Resolution indpendence

Barry Scott barry.scott at
Mon Jun 30 07:35:27 PDT 2008

Nicolas Mailhot wrote:
> Le vendredi 27 juin 2008 à 13:32 -0400, Behdad Esfahbod a écrit :
>> On Fri, 2008-06-27 at 18:06 +0100, Steven J Newbury wrote:
>>>> HAL sees that it's a TV, assumes a viewing distance of 4m, computes a
>>>> dpi-at-arms-distance value of 30 * 4/.7 = 171dpi.  Very decent.
>>> This may well be sufficient, but it is a hack.  Ideally it would be better
>>> to have a specific "typical viewing distance" value for the hardware device
>>> that the toolkits/font renderer/compositor could pick up and utilize in
>>> relevant contexts.  It's probably too late for the first two however.
>> There are two points of physical information:
>>   A) Dots per inch on the display surface (LCD panel, TV screen,
>> projector screen, The Wall, ...)
>>   B) Viewing distance
>> Those two are very real and can be measured.  If we have both, we can
>> compute a third value:
>>   C) Normalized dpi / angular resolution / whatever you call it.
>> Physical dpi times viewing distance does the job.
>> At the end, C is all the application developers care about.  That's why
>> I suggest we redefine application DPIs to be that.
> Actually they also need to care about
> D. Preferred user font size in pt (which is then converted in pixels
> using C)
> Without D people fake C to change what D should be like
E. Screen magnification factor.

I would like to be able to just add a magnification to make everything on
the screen either bigger or smaller. Images need to scale with text etc.
This is independent of D.


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