Supports High DPI mode.

When launching an application on the text size larger than 120 DPI, Windows runs the application on the DPI-virtualization mode to hide the text size from it. Unfortunately, this virtualization mode causes some problems when using a custom frame, such as we cannot click system buttons. To fix this issue, this change disables the DPI-virtualization mode on Vista or later.

BUG=1715,36939
TEST=Run chrome.exe on the screen resolution higher than 120 DPI.
Review URL: http://codereview.chromium.org/2867031

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@52446 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 22 insertions, 0 deletions

diff --git a/app/win_util.cc b/app/win_util.cc
index b043db3..46a4f92 100644
--- a/app/win_util.cc
+++ b/app/win_util.cc
@@ -23,6 +23,7 @@
 #include "base/scoped_comptr_win.h"
 #include "base/scoped_handle.h"
 #include "base/scoped_handle_win.h"
+#include "base/scoped_native_library.h"
 #include "base/string_util.h"
 #include "base/win_util.h"
 #include "gfx/codec/png_codec.h"
@@ -582,4 +583,18 @@ void SetAppIdForWindow(const std::wstring& app_id, HWND hwnd) {
   base::UnloadNativeLibrary(shell32_library);
 }
 
+void CallSetProcessDPIAware() {
+  // This functionality is only available on Vista or later.
+  if (win_util::GetWinVersion() < win_util::WINVERSION_VISTA)
+    return;
+
+  base::ScopedNativeLibrary user32(
+      FilePath(base::GetNativeLibraryName(L"user32")));
+  typedef BOOL (*SetProcessDPIAwareFunc)();
+  SetProcessDPIAwareFunc set_process_dpi_aware =
+      (SetProcessDPIAwareFunc)user32.GetFunctionPointer("SetProcessDPIAware");
+  if (set_process_dpi_aware)
+    set_process_dpi_aware();
+}
+
 }  // namespace win_util
diff --git a/app/win_util.h b/app/win_util.h
index 6e2812e..9d745eb 100644
--- a/app/win_util.h
+++ b/app/win_util.h
@@ -215,6 +215,13 @@ extern const int kAutoHideTaskbarThicknessPx;
 // do not group together on the Win7 task bar.
 void SetAppIdForWindow(const std::wstring& app_id, HWND hwnd);
 
+// Calls SetProcessDPIAware() to declare this application is DPI-aware and to
+// disable the DPI virtualization of Windows. Unfortunately, calling this
+// function after creating a window confuses some APIs, i.e. some APIs still
+// have the DPI virtualization enabled after calling SetProcessDPIAware().
+// Therefore, we need to call this function before creating the first window.
+void CallSetProcessDPIAware();
+
 }  // namespace win_util
 
 #endif  // APP_WIN_UTIL_H_