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Revision 1.69 by root, Mon Jul 2 01:32:26 2012 UTC vs.
Revision 1.76 by root, Tue Aug 14 23:57:07 2012 UTC

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11=head1 SYNOPSIS 11=head1 SYNOPSIS
12 12
13 urxvt --background-expr 'background expression' 13 urxvt --background-expr 'background expression'
14 --background-border 14 --background-border
15 --background-interval seconds 15 --background-interval seconds
16
17=head1 QUICK AND DIRTY CHEAT SHEET
18
19Just load a random jpeg image and tile the background with it without
20scaling or anything else:
21
22 load "/path/to/img.jpg"
23
24The same, but use mirroring/reflection instead of tiling:
25
26 mirror load "/path/to/img.jpg"
27
28Load an image and scale it to exactly fill the terminal window:
29
30 scale keep { load "/path/to/img.jpg" }
31
32Implement pseudo-transparency by using a suitably-aligned root pixmap
33as window background:
34
35 rootalign root
36
37Likewise, but keep a blurred copy:
38
39 rootalign keep { blur 10, root }
16 40
17=head1 DESCRIPTION 41=head1 DESCRIPTION
18 42
19This extension manages the terminal background by creating a picture that 43This extension manages the terminal background by creating a picture that
20is behind the text, replacing the normal background colour. 44is behind the text, replacing the normal background colour.
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74 return load "$HOME/sunday.png"; 98 return load "$HOME/sunday.png";
75 } 99 }
76 } 100 }
77 101
78This inner expression is evaluated once per hour (and whenever the 102This inner expression is evaluated once per hour (and whenever the
79temrinal window is resized). It sets F<sunday.png> as background on 103terminal window is resized). It sets F<sunday.png> as background on
80Sundays, and F<weekday.png> on all other days. 104Sundays, and F<weekday.png> on all other days.
81 105
82Fortunately, we expect that most expressions will be much simpler, with 106Fortunately, we expect that most expressions will be much simpler, with
83little Perl knowledge needed. 107little Perl knowledge needed.
84 108
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119width and doubles the image height: 143width and doubles the image height:
120 144
121 scale 0.5, 2, load "$HOME/mypic.png" 145 scale 0.5, 2, load "$HOME/mypic.png"
122 146
123IF you try out these expressions, you might suffer from some sluggishness, 147IF you try out these expressions, you might suffer from some sluggishness,
124because each time the terminal is resized, it loads the PNG image agin 148because each time the terminal is resized, it loads the PNG image again
125and scales it. Scaling is usually fast (and unavoidable), but loading the 149and scales it. Scaling is usually fast (and unavoidable), but loading the
126image can be quite time consuming. This is where C<keep> comes in handy: 150image can be quite time consuming. This is where C<keep> comes in handy:
127 151
128 scale 0.5, 2, keep { load "$HOME/mypic.png" } 152 scale 0.5, 2, keep { load "$HOME/mypic.png" }
129 153
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156 180
157This one first takes a snapshot of the screen background image, and then 181This one first takes a snapshot of the screen background image, and then
158moves it to the upper left corner of the screen (as opposed to the upper 182moves it to the upper left corner of the screen (as opposed to the upper
159left corner of the terminal window)- the result is pseudo-transparency: 183left corner of the terminal window)- the result is pseudo-transparency:
160the image seems to be static while the window is moved around. 184the image seems to be static while the window is moved around.
185
186=head2 COLOUR SPECIFICATIONS
187
188Whenever an operator expects a "colour", then this can be specified in one
189of 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
196OR 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
161 201
162=head2 CACHING AND SENSITIVITY 202=head2 CACHING AND SENSITIVITY
163 203
164Since some operations (such as C<load> and C<blur>) can take a long time, 204Since some operations (such as C<load> and C<blur>) can take a long time,
165caching results can be very important for a smooth operation. Caching can 205caching results can be very important for a smooth operation. Caching can
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273uses it), then the in-memory copy us returned instead. 313uses it), then the in-memory copy us returned instead.
274 314
275=item load_uc $path 315=item load_uc $path
276 316
277Load uncached - same as load, but does not cache the image, which means it 317Load uncached - same as load, but does not cache the image, which means it
278is I<always> loaded from the filesystem again. 318is I<always> loaded from the filesystem again, even if another copy of it
319is in memory at the time.
279 320
280=cut 321=cut
322
323 sub load_uc($) {
324 $self->new_img_from_file ($_[0])
325 }
281 326
282 sub load($) { 327 sub load($) {
283 my ($path) = @_; 328 my ($path) = @_;
284 329
285 $_IMG_CACHE{$path} || do { 330 $_IMG_CACHE{$path} || do {
286 my $img = $self->new_img_from_file ($path); 331 my $img = load_uc $path;
287 Scalar::Util::weaken ($_IMG_CACHE{$path} = $img); 332 Scalar::Util::weaken ($_IMG_CACHE{$path} = $img);
288 $img 333 $img
289 } 334 }
290 } 335 }
291 336
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376 $base->draw ($_) 421 $base->draw ($_)
377 for @_; 422 for @_;
378 423
379 $base 424 $base
380 } 425 }
426
427=back
381 428
382=head2 TILING MODES 429=head2 TILING MODES
383 430
384The following operators modify the tiling mode of an image, that is, the 431The following operators modify the tiling mode of an image, that is, the
385way that pixels outside the image area are painted when the image is used. 432way that pixels outside the image area are painted when the image is used.
