Question

问题是我希望保留矩形的大小，同时它在画布中来回移动。这是myview.java代码：

public class MyView extends View {

    private int xMin = 0;
    private int xMax;
    private int yMin = 0;
    private int yMax;
    private float rectX =130;
    private float rectY =180;
    private float rectSpeedX = 5;
    private float rectSpeedY = 3;
    private RectF RectBounds;
    private Paint paint;

    public MyView(Context context) {
        super(context);
        RectBounds = new RectF();
        paint = new Paint();
    }
    @Override
    public void onDraw(Canvas canvas) {
        RectBounds.set(rectX, rectX, rectY, rectY);
        paint.setColor(Color.BLACK);
        paint.setStrokeWidth(3);
        canvas.drawRect(RectBounds,paint);
        paint.setStrokeWidth(0);
        paint.setColor(Color.CYAN);
        canvas.drawRect(RectBounds,paint);
        paint.setColor(Color.YELLOW);
        canvas.drawRect(RectBounds,paint);
        start();
        invalidate();
    }
    private void start() {
        rectX += rectSpeedX;
        rectY += rectSpeedY;
        if (rectX> xMax) {
            rectSpeedX = -rectSpeedX;
            rectX = xMax;
        } else if (rectX < xMin) {
            rectSpeedX = -rectSpeedX;
            rectX = xMin;
        }
        if (rectY > yMax) {
            rectSpeedY = -rectSpeedY;
            rectY = yMax;
        } else if (rectY  < yMin) {
            rectSpeedY = -rectSpeedY;
            rectY = yMin;
        }
    }
    @Override
    public void onSizeChanged(int w, int h, int oldW, int oldH) {
        xMax = w-1;
        yMax = h-1;
    }
}

此外，如果您有任何建议可以缩短我的代码。我会很高兴的。谢谢。

Answer 1

你可以使用类似的东西：

RectBounds.set(rectX, rectX + rectWidth, rectY, rectY + rectHeight);

你也不应该使用大写字母表示对象名称（RectBounds - ＆gt; rectBounds），或者对于这种特殊情况，你应该将它命名为'rect'，因为它是一个RectF。

如何设置我的矩形以在画布中弹跳时保持其大小？

1 个答案: