Reproducing the issue
Go to the Welcome page in the Qt Creator and select the 'Camera Example'. Verify that your camera is working properly first by compiling it. Then add a QOpenGLWidget in the designer to the camera.ui form. Run again, now the webcam should stay black.
Specs:
Windows 8.1
Qt 5.5
This is how it looks like for me:
http://i.stack.imgur.com/oE2Pe.png
A little more backstory
I'm working on a project that requires a video feed to work with OpenGL. I was using a QAbstractVideoSurface to get the image data for individual frames. I ran into this issue by just trying to add a QOpenGLWidget into the mix to see what happens. I haven't looked further into it yet other than searching for other reports of this. I couldn't find anything specific though.
Related
I started studying QT on windows 7. But I had trouble on qt-creator 4.8.0. After I finished installing qt-creator-4.8.0, I found that certain fonts are blurry. You can see it the images below:
As you can see, some fonts are blurry. How can I fix it?
Note that on another computer it works fine.
when i try to use qt-creator-3.6.1,it shows black screen.the image show like this.
enter image description here
enter image description here
Perhaps this is an OpenGL driver issue. Probably your computer is a little bit older and the OpenGL drivers are outdated. You can try to find updates from your graphics card vendor but I'm having my doubts this will help. Changing to a Qt5 based Creator might also help.
I'm using ARM build of JavaFX from Gluon on my Raspberry Pi. It has Virtual Keyboard enabled, so every time I touch an input field -- the keyboard pops up. Is there a way to disable it? I've tried using -Dcom.sun.javafx.isEmbedded=false -Dcom.sun.javafx.touch=false -Dcom.sun.javafx.virtualKeyboard=none but that has no effect.
I need to do this to replace the default VK with a custom one, that supports different layouts and locales (and looks better, tbh). Right now both of them pop up, overlapping each other.
With JavaFX 11 -Dcom.sun.javafx.virtualKeyboard="none" works for Gluon builds. For JavaFX8 I haven't found a solution at the time except rebuilding from source.
This is QT5. Its on an embedded Yocto system, with QT drawing to the framebuffer, no X11. The problem is this. I want to play a video using gstreamer. So, I tried to launch gstreamer with gst-launch-1.0 linked to a touch event in QT. Problem is, it flickers as QT also tries to render frames.
Next, we tried Q media player. However, this proprietary gstreamer doesn't support playbin, so, I went into QGstreamerPlayerSession and modified the constructor to use gst_parse_launch to set up my pipeline instead of playbin.
This works, in that my video plays. However, there is still the same flickering! I tried to throw up a white rectangle before launching the video, but it still flickers.
How could I prevent QT from redrawing? Do I need an empty scene before playing the video? Or is there a function call to pause redrawing?
I could of course send a SIGSTOP to QT, play the video in an external application, then resume with a SIGCONT. That works, but is obviously a very inelegant and restrictive solution (I need the app to be processing in the background still as its controlling other things as well).
I have an example application that came with Qt (dialogs/standarddialogs) and modified it so that it displays dialog on every screen:
for(int i=0;i<app.desktop()->screenCount();i++)
{
Dialog* dialog = new Dialog(app.desktop()->screen(i));
dialog->show();
}
return app.exec();
When testing on Xnest on application default screen (the one from which the application has been started) everything works ok. However, on the other screen the icons in message boxes are not displayed correctly.
The problem can be reproduced on both solaris and linux. However, when I try Xephyr instead of Xnest the problem disappears (on linux). On the other hand this is not a problem with Xnest itself as on Exceed the problem can also be reproduced (but the icons are not displayed at all).
Has anybody seen this kind of problem? Do you think it might be a problem with Qt or configuration of X server? Or maybe I need to compile Qt with some special options?
It seems to be a bug in Qt X11 graphics system. If I set QT_GRAPHICSSYSTEM to raster the icons are displayed properly.
I haven't found anyone who's stated a problem similar to this, but then again maybe it's because I don't know the right term for the graphical glitch I'm having. This program worked and displayed just fine a week ago, but now it doesn't. I (or rather, "we," since it's a school project) haven't made any changes to it since then. It's made with QT, and running on CentOS. Here's a screenshot:
Screenshot of QT glitch
Whatever is behind the window shows in the background, and whatever happens in the window gets frozen on screen. For example, if a word is supposed to flash on the screen and then disappear and be replaced by another word, the first word does not disappear. Instead, the second word just appears on top of it.
Anyone able to point me in the right direction as to what could be doing this? I could post a code snippet, if I knew what part to post a snippet of. :S
Is the UI just one giant QGraphicsScene object? If so then it could well be an OpenGL driver issue. If not, then I'm going to guess that it's the underlying Qt painting system that has become corrupted, and just reinstalling Qt should do it.