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

Comparing rxvt-unicode/src/perl/background (file contents):
Revision 1.23 by root, Thu Jun 7 10:22:55 2012 UTC vs.
Revision 1.69 by root, Mon Jul 2 01:32:26 2012 UTC

1	#! perl	1	#! perl
2		2
3	#:META:X_RESOURCE:%.expr:string:background expression	3	#:META:X_RESOURCE:%.expr:string:background expression
4	#:META:X_RESOURCE:%.enable:boolean:some boolean	4	#:META:X_RESOURCE:%.border:boolean:respect the terminal border
5	#:META:X_RESOURCE:%.extra.:value:extra config	5	#:META:X_RESOURCE:%.interval:seconds:minimum time between updates
6		6
7	our $EXPR = 'clip move -X, -Y, load "MagnoliaAlpha.png"';	7	=head1 NAME
8	#$EXPR = '
9	# rotate W, H, 50, 50, counter 1/59.95, repeat_mirror,
10	# clip X, Y, W, H, repeat_mirror,
11	# load "/root/pix/das_fette_schwein.jpg"
12	#';
13	#$EXPR = 'solid "red"';
14	#$EXPR = 'blur root, 10, 10'
15	#$EXPR = 'blur move (root, -x, -y), 5, 5'
16	#resize load "/root/pix/das_fette_schwein.jpg", w, h
17		8
18	use Safe;	9	background - manage terminal background
19		10
20	our ($bgdsl_self, $old, $new);	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 keep { load "/path/to/mybg.png" }'
		32
		33	Or specified as a X resource:
		34
		35	URxvt.background-expr: scale keep { 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 keep { load "$HOME/mybg.png"
		59	}> scales the image to the window size, so it relies on the window size
		60	and will be reevaluated each time it is changed, but not when it moves for
		61	example. That ensures that the picture always fills the terminal, even
		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	scale keep {
		70	again 3600;
		71	if (localtime now)[6]) {
		72	return load "$HOME/weekday.png";
		73	} else {
		74	return load "$HOME/sunday.png";
		75	}
		76	}
		77
		78	This inner expression is evaluated once per hour (and whenever the
		79	temrinal window is resized). It sets F<sunday.png> as background on
		80	Sundays, and F<weekday.png> on all other days.
		81
		82	Fortunately, we expect that most expressions will be much simpler, with
		83	little Perl knowledge needed.
		84
		85	Basically, you always start with a function that "generates" an image
		86	object, such as C<load>, which loads an image from disk, or C<root>, which
		87	returns the root window background image:
		88
		89	load "$HOME/mypic.png"
		90
		91	The path is usually specified as a quoted string (the exact rules can be
		92	found in the L<perlop> manpage). The F<$HOME> at the beginning of the
		93	string is expanded to the home directory.
		94
		95	Then you prepend one or more modifiers or filtering expressions, such as
		96	C<scale>:
		97
		98	scale load "$HOME/mypic.png"
		99
		100	Just like a mathematical expression with functions, you should read these
		101	expressions from right to left, as the C<load> is evaluated first, and
		102	its result becomes the argument to the C<scale> function.
		103
		104	Many operators also allow some parameters preceding the input image
		105	that modify its behaviour. For example, C<scale> without any additional
		106	arguments scales the image to size of the terminal window. If you specify
		107	an additional argument, it uses it as a scale factor (multiply by 100 to
		108	get a percentage):
		109
		110	scale 2, load "$HOME/mypic.png"
		111
		112	This enlarges the image by a factor of 2 (200%). As you can see, C<scale>
		113	has now two arguments, the C<200> and the C<load> expression, while
		114	C<load> only has one argument. Arguments are separated from each other by
		115	commas.
		116
		117	Scale also accepts two arguments, which are then separate factors for both
		118	horizontal and vertical dimensions. For example, this halves the image
		119	width and doubles the image height:
		120
		121	scale 0.5, 2, load "$HOME/mypic.png"
		122
		123	IF you try out these expressions, you might suffer from some sluggishness,
		124	because each time the terminal is resized, it loads the PNG image agin
		125	and scales it. Scaling is usually fast (and unavoidable), but loading the
		126	image can be quite time consuming. This is where C<keep> comes in handy:
		127
		128	scale 0.5, 2, keep { load "$HOME/mypic.png" }
		129
		130	The C<keep> operator executes all the statements inside the braces only
		131	once, or when it thinks the outcome might change. In other cases it
		132	returns the last value computed by the brace block.
		133
		134	This means that the C<load> is only executed once, which makes it much
		135	faster, but also means that more memory is being used, because the loaded
		136	image must be kept in memory at all times. In this expression, the
		137	trade-off is likely worth it.
		138
		139	But back to effects: Other effects than scaling are also readily
		140	available, for example, you can tile the image to fill the whole window,
		141	instead of resizing it:
		142
		143	tile keep { load "$HOME/mypic.png" }
		144
		145	In fact, images returned by C<load> are in C<tile> mode by default, so the
		146	C<tile> operator is kind of superfluous.
		147
		148	Another common effect is to mirror the image, so that the same edges
		149	touch:
		150
		151	mirror keep { load "$HOME/mypic.png" }
		152
		153	Another common background expression is:
		154
		155	rootalign root
		156
		157	This one first takes a snapshot of the screen background image, and then
		158	moves it to the upper left corner of the screen (as opposed to the upper
		159	left corner of the terminal window)- the result is pseudo-transparency:
		160	the image seems to be static while the window is moved around.
		161
		162	=head2 CACHING AND SENSITIVITY
		163
		164	Since some operations (such as C<load> and C<blur>) can take a long time,
		165	caching results can be very important for a smooth operation. Caching can
		166	also be useful to reduce memory usage, though, for example, when an image
		167	is cached by C<load>, it could be shared by multiple terminal windows
		168	running inside urxvtd.
		169
		170	=head3 C<keep { ... }> caching
		171
		172	The most important way to cache expensive operations is to use C<keep {
		173	... }>. The C<keep> operator takes a block of multiple statements enclosed
		174	by C<{}> and keeps the return value in memory.
		175
		176	An expression can be "sensitive" to various external events, such as
		177	scaling or moving the window, root background changes and timers. Simply
		178	using an expression (such as C<scale> without parameters) that depends on
		179	certain changing values (called "variables"), or using those variables
		180	directly, will make an expression sensitive to these events - for example,
		181	using C<scale> or C<TW> will make the expression sensitive to the terminal
		182	size, and thus to resizing events.
		183
		184	When such an event happens, C<keep> will automatically trigger a
		185	reevaluation of the whole expression with the new value of the expression.
		186
		187	C<keep> is most useful for expensive operations, such as C<blur>:
		188
		189	rootalign keep { blur 20, root }
		190
		191	This makes a blurred copy of the root background once, and on subsequent
		192	calls, just root-aligns it. Since C<blur> is usually quite slow and
		193	C<rootalign> is quite fast, this trades extra memory (for the cached
		194	blurred pixmap) with speed (blur only needs to be redone when root
		195	changes).
		196
		197	=head3 C<load> caching
		198
		199	The C<load> operator itself does not keep images in memory, but as long as
		200	the image is still in memory, C<load> will use the in-memory image instead
		201	of loading it freshly from disk.
		202
		203	That means that this expression:
		204
		205	keep { load "$HOME/path..." }
		206
		207	Not only caches the image in memory, other terminal instances that try to
		208	C<load> it can reuse that in-memory copy.
		209
		210	=head1 REFERENCE
		211
		212	=head2 COMMAND LINE SWITCHES
		213
		214	=over 4
		215
		216	=item --background-expr perl-expression
		217
		218	Specifies the Perl expression to evaluate.
		219
		220	=item --background-border
		221
		222	By default, the expression creates an image that fills the full window,
		223	overwriting borders and any other areas, such as the scrollbar.
		224
		225	Specifying this flag changes the behaviour, so that the image only
		226	replaces the background of the character area.
		227
		228	=item --background-interval seconds
		229
		230	Since some operations in the underlying XRender extension can effectively
		231	freeze your X-server for prolonged time, this extension enforces a minimum
		232	time between updates, which is normally about 0.1 seconds.
		233
		234	If you want to do updates more often, you can decrease this safety
		235	interval with this switch.
		236
		237	=back
		238
		239	=cut
		240
		241	our %_IMG_CACHE;
		242	our $HOME;
		243	our ($self, $frame);
21	our ($l, $t, $w, $h);	244	our ($x, $y, $w, $h);
22		245
23	# enforce at least this interval between updates	246	# enforce at least this interval between updates
24	our $MIN_INTERVAL = 1/100;	247	our $MIN_INTERVAL = 6/59.951;
25		248
26	{	249	{
27	package urxvt::bgdsl; # background language	250	package urxvt::bgdsl; # background language
28		251
29	# *repeat_empty = \&urxvt::RepeatNone;	252	sub FR_PARENT() { 0 } # parent frame, if any - must be #0
30	# *repeat_tile = \&urxvt::RepeatNormal;	253	sub FR_CACHE () { 1 } # cached values
31	# *repeat_pad = \&urxvt::RepeatPad;	254	sub FR_AGAIN () { 2 } # what this expr is sensitive to
32	# *repeat_mirror = \&urxvt::RepeatReflect;	255	sub FR_STATE () { 3 } # watchers etc.
		256
		257	use List::Util qw(min max sum shuffle);
33		258
34	=head2 PROVIDERS/GENERATORS	259	=head2 PROVIDERS/GENERATORS
35		260
		261	These functions provide an image, by loading it from disk, grabbing it
		262	from the root screen or by simply generating it. They are used as starting
		263	points to get an image you can play with.
		264
36	=over 4	265	=over 4
37		266
38	=item load $path	267	=item load $path
		268
		269	Loads the image at the given C<$path>. The image is set to plane tiling
		270	mode.
		271
		272	If the image is already in memory (e.g. because another terminal instance
		273	uses it), then the in-memory copy us returned instead.
		274
		275	=item load_uc $path
		276
		277	Load uncached - same as load, but does not cache the image, which means it
		278	is I<always> loaded from the filesystem again.
