General and Desktop

@JacobNovitsky You can still use QPalette and/or a stylesheet for your dark design appearance of your app

Hi and welcome to devnet, Are you looking for something like described in this stack overflow answer ?

@Violet-Giraffe That was to retrieve the information and use it in the following calculations.

@BoLin just curious. How do you connect two nodes?

@SGaist said in Exclusive (write) access to a variable/data structure: @deisik composition is a core part of C++ and is encouraged over inheritance Then why care about C++ at all? You usually inherit when you want to augment the base class with new capabilities. In your case, you are leaking implementation details by doing so Leaking to whom or what, and why is it inherently a bad thing? If you need to lock the access to the whole data structure, then maybe you were putting the original lock in the wrong place Yes, when I need to dramatically change its contents. When I need to change/retrieve from another thread a single element in a list, I now use QReadWriteLock-enabled versions of regular getter/setter functions

@shuiliuduan It seems more a VTK problem than a Qt issue. You may post your issue to a VTK forum.

@Creaperdown you may have to wrap the right lib with or statically link it to your app in this case. rpath will lead your app to look for the linked libs first in a specified dir if your know exactly where the libs are located. LD_LIRARY_PATH will not work if your app is launched when os starts. But you can start your app as: env LD_LIRARY_PATH=... your app. ldd your app to make sure your app is linked to the right lib.

Use different ports - anything else will not work.

@RahibeMeryem Christian is right that proper formatting + a full compilable example would help . Anyhow, I think I spotted the issue already: if(QFile::copy("qrc:/qtlib/centerface.onnx" , tempFile)){ Use ":/qtlib/centerface.onnx" here, since QFile expects a file path, not a QUrl. (And yes, the difference between :/ and qrc:/ is very annoying, as you need to know the signature of the API to decide which one to use).

@CJha That is great. I might be forgetting, but I don't think ~ or # are actually regular expression special characters. However, the escape() method may replace every punctuation character with \-character (including non-ASCII characters like copyright) because that never does any harm/is allowed on any punctuation character. Or it might be enough to let * go to \* and then revert any \*s to plain *s (actually .* in your case).

@JonB I understood properly now. Thank you for your valuable answers. Have a nice day

@LiuXiaoHhan i figureout try this one in middlebtn pressing event setInteractive(false); and after releasing restore this status in QGraphicsView setInteractive(true);

@Timmy you may rely more on FFMpeg than on QMultiMedia. QMultiMedia is a very basic tool for now. I do not use it at all.

@Andrew23 That's like I said then! It has indeed found the function named UpdateWindow() in winuser.h, a Windows SDK header file. And it tells you that is hiding the class UpdateWindow you want it to pick up. You can wait for some C++ guru to suggest your best move. But one thing would work: completely delete your UpdateWindow class and pick some other name for it! Make sure you rebuild from scratch when you do so. Oh, for this error it tells you what you can do here: class UpdateWindow *updateWindow = nullptr; It even says you can click the message to make it do it for you.... I don't know if there will be other similar issues elsewhere, you will always have to use class UpdateWindow ..., might be simpler to rename your class.

I had this issue when I needed to draw axis and corresponding ticks. In Qt4, I can use the following code: for (int i = _Ymin; i <= _Ymax; i = i + _yGrid) { double yPos = (_Ymax-i)*_yscaleF*_yscalingF; double xPos = -_xmin*_xscaleF-_shiftX; if(yPos < (_Ymax-_Ymin)*_yscaleF-_shiftY+1) { glBegin(GL_LINES); glVertex2f(xPos-2, yPos); glVertex2f(xPos+2, yPos); glEnd(); renderText (xPos - offset,yPos+5 , 0, QString::number(i/10.0)); } } glScalef(_xscalingF,_yscalingF,0); However, when I try to migrate my code to Qt6, there's no renderText anymore. After searching on the web and investigating the source code of renderText, finally I found the solution, one needs to save/load gl status: glBegin(GL_LINES); glVertex2f(xPos-4, yPos); glVertex2f(xPos+4, yPos); glEnd(); qt_save_gl_state(); renderText(xPos - offset,yPos+5 , QString::number(i/10.0)); qt_restore_gl_state(); Here are the def of qt_save_gl_state, renderText, qt_restore_gl_state: static void qt_save_gl_state() { glPushClientAttrib(GL_CLIENT_ALL_ATTRIB_BITS); glPushAttrib(GL_ALL_ATTRIB_BITS); glMatrixMode(GL_TEXTURE); glPushMatrix(); glLoadIdentity(); glMatrixMode(GL_PROJECTION); glPushMatrix(); glMatrixMode(GL_MODELVIEW); glPushMatrix(); glShadeModel(GL_FLAT); glDisable(GL_CULL_FACE); glDisable(GL_LIGHTING); glDisable(GL_STENCIL_TEST); glDisable(GL_DEPTH_TEST); glEnable(GL_BLEND); glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA); } static void qt_restore_gl_state() { glMatrixMode(GL_TEXTURE); glPopMatrix(); glMatrixMode(GL_PROJECTION); glPopMatrix(); glMatrixMode(GL_MODELVIEW); glPopMatrix(); glPopAttrib(); glPopClientAttrib(); } void GLWidgetnew::renderText(double x, double y, const QString text) { GLdouble textPosX = x, textPosY = y; // Retrieve last OpenGL color to use as a font color GLdouble glColor[4]; glGetDoublev(GL_CURRENT_COLOR, glColor); QColor fontColor = QColor(glColor[0]*255, glColor[1]*255, glColor[2]*255, glColor[3]*255); // Render text QPainter painter(this); painter.translate(float(_shiftX),float(_shiftY)); //This is for my own mouse event (scaling) painter.setPen(fontColor); QFont f; f.setPixelSize(10); painter.setFont(f); painter.drawText(textPosX, textPosY, text); painter.end(); } Note that one might need to adjust the renderText function for some special purposes (e.g., scaling, translation etc) src code of the project can be found here QtSignalProcessing

I am able to run my app through code. Thank you so much All. Special thanks to @Christian-Ehrlicher. Great help!.

@Valso said in Qt (maybe 5) became sluggish recently. Any ideas why?: Now I installed these two and forced them to use the GTK file dialogs, so no more waiting for an eternity for the dialog to load. Then it sounds like a problem of KDE and not Qt. Yes, KDE is closely related to Qt, but it also extends Qt. Most likely it provides its own "native" file dialog for Qt. There is a difference between plain Qt programs and KDE programs. And you were (almost) right initially that KDE would imply Linux as OS, but Qt actually does not (as mentioned before). (Just for completeness sake: the official KDE programs are also available on Windows. I even have Kate installed.)

@Chris-Kawa Thanks so much Chris. You have saved me from making a systematic errror. Much appreciated.