TreeMap

[Fabien Hermenier]

Hi

I am starting using GWT. I want to make a treemap visualization of a structure, and it seems that only protovis-GWT provides the good widget. Google Charts provides the ideal visualization for my problem but it can not work offline and I am not sure that a GWT wrapper is available.

I'm just discovering the widget, and I have some questions right now.

- Does it support zoom ? In practice, I just want to change the root of the treemap. Most of the time incrementally by going to one of the direct children, but also directly clicking on a leaf. I don't care about fancy animation.

- I like to have variable border size, denoting the different levels of the treemap. Is this possible ? 

- I want to control the depth of the tree. As an example, if the tree as more than 3 levels, then the third level is just one rectangle that gather its children.

In practice, a lot of my requirements are aligned with the Javascript google-chart treemap: http://code.google.com/apis/chart/interactive/docs/gallery/treemap.html

If such features are not available, I will try to do this by myself. But I'm still a beginner in using GWT and I don't really practice Javascript and protovis so, this will takes times.

[Lars Grammel]

> I'm just discovering the widget, and I have some questions right now.
> - Does it support zoom ? In practice, I just want to change the root of the
> treemap. Most of the time incrementally by going to one of the direct
> children, but also directly clicking on a leaf. I don't care about fancy
> animation.

Regular zooming is supported in Protovis, however, your use case
sounds more like semantic zoom. I think you would need to implement
this, for example by listening for mouse clicks and then changing the
contents.

> - I like to have variable border size, denoting the different levels of the
> treemap. Is this possible ?

The protovis treemap padding might be the right thing, but this is not
implemented in Protovis-GWT yet. If you can confirm that you can do
this with Protovis, I'll add the functionality to Protovis-GWT.

> - I want to control the depth of the tree. As an example, if the tree as
> more than 3 levels, then the third level is just one rectangle that gather
> its children.

If you control the contents of the treemap by implementing your own
semantic zoom (see above), this is easily doable.

Hope that helps,

Lars

[Fabien Hermenier]

You are right for the purpose of the zoom. I wil try to implement it using a regular clicking event and a reconstruction.