gnuplot：为什么 gnuplot_qt 在某些 PC 上无法启动？

Question

I have a gnuplot script which works fine on Win7 and Win10 PCs.

set term wxt size 400,400
...

However, if I switch to qt terminal it works fine on some PCs, but on others I get error messages.

set term qt size 400,400
...

The error message suggests to reinstall the application? Which application? Which Qt platform plugin? I am working with gnuplot 5.2.6 and simply unpacked gnuplot from the file gp526-win64-mingw.7z from https://sourceforge.net/projects/gnuplot/files/gnuplot/5.2.6/

What exactly do I have to reinstall to get it working everywhere?

Addition: Some more findings.

On those PCs where the qt-terminals didn't work, I was running gnuplot 5.2.6, however, the qt-terminals worked with gnuplot 5.2.0 on the same PCs. Going back to gnuplot 5.2.0 is not a solution because it doesn't have some features which I need. Some differences of the "working" and "non-working" PCs were the Microsoft Visual C++ Redistributables. Some PCs have the 2008,2010,2012,2013 and 2015 versions installed. On the newest Win10 PCs there is even a 2017 version but no 2015 version. So, my current suspicion is that gnuplot 5.2.6 requires the 2015 version, whereas gnuplot 5.2.0 probably runs with the 2013 version. If it is like this, it would have been nice if gnuplot_qt.exe told me that this or that specific version is missing.

Currently, I don't have access to those PCs. So, further tests will take some more time.

Answer 1

I have never used gnuplot, however, I have recently debugged issues with Qt plugins. From the popup it is clear that the platform plugin has been found (windows), but could not be initialized.

It might just be that the plugin DLL is somehow corrupt, or that multiple versions of Qt are available on the machine, and for some reason version A tries to load plugins from version B (and fails).

The part of Qt that loads plugins has some debug output built in. I suggest you try to enable debug output and get more information about the error:

1. Get DebugView
2. Enable plugins debug output. This can be done by setting an environment variable: SET QT_DEBUG_PLUGINS=1
3. Start DebugView
4. Start gnuplot from the command line where you set the variable
5. Look for messages from gnuplot in DebugView. There might be some noise depending on what else is running in the system. DebugView collects output from all applications, but you can easily filter and search.

Debug messages should at least show exact paths to plugins that are being loaded. Most likely some additional information about the error will be shown too.

Answer 2

It's difficult to say without minimal code. But it looks like you didn't correctly deploy your application. 1) you should use windeployqt tool to create redistributable build. 2) you need to configure your app correctly with config: qt.conf . Ask if you need more help.

PS I got very difficult bug, when I got installed qt and redistributable qt on one PC. I found an answer here .

Answer 3

There is an answer in the question

In Gnuplot use the command

set term wxt

This is a quick fix that got around this problem. - nothing was plotting before with the plot command. There was an error message complaining about qt. Afterwards using this command in Gnuplot all the plot commands worked fine.

I post this answer here because it is a simple fix that sorted out the issue for me.

Answer 4

I run in a similar problems few months ago with another software that was using Qt on Windows.

I do not have a final solution for your problem but those are some of the steps I followed to fix the problem.

1. Ensure you have a clean windows

In order to ensure that your configuration will run in all Windows version, try to setup a clean installation with no third-party dependency installed.

Sometimes, you will find that you have installed several packages in the past that makes your system compatible with the software you are running. In order to avoid that, try to install a clean version if you are planning to release an installation or setup that must run in different PCs.

Extract the folder an try to run it. If it does not run, try to install Qt and add it to the system path.

2. Find missing dependencies

I used DependencyWalker to find the missing dlls, if any in my system.

Create a new folder and extract the files you just downloaded. Open with DepencyWalker the binaries you are going to run.

This software will tell you if you need to install any third-party library that is missing in your system (download them for MinGw from this page ).

Normally, you should add all those dlls into the 'bin/' folder.

Be aware that some of the dlls may be installed in one system and not in others because of the different Windows version they are using.

If DependencyWalker is not complaining anymore, zip the folder and try to run it in other systems.

3. Deploy for an installed Qt version

Qt provides a tool to copy all the dependencies from Qt that a binary need to run properly.

The Windows deployment tool windeployqt is designed to automate the process of creating a deployable folder containing the Qt-related dependencies (libraries, QML imports, plugins, and translations) required to run the application from that folder. It creates a sandbox for Windows Runtime or an installation tree for Windows desktop applications, which can be easily bundled into an installation package.

After installing Qt, try to run this tool in all the binaries to replace/updates the Qt dependencies in order to fix the problems with the Qt plugins.