(rqt launch) nodes do not show up (at first)

[dirk-thomas]

From @acornacorn on March 22, 2013 21:43

When I first start the RQT launch plugin, no nodes show up. I see the dotted tree lines on the left where the 2 nodes should be, but no information about the nodes. If I click on a different launch file and then click back to the original launch file then eventually I see the information about the nodes.

With some launch files, only some of the nodes show up. For example, run rqt, add the launch plugin, and set the package to pr2_moveit_config. The first launch file is demo.launch. I see slots (dotted lines) for 5 nodes, but only the first 2 (static transform publisher and joint state publisher) show up. Click on a different launch file (same problem). Then click on demo.launch again. Now all 5 nodes show up.

Copied from original issue: ros-visualization/rqt_common_plugins#53

[dirk-thomas]

From @130s on August 27, 2013 9:23

My incomplete diagnosis of the cause of this issue, for me or someone in the future making a patch.

In the line 202 or launch_widget.py:

            self._treeview.setIndexWidget(qindex_nodewidget, node_widget)

Here a widget for each ROS node is passed as an element to QTreeView. For some reasons QTreeView first creates lines without showing the widgets passed, and the second time the widgets are passed QTreeView shows them on it. As long as #lines-already-displayed < #nodes, widgets get displayed too when user chooses a new launch file. But if #lines-already-displayed > #nodes, the excess nodes are not displayed but only lines get generated.

I verified that roslaunch that is internally used returns proper values. So the cause is either in Qt or in my code esp. how I use QWidget as an element for QTreeView.