Reduce image stutter by using subsampling more often.

[greyson-signal]

Fixes #7208.

On some phones, zooming in on large images (say, a 4k image) would be slow and stutter a lot. This is due to ZoomingImageView using a regular PhotoView instead of a SubsamplingScaleImageView. ZoomingImageView decides whether or not to use a SubsamplingScaleImageView depending on whether the image has a dimension larger than BitmapUtil.getMaxTextureSize().

However, while that method will determine the maximum size of an image that is possible to render, it doesn't necessarily mean it can be rendered efficiently. There is some size at which some phones will have to continually re-upload a bitmap to the GPU, as seen in this systrace taken from a Moto E.

We could just use SubsamplingScaleImageView all the time (it has built-in logic to prevent tiling on smaller images), but given that it doesn't use Glide to load Bitmaps, we shouldn't be over-using it. As a result, I altered BitmapUtil.getMaxTextureSize() to have a cap of 2048, which from research and experimentation seems to be a good number (OpenGL operates in powers of 2 -- if 4096 is too big, 2048 is the next best bet).

Tested on the following devices. No scroll jank on images >= 2048x2048. No scroll jank on images < 2048x2048.

• Moto X (2nd Generation), Android 6.0
• Moto E (2nd Generation), Android 5.1
• Galaxy S3 Mini, Andoid 4.2.2

Example test image to induce jank:

[2-4601]

Tested f544b7d, can confirm it works on my device. Great fix.