--- rxvt-unicode/src/perl/background	2012/07/14 08:42:54	1.74
+++ rxvt-unicode/src/perl/background	2014/12/13 12:24:33	1.89
@@ -1,12 +1,12 @@
 #! perl
 
-#:META:X_RESOURCE:%.expr:string:background expression
-#:META:X_RESOURCE:%.border:boolean:respect the terminal border
-#:META:X_RESOURCE:%.interval:seconds:minimum time between updates
+#:META:RESOURCE:%.expr:string:background expression
+#:META:RESOURCE:%.border:boolean:respect the terminal border
+#:META:RESOURCE:%.interval:seconds:minimum time between updates
 
 =head1 NAME
 
-   background - manage terminal background
+background - manage terminal background
 
 =head1 SYNOPSIS
 
@@ -14,6 +14,30 @@
          --background-border
          --background-interval seconds
 
+=head1 QUICK AND DIRTY CHEAT SHEET
+
+Just load a random jpeg image and tile the background with it without
+scaling or anything else:
+
+   load "/path/to/img.jpg"
+
+The same, but use mirroring/reflection instead of tiling:
+
+   mirror load "/path/to/img.jpg"
+
+Load an image and scale it to exactly fill the terminal window:
+
+   scale keep { load "/path/to/img.jpg" }
+
+Implement pseudo-transparency by using a suitably-aligned root pixmap
+as window background:
+
+   rootalign root
+
+Likewise, but keep a blurred copy:
+
+   rootalign keep { blur 10, root }
+
 =head1 DESCRIPTION
 
 This extension manages the terminal background by creating a picture that
@@ -257,7 +281,7 @@
 our %_IMG_CACHE;
 our $HOME;
 our ($self, $frame);
-our ($x, $y, $w, $h);
+our ($x, $y, $w, $h, $focus);
 
 # enforce at least this interval between updates
 our $MIN_INTERVAL = 6/59.951;
@@ -286,7 +310,7 @@
 mode.
 
 If the image is already in memory (e.g. because another terminal instance
-uses it), then the in-memory copy us returned instead.
+uses it), then the in-memory copy is returned instead.
 
 =item load_uc $path
 
@@ -400,6 +424,8 @@
       $base
    }
 
+=back
+
 =head2 TILING MODES
 
 The following operators modify the tiling mode of an image, that is, the
@@ -500,7 +526,7 @@
 window is the full window by default, and the character area only when in
 border-respect mode).
 
-Using these functions make your expression sensitive to window moves.
+Using these functions makes your expression sensitive to window moves.
 
 These functions are mainly useful to align images to the root window.
 
@@ -511,11 +537,13 @@
 
 =item TW
 
+=item TH
+
 Return the width (C<TW>) and height (C<TH>) of the terminal window (the
 terminal window is the full window by default, and the character area only
 when in border-respect mode).
 
-Using these functions make your expression sensitive to window resizes.
+Using these functions makes your expression sensitive to window resizes.
 
 These functions are mainly useful to scale images, or to clip images to
 the window size to conserve memory.
@@ -525,12 +553,29 @@
 
    clip move -TX, -TY, keep { blur 5, root }
 
+=item FOCUS
+
+Returns a boolean indicating whether the terminal window has keyboard
+focus, in which case it returns true.
+
+Using this function makes your expression sensitive to focus changes.
+
+A common use case is to fade the background image when the terminal loses
+focus, often together with the C<-fade> command line option. In fact,
+there is a special function for just that use case: C<focus_fade>.
+
+Example: use two entirely different background images, depending on
+whether the window has focus.
+
+   FOCUS ? keep { load "has_focus.jpg" } : keep { load "no_focus.jpg" }
+
 =cut
 
-   sub TX() { $frame->[FR_AGAIN]{position} = 1; $x }
-   sub TY() { $frame->[FR_AGAIN]{position} = 1; $y }
-   sub TW() { $frame->[FR_AGAIN]{size}     = 1; $w }
-   sub TH() { $frame->[FR_AGAIN]{size}     = 1; $h }
+   sub TX   () { $frame->[FR_AGAIN]{position} = 1; $x     }
+   sub TY   () { $frame->[FR_AGAIN]{position} = 1; $y     }
+   sub TW   () { $frame->[FR_AGAIN]{size}     = 1; $w     }
+   sub TH   () { $frame->[FR_AGAIN]{size}     = 1; $h     }
+   sub FOCUS() { $frame->[FR_AGAIN]{focus}    = 1; $focus }
 
 =item now
 
@@ -587,7 +632,7 @@
 larger than the image, then the tiling mode defines how the extra pixels
 will be filled.
 
