Added methods to create and read from file-backed metafiles to the Wi…

…ndows Emf class.

BUG=None
TEST=Unittests

Review URL: http://codereview.chromium.org/3538003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@60994 0039d316-1c4b-4281-b951-d872f2087c98

printing/emf_win.cc

@@ -4,6 +4,7 @@
 
 #include "printing/emf_win.h"
 
+#include "base/file_path.h"
 #include "base/histogram.h"
 #include "base/logging.h"
 #include "base/scoped_ptr.h"
@@ -60,13 +61,31 @@ bool Emf::CreateDc(HDC sibling, const RECT* rect) {
   return hdc_ != NULL;
 }
 
+bool Emf::CreateFileBackedDc(HDC sibling, const RECT* rect,
+                             const FilePath& path) {
+  DCHECK(!emf_ && !hdc_);
+  DCHECK(!path.empty());
+  hdc_ = CreateEnhMetaFile(sibling, path.value().c_str(), rect, NULL);
+  DCHECK(hdc_);
+  return hdc_ != NULL;
+}
+
+
 bool Emf::CreateFromData(const void* buffer, uint32 size) {
   DCHECK(!emf_ && !hdc_);
   emf_ = SetEnhMetaFileBits(size, reinterpret_cast<const BYTE*>(buffer));
   DCHECK(emf_);
   return emf_ != NULL;
 }
 
+bool Emf::CreateFromFile(const FilePath& metafile_path) {
+  DCHECK(!emf_ && !hdc_);
+  emf_ = GetEnhMetaFile(metafile_path.value().c_str());
+  DCHECK(emf_);
+  return emf_ != NULL;
+}
+
+
 bool Emf::CloseDc() {
   DCHECK(!emf_ && hdc_);
   emf_ = CloseEnhMetaFile(hdc_);

printing/emf_win.h

@@ -10,6 +10,8 @@
 
 #include "base/basictypes.h"
 
+class FilePath;
+
 namespace gfx {
 class Rect;
 }
@@ -33,9 +35,15 @@ class Emf {
   // optional.
   bool CreateDc(HDC sibling, const RECT* rect);
 
+  // Similar to the above method but the metafile is backed by a file.
+  bool CreateFileBackedDc(HDC sibling, const RECT* rect, const FilePath& path);
+
   // Load a EMF data stream. buffer contains EMF data.
   bool CreateFromData(const void* buffer, uint32 size);
 
+    // Load an EMF file.
+  bool CreateFromFile(const FilePath& metafile_path);
+
   // TODO(maruel): CreateFromFile(). If ever used. Maybe users would like to
   // have the ability to save web pages to an EMF file? Afterward, it is easy to
   // convert to PDF or PS.

printing/emf_win_unittest.cc

@@ -33,11 +33,11 @@ class EmfPrintingTest : public testing::Test {
   }
 };
 
+const uint32 EMF_HEADER_SIZE = 128;
+
 }  // namespace
 
 TEST(EmfTest, DC) {
-  static const uint32 EMF_HEADER_SIZE = 128;
-
   // Simplest use case.
   printing::Emf emf;
   RECT rect = {100, 100, 200, 200};
@@ -154,3 +154,36 @@ TEST_F(EmfPrintingTest, PageBreak) {
   }
 }
 
+TEST(EmfTest, FileBackedDC) {
+  // Simplest use case.
+  printing::Emf emf;
+  RECT rect = {100, 100, 200, 200};
+  HDC hdc = CreateCompatibleDC(NULL);
+  EXPECT_TRUE(hdc != NULL);
+  FilePath metafile_path;
+  EXPECT_TRUE(file_util::CreateTemporaryFile(&metafile_path));
+  EXPECT_TRUE(emf.CreateFileBackedDc(hdc, &rect, metafile_path));
+  EXPECT_TRUE(emf.hdc() != NULL);
+  // In theory, you'd use the HDC with GDI functions here.
+  EXPECT_TRUE(emf.CloseDc());
+
+  uint32 size = emf.GetDataSize();
+  EXPECT_EQ(size, EMF_HEADER_SIZE);
+  std::vector<BYTE> data;
+  EXPECT_TRUE(emf.GetData(&data));
+  EXPECT_EQ(data.size(), size);
+  emf.CloseEmf();
+  int64 file_size = 0;
+  file_util::GetFileSize(metafile_path, &file_size);
+  EXPECT_EQ(size, file_size);
+  EXPECT_TRUE(DeleteDC(hdc));
+
+  // Playback the data.
+  hdc = CreateCompatibleDC(NULL);
+  EXPECT_TRUE(hdc);
+  EXPECT_TRUE(emf.CreateFromFile(metafile_path));
+  RECT output_rect = {0, 0, 10, 10};
+  EXPECT_TRUE(emf.Playback(hdc, &output_rect));
+  EXPECT_TRUE(DeleteDC(hdc));
+}
+