Bernhard: I don't use QML, but in my application I use a QAbstractItemModel-derived class and a QTreeView-derived class to display image thumbnails in the view. The way I make it speedy is to save the image as a thumbnail so the view items don't need to resize the image data at all.
Maybe you could save a thumbnail of an appropriate size when you're adding them to your model? --- Andy Maloney // https://asmaloney.com twitter ~ @asmaloney <https://twitter.com/asmaloney> On Fri, Aug 11, 2017 at 3:33 AM, Bernhard B <schluc...@gmail.com> wrote: > Hi Vlad, > > you mean the QQuickAsyncImageProvider? That one sounds really promising. > Will definitely try that out. Many thanks for the suggestion! > > Bernhard > > Am Donnerstag, 10. August 2017 schrieb Vlad Stelmahovsky : > >> threaded image provider might help >> >> On Thu, Aug 10, 2017 at 12:36 PM, Bernhard B <schluc...@gmail.com> wrote: >> >>> Hi, >>> >>> yesterday, I also tried to replace the Base64ImageProvider approach with >>> a subclassed QQuickPaintedItem which paints the image in it's paint method. >>> I imagined that this approach might be faster es no bade64 decoding needs >>> to be done. But unfortunately it looks like as it's performing even worse >>> that way. >>> >>> Bernhard >>> >>> Am Mittwoch, 9. August 2017 schrieb Bernhard B : >>> >>>> Hi, >>>> >>>> I would need some help from you guys on how to improve the ListView's >>>> performance. The problem is, that scrolling through my ListView sometimes >>>> feels a little bit sluggish. >>>> >>>> If I only display some text in the ListView's delegate I can scroll >>>> smoothly through my list. But as soon as there is a picture in the >>>> ListView's delegate I notice that I can't scroll smoothly through my list >>>> anymore. That's especially noticable if I try to scroll fast through my >>>> list. Every time I hit a picture while scrolling through the list I can see >>>> that there is a noticable delay until the picture is fully loaded. My >>>> assumption is, that those pictures are the reason why he scrolling feels so >>>> sluggish. >>>> >>>> My application currently works like this: >>>> >>>> * load 20 pictures via REST (pictures are base64 encoded) >>>> * populate list model >>>> * the Image component in the delegate uses a Base64ImageProvider (self >>>> written) to access the model's base64 encoded content and displays the >>>> image >>>> * if the user scrolls past a threshold another batch of base64 encoded >>>> pictures is fetched from the server >>>> >>>> I also found this document: http://doc.qt.io/qt- >>>> 5/qtquick-performance.html#rendering and tried to apply as much as >>>> possible. In detail I applied the following changes: >>>> >>>> * removed complex bindings from delegate >>>> * set sourceSize property for Image >>>> * increased cacheBuffer a bit >>>> * profiled with QML profiler and improved a few things >>>> >>>> But still, the ListView feels a bit sluggish. The strange thing is, >>>> that it's most noticable on Android whereas on Windows and iOs it is >>>> better. >>>> >>>> Does anyone have an idea on how to improve that? >>>> >>>> >>>> Any help is really appreciated. >>>> Thanks a lot! >>>> >>> >>> _______________________________________________ >>> Interest mailing list >>> Interest@qt-project.org >>> http://lists.qt-project.org/mailman/listinfo/interest >>> >>> >> >> >> -- >> Best regards, >> Vlad >> > > _______________________________________________ > Interest mailing list > Interest@qt-project.org > http://lists.qt-project.org/mailman/listinfo/interest > >
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