Fix a partial rendering problem

testing/embedder_test.cpp

 // Copyright 2015 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.
 
 #include "testing/embedder_test.h"
 
 #include <limits.h>
 
 #include <list>
 #include <string>
 #include <utility>
 #include <vector>
 
 #include "public/fpdf_dataavail.h"
+#include "public/fpdf_edit.h"
 #include "public/fpdf_text.h"
 #include "public/fpdfview.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/test_support.h"
 #include "testing/utils/path_service.h"
 
 #ifdef PDF_ENABLE_V8
 #include "v8/include/v8.h"
 #include "v8/include/v8-platform.h"
 #endif  // PDF_ENABLE_V8
@@ skipping 181 matching lines @@
   if (!page) {
     return nullptr;
   }
   FORM_DoPageAAction(page, form_handle_, FPDFPAGE_AACTION_OPEN);
   return page;
 }
 
 FPDF_BITMAP EmbedderTest::RenderPage(FPDF_PAGE page) {
   int width = static_cast<int>(FPDF_GetPageWidth(page));
   int height = static_cast<int>(FPDF_GetPageHeight(page));
-  FPDF_BITMAP bitmap = FPDFBitmap_Create(width, height, 0);
-  FPDFBitmap_FillRect(bitmap, 0, 0, width, height, 0xFFFFFFFF);
+  int alpha = FPDFPage_HasTransparency(page) ? 1 : 0;
+  FPDF_BITMAP bitmap = FPDFBitmap_Create(width, height, alpha);
+  FPDF_DWORD fill_color = alpha ? 0x00000000 : 0xFFFFFFFF;
+  FPDFBitmap_FillRect(bitmap, 0, 0, width, height, fill_color);
   FPDF_RenderPageBitmap(bitmap, page, 0, 0, width, height, 0, 0);
   FPDF_FFLDraw(form_handle_, bitmap, page, 0, 0, width, height, 0, 0);
   return bitmap;
 }
 
 void EmbedderTest::UnloadPage(FPDF_PAGE page) {
   FORM_DoPageAAction(page, form_handle_, FPDFPAGE_AACTION_CLOSE);
   FORM_OnBeforeClosePage(page, form_handle_);
   FPDF_ClosePage(page);
 }
@@ skipping 54 matching lines @@
 }
 
 // Can't use gtest-provided main since we need to stash the path to the
 // executable in order to find the external V8 binary data files.
 int main(int argc, char** argv) {
   g_exe_path_ = argv[0];
   testing::InitGoogleTest(&argc, argv);
   testing::InitGoogleMock(&argc, argv);
   return RUN_ALL_TESTS();
 }