Re: [Development] How to speed up QML for KDE5 without QML compiler

[Leslie Zhai]

在 2015年09月16日 17:51, Konstantin Tokarev 写道:

16.09.2015, 07:04, "Leslie Zhai" :

Hi great Qt and KDE developers,

I like QML, it is high speed development language, easy to create candy
UI and not difficult to debug. KDE4 began to use it in some projects,
for example, KScreen`s kcm module, it used QML to take place of
traditional QWidget. and KDE5, it is full of QML, for example, kwin`s
tabbox, plasma-desktop and plasma-workspace`s applet, sddm, etc.

For a new PC, there is no sharp difference between QML and QWidget, but
in a very very old PC, how old? about 7 years ago, QML is very slow! and
it needs to close all effects for KDE5, even that when clicked, for
example, calendar applet, it hang about 3+ seconds to showPopup.

There is commercial QML compiler, a very small example tried to use it
https://github.com/AOSC-Dev/AOSC-VersionHelper2
But is it suitable for huge projects just like KDE5 if bought a
commercial license? because not all KF5 components follow the Qt Quick
Compiler`s resource.qrc way, so is it able to compile? for example,
kickoff applet (the start menu of KDE5).

--
Regards,
Leslie Zhai - a KDE developer

You might want to use generic approach working for any scripting language:
1) profile; 2) find bottlenecks; 3) rewrite them in "fast" language (C++ here)

As for rewrite from QML to C++:

1. Try to move all business logic and computations to C++ classes, make this 
code
available to QML via QObject-derived classes (see "Defining QML Types from C++"
document and also docs for qmlRegisterType and qmlRegisterSingletonType)

2. Identify reusable QML items and rewrite them in C++ using class derived
from QQuickItem. See "Writing QML Extensions with C++" document.
Yes, plasma-framework 
https://projects.kde.org/projects/frameworks/plasma-framework/repository 
developed QML Extension Plugin and easy-to-import in QML example 
https://github.com/xiangzhai/plasma-helloworld


But such as plasma-workspace`s krunner 
https://projects.kde.org/projects/kde/workspace/plasma-workspace/repository/revisions/master/show/krunner 
and kwin`s tabbox 
https://projects.kde.org/projects/kde/workspace/kwin/repository/revisions/master/show/tabbox
I prefer to directly operate QML object in C++ via objectName too, so in 
this situation, it is not able to use QML Compiler, right? then is it 
better to re-architecture some KDE5 projects to follow the QML Extension 
Plugin way?


And is there some benchmark to compare before and after compiled with 
QML Compiler for small and big project?





Another possible cause of sluggish performance is suboptimal usage of OpenGL.
Try to use best drivers available for your graphics hardware. You might also
consider using OpenGL profiling tools.
Thanks for your advice ;-) I will fallback to light DE when OpenGL 
profiling score is low.







--
Leslie Zhai

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How to speed up QML for KDE5 without QML compiler

[Leslie Zhai]

Hi great Qt and KDE developers,

I like QML, it is high speed development language, easy to create candy 
UI and not difficult to debug. KDE4 began to use it in some projects, 
for example, KScreen`s kcm module, it used QML to take place of 
traditional QWidget. and KDE5, it is full of QML, for example, kwin`s 
tabbox, plasma-desktop and plasma-workspace`s applet, sddm, etc.


For a new PC,  there is no sharp difference between QML and QWidget, but 
in a very very old PC, how old? about 7 years ago, QML is very slow! and 
it needs to close all effects for KDE5, even that when clicked, for 
example, calendar applet, it hang about 3+ seconds to showPopup.


There is commercial QML compiler, a very small example tried to use it 
https://github.com/AOSC-Dev/AOSC-VersionHelper2
But is it suitable for huge projects just like KDE5 if bought a 
commercial license? because not all KF5 components follow the Qt Quick 
Compiler`s resource.qrc way, so is it able to compile? for example, 
kickoff applet (the start menu of KDE5).


--
Regards,
Leslie Zhai - a KDE developer

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