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

Comparing rxvt-unicode/src/perl/background (file contents):
Revision 1.34 by root, Thu Jun 7 17:04:33 2012 UTC vs.
Revision 1.56 by root, Thu Jun 14 17:06:57 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:%.border.:boolean:respect the terminal border	4	#:META:X_RESOURCE:%.border:boolean:respect the terminal border
		5	#:META:X_RESOURCE:%.interval:seconds:minimum time between updates
5		6
		7	=head1 NAME
		8
6	=head1 background - manage terminal background	9	background - manage terminal background
7		10
8	=head2 SYNOPSIS	11	=head1 SYNOPSIS
9		12
10	rxvt -background-expr 'background expression'	13	urxvt --background-expr 'background expression'
11	-background-border	14	--background-border
		15	--background-interval seconds
12		16
13	=head2 DESCRIPTION	17	=head1 DESCRIPTION
14		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
15	=head2 REFERENCE	176	=head1 REFERENCE
16		177
17	=cut	178	=head2 COMMAND LINE SWITCHES
18		179
19	our $EXPR;	180	=over 4
20	#$EXPR = 'move W * 0.1, -H * 0.1, resize W * 0.5, H * 0.5, repeat_none load "opensource.png"';
21	$EXPR = 'move -TX, -TY, load "argb.png"';
22	#$EXPR = '
23	# rotate W, H, 50, 50, counter 1/59.95, repeat_mirror,
24	# clip X, Y, W, H, repeat_mirror,
25	# load "/root/pix/das_fette_schwein.jpg"
26	#';
27	#$EXPR = 'solid "red"';
28	#$EXPR = 'blur root, 10, 10'
29	#$EXPR = 'blur move (root, -x, -y), 5, 5'
30	#resize load "/root/pix/das_fette_schwein.jpg", w, h
31		181
		182	=item --background-expr perl-expression
		183
		184	Specifies the Perl expression to evaluate.
		185
		186	=item --background-border
		187
		188	By default, the expression creates an image that fills the full window,
		189	overwriting borders and any other areas, such as the scrollbar.
		190
		191	Specifying this flag changes the behaviour, so that the image only
		192	replaces the background of the character area.
		193
		194	=item --background-interval seconds
		195
		196	Since some operations in the underlying XRender extension can effectively
		197	freeze your X-server for prolonged time, this extension enforces a minimum
		198	time between updates, which is normally about 0.1 seconds.
		199
		200	If you want to do updates more often, you can decrease this safety
		201	interval with this switch.
		202
		203	=back
		204
		205	=cut
		206
		207	our %_IMG_CACHE;
		208	our $HOME;
32	our ($self, $old, $new);	209	our ($self, $old, $new);
33	our ($x, $y, $w, $h);	210	our ($x, $y, $w, $h);
34		211
35	# enforce at least this interval between updates	212	# enforce at least this interval between updates
36	our $MIN_INTERVAL = 1/100;	213	our $MIN_INTERVAL = 6/59.951;
37		214
38	{	215	{
39	package urxvt::bgdsl; # background language	216	package urxvt::bgdsl; # background language
		217
		218	use List::Util qw(min max sum shuffle);
40		219
41	=head2 PROVIDERS/GENERATORS	220	=head2 PROVIDERS/GENERATORS
42		221
43	These functions provide an image, by loading it from disk, grabbing it	222	These functions provide an image, by loading it from disk, grabbing it
44	from the root screen or by simply generating it. They are used as starting	223	from the root screen or by simply generating it. They are used as starting
49	=item load $path	228	=item load $path
50		229
51	Loads the image at the given C<$path>. The image is set to plane tiling	230	Loads the image at the given C<$path>. The image is set to plane tiling
52	mode.	231	mode.
53		232
54	Loaded images will be cached for one cycle.	233	Loaded images will be cached for one cycle, and shared between temrinals
		234	running in the same process (e.g. in C<urxvtd>).
55		235
		236	=item load_uc $path
		237
		238	Load uncached - same as load, but does not cache the image. This function
		239	is most useufl if you want to optimise a background expression in some
		240	way.
