如何在动画动态壁纸前显示图像

In my live wallpaper, I am drawing bitmaps on a canvas which cycle every frame to create an animation. I want to show pop up notifications on the screen, so that they appear in front of the background animated wallpaper. I am not using any layouts for the canvas. So if I were to use layouts, how can i stack the background canvas and foreground pop up image?In my live wallpaper, I am drawing bitmaps on a