[Digikam-devel] [Bug 148238] New: fast switching between preview modes

[Dik Takken]

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http://bugs.kde.org/show_bug.cgi?id=148238         
           Summary: fast switching between preview modes
           Product: digikamimageplugins
           Version: unspecified
          Platform: unspecified
        OS/Version: Linux
            Status: NEW
          Severity: wishlist
          Priority: NOR
         Component: general
        AssignedTo: digikam-devel kde org
        ReportedBy: d.h.j.takken phys uu nl


Version:           0.9.2 (using KDE KDE 3.5.5)
OS:                Linux

It would be nice to allow fast switching between preview modes. I'm referring to the "original left, filtered right", 'original on top, filtered at bottom' and so on modes. Every time you switch, the preview needs to be re-rendered.

Maybe the preview could be rendered for the entire viewport (not just for the right half of the viewport for instance), stored in a memory buffer and re-painted when the preview mode changes.

Or even better: Maybe the preview could *always* be painted from a permanent memory buffer, which lives as long as the plugin dialog is active: When the dialog is opened, the buffer is created and a preview is rendered into it. The buffer is only updated when the user changes settings. Whenever the preview image needs to be re-painted, it can be quick-fetched from the memory buffer. When the dialog is closed, the buffer is destroyed.