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750 797
751The following operators change the pixels of the image. 798The following operators change the pixels of the image.
752 799
753=over 4 800=over 4
754 801
802=item tint $color, $img
803
804Tints the image in the given colour.
805
806Example: tint the image red.
807
808 tint "red", load "rgb.png"
809
810Example: the same, but specify the colour by component.
811
812 tint [1, 0, 0], load "rgb.png"
813
814=cut
815
816 sub tint($$) {
817 $_[1]->tint ($_[0])
818 }
819
755=item contrast $factor, $img 820=item contrast $factor, $img
756 821
757=item contrast $r, $g, $b, $img 822=item contrast $r, $g, $b, $img
758 823
759=item contrast $r, $g, $b, $a, $img 824=item contrast $r, $g, $b, $a, $img
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788latter in a white picture. 853latter in a white picture.
789 854
790Due to idiosyncrasies in the underlying XRender extension, biases less 855Due to idiosyncrasies in the underlying XRender extension, biases less
791than zero can be I<very> slow. 856than zero can be I<very> slow.
792 857
858You can also try the experimental(!) C<muladd> operator.
859
793=cut 860=cut
794 861
795 sub contrast($$;$$;$) { 862 sub contrast($$;$$;$) {
796 my $img = pop; 863 my $img = pop;
797 my ($r, $g, $b, $a) = @_; 864 my ($r, $g, $b, $a) = @_;
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812 $a = 1 if @_ < 4; 879 $a = 1 if @_ < 4;
813 880
814 $img = $img->clone; 881 $img = $img->clone;
815 $img->brightness ($r, $g, $b, $a); 882 $img->brightness ($r, $g, $b, $a);
816 $img 883 $img
884 }
885
886=item muladd $mul, $add, $img # EXPERIMENTAL
887
888First multipliesthe pixels by C<$mul>, then adds C<$add>. This cna be used
889to implement brightness and contrast at the same time, with a wider value
890range than contrast and brightness operators.
891
892Due to numerous bugs in XRender implementations, it can also introduce a
893number of visual artifacts.
894
895Example: increase contrast by a factor of C<$c> without changing image
896brightness too much.
897
898 muladd $c, (1 - $c) * 0.5, $img
899
900=cut
901
902 sub muladd($$$) {
903 $_[2]->muladd ($_[0], $_[1])
817 } 904 }
818 905
819=item blur $radius, $img 906=item blur $radius, $img
820 907
821=item blur $radius_horz, $radius_vert, $img 908=item blur $radius_horz, $radius_vert, $img
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866C<keep> block so it only is reevaluated as required. 953C<keep> block so it only is reevaluated as required.
867 954
868Putting the blur into a C<keep> block will make sure the blur is only done 955Putting the blur into a C<keep> block will make sure the blur is only done
869once, while the C<rootalign> is still done each time the window moves. 956once, while the C<rootalign> is still done each time the window moves.
870 957
871 rootlign keep { blur 10, root } 958 rootalign keep { blur 10, root }
872 959
873This leaves the question of how to force reevaluation of the block, 960This leaves the question of how to force reevaluation of the block,
874in case the root background changes: If expression inside the block 961in case the root background changes: If expression inside the block
875is sensitive to some event (root background changes, window geometry 962is sensitive to some event (root background changes, window geometry
876changes), then it will be reevaluated automatically as needed. 963changes), then it will be reevaluated automatically as needed.
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928 1015
929# compiles a parsed expression 1016# compiles a parsed expression
930sub set_expr { 1017sub set_expr {
931 my ($self, $expr) = @_; 1018 my ($self, $expr) = @_;
932 1019
933 $self->{root} = []; 1020 $self->{root} = []; # the outermost frame
934 $self->{expr} = $expr; 1021 $self->{expr} = $expr;
935 $self->recalculate; 1022 $self->recalculate;
936} 1023}
937 1024
938# takes a hash of sensitivity indicators and installs watchers 1025# takes a hash of sensitivity indicators and installs watchers
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1000 1087
1001 # set environment to evaluate user expression 1088 # set environment to evaluate user expression
1002 1089
1003 local $self = $arg_self; 1090 local $self = $arg_self;
1004 local $HOME = $ENV{HOME}; 1091 local $HOME = $ENV{HOME};
1005 local $frame = []; 1092 local $frame = $self->{root};
1006 1093
1007 ($x, $y, $w, $h) = $self->background_geometry ($self->{border}); 1094 ($x, $y, $w, $h) = $self->background_geometry ($self->{border});
1008 1095
1009 # evaluate user expression 1096 # evaluate user expression
1010 1097

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