Fellow Blender, Pete Blois, has written a small application called Rooler that allows you to make measurements of everything visible on your screen. You can download it by clicking here.
Rooler helps solve a common problem you have when designing UIs. That common problem is figuring out how large something is or how much space exists between elements. To help with this, you have this nifty tool called Rooler which, to think about it differently, is like having a virtual ruler that you can use to measure things on your screen.
Rooler is a small application that soars above all of your windows and provides you with some common screen measurement tools:
For example, let’s say that I need to create a graphic whose width is the exact size as some text I have:
The above text is actually an image. Right clicking on the image and seeing its properties will give me the width of the image, but it may not translate to the actual width of the content stored inside it. Finding the size of the actual content is where a tool like Rooler comes in handy.
You can click on the Bounds icon to draw an overlay rectangle over the area you want to measure:
Once you have drawn the boundary, release the mouse cursor and Rooler will automatically create the smallest box that bounds all of your data:
Best of all, you all get the width and height of this bounding box as well, and you were able to do this without using another image editing tool and performing various (albeit simple) steps needed to get a similar value as what you see above.
I just showed you one example of what can be done, but you can do a bit more as well. Go check out Pete’s Rooler page for more examples and information on other things this tool does.