如何绘制箭头（在 Android 中）？

我对 Android 相当陌生，一直在尝试 Canvas。我正在尝试绘制箭头，但我只是运气好地绘制了轴，所有箭头都不起作用。

我搜索了一下，找到了一个Java示例，但是Android没有GeneralPath or AffineTransform.

现在我的代码如下所示（箭头看起来一点也不像箭头）：

public class DrawableView extends View {
    Context mContext;
    private int centerX;
    private int centerY;
    private int radius;
    private double arrLength;
    private double arrHeading;
    private int margin = 10;

    public DrawableView(Context context) {
        super(context);
        mContext = context;
    }


    @Override
    protected void onDraw(Canvas canvas) {
        //Paint Background
        Paint background = new Paint();
        background.setColor(getResources().getColor(R.color.background);
        canvas.drawRect(0, 0, getWidth(), getHeight(), background);

        //Set vars for Arrow Paint
        Paint paint = new Paint();
        paint.setColor(getResources().getColor(R.color.arrowColor);
        centerX = getWidth() / 2;
        centerY = getHeight() / 2;
        arrLength = radius - 10;

        if(centerX < centerY)
            radius = centerX - margin;
        else 
            radius = centerY - margin;

        //Draw Shaft
        int[] xy = findArrowPos(arrLength, arrHeading);
        canvas.drawLine(centerX, centerY, xy[0], xy[1], paint);

        //Draw ArrowHead
            //This is where I'm confused

    }

    private int[] findArrowPos(double length, double angle) {
        int[] points = new int[2];
        double theta = Math.toRadians(angle);
        points[0] = centerX + (int) (length * Math.cos(theta));
        points[1] = centerY + (int) (length * Math.sin(theta));
        return points;
    }
}

我查看了以下线程以获取指导：
* http://www.java-forums.org/awt-swing/6241-how-u-rotate-arrow-mark-line-moves-accordingly.html http://www.java-forums.org/awt-swing/6241-how-u-rotate-arrow-mark-line-moves-accordingly.html
* 如何在Java中绘制有向箭头线？ https://stackoverflow.com/questions/2027613/how-to-draw-a-directed-arrow-line-in-java

如何使用“Path myPath = new Path();”您可以在其中给出 x 和 y 位置，以使用线条创建三角形并填充它。您可以阅读相关内容，这是我从某处获取的示例。

// create and draw triangles
// use a Path object to store the 3 line segments
// use .offset to draw in many locations
// note: this triangle is not centered at 0,0
paint.setStyle(Paint.Style.STROKE);
paint.setStrokeWidth(2);
paint.setColor(Color.RED);
Path path = new Path();
path.moveTo(0, -10);
path.lineTo(5, 0);
path.lineTo(-5, 0);
path.close();
path.offset(10, 40);
canvas.drawPath(path, paint);
path.offset(50, 100);
canvas.drawPath(path, paint);
// offset is cumlative
// next draw displaces 50,100 from previous
path.offset(50, 100);
canvas.drawPath(path, paint);