cocoa: Fix VBE function Set Display Start

Register a dpy_gfx_setdata callback so that the Cocoa code
is notified whenever the screen start address changes.

Commit 1d3323d has a similar fix for the VNC UI.

Signed-off-by: Henry Harrington <henry.harrington@gmail.com>
Cc: qemu-stable@nongnu.org (1.3.x)
Signed-off-by: Andreas Färber <andreas.faerber@web.de>

ui/cocoa.m

@@ -265,6 +265,7 @@ static int cocoa_keycode_to_qemu(int keycode)
     BOOL isTabletEnabled;
 }
 - (void) resizeContentToWidth:(int)w height:(int)h displayState:(DisplayState *)ds;
+- (void) updateDataOffset:(DisplayState *)ds;
 - (void) grabMouse;
 - (void) ungrabMouse;
 - (void) toggleFullScreen:(id)sender;
@@ -429,6 +430,20 @@ QemuCocoaView *cocoaView;
     [self setFrame:NSMakeRect(cx, cy, cw, ch)];
 }
 
+- (void) updateDataOffset:(DisplayState *)ds
+{
+    COCOA_DEBUG("QemuCocoaView: UpdateDataOffset\n");
+
+    // update screenBuffer
+    if (dataProviderRef) {
+        CGDataProviderRelease(dataProviderRef);
+    }
+
+    size_t size = ds_get_width(ds) * 4 * ds_get_height(ds);
+    dataProviderRef = CGDataProviderCreateWithData(NULL, ds_get_data(ds),
+                                                   size, NULL);
+}
+
 - (void) toggleFullScreen:(id)sender
 {
     COCOA_DEBUG("QemuCocoaView: toggleFullScreen\n");
@@ -1004,6 +1019,11 @@ static void cocoa_refresh(DisplayState *ds)
     vga_hw_update();
 }
 
+static void cocoa_setdata(DisplayState *ds)
+{
+    [cocoaView updateDataOffset:ds];
+}
+
 static void cocoa_cleanup(void)
 {
     COCOA_DEBUG("qemu_cocoa: cocoa_cleanup\n");
@@ -1020,6 +1040,7 @@ void cocoa_display_init(DisplayState *ds, int full_screen)
     dcl->dpy_gfx_update = cocoa_update;
     dcl->dpy_gfx_resize = cocoa_resize;
     dcl->dpy_refresh = cocoa_refresh;
+    dcl->dpy_gfx_setdata = cocoa_setdata;
 
 	register_displaychangelistener(ds, dcl);