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Resize NatTable on collapse and expand [message #1695515]

Fri, 15 May 2015 14:35

Shane Mills

Messages: 9
Registered: May 2014

Junior Member

Hi community,

we are currently working on a quite big rcp project and in my role as Software Architect I am evaluating NatTable as a potential solution for a variety of different use cases.

Although NatTable appears to be pretty complex when approaching it for the first time, there do not seem to be many alternatives to realize the high expectations of our usability designers.

I am trying to have NatTable dynamically adjust its height according to the visible contents of the underlying DataLayer. In this case we have a TreeLayer, so we are able to expand and collapse elements that have children.

Everything good so far, except from the fact, that I cannot find an appropriate mechanism to resize NatTable when elements get expanded or collapsed.

The requirement here is, that there should be no scrollbars and NatTable should not be bigger than needed to display all currently visible elements, since there will be multiple NatTable instances and certain other Widgets in the same Part.

Scrolling will be done by the Part itself.

So my question: Is there a way to tell NatTable to recalculate its height based on the current height of its content? And what would be the appropriate way to trigger this mechanism when the contents height changes?

By the way: Resizing of Row heights is deactivated and does not need to be considered for this case.

Thanks in advance for supporting my thinking and learning process Smile

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Re: Resize NatTable on collapse and expand [message #1695527 is a reply to message #1695515]

Fri, 15 May 2015 17:43

Dirk Fauth

Messages: 2803
Registered: July 2012

Senior Member

I'm not sure about your requirement, but it sounds like you need to listen to create an ILayerEventHandler for StructuralChangeEvents that performs layout operations on the NatTable control. But if I understand you correctly, you don't need the ViewportLayer in your composition.

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Re: Resize NatTable on collapse and expand [message #1695612 is a reply to message #1695527]

Mon, 18 May 2015 06:22

Shane Mills

Messages: 9
Registered: May 2014

Junior Member

Thank you for you reply Dirk,

I already figured out, that the ViewportLayer was obsolete due to the requirements.

Your suggested solution with the ILayerEventHandler for structural changes was exactly what I was looking for.

What I now do is just setting the Dimensions of the NatTable via natTable.setSize(...). It works perfectly, at least as far as I can see.
Is this the preferred way to dynamically change the layout of the NatTable, or could this mess up internal behavior in any way?

Thank you very much for your support so far Dirk.

Shane

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Re: Resize NatTable on collapse and expand [message #1695616 is a reply to message #1695612]

Mon, 18 May 2015 07:20

Dirk Fauth

Messages: 2803
Registered: July 2012

Senior Member

Quote:

Is this the preferred way to dynamically change the layout of the NatTable

It is the first time that I hear of somebody who is using NatTable that way. Usually the amount of data shown in a NatTable is bigger than the available space. Therefore dynamic layout calculations to shrink the NatTable if there are less items available than space are rare.

So it is hard to say if that is the "preferred" way. If it works for you it is ok. And I am not aware of another way right now.

Quote:

could this mess up internal behavior in any way?

I don't think it would mess up anything, because your are changing the dimensions of the Canvas that NatTable paints on.

[Updated on: Mon, 18 May 2015 07:21]

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Re: Resize NatTable on collapse and expand [message #1696371 is a reply to message #1695616]

Tue, 26 May 2015 07:32

Shane Mills

Messages: 9
Registered: May 2014

Junior Member

Sorry for the late reply and thanks a lot for yours Smile

I experienced, that only setting the size of the NatTable in the suggested way will not update its layout correctly and thus lead to unwanted layouting issues.

Instead of using the setSize method I tried to alter the heightHint of the NatTables layout data itself and it works fine for now, or at least I did not run into problems with this solution so far.

This allows me to have more than one NatTable on a single part with each NatTable only showing the currently visible rows and updating their height according to expand and collapse events.

For this I have registered an ILayerEventHandler for RowStructuralChangeEvents updating the layout data of the according NatTable.

Thank you very much for your support Dirk!

Shane

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