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Revision 1.68 by root, Sun Jul 1 21:47:07 2012 UTC vs.
Revision 1.77 by root, Tue Sep 4 11:21:11 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 $path
276 316
277Load uncached - same as load, but does not cache the image, which means it 317Load uncached - same as load, but does not cache the image, which means it
278is I<always> loaded from the filesystem again. 318is I<always> loaded from the filesystem again, even if another copy of it
319is in memory at the time.
279 320
280=cut 321=cut
281 322
282 sub load_uc($) { 323 sub load_uc($) {
283 $self->new_img_from_file ($path) 324 $self->new_img_from_file ($_[0])
284 } 325 }
285 326
286 sub load($) { 327 sub load($) {
287 my ($path) = @_; 328 my ($path) = @_;
288 329
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381 for @_; 422 for @_;
382 423
383 $base 424 $base
384 } 425 }
385 426
427=back
428
386=head2 TILING MODES 429=head2 TILING MODES
387 430
388The 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
389way 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.
390 433
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491background (that's exactly what C<rootalign> does btw.): 534background (that's exactly what C<rootalign> does btw.):
492 535
493 move -TX, -TY, keep { load "mybg.png" } 536 move -TX, -TY, keep { load "mybg.png" }
494 537
495=item TW 538=item TW
539
540=item TH
496 541
497Return the width (C<TW>) and height (C<TH>) of the terminal window (the 542Return the width (C<TW>) and height (C<TH>) of the terminal window (the
498terminal window is the full window by default, and the character area only 543terminal window is the full window by default, and the character area only
499when in border-respect mode). 544when in border-respect mode).
500 545
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754 799
755The following operators change the pixels of the image. 800The following operators change the pixels of the image.
756 801
757=over 4 802=over 4
758 803
804=item tint $color, $img
805
806Tints the image in the given colour.
807
808Example: tint the image red.
809
810 tint "red", load "rgb.png"
811
812Example: the same, but specify the colour by component.
813
814 tint [1, 0, 0], load "rgb.png"
815
816=cut
817
818 sub tint($$) {
819 $_[1]->tint ($_[0])
820 }
821
759=item contrast $factor, $img 822=item contrast $factor, $img
760 823
761=item contrast $r, $g, $b, $img 824=item contrast $r, $g, $b, $img
762 825
763=item contrast $r, $g, $b, $a, $img 826=item contrast $r, $g, $b, $a, $img
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792latter in a white picture. 855latter in a white picture.
793 856
794Due to idiosyncrasies in the underlying XRender extension, biases less 857Due to idiosyncrasies in the underlying XRender extension, biases less
795than zero can be I<very> slow. 858than zero can be I<very> slow.
796 859
860You can also try the experimental(!) C<muladd> operator.
861
797=cut 862=cut
798 863
799 sub contrast($$;$$;$) { 864 sub contrast($$;$$;$) {
800 my $img = pop; 865 my $img = pop;
801 my ($r, $g, $b, $a) = @_; 866 my ($r, $g, $b, $a) = @_;
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816 $a = 1 if @_ < 4; 881 $a = 1 if @_ < 4;
817 882
818 $img = $img->clone; 883 $img = $img->clone;
819 $img->brightness ($r, $g, $b, $a); 884 $img->brightness ($r, $g, $b, $a);
820 $img 885 $img
886 }
887
888=item muladd $mul, $add, $img # EXPERIMENTAL
889
890First multipliesthe pixels by C<$mul>, then adds C<$add>. This cna be used
891to implement brightness and contrast at the same time, with a wider value
892range than contrast and brightness operators.
893
894Due to numerous bugs in XRender implementations, it can also introduce a
895number of visual artifacts.
896
897Example: increase contrast by a factor of C<$c> without changing image
898brightness too much.
899
900 muladd $c, (1 - $c) * 0.5, $img
901
902=cut
903
904 sub muladd($$$) {
905 $_[2]->muladd ($_[0], $_[1])
821 } 906 }
822 907
823=item blur $radius, $img 908=item blur $radius, $img
824 909
825=item blur $radius_horz, $radius_vert, $img 910=item blur $radius_horz, $radius_vert, $img
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870C<keep> block so it only is reevaluated as required. 955C<keep> block so it only is reevaluated as required.
871 956
872Putting the blur into a C<keep> block will make sure the blur is only done 957Putting the blur into a C<keep> block will make sure the blur is only done
873once, while the C<rootalign> is still done each time the window moves. 958once, while the C<rootalign> is still done each time the window moves.
874 959
875 rootlign keep { blur 10, root } 960 rootalign keep { blur 10, root }
876 961
877This leaves the question of how to force reevaluation of the block, 962This leaves the question of how to force reevaluation of the block,
878in case the root background changes: If expression inside the block 963in case the root background changes: If expression inside the block
879is sensitive to some event (root background changes, window geometry 964is sensitive to some event (root background changes, window geometry
880changes), then it will be reevaluated automatically as needed. 965changes), then it will be reevaluated automatically as needed.
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932 1017
933# compiles a parsed expression 1018# compiles a parsed expression
934sub set_expr { 1019sub set_expr {
935 my ($self, $expr) = @_; 1020 my ($self, $expr) = @_;
936 1021
937 $self->{root} = []; 1022 $self->{root} = []; # the outermost frame
938 $self->{expr} = $expr; 1023 $self->{expr} = $expr;
939 $self->recalculate; 1024 $self->recalculate;
940} 1025}
941 1026
942# takes a hash of sensitivity indicators and installs watchers 1027# takes a hash of sensitivity indicators and installs watchers
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1004 1089
1005 # set environment to evaluate user expression 1090 # set environment to evaluate user expression
1006 1091
1007 local $self = $arg_self; 1092 local $self = $arg_self;
1008 local $HOME = $ENV{HOME}; 1093 local $HOME = $ENV{HOME};
1009 local $frame = []; 1094 local $frame = $self->{root};
1010 1095
1011 ($x, $y, $w, $h) = $self->background_geometry ($self->{border}); 1096 ($x, $y, $w, $h) = $self->background_geometry ($self->{border});
1012 1097
1013 # evaluate user expression 1098 # evaluate user expression
1014 1099

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