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Comparing rxvt-unicode/src/perl/background (file contents):
Revision 1.72 by root, Mon Jul 2 02:01:41 2012 UTC vs.
Revision 1.75 by root, Fri Aug 10 20:07:11 2012 UTC

… …
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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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.
161 185
162=head2 COLOUR SPECIFICATIONS 186=head2 COLOUR SPECIFICATIONS
163 187
164Whenever an oprator expects a "colour", then this can be specified in one 188Whenever an operator expects a "colour", then this can be specified in one
165of two ways: Either as string with an X11 colour specification, such as: 189of two ways: Either as string with an X11 colour specification, such as:
166 190
167 "red" # named colour 191 "red" # named colour
168 "#f00" # simple rgb 192 "#f00" # simple rgb
169 "[50]red" # red with 50% alpha 193 "[50]red" # red with 50% alpha
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827latter in a white picture. 851latter in a white picture.
828 852
829Due to idiosyncrasies in the underlying XRender extension, biases less 853Due to idiosyncrasies in the underlying XRender extension, biases less
830than zero can be I<very> slow. 854than zero can be I<very> slow.
831 855
856You can also try the experimental(!) C<muladd> operator.
857
832=cut 858=cut
833 859
834 sub contrast($$;$$;$) { 860 sub contrast($$;$$;$) {
835 my $img = pop; 861 my $img = pop;
836 my ($r, $g, $b, $a) = @_; 862 my ($r, $g, $b, $a) = @_;
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851 $a = 1 if @_ < 4; 877 $a = 1 if @_ < 4;
852 878
853 $img = $img->clone; 879 $img = $img->clone;
854 $img->brightness ($r, $g, $b, $a); 880 $img->brightness ($r, $g, $b, $a);
855 $img 881 $img
882 }
883
884=item muladd $mul, $add, $img # EXPERIMENTAL
885
886First multipliesthe pixels by C<$mul>, then adds C<$add>. This cna be used
887to implement brightness and contrast at the same time, with a wider value
888range than contrast and brightness operators.
889
890Due to numerous bugs in XRender implementations, it can also introduce a
891number of visual artifacts.
892
893Example: increase contrast by a factor of C<$c> without changing image
894brightness too much.
895
896 muladd $c, (1 - $c) * 0.5, $img
897
898=cut
899
900 sub muladd($$$) {
901 $_[2]->muladd ($_[0], $_[1])
856 } 902 }
857 903
858=item blur $radius, $img 904=item blur $radius, $img
859 905
860=item blur $radius_horz, $radius_vert, $img 906=item blur $radius_horz, $radius_vert, $img
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905C<keep> block so it only is reevaluated as required. 951C<keep> block so it only is reevaluated as required.
906 952
907Putting the blur into a C<keep> block will make sure the blur is only done 953Putting the blur into a C<keep> block will make sure the blur is only done
908once, while the C<rootalign> is still done each time the window moves. 954once, while the C<rootalign> is still done each time the window moves.
909 955
910 rootlign keep { blur 10, root } 956 rootalign keep { blur 10, root }
911 957
912This leaves the question of how to force reevaluation of the block, 958This leaves the question of how to force reevaluation of the block,
913in case the root background changes: If expression inside the block 959in case the root background changes: If expression inside the block
914is sensitive to some event (root background changes, window geometry 960is sensitive to some event (root background changes, window geometry
915changes), then it will be reevaluated automatically as needed. 961changes), then it will be reevaluated automatically as needed.
… …
967 1013
968# compiles a parsed expression 1014# compiles a parsed expression
969sub set_expr { 1015sub set_expr {
970 my ($self, $expr) = @_; 1016 my ($self, $expr) = @_;
971 1017
972 $self->{root} = []; 1018 $self->{root} = []; # the outermost frame
973 $self->{expr} = $expr; 1019 $self->{expr} = $expr;
974 $self->recalculate; 1020 $self->recalculate;
975} 1021}
976 1022
977# takes a hash of sensitivity indicators and installs watchers 1023# takes a hash of sensitivity indicators and installs watchers
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1039 1085
1040 # set environment to evaluate user expression 1086 # set environment to evaluate user expression
1041 1087
1042 local $self = $arg_self; 1088 local $self = $arg_self;
1043 local $HOME = $ENV{HOME}; 1089 local $HOME = $ENV{HOME};
1044 local $frame = []; 1090 local $frame = $self->{root};
1045 1091
1046 ($x, $y, $w, $h) = $self->background_geometry ($self->{border}); 1092 ($x, $y, $w, $h) = $self->background_geometry ($self->{border});
1047 1093
1048 # evaluate user expression 1094 # evaluate user expression
1049 1095

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