GL image rendering improvement

FYI, I've just added a feature to the openGL rendering context so that it'll cache textures used to render Images, and avoid re-uploading them to the GPU each time.

This means that there's probably no need to ever use the OpenGLImageType any more - for most purposes it'll make more sense to just use a normal Image, and let the GL context handle getting the data to the GPU when needed. This will also avoid any problems caused by android GL contexts getting deleted, as when that happens, the image will just get automatically re-uploaded again.

nice one Jules! thanks!

It's quite amusing to see the effect this has on the juce demo rendering test times.. On my machine, the image transform tests now run about 50-100x faster than the CoreGraphics/software rendering.

Just tried it in the Juce Demo and for Image ARGB Tiled i get:

SW 8 fps

CG 40fps

GL: 10000fps


This is on a MacBook 15" retina.