Allow frame callback to be enabled/disabled

Since per-frame readback is slow and clients don't need it on all the
time, this change allows the callback to be registered after
initialization, and allows it to be disabled later.

Change-Id: Ic73d4515d302a0981ee0c80b9e6f9ba5c84b82ae

1 files changed, 35 insertions, 34 deletions

diff --git a/emulator/opengl/host/include/libOpenglRender/render_api.h b/emulator/opengl/host/include/libOpenglRender/render_api.h
index ebb02eb..4fe54f4 100644
--- a/emulator/opengl/host/include/libOpenglRender/render_api.h
+++ b/emulator/opengl/host/include/libOpenglRender/render_api.h
@@ -41,38 +41,6 @@ extern "C" {
 	ret name args
 #endif
 
-/* If a function with this signature is passed to initOpenGLRenderer(),
- * it will be called by the renderer just before each new frame is displayed,
- * providing a copy of the framebuffer contents.
- *
- * The callback will be called from one of the renderer's threads, so will
- * probably need synchronization on any data structures it modifies. The
- * pixels buffer may be overwritten as soon as the callback returns; if it needs
- * the pixels afterwards it must copy them.
- *
- * The pixels buffer is intentionally not const: the callback may modify the
- * data without copying to another buffer if it wants, e.g. in-place RGBA to RGB
- * conversion, or in-place y-inversion.
- *
- * Parameters are:
- *   context        The pointer optionally provided when the callback was
- *                  registered. The client can use this to pass whatever
- *                  information it wants to the callback.
- *   width, height  Dimensions of the image, in pixels. Rows are tightly packed;
- *                  there is no inter-row padding.
- *   ydir           Indicates row order: 1 means top-to-bottom order, -1 means
- *                  bottom-to-top order.
- *   format, type   Format and type GL enums, as used in glTexImage2D() or
- *                  glReadPixels(), describing the pixel format.
- *   pixels         The framebuffer image.
- *
- * In the first implementation, ydir is always -1 (bottom to top), format and
- * type are always GL_RGBA and GL_UNSIGNED_BYTE, and the width and height will
- * always be the same as the ones passed to initOpenGLRenderer().
- */
-typedef void (*OnPostFn)(void* context, int width, int height, int ydir,
-                         int format, int type, unsigned char* pixels);
-
 /* initLibrary - initialize the library and tries to load the corresponding
  *     GLES translator libraries. This function must be called before anything
  *     else to ensure that everything works. If it returns an error, then
@@ -98,8 +66,7 @@ DECL(int, setStreamMode, (int mode));
  * This function is *NOT* thread safe and should be called first
  * to initialize the renderer after initLibrary().
  */
-DECL(int, initOpenGLRenderer, (int width, int height, int portNum,
-		OnPostFn onPost, void* onPostContext));
+DECL(int, initOpenGLRenderer, (int width, int height, int portNum));
 
 /* getHardwareStrings - describe the GPU hardware and driver.
  *    The underlying GL's vendor/renderer/version strings are returned to the
@@ -108,6 +75,40 @@ DECL(int, initOpenGLRenderer, (int width, int height, int portNum,
 DECL(void, getHardwareStrings, (const char** vendor, const char** renderer,
 		const char** version));
 
+/* A per-frame callback can be registered with setPostCallback(); to remove it
+ * pass NULL for both parameters. While a callback is registered, the renderer
+ * will call it just before each new frame is displayed, providing a copy of
+ * the framebuffer contents.
+ *
+ * The callback will be called from one of the renderer's threads, so will
+ * probably need synchronization on any data structures it modifies. The
+ * pixels buffer may be overwritten as soon as the callback returns; if it
+ * needs the pixels afterwards it must copy them.
+ *
+ * The pixels buffer is intentionally not const: the callback may modify the
+ * data without copying to another buffer if it wants, e.g. in-place RGBA to
+ * RGB conversion, or in-place y-inversion.
+ *
+ * Parameters are:
+ *   context        The pointer optionally provided when the callback was
+ *                  registered. The client can use this to pass whatever
+ *                  information it wants to the callback.
+ *   width, height  Dimensions of the image, in pixels. Rows are tightly
+ *                  packed; there is no inter-row padding.
+ *   ydir           Indicates row order: 1 means top-to-bottom order, -1 means
+ *                  bottom-to-top order.
+ *   format, type   Format and type GL enums, as used in glTexImage2D() or
+ *                  glReadPixels(), describing the pixel format.
+ *   pixels         The framebuffer image.
+ *
+ * In the first implementation, ydir is always -1 (bottom to top), format and
+ * type are always GL_RGBA and GL_UNSIGNED_BYTE, and the width and height will
+ * always be the same as the ones passed to initOpenGLRenderer().
+ */
+typedef void (*OnPostFn)(void* context, int width, int height, int ydir,
+                         int format, int type, unsigned char* pixels);
+DECL(void, setPostCallback, (OnPostFn onPost, void* onPostContext));
+
 /* createOpenGLSubwindow -
  *     Create a native subwindow which is a child of 'window'
  *     to be used for framebuffer display.