Prepare ScreenWin To Use Per-Monitor DPI

base/win/win_util.cc

Index: base/win/win_util.cc
diff --git a/base/win/win_util.cc b/base/win/win_util.cc
index ce59baa287d4e9820ea4428492c27834d5e37b05..535034570671140b154e32fcc1c4b56fff8aa5d7 100644
--- a/base/win/win_util.cc
+++ b/base/win/win_util.cc
@@ -16,6 +16,7 @@
 #include <roapi.h>
 #include <sddl.h>
 #include <setupapi.h>
+#include <shellscalingapi.h>
 #include <shlwapi.h>
 #include <signal.h>
 #include <stddef.h>
@@ -597,5 +598,31 @@ void DisableFlicks(HWND hwnd) {
           TABLET_DISABLE_FLICKFALLBACKKEYS));
 }
 
+bool IsProcessPerMonitorDpiAware() {
+  static enum class PerMonitorDpiAware {
+    UNKNOWN = 0,
+    PER_MONITOR_DPI_UNAWARE,
+    PER_MONITOR_DPI_AWARE,
+  } per_monitor_dpi_aware = PerMonitorDpiAware::UNKNOWN;
+  if (per_monitor_dpi_aware == PerMonitorDpiAware::UNKNOWN) {
+    per_monitor_dpi_aware = PerMonitorDpiAware::PER_MONITOR_DPI_UNAWARE;
+    HMODULE shcore_dll = ::LoadLibrary(L"shcore.dll");
+    if (shcore_dll) {
+      using GetProcessDpiAwarenessPtr =
+          HRESULT (WINAPI *) (HANDLE, PROCESS_DPI_AWARENESS*);
+      GetProcessDpiAwarenessPtr process_dpi_awareness_func =
+          reinterpret_cast<GetProcessDpiAwarenessPtr>(
+              ::GetProcAddress(shcore_dll, "GetProcessDpiAwareness"));

[scottmg, 2016/06/27 17:55:04]

How about

auto get_process_dpi_awareness =
reinterpret_cast<decltype(::GetProcessDpiAwareness)*>(::GetProcAddress(...));

, rather than redeclaring the function prototype?

[robliao, 2016/06/27 18:39:29]

This is much nicer. Done!

+      if (process_dpi_awareness_func) {
+        PROCESS_DPI_AWARENESS awareness;
+        if (SUCCEEDED(process_dpi_awareness_func(nullptr, &awareness)) &&
+            awareness == PROCESS_PER_MONITOR_DPI_AWARE)
+          per_monitor_dpi_aware = PerMonitorDpiAware::PER_MONITOR_DPI_AWARE;
+      }
+    }
+  }
+  return per_monitor_dpi_aware == PerMonitorDpiAware::PER_MONITOR_DPI_AWARE;
+}
+
 }  // namespace win
 }  // namespace base