[Qt-interest] Overlay in conflict to QPainter?

[unimd at web.de]

Hello everybody,

I am using overlays to render 2D stuff above my 3D-context. To do this I decided to use overlays and render them in the paintOverlayGL()-method. Furthermore I just want to swap the current buffer and not using swapBuffers(). Everything works fine, if I just draw a simple primitive like:

void vmOGLWidgetOverlay::paintOverlayGL()
{
 makeOverlayCurrent();

 HDC hdc = getDC(); //HDC hdc = GetDC(winId());
 
 int   nEntries = 4;            // number of entries in palette
 COLORREF crEntries[4] = {    // entries in custom palette
 0x00000000,     // black (ref #0 = transparent)
 0x000000ff,  // red
 0x0000ff00,     // green
 0x00ff0000,     // blue
 };
 // set up the layer palette
 wglSetLayerPaletteEntries(hdc, 1, 0, nEntries, crEntries);
 // realize the palette
 wglRealizeLayerPalette(hdc, 1, TRUE);

 glClear(GL_COLOR_BUFFER_BIT);
 if( MyCriticalObjectHit == true )
 {    
 glBegin(GL_TRIANGLES);
 glIndexi(1);
 glVertex2d(0, 0.5);
 glVertex2d(-0.5, -0.5);
 glVertex2d(0.5, -0.5);
 glEnd();
 }

 // just swap the overlay
 wglSwapLayerBuffers(hdc, WGL_SWAP_OVERLAY1);
 releaseDC(hdc); //ReleaseDC(winId(), hdc);
}

I use the paintEvent()-method to render my 3D-context which looks something like this:
void vmOGLWidgetOverlay::paintEvent(QPaintEvent *)
{
 makeCurrent();

 glMatrixMode(GL_MODELVIEW);
 glPushMatrix();

 initSettings();
 setupViewport(width(), height());

 glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 glLoadIdentity();
 glTranslatef(0.0, 0.0, -10.0);
 glRotatef(MyXRot/16.0, 1.0, 0.0, 0.0);
 glRotatef(MyYRot/16.0, 0.0, 1.0, 0.0);
 glRotatef(MyZRot/16.0, 0.0, 0.0, 1.0);
 MyLogo->draw();

 glShadeModel(GL_FLAT);
 glDisable(GL_CULL_FACE);
 glDisable(GL_DEPTH_TEST);
 glDisable(GL_LIGHTING);
 glMatrixMode(GL_MODELVIEW);
 glPopMatrix();

 // just swap the main plane
 HDC hdc = getDC();
 wglSwapLayerBuffers(hdc, WGL_SWAP_MAIN_PLANE);
 releaseDC(hdc);
}

Now, I would like to use a QPainter to draw some text... But somehow this doesn't work properly:

void vmOGLWidgetOverlay::paintOverlayGL()
{
 makeOverlayCurrent();
 QPainter painter(this);
 painter.setRenderHint(QPainter::Antialiasing);
 QFontMetrics fm(font());
 QString message(tr("My Message..."));
 int textWidth = fm.width(message);
 int textHeight = fm.height();
 painter.setPen(Qt::red);
 painter.drawText(topLeftPos.x(), topLeftPos.y(), textWidth, textHeight, Qt::AlignCenter | Qt::TextWordWrap, message);
 painter.end(); // no auto swap because of setAutoBufferSwap(false); in constructor

 if( wglSwapLayerBuffers(hdc, WGL_SWAP_OVERLAY1) == false )
 qDebug("no overlay swap");

 releaseDC(hdc); //ReleaseDC(winId(), hdc);
}

In my constructor I turn off the following:

 setAutoFillBackground(false);
 setAutoBufferSwap(false);

But I just can't see my 2D text in the overlay plane..
What am I doing wrong? Is there a problem using QPainter in an overlay plane? I don't understand why it doesn't work properly. Is anyone experienced on that area?
___________________________________________________________
Neu: GMX De-Mail - Einfach wie E-Mail, sicher wie ein Brief!  
Jetzt De-Mail-Adresse reservieren: http://portal.gmx.net/de/go/demail