android自定义view仿照MIUI中音量控制效果

@Override
    protected void onDraw(Canvas canvas) {
        float cx = getMeasuredWidth() / 2;
        float cy = getMeasuredHeight() / 2;
        r1 = cx - w1 / 2;
        r2 = cx - w1 / 2 - w2 / 2;
        r3 = cx - w1 / 2 - w2;

        // 绘制外圆
        paint.setStrokeWidth(w1);
        paint.setColor(Color.parseColor("#454547"));
        canvas.drawCircle(cx, cy, r1, paint);

        // 绘制中间圆环
        paint.setColor(Color.parseColor("#747476"));
        paint.setStrokeWidth(w2);
        canvas.drawCircle(cx, cy, r2, paint);

        // 绘制内圆
        paint.setColor(Color.parseColor("#464648"));
        paint.setStyle(Style.FILL);
        canvas.drawCircle(cx, cy, r3, paint);

        // 绘制中间的图片
        canvas.drawBitmap(bitmap, cx - bitmap.getWidth() / 2,
                cx - bitmap.getHeight() / 2, paint);

        // 绘制文本
        paint.setColor(Color.WHITE);
        paint.setStrokeWidth(0);
        paint.setTextSize(40);
        float textWidth = paint.measureText("铃声"); // 测量字体宽度，我们需要根据字体的宽度设置在圆环中间

        canvas.drawText("铃声", cx - textWidth / 2, cx + bitmap.getHeight() / 2
                + 40, paint);

        // 绘制进度
        paint.setStyle(Style.STROKE);
        paint.setStrokeWidth(w2);
        paint.setColor(Color.WHITE);
        RectF oval = new RectF(cx - r2, cy - r2, cx + r2, cy + r2); // 用于定义的圆弧的形状和大小的界限
        canvas.drawArc(oval, 270, 360 * progress / 100, false, paint);

        super.onDraw(canvas);
    }

public class VolumnController {
    Toast t;
    VolumnView tv;

    Context context;

    public VolumnController(Context context) {
        this.context = context;
    }

    public void show(float progress) {
        if (t == null) {
            t = new Toast(context);
            View layout = LayoutInflater.from(context).inflate(R.layout.vv,
                    null);
            tv = (VolumnView) layout.findViewById(R.id.volumnView1);
            t.setView(layout);
            t.setGravity(Gravity.BOTTOM, 0, 100);
            t.setDuration(Toast.LENGTH_SHORT);
        }
        tv.setProgress(progress);
        t.show();
    }
}