Hello,

Mostly I'm using debian sid with qt-4.6.3.
Now I try Qt 4.7.1 and my application can't load images from a database anymore (same code working with debians qt-4.6.3).
I configure Qt 4.7.1 with the following command:
Qt Code: 
  1. ./configure -confirm-license -prefix "/home/sebastian/qt-devel/qt4.7.1/" -opensource -fast -plugin-sql-mysql -plugin-sql-sqlite -system-sqlite -xmlpatterns -multimedia -audio-backend -phonon -svg -webkit -system-zlib -qt-gif -system-libtiff -system-libpng -system-libjpeg -optimized-qmake -lfontconfig -I/usr/include/freetype2 -qvfb -gtkstyle
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I have written a little example application (attached: sqlimagetest.tar.gz).
I get the following output:
Qt 4.6.3 => loading an image from file (show it as a pixmap), put it into the database, load it from the database (and show it as a pixmap, too)
Qt Code: 
  1. 5447 "ÿØÿà 
  2. sqlFileEngine::sqlFileEngine(const QString&) "questions/tImages/bild.jpg" 
  3. void sqlFileEngine::init() 
  4. "SELECT data FROM tImages WHERE LOWER(filename)=LOWER('bild.jpg')" 
  5. "ÿØÿà 
  6. sqlFileEngine::sqlFileEngine(const QString&) RAW: 5447 
  7. virtual qint64 sqlFileEngine::size() const 
  8. virtual QString sqlFileEngine::fileName(QAbstractFileEngine::FileName) const 3 
  9. sqlFileEngine::sqlFileEngine(const QString&) "questions/tImages/bild.jpg" 
  10. void sqlFileEngine::init() 
  11. "SELECT data FROM tImages WHERE LOWER(filename)=LOWER('bild.jpg')" 
  12. "ÿØÿà 
  13. sqlFileEngine::sqlFileEngine(const QString&) RAW: 5447 
  14. virtual bool sqlFileEngine::open(QFlags<QIODevice::OpenModeFlag>) OpenMode( "ReadOnly|Unbuffered" ) 
  15. virtual QString sqlFileEngine::fileName(QAbstractFileEngine::FileName) const 0 
  16. virtual bool sqlFileEngine::isSequential() const 
  17. virtual bool sqlFileEngine::seek(qint64) 0 
  18. virtual bool sqlFileEngine::isSequential() const 
  19. virtual qint64 sqlFileEngine::read(char*, qint64) 0 16384 
  20. virtual qint64 sqlFileEngine::read(char*, qint64) 5447 2745 
  21. virtual bool sqlFileEngine::isSequential() const 
  22. virtual bool sqlFileEngine::seek(qint64) 5447 
  23. virtual bool sqlFileEngine::close()
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Qt 4.7.1 => loading an image from file (show it as a pixmap), put it into the database; These both steps work properly. But loading the image from database fails.
Qt Code: 
  1. 5447 "ÿØÿà 
  2. sqlFileEngine::sqlFileEngine(const QString&) "questions/tImages/bild.jpg" 
  3. void sqlFileEngine::init() 
  4. "SELECT data FROM tImages WHERE LOWER(filename)=LOWER('bild.jpg')" 
  5. "ÿØÿà 
  6. sqlFileEngine::sqlFileEngine(const QString&) RAW: 5447 
  7. virtual qint64 sqlFileEngine::size() const 
  8. virtual QString sqlFileEngine::fileName(QAbstractFileEngine::FileName) const 3 
  9. virtual QString sqlFileEngine::fileName(QAbstractFileEngine::FileName) const 1
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Because showing jpeg file from harddisk works very well, I suppose QAbstractFileEngine behaves strange.

What did happen between Qt 4.6 and 4.7?
What did I wrong?