I'm using qwt 6.1.3 for some Qt plotting work and just to test I created a new project, added the library, and pasted the simpleplot.cpp example code into Qtcreator.
A copy of the file can be view here: https://github.com/eiimage/qwt/blob/master/examples/simpleplot/simpleplot.cpp
The code has returned numerous errors.
curve->setSymbol(symbol);
The above code had to have a * put before symbol to prevent an error. Though I'm not sure if this is correct.
curve->setSamples(points);
Produces the error: 'class QwtPlotCurve' has no member named 'setSamples'. However, it's used in the example and also shows up in the document for that class. What might be causing this issue?
Thanks.
This problem was one of documentation. All online documentation and examples provided use the methods setSamples and setRawSamples to set the curve points. This is incorrect. The appropriate method is setData and setRawData.
Related
A little configuration information to start:
Xcode 13
Qt 5.15.5
iOS 14.7.1 (18G82) (I'm running on a device, not a
simulator)
Host MacOS Big Sur 11.6
I'm debugging a large Qt app, all written in C++, except for the necessary few files to make it work in iOS (so it's really an Objective-C++ app with an enormous amount of native C++ linked to it, everything of Qt it needs). I have a break point within the LoadApplication method - Qt has been built from source for development (that is, in debug configuration with symbols). There are a number of native Qt QUrl objects whose values I'd like to inspect. I have successfully installed lldbbridge.py, but I think the problem may be unrelated to that, because I saw it when I was using other tricks to see the data without the bridge. There is a method called toString on the QUrl class that produces a text representation of the URL (and another called toDisplayString that may be more human readable). These methods produce (of course) QString objects. So here are the failure modes:
First the bridge should be helping me to inspect the QUrl and all I see are the raw object descriptions that hide all the private interfaces. It isn't.
before I installed the lldbbridge.py script, I was able to view some of these objects (local variables, but not parameters), using code like expr url.toString().toStdString().c_str(). It still might work on local variables, but I would really like to be able to inspect parameters as well.
the error feedback I get is
error: <lldb wrapper prefix>:21198:9: module 'std' not found
#import std;
~~~~~~~^~~
this is a pretty legit error, because I have scoured my system and the internet for evidence of this std.framework whose existence is implied, and cannot find it, though its name suggests that it would be an assist to Objective-C or Swift to deal with std::string and the like. Possibly it was a thing in Xcode 12 that has been dropped in Xcode 13, but if so, it has no footprint on the web that I can find. Still, presumably Qt 5.15.5's lldbbridge.py was compiled and run and against it at some point in the recent past.
this isn't the only trick that doesn't work when inspecting a QString, with or without the bridge. I also tried expr (const wchar_t*)url.toString().toUtf16() and expr (const char*)url.toString().toUtf8() and so forth. The same error feedback results, complaining about the mysterious "std" framework or module.
and don't get too hung up on QUrl objects, because I get the same result with other QStrings.
one more symptom: if I do an expr #import std; in the lldb command line, it appears to work. That is, it gives no error feedback and appears to complete. This just makes the world weirder, because if exists, it must be hiding somewhere inside Xcode's contents, but I've done file searches in there, and see no evidence of such a thing. And if it does exist, why is the lldb wrapper prefix giving me grief? Could the wrapper be underspecified in terms of framework search paths, but the lldb command line not?
So as if it's not too obvious, here are my questions (besides WTF???):
Am I the first to see this? I've seen some forum talk about string inspection no longer working for others in Xcode 13 lldb, but the specific failure mode is different. Anyone else see this?
Does anyone have any idea about this mysterious "std" framework or module? Could its functionality have been sucked up into some other module or framework for Xcode 13?
Any ideas about work-arounds that I haven't thought of? I'm not a complete lldb novice, but I'm not an expert either.
I'd like to turn up the log levels look at those for clues, but I've never used that feature before, and I don't really even know where to FIND the logs.
I notice that the feedback suggests that there are at least 21198 lines in this "wrapper" BEFORE we get to the failing import statement. Seems a little excessive to wrap a request to view the contents of a string. Perhaps the whole wrapper is corrupted in some way. Any thoughts on how to test that hypothesis? How about a way to inspect the contents of the wrapper prefix itself?
Could the #import std; be a red herring and just co-lateral damage in some other unrelated failure mode? It's tempting to imagine it's some kind of std library support thing, but I don't want to assume too much at this point.
one more things about "std", whatever it is - lldb is super dynamic. It's always compiling inline code on-the-fly to support its functionality. That's the whole llvm magic. Is it possible it exists only as some inline text within lldb's source? And again, if so, why is it only selectively available?
Well, that's my nightmare. Unless my setup is horribly corrupted in some way and it's my unique curse, I'm sure this problem will show up for others, so cogent answers will make you a hero. Any pointers are appreciated. Thanks.
Following these instructions, I have already managed to fix the IntelliSense suggestions for my C++ hello world program using Qt headers. So for instance, when I type QString::, the class methods append, arg, etc. are suggested correctly. However, when I choose any of them, I would expect to read a short documentation comment describing what the selected method does do. Unfortunately, this information is not available.
I have also followed this tip and installed qt5-doc on my Ubuntu system, but I have no idea how I can use the .qch documentation files in VS Code. Do you have any pointer for me?
I am looking through the PhantomJS source code and I've encountered this line:
Q_PROPERTY(QString frameName READ frameName)
I don't understand how this is correct syntax, it's even missing a semi-colon.
Here is the fine in question on the Github repo, in case you need to sift through it https://github.com/ariya/phantomjs/blob/master/src/webpage.h
It's a macro that the Qt Library defines to have its own Property System. It uses its own macros mainly because of being platform independent (its aim is not to rely on specific compilers/os). I don't think I can add anything not in their reference docs.
im trying out raphael js examples from http://www.irunmywebsite.com/raphael/additionalhelp.php#pagetop.
i took the example of animateAlong and tried, but im getting an error of animateAlong function is not defined.
Also made sure that my code is inside window.onload. My Raphaël version 2.0.1
Thanks
It's been removed from Raphael2. See this link for a possible solution. (Haven't checked it out myself, so your mileage may vary...)
I have a Managed C++ WinForm that suddenly stopped showing in the VS 2005 designer. The error it shows is
Could not find type 'int'. Please
make sure that the assembly that
contains this type is referenced. If
this type is a part of your
development project, make sure that
the project has been successfully
built.
I don't even know where to start with this one. Does the designer only access the InitializeComponent(void) method when rendering the form? So my question is: where do you start troubleshooting designer errors?
EDIT: I forgot to mention that this code builds and runs perfectly. It only shows an error in the windows forms designer.
This is troubleshooting for C# but I'd assume a couple of the points mentioned here would help.
What's the state of play with "Visual Inheritance"
This is usually caused by a syntax error somewhere in the code that causes the designer to be unable to run the form to render it. The best method for this is ofent sadly just reading the code looking for the problem extra brace, missing string etc. The good news is that it is most likely easy to find since you know that it preceeds the INT in the error message.
Some possibilities:
* I cause this usually by accidentally hitting the keybaord and putting some extra characters at the top of a file
* Extra braces that make the class uncompilable - missing quotes, semicolons
* Something typed at the top that messes up a common include/using statement
Diagnostics
* Sometimes you can find this by dogin a build and seeing what lione is flagged with an error and then looking around it.
* More often then not I have to just open the source file and scan through it looking for the problem.