QT is very slow on windows CE if using raster painting-engine



  • I use QT 4.7.2 on windows CE 6.0 with raster graphicssystem, but QT is very slow.
    the device's CPU is enough fast.

    Why ?



  • It's very hard to answer your question if you don't further expand the description of the problem.

    Very slow compared to ... ?
    Are you performing some heavy processing in some of the slot functions called while executing the program ?
    Are you performing file I/O operations directly in the slot function ?
    Are you performing lots of graphical operations that cause multiple redraws instead of performing them off-screen and then doing a single redraw ?
    Etc. etc.

    Besides that, remember that even if the cpu is fast, if it has to handle all the graphical processing (i.e. minimal or no hardware support for graphical operations) it takes very little to look very slow compared to what you see on an x86 desktop computer.



  • One of the reasons may be the small page pool. I have the same experience. My Qtgui.dll is placed in a TF card.
    I build QT on wince 6.0 with full features enable. This results in a very big QTGui.dll, about 7 MB.
    WINCE 6.0 use page pool to run app, if your app is too big and the locality is not good enough, your app may run very slowly because the code segment will be page in and page out.


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