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Amount of pixels scrolled with SWT mouseScrolled [message #657244]

Wed, 02 March 2011 06:53

Meghna Missing name

Messages: 9
Registered: March 2011

Junior Member

Hi,

I have added swt MouseWheelListener to FigureCanvas object, sequenceDiagramCanvas & overrided the mouseScrolled(MouseEvent e) method. The swt MouseEvent gives information about the no. of times the mouse is scrolled but not the number of pixels scrolled per scroll. In order to find out the no. of pixels scrolled(i.e. scrollOffset), I tried the following code:-

RangeModel model = sequenceDiagramCanvas.getViewport()
.getVerticalRangeModel();
int vBarOffset = Math.max(0, -model.getMinimum());
scrollOffset = sequenceDiagramCanvas.getVerticalBar()
.getSelection() - vBarOffset;

But the scrollOffset is returned zero for the first scroll, as sequenceDiagramCanvas.getVerticalBar().getSelection() is zero for the first scroll. From the subsequent scrolls, the scrollOffset value is correct.
Any pointers to get the no. of pixels scrolled for the first scroll or is there any other way?

[Updated on: Wed, 02 March 2011 07:45]

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Re: Amount of pixels scrolled with SWT mouseScrolled [message #657858 is a reply to message #657244]

Fri, 04 March 2011 11:28

Lakshmi P Shanmugam

Messages: 277
Registered: July 2009
Location: India

Senior Member

Hi,

Another way u can try is to attach Selection listener to the scrollbar and use scrollbar.getSelection() inside the Selection listener to get the value. This way you could get the pixels after the first scroll too.
Here is an example snippet that uses the SelectionListener of the ScrollBar --> http://dev.eclipse.org/viewcvs/index.cgi/%7Echeckout%7E/org. eclipse.swt.snippets/src/org/eclipse/swt/snippets/Snippet48. java

Lakshmi P Shanmugam

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