尝试在wXPython中使滚动窗口成为可拖动的子代

Question

I am trying to create children whose parent is a ScrolledWindow and intercept mouse drags to allow repositioning children absolutely within the client area of the parent. I want the client virtual scrolled area to expand as needed to accommodate the position of the children (so a larger-than-window graph gets scrolled). The dragging seems to be problematic since it wants to move by the corners all the time trying to drag an object left or up is problematic. It's also not scrolling when the widgets go beyond the current window boundaries. In the driver using this code all the ConceptNode widgets specify the SemNetWidget as their parent. I'm not using using a sizer since the absolute positioning (dragged positions) of the children should be maintained. I don't suppose wxPython provides a way to position objects by centers rather than by corners as it would make some of this much easier to code:

class SemNetWidget(wx.ScrolledWindow):
    def __init__(self,edit,*args,**kwargs):
        self.editor=edit
        super(SemNetWidget,self).__init__(*args,**kwargs)
        self.SetScrollbars(1,1,1,1)

class ConceptNode(wx.StaticText):
    count=0
    def __init__(self,nm,*args,**kwargs):
        if not kwargs.has_key("style"):
            kwargs["style"]=0
        kwargs["style"]=wx.SIMPLE_BORDER|wx.ALIGN_CENTRE
        super(ConceptNode,self).__init__(*args,**kwargs)
        par=args[0]
        self.nm=nm
        self.mcap=False
        self.par=par
        self.SetLabel(" %s " % self.nm)
        self.Move((0,15*self.count)) # so new nodes don't overlap
        self.par.FitInside()
        self.Bind(wx.EVT_MOUSE_EVENTS,self.onDrag) 
        self.Bind(wx.EVT_MOTION,self.onDrag)
        self.Bind(wx.EVT_MOUSE_CAPTURE_LOST,self.onUncap) 
        ConceptNode.count+=1
    def onUncap(self,evt):
        self.mcap=False
        self.drag=None
    def onDrag(self,evt):
        if evt.Dragging() and self.drag is not None:
            #cdc=wx.ClientDC(self)
            #self.PrepareDC(cdc)
            #pos=list(evt.GetLogicalPosition(cdc))
            pos=evt.GetPosition()
            dx=pos[0]-self.drag['x']
            dy=pos[1]-self.drag['y']
            self.SetPosition((self.drag['ox']+dx,
                              self.drag['oy']+dy),
                            wx.SIZE_ALLOW_MINUS_ONE)
        if evt.LeftDown():
            pos=evt.GetPosition()
            opos=self.GetPosition()
            self.drag={'x':pos[0],'y':pos[1],
                       'ox':opos[0],'oy':opos[1]}
            self.CaptureMouse()
            self.mcap=True
            evt.Skip()
        if evt.LeftUp():
            self.drag=None
            if self.mcap:
                self.ReleaseMouse()

Driver:

if __name__=="__main__":
    app=wx.App()
    window=wx.Frame(None,wx.ID_ANY)
    frame=SemNetWidget(None,window) # None:=No editor object
    c1=ConceptNode("Concept1",frame)
    c2=ConceptNode("Concept2",frame)
    window.Show()
    app.MainLoop()

Answer 1

You should create a small runnable example that demonstrates what you're doing: http://wiki.wxpython.org/MakingSampleApps

In the meantime, if you're just moving around objects that you drew yourself, then you might find the DragImage demo useful. It can be found in the wxPython demo. Otherwise, I would recommend asking on the official wxPython mailing list / Google group as there are a lot of experienced wxPython developers there: https://groups.google.com/forum/?pli=1#!forum/wxpython-users