		241
56	=cut	242	=cut
		243
		244	sub load_uc($) {
		245	my ($path) = @_;
		246
		247	$_IMG_CACHE{$path} \|\| do {
		248	my $img = $self->new_img_from_file ($path);
		249	Scalar::Util::weaken ($_IMG_CACHE{$path} = $img);
		250	$img
		251	}
		252	}
57		253
58	sub load($) {	254	sub load($) {
59	my ($path) = @_;	255	my ($path) = @_;
60		256
61	$new->{load}{$path} = $old->{load}{$path} \|\| $self->new_img_from_file ($path);	257	$new->{load}{$path} = $old->{load}{$path} \|\| load_uc $path;
62	}	258	}
63		259
64	=item root	260	=item root
65		261
66	Returns the root window pixmap, that is, hopefully, the background image	262	Returns the root window pixmap, that is, hopefully, the background image
…		…
70	reevaluated when the bg image changes.	266	reevaluated when the bg image changes.
71		267
72	=cut	268	=cut
73		269
74	sub root() {	270	sub root() {
75	$new->{rootpmap_sensitive} = 1;	271	$new->{again}{rootpmap} = 1;
76	die "root op not supported, exg, we need you";	272	$self->new_img_from_root
77	}	273	}
78		274
79	=item solid $colour	275	=item solid $colour
80		276
81	=item solid $width, $height, $colour	277	=item solid $width, $height, $colour
82		278
83	Creates a new image and completely fills it with the given colour. The	279	Creates a new image and completely fills it with the given colour. The
84	image is set to tiling mode.	280	image is set to tiling mode.
85		281
86	If <$width> and C<$height> are omitted, it creates a 1x1 image, which is	282	If C<$width> and C<$height> are omitted, it creates a 1x1 image, which is
87	useful for solid backgrounds or for use in filtering effects.	283	useful for solid backgrounds or for use in filtering effects.
88		284
89	=cut	285	=cut
90		286
91	sub solid($$;$) {	287	sub solid($;$$) {
92	my $colour = pop;	288	my $colour = pop;
93		289
94	my $img = $self->new_img (urxvt::PictStandardARGB32, $_[0] \|\| 1, $_[1] \|\| 1);	290	my $img = $self->new_img (urxvt::PictStandardARGB32, $_[0] \|\| 1, $_[1] \|\| 1);
95	$img->fill ($colour);	291	$img->fill ($colour);
96	$img	292	$img
97	}	293	}
98		294
99	=back	295	=item clone $img
100		296
101	=head2 VARIABLES	297	Returns an exact copy of the image. This is useful if you want to have
		298	multiple copies of the same image to apply different effects to.
102		299
103	The following functions provide variable data such as the terminal
104	window dimensions. Most of them make your expression sensitive to some
105	events, for example using C<TW> (terminal width) means your expression is
106	evaluated again when the terminal is resized.
107
108	=over 4
109
110	=item TX
111
112	=item TY
113
114	Return the X and Y coordinates of the terminal window (the terminal
115	window is the full window by default, and the character area only when in
116	border-respect mode).
117
118	Using these functions make your expression sensitive to window moves.
119
120	These functions are mainly useful to align images to the root window.
121
122	Example: load an image and align it so it looks as if anchored to the
123	background.
124
125	move -TX, -TY, load "mybg.png"
126
127	=item TW
128
129	Return the width (C<TW>) and height (C<TH>) of the terminal window (the
130	terminal window is the full window by default, and the character area only
131	when in border-respect mode).
132
133	Using these functions make your expression sensitive to window resizes.
134
135	These functions are mainly useful to scale images, or to clip images to
136	the window size to conserve memory.
137
138	Example: take the screen background, clip it to the window size, blur it a
139	bit, align it to the window position and use it as background.
140
141	clip move -TX, -TY, blur 5, root
142
143	=cut	300	=cut
144		301
145	sub TX() { $new->{position_sensitive} = 1; $x }
146	sub TY() { $new->{position_sensitive} = 1; $y }
147	sub TW() { $new->{size_sensitive} = 1; $w }
148	sub TH() { $new->{size_sensitive} = 1; $h }
149
150	=item now
151
152	Returns the current time as (fractional) seconds since the epoch.
153
154	Using this expression does I<not> make your expression sensitive to time,
155	but the next two functions do.
