[FIXED] Margins in PyQtGraph's GraphicsLayout

Issue

Having a simple graphics layout with PyQtGraph:

from pyqtgraph.Qt import QtGui, QtCore                                              
import pyqtgraph as pg                                                              

app = QtGui.QApplication([])                                                        
view = pg.GraphicsView()                                                            
l = pg.GraphicsLayout(border='g')                                                   
view.setCentralItem(l)                                                              
view.show()                                                                         
view.resize(800,600)                                                                

l.addPlot(0, 0)                                                                     
l.addPlot(1, 0)                                                                     

l.layout.setSpacing(0.)                                                             
l.setContentsMargins(0., 0., 0., 0.)                                                

if __name__ == '__main__':                                                          
    import sys                                                                      
    if (sys.flags.interactive != 1) or not hasattr(QtCore, 'PYQT_VERSION'):         
        QtGui.QApplication.instance().exec_() 

Whichs outputs:

How could I get rid of the small margins which are between the green external line and the window borders?

I could do the trick and use l.setContentsMargins(-10., -10., -10., -10.), and that works:

But it seems to me like a dirty trick and there should be another parameter which is setting that margin. Could this be possible? Is there another margin parameter which I could set to 0 to get the same results?

Solution

I think this might be a Qt bug. There's an easy workaround:

l = pg.GraphicsLayout()
l.layout.setContentsMargins(0, 0, 0, 0)

To understand this, let's look at a modified example:

from pyqtgraph.Qt import QtGui, QtCore
import pyqtgraph as pg

app = QtGui.QApplication([])
view = pg.GraphicsView()
view.show()
view.resize(800,600)

class R(QtGui.QGraphicsWidget):
    # simple graphics widget that draws a rectangle around its geometry
    def boundingRect(self):
        return self.mapRectFromParent(self.geometry()).normalized()
    def paint(self, p, *args):
        p.setPen(pg.mkPen('y'))
        p.drawRect(self.boundingRect())

l = QtGui.QGraphicsGridLayout()
r1 = R()
r2 = R()
r3 = R()
r1.setLayout(l)
l.addItem(r2, 0, 0)
l.addItem(r3, 1, 0)

view.scene().addItem(r1)

In this example, calling l.setContentsMargins(...) has the expected effect, but calling r1.setContentsMargins(...) does not. The Qt docs suggest that the effect should have been the same, though: http://qt-project.org/doc/qt-4.8/qgraphicswidget.html#setContentsMargins

Answered By - Luke