On Sat, Sep 29, 2012 at 7:21 AM, <[email protected]> wrote: > Hi,**** > > ** ** > > I am testing the image loading performance in Qt5, that the image with > different location (qt resource or file system) and using QImage or QPixmap. > **** > > ** ** > > Testing is based on a low end devices, and the result is shared as bellow: > **** > > ** ** > > Loading perf (240x320 png image)**** > > from resource**** > > from file system**** > > QImage**** > > 1.135s**** > > 1.132s**** > > QPixmap**** > > 1.146s**** > > 1.182s**** > > ** ** > > It seems the performance is really bad,,, does anyone have some insight > about which place can be the bottleneck ?**** > > ** >
My experience is with Qt4... but I do see that QFile was slow for me. I needed to parse a simple text file from a real disk (~10mb size, simple state machine, no regex, application run several times for disk IO to get working thus reducing the impact of HW). My first try was using QFile::readLine, and using QString. I then ported it to use ANSI C and char* (only for the parsing, the rest of the project was still using Qt4 classes). This simple refactoring (QFile -> fopen()) changed loading time (on windows): file1.txt: 515msec to 230msec file2.txt: 420msec to 155msec On linux (the same HW, double booting) the Qt QIO classes were not that slow, but the standard C functions were also faster. Is anyone seeing similar things?
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