156
157	=item again $seconds
158
159	When this function is used the expression will be reevaluated again in
160	C<$seconds> seconds.
161
162	Example: load some image and rotate it according to the time of day (as if it were
163	the hour pointer of a clock). update this image every minute.
164
165	again 60; rotate TW, TH, 50, 50, (now % 86400) * -720 / 86400, scale load "myclock.png"
166
167	=item counter $seconds
168
169	Like C<again>, but also returns an increasing counter value, starting at
170	0, which might be useful for some simple animation effects.
171
172	=cut
173
174	sub now() { urxvt::NOW }
175
176	sub again($) {
177	$new->{again} = $_[0];
178	}
179
180	sub counter($) {	302	sub clone($) {
181	$new->{again} = $_[0];	303	$_[0]->clone
182	$self->{counter} + 0
183	}	304	}
184		305
185	=back	306	=item merge $img ...
		307
		308	Takes any number of images and merges them together, creating a single image containing them all.
		309
		310	=cut
		311
		312	sub merge(@) {
		313	#TODO
		314	}
186		315
187	=head2 TILING MODES	316	=head2 TILING MODES
188		317
189	The following operators modify the tiling mode of an image, that is, the	318	The following operators modify the tiling mode of an image, that is, the
190	way that pixels outside the image area are painted when the image is used.	319	way that pixels outside the image area are painted when the image is used.
…		…
207	Similar to tile, but reflects the image each time it uses a new copy, so	336	Similar to tile, but reflects the image each time it uses a new copy, so
208	that top edges always touch top edges, right edges always touch right	337	that top edges always touch top edges, right edges always touch right
209	edges and so on (with normal tiling, left edges always touch right edges	338	edges and so on (with normal tiling, left edges always touch right edges
210	and top always touch bottom edges).	339	and top always touch bottom edges).
211		340
212	Exmaple: load an image and mirror it over the background, avoiding sharp	341	Example: load an image and mirror it over the background, avoiding sharp
213	edges at the image borders at the expense of mirroring the image itself	342	edges at the image borders at the expense of mirroring the image itself
214		343
215	mirror load "mybg.png"	344	mirror load "mybg.png"
216		345
217	=item pad $img	346	=item pad $img
…		…
219	Takes an image and modifies it so that all pixels outside the image area	348	Takes an image and modifies it so that all pixels outside the image area
220	become transparent. This mode is most useful when you want to place an	349	become transparent. This mode is most useful when you want to place an
221	image over another image or the background colour while leaving all	350	image over another image or the background colour while leaving all
222	background pixels outside the image unchanged.	351	background pixels outside the image unchanged.
223		352
224	Example: load an image and display it in the upper left corner. The rets	353	Example: load an image and display it in the upper left corner. The rest
225	of the space is left "empty" (transparent or wahtever your compisotr does	354	of the space is left "empty" (transparent or whatever your compositor does
226	in alpha mode, else background colour).	355	in alpha mode, else background colour).
227		356
228	pad load "mybg.png"	357	pad load "mybg.png"
229		358
230	=item extend $img	359	=item extend $img
231		360
232	Extends the image over the whole plane, using the closest pixel in the	361	Extends the image over the whole plane, using the closest pixel in the
233	area outside the image. This mode is mostly useful when you more complex	362	area outside the image. This mode is mostly useful when you use more complex
234	filtering operations and want the pixels outside the image to have the	363	filtering operations and want the pixels outside the image to have the
235	same values as the pixels near the edge.	364	same values as the pixels near the edge.
236		365
237	Example: just for curiosity, how does this pixel extension stuff work?	366	Example: just for curiosity, how does this pixel extension stuff work?