39		279
40	=cut	280	=cut
41		281
42	sub load($) {	282	sub load($) {
43	my ($path) = @_;	283	my ($path) = @_;
44		284
45	$new->{load}{$path} = $old->{load}{$path} \|\| $bgdsl_self->new_img_from_file ($path);	285	$_IMG_CACHE{$path} \|\| do {
		286	my $img = $self->new_img_from_file ($path);
		287	Scalar::Util::weaken ($_IMG_CACHE{$path} = $img);
		288	$img
		289	}
46	}	290	}
		291
		292	=item root
		293
		294	Returns the root window pixmap, that is, hopefully, the background image
		295	of your screen.
		296
		297	This function makes your expression root sensitive, that means it will be
		298	reevaluated when the bg image changes.
		299
		300	=cut
47		301
48	sub root() {	302	sub root() {
49	$new->{rootpmap_sensitive} = 1;	303	$frame->[FR_AGAIN]{rootpmap} = 1;
50	die "root op not supported, exg, we need you";	304	$self->new_img_from_root
51	}	305	}
		306
		307	=item solid $colour
		308
		309	=item solid $width, $height, $colour
		310
		311	Creates a new image and completely fills it with the given colour. The
		312	image is set to tiling mode.
		313
		314	If C<$width> and C<$height> are omitted, it creates a 1x1 image, which is
		315	useful for solid backgrounds or for use in filtering effects.
		316
		317	=cut
52		318
53	sub solid($;$$) {	319	sub solid($;$$) {
		320	my $colour = pop;
		321
54	my $img = $bgdsl_self->new_img (urxvt::PictStandardARGB32, $_[1] \|\| 1, $_[2] \|\| 1);	322	my $img = $self->new_img (urxvt::PictStandardARGB32, 0, 0, $_[0] \|\| 1, $_[1] \|\| 1);
55	$img->fill ($_[0]);	323	$img->fill ($colour);
56	$img	324	$img
57	}	325	}
58		326
		327	=item clone $img
		328
		329	Returns an exact copy of the image. This is useful if you want to have
		330	multiple copies of the same image to apply different effects to.
		331
		332	=cut
		333
		334	sub clone($) {
		335	$_[0]->clone
		336	}
		337
		338	=item merge $img ...
		339
		340	Takes any number of images and merges them together, creating a single
		341	image containing them all. The tiling mode of the first image is used as
		342	the tiling mode of the resulting image.
		343
		344	This function is called automatically when an expression returns multiple
		345	images.
		346
		347	=cut
		348
		349	sub merge(@) {
		350	return $_[0] unless $#_;
		351
		352	# rather annoyingly clumsy, but optimisation is for another time
		353
		354	my $x0 = +1e9;
		355	my $y0 = +1e9;
		356	my $x1 = -1e9;
		357	my $y1 = -1e9;
		358
		359	for (@_) {
		360	my ($x, $y, $w, $h) = $_->geometry;
		361
		362	$x0 = $x if $x0 > $x;
		363	$y0 = $y if $y0 > $y;
		364
		365	$x += $w;
		366	$y += $h;
		367
		368	$x1 = $x if $x1 < $x;
		369	$y1 = $y if $y1 < $y;
		370	}
		371
		372	my $base = $self->new_img (urxvt::PictStandardARGB32, $x0, $y0, $x1 - $x0, $y1 - $y0);
		373	$base->repeat_mode ($_[0]->repeat_mode);
		374	$base->fill ([0, 0, 0, 0]);
		375
		376	$base->draw ($_)
		377	for @_;
		378
		379	$base
		380	}
		381
		382	=head2 TILING MODES
		383
		384	The following operators modify the tiling mode of an image, that is, the
		385	way that pixels outside the image area are painted when the image is used.
		386
		387	=over 4
		388
		389	=item tile $img
		390
		391	Tiles the whole plane with the image and returns this new image - or in
		392	other words, it returns a copy of the image in plane tiling mode.
		393
		394	Example: load an image and tile it over the background, without
		395	resizing. The C<tile> call is superfluous because C<load> already defaults
		396	to tiling mode.
		397
		398	tile load "mybg.png"
		399
		400	=item mirror $img
		401
		402	Similar to tile, but reflects the image each time it uses a new copy, so
		403	that top edges always touch top edges, right edges always touch right
		404	edges and so on (with normal tiling, left edges always touch right edges
		405	and top always touch bottom edges).
		406
		407	Example: load an image and mirror it over the background, avoiding sharp
		408	edges at the image borders at the expense of mirroring the image itself
		409
		410	mirror load "mybg.png"
		411
		412	=item pad $img
		413
		414	Takes an image and modifies it so that all pixels outside the image area
		415	become transparent. This mode is most useful when you want to place an
		416	image over another image or the background colour while leaving all
		417	background pixels outside the image unchanged.
		418
		419	Example: load an image and display it in the upper left corner. The rest
		420	of the space is left "empty" (transparent or whatever your compositor does
		421	in alpha mode, else background colour).
		422
		423	pad load "mybg.png"
		424
		425	=item extend $img
		426
		427	Extends the image over the whole plane, using the closest pixel in the
		428	area outside the image. This mode is mostly useful when you use more complex
		429	filtering operations and want the pixels outside the image to have the
		430	same values as the pixels near the edge.
