Many thanks Volker, Your reply is very helpful to me. I am currently using Qt5.15 (due to various reasons, I am not ready to use Qt6 yet), and I found that QML applications will depend on the Widgets library. Referring to Qt6, I separated Qt5 svgwidget and opengwidget, so that there is some optimization effect at present. Don't know if there are other similar optimizations in Qt6.
Regards, -- Lu YaNing Volker Hilsheimer <[email protected]> 于2022年6月16日周四 13:46写道： > QML/Qt Quick and Widgets are based on fundamentally different rendering > technologies. > > Widget applications have a backing store, which is (simplified) a raster > image for each toplevel window; that raster image has as many pixels as > required for the size of the window. When a line or text is drawn, pixels > are put into that backingstore image, which is then put on screen. Some > caching happens in Qt (for glyphs, small pixmaps, etc), but there is no > data structure maintained that represents the individual paint instructions. > > Qt Quick is based on a scene graph, which the GPU can very efficiently > operate on. That scene graph stores vectorized representations of rendering > primitives (quads and triangles), as well as textures, shader programmes, > etc. This data structures needs to live somewhere in memory. > > This is just one aspect. The QML engine’s data structures compared to the > purely binary compiled C++ is another aspect. > > > So, comparing the memory footprint of Quick and Widget applications is > comparing apples and pears. Keeping their memory footprint equivalent is, > generally speaking and by itself, not a meaningful goal. > > > Volker > > > > > > On 16 Jun 2022, at 14:32, YaNing Lu <[email protected]> wrote: > > > > > > > You didn't answer the question. > > > > > > > > > > The difference is that QML is a different technology from widgets. > > > > > > > > > > If you want more details, please use a memory profiler to size the heap > (as > > > > >opposed to memory mappings) and find out consumes most memory. > > > > Thanks Thiago, > > > > I understand that my program has a high memory footprint, which has a > > lot to do with my implementation, so I just wrote the demo for > comparison. > > QML and widgets use different technologies, can I understand the meaning > > of no comparison between qml and widgets programs. > > > > BTW, I re-uploaded my demo in > https://bugreports.qt.io/browse/QTBUG-104322. > > In fact, my problem is that there are two: > > > > Why does qml have higher memory usage than widgets.（At present, I am > also > > analyzing through source code and memory detection tools） > > > > If optimized based on qml demo, how to make its memory usage consistent > > with widget demo or similar. > > > > Regards, > > -- > > Lu YaNing > > > > Thiago Macieira <[email protected]> 于2022年6月15日周三 16:05写道： > > On Wednesday, 15 June 2022 02:51:27 PDT YaNing Lu wrote: > > > We read the USS of the demo for comparison, and the following is the > > > comparison data. > > > > > > 5.15.2 > > > qml-demo : 31.3M > > > widget-demo : 24.7M > > > > > > 6.2.4 > > > qml-demo : 36.0M > > > widget-demo : 22.4M > > > > What are you measuring here? What tool did you use? > > > > -- > > Thiago Macieira - thiago.macieira (AT) intel.com > > Cloud Software Architect - Intel DCAI Cloud Engineering > > > > > > > > _______________________________________________ > > Development mailing list > > [email protected] > > https://lists.qt-project.org/listinfo/development > >
_______________________________________________ Development mailing list [email protected] https://lists.qt-project.org/listinfo/development