238		367
…		…
264	$img	393	$img
265	}	394	}
266		395
267	=back	396	=back
268		397
269	=head2 PIXEL OPERATORS	398	=head2 VARIABLE VALUES
270		399
271	The following operators modify the image pixels in various ways.	400	The following functions provide variable data such as the terminal window
		401	dimensions. They are not (Perl-) variables, they just return stuff that
		402	varies. Most of them make your expression sensitive to some events, for
		403	example using C<TW> (terminal width) means your expression is evaluated
		404	again when the terminal is resized.
272		405
273	=over 4	406	=over 4
274		407
275	=item clone $img	408	=item TX
276		409
277	Returns an exact copy of the image.	410	=item TY
278		411
279	=cut	412	Return the X and Y coordinates of the terminal window (the terminal
		413	window is the full window by default, and the character area only when in
		414	border-respect mode).
280		415
		416	Using these functions make your expression sensitive to window moves.
		417
		418	These functions are mainly useful to align images to the root window.
		419
		420	Example: load an image and align it so it looks as if anchored to the
		421	background.
		422
		423	move -TX, -TY, load "mybg.png"
		424
		425	=item TW
		426
		427	Return the width (C<TW>) and height (C<TH>) of the terminal window (the
		428	terminal window is the full window by default, and the character area only
		429	when in border-respect mode).
		430
		431	Using these functions make your expression sensitive to window resizes.
		432
		433	These functions are mainly useful to scale images, or to clip images to
		434	the window size to conserve memory.
		435
		436	Example: take the screen background, clip it to the window size, blur it a
		437	bit, align it to the window position and use it as background.
		438
		439	clip move -TX, -TY, once { blur 5, root }
		440
		441	=cut
		442
		443	sub TX() { $new->{again}{position} = 1; $x }
		444	sub TY() { $new->{again}{position} = 1; $y }
		445	sub TW() { $new->{again}{size} = 1; $w }
		446	sub TH() { $new->{again}{size} = 1; $h }
		447
		448	=item now
		449
		450	Returns the current time as (fractional) seconds since the epoch.
		451
		452	Using this expression does I<not> make your expression sensitive to time,
		453	but the next two functions do.
		454
		455	=item again $seconds
		456
		457	When this function is used the expression will be reevaluated again in
		458	C<$seconds> seconds.
		459
		460	Example: load some image and rotate it according to the time of day (as if it were
		461	the hour pointer of a clock). Update this image every minute.
		462
		463	again 60; rotate 50, 50, (now % 86400) * -720 / 86400, scale load "myclock.png"
		464
		465	=item counter $seconds
		466
		467	Like C<again>, but also returns an increasing counter value, starting at
		468	0, which might be useful for some simple animation effects.
		469
		470	=cut
		471
		472	sub now() { urxvt::NOW }
		473
		474	sub again($) {
		475	$new->{again}{time} = $_[0];
		476	}
		477
281	sub clone($) {	478	sub counter($) {
282	$_[0]->clone	479	$new->{again}{time} = $_[0];
		480	$self->{counter} + 0
283	}	481	}
		482
		483	=back
		484
		485	=head2 SHAPE CHANGING OPERATORS
		486
		487	The following operators modify the shape, size or position of the image.
		488
		489	=over 4
284		490
285	=item clip $img	491	=item clip $img
286		492
287	=item clip $width, $height, $img	493	=item clip $width, $height, $img
288		494
…		…
312	$img->sub_rect ($_[0], $_[1], $w, $h)	518	$img->sub_rect ($_[0], $_[1], $w, $h)
313	}	519	}
314		520
315	=item scale $img	521	=item scale $img
316		522
317	=item scale $size_percent, $img	523	=item scale $size_factor, $img
318		524
319	=item scale $width_percent, $height_percent, $img	525	=item scale $width_factor, $height_factor, $img
320		526
321	Scales the image by the given percentages in horizontal	527	Scales the image by the given factors in horizontal
322	(C<$width_percent>) and vertical (C<$height_percent>) direction.	528	(C<$width>) and vertical (C<$height>) direction.
323		529
324	If only one percentage is give, it is used for both directions.	530	If only one factor is give, it is used for both directions.
325		531
326	If no percentages are given, scales the image to the window size without	532	If no factors are given, scales the image to the window size without
327	keeping aspect.	533	keeping aspect.
