From b240ff08e80f4fc4cfd0a56f7a89abcf04728fa9 Mon Sep 17 00:00:00 2001
From: Lars Doucet <lars.doucet@gmail.com>
Date: Tue, 12 Jan 2016 09:15:28 -0600
Subject: [PATCH] Expose display device DPI

---
 lime/system/Display.hx                |  5 +++++
 lime/system/System.hx                 | 14 ++++++++++++++
 project/include/system/System.h       |  1 +
 project/src/ExternalInterface.cpp     |  7 +++++++
 project/src/backend/sdl/SDLSystem.cpp | 21 +++++++++++++++++++++
 5 files changed, 48 insertions(+)

diff --git a/lime/system/Display.hx b/lime/system/Display.hx
index 5e3788686..140afba97 100644
--- a/lime/system/Display.hx
+++ b/lime/system/Display.hx
@@ -19,6 +19,11 @@ class Display {
 	
 	public var id (default, null):Int;
 	
+	/**
+	 * Pixel density of the display
+	 */
+	public var dpi (default, null): { diagonal:Float, horizontal:Float, vertical:Float };
+	
 	/**
 	 * The name of the device, such as "Samsung SyncMaster P2350", "iPhone 6", "Occulus Rift DK2", etc.
 	 **/
diff --git a/lime/system/System.hx b/lime/system/System.hx
index c6b0712ba..c2accfd79 100644
--- a/lime/system/System.hx
+++ b/lime/system/System.hx
@@ -163,6 +163,19 @@ class System {
 			}
 			
 			display.currentMode = display.supportedModes[displayInfo.currentMode];
+			
+			var dpi:Dynamic = lime_system_get_display_dpi (id);
+			
+			if (dpi != null) {
+				
+				display.dpi = { vertical:0, horizontal:0, diagonal:0 };
+				
+				display.dpi.vertical   = dpi.vertical;
+				display.dpi.horizontal = dpi.horizontal;
+				display.dpi.diagonal   = dpi.diagonal;
+				
+			}
+			
 			return display;
 			
 		}
@@ -421,6 +434,7 @@ class System {
 	@:cffi private static function lime_system_set_allow_screen_timeout (value:Bool):Bool;
 	@:cffi private static function lime_system_get_directory (type:Int, company:String, title:String):Dynamic;
 	@:cffi private static function lime_system_get_display (index:Int):Dynamic;
+	@:cffi private static function lime_system_get_display_dpi (index:Int):Dynamic;
 	@:cffi private static function lime_system_get_num_displays ():Int;
 	@:cffi private static function lime_system_get_timer ():Float;
 	#end
diff --git a/project/include/system/System.h b/project/include/system/System.h
index 971e4109a..b185d2b1b 100644
--- a/project/include/system/System.h
+++ b/project/include/system/System.h
@@ -28,6 +28,7 @@ namespace lime {
 			static bool GetAllowScreenTimeout ();
 			static const char* GetDirectory (SystemDirectory type, const char* company, const char* title);
 			static value GetDisplay (int id);
+			static value GetDisplayDPI (int id);
 			static int GetNumDisplays ();
 			static double GetTimer ();
 			static bool SetAllowScreenTimeout (bool allow);
diff --git a/project/src/ExternalInterface.cpp b/project/src/ExternalInterface.cpp
index a4c8c3317..300afd506 100644
--- a/project/src/ExternalInterface.cpp
+++ b/project/src/ExternalInterface.cpp
@@ -1160,6 +1160,12 @@ namespace lime {
 	}
 	
 	
+	value lime_system_get_display_dpi (int id) {
+		
+		return System::GetDisplayDPI (id);
+		
+	}
+	
 	int lime_system_get_num_displays () {
 		
 		return System::GetNumDisplays ();
@@ -1512,6 +1518,7 @@ namespace lime {
 	DEFINE_PRIME0 (lime_system_get_allow_screen_timeout);
 	DEFINE_PRIME3 (lime_system_get_directory);
 	DEFINE_PRIME1 (lime_system_get_display);
+	DEFINE_PRIME1 (lime_system_get_display_dpi);
 	DEFINE_PRIME0 (lime_system_get_num_displays);
 	DEFINE_PRIME0 (lime_system_get_timer);
 	DEFINE_PRIME1 (lime_system_set_allow_screen_timeout);
diff --git a/project/src/backend/sdl/SDLSystem.cpp b/project/src/backend/sdl/SDLSystem.cpp
index 5fec0b286..2310c1b0e 100644
--- a/project/src/backend/sdl/SDLSystem.cpp
+++ b/project/src/backend/sdl/SDLSystem.cpp
@@ -304,6 +304,27 @@ namespace lime {
 		
 	}
 	
+	value System::GetDisplayDPI (int id) {
+		
+		value dpi = alloc_empty_object ();
+		
+		int id_diagonal   = val_id ("diagonal");
+		int id_horizontal = val_id ("horizontal");
+		int id_vertical   = val_id ("vertical");
+		
+		float ddpi = 0.0;
+		float hdpi = 0.0;
+		float vdpi = 0.0;
+		
+		SDL_GetDisplayDPI (id, &ddpi, &hdpi, &vdpi);
+		
+		alloc_field (dpi, id_diagonal  , alloc_float (ddpi));
+		alloc_field (dpi, id_horizontal, alloc_float (hdpi));
+		alloc_field (dpi, id_vertical  , alloc_float (vdpi));
+		
+		return dpi;
+		
+	}
 	
 	int System::GetNumDisplays () {