @img = eval { $self->{expr}->() };
120	warn $@ if $@;#d#	1111	die $@ if $@;
		1112	die "background-expr did not return anything.\n" unless @img;
		1113	die "background-expr: expected image(s), got something else.\n"
		1114	if grep { !UNIVERSAL::isa $_, "urxvt::img" } @img;
121		1115
122	if (my $again = $state->{again}) {	1116	my $img = urxvt::bgdsl::merge @img;
123	warn $again;#d#	1117
124	$state->{again} = urxvt::timer->new->after ($again)->cb (sub { $self->recalculate });	1118	$frame->[FR_AGAIN]{size} = 1
		1119	if $img->repeat_mode != urxvt::RepeatNormal;
		1120
		1121	# if the expression is sensitive to external events, prepare reevaluation then
		1122	$self->compile_frame ($frame, sub { $arg_self->recalculate });
		1123
		1124	# clear stuff we no longer need
		1125
		1126	# unless (%{ $frame->[FR_STATE] }) {
		1127	# delete $self->{state};
		1128	# delete $self->{expr};
125	}	1129	# }
126		1130
127	# TODO: install handlers for geometry changes &c	1131	# set background pixmap
128		1132
129	warn $img;
130	$self->set_background ($img);	1133	$self->set_background ($img, $self->{border});
131	$self->scr_recolour (0);	1134	$self->scr_recolour (0);
132	$self->want_refresh;	1135	$self->want_refresh;
133	}	1136	}
134		1137
135	sub on_start {	1138	sub on_start {
136	my ($self) = @_;	1139	my ($self) = @_;
137		1140
		1141	my $expr = $self->x_resource ("%.expr")
		1142	or return;
		1143
		1144	$self->has_render
		1145	or die "background extension needs RENDER extension 0.10 or higher, ignoring background-expr.\n";
		1146
138	$self->set_expr (parse_expr $EXPR);	1147	$self->set_expr (parse_expr $expr);
		1148	$self->{border} = $self->x_resource_boolean ("%.border");
		1149
		1150	$MIN_INTERVAL = $self->x_resource ("%.interval");
139		1151
140	()	1152	()
141	}	1153	}
142		1154

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Comparing rxvt-unicode/src/perl/background (file contents): Revision 1.1 by root, Mon Jun 4 21:39:56 2012 UTC vs. Revision 1.82 by sf-exg, Sat Jan 19 10:04:34 2013 UTC

Diff Legend

Comparing rxvt-unicode/src/perl/background (file contents):
Revision 1.1 by root, Mon Jun 4 21:39:56 2012 UTC vs.
Revision 1.82 by sf-exg, Sat Jan 19 10:04:34 2013 UTC