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src/glx/apple/apple_xgl_api_read.c

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+/*
+ Copyright (c) 2008-2011 Apple Inc.
+ 
+ Permission is hereby granted, free of charge, to any person
+ obtaining a copy of this software and associated documentation files
+ (the "Software"), to deal in the Software without restriction,
+ including without limitation the rights to use, copy, modify, merge,
+ publish, distribute, sublicense, and/or sell copies of the Software,
+ and to permit persons to whom the Software is furnished to do so,
+ subject to the following conditions:
+ 
+ The above copyright notice and this permission notice shall be
+ included in all copies or substantial portions of the Software.
+ 
+ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ NONINFRINGEMENT.  IN NO EVENT SHALL THE ABOVE LISTED COPYRIGHT
+ HOLDER(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ DEALINGS IN THE SOFTWARE.
+ 
+ Except as contained in this notice, the name(s) of the above
+ copyright holders shall not be used in advertising or otherwise to
+ promote the sale, use or other dealings in this Software without
+ prior written authorization.
+*/
+
+/*
+ * This file works with the glXMakeContextCurrent readable drawable. 
+ *
+ * The way it works is by swapping the currentDrawable for the currentReadable
+ * drawable if they are different.
+ */
+#include <stdbool.h>
+#include "glxclient.h"
+#include "apple_glx_context.h"
+#include "apple_xgl_api.h"
+#include "glapi.h"
+#include "dispatch.h"
+
+extern struct _glapi_table * __ogl_framework_api;
+
+struct apple_xgl_saved_state
+{
+   bool swapped;
+};
+
+static void
+SetRead(struct apple_xgl_saved_state *saved)
+{
+   struct glx_context *gc = __glXGetCurrentContext();
+
+   /*
+    * By default indicate that the state was not swapped, so that UnsetRead
+    * functions correctly.
+    */
+   saved->swapped = false;
+
+   /* 
+    * If the readable drawable isn't the same as the drawable then 
+    * the user has requested a readable drawable with glXMakeContextCurrent().
+    * We emulate this behavior by switching the current drawable.
+    */
+   if (None != gc->currentReadable
+       && gc->currentReadable != gc->currentDrawable) {
+      Display *dpy = glXGetCurrentDisplay();
+
+      saved->swapped = true;
+
+      if (apple_glx_make_current_context(dpy, gc->driContext, gc->driContext,
+                                         gc->currentReadable)) {
+         /* An error occurred, so try to restore the old context state. */
+         (void) apple_glx_make_current_context(dpy, gc->driContext, gc->driContext,
+                                               gc->currentDrawable);
+         saved->swapped = false;
+      }
+   }
+}
+
+static void
+UnsetRead(struct apple_xgl_saved_state *saved)
+{
+   if (saved->swapped) {
+      struct glx_context *gc = __glXGetCurrentContext();
+      Display *dpy = glXGetCurrentDisplay();
+
+      if (apple_glx_make_current_context(dpy, gc->driContext, gc->driContext,
+                                         gc->currentDrawable)) {
+         /*
+          * An error occurred restoring the drawable.
+          * It's unclear what to do about that. 
+          */
+      }
+   }
+}
+
+void
+__applegl_glReadPixels(GLint x, GLint y, GLsizei width, GLsizei height,
+             GLenum format, GLenum type, void *pixels)
+{
+   struct apple_xgl_saved_state saved;
+
+   SetRead(&saved);
+   CALL_ReadPixels(__ogl_framework_api, (x, y, width, height, format, type, pixels));
+
+   UnsetRead(&saved);
+}
+
+void
+__applegl_glCopyPixels(GLint x, GLint y, GLsizei width, GLsizei height, GLenum type)
+{
+   struct apple_xgl_saved_state saved;
+
+   SetRead(&saved);
+
+   CALL_CopyPixels(__ogl_framework_api, (x, y, width, height, type));
+
+   UnsetRead(&saved);
+}