RoundedImageView源码解析（二）RoundedDrawable解析

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VIP免费原创最新推荐文章于 2026-07-23 08:30:00 发布 1.8k 阅读 AI 写同款· GEO 优化 ›

RoundedImageView源码解析（三）RoundedImageView解析现在开始RoundedImageView的源码解析了，之前的RoundedDrawable就是为RoundedImageView的实现做铺垫。 RoundedDrawable的作用主要是把Drawable转化为圆角的Drawable. 如果不清楚RoundedDrawable的话，可以参考我的前一篇博客http://blog.youkuaiyun.com/wangdong20/article/details 阅读详情

RoundedImageView类库的核心内容就在于RoundedDrawable，所以今天就来分析RoundedDrawable的源码。

不了解RoundedImageView类库的朋友可以看看上一篇博客http://blog.youkuaiyun.com/wangdong20/article/details/50705051

首先看构造方法：

public RoundedDrawable(Bitmap bitmap) {
    mBitmap = bitmap;

    mBitmapWidth = bitmap.getWidth();
    mBitmapHeight = bitmap.getHeight();
    mBitmapRect.set(0, 0, mBitmapWidth, mBitmapHeight);

    mBitmapPaint = new Paint();
    mBitmapPaint.setStyle(Paint.Style.FILL);
    mBitmapPaint.setAntiAlias(true);

    mBorderPaint = new Paint();
    mBorderPaint.setStyle(Paint.Style.STROKE);
    mBorderPaint.setAntiAlias(true);
    mBorderPaint.setColor(mBorderColor.getColorForState(getState(), DEFAULT_BORDER_COLOR));
    mBorderPaint.setStrokeWidth(mBorderWidth);
  }

我们可以看到RoundedDrawable的构造方法里传的参数是Bitmap，其实后面会提到，RoundedDrawable可以把Drawable转化成Bitmap然后进行绘制，里面用到了2个Paint，分别是mBitmapPaint和mBorderPaint。一个用于绘制内部具体内容，一个用于绘制边框。

public static Drawable fromDrawable(Drawable drawable) {
    if (drawable != null) {
      if (drawable instanceof RoundedDrawable) {
        // just return if it's already a RoundedDrawable
        return drawable;
      } else if (drawable instanceof LayerDrawable) {
        LayerDrawable ld = (LayerDrawable) drawable;
        int num = ld.getNumberOfLayers();

        // loop through layers to and change to RoundedDrawables if possible
        for (int i = 0; i < num; i++) {
          Drawable d = ld.getDrawable(i);
          ld.setDrawableByLayerId(ld.getId(i), fromDrawable(d));
        }