Qt padding & margins in dockable windows

1
votes

In a Qt5.5 C++ program I have various QDockWidgets each containing one widget that [mostly] fills its QDockWidget. However, there's a 10px border around the widget which I can't get rid of.

Screenshot (extraneous space marked in red)

The following attempts didn't seem to achieve anything:

ui->dockable->layout()->setMargin(0);

ui->dockable->layout()->setSpacing(0);

ui->dockable->layout()->setContentsMargins(0,0,0,0);

ui->dockable->setContentsMargins(0,0,0,0);

ui->dockable->setStyleSheet("margin: 0px; padding: 0px");

ui->dockable->setStyleSheet("QDockWidget{ border: 0px }");

this->layout()->setContentsMargins(0,0,0,0);

To replicate the problem:

  • File -> new project -> Qt widgets application
  • Edit form mainwindow.ui
  • Drag dockwidget onto form
  • Drag other widget into dockwidget
  • Dockwidget background context menu -> Lay out -> vertically
  • Should give screenshot like above (in Windows 7)

Upgrading to Qt 5.7.0 doesn't help. Any ideas?

2
c++qtlayout
I haven't managed to get rid of it neither. But at least under macOS there seems to be no border... - Patrizio Bekerle
Could you post the exact code generating the posted screenshot. To see how you create your docking bars and widgets. I don't see some margins, even under Win7. - jpo38
Docking bars and widgets are created in Qt Creator's graphical Form Editor, which modifies mainwindow.ui. - OJW
Have you tried to set layout content margins to 0 from QtCreator? - jpo38

2 Answers

2
votes

After you updated your post...

You must do:

ui->dockable->widget()->layout()->setContentsMargins( 0,0,0,0 );

ui->dockable->layout() is not the layout you need to modify. QDockWidget contains a QWidget (a kind of main widget, always available when QDockWidget gets created), this is the one where your layout was created in from QtDesigner, and so you must use QDockWidget::widget() to access it.

Alternatively, as you create the GUI from QtDesigner, you can also use this tool to remove your margins, it will make the GUI look like that:

enter image description here

1
votes

Would be easier to help if you sent some pictures of what you have and want.

Wrote this piece of code as a sample (executed in a QMainWindow):

QWidget* centralWidget = new QWidget( this );
centralWidget->setStyleSheet( "background: blue");
setCentralWidget( centralWidget );

QDockWidget* dock1 = new QDockWidget( "docking bar1", this );
QWidget* widget1 = new QWidget( dock1 );
dock1->setWidget( widget1 );
widget1->setStyleSheet( "background: red");

QDockWidget* dock2 = new QDockWidget( "docking bar2", this );
QWidget* widget2 = new QWidget( dock2 );
dock2->setWidget( widget2 );
widget2->setStyleSheet( "background: green");

addDockWidget(Qt::LeftDockWidgetArea, dock1);
addDockWidget(Qt::RightDockWidgetArea, dock2);

blue central widget + 2 docking bars, one filled in red, the other in green (makes it easy to see the borders: they remain grey areas).

It shows like that here (Mint OS) (intentionally undocked the green docking bar):

enter image description here

See the green undocked docking bar grey borders. Now, apply it this stylesheet:

dock2->setStyleSheet( "QDockWidget { \
                             border: 0px \
                                   }" );

Then you get no border anymore:

enter image description here

But I'm not sure that will fix your problem. You should post screenshots because docking bar looking really depends on the OS. I see no margin when the docking bar is docked on my OS, but you probably see one (note that the grey vertical line between the red and blue area in my screenshots is not a margin but a slider that can be used to resize the docking bar, I don't believe you are trying to suppress this).