How to remove black border around widget?
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Hello,
I am writing Qt application under Linux for displaing electronic maps. After drawing onto QLabel and resizing window I have a black border around QLabel (before resizing everything is fine).
I am drawing bitmap with Xlib function XPutImage to speed-up drawing@void MapView::paintEvent(QPaintEvent *)
{
GC context = XCreateGC(QX11Info::display(), winId(), 0, NULL);
XPutImage(QX11Info::display(), winId(), context, scr->ximage, 0, 0, 0, 0, scr->W, scr->H);
XFreeGC(QX11Info::display(), context);
}@@MapView::MapView(QWidget *parent) :
QLabel(parent)
{
setBackgroundRole(QPalette::Base);
setAttribute(Qt::WA_PaintOnScreen);
setAttribute(Qt::WA_NoSystemBackground);
setSizePolicy(QSizePolicy::Ignored, QSizePolicy::Ignored);
setFrameShape(QFrame::NoFrame);
setScaledContents(true);
setMouseTracking(true);
}@
and the main window widget
@ImageViewer::ImageViewer()
{
scrollArea = new QScrollArea;
mapView = new MapView(scrollArea);
scrollArea->setWidget(mapView);
setCentralWidget(scrollArea);
}@what is my mistake?
!http://imageshack.us/photo/my-images/442/pic3o.png/(screenshot)!
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Have you tried drawing bitmap with Qt?
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to Hostel:
these methods did not made any effect
I think that problem is bit deeper inside the Qtto Kxyu:
I am trying to draw bitmap with XPutImage.
All is right when i am drawing bitmap with
@QImage im(bitmap, width, height, Q_RGBA......);
label->setPixmap(QPixmap::fromImage(im));@
but it is too slow for me -
As I understand, the problem is with custom painting in painEvent() and property Qt::WA_NoSystemBackground - without this property there is no black border but after my painting by XPutImage() my qLabel widget immidiately repaints with background color
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Create a style with a 0 border width and call setStyleSheet.
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setStyleSheet("QLabel {border: 0px;}") + custom paintEvent causes an internal error
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Where are you setting the stylesheet? In the MapView constructor? Not sure why a custom paintEvent would get in the way. We do it all of the time but without the custom paintEvent.
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I have tryed both - inside constructor and outside.
Another variant is to draw bitmap with OpenGL and GLWidget
@glDrawPixels(scr->W, scr->H, GL_BGRA, GL_UNSIGNED_BYTE, (const GLvoid *)scr->bitmap);@
and the same effect - black border around my GLWidget. I am in frustration!) -
I think that Qt QScroll area works wrong - I have reimplemented it and had no problems with borders!