java - 试图在圆周上绘制位图，在实现中找到一些偏移量

Question

我有这门课:

public class MockDraw extends View {

    private Paint mPaint;
    public static float angle = 0f;
    private int width;
    private int height;
    Context ctx;
    Bitmap icon;
    PointF pf;

    public MockDraw(Context ctx) {
        super(ctx);
        this.ctx = ctx;
        setFocusable(true);
        mPaint = new Paint();
        this.mPaint.setAntiAlias(true);
        this.mPaint.setStrokeWidth(4f);
        this.mPaint.setColor(Color.WHITE);
        this.mPaint.setStyle(Paint.Style.STROKE);
        this.mPaint.setStrokeJoin(Paint.Join.ROUND);

        icon = BitmapFactory.decodeResource(ctx.getResources(), R.drawable.ic_action_send_now);
    }


    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        this.width = w;
        this.height = h;

        float centerX = (float) width / 2;
        float centerY = (float) height / 2;

        pf = new PointF(centerX, centerY);
        super.onSizeChanged(w, h, oldw, oldh);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        canvas.drawColor(Color.BLACK);


        for (int i = 0; i <= 360; i += 45) {
            PointF px = getPosition(pf, 400, i);

            //   canvas.drawPoint(centerX, centerY, mPaint);
            canvas.drawPoint(px.x, px.y, mPaint);
            canvas.drawBitmap(icon, px.x, px.y, mPaint);

        }

    }

    private PointF getPosition(PointF center, float radius, float angle) {

        return new PointF((float) (center.x + radius * Math.cos(Math.toRadians(angle))),
                (float) (center.y + radius * Math.sin(Math.toRadians(angle))));
    }

    //  canvas.drawText("TEST", centerX, centerY, mPaint);


}

这是匆忙的代码，我打算稍后清理这些代码以进行内存优化和逻辑标准。

我类的目的是找到屏幕的中心，计算出一定半径的圆周上45度角的点。

这对 Points 工作正常，但是当我在这些点上绘制位图时，我得到了一点偏移。我附上了一个例子:

Answer 1

我认为如果您将位图中心与绘制的点对齐，那么它会给出正确的结果。

canvas.drawBitmap(icon, px.x, px.y, mPaint);

改为

if(px.x-icon.getWidth()/2>0&&px.y-icon.getHeight()/2>0)
canvas.drawBitmap(icon, px.x-icon.getWidth()/2, px.y-icon.getHeight()/2, mPaint);