Link Tasks To each other

[poautran]

In GitLab by @LudoBroche on Jun 21, 2025, 09:18 GMT+2:

IO of tasks needs to be link to each other.

The tasks should be position correctly for best clarity and links display should minimize crossing

Assignees: @LudoBroche

Migrated from GitLab: https://gitlab.esrf.fr/workflow/ewoks/ewoksdraw/-/work_items/2

[poautran]

In GitLab by @LudoBroche on Jun 21, 2025, 09:21 GMT+2:

created branch 2-link-tasks-to-each-other to address this issue

[loichuder]

Discussion with @LudoBroche

• We can use https://github.com/depetrol/pyelk to layout the graph. ELK is a powerful library for graph layouting that also take "ports" (node input handles) into account. When given the graph as input, pyelk can give use the coordinates of the nodes but also of the node "ports" (i.e inputs)
• Once we have the node ports coordinates, we can create the links.

[LudoBroche]

@loichuder

Quick test converting our graph to elk and to compute the task position.

def graph_to_svg(graph: TaskGraph,layout_option: dict, graph_path):

    svg_tasks_by_id = {}

    elk_graph = {"id":"root","layoutOptions":layout_option,"children":[],"edges":[]}

    for node_id, node_attrs in graph.graph.nodes.items():
        node_inputs = _get_all_node_inputs(node_id, node_attrs)
        node_outputs = _get_all_task_output_names(
            node_attrs["task_type"], node_attrs["task_identifier"]
        )
        svg_task = SvgTask(
            task_name=node_id,
            input_names=[n.name for n in node_inputs],
            output_names=node_outputs,
        )
        svg_tasks_by_id[node_id] = svg_task
        task_desc = {"id": node_id, "width": svg_task.width, "height": svg_task.height}
        elk_graph["children"].append(task_desc)



    for source, target, link_attrs in graph.graph.edges(data=True):
        edge_desc = {
            "id": f"edge_{source}_{target}", 
            "sources": [source], 
            "targets": [target],
        }
        elk_graph["edges"].append(edge_desc)

    
    elk = ELK()
    result = elk.layout(elk_graph)

    # Compute Canvas size should be done dirrectly in Canvas object. 
    children = result["children"]
    max_x = max(child["x"] for child in children)
    max_y = max(child["y"] for child in children)
    max_width = max(child["width"] for child in children)
    max_height = max(child["height"] for child in children)
    canvas_width = max_x + max_width + CANVAS_MARGIN
    canvas_height = max_y + max_height + CANVAS_MARGIN

    canvas = SvgCanvas(width=canvas_width, height=canvas_height)
    svg_background = SvgBackground(canvas_width, canvas_height)
    canvas.add_element(svg_background)

    for child in children:
        svg_task = svg_tasks_by_id[child["id"]]
        svg_task.set_translation(x=child["x"], y=child["y"])

        canvas.add_element(svg_task)
    
    canvas.draw(graph_path)

[LudoBroche]

pyelk doesn't provide the links rounting algorithms form native elk :(

[loichuder]

The algorithms or the parameters (https://eclipse.dev/elk/reference/algorithms/org-eclipse-elk-layered.html) ?

[LudoBroche]

I ask AI to translate a lightweight orthogonal router from elk. It's not the fancy phase-5 routing algo.
I added the calculated links to svg (manually), just to have a result quickly.