Question

我有一个自定义视图，我画一个弧。现在我还需要绘制一条连接中心和圆周的线并且应该正好在弧的中间。

现在我知道android画布中绘制线的代码非常简单

但它不涉及角度，并且弧总是使用角度来绘制自己。

所以我可以在与弧相同的方向画线吗？

我在这里清楚还是需要解释更多？

请帮忙。

Answer 1

计算起点和终点。

private class MView extends View {
    private Paint mPaint;
    private RectF mRect;
    private int mCenterX = 150;
    private int mCenterY = 150;

    public MView(Context context) {
        super(context);
        mPaint = new Paint();
        mPaint.setColor(Color.BLACK);
        mPaint.setStyle(Style.STROKE);
        mRect = new RectF(0, 0, mCenterX * 2, mCenterY * 2);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        float startAngle = 30;
        float sweepAngle = 60;

        canvas.drawArc(mRect, startAngle, sweepAngle, true, mPaint);
        float startX = mCenterX;
        float startY = mCenterY;
        float radius = mCenterX;
        float angle = (float) ((startAngle + sweepAngle / 2) * Math.PI / 180);
        float stopX = (float) (startX + radius * Math.cos(angle));
        float stopY = (float) (startY + radius * Math.sin(angle));

        canvas.drawLine(startX, startY, stopX, stopY, mPaint);
    }

}

Answer 2

以下是基于以上答案的最终结果：

    for (int i = 0; i < numOfDividing; i++) {
        angle = i * (360 / numOfDividing);

        Point aPoint = new Point(
                (int) (x0 + (radius) * Math.cos(Math.toRadians(angle))),
                (int) (y0 + (radius) * Math.sin(Math.toRadians(angle)))
        );
        //Timber.d("Point %d : %d, %d", i, aPoint.x, aPoint.y);
        points.add(aPoint);
    }

如何在圆弧中绘制一条直线，将中心与圆周连接起来

2 个答案: