Efficiently update vector image in Qml Flickable on Android
I'm trying to view large vector image in Qml Flickable on Android. I created an instance of QQuickPaintedItem (named ViewItem) as a child of Flickable and reimplemented paint function in such way:
@void ViewItem::paint(QPainter *painter)
// width,height - sizes of Flickable item
QImage image(width, height);
// x,y - left-top coordinates of ViewItem on Flickable surface
It works so: when image is moved new pixmap of the whole ViewItem is created and rendered. And it's very slow. With an old Qt realization only a part of ViewItem was updated with the help of QScrollView::drawContents() function.
Maybe it's possible to make viewer work faster with the help of update() function but I failed to understand how it works. Can you advise principles to build efficient vector image viewer for Android with scaling and moving functions? Thanks!
Hi, you may try and use a QOpenGLFramebufferObject instead of the QImage as the render target, also if your image doesn't change much you can cache the painted image/texture in your class I guess?