CODEWITHSUNDEEP
androidlistviewimage-scaling
Nick
Nick

Reputation: 6385

Resizing Images in List

I have a bunch of images that are displayed in a list view (one per row). The image file I have is a pretty large resolution so I'll need to scale it down to be shown in the list view.

So, my questions is...is it faster to store two images (one regular and one thumbnail) so nothing has to be scaled on the fly OR is it faster to simply allow android to scale this larger image upon list creation?

Thanks! Nick

Upvotes: 0

Views: 298

Answers (2)

dmon
dmon

Reputation: 30168

The best approach depends on your particular use case. If you really want to resize the image to a thumbnail level (e.g. 150x150) and don't plan to have more than about a 30 images to display, the best approach would be to just keep a cache of the Bitmaps in memory without writing them to disk (at a cost of about 3 MB of memory for the 30 images). This way your ListView won't stutter while you scroll images in and out of the screen. You can of course keep the full version and display that when the user taps on the ListView item.

If you want to display a higher resolution version in the ListView, then you might have to get creative. Remember that you don't have much time to render each individual ListView cell to keep a smooth scrolling experience, and that decoding a large image file will take time, even if you're downsampling it and resizing it; the initial decoding time is the same, the only difference is the size in memory. In this case then it might be convenient to keep both the original and the smaller size version in disk to reduce the stuttering as you scroll.

Upvotes: 1

Amadan
Amadan

Reputation: 198324

Store two images to avoid your users having to wait to get the fullsize of every image even though all they're looking at are thumbnails, unless the images are bundled in with the app (i.e. not downloaded on the fly).

Upvotes: 1

Related Questions