328		534
329	=item resize $width, $height, $img	535	=item resize $width, $height, $img
330		536
331	Resizes the image to exactly C<$width> times C<$height> pixels.	537	Resizes the image to exactly C<$width> times C<$height> pixels.
332		538
333	=cut	539	=item fit $img
334		540
335	#TODO: maximise, maximise_fill?	541	=item fit $width, $height, $img
		542
		543	Fits the image into the given C<$width> and C<$height> without changing
		544	aspect, or the terminal size. That means it will be shrunk or grown until
		545	the whole image fits into the given area, possibly leaving borders.
		546
		547	=item cover $img
		548
		549	=item cover $width, $height, $img
		550
		551	Similar to C<fit>, but shrinks or grows until all of the area is covered
		552	by the image, so instead of potentially leaving borders, it will cut off
		553	image data that doesn't fit.
		554
		555	=cut
336		556
337	sub scale($;$;$) {	557	sub scale($;$;$) {
338	my $img = pop;	558	my $img = pop;
339		559
340	@_ == 2 ? $img->scale ($_[0] * $img->w * 0.01, $_[1] * $img->h * 0.01)	560	@_ == 2 ? $img->scale ($_[0] * $img->w, $_[1] * $img->h)
341	: @_ ? $img->scale ($_[0] * $img->w * 0.01, $_[0] * $img->h * 0.01)	561	: @_ ? $img->scale ($_[0] * $img->w, $_[0] * $img->h)
342	: $img->scale (TW, TH)	562	: $img->scale (TW, TH)
343	}	563	}
344		564
345	sub resize($$$) {	565	sub resize($$$) {
346	my $img = pop;	566	my $img = pop;
347	$img->scale ($_[0], $_[1])	567	$img->scale ($_[0], $_[1])
348	}	568	}
		569
		570	sub fit($;$$) {
		571	my $img = pop;
		572	my $w = ($_[0] \|\| TW) / $img->w;
		573	my $h = ($_[1] \|\| TH) / $img->h;
		574	scale +(min $w, $h), $img
		575	}
		576
		577	sub cover($;$$) {
		578	my $img = pop;
		579	my $w = ($_[0] \|\| TW) / $img->w;
		580	my $h = ($_[1] \|\| TH) / $img->h;
		581	scale +(max $w, $h), $img
		582	}
		583
		584	=item move $dx, $dy, $img
		585
		586	Moves the image by C<$dx> pixels in the horizontal, and C<$dy> pixels in
		587	the vertical.
		588
		589	Example: move the image right by 20 pixels and down by 30.
		590
		591	move 20, 30, ...
		592
		593	=item align $xalign, $yalign, $img
		594
		595	Aligns the image according to a factor - C<0> means the image is moved to
		596	the left or top edge (for C<$xalign> or C<$yalign>), C<0.5> means it is
		597	exactly centered and C<1> means it touches the right or bottom edge.
		598
		599	Example: remove any visible border around an image, center it vertically but move
		600	it to the right hand side.
		601
		602	align 1, 0.5, pad $img
		603
		604	=item center $img
		605
		606	=item center $width, $height, $img
		607
		608	Centers the image, i.e. the center of the image is moved to the center of
		609	the terminal window (or the box specified by C<$width> and C<$height> if
		610	given).
		611
		612	Example: load an image and center it.
		613
		614	center pad load "mybg.png"
		615
		616	=item rootalign $img
		617
		618	Moves the image so that it appears glued to the screen as opposed to the
		619	window. This gives the illusion of a larger area behind the window. It is
		620	exactly equivalent to C<move -TX, -TY>, that is, it moves the image to the
		621	top left of the screen.
		622
		623	Example: load a background image, put it in mirror mode and root align it.
		624
		625	rootalign mirror load "mybg.png"
		626
		627	Example: take the screen background and align it, giving the illusion of
		628	transparency as long as the window isn't in front of other windows.
		629
		630	rootalign root
		631
		632	=cut
349		633
350	sub move($$;$) {	634	sub move($$;$) {
351	my $img = pop->clone;	635	my $img = pop->clone;
352	$img->move ($_[0], $_[1]);	636	$img->move ($_[0], $_[1]);
353	$img	637	$img
354	}	638	}
355		639
		640	sub align($;$$) {
		641	my $img = pop;
		642
		643	move $_[0] * (TW - $img->w),
		644	$_[1] * (TH - $img->h),
		645	$img
		646	}
		647
		648	sub center($;$$) {
		649	my $img = pop;
		650	my $w = $_[0] \|\| TW;
		651	my $h = $_[1] \|\| TH;
		652
		653	move 0.5 * ($w - $img->w), 0.5 * ($h - $img->h), $img
		654	}
		655
		656	sub rootalign($) {
		657	move -TX, -TY, $_[0]
		658	}
		659
		660	=item rotate $center_x, $center_y, $degrees
		661
		662	Rotates the image by C<$degrees> degrees, counter-clockwise, around the
		663	pointer at C<$center_x> and C<$center_y> (specified as factor of image
		664	width/height).
		665
		666	#TODO# new width, height, maybe more operators?
		667
		668	Example: rotate the image by 90 degrees
		669
		670	=cut
		671
356	sub rotate($$$$$$) {	672	sub rotate($$$$) {
357	my $img = pop;	673	my $img = pop;
358	$img->rotate (	674	$img->rotate (
359	$_[0],
360	$_[1],
361	$_[2] * $img->w * .01,	675	$_[0] * $img->w,
362	$_[3] * $img->h * .01,	676	$_[1] * $img->h,
363	$_[4] * (3.14159265 / 180),	677	$_[2] * (3.14159265 / 180),
364	)	678	)
365	}	679	}
366		680
367	sub blur($$;$) {	681	=back
368	my $img = pop;	682
369	$img->blur ($_[0], @_ >= 2 ? $_[1] : $_[0])	683	=head2 COLOUR MODIFICATIONS
370	}	684
		685	The following operators change the pixels of the image.
		686
		687	=over 4
		688
		689	=item contrast $factor, $img
		690
		691	=item contrast $r, $g, $b, $img
		692
		693	=item contrast $r, $g, $b, $a, $img
		694
		695	Adjusts the I<contrast> of an image.
		696
		697	The first form applies a single C<$factor> to red, green and blue, the
		698	second form applies separate factors to each colour channel, and the last
		699	form includes the alpha channel.
		700
		701	Values from 0 to 1 lower the contrast, values higher than 1 increase the
		702	contrast.
		703
		704	Due to limitations in the underlying XRender extension, lowering contrast
		705	also reduces brightness, while increasing contrast currently also
		706	increases brightness.
		707
		708	=item brightness $bias, $img
		709
		710	=item brightness $r, $g, $b, $img
		711
		712	=item brightness $r, $g, $b, $a, $img
		713
		714	Adjusts the brightness of an image.
		715
		716	The first form applies a single C<$bias> to red, green and blue, the
		717	second form applies separate biases to each colour channel, and the last
		718	form includes the alpha channel.
		719
		720	Values less than 0 reduce brightness, while values larger than 0 increase
		721	it. Useful range is from -1 to 1 - the former results in a black, the
		722	latter in a white picture.
		723
		724	Due to idiosyncrasies in the underlying XRender extension, biases less
		725	than zero can be I<very> slow.
		726
		727	=cut
371		728
372	sub contrast($$;$$;$) {	729	sub contrast($$;$$;$) {
373	my $img = pop;	730	my $img = pop;
374	my ($r, $g, $b, $a) = @_;	731	my ($r, $g, $b, $a) = @_;
375		732
376	($g, $b) = ($r, $r) if @_ < 4;	733	($g, $b) = ($r, $r) if @_ < 3;
377	$a = 1 if @_ < 5;	734	$a = 1 if @_ < 4;
378		735
379	$img = $img->clone;	736	$img = $img->clone;
380	$img->contrast ($r, $g, $b, $a);	737	$img->contrast ($r, $g, $b, $a);
381	$img	738	$img
382	}	739	}
383		740
384	sub brightness($$;$$;$) {	741	sub brightness($$;$$;$) {
385	my $img = pop;	742	my $img = pop;
386	my ($r, $g, $b, $a) = @_;	743	my ($r, $g, $b, $a) = @_;
387		744
388	($g, $b) = ($r, $r) if @_ < 4;	745	($g, $b) = ($r, $r) if @_ < 3;
389	$a = 1 if @_ < 5;	746	$a = 1 if @_ < 4;
390		747
391	$img = $img->clone;	748	$img = $img->clone;
392	$img->brightness ($r, $g, $b, $a);	749	$img->brightness ($r, $g, $b, $a);
393	$img	750	$img
		751	}
		752
		753	=item blur $radius, $img
		754
		755	=item blur $radius_horz, $radius_vert, $img
		756
		757	Gaussian-blurs the image with (roughly) C<$radius> pixel radius. The radii
		758	can also be specified separately.
