Saving already opened image ...

[Godlike]

I made a simple image viewer, now how do i save that image with save and also save as ? Can you paste me some code example how to do that.

I have read the image with:

QString fileName = QFileDialog::getOpenFileName(this,tr("Open File"), QDir::currentPath());
	if (!fileName.isEmpty()) 
	{
		QImage image(fileName);
		if (image.isNull())
		{
			QMessageBox::information(this, tr("ImageViewer"), tr("Cannot load %1.").arg(fileName));
                return;
		}
	imageLabel->setPixmap(QPixmap::fromImage(image));

QString fileName = QFileDialog::getOpenFileName(this,tr("Open File"), QDir::currentPath());
	if (!fileName.isEmpty()) 
	{
		QImage image(fileName);
		if (image.isNull())
		{
			QMessageBox::information(this, tr("ImageViewer"), tr("Cannot load %1.").arg(fileName));
                return;
		}
	imageLabel->setPixmap(QPixmap::fromImage(image));

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thx.

[jpn]

For saving as, check out: QFileDialog::getSaveFileName()
For saving QImage to a file: QImage::save()

[Godlike]

Well yes, this opens me the dialog to enter filename. But how do i actualy get my image to save to that filename ?

[Godlike]

To be more exact, done this:

void ImageViewer::save()
{
	QString s = QFileDialog::getSaveFileName(this,"Choose a filename to save under",QDir::currentPath(),"Images (*.png *.xpm *.jpg)");
	QImage image(s);
	QByteArray ba;
	QBuffer buffer(&ba);
	buffer.open(QIODevice::WriteOnly);
	image.save(&buffer, "JPG");
}

void ImageViewer::save()
{
	QString s = QFileDialog::getSaveFileName(this,"Choose a filename to save under",QDir::currentPath(),"Images (*.png *.xpm *.jpg)");
	QImage image(s);
	QByteArray ba;
	QBuffer buffer(&ba);
	buffer.open(QIODevice::WriteOnly);
	image.save(&buffer, "JPG");
}

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doesnt save nothing as i specify
What have i missunderstood ?

[jpn]

This is something I wrote a while back, maybe you'll find it usable

void ImageViewer::saveFileAs()
{
	// construct a filter of all supported formats
	QString filter;
	QList<QByteArray> formats = QImageWriter::supportedImageFormats();
	foreach (QString format, formats)
	{
		filter += QString("%1 files (*.%2);;").arg(format.toUpper()).arg(format);
	}
 
	// remove unnecessary chars from the end of the filter
	if (filter.endsWith(";;"))
	{
		filter.chop(2);
	}
 
	// get save file name
	QString selectedFilter;
	QString fileName = QFileDialog::getSaveFileName(this, 
		"Save image as", path, filter, &selectedFilter);
 
	if (!fileName.isEmpty())
	{
		// keep track of the current path
		path = QDir(fileName).path();
 
		// check for the selected format
		QString format = selectedFilter.split(" ").at(0);
		QFileInfo fi(fileName);
		if (!fi.suffix().endsWith(format, Qt::CaseInsensitive))
		{
			// remove possible incorrect suffix
			fileName.chop(fi.suffix().length());
 
			// set correct suffix
			fileName += "." + format.toLower();
		}
 
		// save image in the selected format
		if (!image.save(fileName, format.toAscii().constData()))
		{
			QMessageBox::information(this, "Image Viewer", QString("Unable to save %1.").arg(fileName));
		}
	}
}

void ImageViewer::saveFileAs()
{
	// construct a filter of all supported formats
	QString filter;
	QList<QByteArray> formats = QImageWriter::supportedImageFormats();
	foreach (QString format, formats)
	{
		filter += QString("%1 files (*.%2);;").arg(format.toUpper()).arg(format);
	}

	// remove unnecessary chars from the end of the filter
	if (filter.endsWith(";;"))
	{
		filter.chop(2);
	}

	// get save file name
	QString selectedFilter;
	QString fileName = QFileDialog::getSaveFileName(this, 
		"Save image as", path, filter, &selectedFilter);
	
	if (!fileName.isEmpty())
	{
		// keep track of the current path
		path = QDir(fileName).path();

		// check for the selected format
		QString format = selectedFilter.split(" ").at(0);
		QFileInfo fi(fileName);
		if (!fi.suffix().endsWith(format, Qt::CaseInsensitive))
		{
			// remove possible incorrect suffix
			fileName.chop(fi.suffix().length());

			// set correct suffix
			fileName += "." + format.toLower();
		}

		// save image in the selected format
		if (!image.save(fileName, format.toAscii().constData()))
		{
			QMessageBox::information(this, "Image Viewer", QString("Unable to save %1.").arg(fileName));
		}
	}
}

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[jpn]

doesnt save nothing as i specify
What have i missunderstood ?

Assuming that you want to save the shown image, put the "QImage image" as a member variable and use that same variable for loading and saving.

