Can't save QImage

[hvengel]

I am creating a QImage and I would like to save it to disk. But the QImage::save() always return false and no image is saved. The image is valid since I am displaying it in my Widget at the time I try to save it. My code looks like this:

QPainter painter(this);
 
QImage backGround;
 
 painter.setRedirected (this, &backGround, QPoint(0, 0)); 
 
painter.setWindow( 0, 0, pixcols - 1, pixrows - 1);
 
 // bunch of painter commands    
 
 painter.setRedirected (&backGround, this,  QPoint(0, 0));
 
 QString file = "image.png";
 if(backGround.save(file, "PGN", -1))
       qDebug("it worked");
 else
       qDebug("it didn't work");
 
 painter.setWindow( 0, 0, pixcols - 1, pixrows - 1);
 
 
 QRect rect(0, 0, pixcols - 1, pixrows - 1);
 
 painter.drawImage(rect, backGround, rect);

QPainter painter(this);

QImage backGround;
 
 painter.setRedirected (this, &backGround, QPoint(0, 0)); 

painter.setWindow( 0, 0, pixcols - 1, pixrows - 1);
        
 // bunch of painter commands    
 
 painter.setRedirected (&backGround, this,  QPoint(0, 0));
        
 QString file = "image.png";
 if(backGround.save(file, "PGN", -1))
       qDebug("it worked");
 else
       qDebug("it didn't work");
     
 painter.setWindow( 0, 0, pixcols - 1, pixrows - 1);
    
    
 QRect rect(0, 0, pixcols - 1, pixrows - 1);
     
 painter.drawImage(rect, backGround, rect);

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I have tried all kinds of variations with different image types (pgn, PNG, jpg, JPG, tif, TIF....) and nothing works. What am I doing wrong?

[aamer4yu]

did u try giving the name as "image" and not as "image.png" ??
am not sure if this is the problem ...

[ChristianEhrlicher]

Your create an empty (null) image - how should Qt save this image?

[hvengel]

I had not tried leaving off the file extension. But I just tested it and it did not change the behavior.

Yes it was NULL. So I fixed that by declaring the QImage like this:

QImage backGround(pixcols, pixrows, QImage::Format_RGB32);

[wysota]

What is the format "PGN"? Shouldn't it be "PNG"?

[David Burnett]

I am creating a QImage and I would like to save it to disk. But the QImage::save() always return false and no image is saved. The image is valid since I am displaying it in my Widget at the time I try to save it. My code looks like this:

Hi, did you ever solve this problem, I appear to be having the same issue

for (int i = 0; i < QImageWriter::supportedImageFormats().size(); ++i) {
		std::cout << QImageWriter::supportedImageFormats().at(i).constData()  << std::endl;
	}
		uchar *buffer = (uchar *)malloc(32 * 32 * 3);
 
	QImage image = QImage (buffer, 32, 32,  32 * 3, QImage::Format_RGB32);
	QString str = "/Users/vargol/Source/FractGo/test.bmp";
 
	bool saved = image.save(str);
 
	std::cout << "Saved image " << saved <<  std::endl;

for (int i = 0; i < QImageWriter::supportedImageFormats().size(); ++i) {
		std::cout << QImageWriter::supportedImageFormats().at(i).constData()  << std::endl;
	}
		uchar *buffer = (uchar *)malloc(32 * 32 * 3);
	
	QImage image = QImage (buffer, 32, 32,  32 * 3, QImage::Format_RGB32);
	QString str = "/Users/vargol/Source/FractGo/test.bmp";

	bool saved = image.save(str);

	std::cout << "Saved image " << saved <<  std::endl;

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bmp
ico
jpeg
jpg
png
ppm
tif
tiff
xbm
xpm
Saved image 0

bmp
ico
jpeg
jpg
png
ppm
tif
tiff
xbm
xpm
Saved image 0

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I've tried different suffixes, using a format string, everything I can think off..

[David Burnett]

Fixed it myself saw the RGB, didn't see the 32...d'oh.