wxPython button widget won't move

Question

I'm building a simple webcam program to take pictures. Right now, I'm completing the GUI, and my wxPython button won't move even when it's explicitly placed. I've tried following the basic wxPython tutorial and it's not working. Could it be that my bitmap is not 'on' the panel?

Here's my code:

import wx
import cv2

class webcamWindow(wx.Panel):

    def __init__(self, parent, camera, fps=10):
        wx.Panel.__init__(self, parent)
        panel = wx.Panel(self, -1)

        wx.Button(panel, -1, "Capture", (210,660))

        self.camera = camera
        ret_value, frame = self.camera.read()
        height, width = frame.shape[:2]
        parent.SetSize((width, (height+75)))

        frame = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
        frame = cv2.flip(frame, 1)
        self.bmp = wx.BitmapFromBuffer(width, height, frame)

        self.timer = wx.Timer(self)
        self.timer.Start(1000./fps)

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

    def OnPaint(self, e):
        dc = wx.BufferedPaintDC(self)
        dc.DrawBitmap(self.bmp, 0, 0)
    def NextFrame(self, e):
        ret_value, frame = self.camera.read()
        if ret_value:
            frame = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
            frame = cv2.flip(frame, 1)
            self.bmp.CopyFromBuffer(frame)
            self.Refresh()

camera = cv2.VideoCapture(0)

app = wx.App()
frame = wx.Frame(None, -1, "Webcam")
cap = webcamWindow(frame, camera)
frame.Show()
app.MainLoop()

Answer 1

I create Panel only for webcam image and then I use it in frame with Button

import wx
import cv2

#---------------------------------------------------------------------- 

class webcamPanel(wx.Panel):

    def __init__(self, parent, camera, fps=10):
        wx.Panel.__init__(self, parent)

        self.camera = camera

        ret_value, frame = self.camera.read()
        height, width = frame.shape[:2]

        # resize panel with camera image
        self.SetSize( (width, height) )

        # resize main window
        self.GetParent().GetParent().SetSize( (width, height+75) )

        frame = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
        frame = cv2.flip(frame, 1)
        self.bmp = wx.BitmapFromBuffer(width, height, frame)

        self.timer = wx.Timer(self)
        self.timer.Start(1000./fps)

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

    def OnPaint(self, e):
        dc = wx.BufferedPaintDC(self)
        dc.DrawBitmap(self.bmp, 0, 0)

    def NextFrame(self, e):
        ret_value, frame = self.camera.read()
        if ret_value:
            frame = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
            frame = cv2.flip(frame, 1)
            self.bmp.CopyFromBuffer(frame)
            self.Refresh()

#---------------------------------------------------------------------- 

class webcamWindow(wx.Frame):

    def __init__(self, camera, fps=10):
        wx.Frame.__init__(self, None)

        self.panel = wx.Panel(self, -1)

        # add panel with webcam image
        self.webcampanel = webcamPanel(self.panel, camera)

        # get size of webcam panel
        webcampanelsize = self.webcampanel.GetSize()

        # put button below webcam panel
        self.but = wx.Button(self.panel, label="Capture", pos=(0, webcampanelsize.height), size=(webcampanelsize.width,75))

#----------------------------------------------------------------------

camera = cv2.VideoCapture(0)

app = wx.App()
cap = webcamWindow(camera)
cap.Show()
app.MainLoop()

If you use some layout manager in Frame you will not have to calculate Button position.

In place of wx.Panel you could use wx.Window or wx.Control. See: Class hierarchy