[Interest] (no subject)

Bernhard B schluchti at gmail.com
Wed Aug 9 16:26:21 CEST 2017


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

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!
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