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#!c:/python24/python

import wx

class Canvas(wx.Window):
    def __init__(self, parent, ID):
        wx.Window.__init__(self, parent, ID)
        self.SetBackgroundColour("White")
        self.color = "Black"
        self.thickness = 2
        self.pen = wx.Pen(self.color, self.thickness, wx.SOLID)
        self.brush = wx.Brush(wx.Colour( 80, 80, 255, 255))
        self.lines = [(-20,-20), (20,-20), (20,20), (-20,20), (-20,-20)]
        self.zoom = 1.0

        self.Bind(wx.EVT_MOTION, self.OnMotion)
        self.Bind(wx.EVT_MOUSEWHEEL, self.OnMotion)
        self.Bind(wx.EVT_SIZE, self.OnSize)
        self.Bind(wx.EVT_IDLE, self.OnIdle)
        self.Bind(wx.EVT_PAINT, self.OnPaint)

        self.SetSizeandOrigin()
        self.InitBuffer()

    def InitBuffer(self):

        self.buffer = wx.EmptyBitmap(self.width, self.height)
        dc = wx.BufferedDC(None, self.buffer)
        dc.SetMapMode(wx.MM_METRIC)

        # Drawing upside down (i.e. natural orientation)
        dc.SetAxisOrientation(True, True)

        # Original position is top left of window
        dc.SetDeviceOrigin(self.origin[0], self.origin[1])

        dc.SetBackground(wx.Brush(self.GetBackgroundColour()))
        dc.Clear()

        gc = wx.GraphicsContext.Create(dc)

        if self.lines: 
            self.DrawLines(gc)

        # Prevent redraw in OnIdle 
        self.reInitBuffer = False

    def OnPaint(self, event):
        # For double buffered drawing; content of self.buffer is blit here to the DC
        dc = wx.BufferedPaintDC(self, self.buffer)

    def DrawLines(self, gc):
        path = gc.CreatePath()
        path.MoveToPoint(self.lines[0])   # Move to start point of airfoil
        for index, coord in enumerate(self.lines):
            #if index == 0: pass
            path.AddLineToPoint(coord)
        gc.SetPen(self.pen)
        gc.SetBrush(self.brush)
        gc.Scale(self.zoom, self.zoom)
        gc.DrawPath(path)

    def OnMotion(self, event):
        # Drag
        if event.Dragging() and event.LeftIsDown() and not event.m_controlDown:
            actPos = event.GetPositionTuple()
            xact = actPos[0]
            yact = actPos[1]
            xold = self.pos[0]
            yold = self.pos[1]
            vx = xact - xold
            vy = yact - yold
            self.origin = (self.origin[0] + vx, self.origin[1] + vy)
            self.pos = actPos
            self.InitBuffer()
            self.Refresh(False)
        # Zoom
        elif event.GetWheelRotation():
            self.zoom = self.zoom - event.GetWheelRotation()/float(self.height)    # Change zoom factor
            self.InitBuffer()
            self.Refresh(False)
        else:
            self.pos = event.GetPositionTuple()   # Initialize for dragging

        event.Skip()   # ???

    def OnSize(self, event):
        self.width, self.height = self.GetClientSize()
        self.SetSizeandOrigin(0)
        self.reInitBuffer = True  # Redraw is automatically performed in OnIdle

    def OnIdle(self, event):
        if self.reInitBuffer:
            self.InitBuffer()
            self.Refresh(False)   #  generates EVT_PAINT; False means background not erased

    def SetSizeandOrigin(self, fit=0):
        self.width, self.height = self.GetClientSize()
        if fit == 0:
            or_x = 0.5*self.width    # to be changed for all
            or_y = 0.5*self.height   # to be changed for all
            self.zoom = 1.0

        self.origin = (or_x, or_y)

class SketchFrame(wx.Frame):
    def __init__(self, parent):
        wx.Frame.__init__(self, parent, -1, "Test",
                size=(800,600))
        self.sketch = Canvas(self, -1)

if __name__ == '__main__':
    app = wx.App(redirect=False)
    frame = SketchFrame(None)
    frame.Show(True)
    app.MainLoop()