win: gfx::EnableHighDPISupport is dropped

zcbenz · zcbenz · commit 02c04cbf68ec · 2015-01-27T13:19:18.000-08:00
diff --git a/atom/app/atom_main.cc b/atom/app/atom_main.cc
@@ -13,11 +13,14 @@
 #include <fcntl.h>
 
 #include <windows.h>
+#include <shellscalingapi.h>
+#include <tchar.h>
 #include <shellapi.h>
 
 #include "atom/app/atom_main_delegate.h"
 #include "atom/common/crash_reporter/win/crash_service_main.h"
 #include "base/environment.h"
+#include "base/win/windows_version.h"
 #include "content/public/app/startup_helper_win.h"
 #include "sandbox/win/src/sandbox_types.h"
 #include "ui/gfx/win/dpi.h"
@@ -37,6 +40,48 @@ int Start(int argc, char *argv[]);
 
 #if defined(OS_WIN)
 
+namespace {
+
+// Win8.1 supports monitor-specific DPI scaling.
+bool SetProcessDpiAwarenessWrapper(PROCESS_DPI_AWARENESS value) {
+  typedef HRESULT(WINAPI *SetProcessDpiAwarenessPtr)(PROCESS_DPI_AWARENESS);
+  SetProcessDpiAwarenessPtr set_process_dpi_awareness_func =
+      reinterpret_cast<SetProcessDpiAwarenessPtr>(
+          GetProcAddress(GetModuleHandleA("user32.dll"),
+                         "SetProcessDpiAwarenessInternal"));
+  if (set_process_dpi_awareness_func) {
+    HRESULT hr = set_process_dpi_awareness_func(value);
+    if (SUCCEEDED(hr)) {
+      VLOG(1) << "SetProcessDpiAwareness succeeded.";
+      return true;
+    } else if (hr == E_ACCESSDENIED) {
+      LOG(ERROR) << "Access denied error from SetProcessDpiAwareness. "
+          "Function called twice, or manifest was used.";
+    }
+  }
+  return false;
+}
+
+// This function works for Windows Vista through Win8. Win8.1 must use
+// SetProcessDpiAwareness[Wrapper].
+BOOL SetProcessDPIAwareWrapper() {
+  typedef BOOL(WINAPI *SetProcessDPIAwarePtr)(VOID);
+  SetProcessDPIAwarePtr set_process_dpi_aware_func =
+      reinterpret_cast<SetProcessDPIAwarePtr>(
+      GetProcAddress(GetModuleHandleA("user32.dll"),
+                      "SetProcessDPIAware"));
+  return set_process_dpi_aware_func &&
+    set_process_dpi_aware_func();
+}
+
+void EnableHighDPISupport() {
+  if (!SetProcessDpiAwarenessWrapper(PROCESS_SYSTEM_DPI_AWARE)) {
+    SetProcessDPIAwareWrapper();
+  }
+}
+
+}  // namespace
+
 int APIENTRY wWinMain(HINSTANCE instance, HINSTANCE, wchar_t* cmd, int) {
   int argc = 0;
   wchar_t** wargv = ::CommandLineToArgvW(::GetCommandLineW(), &argc);
@@ -103,8 +148,11 @@ int APIENTRY wWinMain(HINSTANCE instance, HINSTANCE, wchar_t* cmd, int) {
   content::InitializeSandboxInfo(&sandbox_info);
   atom::AtomMainDelegate delegate;
 
-  // Now chrome relies on a regkey to enable high dpi support.
-  gfx::EnableHighDPISupport();
+  // We don't want to set DPI awareness on pre-Win7 because we don't support
+  // DirectWrite there. GDI fonts are kerned very badly, so better to leave
+  // DPI-unaware and at effective 1.0. See also ShouldUseDirectWrite().
+  if (base::win::GetVersion() >= base::win::VERSION_WIN7)
+    EnableHighDPISupport();
 
   content::ContentMainParams params(&delegate);
   params.instance = instance;
