Qt-interest Archive, March 2007
To use or not to use QGraphicsView
Message 1 in thread
Hello,
I am the main developer of Gwenview, an image viewer for KDE. I am currently
porting/rewriting it for KDE4, and I reach the point where I need a decent
ImageView widget. I am wondering whether it would be a good idea to use
QGraphicsView to show images.
I plan to had support for cropping and red-eye correction at a later time,
so I believe QGraphicsView items would make it really easy to implement a
way to select a part of an image. QGraphicsView would also be great to
implement nifty transition effects between images in fullscreen mode.
Still, I don't know if QGraphicsView would be the most efficient way to
display large images. The current ImageView widget of Gwenview contains
some tricky code to avoid blocking the application while scaling images. If
I want to really take advantage of QGraphicsView system, I need to let it
handle zooming so I need to be sure it won't block the application when
zooming.
What's your opinion on this? has anyone already used QGraphicsView to
display large QImage based items?
Regards,
AurÃlien
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Message 2 in thread
In regards to the rescaling (and not relevant to the rest of the
discussion).
Maybe it may be worthwhile looking at QtConcurrent for the rescaling
code. Would/should alleviate the tricky for you nicely, and gives you
full performance on multi-core systems to boot.
AurÃlien GÃteau wrote:
> Hello,
>
> I am the main developer of Gwenview, an image viewer for KDE. I am currently
> porting/rewriting it for KDE4, and I reach the point where I need a decent
> ImageView widget. I am wondering whether it would be a good idea to use
> QGraphicsView to show images.
>
> I plan to had support for cropping and red-eye correction at a later time,
> so I believe QGraphicsView items would make it really easy to implement a
> way to select a part of an image. QGraphicsView would also be great to
> implement nifty transition effects between images in fullscreen mode.
>
> Still, I don't know if QGraphicsView would be the most efficient way to
> display large images. The current ImageView widget of Gwenview contains
> some tricky code to avoid blocking the application while scaling images. If
> I want to really take advantage of QGraphicsView system, I need to let it
> handle zooming so I need to be sure it won't block the application when
> zooming.
>
> What's your opinion on this? has anyone already used QGraphicsView to
> display large QImage based items?
>
> Regards,
> AurÃlien
>
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>
>
>
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Message 3 in thread
Bill KING wrote:
> In regards to the rescaling (and not relevant to the rest of the
> discussion).
>
> Maybe it may be worthwhile looking at QtConcurrent for the rescaling
> code. Would/should alleviate the tricky for you nicely, and gives you
> full performance on multi-core systems to boot.
Yes, I do plan to check QtConcurrent, once I have figured out which widget I
should use to display my scaled images.
AurÃlien
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[ signature omitted ]
