Android Developer Documentation

• onSizeChanged()
• onDraw()

Exercise

In this exercise you are going to override onDraw().

1. Override onDraw() and draw the contents of the cached extraBitmap on the canvas associated with the view. The drawBitmap() Canvas method comes in several versions. In this code, you provide the bitmap, the x and y coordinates (in pixels) of the top left corner, and null for the Paint, as you'll set that later.

override fun onDraw(canvas: Canvas) {
   super.onDraw(canvas)
canvas.drawBitmap(extraBitmap, 0f, 0f, null)
}

Note: The 2D coordinate system used for drawing on a Canvas is in pixels, and the origin (0,0) is at the top left corner of the Canvas.