public class FackMask extends View {

    private static final String TAG = "FackMask";
    private Paint paint;
    private Rect rect;
    private int left;
    private int top;
    private int right;
    private int bottom;
    private Canvas canvas;
    public FackMask(Context context){
        super
 
(context);
}

    public FackMask(Context context, @Nullable AttributeSet attrs) {
        this(context, attrs, 0);
}

    public FackMask(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
initPaint();
}


    /**
     * 外部呼叫的介面
* */
public void 
 
setRect(int left,int top,int right,int bottom){
        this.left=left;
        this.top=top;
        this.right=right;
        this.bottom=bottom;
Log.d(TAG, "setRect: 控制元件");
invalidate();//更新呼叫onDraw重新繪製
}



    private void initPaint(){
        paint=new Paint();
left=100;
top=100;
right=300;
bottom=300;
 
}



    @Override
protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
paint.setColor(Color.GREEN);
paint.setStyle(Paint.Style.STROKE);//設定空心
rect=new Rect(left,top,right,bottom);
canvas.drawRect(rect,paint);
}

}