4.自定义view-进度条控件

1.效果

2.实现原理

画圆，画圆弧，画文字

外部控制进度，通过invalidate()方法更新

核心代码：

@Override
    protected void onDraw(Canvas canvas) {
        //super.onDraw(canvas);
        //1.画下面的圆
        int center = getWidth() / 2;
        int radius = center - mLineWidth / 2;

        canvas.drawCircle(center, center, radius, mBelowPaint);

        //2.画上面的圆弧
        RectF rectF = new RectF(mLineWidth / 2, mLineWidth / 2, getWidth() - mLineWidth / 2, getHeight() - mLineWidth / 2);
        canvas.drawArc(rectF, 0, mProcess * 360, false, mAbovePaint);

        //3.画中间的文字
        String text = (int) (mProcess * 100) + "%";
        Rect rect = new Rect();
        mTextPaint.getTextBounds(text, 0, text.length(), rect);
        int x = getWidth() / 2 - rect.width() / 2;
        Paint.FontMetricsInt fontMetrics = mTextPaint.getFontMetricsInt();

        int dy = (fontMetrics.bottom - fontMetrics.top) / 2 - fontMetrics.bottom;
        int baseLine = getHeight() / 2 + dy;

        canvas.drawText(text, x, baseLine, mTextPaint);

    }

源码地址