clicking pipe in viewer deletes it premptively

[IdrisMiles]

Description

When clicking on a pipe connection between 2 nodes, the original pipe is immediately deleted, and a live connection pipe is started. If you release the LMB having not connected to another port the connection between the original ports is disconnected.
It is this disconnection that should delete the pipe following the emitted connection_changed signal, however the pipe is already deleted from the sceneMousePressEvent.

This causes an issue if I disconnect the graph and viewers connection_changed signal (to make the graph not editable), the pipe should not be deleted on click, but rather after the connection_changed has fired

# my sample code
graph.viewer().connection_changed.disconnect(
    graph._on_connection_changed
)

Possible Solution

Remove the following line in the NodeViewer.sceneMousePressEvent function:

    if pipe_items:
            if not self.LMB_state:
                return
            pipe = pipe_items[0]
            attr = {IN_PORT: 'output_port', OUT_PORT: 'input_port'}
            from_port = pipe.port_from_pos(pos, True)
            from_port._hovered = True

            self._detached_port = getattr(pipe, attr[from_port.port_type])
            self.start_live_connection(from_port)
            self._live_pipe.draw_path(self._start_port, None, pos)
            # pipe.delete() <-- remove this line, let the signals handle this later

---

This is perhaps a niche bug to my use case so understand if this fix isn't suitable. However I think a general graph setting for enabling/disabling new connections would be great!

[jchanvfx]

Hey @IdrisMiles

Thanks for catching the bug 😸 I've been meaning to rewrite some of the code in the node viewer. I see your fix in the pull request it works, however if the user mouse releases on the same port it will cause a double up on the pipe items in the scene.

I've made some updates over the last few days and released v0.0.12, so clicking on a connection pipe now should not disconnect. You can also now spawn a new live pipe connection by holding down Shift and clicking on a pipe.

Cheers,
Johnny

[IdrisMiles]

ahh of course, my bad.

Thanks for the quick update!