		431
		432	Example: just for curiosity, how does this pixel extension stuff work?
		433
		434	extend move 50, 50, load "mybg.png"
		435
		436	=cut
		437
		438	sub pad($) {
		439	my $img = $_[0]->clone;
		440	$img->repeat_mode (urxvt::RepeatNone);
		441	$img
		442	}
		443
		444	sub tile($) {
		445	my $img = $_[0]->clone;
		446	$img->repeat_mode (urxvt::RepeatNormal);
		447	$img
		448	}
		449
		450	sub mirror($) {
		451	my $img = $_[0]->clone;
		452	$img->repeat_mode (urxvt::RepeatReflect);
		453	$img
		454	}
		455
		456	sub extend($) {
		457	my $img = $_[0]->clone;
		458	$img->repeat_mode (urxvt::RepeatPad);
		459	$img
		460	}
		461
59	=back	462	=back
60		463
61	=head2 VARIABLES	464	=head2 VARIABLE VALUES
		465
		466	The following functions provide variable data such as the terminal window
		467	dimensions. They are not (Perl-) variables, they just return stuff that
		468	varies. Most of them make your expression sensitive to some events, for
		469	example using C<TW> (terminal width) means your expression is evaluated
		470	again when the terminal is resized.
62		471
63	=over 4	472	=over 4
64		473
65	=cut	474	=item TX
66		475
67	sub X() { $new->{position_sensitive} = 1; $l }	476	=item TY
68	sub Y() { $new->{position_sensitive} = 1; $t }	477
69	sub W() { $new->{size_sensitive} = 1; $w }	478	Return the X and Y coordinates of the terminal window (the terminal
70	sub H() { $new->{size_sensitive} = 1; $h }	479	window is the full window by default, and the character area only when in
		480	border-respect mode).
		481
		482	Using these functions make your expression sensitive to window moves.
		483
		484	These functions are mainly useful to align images to the root window.
		485
		486	Example: load an image and align it so it looks as if anchored to the
		487	background (that's exactly what C<rootalign> does btw.):
		488
		489	move -TX, -TY, keep { load "mybg.png" }
		490
		491	=item TW
		492
		493	Return the width (C<TW>) and height (C<TH>) of the terminal window (the
		494	terminal window is the full window by default, and the character area only
		495	when in border-respect mode).
		496
		497	Using these functions make your expression sensitive to window resizes.
		498
		499	These functions are mainly useful to scale images, or to clip images to
		500	the window size to conserve memory.
		501
		502	Example: take the screen background, clip it to the window size, blur it a
		503	bit, align it to the window position and use it as background.
		504
		505	clip move -TX, -TY, keep { blur 5, root }
		506
		507	=cut
		508
		509	sub TX() { $frame->[FR_AGAIN]{position} = 1; $x }
		510	sub TY() { $frame->[FR_AGAIN]{position} = 1; $y }
		511	sub TW() { $frame->[FR_AGAIN]{size} = 1; $w }
		512	sub TH() { $frame->[FR_AGAIN]{size} = 1; $h }
		513
		514	=item now
		515
		516	Returns the current time as (fractional) seconds since the epoch.
		517
		518	Using this expression does I<not> make your expression sensitive to time,
		519	but the next two functions do.
		520
		521	=item again $seconds
		522
		523	When this function is used the expression will be reevaluated again in
		524	C<$seconds> seconds.
		525
		526	Example: load some image and rotate it according to the time of day (as if it were
		527	the hour pointer of a clock). Update this image every minute.
		528
		529	again 60;
		530	rotate 50, 50, (now % 86400) * -72 / 8640, scale keep { load "myclock.png" }
		531
		532	=item counter $seconds
		533
		534	Like C<again>, but also returns an increasing counter value, starting at
		535	0, which might be useful for some simple animation effects.
		536
		537	=cut
71		538
72	sub now() { urxvt::NOW }	539	sub now() { urxvt::NOW }
73		540
74	sub again($) {	541	sub again($) {
75	$new->{again} = $_[0];	542	$frame->[FR_AGAIN]{time} = $_[0];
76	}	543	}
77		544
78	sub counter($) {	545	sub counter($) {
79	$new->{again} = $_[0];	546	$frame->[FR_AGAIN]{time} = $_[0];
80	$bgdsl_self->{counter} + 0	547	$frame->[FR_STATE]{counter} + 0
81	}	548	}
82		549
83	=back	550	=back
84		551
85	=head2 OPERATORS	552	=head2 SHAPE CHANGING OPERATORS
		553
		554	The following operators modify the shape, size or position of the image.
86		555
87	=over 4	556	=over 4
88		557
89	=cut	558	=item clip $img
90		559
91	# sub clone($) {	560	=item clip $width, $height, $img
92	# $_[0]->clone	561
93	# }	562	=item clip $x, $y, $width, $height, $img
		563
		564	Clips an image to the given rectangle. If the rectangle is outside the
		565	image area (e.g. when C<$x> or C<$y> are negative) or the rectangle is
		566	larger than the image, then the tiling mode defines how the extra pixels
		567	will be filled.
		568
		569	If C<$x> an C<$y> are missing, then C<0> is assumed for both.
		570
		571	If C<$width> and C<$height> are missing, then the window size will be
		572	assumed.
