Draw buffer

hjpark

Hi Guys,

I'm in trouble to draw a buffer on widget.. this is my code

    int imageWidth = IMAGE_WIDTH;
    int imageHeight = IMAGE_HEIGHT;
    int bytesPerPixel = 2; 
    int format = QImage::Format_RGB16; 
    QImage image( m_pCameraBuf[DATA_DEPTH], imageWidth, imageHeight, imageWidth * bytesPerPixel, format);
    painter.drawImage(30,100, image);

unsigned short *m_pCameraBuf[TOTAL]; is defined in the class and I allocated memory with malloc before this code.

and then I tried to compile it but facing the error below.

error: no matching function for call to 'QImage::QImage(short unsigned int*&, int&, int&, int, int&)'
QImage image( m_pCameraBuf[DATA_DEPTH], imageWidth, imageHeight, imageWidth * bytesPerPixel, format);
^
I'm a beginner . sorry but please help me to know what's wrong on my code..
thanks a lot.

jsulm

Your m_pCameraBuf is of type short[], right? It has to be a uchar array. See here http://doc.qt.io/qt-5/qimage.html#QImage-3

jsulm

And why m_pCameraBuf[DATA_DEPTH] and not just m_pCameraBuf?

hjpark

@jsulm
Thanks a lot for your help..

An external API " mtfReadFromDevice(m_hnDevice, (unsigned short**)m_pCameraBuf); " requires 2 buffers

unsigned short *m_pCameraBuf[TOTAL] => #define TOTAL 2

and, I can't change the code of mtfReadFromDevice becuase it has been provided with lib only

so, I tried to cast short to uchar like it
QImage image( (uchar *)m_pCameraBuf[DATA_DEPTH])

but, facing

error: invalid user-defined conversion from 'uchar* {aka unsigned char*}' to 'const QString&' [-fpermissive]
QImage image((uchar*)m_pCameraBuf[DATA_DEPTH]);

Please help me again.. thanks..

jsulm

@hjpark Please use the same QImage constructor a before:

QImage image(reinterpret_cast<uchar*>(m_pCameraBuf), imageWidth, imageHeight, imageWidth * bytesPerPixel, format);

And why do you pass m_pCameraBuf[DATA_DEPTH] and not m_pCameraBuf?

hjpark

@jsulm

hi..

I tried to compile with QT5.2.1 instaed of 5.7 and no more error with this code.. an it works well.

QImage image( (uchar*) m_pCameraBuf[DATA_DEPTH], imageWidth, imageHeight, imageWidth * bytesPerPixel, QImage::Format_RGB16, Q_NULLPTR, Q_NULLPTR);