Spectrogram zooming change

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5th November 2010, 00:23
azcoder

Spectrogram zooming change

I was running Fedora 12 with qwt 5.2.0-1 and the spectrogram example allows you to left click on the display, then while holding the left mouse button down move the mouse to select a rubberband rectangle to be zoomed. This works quite well on Fedora 12. After installing Fedora 14 with qwt 5.2.1-1, the example no longer works like it did in Fedora 12. Now you must left click on the screen and release the mouse button to select rubberband mode. Then move the mouse to select the rubberband rectangle. Clicking on the left mouse again will then cause the zoom. How do I get back the old mode of operation? Is this intended? Where do I start looking for a solution? QWT? Qt? KDE? Fedora?

I have tried recompiling the example under Fedora 14 and it runs the same as the example compiled under Fedora 12, both wrong.

Thanks in advance for any help.

Jim
5th November 2010, 08:46
Uwe

Re: Spectrogram zooming change

The Qwt examples are intended to show what - and how things - can be done. In this version the spectrogram example shows a different mode of the zoomer/picker class. That's all.

Uwe
5th November 2010, 17:11
azcoder

Re: Spectrogram zooming change

Quote:

Originally Posted by Uwe

The Qwt examples are intended to show what - and how things - can be done. In this version the spectrogram example shows a different mode of the zoomer/picker class. That's all.

Uwe

I am not sure I made myself clear. So I will try again. I compiled the sample program under Fedora 12. Moved it to Fedora 14 and ran it. It runs different as I stated in my original message. I want it to run exactly like it did in Fedora 12. What do I need to do to have the example run the same on Fedora 12 and 14? Something must have changed (maybe a default) that now changes the mode of operation.

Jim
5th November 2010, 18:00
Uwe

Re: Spectrogram zooming change
Quote:

Originally Posted by azcoder

Something must have changed (maybe a default) that now changes the mode of operation.

Ah right - there was a bug in Qwt 5.2.0 ( and many earlier versions ) where the zoomer was initialized by ( QwtPicker::RectSelection & QwtPicker::ClickSelection ) instead of ( QwtPicker::RectSelection | QwtPicker::ClickSelection ). When fixing this bug I seem to have missed, that this breaks the compatibility of applications, that doesn't configure the zoomer.

If you want to have a selection model like in the bode example you have to add this line:
Code:

zoomer->setSelectionFlags(QwtPicker::RectSelection | QwtPicker::DragSelection);
In Qwt 6 "QwtPicker::RectSelection | QwtPicker::DragSelection" is the default setting of the zoomer.

Uwe