add in High DPI support (aka Retina)

- based on Jørgen's patch with a few bug fixes

src/video/SDL_sysvideo.h

@@ -224,6 +224,7 @@ struct SDL_VideoDevice
     void (*GL_UnloadLibrary) (_THIS);
       SDL_GLContext(*GL_CreateContext) (_THIS, SDL_Window * window);
     int (*GL_MakeCurrent) (_THIS, SDL_Window * window, SDL_GLContext context);
+    void (*GL_GetDrawableSize) (_THIS, SDL_Window * window, int *w, int *h);
     int (*GL_SetSwapInterval) (_THIS, int interval);
     int (*GL_GetSwapInterval) (_THIS);
     void (*GL_SwapWindow) (_THIS, SDL_Window * window);

src/video/SDL_video.c

@@ -1187,6 +1187,7 @@ SDL_Window *
 SDL_CreateWindow(const char *title, int x, int y, int w, int h, Uint32 flags)
 {
     SDL_Window *window;
+    const char *hint;
 
     if (!_this) {
         /* Initialize the video system if needed */
@@ -1245,6 +1246,17 @@ SDL_CreateWindow(const char *title, int x, int y, int w, int h, Uint32 flags)
     window->flags = ((flags & CREATE_FLAGS) | SDL_WINDOW_HIDDEN);
     window->brightness = 1.0f;
     window->next = _this->windows;
+
+    /* Unless the user has specified the high-DPI disabling hint, respect the
+     * SDL_WINDOW_ALLOW_HIGHDPI flag.
+     */
+    hint = SDL_GetHint(SDL_HINT_VIDEO_HIGHDPI_DISABLED);
+    if (!hint || *hint != '1') {
+        if ((flags & SDL_WINDOW_ALLOW_HIGHDPI)) {
+            window->flags |= SDL_WINDOW_ALLOW_HIGHDPI;
+        }
+    }
+
     if (_this->windows) {
         _this->windows->prev = window;
     }
@@ -2813,6 +2825,17 @@ SDL_GL_GetCurrentContext(void)
     return (SDL_GLContext)SDL_TLSGet(_this->current_glctx_tls);
 }
 
+void SDL_GL_GetDrawableSize(SDL_Window * window, int *w, int *h)
+{
+    CHECK_WINDOW_MAGIC(window, );
+
+    if (_this->GL_GetDrawableSize) {
+        _this->GL_GetDrawableSize(_this, window, w, h);
+    } else {
+        SDL_GetWindowSize(window, w, h);
+    }
+}
+
 int
 SDL_GL_SetSwapInterval(int interval)
 {

src/video/cocoa/SDL_cocoaopengl.h

@@ -54,6 +54,8 @@ extern void Cocoa_GL_UnloadLibrary(_THIS);
 extern SDL_GLContext Cocoa_GL_CreateContext(_THIS, SDL_Window * window);
 extern int Cocoa_GL_MakeCurrent(_THIS, SDL_Window * window,
                                 SDL_GLContext context);
+extern void Cocoa_GL_GetDrawableSize(_THIS, SDL_Window * window,
+                                     int * w, int * h);
 extern int Cocoa_GL_SetSwapInterval(_THIS, int interval);
 extern int Cocoa_GL_GetSwapInterval(_THIS);
 extern void Cocoa_GL_SwapWindow(_THIS, SDL_Window * window);

src/video/cocoa/SDL_cocoaopengl.m

@@ -35,6 +35,18 @@
 
 #define DEFAULT_OPENGL  "/System/Library/Frameworks/OpenGL.framework/Libraries/libGL.dylib"
 
+#if MAC_OS_X_VERSION_MAX_ALLOWED < 1070
+/* New methods for converting to and from backing store pixels, taken from
+ * AppKite/NSView.h in 10.8 SDK. */
+@interface NSView (Backing)
+- (NSPoint)convertPointToBacking:(NSPoint)aPoint;
+- (NSPoint)convertPointFromBacking:(NSPoint)aPoint;
+- (NSSize)convertSizeToBacking:(NSSize)aSize;
+- (NSSize)convertSizeFromBacking:(NSSize)aSize;
+- (NSRect)convertRectToBacking:(NSRect)aRect;
+- (NSRect)convertRectFromBacking:(NSRect)aRect;
+@end
+#endif
 
 #ifndef kCGLPFAOpenGLProfile
 #define kCGLPFAOpenGLProfile 99
@@ -294,6 +306,28 @@ Cocoa_GL_MakeCurrent(_THIS, SDL_Window * window, SDL_GLContext context)
     return 0;
 }
 
+void
+Cocoa_GL_GetDrawableSize(_THIS, SDL_Window * window, int * w, int * h)
+{
+    SDL_WindowData *windata = (SDL_WindowData *) window->driverdata;
+    NSView *contentView = [windata->nswindow contentView];
+    NSRect viewport = [contentView bounds];
+
+    /* This gives us the correct viewport for a Retina-enabled view, only
+     * supported on 10.7+. */
+    if ([contentView respondsToSelector:@selector(convertRectToBacking:)]) {
+        viewport = [contentView convertRectToBacking:viewport];
+    }
+
+    if (w) {
+        *w = viewport.size.width;
+    }
+
+    if (h) {
+        *h = viewport.size.height;
+    }
+}
+
 int
 Cocoa_GL_SetSwapInterval(_THIS, int interval)
 {

src/video/cocoa/SDL_cocoavideo.m

@@ -119,6 +119,7 @@ Cocoa_CreateDevice(int devindex)
     device->GL_UnloadLibrary = Cocoa_GL_UnloadLibrary;
     device->GL_CreateContext = Cocoa_GL_CreateContext;
     device->GL_MakeCurrent = Cocoa_GL_MakeCurrent;
+    device->GL_GetDrawableSize = Cocoa_GL_GetDrawableSize;
     device->GL_SetSwapInterval = Cocoa_GL_SetSwapInterval;
     device->GL_GetSwapInterval = Cocoa_GL_GetSwapInterval;
     device->GL_SwapWindow = Cocoa_GL_SwapWindow;

src/video/cocoa/SDL_cocoawindow.m

@@ -34,6 +34,13 @@
 #include "SDL_cocoamouse.h"
 #include "SDL_cocoaopengl.h"
 
+#if MAC_OS_X_VERSION_MAX_ALLOWED < 1070
+/* Taken from AppKit/NSOpenGLView.h in 10.8 SDK. */
+@interface NSView (NSOpenGLSurfaceResolution)
+- (BOOL)wantsBestResolutionOpenGLSurface;
+- (void)setWantsBestResolutionOpenGLSurface:(BOOL)flag;
+@end
+#endif
 
 static Uint32 s_moveHack;
 
@@ -739,6 +746,13 @@ Cocoa_CreateWindow(_THIS, SDL_Window * window)
     /* Create a default view for this window */
     rect = [nswindow contentRectForFrameRect:[nswindow frame]];
     NSView *contentView = [[SDLView alloc] initWithFrame:rect];
+
+    if ((window->flags & SDL_WINDOW_ALLOW_HIGHDPI) > 0) {
+        if ([contentView respondsToSelector:@selector(setWantsBestResolutionOpenGLSurface:)]) {
+            [contentView setWantsBestResolutionOpenGLSurface:YES];
+        }
+    }
+
     [nswindow setContentView: contentView];
     [contentView release];