DefaultZoomableController.java 文件源码

/**
 * Limits the translation so that there are no empty spaces on the sides if possible.
 *
 * <p> The image is attempted to be centered within the view bounds if the transformed image is
 * smaller. There will be no empty spaces within the view bounds if the transformed image is
 * bigger. This applies to each dimension (horizontal and vertical) independently.
 *
 * @param limitTypes whether to limit translation along the specific axis.
 * @return whether limiting has been applied or not
 */
private boolean limitTranslation(Matrix transform, @LimitFlag int limitTypes) {
  if (!shouldLimit(limitTypes, LIMIT_TRANSLATION_X | LIMIT_TRANSLATION_Y)) {
    return false;
  }
  RectF b = mTempRect;
  b.set(mImageBounds);
  transform.mapRect(b);
  float offsetLeft = shouldLimit(limitTypes, LIMIT_TRANSLATION_X) ?
      getOffset(b.left, b.right, mViewBounds.left, mViewBounds.right, mImageBounds.centerX()) : 0;
  float offsetTop = shouldLimit(limitTypes, LIMIT_TRANSLATION_Y) ?
      getOffset(b.top, b.bottom, mViewBounds.top, mViewBounds.bottom, mImageBounds.centerY()) : 0;
  if (offsetLeft != 0 || offsetTop != 0) {
    transform.postTranslate(offsetLeft, offsetTop);
    return true;
  }
  return false;
}