		759
		760	Blurring is often I<very> slow, at least compared or other
		761	operators. Larger blur radii are slower than smaller ones, too, so if you
		762	don't want to freeze your screen for long times, start experimenting with
		763	low values for radius (<5).
		764
		765	=cut
		766
		767	sub blur($$;$) {
		768	my $img = pop;
		769	$img->blur ($_[0], @_ >= 2 ? $_[1] : $_[0])
		770	}
		771
		772	=back
		773
		774	=head2 OTHER STUFF
		775
		776	Anything that didn't fit any of the other categories, even after applying
		777	force and closing our eyes.
		778
		779	=over 4
		780
		781	=item once { ... }
		782
		783	This function takes a code block as argument, that is, one or more
		784	statements enclosed by braces.
		785
		786	The trick is that this code block is only evaluated once - future calls
		787	will simply return the original image (yes, it should only be used with
		788	images).
		789
		790	This can be extremely useful to avoid redoign the same slow operations
		791	again and again- for example, if your background expression takes the root
		792	background, blurs it and then root-aligns it it would have to blur the
		793	root background on every window move or resize.
		794
		795	Putting the blur into a C<once> block will make sure the blur is only done
		796	once:
		797
		798	rootlign once { blur 10, root }
		799
		800	This leaves the question of how to force reevaluation of the block, in
		801	case the root background changes: Right now, all once blocks forget that
		802	they ahve been executed before each time the root background changes (if
		803	the expression is sensitive to that) or when C<once_again> is called.
		804
		805	=item once_again
		806
		807	Resets all C<once> block as if they had never been called, i.e. on the
		808	next call they will be reevaluated again.
		809
		810	=cut
		811
		812	sub once(&) {
		813	my $once = $self->{once_cache}{$_[0]+0} \|\|= do {
		814	local $new->{again};
		815	my @res = $_[0]();
		816	[$new->{again}, \@res]
		817	};
		818
		819	$new->{again} = {
		820	%{ $new->{again} },
		821	%{ $once->[0] }
		822	};
		823
		824	# in scalar context we always return the first original result, which
		825	# is not quite how perl works.
