<![CDATA[How to remove black border around widget?]]>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)!

]]>https://forum.qt.io/topic/10974/how-to-remove-black-border-around-widgetRSS for NodeWed, 04 Nov 2026 21:32:34 GMTWed, 02 Nov 2011 15:20:44 GMT60<![CDATA[Reply to How to remove black border around widget? on Wed, 09 Nov 2011 13:48:27 GMT]]>I think that Qt QScroll area works wrong - I have reimplemented it and had no problems with borders!

]]>https://forum.qt.io/post/116219https://forum.qt.io/post/116219Wed, 09 Nov 2011 13:48:27 GMT<![CDATA[Reply to How to remove black border around widget? on Tue, 08 Nov 2011 14:01:01 GMT]]>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!)

]]>https://forum.qt.io/post/116066https://forum.qt.io/post/116066Tue, 08 Nov 2011 14:01:01 GMT<![CDATA[Reply to How to remove black border around widget? on Tue, 08 Nov 2011 13:46:36 GMT]]>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.

]]>https://forum.qt.io/post/116065https://forum.qt.io/post/116065Tue, 08 Nov 2011 13:46:36 GMT<![CDATA[Reply to How to remove black border around widget? on Tue, 08 Nov 2011 13:34:10 GMT]]>setStyleSheet("QLabel {border: 0px;}") + custom paintEvent causes an internal error

]]>https://forum.qt.io/post/116062https://forum.qt.io/post/116062Tue, 08 Nov 2011 13:34:10 GMT<![CDATA[Reply to How to remove black border around widget? on Mon, 07 Nov 2011 15:48:58 GMT]]>Create a style with a 0 border width and call setStyleSheet.

]]>https://forum.qt.io/post/115944https://forum.qt.io/post/115944Mon, 07 Nov 2011 15:48:58 GMT<![CDATA[Reply to How to remove black border around widget? on Mon, 07 Nov 2011 13:24:28 GMT]]>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

]]>https://forum.qt.io/post/115909https://forum.qt.io/post/115909Mon, 07 Nov 2011 13:24:28 GMT<![CDATA[Reply to How to remove black border around widget? on Mon, 07 Nov 2011 12:13:38 GMT]]>to Hostel:
these methods did not made any effect
I think that problem is bit deeper inside the Qt

to 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

]]>https://forum.qt.io/post/115899https://forum.qt.io/post/115899Mon, 07 Nov 2011 12:13:38 GMT<![CDATA[Reply to How to remove black border around widget? on Fri, 04 Nov 2011 06:05:04 GMT]]>Have you tried drawing bitmap with Qt?

]]>https://forum.qt.io/post/115545https://forum.qt.io/post/115545Fri, 04 Nov 2011 06:05:04 GMT<![CDATA[Reply to How to remove black border around widget? on Thu, 03 Nov 2011 14:55:15 GMT]]>QLabel has a methods:
[code]
setFrameShape()
setFrameShadow()
setLineWidth() // set to 0?
setMidLineWidth()
[/code]
maybe this will help you.

]]>https://forum.qt.io/post/115490https://forum.qt.io/post/115490Thu, 03 Nov 2011 14:55:15 GMT