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POPanel doesn't fully refresh when using a custom background in wxPython
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copied!<p>Here's some sample code:</p> <pre><code>import wx class MainPanel(wx.Panel): p1 = None p2 = None def __init__(self, parent): wx.Panel.__init__(self, parent=parent) self.frame = parent #self.SetBackgroundStyle(wx.BG_STYLE_CUSTOM) #self.bg = wx.Bitmap("2.jpg") self.Bind(wx.EVT_MOTION, self.OnMouseMove) self.Bind(wx.EVT_LEFT_DOWN, self.OnMouseDown) self.Bind(wx.EVT_PAINT, self.OnPaint) self.SetCursor(wx.StockCursor(wx.CURSOR_CROSS)) def OnMouseMove(self, event): if event.Dragging() and event.LeftIsDown(): self.p2 = event.GetPosition() self.Refresh() def OnMouseDown(self, event): self.p1 = event.GetPosition() def OnPaint(self, event): if self.p1 is None or self.p2 is None: return dc = wx.PaintDC(self) dc.SetPen(wx.Pen('red', 3, wx.LONG_DASH)) dc.SetBrush(wx.Brush(wx.Color(0, 0, 0), wx.SOLID)) dc.DrawRectangle(self.p1.x, self.p1.y, self.p2.x - self.p1.x, self.p2.y - self.p1.y) class MainFrame(wx.Frame): def __init__(self): wx.Frame.__init__(self, None, size=(600,450)) panel = MainPanel(self) self.Center() class Main(wx.App): def __init__(self, redirect=False, filename=None): wx.App.__init__(self, redirect, filename) dlg = MainFrame() dlg.Show() if __name__ == "__main__": app = Main() app.MainLoop() </code></pre> <p>The two offending lines are:</p> <pre><code> #self.SetBackgroundStyle(wx.BG_STYLE_CUSTOM) #self.bg = wx.Bitmap("2.jpg") </code></pre> <p>If you run the code like that, you're able to draw a rectangle on the panel. If you start a new rectangle, the old one disappears, because the panel is refreshing. </p> <p>However, if you uncomment those two lines, when you draw a rectangle, it stays there. You can have infinite number of rectangles. If I use dc.Clear(), the background disappears and reloading the background makes the application slow and it flickers.</p> <p>How do I make the panel fully refresh while using a custom background?</p> <p>By the way, the background image doesn't load with this code, but the behavior is the same.</p> <p><strong>EDIT:</strong> I found a workaround to the flickering caused by using dc.Clear() and reloading the background. Setting double buffering on the panel to true solves the flickering:</p> <pre><code>self.SetDoubleBuffered(True) </code></pre> <p>I will use that, but I'll leave the question open in case someone knows the answer to the initial problem.</p>

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