FloatingActionButtonImpl.java 文件源码

private void calculateImageMatrixFromScale(float scale, Matrix matrix) {
  matrix.reset();

  Drawable drawable = view.getDrawable();
  if (drawable != null && maxImageSize != 0) {
    // First make sure our image respects mMaxImageSize.
    RectF drawableBounds = tmpRectF1;
    RectF imageBounds = tmpRectF2;
    drawableBounds.set(0, 0, drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight());
    imageBounds.set(0, 0, maxImageSize, maxImageSize);
    matrix.setRectToRect(drawableBounds, imageBounds, ScaleToFit.CENTER);

    // Then scale it as requested.
    matrix.postScale(scale, scale, maxImageSize / 2f, maxImageSize / 2f);
  }
}