Invoking GUI plugins with -g causes QT error

[osrf-migration]

Original report (archived issue) by Jackie K (Bitbucket: jacquelinekay).

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On branch default, if I try to invoke a GUIPlugin with gazebo -g lib.so, Gazebo doesn't start and I get the error:

"QWidget: Must construct a QApplication before a QPaintDevice"

One can still load a GUI plugin by editing gui.ini, which is why this has been classified as minor, not major.

Plugins where this error occurs:
examples/plugins/gui_overlay_plugin_time
examples/plugins/gui_overlay_plugin_spawn
(in branch haptix_teleop_ux_test) plugins/GUIAratPlugin

[osrf-migration]

Original comment by Steve Peters (Bitbucket: Steven Peters, GitHub: scpeters).

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What if you open gzserver and gzclient in separate terminals? Then gzclient -g lib__.so

Does that work?

[osrf-migration]

Original comment by Jackie K (Bitbucket: jacquelinekay).

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Nope.

[osrf-migration]

Original comment by Jackie K (Bitbucket: jacquelinekay).

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• changed title from "Invoking GUI plugins with -g does not work" to "Invoking GUI plugins with -g causes QT error"

[osrf-migration]

Original comment by Jackie K (Bitbucket: jacquelinekay).

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• Edited issue description

[osrf-migration]

Original comment by Steve Peters (Bitbucket: Steven Peters, GitHub: scpeters).

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I can confirm the failure:

$ hg up default
$ cd examples/plugins/gui_overlay_plugin_time
$ mkdir build
$ cd build
$ cmake ..
$ make
$ gzserver &
$ GAZEBO_PLUGIN_PATH=$PWD && gdb gzclient
...
(gdb) r --verbose -g $PWD/libgui_example_time_widget.so
...
Gazebo multi-robot simulator, version 4.0.2
Copyright (C) 2012-2014 Open Source Robotics Foundation.
Released under the Apache 2 License.
http://gazebosim.org

QWidget: Must construct a QApplication before a QPaintDevice

Program received signal SIGABRT, Aborted.
0x00007ffff318fbb9 in __GI_raise (sig=sig@entry=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:56
56	../nptl/sysdeps/unix/sysv/linux/raise.c: No such file or directory.
(gdb) bt
#0  0x00007ffff318fbb9 in __GI_raise (sig=sig@entry=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:56
#1  0x00007ffff3192fc8 in __GI_abort () at abort.c:89
#2  0x00007ffff567ec92 in qt_message_output(QtMsgType, char const*) ()
   from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#3  0x00007ffff567eff9 in ?? () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#4  0x00007ffff567f804 in qFatal(char const*, ...) () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#5  0x00007ffff5cfed56 in QWidgetPrivate::QWidgetPrivate(int) ()
   from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#6  0x00007ffff5d0d95d in QWidget::QWidget(QWidget*, QFlags<Qt::WindowType>) ()
   from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#7  0x00007fffd73b8659 in gazebo::GUIPlugin::GUIPlugin() ()
   from examples/plugins/gui_overlay_plugin_time/build/libgui_example_time_widget.so
#8  0x00007fffd73b6a1a in gazebo::GUIExampleTimeWidget::GUIExampleTimeWidget() ()
   from examples/plugins/gui_overlay_plugin_time/build/libgui_example_time_widget.so
#9  0x00007fffd73b69d0 in RegisterPlugin ()
   from examples/plugins/gui_overlay_plugin_time/build/libgui_example_time_widget.so
#10 0x00007ffff67d5666 in gazebo::PluginT<gazebo::SystemPlugin>::Create (_filename=..., _name=...)
    at gazebo/common/Plugin.hh:168
#11 0x00007ffff67d46c3 in gazebo::addPlugin (_filename=...)
    at gazebo/gazebo.cc:99
#12 0x00000000004710d8 in parse_args (_argc=_argc@entry=4, _argv=_argv@entry=0x7fffffffd8e8)
    at gazebo/gui/GuiIface.cc:123
#13 0x0000000000471aa9 in gazebo::gui::run (_argc=4, _argv=0x7fffffffd8e8)
    at gazebo/gui/GuiIface.cc:252
#14 0x000000000044b6d9 in main (_argc=<optimized out>, _argv=<optimized out>)
    at gazebo/gui/main.cc:23
(gdb) 

[osrf-migration]

Original comment by Steve Peters (Bitbucket: Steven Peters, GitHub: scpeters).

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• set component to "gui"

[osrf-migration]

Original comment by Steve Peters (Bitbucket: Steven Peters, GitHub: scpeters).

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@iche033

[osrf-migration]

Original comment by Nate Koenig (Bitbucket: Nathan Koenig).

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• set version to "all"

[osrf-migration]

Original comment by Jennifer Buehler (Bitbucket: JenniferBuehler).

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I'm just looking at this too because that would be useful.

Though noticed that it wouldn't work anyway as gazebo_shared::addPlugin() only takes plugins of type SYSTEM_PLUGIN.
Aside from that, the gazebo_shared::setup() function is made for system plugins only and calls Load(argc,argv) and Init(argc,argv), which the
GUIPlugin doesn't have.

So I am guessing that the code to load the gui plugins from gazebo_client.cc is a remnant from previous versions.

The error happens because QApplication has to be created before the plugin, but the plugin is created from parse_args() in GuiIface.cc.

I created a pull request #2562 for this.

[osrf-migration]

Original comment by Louise Poubel (Bitbucket: chapulina, GitHub: chapulina).

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• changed state from "new" to "resolved"

Merged in JenniferBuehler/gazebo/gzclient_gui_plugin_loading (pull request #2562)

Load GUI Plugins with gzclient parameter -g, fixes issue 1311

→ <<cset 599f776>>