How to manually pan canvas

[novackb]

I've create a QwtPlotPanner and connected it to the Right mouse button. The panning functionality works perfectly.

I allow the user to select a data point in the canvas using a QwtPlotPicker. The data gets updated every N seconds. The selected point (referenced via an ID) therefore moves every N seconds. The point stays selected, but I'd like to manually pan the canvas so the selected point is always at the center.

I found a couple methods in QwtPlotPanner that looked promising: moveCanvas(), moved(), panned(), etc. But those aren't accessible.

Any suggestions?

[Uwe]

This has nothing to do with panning: simply use QwtPlot::setAxisScale().

Uwe

[novackb]

Is there a way to get what the current axis scale is on the QwtPlot? I've also got a zoomer and magnifier on this plot so the axis scale is always changing based on the user interaction. So when I get a data update I need to get the current axis scale and adjust them based on where the selected point is now located.

Thanks!

[Uwe]

• QwtPlot::axisScaleDiv( ... ) gives you get all information about the current scale.
• connect( axisWidget(...), SIGNAL( scaleDivChanged() ), ... ) tells you about any changes ( f.e. by zooming panning ) of a scale
• plot->canvas()->contentsRect() returns the geometry of the plot in paint coordinates.
• With QwtPlot::canvasMap() you have the transformation between both coordinate systems.

QwtPlotZoomer also has a method scaleRect() ( derived from its base class ). You can check the implementation of QwtPlotPicker::scaleRect() - Qwt is open source.

Uwe

[novackb]

Thanks for your help.

QwtPlot::axisScaleDiv(..) contains the information I was looking for.