All:

I'm confused.  I've set up a rectangular region program that will draw a rectangle and dynam
ically size it when the user drags the mouse.  This is going to be used for viewing only ima
ges within the window.  I want the pen to be bright red.  And I want it to be that way ALL t
he time!  For some reason, when I change the background color of my brush to something OTHER
 than black, I get a different color.  Why?

Here's the code in it's entirety:

import wx

class RectWidget(wx.Window):
    def __init__(self,parent,ID,size):
        wx.Window.__init__(self,parent,ID)
        # mouse selection start point
        self.m_stpoint=wx.Point(0,0)
        # mouse selection end point
        self.m_endpoint=wx.Point(0,0)
        # mouse selection cache point
        self.m_savepoint=wx.Point(0,0)
        self.SetClientSize(size)
        self.InitBuffer()
        
        self.Bind(wx.EVT_LEFT_DOWN, self.OnLeftDown)
        self.Bind(wx.EVT_LEFT_UP, self.OnLeftUp)
        self.Bind(wx.EVT_MOTION, self.OnMotion)
        self.Bind(wx.EVT_PAINT, self.OnPaint)
        

    def InitBuffer(self):
        size = self.GetClientSize()
        self.buffer = wx.EmptyBitmap(size.width, size.height)
        dc = wx.BufferedDC(wx.ClientDC(self),self.buffer)
        dc.SetBackground(wx.Brush("Black"))     <<<<<<<<<<<<<<<<<<< ORIGINAL BRUSH COLOR (ba
ckground)
        dc.Clear()
        
        
    def OnLeftDown(self, event):
        # Left mouse button down, change cursor to
        # something else to denote event capture
        self.m_stpoint = event.GetPosition()
        cur = wx.StockCursor(wx.CURSOR_CROSS)  
        self.SetCursor(cur)
        
        # invalidate current canvas
        self.InitBuffer()
        self.Refresh()
           
        # cache current position
        self.m_savepoint = self.m_stpoint
        self.CaptureMouse()
        
    def OnMotion(self,event):
        if event.Dragging() and event.LeftIsDown():
            # get device context of canvas
            dc= wx.BufferedDC(wx.ClientDC(self),self.buffer)
            
            # Set logical function to XOR for rubberbanding
            dc.SetLogicalFunction(wx.XOR)
            
            # Set dc brush and pen
            # Here I set brush and pen to white and grey respectively
            # You can set it to your own choices
            
            # The brush setting is not really needed since we
            # dont do any filling of the dc. It is set just for 
            # the sake of completion.
            wbrush = wx.Brush("White", wx.TRANSPARENT)
            wpen = wx.Pen("Red", 1, wx.SOLID)                        <<< NOT WORKING WHEN or
iginal Brush is something other than black!
            dc.SetBrush(wbrush)
            dc.SetPen(wpen)
            self.drawMotion(dc,event)
               
            
    def drawMotion(self,dc,event):
        # reset dc bounding box
        dc.ResetBoundingBox()
        dc.BeginDrawing()
        w = (self.m_savepoint.x - self.m_stpoint.x)
        h = (self.m_savepoint.y - self.m_stpoint.y)
        
        # To erase previous rectangle
        dc.DrawRectangle(self.m_stpoint.x, self.m_stpoint.y, w, h)
        
        # Draw new rectangle
        self.m_endpoint =  event.GetPosition()
        
        w = (self.m_endpoint.x - self.m_stpoint.x)
        h = (self.m_endpoint.y - self.m_stpoint.y)
        
        # Set clipping region to rectangle corners
        dc.SetClippingRegion(self.m_stpoint.x, self.m_stpoint.y, w,h)
        dc.DrawRectangle(self.m_stpoint.x, self.m_stpoint.y, w, h) 
        dc.EndDrawing()
       
        self.m_savepoint = self.m_endpoint # cache current endpoint

    def OnLeftUp(self,event):
        if self.HasCapture():
            # User released left button, change cursor back
            self.SetCursor(wx.StockCursor(wx.CURSOR_ARROW))       
            self.ReleaseMouse()
   
    def OnPaint(self,event):
        dc = wx.BufferedPaintDC(self,self.buffer)
             
class ToolbarFrame(wx.Frame):
    def __init__(self,parent,id):
        wx.Frame.__init__(self,parent,id, 'Render Region', size=(640,480))
        statusBar = self.CreateStatusBar()
        self.region = RectWidget(self,-1,size=(640,480))

if __name__ == '__main__':
    app = wx.PySimpleApp()
    frame = ToolbarFrame(parent=None,id=-1)
    frame.Show()
    app.MainLoop()



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