handle antialiased rendering as premultiplied

fpdfsdk/fpdfview.cpp

 // 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
 
 #include "public/fpdfview.h"
 
 #include <memory>
 #include <utility>
@@ skipping 580 matching lines @@
   CPDF_PageRenderContext* pContext = new CPDF_PageRenderContext;
   pPage->SetRenderContext(pdfium::WrapUnique(pContext));
   CFX_FxgeDevice* pDevice = new CFX_FxgeDevice;
   pContext->m_pDevice.reset(pDevice);
   CFX_DIBitmap* pBitmap = CFXBitmapFromFPDFBitmap(bitmap);
   pDevice->Attach(pBitmap, !!(flags & FPDF_REVERSE_BYTE_ORDER), nullptr, false);
 
   FPDF_RenderPage_Retail(pContext, page, start_x, start_y, size_x, size_y,
                          rotate, flags, true, nullptr);
 
+#ifdef _SKIA_SUPPORT_PATHS_
+  pBitmap->UnPreMultiply();
+#endif
   pPage->SetRenderContext(nullptr);
 }
 
 #ifdef _SKIA_SUPPORT_
 DLLEXPORT FPDF_RECORDER STDCALL FPDF_RenderPageSkp(FPDF_PAGE page,
                                                    int size_x,
                                                    int size_y) {
   CPDF_Page* pPage = CPDFPageFromFPDFPage(page);
   if (!pPage)
     return nullptr;
@@ skipping 497 matching lines @@
   if (!buffer) {
     *buflen = len;
   } else if (*buflen >= len) {
     memcpy(buffer, utf16Name.c_str(), len);
     *buflen = len;
   } else {
     *buflen = -1;
   }
   return (FPDF_DEST)pDestObj;
 }