RFR: 8345041: IGV: Free Placement Mode in IGV Layout

[Emanuel Peter]

On Thu, 28 Nov 2024 13:45:45 GMT, Tobias Holenstein <tholenstein at openjdk.org> wrote:

> This PR depends on https://github.com/openjdk/jdk/pull/22430. To check out this PR locally: 
> 
> git fetch https://git.openjdk.org/jdk.git pull/22438/head:pull/22438
> git checkout pull/22438
> 
> 
> Introduce a Free Placement Mode to IGV, allowing users to position nodes freely without being limited to the hierarchical layout constraints.
> 
> In this mode, users can manually drag and place nodes anywhere within the space, giving them complete control over the visual arrangement of the graph. Connections between nodes will be rendered as straight (or S curved) lines, without recalculating or enforcing hierarchical constraints.
> 
> This feature is ideal for users who need a flexible, non-restrictive way to organize and visualize complex graph structures in a customized and intuitive manner. The free placement of nodes will remain persistent until the layout is reset or another layout mode is selected.

This is really amazing, the feature. Really would make me start using IGV.

I scanned the code changes quickly, and it seems reasonable, at least to a non-IGV developer 😅

src/utils/IdealGraphVisualizer/HierarchicalLayout/src/main/java/com/sun/hotspot/igv/hierarchicallayout/FreeInteractiveLayoutManager.java line 219:

> 217: 
> 218:                 double deltaX = posX - otherNode.getX();
> 219:                 double deltaY = posY - otherNode.getY();

What happens if this distance is zero? Does the division below behave ok?

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Marked as reviewed by epeter (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/22438#pullrequestreview-2468377365
PR Review Comment: https://git.openjdk.org/jdk/pull/22438#discussion_r1862333177