如何在圆弧的末端画一条线？

Question

How do I draw a line at the end of an arc like so?

Here is the code I'm currently using to draw the arc

    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        setMeasuredDimension(widthMeasureSpec, heightMeasureSpec);
        canvasWidth = MeasureSpec.getSize(widthMeasureSpec);
        canvasHeight = MeasureSpec.getSize(heightMeasureSpec);
        padding = strokeWidth * 0.9f;
        arcAngle = 360 * 0.8f;
        rectF.set(padding, padding, canvasWidth - padding, canvasHeight - padding);
        arcRadius = (canvasWidth - padding) / 2f;
        arcBottomHeight = arcRadius * (float) (1 - Math.cos(angle / 180 * Math.PI));
    }

protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        float startAngle = 270 - arcAngle / 2f;
        float finishedSweepAngle = progress / (float) getMax() * arcAngle;
        float finishedStartAngle = startAngle;

        canvas.drawArc(rectF, startAngle, arcAngle, false, unfinishedPaint);
        canvas.drawArc(rectF, finishedStartAngle, finishedSweepAngle, false, finishedPaint);
}

This draws 2 arcs on top of each other, with the colored arc (finishedPaint) representing the progress.

I want to use canvas.drawLine() to draw the line at the end of the arc, but am unsure how to get the coordinates to specify the start and stop coordinates of the line.

Answer 1

Use trig. You know the radius of the arc and the angle it ends at. The x is radius*sin(endangle)+xcenter , the y is radius*cos(endangle)+ycenter . Then draw the line at that same angle where that lies.