Zooming a selected region on QCanvasView

[wysota]

So I can't just give these text a inverted matrix.

Why not?

void Coordinate::draw ( QPainter & painter ){
QWMatrix m = painter.worldMatrix();
QWMatrix invm = m.invert();
//...
}

void Coordinate::draw ( QPainter & painter ){
QWMatrix m = painter.worldMatrix();
QWMatrix invm = m.invert();
//...
}

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So is there any possible way to solve the problem so that I can get a good performance after scaling these small-pointSize-texts ?

Try the one above.

About the second way to do the job, I couldn't fully understand how to work with this method. Dose that mean, I should add another widget into the canvasview to show these texts?

Not to the view but next to the view. Just like the scrollbars are. Unfortunately I don't see a simple way to set your own scrollbars (this would be the best), but you need to look for something simmilar.

But if I do it as this, it can't make sure that after the canvas being scaled these texts still have accordingly position to the coordinate.

Text won't be scaled. Only the "lines" of the ruler will. And knowing the scale of the view it should be easy to synchronise the scale and knowing position of scrollbars it should be easy to synchronise the translation.

[luffy27]

Why not?

void Coordinate::draw ( QPainter & painter ){
QWMatrix m = painter.worldMatrix();
QWMatrix invm = m.invert();
//...
}

void Coordinate::draw ( QPainter & painter ){
QWMatrix m = painter.worldMatrix();
QWMatrix invm = m.invert();
//...
}

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Could you explain to me that where should I add these code in my app?
In my zoomIn() slot or somewhere?

And I have another question about the code you give me. Besides these texts my own Coordinate also has some solid-lines, dash-lines as the attached picture show. Of course, I use the QPainter draw these lines as well as these texts. So I think that changing the painter's matrix will also affect these lines' size. As a result, texts will not be scaled, but lines will have the same thing.
That is not what I want.
Is that ture?

[wysota]

Could you explain to me that where should I add these code in my app?
In my zoomIn() slot or somewhere?

In the method where you draw your ruler (Coordinate?) items. drawShape() in your case probably...

So I think that changing the painter's matrix will also affect these lines' size.

Not if you set the matrix after drawing lines and before drawing text.

[nitriles]

maybe this helps a little, put it at the end:

def main(args):
    app = qt.QApplication(args)
    demo = make()
    app.setMainWidget(demo)
 
    #zoom
    zoomer = Qwt.QwtPlotZoomer(Qwt.QwtPlot.xBottom,
                               Qwt.QwtPlot.yLeft,
                               Qwt.QwtPicker.DragSelection,
                               Qwt.QwtPicker.AlwaysOff,
                               demo.canvas())
    zoomer.setRubberBandPen(qt.QPen(qt.Qt.green))
    #mouse coordinates
    picker = Qwt.QwtPlotPicker(Qwt.QwtPlot.xBottom,
                               Qwt.QwtPlot.yLeft,
                               Qwt.QwtPicker.NoSelection,
                               Qwt.QwtPlotPicker.CrossRubberBand,
                               Qwt.QwtPicker.AlwaysOn,
                               demo.canvas())
    picker.setTrackerPen(qt.QPen(qt.Qt.black))
 
    sys.exit(app.exec_loop())
 
# main()
 
 
# Admire
if __name__ == '__main__':
    main(sys.argv)
 
# Local Variables: ***
# mode: python ***
# End: ***

def main(args):
    app = qt.QApplication(args)
    demo = make()
    app.setMainWidget(demo)

    #zoom
    zoomer = Qwt.QwtPlotZoomer(Qwt.QwtPlot.xBottom,
                               Qwt.QwtPlot.yLeft,
                               Qwt.QwtPicker.DragSelection,
                               Qwt.QwtPicker.AlwaysOff,
                               demo.canvas())
    zoomer.setRubberBandPen(qt.QPen(qt.Qt.green))
    #mouse coordinates
    picker = Qwt.QwtPlotPicker(Qwt.QwtPlot.xBottom,
                               Qwt.QwtPlot.yLeft,
                               Qwt.QwtPicker.NoSelection,
                               Qwt.QwtPlotPicker.CrossRubberBand,
                               Qwt.QwtPicker.AlwaysOn,
                               demo.canvas())
    picker.setTrackerPen(qt.QPen(qt.Qt.black))
    
    sys.exit(app.exec_loop())

# main()


# Admire
if __name__ == '__main__':
    main(sys.argv)

# Local Variables: ***
# mode: python ***
# End: ***

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