android - 使用网络服务和 picasso 加载图像，如何添加采样大小？

Question

我正在使用 Picasso 库在 ViewPager 中加载和显示图像。正在加载的图像具有高分辨率，我想为它们添加一个内采样大小。但是，我不知道应该如何或在何处添加此采样大小属性。我的 ViewPagerAdapter.java 类具有以下内容。

@Override
public Object instantiateItem(ViewGroup container, int position) {
   ImageView iv_page_image;
   inflater = (LayoutInflater) mContext
      .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
   View itemView = inflater.inflate(R.layout.viewpager_item, container,false);
   iv_page_image = (ImageView) itemView.findViewById(R.id.iv_page_image);
   String path = pageList.get(position).getPageImage();
   path = path.replaceAll(" ", "%20");
   if (path != null && !(path.equalsIgnoreCase(""))) {
      Picasso.with(mContext).load(path)
         .placeholder(R.drawable.placeholder_empty)
         .into(iv_page_image, new Callback() {
         @Override
         public void onSuccess() {

         }
         @Override
         public void onError() {
         }
      });
    }
((ViewPager) container).addView(itemView);
return itemView;
}

我想在图片中添加如下内容

private static int calculateInSampleSize(BitmapFactory.Options options,
        int reqWidth, int reqHeight) {

    final int height = options.outHeight;
    final int width = options.outWidth;
    int inSampleSize = 1;

    if (height > reqHeight || width > reqWidth) {

        // Calculate ratios of height and width to requested height and
        // width
        final int heightRatio = Math.round((float) height
                / (float) reqHeight);
        final int widthRatio = Math.round((float) width / (float) reqWidth);

        // Choose the smallest ratio as inSampleSize value, this will
        // guarantee
        // a final image with both dimensions larger than or equal to the
        // requested height and width.
        inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio;
    }
    return inSampleSize;
}

Answer 1

只需将 .fit() 添加到您对 Picasso 的调用，它就会自动计算出适当的 inSampleSize 以在解码图像时使用。

您可能还想使用 .centerInside() 或 .centerCrop() 来确保自动调整大小时图像的纵横比不会改变。