How to use

setMaxScale

method

in

com.davemorrissey.labs.subscaleview.SubsamplingScaleImageView

/**
 * This is a screen density aware alternative to {@link #setMaxScale(float)}; it allows you to express the maximum
 * allowed scale in terms of the minimum pixel density. This avoids the problem of 1:1 scale still being
 * too small on a high density screen. A sensible starting point is 160 - the default used by this view.
 * @param dpi Source image pixel density at maximum zoom.
 */
public final void setMinimumDpi(int dpi) {
  DisplayMetrics metrics = getResources().getDisplayMetrics();
  float averageDpi = (metrics.xdpi + metrics.ydpi)/2;
  setMaxScale(averageDpi/dpi);
}

  mImageView.setMaxScale(Math.max(defaultMaxScale, maxScale * 1.2F));
} else {

  view.setMinimumDpi(50);
} else {
  view.setMaxScale(2F);

/**
 * This is a screen density aware alternative to {@link #setMaxScale(float)}; it allows you to express the maximum
 * allowed scale in terms of the minimum pixel density. This avoids the problem of 1:1 scale still being
 * too small on a high density screen. A sensible starting point is 160 - the default used by this view.
 * @param dpi Source image pixel density at maximum zoom.
 */
public final void setMinimumDpi(int dpi) {
  DisplayMetrics metrics = getResources().getDisplayMetrics();
  float averageDpi = (metrics.xdpi + metrics.ydpi)/2;
  setMaxScale(averageDpi/dpi);
}

private SubsamplingScaleImageView getLongImageView(ImageSource imageSource, File file, int orientation, float hScale) {
  SubsamplingScaleImageView imageView = new SubsamplingScaleImageView(this);
  if (orientation == 1) {//纵向图
    imageView.setMinimumScaleType(SubsamplingScaleImageView.SCALE_TYPE_CENTER_CROP);
    imageView.setImage(imageSource, new ImageViewState(0, new PointF(0, 0), SubsamplingScaleImageView.ORIENTATION_0));
  } else {//横向长图
    if (file != null) {
      //因为这里展示的是原图，不是经过fresco压缩的bitmap，这里拿到图片的原始宽高，从新计算最大缩放比
      hScale = screenHeight / BitmapUtil.getImageSize(file.getAbsolutePath())[1];
    }
    imageView.setMaxScale(hScale);
    imageView.setImage(imageSource);
  }
  imageView.setOnClickListener(onClickListener);
  //图片下载完成并且开启图片保存才给长按保存
  imageView.setOnLongClickListener(this);
  return imageView;
}

/**
 * 加载超长图
 */
private SubsamplingScaleImageView loadLongPhoto(File file, int orientation, int hScale) {
  SubsamplingScaleImageView imageView = new SubsamplingScaleImageView(this);
  imageView.setOnClickListener(onClickListener);
  imageView.setBackgroundColor(getResources().getColor(android.R.color.black));
  if (file != null && file.exists()) {
    if (orientation == 1) {//纵向图
      imageView.setMinimumScaleType(SubsamplingScaleImageView.SCALE_TYPE_CENTER_CROP);
      imageView.setImage(ImageSource.uri(file.getAbsolutePath()), new ImageViewState(0, new PointF(0, 0), SubsamplingScaleImageView.ORIENTATION_0));
    } else {
      imageView.setMaxScale(hScale);
      imageView.setImage(ImageSource.uri(file.getAbsolutePath()));
    }
  } else {
    imageView.setImage(ImageSource.resource(R.mipmap.failure_image));
  }
  return imageView;
}