Multiple DPI Tracking for ScreenWin

ui/gfx/screen_win.h

Index: ui/gfx/screen_win.h
diff --git a/ui/gfx/screen_win.h b/ui/gfx/screen_win.h
index 2849e6623de312f412e32cc5a544a69080a9717b..6cb9e34660b91ea443b288c6349316e3f2bca993 100644
--- a/ui/gfx/screen_win.h
+++ b/ui/gfx/screen_win.h
@@ -21,6 +21,7 @@ namespace gfx {
 class Display;
 class Point;
 class Rect;
+class Size;
 
 namespace win {
 
@@ -34,6 +35,61 @@ class GFX_EXPORT ScreenWin : public Screen {
   ScreenWin();
   ~ScreenWin() override;
 
+  // Converts a screen pixel point to a DIP point.
+  // The DPI scale is performed relative to the display containing the screen
+  // pixel point maintaining a constant origin on both Screen and DIP (same as
+  // Windows).
+  static Point ScreenToDIPPoint(const Point& pixel_point);
+
+  // Converts a DIP point to a screen pixel point.
+  // The DPI scale is performed relative to the display containing the DIP point
+  // maintaining a constant origin on both Screen and DIP (same as Windows).
+  static Point DIPToScreenPoint(const Point& dip_point);
+
+  // Converts a client pixel point relative to |hwnd| to a DIP point.
+  // The DPI scale is performed relative to |hwnd| using an origin of (0, 0).
+  static Point ClientToDIPPoint(HWND hwnd, const Point& client_point);
+
+  // Converts a client DIP point relative to |hwnd| to a client pixel point.
+  // The DPI scale is performed relative to |hwnd| using an origin of (0, 0).
+  static Point DIPToClientPoint(HWND hwnd, const Point& dip_point);
+
+  // WARNING: there is no right way to scale sizes and rects. The implementation
+  // of these strives to maintain a constant size by scaling the size
+  // independent of the origin. An alternative is to get the enclosing rect,

[oshima, 2016/02/11 22:59:58]

The comment isn't clear to me. can you elaborate? (I understand what each
methods are doing)

[robliao, 2016/02/12 01:52:53]

This was taken from the original DPI scaling code. Updated.

+  // which is the right way for some situations. Understand which you need
+  // before blindly assuming this is the right way.
+
+  // Converts a screen rect to a DIP rect.
+  // The DPI scale is performed relative to the display nearest to |hwnd|
+  // maintaining a constant origin on both Screen and DIP (same as Windows).
+  // If |hwnd| is null, scaling will be performed to the display nearest to
+  // |pixel_bounds|.
+  static Rect ScreenToDIPRect(HWND hwnd, const Rect& pixel_bounds);
+
+  // Converts a DIP rect to a screen rect.
+  // The DPI scale is performed relative to the display nearest to |hwnd|
+  // maintaining a constant origin on both Screen and DIP (same as Windows).
+  // If |hwnd| is null, scaling will be performed to the display nearest to
+  // |dip_bounds|.
+  static Rect DIPToScreenRect(HWND hwnd, const Rect& dip_bounds);
+
+  // Converts a client rect to a DIP rect.
+  // The DPI scale is performed relative to |hwnd| using an origin of (0, 0).
+  static Rect ClientToDIPRect(HWND hwnd, const Rect& pixel_bounds);
+
+  // Converts a DIP rect to a client rect.
+  // The DPI scale is performed relative to |hwnd| using an origin of (0, 0).
+  static Rect DIPToClientRect(HWND hwnd, const Rect& dip_bounds);
+
+  // Converts a screen size to a DIP size.
+  // The DPI scale is performed relative to the display nearest to |hwnd|.
+  static Size ScreenToDIPSize(HWND hwnd, const Size& size_in_pixels);
+
+  // Converts a DIP size to a screen size.
+  // The DPI scale is performed relative to the display nearest to |hwnd|.
+  static Size DIPToScreenSize(HWND hwnd, const Size& dip_size);
+
   // Returns the HWND associated with the NativeView.
   virtual HWND GetHWNDFromNativeView(NativeView window) const;
 
@@ -53,6 +109,10 @@ class GFX_EXPORT ScreenWin : public Screen {
   gfx::Display GetPrimaryDisplay() const override;
   void AddObserver(DisplayObserver* observer) override;
   void RemoveObserver(DisplayObserver* observer) override;
+  gfx::Rect ScreenToDIPRectInWindow(
+      NativeView view, const gfx::Rect& screen_rect) const override;
+  gfx::Rect DIPToScreenRectInWindow(
+      NativeView view, const gfx::Rect& dip_rect) const override;
 
   void UpdateFromDisplayInfos(
       const std::vector<gfx::win::DisplayInfo>& display_infos);
@@ -81,12 +141,28 @@ class GFX_EXPORT ScreenWin : public Screen {
   gfx::win::ScreenWinDisplay GetScreenWinDisplayNearestScreenPoint(
       const Point& screen_point) const;
 
+  // Returns the ScreenWinDisplay closest to or enclosing |dip_point|.
+  gfx::win::ScreenWinDisplay GetScreenWinDisplayNearestDIPPoint(
+    const Point& dip_point) const;
+
+  // Returns the ScreenWinDisplay closest to or enclosing |dip_rect|.
+  gfx::win::ScreenWinDisplay ScreenWin::GetScreenWinDisplayNearestDIPRect(
+    const Rect& dip_rect) const;
+
   // Returns the ScreenWinDisplay corresponding to the primary monitor.
   gfx::win::ScreenWinDisplay GetPrimaryScreenWinDisplay() const;
 
   gfx::win::ScreenWinDisplay GetScreenWinDisplay(
       const MONITORINFOEX& monitor_info) const;
 
+  static float GetScaleFactorForHWND(HWND hwnd);
+
+  // Returns the result of calling |getter| with |value| on the global
+  // ScreenWin if it exists, otherwise return the default ScreenWinDisplay.
+  template <typename Getter, typename GetterType>
+  static gfx::win::ScreenWinDisplay GetScreenWinDisplayVia(Getter getter,
+                                                           GetterType value);
+
   // Helper implementing the DisplayObserver handling.
   gfx::DisplayChangeNotifier change_notifier_;