-If C<$x> an C<$y> are missing, then C<0> is assumed for both.
+If C<$x> and C<$y> are missing, then C<0> is assumed for both.
 
 If C<$width> and C<$height> are missing, then the window size will be
 assumed.
@@ -615,7 +660,7 @@
 Scales the image by the given factors in horizontal
 (C<$width>) and vertical (C<$height>) direction.
 
-If only one factor is give, it is used for both directions.
+If only one factor is given, it is used for both directions.
 
 If no factors are given, scales the image to the window size without
 keeping aspect.
@@ -750,7 +795,7 @@
 Rotates the image clockwise by C<$degrees> degrees, around the point at
 C<$center_x> and C<$center_y> (specified as factor of image width/height).
 
-Example: rotate the image by 90 degrees around it's center.
+Example: rotate the image by 90 degrees around its center.
 
    rotate 0.5, 0.5, 90, keep { load "$HOME/mybg.png" }
 
@@ -791,6 +836,16 @@
       $_[1]->tint ($_[0])
    }
 
+=item shade $factor, $img
+
+Shade the image by the given factor.
+
+=cut
+
+   sub shade($$) {
+      $_[1]->shade ($_[0])
+   }
+
 =item contrast $factor, $img
 
 =item contrast $r, $g, $b, $img
@@ -829,6 +884,8 @@
 Due to idiosyncrasies in the underlying XRender extension, biases less
 than zero can be I<very> slow.
 
+You can also try the experimental(!) C<muladd> operator.
+
 =cut
 
    sub contrast($$;$$;$) {
@@ -855,6 +912,26 @@
       $img
    }
 
+=item muladd $mul, $add, $img # EXPERIMENTAL
+
+First multiplies the pixels by C<$mul>, then adds C<$add>. This can be used
+to implement brightness and contrast at the same time, with a wider value
+range than contrast and brightness operators.
+
+Due to numerous bugs in XRender implementations, it can also introduce a
+number of visual artifacts.
+
+Example: increase contrast by a factor of C<$c> without changing image
+brightness too much.
+
+   muladd $c, (1 - $c) * 0.5, $img
+
+=cut
+
+   sub muladd($$$) {
+      $_[2]->muladd ($_[0], $_[1])
+   }
+
 =item blur $radius, $img
 
 =item blur $radius_horz, $radius_vert, $img
@@ -874,6 +951,39 @@
       $img->blur ($_[0], @_ >= 2 ? $_[1] : $_[0])
    }
 
+=item focus_fade $img
+
+=item focus_fade $factor, $img
+
+=item focus_fade $factor, $color, $img
+
+Fades the image by the given factor (and colour) when focus is lost (the
+same as the C<-fade>/C<-fadecolor> command line options, which also supply
+the default values for C<factor> and C<$color>. Unlike with C<-fade>, the
+C<$factor> is a real value, not a percentage value (that is, 0..1, not
+0..100).
+
+Example: do the right thing when focus fading is requested.
+
+   focus_fade load "mybg.jpg";
+
+=cut
+
+   sub focus_fade($;$$) {
+      my $img = pop;
+
+      return $img
+         if FOCUS;
+
+      my $fade   = @_ >= 1 ? $_[0] : defined $self->resource ("fade") ? $self->resource ("fade") * 0.01 : 0;
+      my $color  = @_ >= 2 ? $_[1] : $self->resource ("color+" . urxvt::Color_fade);
+
+      $img = $img->tint ($color)         if $color ne "rgb:00/00/00";
+      $img = $img->muladd (1 - $fade, 0) if $fade;
+
+      $img
+   }
+
 =back
 
 =head2 OTHER STUFF
@@ -1020,6 +1130,12 @@
    } else {
       delete $state->{rootpmap};
    }
+
+   if ($again->{focus}) {
+      $state->{focus} = $self->on (focus_in => $cb, focus_out => $cb);
+   } else {
+      delete $state->{focus};
+   }
 }
 
 # evaluate the current bg expression
@@ -1044,6 +1160,7 @@
    local $frame = $self->{root};
 
    ($x, $y, $w, $h) = $self->background_geometry ($self->{border});
+   $focus           = $self->focus;
 
    # evaluate user expression
 
@@ -1071,7 +1188,7 @@
    # set background pixmap
 
    $self->set_background ($img, $self->{border});
-   $self->scr_recolour (0);
+   $self->scr_recolor (0);
    $self->want_refresh;
 }