I am creating a small drawing application from a python book, "wxPython in Action", and it uses self.GetClientSize() to get the size of a window. For some reason this is return (0, 0) for me instead of the expected value (800, 600).
The program crashes when wx.EmptyBitmap is called with 0, 0 as its parameters. If I put wx.EmptyBitmap(800, 600) the entire program runs fine, minus resizing.
Here is the relevant method
def InitBuffer(self):
size = self.GetClientSizeTuple()
print size
sys.exit(1)
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
And this is the complete code
#!/usr/bin/arch -i386 /usr/bin/python2.6 -tt
import sys
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_SIZE, self.OnSize)
self.Bind(wx.EVT_MOTION, self.OnMotion)
self.Bind(wx.EVT_IDLE, self.OnIdle)
self.Bind(wx.EVT_PAINT, self.OnPaint)
def InitBuffer(self):
size = self.GetClientSizeTuple()
print size
sys.exit(1)
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
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(Fa开发者_如何转开发lse)
def OnPaint(self, event):
dc = wx.BufferedPaintDC(self, self.buffer)
def DrawLines(self, dc):
for (colour, thickness, line) in self.lines:
pen = wx.Pen(colour, thickness, wx.SOLID)
dc.SetPen(pen)
for coord in line:
dc.DrawLine(*coord)
def SetColor(self, color):
self.color = color
self.pen = wx.Pen(self.color, self.thickness, wx.SOLID)
def GetColor(self):
return self.color
def SetThickness(self, thickness):
self.thickness = thickness
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)
def main():
app = wx.PySimpleApp()
frame = SketchFrame(None)
frame.Show(True)
app.MainLoop()
if __name__ == '__main__':
main()
It's because you're calling GetSize
in the __init__()
method - the window isn't fully created until this method has completed. Thus, it hasn't has its width and height set properly.
You could use wx.CallAfter/CallLater to postpone the calling of this function until window creation has fully completed.
I don't know if there is a better solution, but the problem is that when the object was being initialized it didn't have a parent yet, so it didn't know what size it should be. Thus it was width 0 and height 0. However, it needed to initialize the buffer. What I did to fix this was
if size == (0, 0):
size.width = 1
size.height = 1
Once it is added to the frame it gets a new size and the buffer is resized. So I guess that works!
I suppose another solution would be to pass a size parameter to the init method, but i'd prefer not to have to do that if it is not required.
Please post other solutions if you have them =)
精彩评论