# HG changeset patch
# User Edward Rudd <urkle@outoforder.cc>
# Date 1370362716 14400
# Node ID de459517506d4526a8d2dcfd77846193152aca1e
# Parent  273094759fdd91afc8f89d2bc6d3dfa48b8fabdc
Initial HIDPI support for SDL2.

What works
- creating a window with HIDPI enabled
- creating a fullscreen-desktop window with HIDPI enabled
- toggling between window and fullscreen-desktop
What does not work
- regular fullscreen mode fails to render things
- when popping out of fullscreen (mode switch) to windowed rendering is "off" until you move the window.
What is untested
- anything to do with the SDL Rendering API.

diff --git a/include/SDL_video.h b/include/SDL_video.h
--- a/include/SDL_video.h
+++ b/include/SDL_video.h
@@ -107,7 +107,8 @@
     SDL_WINDOW_INPUT_FOCUS = 0x00000200,        /**< window has input focus */
     SDL_WINDOW_MOUSE_FOCUS = 0x00000400,        /**< window has mouse focus */
     SDL_WINDOW_FULLSCREEN_DESKTOP = ( SDL_WINDOW_FULLSCREEN | 0x00001000 ),
-    SDL_WINDOW_FOREIGN = 0x00000800             /**< window not created by SDL */
+    SDL_WINDOW_FOREIGN = 0x00000800,            /**< window not created by SDL */
+    SDL_WINDOW_HIDPI = 0x0000002000             /**< request hidpi mode if supported */
 } SDL_WindowFlags;
 
 /**
@@ -540,6 +541,20 @@
  */
 extern DECLSPEC void SDLCALL SDL_GetWindowSize(SDL_Window * window, int *w,
                                                int *h);
+/**
+ * \brief Gets the scale factor of the current window.
+ *
+ * \param scale_x  Pointer to variable for storing the X scale, may be NULL
+ * \param scale_y  Pointer to variable for storing the Y scale, may be NULL
+ *
+ *
+ * \note This will always return 1.0f/1.0f unless on a display that supports
+ *       HiDPI Resolutions
+ *
+ * \sa SDL_WINDOW_HIDPI
+ */
+extern DECLSPEC void SDLCALL SDL_GetWindowScale(SDL_Window * window,
+                                                float *scale_x, float *scale_y);
 
 /**
  *  \brief Set the minimum size of a window's client area.
diff --git a/src/test/SDL_test_common.c b/src/test/SDL_test_common.c
--- a/src/test/SDL_test_common.c
+++ b/src/test/SDL_test_common.c
@@ -368,6 +368,10 @@
         state->window_flags |= SDL_WINDOW_INPUT_GRABBED;
         return 1;
     }
+    if (SDL_strcasecmp(argv[index], "--hidpi") == 0) {
+        state->window_flags |= SDL_WINDOW_HIDPI;
+        return 1;
+    }
     if (SDL_strcasecmp(argv[index], "--rate") == 0) {
         ++index;
         if (!argv[index]) {
diff --git a/src/video/SDL_sysvideo.h b/src/video/SDL_sysvideo.h
--- a/src/video/SDL_sysvideo.h
+++ b/src/video/SDL_sysvideo.h
@@ -184,6 +184,7 @@
     void (*SetWindowIcon) (_THIS, SDL_Window * window, SDL_Surface * icon);
     void (*SetWindowPosition) (_THIS, SDL_Window * window);
     void (*SetWindowSize) (_THIS, SDL_Window * window);
+    void (*GetWindowScale) (_THIS, SDL_Window * window, float * sx, float * sy);
     void (*SetWindowMinimumSize) (_THIS, SDL_Window * window);
     void (*SetWindowMaximumSize) (_THIS, SDL_Window * window);
     void (*ShowWindow) (_THIS, SDL_Window * window);
diff --git a/src/video/SDL_video.c b/src/video/SDL_video.c
--- a/src/video/SDL_video.c
+++ b/src/video/SDL_video.c
@@ -1152,7 +1152,7 @@
 }
 
 #define CREATE_FLAGS \
-    (SDL_WINDOW_OPENGL | SDL_WINDOW_BORDERLESS | SDL_WINDOW_RESIZABLE)
+    (SDL_WINDOW_OPENGL | SDL_WINDOW_BORDERLESS | SDL_WINDOW_RESIZABLE | SDL_WINDOW_HIDPI)
 
 static void
 SDL_FinishWindowCreation(SDL_Window *window, Uint32 flags)
@@ -1608,6 +1608,22 @@
 }
 
