     [ check-ole32-error ] [ |ScriptStringFree void* deref ] bi* ;
 
 : set-dc-colors ( dc font -- )
-    [ background>> color>RGB SetBkColor drop ]
-    [ foreground>> color>RGB SetTextColor drop ] 2bi ;
+    dup background>> >rgba alpha>> 1 number= [
+        ! No transparency needed, set colors from the font.
+        [ background>> color>RGB SetBkColor drop ]
+        [ foreground>> color>RGB SetTextColor drop ] 2bi
+    ] [
+        ! Draw white text on black background. The resulting grayscale
+        ! image will be used as transparency mask for the actual color.
+        drop
+        [ COLOR: black color>RGB SetBkColor drop ]
+        [ COLOR: white color>RGB SetTextColor drop ] bi
+    ] if ;
 
 : selection-start/end ( script-string -- iMinSel iMaxSel )
     string>> dup selection? [ [ start>> ] [ end>> ] bi ] [ drop 0 0 ] if ;

! Copyright (C) 2009 Slava Pestov.
! See http://factorcode.org/license.txt for BSD license.
USING: accessors alien.c-types alien.data arrays assocs cache
classes.struct combinators destructors fonts init io.encodings.string
io.encodings.utf16n kernel literals locals math namespaces sequences
windows.errors windows.fonts windows.gdi32 windows.offscreen
windows.ole32 windows.types windows.usp10 ;
IN: windows.uniscribe

TUPLE: script-string < disposable font string metrics ssa size image ;

    FALSE ! fDisabled
    ScriptStringOut check-ole32-error ;

! The image is a grayscale rendering of a text string. We want the text to
! have the given color. Move the blue channel of the image (any color
! channel will do, since it's grayscale) into its alpha channel, and make
! the entire image a rectangle of the given color with varying
! transparency.
:: color-to-alpha ( image color -- image' )
    image color >rgba-components drop [ 255 * >integer ] tri@ 3array [
        swap first suffix -rot image set-pixel-at
    ] curry each-pixel image RGBA >>component-order ;

:: render-image ( dc ssa script-string -- image )
    script-string size>> :> size
    size dc
    [ ssa size script-string draw-script-string ] make-bitmap-image
    script-string font>> [ foreground>> ] [ background>> ] bi
    >rgba alpha>> 1 number= [ drop ] [ color-to-alpha ] if ;

: set-dc-font ( dc font -- )
    cache-font SelectObject win32-error=0/f ;
