1 files changed, 54 insertions, 0 deletions
diff --git a/mozglue/misc/WindowsDpiInitialization.h b/mozglue/misc/WindowsDpiInitialization.h
new file mode 100644
index 0000000000..5943d50526
--- /dev/null
+++ b/mozglue/misc/WindowsDpiInitialization.h
@@ -0,0 +1,54 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef MOZILLA_MOZGLUE_MISC_WINDOWSDPIINITIALIZATION_H_
+#define MOZILLA_MOZGLUE_MISC_WINDOWSDPIINITIALIZATION_H_
+#include "mozilla/Types.h"
+
+namespace mozilla {
+
+// The result codes that may be returned from WindowsDpiInitialization()
+enum class WindowsDpiInitializationResult : uint32_t {
+  Success,
+  FindSetProcessDpiAwarenessContextFailed,
+  SetProcessDpiAwarenessContextFailed,
+  FindSetProcessDpiAwarenessFailed,
+  SetProcessDpiAwarenessFailed,
+  SetProcessDPIAwareFailed,
+};
+
+// Get a string representation of any WindowsDpiInitializationResult value
+inline const char* WindowsDpiInitializationResultString(
+    WindowsDpiInitializationResult result) {
+  switch (result) {
+    case WindowsDpiInitializationResult::Success:
+      return "Success";
+    case WindowsDpiInitializationResult::
+        FindSetProcessDpiAwarenessContextFailed:
+      return "Failed to find SetProcessDpiAwarenessContext";
+    case WindowsDpiInitializationResult::SetProcessDpiAwarenessContextFailed:
+      return "SetProcessDpiAwarenessContext failed";
+    case WindowsDpiInitializationResult::FindSetProcessDpiAwarenessFailed:
+      return "Failed to find SetProcessDpiAwareness";
+    case WindowsDpiInitializationResult::SetProcessDpiAwarenessFailed:
+      return "SetProcessDpiAwareness failed";
+    case WindowsDpiInitializationResult::SetProcessDPIAwareFailed:
+      return "SetProcessDPIAware failed";
+    default:
+      return "Unknown result";
+  }
+}
+
+// Initialize DPI awareness to the best available for the current OS
+// According to MSDN, this will be:
+// Per-Monitor V2 for Windows 10 Creators Update (1703) and later
+// Per-Monitor V1 for Windows 8.1 and later
+// System DPI for Vista and later (we don't support anything older)
+// https://docs.microsoft.com/en-us/windows/win32/hidpi/high-dpi-desktop-application-development-on-windows
+MFBT_API WindowsDpiInitializationResult WindowsDpiInitialization();
+
+}  // namespace mozilla
+
+#endif  // MOZILLA_MOZGLUE_MISC_WINDOWSDPIINITIALIZATION_H_