 void
+SDL_GetWindowScale(SDL_Window * window, float *scale_x, float *scale_y)
+{
+    float sx = 1.0f, sy = 1.0f;
+    CHECK_WINDOW_MAGIC(window, );
+    if (_this->GetWindowScale) {
+        _this->GetWindowScale(_this, window, &sx, &sy);
+    }
+    if (scale_x) {
+        *scale_x = sx;
+    }
+    if (scale_y) {
+        *scale_y = sy;
+    }
+}
+
+void
 SDL_SetWindowMinimumSize(SDL_Window * window, int min_w, int min_h)
 {
     CHECK_WINDOW_MAGIC(window, );
diff --git a/src/video/cocoa/SDL_cocoavideo.m b/src/video/cocoa/SDL_cocoavideo.m
--- a/src/video/cocoa/SDL_cocoavideo.m
+++ b/src/video/cocoa/SDL_cocoavideo.m
@@ -95,6 +95,7 @@
     device->SetWindowIcon = Cocoa_SetWindowIcon;
     device->SetWindowPosition = Cocoa_SetWindowPosition;
     device->SetWindowSize = Cocoa_SetWindowSize;
+    device->GetWindowScale = Cocoa_GetWindowScale;
     device->SetWindowMinimumSize = Cocoa_SetWindowMinimumSize;
     device->SetWindowMaximumSize = Cocoa_SetWindowMaximumSize;
     device->ShowWindow = Cocoa_ShowWindow;
diff --git a/src/video/cocoa/SDL_cocoawindow.h b/src/video/cocoa/SDL_cocoawindow.h
--- a/src/video/cocoa/SDL_cocoawindow.h
+++ b/src/video/cocoa/SDL_cocoawindow.h
@@ -98,6 +98,7 @@
 extern void Cocoa_SetWindowIcon(_THIS, SDL_Window * window, SDL_Surface * icon);
 extern void Cocoa_SetWindowPosition(_THIS, SDL_Window * window);
 extern void Cocoa_SetWindowSize(_THIS, SDL_Window * window);
+extern void Cocoa_GetWindowScale(_THIS, SDL_Window * window, float * sx, float * sy);
 extern void Cocoa_SetWindowMinimumSize(_THIS, SDL_Window * window);
 extern void Cocoa_SetWindowMaximumSize(_THIS, SDL_Window * window);
 extern void Cocoa_ShowWindow(_THIS, SDL_Window * window);
diff --git a/src/video/cocoa/SDL_cocoawindow.m b/src/video/cocoa/SDL_cocoawindow.m
--- a/src/video/cocoa/SDL_cocoawindow.m
+++ b/src/video/cocoa/SDL_cocoawindow.m
@@ -33,6 +33,12 @@
 #include "SDL_cocoashape.h"
 #include "SDL_cocoamouse.h"
 
+#if MAC_OS_X_VERSION_MIN_REQUIRED < 1070
+@interface NSView (OpenGLRetinaAdditions)
+- (NSRect)convertRectToBacking:(NSRect)aRect;
+- (void)setWantsBestResolutionOpenGLSurface:(BOOL)flag;
+@end
+#endif
 
 static Uint32 s_moveHack;
 
@@ -697,6 +703,15 @@
     rect = [nswindow contentRectForFrameRect:[nswindow frame]];
     NSView *contentView = [[SDLView alloc] initWithFrame:rect];
     [nswindow setContentView: contentView];
+
+    // DPI is only valid for explicit OpenGL right now
+    if ( (window->flags & (SDL_WINDOW_OPENGL | SDL_WINDOW_HIDPI)) == (SDL_WINDOW_OPENGL | SDL_WINDOW_HIDPI) )
+    {
+        if ([contentView respondsToSelector:@selector(setWantsBestResolutionOpenGLSurface:)]) {
+            [contentView setWantsBestResolutionOpenGLSurface:YES];
+        }
+    }
+
     [contentView release];
 
     [pool release];
@@ -805,6 +820,24 @@
 }
 
 void
+Cocoa_GetWindowScale(_THIS, SDL_Window * window, float * sx, float * sy)
+{
+    SDL_WindowData *windata = (SDL_WindowData *) window->driverdata;
+    NSWindow *nswindow = windata->nswindow;
+
+    NSView *view = [nswindow contentView];
+    if ((window->flags & SDL_WINDOW_HIDPI) && [view respondsToSelector:@selector(convertRectToBacking:)]) {
+        NSRect orig = [view bounds];
+        NSRect rect = [view convertRectToBacking:orig];
+        *sx = rect.size.width / orig.size.width;
+        *sy = rect.size.height / orig.size.height;
+    } else {
+        *sx = 1.0f;
+        *sy = 1.0f;
+    }
+}
+
+void
 Cocoa_SetWindowMinimumSize(_THIS, SDL_Window * window)
 {
     NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
diff --git a/test/testgl2.c b/test/testgl2.c
--- a/test/testgl2.c
+++ b/test/testgl2.c
@@ -180,6 +180,7 @@
     SDL_Event event;
     Uint32 then, now, frames;
     int status;
+    float sx, sy;
 
     /* Initialize parameters */
     fsaa = 0;
@@ -249,8 +250,11 @@
     }
 
     SDL_GetCurrentDisplayMode(0, &mode);
+    SDL_GetWindowScale(state->windows[0], &sx, &sy);
     printf("Screen BPP    : %d\n", SDL_BITSPERPIXEL(mode.format));
     printf("Swap Interval : %d\n", SDL_GL_GetSwapInterval());
+    printf("Window Size   : %d,%d\n", state->window_w, state->window_h);
+    printf("Back buffer   : %d,%d\n", (int)(state->window_w * sx), (int)(state->window_h * sy));
     printf("\n");
     printf("Vendor        : %s\n", glGetString(GL_VENDOR));
     printf("Renderer      : %s\n", glGetString(GL_RENDERER));
@@ -331,10 +335,17 @@
             SDLTest_CommonEvent(state, &event, &done);
         }
         for (i = 0; i < state->num_windows; ++i) {
+            static int prev_w  = 0, prev_h = 0;
             int w, h;
+            float sx, sy;
             SDL_GL_MakeCurrent(state->windows[i], context);
             SDL_GetWindowSize(state->windows[i], &w, &h);
-            glViewport(0, 0, w, h);
+            SDL_GetWindowScale(state->windows[i], &sx, &sy);
+            if (prev_h != (h * sy) || prev_w != (w * sx)) {
+                prev_h = h * sy; prev_w = w * sx;
+                printf("Changing resolution to (%d, %d) as scale (%f, %f)]\n", w, h, sx, sy);
+            }
+            glViewport(0, 0, w * sx, h * sy);
             Render();
             SDL_GL_SwapWindow(state->windows[i]);
         }