+ * @brief Possible composition types for a given window
+ * @since 2.0.0
+ */
+typedef enum {
+
+ /** The composition type for an invisible window. The value by default.
+ *
+ * The backend ignores windows of this type.
+ */
+ TDM_HWC_WIN_COMPOSITION_NONE = 0,
+
+ /** The compostion type for an window to be compsoited by the client.
+ *
+ * When the client sets this composition type,
+ * the backend MUST NOT modify this composition type into other types.
+ *
+ * When the backend changes TDM_HWC_WIN_COMPOSITION_DEVICE or TDM_HWC_WIN_COMPOSITION_CURSOR
+ * to this composition type at the time of tdm_hwc_validate and
+ * tdm_hwc_get_changed_composition_types,
+ * the client has to composite this window with gl or other drawing operations.
+ */
+ TDM_HWC_WIN_COMPOSITION_CLIENT = 1,
+
+ /** The compostion type for an window to be set to the hw overlay.
+ *
+ * The client sets this composition type to the visible windows before requesting
+ * the tdm_hwc_validate.
+ * Nomally, the backend leave it if the backend sets the window to the hw overlay.
+ * If the backend does not set the window to the hw overlay at the time of
+ * tdm_hwc_validate, the backend changes the composition type of the window into
+ * TDM_HWC_WIN_COMPOSITION_CLIENT.
+ */
+ TDM_HWC_WIN_COMPOSITION_DEVICE = 3,
+
+ /** The compostion type for an window to be set to the cursor hw overlay.
+ *
+ * The client sets this composition type to the cursor window before requesting
+ * the tdm_hwc_validate.
+ * If the backend does not support the cursor hw overlay, the backend can change
+ * the comopsition type into the TDM_HWC_WIN_COMPOSITION_CLIENT.
+ */
+ TDM_HWC_WIN_COMPOSITION_CURSOR = 4,
+
+ /** The compostion type for an window to be set to the video hw overlay.
+ *
+ * The client sets this composition type to the video window before requesting
+ * the tdm_hwc_validate.
+ * If the backend does not support the video hw overlay, the backend can change
+ * the comopsition type into the TDM_HWC_WIN_COMPOSITION_CLIENT.
+ * Normally, this VIDEO window displays under the primary hw overlayer of the output.
+ */
+ TDM_HWC_WIN_COMPOSITION_VIDEO = 5,
+} tdm_hwc_window_composition;
+
+typedef enum {
+ TDM_HWC_WIN_CONSTRAINT_NONE = 0,
+ /** If the client needs to render to a specific buffer for compositing
+ * with TDM_HWC_WIN_COMPOSITION_DEVICE, the backend needs to set
+ * TDM_HWC_WIN_CONSTRAINT_BUFFER_QUEUE to hwc_window until the hwc_window is not
+ * TDM_HWC_WIN_COMPOSITION_DEVICE. The client gets the tbm_surface_queue_h through
+ * the tdm_hwc_window_aquire_buffer_queue. It will render the frames on
+ * the buffers which gets from the tbm_surface_queue_h.
+ */
+ TDM_HWC_WIN_CONSTRAINT_BUFFER_QUEUE = (1 << 0),
+} tdm_hwc_window_constraint;
+
+/**