Multi-selection in viewer causes black boxes

[nikku]

Describe the Bug

As a user I'm embedding the viewer as recommended in the starter project. When I select elements no outline is shown, I can still react to selected events; this I expect.

However when I select more than one element a black box appears that hides the diagram:

Steps to Reproduce

1. open starter viewer example
2. select more than one element using SHIFT + click
3. see black box appear

Expected Behavior

• No black box appears
• (Alternative) Selection is not available for the viewer

Environment

• Browser: Chrome 110
• OS: Linux
• Library version: v14.0.0

[philippfromme]

I think that we need to be clear on what a viewer is. The default viewer in my opinion, should behave like viewing an SVG. No interactivity at all. I never liked the fact that you get selection behavior in the viewer. Now, there are use cases that need an interactive viewer. In these cases, users need to include the required features and stylesheets as well. Alternatively, we could offer something similar to the navigated viewer.

[philippfromme]

There would still remain the problem of interactive viewer and no selection outlines for connections. In the modeler selection is indicated by showing the bendpoints.

In an interactive viewer selecting connections should be indicated. We should have a solution for that.

[nikku]

No interactivity means that you cannot properly react to states in i.e. overlays. Hence the viewer would always offer basic interactivity, including hover and selection.

[philippfromme]

Overlays is a feature of an interactive viewer, I'd say.

[barmac]

I'd say there are 4 ways to display diagram:

• Modeler
• NavigatedViewer
• Viewer with some interactivity
• Displaying result of Viewer.saveSVG

Otherwise we should rename the Viewer to Renderer, as that's what it is without any interactivity.

[nikku]

Thanks for #2135 (comment) @barmac. I subscribe to it. Without interactivity the viewer is simply a renderer.

You can roll your own barebones renderer if you so desire on top of the BaseViewer package.