how to keep good quality of label in terms of pixel while changing the font Size?

[SGaist]

Hi,

What font are you using ?
How are you using it ?
What version of Qt ?
What platform are you running on ?

[Yash001]

@SGaist Hi,

I am using font Segoe UI. I am working on Qt 5.6.0 & visual studio 2017 with window 64 bit system.

Here the code which I use for setting label of graph.

static QFont axisTitleFont("Segoe UI");
	if (axisTitleFont.pixelSize() == -1) {
		axisTitleFont.setPixelSize(14);
	}
	
	axisTitleFont.setBold(false);

// create the Plot object.

QwtPlot *plot = OBJ_NAME(new QwtPlot(), "qwt-plot");

// set the label of yLeft axis

                QwtText title;
		title.setFont(axisTitleFont);
		title.setText("Cuurent (mA)");
		plot->setAxisTitle(QwtPlot::yLeft, title);

// change the font size

plotHandler.plotTabConnections << QObject::connect(m_mainWindow, &MainWindow::AxisFontSizeChange, [=](int fontSize) {
		axisTitleFont.setPixelSize(fontSize);

		//use for setting the lable on axis
		QwtText title;
		title.setFont(axisTitleFont);

		//set the lable on Y axis
		title.setText("Current(mA)");
		handler.plot->setAxisTitle(QwtPlot::yLeft, title);
		
	});

[SGaist]

In that case, you should rather contact the authors of the Qwt library. They will be likely better suited to answer this question.

[Yash001]

@SGaist Thank You Sir. I will contact Qwt library authors.

[uwer]

@SGaist said in how to keep good quality of label in terms of pixel while changing the font Size?:

In that case, you should rather contact the authors of the Qwt library. They will be likely better suited to answer this question.

Ah no - this question goes to the font engine and how texts are rendered inside of Qt. The same issue will be there, when drawing with QPainter without Qwt.

[SGaist]

@uwer fair enough, better first rule out that this comes from there :) This allows us to concentrate on the problem at hand.

@Yash001 First thing, can you test that on a more recent version of Qt ? Qt 5.6.0 is pretty old and not supported anymore so it would good to first check whether it's something that was fixed in between. If you need a LTS release for your project then please use Qt 5.9.

[mrjj]

hi
I dont know about QWt but if we are talking QPainter
it really looks like its missing
painter.setRenderHints(QPainter::Antialiasing | QPainter::TextAntialiasing);
?

[Yash001]

@SGaist I can not update the QT version for window system. But I will update Qt version for MAC system and let you know.

[SGaist]

Testing on a more recent version doesn't mean that you have to remove your current version.

[Yash001]

@SGaist got it.