Question

I have a PyQt4 application with embedded matplotlib figures in it.

As you see I have added the navigation toolbar as a widget. I would like to be able to update the plot on the right based on the data displayed on the plot on the left. It seems the easiest way would be to hijack the info contained in whatever does the “zooming”. Or at least know when a zoom has occurred so I can recalculate and redraw on the right. Anyone have a good approach to this (re-implementing from the pick_event level would be a last resort)?

Answer 1

The best way I came up with is creating a custom navigation toolbar with NavigationToolbar as the parent. Then I just added a signal to the custom version and overrode the draw method. In this way I could call the original draw method and emit my signal with whatever info I needed from the NavigationToolbar data structure.

class NavigationToolbarCustom(NavigationToolbar):
zoom_changed = pyqtSignal(float, float, name='zoomChanged')
def __init__(self, canvas, parent):
    NavigationToolbar.__init__(self, canvas, parent)
    #super(NavigationToolbarCustom, self).__init__(self, canvas, parent)
def draw(self):
    super(NavigationToolbarCustom,self).draw()
    if self._xypress == None:
         home_view = self._views.home()
         Xmin,Xmax = home_view[0][0:2]
    else:
        lastx, lasty, a, ind, lim, trans = self._xypress[0]
        Xmin,Xmax=a.get_xlim()
    self.zoom_changed.emit(Xmin,Xmax)