[Digikam-devel] [digikam] [Bug 337231] New: use high resolution pixmaps on retina displays [patch]

[Axel]

https://bugs.kde.org/show_bug.cgi?id=337231

            Bug ID: 337231
           Summary: use high resolution pixmaps on retina displays [patch]
    Classification: Unclassified
           Product: digikam
           Version: 4.2.0
          Platform: MacPorts Packages
                OS: OS X
            Status: UNCONFIRMED
          Severity: wishlist
          Priority: NOR
         Component: Preview
          Assignee: digikam-devel at kde.org
          Reporter: arnolda747 at gmail.com

On Mac OS X retina displays, photos in digikam look pretty pixelized, because
each logical pixel actually consists of 2x2 physical pixels, with
correspondingly sharp borders. This is due to the fact that Qt reports only
half of the actual resolution to the application, so that pixel-based layouts
do not get unreadable.  Qt then handles native resolution for UI elements,
rendering e.g. fonts at native resolution. Also, if pixmaps have a higher
resolution, Qt renders them at native resolution. However, at present, the
pixmaps that digikam provides to Qt are constructed at logical resolution.

I have patched digikam to provide higher resolution pixmaps and would like to
contribute this patch. It makes use of the fact full resolution images are
loaded if "Embedded preview loads full-sized images" is set. The displayed
pixmaps in preview and slide show are then made large enough to contain the
full resolution preview image (or a part of it), rather then just the (logical)
screen pixels covered. By this, Qt scales the pixmap to match the physical
screen resolution, giving a pretty brilliant picture on a Macbook Retina. The
fix also changes the Info.plist to make Mac OS X aware that digikam can handle
the high resolution.

Reproducible: Always

Steps to Reproduce:
1. Start digikam with a retina display (e.g. Macbook Retina)
2. Preview any 5+ MPixels photo
Actual Results:  
The preview or slideshow are displayed pixelized, with logical pixels
consisting of 2x2 physical pixels each.

Expected Results:  
The preview should be displayed in native resolution, i.e. without blocking
pixels.

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