Re: resolution independent px

Hi Johannes,

Reading the link, it looks like normally viewed displays with any
resolution between about 50 DPI and 140 DPI will have one CSS pixel
exactly equal to one device pixel; so resolutions outside that are the
definition of 'differs a lot' in the standard.

What's the overhead of asking the library to re-scale the image to the
size that it already is?  If it's significant, then maybe there needs
to be a special case for 1:1.

I start out with a bias against adding another run-time option, but
it's based on my not-very-relevant experience of adding an option to
dpid.

Contradicting myself, the standard implies that there could be an
option for viewing distance, in which case there could be a special
case to that option for 'never scale'.

Regards.
James.

On 1/18/15, Johannes Hofmann <[email protected]> wrote:
> On Fri, Jan 16, 2015 at 12:14:19PM -0300, Jorge Arellano Cid wrote:
>> On Fri, Jan 16, 2015 at 08:50:13AM +0100, Johannes Hofmann wrote:
>> > Hi,
>> >
>> > attached is a patch that would enable resolution independent
>> > handling of px as described in [1].
>> > It would result in roughly equally sized images on high and low
>> > resolution devices at the cost of a higher overhead for additional
>> > image scaling.
>>
>>   A long time ago, image scaling was relatively low overhead,
>> but since dillo got correct gamma correction, it became much
>> more expensive.
>>
>>   I remember testing this and the difference was noticeable.
>> It was left anyway because the amount of scaled images
>> in the average web page is low.
>>
>>
>> > Is there a need for something like this?
>>
>>   I don't know...
>>
>> > Should it be enabled via config option or should we do it
>> > automatically if we detect a DPI value that differs a lot from
>> > the standard value?
>>
>>   For me, it is hard to say without knowing the main use of it.
>> What I do know is that our scaling is CPU intensive, so I tend
>> to have it off unless necessary.
>
> It's only useful if you have a high resolution device where DPI is
> much higher than about 70. In that case images will be rendered
> very small.
>
> I currently don't have such a device, so personally I don't have
> any need for this now. I just wanted to get feedback from dillo-dev
> in case someone already ran into this issue.
>
> Cheers,
> Johannes
>
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