Embedding Qwt plot High Resolution

[giusepped]

I have the following problem.
If I print a plot, for example its pdf version, the resolution is high and acceptable.
Now, I would like to embed the plot in a TextDocument and print the document with the plots rendered as in the pdf file.
I tried to grab the widget containing the plot, inserting the image inside the document and thenprint out. But, as I expected, the quality of the plot is very low.
There is a way to solve this problem?
G

[Uwe]

Use QwtPlot::print - it renders to any kind of paint device. I recommend to use a QSvgGenerator (= vector graphics ) but you can also render to a QImage and save it in the format you like.

When you render to a QImage don't forget:

QImage image(...);
image.fill(Qt::transparent); // or whatever background you want to have
...

HTH,
Uwe

[giusepped]

Uwe,
I would like to use SVG but as I stated in another post, SVG does not handle very well the borders of my plots...

[giusepped]

Anyway, the way suggested by UWE produces a plot without axis.
I used the following code:

...
image = new QImage(400,600,QImage::Format_RGB32);
....
QImage*  MyPlot::getImage()
 
{	
 
         QSvgGenerator generator;
        QwtPlotPrintFilter filter;
   	int options = QwtPlotPrintFilter::PrintAll;
            options |= ~QwtPlotPrintFilter::PrintBackground;
            options |= QwtPlotPrintFilter::PrintFrameWithScales;
	    filter.setOptions(options);
 
	image->fill(Qt::white);
 
        return image;
    }

...
image = new QImage(400,600,QImage::Format_RGB32);
....
QImage*  MyPlot::getImage()

{	
    
         QSvgGenerator generator;
        QwtPlotPrintFilter filter;
   	int options = QwtPlotPrintFilter::PrintAll;
            options |= ~QwtPlotPrintFilter::PrintBackground;
            options |= QwtPlotPrintFilter::PrintFrameWithScales;
	    filter.setOptions(options);
	 
	image->fill(Qt::white);
 
        return image;
    }

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As you can see, the image is in poor quality too.

[Uwe]

a) Qwt 5.2 clips the curves at the canvas borders for SVG.
b) The posted code snippet is nonsense - but if it has something to do with the application you are using for rendering your image: 400x600 is a very low resolution.

If you want an high resolution image you need to create a much larger QImage ( the size of the image is the resolution !). But it's obvious that using Qwt 5.2 with SVG ( or PDF - what is also a vector graphics format ) is much better than using any raster graphics format that produces huge output.

Uwe

[giusepped]

I found a solution and it works good.

QPrinter printer(QPrinter::HighResolution);
...
QPainter p;
	int pw = printer.pageRect().width();
	int ph =printer.pageRect().height();
 
	p.begin(&printer); 
 
	p.save();
	m_document->adjustSize();
	QTransform tra;
	tra.scale(11,11);
	p.setTransform(tra);
 
 	m_document->drawContents(&p,printer.paperRect());
 
 
	p.restore();
	QRect rec(-10,0,pw-10,0.4*ph);
	p.translate(0,0.65*ph);
 	solarDiagram->print(&p,rec,filter);
	p.end();

QPrinter printer(QPrinter::HighResolution);
...
QPainter p;
	int pw = printer.pageRect().width();
	int ph =printer.pageRect().height();
	
	p.begin(&printer); 
	 
	p.save();
	m_document->adjustSize();
	QTransform tra;
	tra.scale(11,11);
	p.setTransform(tra);
 
 	m_document->drawContents(&p,printer.paperRect());
	
 
	p.restore();
	QRect rec(-10,0,pw-10,0.4*ph);
	p.translate(0,0.65*ph);
 	solarDiagram->print(&p,rec,filter);
	p.end();

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This is good for A4 paper. The plot is rendered as a vector graphic and I like it.
But I would scale the painter automatically. The value "11" is taken from a trial-and-correct approach.
Moreover, I noticed that if I translate the painter, Qwtplot does not print the title of the plot anymore. If I do not translate the painter everything is printerd.Why?

[Uwe]

Probably a bug in Qwt, that doesn't handle the translation. Try to translate the target rectangle instead of the painter.

Uwe

[giusepped]

How? May you a bit more detailed....
What do you mean for target rect?
G