Constructing QImage from QBytearray

Hi

I am reading a raw binary data from a file into QBytearray. I want to use the QBytearray to construct a QImage. My code is shown below.

Code:

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QFile fileIn (fileName);
fileIn.open(QFile::ReadOnly);
QByteArray data = fileIn.readAll(); 
QImage img(2048,1024,QImage::Format_Indexed8); 
img = QImage::fromData(data,QImage::Format_Indexed8);  
QPixmap qp=QPixmap::fromImage(img);
BPlaneIN->setPixmap(qp);

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Quote:

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error: conversion from `QByteArray' to `const uchar*' is ambiguous

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Could some tell me why I get this error message. I have used scanline to get this working but am confused as to why this method of loading the buffer doesnt

Regards

try something like this

Code:

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...
img = QImage::fromData(data,"PNG");//the second param is format name
...

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Thanks Spirit

But it isnt "PNG" format, it is raw 8bit data. The intention is to create an empty QImage, the load QByteArray with data from a file. Then use QImage::fromData to load the QImage buffer. I dont understand why I need to specify a file format?

It does stop the compiler warning. Why is that?

Regards

Quote:

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Originally Posted by dbrmik

I dont understand why I need to specify a file format?

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how do you think QImage recognize image format? from special field in data.
so, if you data have no specifiyed format then you need to fill QImage pixel by pixel. on this forum this is question was discussed many times use search by forum.

Hi

But I am specifying the image format it is "Format_Indexed8"

Code:

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//load pixel data
QByteArray data = fileIn.readAll();
 
//empty image
QImage img(2048,1024,QImage::Format_Indexed8);
 
//load pixel data into empty image from QByteArray
img = QImage::fromData(data,QImage::Format_Indexed8);

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I just dont understand why the above does not work?

Regards

read this reading and writting image files.
QImage::Format is not format of file, this is pixel format.

Hi

Thanks, Yes I've read it. The data loaded from the file is raw 8bit binary data. I want to load the data into QByteArray and then load the image buffer with the contents of QByteArray.

Is this QImage member funxction

Quote:

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bool QImage::loadFromData ( const QByteArray & data, const char * format = 0 )

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equivalent to

Code:

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void loadImageData(uchar *data, int rows,int cols,QImage *rawImage)
{
    uchar* row; 
    for (int i = 0; i < rows; i++)
    {
		//access each row of data values
		row= rawImage->scanLine(i);
		for (int j = 0; j < cols; j++) //width
            row[j] =data[i * cols + j] ;
    }
}

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Thanks for your advice