		573
		574	Example: load an image, blur it, and clip it to the window size to save
		575	memory.
		576
		577	clip keep { blur 10, load "mybg.png" }
		578
		579	=cut
94		580
95	sub clip($;$$;$$) {	581	sub clip($;$$;$$) {
96	my $img = pop;	582	my $img = pop;
97	my $h = pop \|\| H;	583	my $h = pop \|\| TH;
98	my $w = pop \|\| W;	584	my $w = pop \|\| TW;
99	$img->sub_rect ($_[0], $_[1], $w, $h)	585	$img->sub_rect ($_[0], $_[1], $w, $h)
		586	}
		587
		588	=item scale $img
		589
		590	=item scale $size_factor, $img
		591
		592	=item scale $width_factor, $height_factor, $img
		593
		594	Scales the image by the given factors in horizontal
		595	(C<$width>) and vertical (C<$height>) direction.
		596
		597	If only one factor is give, it is used for both directions.
		598
		599	If no factors are given, scales the image to the window size without
		600	keeping aspect.
		601
		602	=item resize $width, $height, $img
		603
		604	Resizes the image to exactly C<$width> times C<$height> pixels.
		605
		606	=item fit $img
		607
		608	=item fit $width, $height, $img
		609
		610	Fits the image into the given C<$width> and C<$height> without changing
		611	aspect, or the terminal size. That means it will be shrunk or grown until
		612	the whole image fits into the given area, possibly leaving borders.
		613
		614	=item cover $img
		615
		616	=item cover $width, $height, $img
		617
		618	Similar to C<fit>, but shrinks or grows until all of the area is covered
		619	by the image, so instead of potentially leaving borders, it will cut off
		620	image data that doesn't fit.
		621
		622	=cut
		623
		624	sub scale($;$;$) {
		625	my $img = pop;
		626
		627	@_ == 2 ? $img->scale ($_[0] * $img->w, $_[1] * $img->h)
		628	: @_ ? $img->scale ($_[0] * $img->w, $_[0] * $img->h)
		629	: $img->scale (TW, TH)
100	}	630	}
101		631
102	sub resize($$$) {	632	sub resize($$$) {
103	my $img = pop;	633	my $img = pop;
104	$img->scale ($_[0], $_[1])	634	$img->scale ($_[0], $_[1])
105	}	635	}
106		636
107	# TODO: ugly	637	sub fit($;$$) {
		638	my $img = pop;
		639	my $w = ($_[0] \|\| TW) / $img->w;
		640	my $h = ($_[1] \|\| TH) / $img->h;
		641	scale +(min $w, $h), $img
		642	}
		643
		644	sub cover($;$$) {
		645	my $img = pop;
		646	my $w = ($_[0] \|\| TW) / $img->w;
		647	my $h = ($_[1] \|\| TH) / $img->h;
		648	scale +(max $w, $h), $img
		649	}
		650
		651	=item move $dx, $dy, $img
		652
		653	Moves the image by C<$dx> pixels in the horizontal, and C<$dy> pixels in
		654	the vertical.
		655
		656	Example: move the image right by 20 pixels and down by 30.
		657
		658	move 20, 30, ...
		659
		660	=item align $xalign, $yalign, $img
		661
		662	Aligns the image according to a factor - C<0> means the image is moved to
		663	the left or top edge (for C<$xalign> or C<$yalign>), C<0.5> means it is
		664	exactly centered and C<1> means it touches the right or bottom edge.
		665
		666	Example: remove any visible border around an image, center it vertically but move
		667	it to the right hand side.
		668
		669	align 1, 0.5, pad $img
		670
		671	=item center $img
		672
		673	=item center $width, $height, $img
		674
		675	Centers the image, i.e. the center of the image is moved to the center of
		676	the terminal window (or the box specified by C<$width> and C<$height> if
		677	given).
		678
		679	Example: load an image and center it.
		680
		681	center keep { pad load "mybg.png" }
		682
		683	=item rootalign $img
		684
		685	Moves the image so that it appears glued to the screen as opposed to the
		686	window. This gives the illusion of a larger area behind the window. It is
		687	exactly equivalent to C<move -TX, -TY>, that is, it moves the image to the
		688	top left of the screen.
		689
		690	Example: load a background image, put it in mirror mode and root align it.
		691
		692	rootalign keep { mirror load "mybg.png" }
		693
		694	Example: take the screen background and align it, giving the illusion of
		695	transparency as long as the window isn't in front of other windows.
		696
		697	rootalign root
		698
		699	=cut
		700
108	sub move($$;$) {	701	sub move($$;$) {
109	my $img = pop->clone;	702	my $img = pop->clone;
110	$img->move ($_[0], $_[1]);	703	$img->move ($_[0], $_[1]);
111	$img	704	$img
		705	}
		706
		707	sub align($;$$) {
112	# my $img = pop;	708	my $img = pop;
113	# $img->sub_rect (
114	# $_[0], $_[1],
115	# $img->w, $img->h,
116	# $_[2],
117	# )
118	}
119		709
		710	move $_[0] * (TW - $img->w),
		711	$_[1] * (TH - $img->h),
		712	$img
		713	}
		714
		715	sub center($;$$) {
		716	my $img = pop;
		717	my $w = $_[0] \|\| TW;
		718	my $h = $_[1] \|\| TH;
		719
		720	move 0.5 * ($w - $img->w), 0.5 * ($h - $img->h), $img
		721	}
		722
		723	sub rootalign($) {
		724	move -TX, -TY, $_[0]
