code: func SetClipRect(x, y, w, h int) {
  	if x < 0 {
  		x = 0
  	}
  	if y < 0 {
  		y = 0
  	}
  	if x+w > canvas.width {
  		w = canvas.width - x
  	}
  	if y+h > canvas.height {
  		h = canvas.height - h
  	}
  
  	canvas.clipX = x
  	canvas.clipY = y
  	canvas.clipW = w
  	canvas.clipH = h
  }
docs: // SetClipRect defines a new clipping rect. Maybe useful with PopClip and
  // PushClip functions