		826	wantarray
		827	? @{ $once->[1] }
		828	: $once->[1][0]
		829	}
		830
		831	sub once_again() {
		832	delete $self->{once_cache};
394	}	833	}
395		834
396	=back	835	=back
397		836
398	=cut	837	=cut
…		…
430		869
431	# set environment to evaluate user expression	870	# set environment to evaluate user expression
432		871
433	local $self = $arg_self;	872	local $self = $arg_self;
434		873
		874	local $HOME = $ENV{HOME};
435	local $old = $self->{state};	875	local $old = $self->{state};
436	local $new = my $state = $self->{state} = {};	876	local $new = my $state = $self->{state} = {};
437		877
438	($x, $y, $w, $h) =	878	($x, $y, $w, $h) =
439	$self->background_geometry ($self->{border});	879	$self->background_geometry ($self->{border});
440		880
441	# evaluate user expression	881	# evaluate user expression
442		882
443	my $img = eval { $self->{expr}->() };	883	my $img = eval { $self->{expr}->() };
444	warn $@ if $@;#d#	884	warn $@ if $@;#d#
445	die if !UNIVERSAL::isa $img, "urxvt::img";	885	die "background-expr did not return an image.\n" if !UNIVERSAL::isa $img, "urxvt::img";
446		886
447	$state->{size_sensitive} = 1	887	# if the expression is sensitive to external events, prepare reevaluation then
		888
		889	my $again = delete $state->{again};
		890
		891	$again->{size} = 1
448	if $img->repeat_mode != urxvt::RepeatNormal;	892	if $img->repeat_mode != urxvt::RepeatNormal;
449		893
450	# if the expression is sensitive to external events, prepare reevaluation then
451
452	my $repeat;
453
454	if (my $again = $state->{again}) {	894	if (my $again = $again->{time}) {
455	$repeat = 1;	895	my $self = $self;
456	$state->{timer} = $again == $old->{again}	896	$state->{timer} = $again == $old->{again}
457	? $old->{timer}	897	? $old->{timer}
458	: urxvt::timer->new->after ($again)->interval ($again)->cb (sub {	898	: urxvt::timer->new->after ($again)->interval ($again)->cb (sub {
459	++$self->{counter};	899	++$self->{counter};
460	$self->recalculate	900	$self->recalculate
461	});	901	});
462	}	902	}
463		903
464	if (delete $state->{position_sensitive}) {	904	if ($again->{position}) {
465	$repeat = 1;
466	$self->enable (position_change => sub { $_[0]->recalculate });	905	$self->enable (position_change => sub { $_[0]->recalculate });
467	} else {	906	} else {
468	$self->disable ("position_change");	907	$self->disable ("position_change");
469	}	908	}
470		909
471	if (delete $state->{size_sensitive}) {	910	if ($again->{size}) {
472	$repeat = 1;
473	$self->enable (size_change => sub { $_[0]->recalculate });	911	$self->enable (size_change => sub { $_[0]->recalculate });
474	} else {	912	} else {
475	$self->disable ("size_change");	913	$self->disable ("size_change");
476	}	914	}
477		915
478	if (delete $state->{rootpmap_sensitive}) {	916	if ($again->{rootpmap}) {
479	$repeat = 1;
480	$self->enable (rootpmap_change => sub { $_[0]->recalculate });	917	$self->enable (rootpmap_change => sub {
		918	delete $_[0]{once_cache}; # this will override once-block values from
		919	$_[0]->recalculate;
		920	});
481	} else {	921	} else {
482	$self->disable ("rootpmap_change");	922	$self->disable ("rootpmap_change");
483	}	923	}
484		924
485	# clear stuff we no longer need	925	# clear stuff we no longer need
486		926
487	%$old = ();	927	%$old = ();
488		928
489	unless ($repeat) {	929	unless (%$again) {
490	delete $self->{state};	930	delete $self->{state};
491	delete $self->{expr};	931	delete $self->{expr};
492	}	932	}
493		933
494	# set background pixmap	934	# set background pixmap
…		…
499	}	939	}
500		940
501	sub on_start {	941	sub on_start {
502	my ($self) = @_;	942	my ($self) = @_;
503		943
504	my $expr = $self->x_resource ("background.expr")	944	my $expr = $self->x_resource ("%.expr")
505	or return;	945	or return;
506		946
		947	$self->has_render
		948	or die "background extension needs RENDER extension 0.10 or higher, ignoring background-expr.\n";
		949
507	$self->set_expr (parse_expr $expr);	950	$self->set_expr (parse_expr $expr);
508	$self->{border} = $self->x_resource_boolean ("background.border");	951	$self->{border} = $self->x_resource_boolean ("%.border");
		952
		953	$MIN_INTERVAL = $self->x_resource ("%.interval");
509		954
510	()	955	()
511	}	956	}
512		957

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Comparing rxvt-unicode/src/perl/background (file contents): Revision 1.34 by root, Thu Jun 7 17:04:33 2012 UTC vs. Revision 1.56 by root, Thu Jun 14 17:06:57 2012 UTC

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Comparing rxvt-unicode/src/perl/background (file contents):
Revision 1.34 by root, Thu Jun 7 17:04:33 2012 UTC vs.
Revision 1.56 by root, Thu Jun 14 17:06:57 2012 UTC