		725	}
		726
		727	=item rotate $center_x, $center_y, $degrees, $img
		728
		729	Rotates the image clockwise by C<$degrees> degrees, around the point at
		730	C<$center_x> and C<$center_y> (specified as factor of image width/height).
		731
		732	Example: rotate the image by 90 degrees around it's center.
		733
		734	rotate 0.5, 0.5, 90, keep { load "$HOME/mybg.png" }
		735
		736	=cut
		737
120	sub rotate($$$$$$) {	738	sub rotate($$$$) {
121	my $img = pop;	739	my $img = pop;
122	$img->rotate (	740	$img->rotate (
123	$_[0],	741	$_[0] * ($img->w + $img->x),
124	$_[1],	742	$_[1] * ($img->h + $img->y),
125	$_[2] * $img->w * .01,
126	$_[3] * $img->h * .01,
127	$_[4] * (3.14159265 / 180),	743	$_[2] * (3.14159265 / 180),
128	)	744	)
129	}	745	}
130		746
131	sub blur($$$) {	747	=back
132	my ($rh, $rv, $img) = @_;
133		748
134	$img->blur ($rh, $rv);	749	=head2 COLOUR MODIFICATIONS
135	}	750
		751	The following operators change the pixels of the image.
		752
		753	=over 4
		754
		755	=item contrast $factor, $img
		756
		757	=item contrast $r, $g, $b, $img
		758
		759	=item contrast $r, $g, $b, $a, $img
		760
		761	Adjusts the I<contrast> of an image.
		762
		763	The first form applies a single C<$factor> to red, green and blue, the
		764	second form applies separate factors to each colour channel, and the last
		765	form includes the alpha channel.
		766
		767	Values from 0 to 1 lower the contrast, values higher than 1 increase the
		768	contrast.
		769
		770	Due to limitations in the underlying XRender extension, lowering contrast
		771	also reduces brightness, while increasing contrast currently also
		772	increases brightness.
		773
		774	=item brightness $bias, $img
		775
		776	=item brightness $r, $g, $b, $img
		777
		778	=item brightness $r, $g, $b, $a, $img
		779
		780	Adjusts the brightness of an image.
		781
		782	The first form applies a single C<$bias> to red, green and blue, the
		783	second form applies separate biases to each colour channel, and the last
		784	form includes the alpha channel.
		785
		786	Values less than 0 reduce brightness, while values larger than 0 increase
		787	it. Useful range is from -1 to 1 - the former results in a black, the
		788	latter in a white picture.
		789
		790	Due to idiosyncrasies in the underlying XRender extension, biases less
		791	than zero can be I<very> slow.
		792
		793	=cut
136		794
137	sub contrast($$;$$;$) {	795	sub contrast($$;$$;$) {
138	my $img = pop;	796	my $img = pop;
139	my ($r, $g, $b, $a) = @_;	797	my ($r, $g, $b, $a) = @_;
140		798
141	($g, $b) = ($r, $r) if @_ < 4;	799	($g, $b) = ($r, $r) if @_ < 3;
142	$a = 1 if @_ < 5;	800	$a = 1 if @_ < 4;
143		801
144	$img = $img->clone;	802	$img = $img->clone;
145	$img->contrast ($r, $g, $b, $a);	803	$img->contrast ($r, $g, $b, $a);
146	$img	804	$img
147	}	805	}
148		806
149	sub brightness($$;$$;$) {	807	sub brightness($$;$$;$) {
150	my $img = pop;	808	my $img = pop;
151	my ($r, $g, $b, $a) = @_;	809	my ($r, $g, $b, $a) = @_;
152		810
153	($g, $b) = ($r, $r) if @_ < 4;	811	($g, $b) = ($r, $r) if @_ < 3;
154	$a = 1 if @_ < 5;	812	$a = 1 if @_ < 4;
155		813
156	$img = $img->clone;	814	$img = $img->clone;
157	$img->brightness ($r, $g, $b, $a);	815	$img->brightness ($r, $g, $b, $a);
158	$img	816	$img
159	}	817	}
160		818
		819	=item blur $radius, $img
		820
		821	=item blur $radius_horz, $radius_vert, $img
		822
		823	Gaussian-blurs the image with (roughly) C<$radius> pixel radius. The radii
		824	can also be specified separately.
		825
		826	Blurring is often I<very> slow, at least compared or other
		827	operators. Larger blur radii are slower than smaller ones, too, so if you
		828	don't want to freeze your screen for long times, start experimenting with
		829	low values for radius (<5).
		830
		831	=cut
		832
		833	sub blur($$;$) {
		834	my $img = pop;
		835	$img->blur ($_[0], @_ >= 2 ? $_[1] : $_[0])
		836	}
		837
161	=back	838	=back
162		839
		840	=head2 OTHER STUFF
		841
		842	Anything that didn't fit any of the other categories, even after applying
		843	force and closing our eyes.
