import wx

class SketchWindow(wx.Window):

    def __init__(self, parent, ID):

        wx.Window.__init__(self, parent, ID)

        self.SetBackgroundColour("White")

        self.color = "Black"

        self.thickness = 1

        self.pen = wx.Pen(self.color, self.thickness, wx.SOLID)

        self.lines = []

        self.curLine = []

        self.pos = (0, 0)

        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_SIZE, self.OnSize)

        self.Bind(wx.EVT_IDLE, self.OnIdle)

        self.Bind(wx.EVT_PAINT, self.OnPaint)

    def InitBuffer(self):

        size = self.GetClientSize()

        self.buffer = wx.EmptyBitmap(size.width, size.height)

        dc = wx.BufferedDC(None, self.buffer)

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

        dc.Clear()

        self.DrawLines(dc)

        self.reInitBuffer = False

    def GetLinesData(self):

        return self.lines[:]

    def SetLinesData(self, lines):

        self.lines = lines[:]

        self.InitBuffer()

        self.Refresh()

    def OnLeftDown(self, event):

        self.curLine = []

        self.pos = event.GetPositionTuple()

        self.CaptureMouse()

    def OnLeftUp(self, event):

        if self.HasCapture():

            self.lines.append((self.color,

                               self.thickness,

                               self.curLine))

            self.curLine = []

            self.ReleaseMouse()

    def OnMotion(self, event):

        if event.Dragging() and event.LeftIsDown():

            dc = wx.BufferedDC(wx.ClientDC(self), self.buffer)

            self.drawMotion(dc, event)

        event.Skip()

    def drawMotion(self, dc, event):

        dc.SetPen(self.pen)

        newPos = event.GetPositionTuple()

        coords = self.pos + newPos

    print coords

    print "sss"

        self.curLine.append(coords)

        dc.DrawLine(*coords)

        self.pos = newPos

    def OnSize(self, event):

        self.reInitBuffer = True

    def OnIdle(self, event):

        if self.reInitBuffer:

            self.InitBuffer()

            self.Refresh(False)

    def OnPaint(self, event):

    dc = wx.BufferedPaintDC(self, self.buffer) # 估计基本上不起作用，但是Python要求在OnPaint里必须创建一个dc

    print "fffff" # 只有被遮住后重新显现的时候才打印，否则移动窗口不会触发这里，甚至往下移动进一步遮住也不会触发这里

    def DrawLines(self, dc):

        for colour, thickness, line in self.lines:

            pen = wx.Pen(colour, thickness, wx.SOLID)

            dc.SetPen(pen)

            for coords in line:

                dc.DrawLine(*coords)

    def SetColor(self, color):

        self.color = color

        self.pen = wx.Pen(self.color, self.thickness, wx.SOLID)

    def SetThickness(self, num):

        self.thickness = num

        self.pen = wx.Pen(self.color, self.thickness, wx.SOLID)

class SketchFrame(wx.Frame):

    def __init__(self, parent):

        wx.Frame.__init__(self, parent, -1, "Sketch Frame",

                size=(800,600))

        self.sketch = SketchWindow(self, -1)

if __name__ == '__main__':

    app = wx.PySimpleApp()

    frame = SketchFrame(None)

    frame.Show(True)

    app.MainLoop()