Question

import wx

class TestDraw(wx.Panel):
    def __init__(self,parent=None,id=-1):
        wx.Panel.__init__(self,parent,id)
        self.SetBackgroundColour("#FFFFFF")
        self.Bind(wx.EVT_PAINT,self.onPaint)
    def onPaint(self, event):
        event.Skip()

        dc=wx.PaintDC(self)
        dc.BeginDrawing()
        width=dc.GetSize()[0]
        height=dc.GetSize()[1]
        if height<width:
            self.drawTestRects(dc)
        else:
            dc.Clear()
        dc.EndDrawing()

    def drawTestRects(self,dc):
        dc.SetBrush(wx.Brush("#000000",style=wx.SOLID))
        dc.DrawRectangle(50,50,50,50)
        dc.DrawRectangle(100,100,100,100)

class TestFrame(wx.Frame):
    def __init__(self, parent, title):
        wx.Frame.__init__(self, parent, title=title, size=(640,480))
        self.mainPanel=TestDraw(self,-1)

        self.Show(True)


app = wx.App(False)
frame = TestFrame(None,"Test App")
app.MainLoop()

This code should draw the test rectangles only when the height is less than the width, and otherwise the window should remain clear. However, if you mess with resizing the window, the panel isn’t actually redrawn unless it is moved off the window. What am I doing wrong?

Answer 1

You can bind a method to handle wx.EVT_SIZE or the panel and invalidate it there. Alternatively simply use the wx.FULL_REPAINT_ON_RESIZE for the panel.