Unity 4.6 - How to scale GUI elements to the right size for every resolution

Question

The new Unity 4.6 comes with a new GUI, when I change de resolution on Unity the UI Button scales perfectly but when I test on the Nexus 7 device the Button looks too small. Any

Answer 1

This becomes giant and convoluted once you start laying things out in code AND using a canvas scaler, so I wish to provide a thorough answer to save someone the hours I went through.

First, don't use anchoredPosition to position anything, unless you fully realize it is a 0.0 to 1.0 number. Use the RectTransform localPosition to do the actual laying out, and remember it's in relation to the parent anchor. (I had to lay out a grid from the center)

Second, put a canvas scaler on the parent layout object AND the inner ui pieces. One makes the layout in the right position, the other will resize your elements so they actually show up right. You can't rely on the the parent unless the children also have scalers (and Graphic Raycasters to touch them).

Third, if you have a scaler, DON'T use Screen.width and height, instead assume the screen is the same value you put for the scalers (hopefully you used the same, or know what you're doing). The screen width always returns the actual device pixels, retina devices too, but the canvas scalers DO NOT account for this. This probably gives unity the one remaining way to find actual screen dpi if your game wants it. Edit: This paragraph applies to any parent canvas connected to the code doing your laying out. Not stray canvases, you can probably mix it up. Just remember unity's guidelines on performance with canvases.

Fourth, the canvas is still a bit buggy. Even with the above working, some things don't render until you delete and recreate a canvas, if you re-open the scene or it crashes. Otherwise, the above is the general "rules" I've found.

To center a "grid of things" you can't just use half of the canvas scaler's width or height, you have to calculate the height of your grid and set the offset by half of it, otherwise it will always be slightly off. I just added this as an extra tip. This calculation works for all orientations.