Add Surface::PixelDivisions which detects 'retina' displays that use

multiple display pixels per logical pixel.
Likely will only return >1 for Apple displays.
Can be used for finer placement of elements.

1 files changed, 12 insertions, 0 deletions

diff --git a/win32/PlatWin.cxx b/win32/PlatWin.cxx
index 452bb49bc..014c09793 100644
--- a/win32/PlatWin.cxx
+++ b/win32/PlatWin.cxx
@@ -482,6 +482,7 @@ public:
 	bool Initialised() override;
 	void PenColour(ColourDesired fore) override;
 	int LogPixelsY() override;
+	int PixelDivisions() override;
 	int DeviceHeightFont(int points) override;
 	void MoveTo(int x_, int y_) override;
 	void LineTo(int x_, int y_) override;
@@ -637,6 +638,11 @@ int SurfaceGDI::LogPixelsY() {
 	return logPixelsY;
 }
 
+int SurfaceGDI::PixelDivisions() {
+	// Win32 uses device pixels.
+	return 1;
+}
+
 int SurfaceGDI::DeviceHeightFont(int points) {
 	return ::MulDiv(points, LogPixelsY(), 72);
 }
@@ -1170,6 +1176,7 @@ public:
 	void PenColour(ColourDesired fore) override;
 	void D2DPenColour(ColourDesired fore, int alpha=255);
 	int LogPixelsY() override;
+	int PixelDivisions() override;
 	int DeviceHeightFont(int points) override;
 	void MoveTo(int x_, int y_) override;
 	void LineTo(int x_, int y_) override;
@@ -1367,6 +1374,11 @@ int SurfaceD2D::LogPixelsY() {
 	return logPixelsY;
 }
 
+int SurfaceD2D::PixelDivisions() {
+	// Win32 uses device pixels.
+	return 1;
+}
+
 int SurfaceD2D::DeviceHeightFont(int points) {
 	return ::MulDiv(points, LogPixelsY(), 72);
 }