		844
		845	=over 4
		846
		847	=item keep { ... }
		848
		849	This operator takes a code block as argument, that is, one or more
		850	statements enclosed by braces.
		851
		852	The trick is that this code block is only evaluated when the outcome
		853	changes - on other calls the C<keep> simply returns the image it computed
		854	previously (yes, it should only be used with images). Or in other words,
		855	C<keep> I<caches> the result of the code block so it doesn't need to be
		856	computed again.
		857
		858	This can be extremely useful to avoid redoing slow operations - for
		859	example, if your background expression takes the root background, blurs it
		860	and then root-aligns it it would have to blur the root background on every
		861	window move or resize.
		862
		863	Another example is C<load>, which can be quite slow.
		864
		865	In fact, urxvt itself encloses the whole expression in some kind of
		866	C<keep> block so it only is reevaluated as required.
		867
		868	Putting the blur into a C<keep> block will make sure the blur is only done
		869	once, while the C<rootalign> is still done each time the window moves.
		870
		871	rootlign keep { blur 10, root }
		872
		873	This leaves the question of how to force reevaluation of the block,
		874	in case the root background changes: If expression inside the block
		875	is sensitive to some event (root background changes, window geometry
		876	changes), then it will be reevaluated automatically as needed.
		877
		878	=cut
		879
		880	sub keep(&) {
		881	my $id = $_[0]+0;
		882
		883	local $frame = $self->{frame_cache}{$id} \|\|= [$frame];
		884
		885	unless ($frame->[FR_CACHE]) {
		886	$frame->[FR_CACHE] = [ $_[0]() ];
		887
		888	my $self = $self;
		889	my $frame = $frame;
		890	Scalar::Util::weaken $frame;
		891	$self->compile_frame ($frame, sub {
		892	# clear this frame cache, also for all parents
		893	for (my $frame = $frame; $frame; $frame = $frame->[0]) {
		894	undef $frame->[FR_CACHE];
		895	}
		896
		897	$self->recalculate;
		898	});
		899	};
		900
		901	# in scalar context we always return the first original result, which
		902	# is not quite how perl works.
		903	wantarray
		904	? @{ $frame->[FR_CACHE] }
		905	: $frame->[FR_CACHE][0]
		906	}
		907
		908	# sub keep_clear() {
		909	# delete $self->{frame_cache};
		910	# }
		911
		912	=back
		913
163	=cut	914	=cut
164		915
165	}	916	}
166		917
167	sub parse_expr {	918	sub parse_expr {
168	my $expr = eval "sub {\npackage urxvt::bgdsl;\n#line 0 'background expression'\n$_[0]\n}";	919	my $expr = eval
		920	"sub {\n"
		921	. "package urxvt::bgdsl;\n"
		922	. "#line 0 'background expression'\n"
		923	. "$_[0]\n"
		924	. "}";
169	die if $@;	925	die if $@;
170	$expr	926	$expr
171	}	927	}
172		928
173	# compiles a parsed expression	929	# compiles a parsed expression
174	sub set_expr {	930	sub set_expr {
175	my ($self, $expr) = @_;	931	my ($self, $expr) = @_;
176		932
		933	$self->{root} = [];
177	$self->{expr} = $expr;	934	$self->{expr} = $expr;
178	$self->recalculate;	935	$self->recalculate;
179	}	936	}
180		937
		938	# takes a hash of sensitivity indicators and installs watchers
		939	sub compile_frame {
		940	my ($self, $frame, $cb) = @_;
		941
		942	my $state = $frame->[urxvt::bgdsl::FR_STATE] \|\|= {};
		943	my $again = $frame->[urxvt::bgdsl::FR_AGAIN];
		944
		945	# don't keep stuff alive
		946	Scalar::Util::weaken $state;
		947
		948	if ($again->{nested}) {
		949	$state->{nested} = 1;
		950	} else {
		951	delete $state->{nested};
		952	}
		953
		954	if (my $interval = $again->{time}) {
		955	$state->{time} = [$interval, urxvt::timer->new->after ($interval)->interval ($interval)]
		956	if $state->{time}[0] != $interval;
		957
		958	# callback might have changed, although we could just rule that out
		959	$state->{time}[1]->cb (sub {
		960	++$state->{counter};
		961	$cb->();
		962	});
		963	} else {
		964	delete $state->{time};
		965	}
		966
		967	if ($again->{position}) {
		968	$state->{position} = $self->on (position_change => $cb);
		969	} else {
		970	delete $state->{position};
		971	}
		972
		973	if ($again->{size}) {
		974	$state->{size} = $self->on (size_change => $cb);
		975	} else {
		976	delete $state->{size};
		977	}
		978
		979	if ($again->{rootpmap}) {
		980	$state->{rootpmap} = $self->on (rootpmap_change => $cb);
		981	} else {
		982	delete $state->{rootpmap};
		983	}
		984	}
		985
181	# evaluate the current bg expression	986	# evaluate the current bg expression
182	sub recalculate {	987	sub recalculate {
