--- a/CairoGraphicsContext.st	Mon Mar 21 22:28:05 2016 +0000
+++ b/CairoGraphicsContext.st	Wed Mar 16 09:56:21 2016 +0000
@@ -6,7 +6,7 @@
 	instanceVariableNames:'cr'
 	classVariableNames:''
 	poolDictionaries:'Cairo::FontSlant Cairo::FontWeight Cairo::Format Cairo::Status
-		Cairo::Antialias'
+		Cairo::Antialias Cairo::Extend'
 	category:'Cairo-Compatibility'
 !
 
@@ -169,10 +169,25 @@
 mask:aForm
     "set the drawing mask"
 
-    #todo.  
     super mask: aForm.
+    cr notNil ifTrue:[ 
+        self maskSet.
+    ].
 
-    "Modified: / 27-02-2016 / 15:20:04 / Jan Vrany <jan.vrany@fit.cvut.cz>"
+    "Modified (format): / 08-03-2016 / 21:22:25 / Jan Vrany <jan.vrany@fit.cvut.cz>"
+!
+
+maskOrigin:aPoint
+    "set the origin of the mask-pattern"
+
+    super maskOrigin: aPoint.
+    gcId notNil ifTrue:[
+        mask notNil ifTrue:[   
+            self maskSet.
+        ].
+    ].
+
+    "Created: / 08-03-2016 / 21:23:15 / Jan Vrany <jan.vrany@fit.cvut.cz>"
 !
 
 paint: aColor
@@ -923,6 +938,46 @@
     aBlock ensure:[ self transformation: savedTransformation ].
 
     "Created: / 26-02-2016 / 09:29:57 / Jan Vrany <jan.vrany@fit.cvut.cz>"
+!
+
+maskSet
+    "Either mask or markOrigin changed. Update Cairo's source pattern"
+
+    | maskImage w h maskSurface maskPattern sourceSurface sourceContext sourcePattern |
+
+    mask isNil ifTrue:[ 
+        cr source: paint.
+        ^ self.
+    ].
+
+    maskImage := mask asImage.
+    w := maskImage width.
+    h := maskImage height.
+    [
+        sourceSurface := Cairo::Surface newImageWithFormat: CAIRO_FORMAT_ARGB32 width: w height: h similarTo: cr surface.
+        maskImage depth == 1 ifTrue:[
+            maskSurface := maskImage asSurfaceWithFormat: CAIRO_FORMAT_A1 similarTo: sourceSurface.
+            maskPattern := Cairo::Pattern surface: maskSurface.
+            maskPattern extend: CAIRO_EXTEND_REPEAT.
+        ] ifFalse:[ 
+            self error: 'Not yet supported'
+        ].
+        sourceContext := sourceSurface cairo.
+        maskOrigin notNil ifTrue:[ 
+            maskPattern matrix: (Cairo::Matrix translate: maskOrigin negated).
+        ].
+        sourceContext source: cr source.               
+        sourceContext mask: maskPattern.
+    ] ensure:[
+        sourceContext notNil ifTrue:[sourceContext release].
+        maskPattern notNil ifTrue:[maskPattern release].
+        maskSurface notNil ifTrue:[maskSurface release].
+    ].
+    sourcePattern := Cairo::Pattern surface: sourceSurface.
+    sourcePattern extend: CAIRO_EXTEND_REPEAT.
+    cr source: sourcePattern.
+
+    "Created: / 08-03-2016 / 21:21:39 / Jan Vrany <jan.vrany@fit.cvut.cz>"
 ! !
 
 !CairoGraphicsContext class methodsFor:'documentation'!