[Godlike]

Realy a newbie at this but i cant get it to work, thanx for sharing this code first. I made it this far, i always get unable to save image (path is ok to where it wants to save and extension). My code till now:

void ImageViewer::save()
{
 	// construct a filter of all supported formats
	QString filter;
	QImage image;
	QList<QByteArray> formats = QImageWriter::supportedImageFormats();
	foreach (QString format, formats)
	{
		filter += QString("%1 files (*.%2);;").arg(format.toUpper()).arg(format);
	}
 
	// remove unnecessary chars from the end of the filter
	if (filter.endsWith(";;"))
	{
		filter.chop(2);
	}
 
	// get save file name
	QString selectedFilter;
	QString s = QFileDialog::getSaveFileName(this, "Save image as", QDir::currentPath(), filter, &selectedFilter);
 
	if (!s.isEmpty())
    	{
 
	// check for the selected format
	QString format = selectedFilter.split(" ").at(0);
	QFileInfo fi(s);
 
	if (!fi.suffix().endsWith(format, Qt::CaseInsensitive))
	{
		// remove possible incorrect suffix
		s.chop(fi.suffix().length());
		 // set correct suffix
		s += "." + format.toLower();
	}
 
	// save image in the selected format
	if (!image.save(s, format.toAscii().constData()))
	{
		QMessageBox::information(this, "Image Viewer", QString("Unable to save %1.").arg(s));
	}
	}
}

void ImageViewer::save()
{
 	// construct a filter of all supported formats
	QString filter;
	QImage image;
	QList<QByteArray> formats = QImageWriter::supportedImageFormats();
	foreach (QString format, formats)
	{
		filter += QString("%1 files (*.%2);;").arg(format.toUpper()).arg(format);
	}

	// remove unnecessary chars from the end of the filter
	if (filter.endsWith(";;"))
	{
		filter.chop(2);
	}

	// get save file name
	QString selectedFilter;
	QString s = QFileDialog::getSaveFileName(this, "Save image as", QDir::currentPath(), filter, &selectedFilter);

	if (!s.isEmpty())
    	{

	// check for the selected format
	QString format = selectedFilter.split(" ").at(0);
	QFileInfo fi(s);

	if (!fi.suffix().endsWith(format, Qt::CaseInsensitive))
	{
		// remove possible incorrect suffix
		s.chop(fi.suffix().length());
		 // set correct suffix
		s += "." + format.toLower();
	}

	// save image in the selected format
	if (!image.save(s, format.toAscii().constData()))
	{
		QMessageBox::information(this, "Image Viewer", QString("Unable to save %1.").arg(s));
	}
	}
}

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[wysota]

I think you should actually use QFile if you want to write an image to a file instead of QBuffer.

The simplest way to save a QImage to a file should be something like this:

QImage img;
//...
QString filename = QFileDialog::getSaveFileName(this, "Choose file");
if(!filename.isNull()) img.save(filename, "PNG");

QImage img;
//...
QString filename = QFileDialog::getSaveFileName(this, "Choose file");
if(!filename.isNull()) img.save(filename, "PNG");

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A more complicated but more flexible way:

QImage img;
//...
QString filename = QFileDialog::getSaveFileName(this, "Choose file");
if(!filename.isNull()){
  QFile file(filename);
  if(file.open(QIODevice::WriteOnly)){
    image.save(&file, "PNG");
  }
}

QImage img;
//...
QString filename = QFileDialog::getSaveFileName(this, "Choose file");
if(!filename.isNull()){
  QFile file(filename);
  if(file.open(QIODevice::WriteOnly)){
    image.save(&file, "PNG");
  }
}

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Also remember to use "JPEG" not "JPG" for jpeg files.

[Godlike]

This makes file great, but its empty ? All black and not saved what i have opened. You can see code how i opened file in my first post.

thx.

[jpn]

As I said, make the QImage image member variable.
If you instantiate a new QImage as a local variable in the function where you save, it's not the same image than you are viewing!

Then change the line 4 in your first post from:

QImage image(fileName);

QImage image(fileName);

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to

image.load(fileName);

image.load(fileName);

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Load to and save the same image.

[Godlike]

imageviewer.cpp:29: error: ‘image’ was not declared in this scope
imageviewer.cpp:35: error: no matching function for call to ‘QPixmap::fromImage(<type error>)’
/usr/include/QtGui/qpixmap.h:105: note: candidates are: static QPixmap QPixmap::fromImage(const QImage&, Qt::ImageConversionFlags)
make: *** [imageviewer.o] Error 1

if i change line 4 to what u told me

[Godlike]

Oh and i would need to get that string fileName which is a name of that image then too to be visible in save function.

I just dont get it, simple as that

[jpn]

imageviewer.cpp:29: error: ‘image’ was not declared in this scope
imageviewer.cpp:35: error: no matching function for call to ‘QPixmap::fromImage(<type error>)’
/usr/include/QtGui/qpixmap.h:105: note: candidates are: static QPixmap QPixmap::fromImage(const QImage&, Qt::ImageConversionFlags)
make: *** [imageviewer.o] Error 1

if i change line 4 to what u told me

Did you declare a QImage member variable?

in imageviewer.h:

class ImageViewer ...
...
private:
   QImage image;
..

class ImageViewer ...
...
private:
   QImage image;
..

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Edit: and the same thing goes for the QString fileName.. You know how to declare member variables, and what they are for, right?

[Godlike]

Ups you got me big time. Dunno why exactly needs to be there

But i put it there (probably wrong again ), and i get this error ... again

imageviewer.h:38: error: field ‘image’ has incomplete type

i put it in imageviewer.h so it is private and like this:

class ImageViewer : public QMainWindow
{
...
private:
QImage image;
QString fileName;
};

Please dont hate me

[Godlike]

Forget it was a stupid include missing damn i forgot how to code it seems

And the silly thing works now ofcourse thanx for everything