android - 什么是带滑行的缩略图(0.5f)方法？

Question

什么是 .thumbnail(0.5f) 方法，这个方法中的 0.5f 是什么，为什么我们需要在下面的代码中使用它，请解释。

Glide.with(context).load(dataList.get(position).getArtworkUrl30())
                    .thumbnail(0.5f)
                    .crossFade()

                    .diskCacheStrategy(DiskCacheStrategy.ALL)
                    .into(holder.img);

Answer 1

thumbnail(0.5f) 设置缩略图相对于原始大小的大小。 0.5f == 缩小 2 倍，或原始尺寸的 50%。缩略图用于在加载全尺寸图像之前显示预览(而不是占位符或空白区域)。

来自文档:

This method is particularly useful in combinations of ListView and detail views. If you already display the image in the ListView, let's just say, in 250x250 pixels, the image will need a much bigger resolution in the detail view. However, from the user perspective, he already saw a small version of the image, why is there a placeholder for a few seconds until the same image gets displayed again (in a higher resolution)?

In this case, it makes a lot more sense to continue to display the 250x250 pixel version in the detail view and in the background load the full resolution. Glide makes this possible with the .thumbnail() method. In this case, the parameter is a float as the size multiplier: