wxPython simple GUI proving elusive

Question

I have been working on Python 3.8 and wxPython 4 (Phoenix) on GNU/Linux for a number of days and I am making very little progress. I need a very simple GUI, with a scrolled canvas taking the majority of a full-screen window and a scrolled panel holding about 4 lines of text below that. I want some margin around the canvas and panel. I would like to be able to the positioning automatically (and not absolutely). Problems I am encountering are 1) the scroll bars are not appearing, 2) I am using absolute positioning and I am not really sure the sizer I place is even functioning.

I have been hacking around, trying all sorts of variations. I have read over the API documentation for all calls I use. I have looked at demos and samples. I have looked at every book I can find on O'Reilly. I still feel like I am quite a bit in the dark on understanding the architecture of wxPython. I have developed many other GUI apps in Python in TkInter and Qt, and in other languages. So, I'm feeling pretty dense here.

Here is what the current app looks like:

And here is my current code:

#!/usr/bin/env python3.8 import wx class MainWindow(wx.Frame): def __init__(self, title): screen_x = wx.SystemSettings.GetMetric(wx.SYS_SCREEN_X) screen_y = wx.SystemSettings.GetMetric(wx.SYS_SCREEN_Y) size_value = wx.Size(screen_x, screen_y) wx.Frame.__init__(self, None, title=title, size=size_value) # why does this not work? # super(MainWindow, self).__init__(self, None, title=title, # size=size_value) canvas1 = wx.ScrolledCanvas(self, size=wx.Size(screen_x-30, 300), pos=wx.Point(15, 15)) canvas1.SetBackgroundColour('#cc20cc') canvas1.AlwaysShowScrollbars(True, True) canvas1.SetAutoLayout(1) canvas1.SetScrollbar(wx.VERTICAL, 0, 10, 100) canvas1.SetScrollbar(wx.HORIZONTAL, 0, 10, 100) canvas1.SetScrollRate(1, 1) # with open('/home/kbuchs/.emacs') as fp: # txt_value = fp.read() # txt = wx.StaticText(canvas1, label=txt_value) canvas2 = wx.ScrolledCanvas(self, size=wx.Size(screen_x-30, 1000), pos=wx.Point(15, 315)) canvas2.SetBackgroundColour('#d0d020') canvas2.AlwaysShowScrollbars(True, True) canvas2.SetAutoLayout(1) canvas2.SetScrollRate(1, 1) with open('/home/kbuchs/.bashrc') as fp: txt_value2 = fp.read() txt2 = wx.StaticText(canvas2, label=txt_value2) sizer = wx.BoxSizer(wx.VERTICAL) self.sizer = sizer sizer.Add(canvas1, wx.ID_ANY, wx.ALL, 20) sizer.Add(canvas2, wx.ID_ANY, wx.ALL, 40) self.Show() app = wx.App() MainWindow('Git Branch History') app.MainLoop()

Update 6/3 10:30 PM CDT. Here is my latest revision-attempt at the code after the example by Rolf of Saxony. It appears the two txt sections (if uncommented) are not getting written into the canvas/panels, but both are overlapping at the top of the frame. Also, still no scrolling.

#!/usr/bin/env python3.8 import wx import wx.lib.scrolledpanel as sp class MainWindow(wx.Frame): def __init__(self, title): screen_x = wx.SystemSettings.GetMetric(wx.SYS_SCREEN_X) screen_y = wx.SystemSettings.GetMetric(wx.SYS_SCREEN_Y) size_value = wx.Size(screen_x, screen_y) super(MainWindow, self).__init__(None, title=title, size=size_value) # canvas1 = wx.ScrolledCanvas(self, id=-1, canvas1 = sp.ScrolledPanel(self, id=-1, size=wx.Size(screen_x, screen_y-200)) # pos=wx.Point(15, 15)) canvas1.SetBackgroundColour('#ccffff') canvas1.AlwaysShowScrollbars(True, True) canvas1.SetAutoLayout(1) canvas1.SetupScrolling() with open('/home/kbuchs/.emacs') as fp: txt_value1 = fp.read() long_line = 900*'-' + '\n' # txt1 = wx.StaticText(canvas1, label=long_line+txt_value1) # txt1.SetBackgroundColour('#eeffff') # txt1Sizer = wx.BoxSizer(wx.VERTICAL) # txt1Sizer.Add(txt1, proportion=0, border=5) canvas1Sizer = wx.BoxSizer(wx.VERTICAL) canvas1Sizer.Add(canvas1, proportion=0, flag=wx.CENTER|wx.ALL|wx.EXPAND, border=5) # canvas1Sizer.Add(txt1Sizer, proportion=0) # canvas1Sizer.Add(txt1, proportion=0, flag=wx.ALL, border=5) # canvas2 = wx.ScrolledCanvas(self, id=-1, canvas2 = sp.ScrolledPanel(self, id=-1, size=wx.Size(screen_x, 200)) # pos=wx.Point(15, 315)) canvas2.SetBackgroundColour('#ffffcc') canvas2.AlwaysShowScrollbars(True, True) canvas2.SetAutoLayout(1) canvas2.SetupScrolling() with open('/home/kbuchs/.bashrc') as fp: txt_value2 = fp.read() # txt2 = wx.StaticText(canvas2, label=long_line+txt_value2) # txt2.SetBackgroundColour('#ffffee') canvas2Sizer = wx.BoxSizer(wx.VERTICAL) canvas2Sizer.Add(canvas2, proportion=0, flag=wx.CENTER|wx.ALL|wx.EXPAND, border=5) # canvas2Sizer.Add(txt2, proportion=0, flag=wx.CENTER|wx.ALL, border=20) sizer = wx.BoxSizer(wx.VERTICAL) self.sizer = sizer sizer.Add(canvas1Sizer, proportion=0, flag=wx.CENTER|wx.ALL|wx.EXPAND, border=5) sizer.Add(canvas2Sizer, proportion=0, flag=wx.CENTER|wx.ALL|wx.EXPAND, border=5) self.Show() app = wx.App() MainWindow('Git Branch History') app.MainLoop()

I haven't got time now but you need to assign the sizer i.e. self.SetSizer(sizer) before the Show. Direct positioning with a sizer may give an odd appearence. Sizers can drive you nuts at the beginning ;) — Rolf of Saxony
– Rolf of Saxony, Commented Jun 3, 2020 at 11:33

Rolf of Saxony · Accepted Answer · 2020-07-18 17:39:52Z

I'll take another stab at this, as you amended the question but did't make a comment, so I wasn't aware of it.
You seem to have a blindspot for SetSizer, mentioned twice in comments and used in my first answer.
It's like packing your suitcase and then going on holiday with your rucksack.

Here is is your second code example, amended.

import wx import wx.lib.scrolledpanel as sp class MainWindow(wx.Frame): def __init__(self, title): screen_x = wx.SystemSettings.GetMetric(wx.SYS_SCREEN_X) screen_y = wx.SystemSettings.GetMetric(wx.SYS_SCREEN_Y) size_value = wx.Size(screen_x, screen_y) super(MainWindow, self).__init__(None, title=title, size=size_value) canvas1 = sp.ScrolledPanel(self, id=-1,) canvas1.SetBackgroundColour('#ccffff') canvas1.SetupScrolling(scroll_x=True, scroll_y=True, rate_x=20, rate_y=20, scrollToTop=True, scrollIntoView=True) canvas1.AlwaysShowScrollbars(True, True) with open('tips.txt') as fp: txt_value1 = fp.read() long_line = 600*'y' + 'X\n' txt1 = wx.StaticText(canvas1, label=long_line+txt_value1) txt1.SetBackgroundColour('#eeffff') canvas1Sizer = wx.BoxSizer(wx.VERTICAL) canvas1Sizer.Add(txt1, proportion=0, flag=wx.ALL|wx.EXPAND, border=5) canvas2 = sp.ScrolledPanel(self, id=-1) canvas2.SetBackgroundColour('#ffffcc') canvas2.SetupScrolling(scroll_x=True, scroll_y=True, rate_x=20, rate_y=20, scrollToTop=True, scrollIntoView=True) canvas2.AlwaysShowScrollbars(True, True) with open('tips.txt') as fp: txt_value2 = fp.read() txt2 = wx.StaticText(canvas2, label=long_line+txt_value2) txt2.SetBackgroundColour('#ffffee') canvas2Sizer = wx.BoxSizer(wx.VERTICAL) canvas2Sizer.Add(txt2, proportion=0, flag=wx.ALL|wx.EXPAND, border=20) canvas1.SetSizer(canvas1Sizer) canvas2.SetSizer(canvas2Sizer) sizer = wx.BoxSizer(wx.VERTICAL) sizer.Add(canvas1, proportion=1, flag=wx.ALL|wx.EXPAND, border=5) sizer.Add(canvas2, proportion=1, flag=wx.ALL|wx.EXPAND, border=5) self.SetSizer(sizer) self.Show() app = wx.App() MainWindow('Git Branch History') app.MainLoop()

Thanks, Rolf. I was thinking you were referring to setting the sizer for the MainWindow, wx.Frame. For that, I had self.sizer = sizer, which I understand is exactly what self.SetSizer does. I see that I got myself confused with the separate sizers required for each canvas, because I actually added those sizers to the wx.Frame. But I see that I should have added the canvases to the frame and set the sizer for each canvas. I guess I had a mental image problem, thinking of a sizer as containing the things which it sizes (like Tk).
It is interesting how there is only one thing in each of those canvas sizers, the StaticText. Are those sizers even necessary under that case?

Rolf of Saxony · Accepted Answer · 2020-06-03 17:02:31Z

I'm going to throw your canvas away and replace it with TextCtrl, you could use whatever fits your requirements.
Hopefully, this will point you in the right direction, it has enough in there to show the way.

import wx class MainWindow(wx.Frame): def __init__(self, parent, title): screen_x = wx.SystemSettings.GetMetric(wx.SYS_SCREEN_X) screen_y = wx.SystemSettings.GetMetric(wx.SYS_SCREEN_Y) size_value = wx.Size(screen_x, screen_y) super(MainWindow, self).__init__(parent, title=title, size=size_value) #Define widgets tc1 = wx.TextCtrl(self, size=wx.Size(screen_x-30, 200), style= wx.TE_MULTILINE|wx.TE_PROCESS_ENTER|wx.TE_DONTWRAP|wx.TE_AUTO_URL) tc1.SetBackgroundColour('#cc2000') # Some Control buttons self.b1 = wx.Button(self, -1, "Button 1") self.b2 = wx.Button(self, -1, "Button 2") self.b3 = wx.Button(self, -1, "Quit") tc2 = wx.TextCtrl(self, size=wx.Size(screen_x-30, 1000), style= wx.TE_MULTILINE|wx.TE_PROCESS_ENTER|wx.TE_DONTWRAP) tc2.SetBackgroundColour('#d0d020') #Bind events to functions self.b3.Bind(wx.EVT_BUTTON, self.OnQuit) #Load initial data try: with open('tips.txt') as fp: txt_value2 = fp.read() except: txt_value2 = "tips.txt file not found" txt_value2 = txt_value2 * 20 tc1.AppendText("No data yet\n") tc1.AppendText("www.nodatayet.com\n") tc1.AppendText(" "*20) tc1.AppendText("X\n") tc2.write(txt_value2) #Define sizers sizer = wx.BoxSizer(wx.VERTICAL) button_sizer = wx.BoxSizer(wx.HORIZONTAL) #Populate sizers button_sizer.Add(self.b1) button_sizer.Add(self.b2) button_sizer.Add(self.b3) sizer.Add(tc1, proportion=0, flag=wx.ALL, border=20) sizer.Add(button_sizer, proportion=0, flag=wx.LEFT, border=40) sizer.Add(tc2, proportion=1, flag=wx.ALL, border=40) self.SetSizer(sizer) self.Show() def OnQuit(self, event): self.Destroy() app = wx.App() MainWindow(None,'Git Branch History') app.MainLoop()

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