+ void draw_item(item&& item, \r
+ safe_ptr<device_buffer>& draw_buffer, \r
+ std::shared_ptr<device_buffer>& local_key_buffer, \r
+ std::shared_ptr<device_buffer>& layer_key_buffer)\r
+ { \r
+ draw_params draw_params;\r
+ draw_params.pix_desc = std::move(item.pix_desc);\r
+ draw_params.textures = std::move(item.textures);\r
+ draw_params.transform = std::move(item.transform);\r
+ draw_params.blend_mode = blend_mode::normal;\r
+\r
+ if(item.transform.is_key)\r
+ {\r
+ local_key_buffer = local_key_buffer ? local_key_buffer : create_device_buffer(1);\r
+\r
+ draw_params.background = local_key_buffer;\r
+ draw_params.local_key = nullptr;\r
+ draw_params.layer_key = nullptr;\r
+\r
+ kernel_.draw(channel_.ogl(), std::move(draw_params));\r
+ }\r
+ else\r
+ {\r
+ draw_params.background = draw_buffer;\r
+ draw_params.local_key = std::move(local_key_buffer);\r
+ draw_params.layer_key = layer_key_buffer;\r
+\r
+ kernel_.draw(channel_.ogl(), std::move(draw_params));\r
+ } \r
+ }\r
+ \r
+ safe_ptr<device_buffer> create_device_buffer(size_t stride)\r
+ {\r
+ auto buffer = channel_.ogl().create_device_buffer(channel_.get_format_desc().width, channel_.get_format_desc().height, stride);\r
+ channel_.ogl().clear(*buffer);\r
+ return buffer;\r
+ }\r
+};\r
+ \r
+struct image_mixer::implementation : boost::noncopyable\r
+{ \r
+ ogl_device& ogl_;\r
+ image_renderer renderer_;\r
+ std::vector<frame_transform> transform_stack_;\r
+ std::vector<layer> layers_; // layer/stream/items\r
+public:\r
+ implementation(video_channel_context& video_channel) \r
+ : ogl_(video_channel.ogl())\r
+ , renderer_(video_channel)\r
+ , transform_stack_(1) \r