[Python] Tulip cannot select nodes if the nodes coordinators are not symmetric

[lqtruong]

Dear Tulip Dev,

Currently, we got an issue when we were trying to select the nodes of Tulip's view. Below are our investigation.

The below example is showing issue

#!/bin/python

"""Test interaction with view"""
from tulip import tlp
from tulipgui import tlpgui

WIDTH = 256
HEIGHT = 256

g = tlp.newGraph()

viewLayout = g.getLayoutProperty("viewLayout")
viewSelection = g.getBooleanProperty("viewSelection")
viewColor = g.getColorProperty("viewColor")
viewLabel = g.getStringProperty("viewLabel")

nodes = g.addNodes(4)
n1 = nodes[0]
n2 = nodes[1]
n3 = nodes[2]
n4 = nodes[3]
 
# (*) When the coordinators are not symmetric, the result was not as expected.
viewLayout[n1] = (-17,-5,0)
viewLayout[n2] = (-14,-4,0)
viewLayout[n3] = (-11,-5,0)
viewLayout[n4] = (-15,-7,0)


gui = tlpgui.createNodeLinkDiagramView(g)

gui.resize(WIDTH, HEIGHT)
gui.setQuickAccessBarVisible(False) 
gui.setOverviewVisible(False)
gui.centerView()
gui.draw()

for nodei in g.getNodes():
    worldToView = gui.worldToView(viewLayout[nodei])
    (found, node, edge) = gui.pickNodeEdge(worldToView[0], worldToView[1], True, False)
    print("Pick Node {}".format((found, node, edge)))
    
    # colorize selected node
    if found:
        viewColor[nodei] = (0, 0, 255)  # Blue
        viewSelection[nodei] = True
        gui.draw()  # reflect on UI
        
input("wait")

Expected: All nodes should be selected.
Actual result: None of the nodes were selected

But when I replaced the coordinators of the nodes with the symmetric ones, all nodes were perfectly selected as expected, below is the code that worked perfectly.

Replace

# (*) When the coordinators are not symmetric, the result was not as expected.
viewLayout[n1] = (-17,-5,0)
viewLayout[n2] = (-14,-4,0)
viewLayout[n3] = (-11,-5,0)
viewLayout[n4] = (-15,-7,0)

by

# Attention: to replace the previous nodes coordinators {e.g. previous code at (*)} 
#  by the symmetric ones as followings ==> The result is perfect.
viewLayout[n1] = (-3, 3, 0)
viewLayout[n2] = (-3, -3, 0)
viewLayout[n3] = (3, 3, 0)
viewLayout[n4] = (3, -3, 0)

Actual result: All of the nodes were selected (as expected)

Could you please help me to check this case? Thank you very much.

Best regards,
Truong.

[rgiot]

I do not know if it is a bug of your code, or Tulip or a lack of explanations in the documentation.
However, I have found the reason and a workaround.

Y axis needs to be reverted: instead of using the Y coordinate computed by worldToView, use the height of view substracted by this Y coordinate.
@p-mary or @anlambert : is it the normal behavior ? I let you close (or not) the comment depending on the answer. Because it has other impacts: the suer may change the height of the window; so it should be obtained programmaticlly and not hardcoded.

So your second test is faulty and does not work despite the apperances : the picked nodes are not the good ones, but the mirrored ones.

Look at this updated example that works:

#!/bin/python

"""Test interaction with view"""
from tulip import tlp
from tulipgui import tlpgui

WIDTH = 512
HEIGHT = 512

g = tlp.newGraph()

viewLayout = g.getLayoutProperty("viewLayout")
viewSelection = g.getBooleanProperty("viewSelection")
viewColor = g.getColorProperty("viewColor")
viewLabel = g.getStringProperty("viewLabel")

nodes = g.addNodes(6)
n1 = nodes[0]
n2 = nodes[1]
n3 = nodes[2]
n4 = nodes[3]

n5 = nodes[4]
n6 = nodes[5]
 
# (*) When the coordinators are not symmetric, the result was not as expected.
viewLayout[n1] = (-9, 9, 0)
viewLayout[n2] = (-9, -9, 0)
viewLayout[n3] = (9, 9, 0)
viewLayout[n4] = (9, -9, 0)

viewLayout[n5] = (3, 3, 0)
viewLayout[n6] = (3, -9, 0)

gui = tlpgui.createNodeLinkDiagramView(g)

gui.resize(WIDTH, HEIGHT)
gui.setQuickAccessBarVisible(False) 
gui.setOverviewVisible(False)
gui.setViewOrtho(True)
gui.centerView()
gui.draw()

for nodei in g.getNodes():
    worldToView = gui.worldToView(viewLayout[nodei])
    print("screen {}".format(worldToView))
    (found, node, edge) = gui.pickNodeEdge(int(worldToView[0]), HEIGHT-int(worldToView[1]), True, False)
    print("Pick Node {}".format((found, node, edge)))
    
    # colorize selected node
    if found:
        viewColor[nodei] = (0, 0, 255)  # Blue
        viewSelection[nodei] = True
        gui.draw()  # reflect on UI
        
input("wait")