Android. How to paint all area around of rectangle?

Question

I have custom view and inside onDraw I need to draw in canvas rectangle. I have RectF with all coordinates. And now I need to paint the entire area around the rectangle in a different color. Is it possible to do this using RectF ?

Please help me.

Answer 1

To color red the outside of a 400 pixel by 400 pixel rectangle in the center of a view you can do the following in onDraw():

val canvasCenter = Point(canvas.width / 2, canvas.height / 2)
val r = Rect(
    canvasCenter.x - 200,
    canvasCenter.y - 200,
    canvasCenter.x + 200,
    canvasCenter.y + 200,
)
canvas.clipOutRect(r)
canvas.drawColor(Color.RED)

This code assumes that the view is at least 400px by 400px.

See clipRect.