add optional bitflags to control which aspect of each layer's paint is applied

git-svn-id: http://skia.googlecode.com/svn/trunk@1083 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 32 insertions, 8 deletions

diff --git a/include/effects/SkLayerDrawLooper.h b/include/effects/SkLayerDrawLooper.h
index d35d70d7dd..682a9dc119 100644
--- a/include/effects/SkLayerDrawLooper.h
+++ b/include/effects/SkLayerDrawLooper.h
@@ -9,17 +9,38 @@ class SkLayerDrawLooper : public SkDrawLooper {
 public:
             SkLayerDrawLooper();
     virtual ~SkLayerDrawLooper();
+
+    enum Bits {
+        kAlpha_Bit      = 1 << 0,   //!< use this layer's alpha
+        kColor_Bit      = 1 << 1,   //!< use this layer's color
+        kStyle_Bit      = 1 << 2,   //!< use this layer's Style/stroke settings
+        kTextSkewX_Bit  = 1 << 3,   //!< use this layer's textskewx
+        kPathEffect_Bit = 1 << 4,   //!< use this layer's patheffect
+        kMaskFilter_Bit = 1 << 5,   //!< use this layer's maskfilter
+        kShader_Bit     = 1 << 6,   //!< use this layer's shader
+        kColorFilter_Bit = 1 << 7,  //!< use this layer's colorfilter
+        kXfermode_Bit   = 1 << 8,   //!< use this layer's xfermode
+        
+        kEntirePaint_Bits = -1,      //!< use this layer's paint entirely
+    };
+    typedef int32_t BitFlags;
     
-    /** Call for each layer you want to add (from top to bottom).
-        This returns a paint you can modify, but that ptr is only valid until
-        the next call made to this object.
+    /**
+     *  Call for each layer you want to add (from top to bottom).
+     *  This returns a paint you can modify, but that ptr is only valid until
+     *  the next call made to this object.
+     *
+     *  The optional bits parameter specifies which aspects of this paint
+     *  should replace the paint that is passed to the draw call. If 0 is
+     *  specified, then this layer's paint will be ignored.
      */
-    SkPaint* addLayer(SkScalar dx, SkScalar dy);
+    SkPaint* addLayer(SkScalar dx, SkScalar dy, BitFlags = kEntirePaint_Bits);
     
-    /** Helper for addLayer() which passes (0, 0) for the offset parameters
+    /**
+     *  Helper for addLayer() which passes (0, 0) for the offset parameters
      */
-    SkPaint* addLayer() {
-        return this->addLayer(0, 0);
+    SkPaint* addLayer(BitFlags bits = kEntirePaint_Bits) {
+        return this->addLayer(0, 0, bits);
     }
     
     // overrides from SkDrawLooper
@@ -43,6 +64,7 @@ private:
         Rec*    fNext;
         SkPaint fPaint;
         SkPoint fOffset;
+        uint32_t fBits;
         
         static Rec* Reverse(Rec*);
     };
@@ -51,7 +73,9 @@ private:
 
     // state-machine during the init/next cycle
     Rec* fCurrRec;
-    
+
+    static void ApplyBits(SkPaint* dst, const SkPaint& src, BitFlags bits);
+
     class MyRegistrar : public SkFlattenable::Registrar {
     public:
         MyRegistrar();