flesh out gradient shaders

core/fxge/include/fx_ge.h

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #ifndef CORE_FXGE_INCLUDE_FX_GE_H_
 #define CORE_FXGE_INCLUDE_FX_GE_H_
 
 #include "core/fxge/include/fx_dib.h"
@@ skipping 585 matching lines @@
                                  uint32_t color,
                                  int alpha_flag = 0,
                                  void* pIccTransform = NULL) {
     return FALSE;
   }
 
   virtual void* GetPlatformSurface() const { return NULL; }
   virtual int GetDriverType() const { return 0; }
   virtual void ClearDriver() {}
 
-  virtual FX_BOOL DrawShading(CPDF_ShadingPattern* pPattern,
-                              CFX_Matrix* pMatrix,
+  virtual FX_BOOL DrawShading(const CPDF_ShadingPattern* pPattern,
+                              const CFX_Matrix* pMatrix,
+                              const FX_RECT& clip_rect,
                               int alpha,
                               FX_BOOL bAlphaMode) {
     return false;
   }
 };
 
 class IFX_PSOutput {
  public:
   virtual void Release() = 0;
   virtual void OutputPS(const FX_CHAR* str, int len) = 0;
@@ skipping 106 matching lines @@
   void FindPSFontGlyph(CFX_FaceCache* pFaceCache,
                        CFX_Font* pFont,
                        const FXTEXT_CHARPOS& charpos,
                        int& ps_fontnum,
                        int& ps_glyphindex);
 
   void WritePSBinary(const uint8_t* data, int len);
 };
 
 #endif  // CORE_FXGE_INCLUDE_FX_GE_H_