Create the transparency mask only when it is really needed.

That is, when the border is not opaque.

1 files changed, 33 insertions, 25 deletions

diff --git a/mkindex.pl b/mkindex.pl
index 1c6010c..bfb41dd 100755
--- a/mkindex.pl
+++ b/mkindex.pl
@@ -505,9 +505,9 @@ sub annotate {
     undef $ds;
     die "Error: Couldn't inverse affine transformation\n" unless $ok;
 
-    my $img = Image::Magick::->new();
-    $img->Read( $filename );
-    my ($width, $height) = $img->Get(qw/width height/);
+    my $raster = Image::Magick::->new();
+    $raster->Read( $filename );
+    my ($width, $height) = $raster->Get(qw/width height/);
 
     my @draw = ( fill => 'none'
                , strokewidth => $config{border}
@@ -517,6 +517,8 @@ sub annotate {
               # To get the list of supported fonts: `convert -list font`.
               , font => $config{font}
               , pointsize => $config{fontsize}
+              , fill => $config{fontcolor}
+              , gravity => 'Center'
               );
 
     # Separate RGB and alpha channels. This complicated business is
@@ -525,26 +527,30 @@ sub annotate {
     # areas (due to the default composition, which multiplies the
     # values.
     #
-    # To get the list of supported colors: `convert -list color`.
+    # To get the list of known color names: `convert -list color`.
     my $pix = Image::Magick::->new();
     my ($r, $g, $b, $a) = $pix->QueryColor( $config{bordercolor} );
     my $max = (2 << ($pix->Get('depth') - 1)) - 1.;
     undef $pix;
-    ($r,$g,$b,$a) = map { $_ * 100. / $max } ($r,$g,$b,$a);
+    ($r,$g,$b,$a) = map { ($_ // 0) * 100. / $max } ($r,$g,$b,$a);
     my ($b_rgb, $b_alpha) = ("RGB($r%,$g%,$b%)", 'GRAY('.(100-$a).'%)');
 
     my $rgb= Image::Magick::->new( size => "${width}x${height}" );
     $rgb->Read( 'xc:none' );
 
-    my $mask = Image::Magick::->new( size => "${width}x${height}" );
-    $mask->Read( 'xc:black' );
-    # We really want 'Gray', but a non-linear Gray. See
-    # http://www.imagemagick.org/script/color-management.php
-    # for the trick:
-    #   convert myimage.png -set colorspace RGB -colorspace gray myRGBimage.png
-    # (Also, setting the 'colorspace' during the object creation was
-    # useless.)
-    $mask->Set( colorspace => 'RGB' );
+    my $mask;
+    if ($a > 0) {
+        &debug( "Adding a transparency mask (border opacity: $a%)." );
+        $mask = Image::Magick::->new( size => "${width}x${height}" );
+        $mask->Read( 'xc:black' );
+        # We really want 'Gray', but a non-linear Gray. See
+        # http://www.imagemagick.org/script/color-management.php
+        # for the trick:
+        #   convert img.png -set colorspace RGB -colorspace gray RGBimg.png
+        # (Also, setting the 'colorspace' during the object creation was
+        # useless.)
+        $mask->Set( colorspace => 'RGB' );
+    }
 
     foreach my $map (@mapset) {
         # In case the projection have changed, the map may have been rotated,
@@ -558,7 +564,7 @@ sub annotate {
         # Add the borders. We do that after the text to draw over in
         # case of intersection.
         $rgb->Draw( @draw, stroke => $b_rgb,   points => $points );
-        $mask->Draw(@draw, stroke => $b_alpha, points => $points );
+        $mask->Draw(@draw, stroke => $b_alpha, points => $points ) if $mask;
 
         # Get the extremes of this polygon.
         my ($lx,$uy,$rx,$ly);
@@ -574,26 +580,28 @@ sub annotate {
 
         # Add the caption. ('gravity' is relative to the 'geometry'.)
         # Everything that's not in the cell's region is trimmed away.
-        my @ann = ( @ann, geometry => $cell, gravity => 'Center'
-                  , text => $map->{text} );
-        $img->MogrifyRegion( $cell, 'Annotate',
-                             @ann, fill => $config{fontcolor} );
+        $raster->MogrifyRegion( $cell, 'Annotate'
+                              , @ann
+                              , geometry => $cell
+                              , text => $map->{text} );
     }
 
     # Change the colorspace (now to non-linear gray), and turn off
     # the alpha channel. Then copy this (shared) channel back into the
     # RGB annotation channel.
-    $mask->Set( colorspace => 'Gray', alpha => 'Off' );
-    $rgb->Composite( image => $mask, compose => 'CopyOpacity' );
-    undef $mask;
+    if ($mask) {
+        $mask->Set( colorspace => 'Gray', alpha => 'Off' );
+        $rgb->Composite( image => $mask, compose => 'CopyOpacity' );
+        undef $mask;
+    }
 
     # Merge all the annotations into the mosaic.
-    $img->Composite( image => $rgb, compose => 'Over' );
+    $raster->Composite( image => $rgb, compose => 'Over' );
     undef $rgb;
 
     binmode STDOUT if $index =~ /^(?:[[:alnum:]]*:)?-$/; # Useful for pipes
-    $img->Write($index);
-    undef $img;
+    $raster->Write($index);
+    undef $raster;
 }
 
 __END__