add icons to taskbar control buttons

backend/windows/taskbar_buttons.h

@@ -6,8 +6,17 @@ extern "C" {
 
 typedef void (*ThumbnailCallback)(int buttonId);
 
+// sets the icons that will be used for the buttons.
+// the arguments are pointers to BGRA pixel data, and the dimensions (w, h) of all 4 images.
+int initialize_taskbar_icons(const void *bgraPrev, const void *bgraNext, const void *bgraPlay, const void *bgraPause, int width, int height);
+
+// adds the buttons to the window and registers the given callback to receive the button press events.
 int initialize_taskbar_buttons(void *hwndPtr, ThumbnailCallback cb);
 
+// sets whether the player is playing. controls which icon/tooltip the center button uses.
+// safe to call from any thread
+int set_is_playing(int playing);
+
 #ifdef __cplusplus
 }
 #endif