[haiku-development] Re: app_server 4k and more implementation
- From: Jessica Hamilton <jessica.l.hamilton@xxxxxxxxx>
- To: "haiku-development@xxxxxxxxxxxxx" <haiku-development@xxxxxxxxxxxxx>
- Date: Mon, 6 Oct 2014 12:28:08 +1300
On Monday, 6 October 2014, Alexander von Gluck IV <kallisti5@xxxxxxxxxxx>
wrote:
> On , Ralf Schülke wrote:
>
>> Hello List,
>>
>> i will start this thread to found a good way to implementet the K4,
>> ..K8 screen support aka "Retina Display".
>>
>> Basicly BeOS and Haiku works with pixel in a pixel matrix without add
>> value "px"
>> BRect (0, 0, 100, 300) and not BRect( 0px, 0px, 100px, 300px), so this
>> make it good for a implementation he work automaticly to scale from
>> pixel to dip.
>>
>> A simpel calculation are
>> PIXEL / DEVICE_PIXEL_RATIO = DIP
>> PIXEL = DIP * DEVICE_PIXEL_RATIO
>>
>> So we can implements two helper function as privat app_server code ig:
>>
>> float PixelToDpi(pixel)
>> {
>> // PIXEL / DEVICE_PIXEL_RATIO = DIP
>> return new_pixel_dip;
>> }
>>
>>
>> float DpiToPixel(dip)
>> {
>> // PIXEL = DIP * DEVICE_PIXEL_RATIO
>>
>> return new_dip_pixel;
>> }
>>
>> I found some information, i hope it help. the question is how smart
>> can we implementet this without braking the API and for automaticly
>> scaled.
>>
>> http://blog.qt.digia.com/blog/2013/04/25/retina-display-
>> support-for-mac-os-ios-and-x11/
>>
>> https://www.brandbuilderwebsites.com/blog/2012/03/29/device-independent-
>> pixel-formula-for-mobile-devices/
>>
>> https://bbs.archlinux.org/viewtopic.php?id=39665
>>
>> https://developer.appcelerator.com/question/
>> 125317/calculate-apps-density-pixel-width--height-using-
>> titaniumplatformdisplaycapsdpi
>>
>
> yeah, that was a concern when I was looking at reving the Accelerant API
> for multiple displays and hardware 3D.
>
> Monitor info should likely record the screen DPI from the driver to enable
> automatic detection of such things.
> https://github.com/haiku/haiku/blob/master/headers/os/
> add-ons/graphics/Accelerant.h#L161
>
> I think maybe going "dpcm" is a better idea (metric) (
> http://en.wikipedia.org/wiki/Dots_per_centimetre)
>
> As monitor_info is "experimental new Haiku API", I think it would be safe
> to add a uint32 dpcm item to the end?
Only if you remove the field for DPI. Having both is very poor design when
one is a constant factor of the other.
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