handle antialiased rendering as premultiplied

core/fpdfapi/render/cpdf_renderstatus.cpp

 // Copyright 2016 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
 
 #include "core/fpdfapi/render/cpdf_renderstatus.h"
 
 #include <algorithm>
 #include <memory>
@@ skipping 858 matching lines @@
     int height,
     int flags) {
   std::unique_ptr<CFX_DIBitmap> pBitmap(new CFX_DIBitmap);
   if (!pBitmap->Create(width, height,
                        pPattern->colored() ? FXDIB_Argb : FXDIB_8bppMask)) {
     return nullptr;
   }
   CFX_FxgeDevice bitmap_device;
   bitmap_device.Attach(pBitmap.get(), false, nullptr, false);
   pBitmap->Clear(0);
+#if defined _SKIA_SUPPORT_PATHS_
+  pBitmap->SetIsOffscreen(true);
+#endif
   CFX_FloatRect cell_bbox = pPattern->bbox();
   pPattern->pattern_to_form()->TransformRect(cell_bbox);
   pObject2Device->TransformRect(cell_bbox);
   CFX_FloatRect bitmap_rect(0.0f, 0.0f, (FX_FLOAT)width, (FX_FLOAT)height);
   CFX_Matrix mtAdjust;
   mtAdjust.MatchRect(bitmap_rect, cell_bbox);
   CFX_Matrix mtPattern2Bitmap = *pObject2Device;
   mtPattern2Bitmap.Concat(mtAdjust);
   CPDF_RenderOptions options;
   if (!pPattern->colored())
     options.m_ColorMode = RENDER_COLOR_ALPHA;
 
   flags |= RENDER_FORCE_HALFTONE;
   options.m_Flags = flags;
   CPDF_RenderContext context(pDoc, pCache);
   context.AppendLayer(pPattern->form(), &mtPattern2Bitmap);
   context.Render(&bitmap_device, &options, nullptr);
+#if defined _SKIA_SUPPORT_PATHS_
+  pBitmap->UnPreMultiply();
+#endif
   return pBitmap;
 }
 
 bool IsAvailableMatrix(const CFX_Matrix& matrix) {
   if (matrix.a == 0 || matrix.d == 0)
     return matrix.b != 0 && matrix.c != 0;
 
   if (matrix.b == 0 || matrix.c == 0)
     return matrix.a != 0 && matrix.d != 0;
 
@@ skipping 603 matching lines @@
   if (!isolated && (m_pDevice->GetRenderCaps() & FXRC_GET_BITS)) {
     oriDevice.reset(new CFX_DIBitmap);
     if (!m_pDevice->CreateCompatibleBitmap(oriDevice.get(), width, height))
       return true;
     m_pDevice->GetDIBits(oriDevice.get(), rect.left, rect.top);
   }
   if (!bitmap_device.Create(width, height, FXDIB_Argb, oriDevice.get()))
     return true;
   CFX_DIBitmap* bitmap = bitmap_device.GetBitmap();
   bitmap->Clear(0);
+#ifdef _SKIA_SUPPORT_PATHS_
+  bitmap->SetIsOffscreen(true);
+#endif
   CFX_Matrix new_matrix = *pObj2Device;
   new_matrix.TranslateI(-rect.left, -rect.top);
   new_matrix.Scale(scaleX, scaleY);
   std::unique_ptr<CFX_DIBitmap> pTextMask;
   if (bTextClip) {
     pTextMask.reset(new CFX_DIBitmap);
     if (!pTextMask->Create(width, height, FXDIB_8bppMask))
       return true;
 
     pTextMask->Clear(0);
@@ skipping 1098 matching lines @@
   } else if (pFunc) {
     int size = dest_pitch * height;
     for (int i = 0; i < size; i++) {
       dest_buf[i] = transfers[src_buf[i]];
     }
   } else {
     FXSYS_memcpy(dest_buf, src_buf, dest_pitch * height);
   }
   return pMask.release();
 }