Windows 8.1 not repainting QGLWidget when using high contrast theme

nikita158

Repaints happen only if window is resized or moved outside desktop.
Tested on Qt 4.8.6/5.4.0 minGW/MSVC

main.cpp:
@#include <QApplication>
#include "glwidget.h"

int main(int argc, char *argv[])
{
QApplication a(argc, argv);
GLWidget w;
w.show();
return a.exec();
}@

glwidget.h:
@#ifndef GLWIDGET_H
#define GLWIDGET_H

#include <QGLWidget>
#include <QTime>

class GLWidget : public QGLWidget
{
Q_OBJECT
public:
GLWidget() : QGLWidget() {}
private:
GLclampf R() { return GLclampf(rand() % 255) / 255; }
protected:
void mousePressEvent(QMouseEvent *e) {
qDebug("\nMouse clicked. Going to repaint...");

    update();
    //updateGL();
}
void paintGL() {
    glClearColor(R(), R(), R(), 1.0);
    glClear(GL_COLOR_BUFFER_BIT);

    qDebug("repainted " + QTime::currentTime().toString().toAscii());
}

};

#endif // GLWIDGET_H@

saw same strangeness on Linux with AMD's proprietary drivers.

rebooted 10 times after changing appereance theme ;)

JKSH

Hi, and welcome to the Qt Dev Net!

QGLWidget has multiple known issues, and it has been deprecated in Qt 5.4.

Please use "QOpenGLWidget":http://doc.qt.io/qt-5/qopenglwidget.html instead.

nikita158

Thankx for answer&welcomes
Moving to QOpenGLWidget doesnt solve the problem.

hellogl2 example from Qt 5.4 also doesnt show anything till I set:
@QSurfaceFormat fmt;
...
fmt.setSwapBehavior(QSurfaceFormat::SingleBuffer);
QSurfaceFormat::setDefaultFormat(fmt);@

nikita158

Seems that problem is Qt-independent
Almost all OpenGL apps using double buffer doent show anything