上面创建了红色的画笔,并希望画出来的矩形框是红色的,结果每次画出来都是 白色的, (背景是黑色的)无论我怎么修改画笔的颜色,请问要实现画出来的是 -created a red above the brush, and hope to be painted with the red rectangular box, the results of each are drawn to the white (black background) it is for me how to amend