183	my ($self) = @_;	988	my ($arg_self) = @_;
184		989
185	# rate limit evaluation	990	# rate limit evaluation
186		991
187	if ($self->{next_refresh} > urxvt::NOW) {	992	if ($arg_self->{next_refresh} > urxvt::NOW) {
188	$self->{next_refresh_timer} = urxvt::timer->new->after ($self->{next_refresh} - urxvt::NOW)->cb (sub {	993	$arg_self->{next_refresh_timer} = urxvt::timer->new->after ($arg_self->{next_refresh} - urxvt::NOW)->cb (sub {
189	$self->recalculate;	994	$arg_self->recalculate;
190	});	995	});
191	return;	996	return;
192	}	997	}
193		998
194	$self->{next_refresh} = urxvt::NOW + $MIN_INTERVAL;	999	$arg_self->{next_refresh} = urxvt::NOW + $MIN_INTERVAL;
195		1000
196	# set environment to evaluate user expression	1001	# set environment to evaluate user expression
197		1002
198	local $bgdsl_self = $self;	1003	local $self = $arg_self;
		1004	local $HOME = $ENV{HOME};
		1005	local $frame = [];
199		1006
200	local $old = $self->{state};	1007	($x, $y, $w, $h) = $self->background_geometry ($self->{border});
201	local $new = my $state = $self->{state} = {};
202
203	($l, $t, $w, $h) =
204	$self->get_geometry;
205
206	warn "$l,$t,$w,$h\n";#d#
207		1008
208	# evaluate user expression	1009	# evaluate user expression
209		1010
210	my $img = eval { $self->{expr}->() };	1011	my @img = eval { $self->{expr}->() };
211	warn $@ if $@;#d#	1012	die $@ if $@;
		1013	die "background-expr did not return anything.\n" unless @img;
		1014	die "background-expr: expected image(s), got something else.\n"
212	die if !UNIVERSAL::isa $img, "urxvt::img";	1015	if grep { !UNIVERSAL::isa $_, "urxvt::img" } @img;
		1016
		1017	my $img = urxvt::bgdsl::merge @img;
		1018
		1019	$frame->[FR_AGAIN]{size} = 1
		1020	if $img->repeat_mode != urxvt::RepeatNormal;
213		1021
214	# if the expression is sensitive to external events, prepare reevaluation then	1022	# if the expression is sensitive to external events, prepare reevaluation then
215		1023	$self->compile_frame ($frame, sub { $arg_self->recalculate });
216	my $repeat;
217
218	if (my $again = $state->{again}) {
219	$repeat = 1;
220	$state->{timer} = $again == $old->{again}
221	? $old->{timer}
222	: urxvt::timer->new->after ($again)->interval ($again)->cb (sub {
223	++$self->{counter};
224	$self->recalculate
225	});
226	}
227
228	if (delete $state->{position_sensitive}) {
229	$repeat = 1;
230	$self->enable (position_change => sub { $_[0]->recalculate });
231	} else {
232	$self->disable ("position_change");
233	}
234
235	if (delete $state->{size_sensitive}) {
236	$repeat = 1;
237	$self->enable (size_change => sub { $_[0]->recalculate });
238	} else {
239	$self->disable ("size_change");
240	}
241
242	if (delete $state->{rootpmap_sensitive}) {
243	$repeat = 1;
244	$self->enable (rootpmap_change => sub { $_[0]->recalculate });
245	} else {
246	$self->disable ("rootpmap_change");
247	}
248		1024
249	# clear stuff we no longer need	1025	# clear stuff we no longer need
250		1026
251	%$old = ();	1027	# unless (%{ $frame->[FR_STATE] }) {
252
253	unless ($repeat) {
254	delete $self->{state};	1028	# delete $self->{state};
255	delete $self->{expr};	1029	# delete $self->{expr};
256	}	1030	# }
257		1031
258	# prepare and set background pixmap	1032	# set background pixmap
259		1033
260	$img = $img->sub_rect (0, 0, $w, $h)
261	if $img->w != $w \|\| $img->h != $h;
262
263	$self->set_background ($img);	1034	$self->set_background ($img, $self->{border});
264	$self->scr_recolour (0);	1035	$self->scr_recolour (0);
265	$self->want_refresh;	1036	$self->want_refresh;
266	}	1037	}
267		1038
268	sub on_start {	1039	sub on_start {
269	my ($self) = @_;	1040	my ($self) = @_;
270		1041
		1042	my $expr = $self->x_resource ("%.expr")
		1043	or return;
		1044
		1045	$self->has_render
		1046	or die "background extension needs RENDER extension 0.10 or higher, ignoring background-expr.\n";
		1047
271	$self->set_expr (parse_expr $EXPR);	1048	$self->set_expr (parse_expr $expr);
		1049	$self->{border} = $self->x_resource_boolean ("%.border");
		1050
		1051	$MIN_INTERVAL = $self->x_resource ("%.interval");
272		1052
273	()	1053	()
274	}	1054	}
275		1055

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Comparing rxvt-unicode/src/perl/background (file contents): Revision 1.23 by root, Thu Jun 7 10:22:55 2012 UTC vs. Revision 1.69 by root, Mon Jul 2 01:32:26 2012 UTC

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Comparing rxvt-unicode/src/perl/background (file contents):
Revision 1.23 by root, Thu Jun 7 10:22:55 2012 UTC vs.
Revision 1.69 by root, Mon Jul 2 01:32:26 2012 UTC