Lock the scale to use magnifier to zoom in or out leads to crash

[qgib]

Author Name: dr - (dr -)
Original Redmine Issue: 15004
Affected QGIS version: master
Redmine category:unknown

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1. Open any vector layer
2. Check "Lock the scale to use magnifier to zoom in or out"
3. Scroll mouse wheel (zoom out)
4. QGIS crashes

Fatal: ASSERT failure in Job::startRender(): "pre-set DPI not equal to painter's DPI (10 vs 9.6)", file /tmp/buildd/qgis-2.15.0+git20160609+d1cac84+20trusty/src/core/qgsmaprenderercustompainterjob.cpp, line 77
Stacktrace (piped through c++filt):
/usr/bin/qgis.bin(+0x58b7)[0x5566fb9b38b7]
/usr/bin/qgis.bin(+0x5b9a)[0x5566fb9b3b9a]
/usr/lib/x86_64-linux-gnu/libQtCore.so.4(qt_message_output(QtMsgType, char const*)+0x21)[0x7fe2dc0c8bb1]
/usr/lib/x86_64-linux-gnu/libQtCore.so.4(+0x70ff9)[0x7fe2dc0c8ff9]
/usr/lib/x86_64-linux-gnu/libQtCore.so.4(qFatal(char const*, ...)+0x94)[0x7fe2dc0c9804]
/usr/lib/libqgis_core.so.2.15.0(QgsMapRendererCustomPainterJob::start()+0x3a0)[0x7fe2dc97c100]
/usr/lib/libqgis_core.so.2.15.0(QgsMapRendererSequentialJob::start()+0x1c0)[0x7fe2dc987950]
/usr/lib/libqgis_gui.so.2.15.0(QgsMapCanvas::refreshMap()+0x3ef)[0x7fe2dd6237f7]
/usr/lib/libqgis_gui.so.2.15.0(+0x585675)[0x7fe2dd6f0675]
/usr/lib/x86_64-linux-gnu/libQtCore.so.4(QMetaObject::activate(QObject*, QMetaObject const*, int, void**)+0x2da)[0x7fe2dc1e987a]
/usr/lib/x86_64-linux-gnu/libQtCore.so.4(+0x19a70a)[0x7fe2dc1f270a]
/usr/lib/x86_64-linux-gnu/libQtCore.so.4(QObject::event(QEvent*)+0x61)[0x7fe2dc1eda31]
/usr/lib/x86_64-linux-gnu/libQtGui.so.4(QApplicationPrivate::notify_helper(QObject*, QEvent*)+0x8c)[0x7fe2db56ee2c]
/usr/lib/x86_64-linux-gnu/libQtGui.so.4(QApplication::notify(QObject*, QEvent*)+0x270)[0x7fe2db5754a0]
/usr/lib/libqgis_core.so.2.15.0(QgsApplication::notify(QObject*, QEvent*)+0x8f)[0x7fe2dc83a0ab]
/usr/lib/x86_64-linux-gnu/libQtCore.so.4(QCoreApplication::notifyInternal(QObject*, QEvent*)+0x6d)[0x7fe2dc1d54dd]
/usr/lib/x86_64-linux-gnu/libQtCore.so.4(+0x1ad323)[0x7fe2dc205323]
/usr/lib/x86_64-linux-gnu/libQtCore.so.4(+0x1aa5f1)[0x7fe2dc2025f1]
/lib/x86_64-linux-gnu/libglib-2.0.so.0(g_main_context_dispatch+0x254)[0x7fe2d434ee04]
/lib/x86_64-linux-gnu/libglib-2.0.so.0(+0x49048)[0x7fe2d434f048]
/lib/x86_64-linux-gnu/libglib-2.0.so.0(g_main_context_iteration+0x2c)[0x7fe2d434f0ec]
/usr/lib/x86_64-linux-gnu/libQtCore.so.4(QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>)+0x71)[0x7fe2dc2027a1]
/usr/lib/x86_64-linux-gnu/libQtGui.so.4(+0x26bbe6)[0x7fe2db610be6]
/usr/lib/x86_64-linux-gnu/libQtCore.so.4(QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>)+0x2f)[0x7fe2dc1d40af]
/usr/lib/x86_64-linux-gnu/libQtCore.so.4(QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>)+0x175)[0x7fe2dc1d43a5]
/usr/lib/x86_64-linux-gnu/libQtCore.so.4(QCoreApplication::exec()+0x89)[0x7fe2dc1d9b79]
/usr/bin/qgis.bin(+0x9e23)[0x5566fb9b7e23]
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf5)[0x7fe2daae7f45]
/usr/bin/qgis.bin(+0x5239)[0x5566fb9b3239]
Aborted (core dumped)

[qgib]

Author Name: dr - (dr -)

---

• crashes_corrupts_data was changed from 0 to 1

[qgib]

Author Name: Nyall Dawson (@nyalldawson)

---

Can't reproduce - can you share some more details? Eg a sample project which demonstrates this?

---

• status_id was changed from Open to Feedback

[qgib]

Author Name: dr - (dr -)

---

It happens with any vector layer, demo: https://dl.dropboxusercontent.com/u/40653013/out.ogv

[qgib]

Author Name: Nyall Dawson (@nyalldawson)

---

Can you try with a clean .qgis2 config folder and see if you still have this issue?

[qgib]

Author Name: dr - (dr -)

---

Tried and got the same result. I noticed that if open new project, add vector layer and start zooming - when Scale in status bar becomes 0 canvas freezes and I can not zoom or pan map.

[qgib]

Author Name: Nyall Dawson (@nyalldawson)

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I'm not sure what's happening here. I can't reproduce locally, so there's got to be something specific with your setup which is triggering this. Have you got anything unusual happening with respect to DPI settings? Not running a hidpi display or anything? Changed anything with the video card drivers?

[qgib]

Author Name: dr - (dr -)

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There are no something specific with my setup. Faced with the same issue on laptop with Ubuntu 12.04:

Fatal: ASSERT failure in Job::startRender(): "pre-set DPI not equal to painter's DPI (10 vs 9.6)", file /tmp/buildd/qgis-2.15.0+git20160602+94077b2+16precise/src/core/qgsmaprenderercustompainterjob.cpp, line 77
QGIS died on signal -1Could not attach to process.  If your uid matches the uid of the target
process, check the setting of /proc/sys/kernel/yama/ptrace_scope, or try
again as the root user.  For more details, see /etc/sysctl.d/10-ptrace.conf
ptrace: Operation not permitted.
No thread selected
No stack.
gdb returned 0
Aborted (core dumped)

[qgib]

Author Name: Jürgen Fischer (@jef-n)

---

dr - wrote:

There are no something specific with my setup. Faced with the same issue on laptop with Ubuntu 12.04:

[...]

http://qgis.org/en/site/getinvolved/development/bugreporting.html#creating-a-backtrace has information about how to enable display of a stacktrace.

[qgib]

Author Name: dr - (dr -)

---

It looks like issue was fixed.

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• status_id was changed from Feedback to Closed
• resolution was changed from to worksforme

[qgib]

Author Name: Jürgen Fischer (@jef-n)

---

• category_id was configured as Unknown