Re: [isabelle] Isabelle2013-RC3 available for testing



On Sat, 9 Feb 2013, Arthur Peters wrote:

Isn't it possible to detect the DPI of the screen and set the font accordingly? I thought all the modern text rendering libraries did this, so you can set the font size in points and have it choose the correct pixel size based on the size and resolution of the display. It seems that this would solve the problem of the default being to big or small for some people. And it might only require changing one thing to tell the system you are using physical units instead of pixels.

The carnival is entering its hot and final phase ...

"Modern" things are just old things piled up over many decades. You can ask for display DPI information on various platforms and various rendering frameworks, but it often gives you just a constant value that happens to be the most popular physical resolution of the time when these interfaces were introduced. So it is 72 dpi for Mac OS (according to the first Mac) and 96 dpi for X11/Linux (according to classic Sun workstations).

You can see how I tried it for my tiny build_dialog window here:

https://bitbucket.org/isabelle_project/isabelle-release/commits/4cd2d090be8f https://bitbucket.org/isabelle_project/isabelle-release/commits/86389991636e

This was directly motivated by my brand-new Sony HD display. On Windows 8 I have specified a different DPI value explicitly, but MS lets certain old Windows applications paint into a bitmap that is then scaled up. I think that Apple plays other funny tricks with the even more dense Retina displays to fool applications.


For Isabelle2013 it should all work suffiently well for now.

It is better to have fonts a bit too large by default than too tiny.


	Makarius





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