handle antialiased rendering as premultiplied

core/fxge/fx_dib.h

Index: core/fxge/fx_dib.h
diff --git a/core/fxge/fx_dib.h b/core/fxge/fx_dib.h
index daf2cdf9a5067f046957962e84c8626abb3bd7f8..3605a8cbc19d5620555d64724c8c2ab2c412e1c4 100644
--- a/core/fxge/fx_dib.h
+++ b/core/fxge/fx_dib.h
@@ -371,10 +371,12 @@ class CFX_DIBitmap : public CFX_DIBSource {
 
   bool ConvertColorScale(uint32_t forecolor, uint32_t backcolor);
 
-#ifdef _SKIA_SUPPORT_PATHS_
+#if defined _SKIA_SUPPORT_PATHS_
   bool IsMarkedForUnPreMultiply() const { return m_bUnPreMultiply; }
-
+  bool IsOffscreen() const { return m_bIsOffscreen; }
   void MarkForUnPreMultiply(bool mark) { m_bUnPreMultiply = mark; }
+  void SetIsOffscreen(bool isOff) { m_bIsOffscreen = isOff; }
+  void UnPreMultiply();
 #endif
 
  protected:
@@ -382,7 +384,8 @@ class CFX_DIBitmap : public CFX_DIBSource {
 
   uint8_t* m_pBuffer;
   bool m_bExtBuf;
-#ifdef _SKIA_SUPPORT_PATHS_
+#if defined _SKIA_SUPPORT_PATHS_
+  bool m_bIsOffscreen;
   bool m_bUnPreMultiply;
 #endif
 };