String concatenation with QStringBuilder

Published Monday June 13th, 2011 | 14 Comments on String concatenation with QStringBuilder
Posted in C++, Performance, Qt

QString and QByteArray comes with very handy operator+ which allows you to write stuff like this: QString directory = /*…*/, name = /*…*/; QString dataFile = directory + QLatin1Char(‘/’) + name + QLatin1String(“.dat”); Very convenient. The QLatin1Char and QLatin1String are just there for correctness, you could omit those while writing your application. We have something […]

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QML Scene Graph in Master

Published Tuesday May 31st, 2011 | 80 Comments on QML Scene Graph in Master
Posted in OpenGL, Painting, Performance, Qt, Qt Quick

Earlier this week, we integrated the QML Scene Graph into qtdeclarative-staging.git#master. Grab the modularized Qt 5 repositories and start hacking! The primary way to make use of it is by running qmlscene or by instantiating a QSGView and feeding it your own .qml file. The import name has been upgraded to QtQuick 2.0, so upgrade […]

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Threaded HTTP inside QNetworkAccessManager

Published Friday April 29th, 2011 | 14 Comments on Threaded HTTP inside QNetworkAccessManager
Posted in Internet, Performance, Threads

Hi, My name is Markus and this is my first blog post on labs πŸ™‚ Since some time ago we integrated a change into QNetworkAccessManager that makes HTTP requests run in a separate thread. Someone asked for clarification on that, so here it goes πŸ™‚ The reason behind this was the way QtWebKit (based on […]

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QStrings and Unicode — optimising QString::fromUtf8

Published Friday March 25th, 2011 | 15 Comments on QStrings and Unicode — optimising QString::fromUtf8
Posted in C++, Performance, Qt

Other blogs in this series: Improving the string performance with more SIMD (or not) Related: String Theory Last time, I attacked the problem of the conversion from Latin 1 (ISO-8859-1) to UTF-16 in QStrings. Most character literals in C++ source code are actually in ASCII, which is a subset of Latin 1, which in […]

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Improving string performance with SIMD: the revenge (fromLatin1)

Published Wednesday March 23rd, 2011 | 17 Comments on Improving string performance with SIMD: the revenge (fromLatin1)
Posted in Assembly, Performance, Qt

I had a couple of boring days last week, so to motivate myself I decided to do one of my favourite pastimes: reading disassembly code (no, I don’t have a life). I usually do that to see how well the compiler has optimised certain sections of the code. By doing that, I can at the […]

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The convenient power of QML Scene Graph

Published Tuesday March 22nd, 2011 | 37 Comments on The convenient power of QML Scene Graph
Posted in OpenGL, Painting, Performance

QML on QGraphicsView is limited to only features that are fast enough and absolutely necessary to make nice UIs. Potentially slow features like composition modes, QPainterPaths, QGraphicsEffects and complex brushes are not supported. We have been trying to make it easy for you to create fast and responsive UIs, and hard to create sluggish ones. […]

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