Open another wx.python frame cause the main UI to be blocked - python-3.x

Question

I am trying to open another wx frame from a main frame UI. I followed the example shown here: https://wiki.wxpython.org/CallAfter but my main UI is still blocked.
Here is the event listener on the main UI:
def testShowGUI(self):
# This process is a long one
# It uses the vtk to read point cloud file and reconstruct the surface
file = "cache/d9c5e8ef-7b7f-485e-8fc8-23098c32afcb.ply"
reader = vtk.vtkPLYReader()
reader.SetFileName(file)
reader.Update()
delaunay = vtk.vtkDelaunay2D()
delaunay.SetAlpha(0.1)
delaunay.SetTolerance(0.0001)
delaunay.SetOffset(1.25)
delaunay.BoundingTriangulationOff()
delaunay.SetInputData(reader.GetOutput())
delaunay.Update()
#Once finish reading and processing the point cloud, pass to the next function for rendering
wx.CallAfter(self.AfterProcess, delaunay)
def AfterProcess(self, data):
meshVisGui = MesVisGUI.MeshVisGui(data)
meshVisGui.Show()
def OnEnter(self, event):
#Event listener when user click on Enter button
my_thread = threading.Thread(target=self.testShowGUI)
my_thread.start()
The code for the separate frame is as below:
class MeshVisGui(wx.Frame):
SPACING = 4
def __init__(self, delaunay, parent=None):
self.delaunayData = delaunay
self.title = "Mesh Visualization"
wx.Frame.__init__(self, None, -1, self.title)
self.Initialize()
def Initialize(self):
self.panel = wx.Panel(self, -1, size=(600, 400), style=wx.BORDER_RAISED)
self.widget3d = wxVTKRenderWindowInteractor(self.panel, -1)
self.widget3d.Enable()
self.render = vtk.vtkRenderer()
self.render.SetBackground(params.BackgroundColor)
self.widget3d.GetRenderWindow().AddRenderer(self.render)
self.interactor = self.widget3d.GetRenderWindow().GetInteractor()
self.interactor.GetInteractorStyle().SetCurrentStyleToTrackballCamera()
self.axesWidget = utils.createAxes(self.interactor)
self.meshActor = utils.build_actor(self.delaunayData)
self.render.AddActor(self.meshActor)
self.render.ResetCamera()
box = wx.BoxSizer(wx.VERTICAL)
box.Add(self.widget3d, 1, wx.EXPAND, self.SPACING)
self.panel.SetSizer(box)
self.Layout()
However, on my main UI, it is still showing a spinning icon and block the UI while it is trying to process the point cloud data. Can someone help me spot what I have done wrong?
Wxpython version: 4.0.1
Python version: 3.6.5

Answer 1

Following on from Mike Driscoll's answer and comment, here is a sample of a threaded task running from another panel.
The thread reports back to the 2nd panel (it's parent) using an event. This allows a progress bar to be updated.
The 2nd panel includes a "Cancel" option for the threaded task, whilst the main frame has a button to test if it is not frozen.
The use of wx.GetApp().Yield() may be slightly old fashioned but I have always found it to be reliable.
import time
import wx
from threading import Thread
import wx.lib.newevent
progress_event, EVT_PROGRESS_EVENT = wx.lib.newevent.NewEvent()
class ThreadFrame(wx.Frame):
def __init__(self, title, parent=None):
wx.Frame.__init__(self, parent=parent, title=title)
panel = wx.Panel(self)
self.btn = wx.Button(panel,label='Stop Long running process', size=(200,30), pos=(10,10))
self.btn.Bind(wx.EVT_BUTTON, self.OnExit)
self.progress = wx.Gauge(panel,size=(300,10), pos=(10,50), range=300)
#Bind to the progress event issued by the thread
self.Bind(EVT_PROGRESS_EVENT, self.OnProgress)
#Bind to Exit on frame close
self.Bind(wx.EVT_CLOSE, self.OnExit)
self.Show()
self.mythread = TestThread(self)
#Enable the GUI to be responsive by briefly returning control to the main App
while self.mythread.isAlive():
time.sleep(0.1)
wx.GetApp().Yield()
continue
try:
self.OnExit(None)
except:
pass
def OnProgress(self, event):
self.progress.SetValue(event.count)
#or for indeterminate progress
#self.progress.Pulse()
def OnExit(self, event):
if self.mythread.isAlive():
self.mythread.terminate() # Shutdown the thread
self.mythread.join() # Wait for it to finish
self.Destroy()
class TestThread(Thread):
def __init__(self,parent_target):
Thread.__init__(self)
self.parent = parent_target
self.stopthread = False
self.time = time.time()
self.start() # start the thread
def run(self):
# A loop that will run for 5 minutes then terminate
while self.stopthread == False:
curr_loop = int(time.time() - self.time)
if curr_loop < 300:
time.sleep(1)
evt = progress_event(count=curr_loop)
#Send back current count for the progress bar
try:
wx.PostEvent(self.parent, evt)
except: # The parent frame has probably been destroyed
self.terminate()
else:
self.terminate()
def terminate(self):
self.stopthread = True
class MyPanel(wx.Panel):
def __init__(self, parent):
wx.Panel.__init__(self, parent)
self.text_count = 0
self.parent=parent
btn = wx.Button(self, wx.ID_ANY, label='Start Long running process', size=(200,30), pos=(10,10))
btn.Bind(wx.EVT_BUTTON, self.Thread_Frame)
btn2 = wx.Button(self, wx.ID_ANY, label='Is the GUI still active?', size=(200,30), pos=(10,50))
btn2.Bind(wx.EVT_BUTTON, self.AddText)
self.txt = wx.TextCtrl(self, wx.ID_ANY, style= wx.TE_MULTILINE, pos=(10,90),size=(400,100))
def Thread_Frame(self, event):
frame = ThreadFrame(title='Threaded Task', parent=self.parent)
def AddText(self,event):
self.text_count += 1
txt = self.txt.GetValue()
txt += "More text " + str(self.text_count)+"\n"
self.txt.SetValue(txt)
class MainFrame(wx.Frame):
def __init__(self):
wx.Frame.__init__(self, None, title='Main Frame', size=(600,400))
panel = MyPanel(self)
self.Show()
if __name__ == '__main__':
app = wx.App(False)
frame = MainFrame()
app.MainLoop()

Answer 2

You do not need threads to open new frames / windows in your wxPython application. You just need to create a sub-class of wx.Frame to hold the code of your other frame. Then from your main application's frame, you can instantiate the other frame and show it. You use the same concept when you create a wx.Dialog or a wx.MessageDialog.
Here is a simple example:
import wx
class OtherFrame(wx.Frame):
"""
Class used for creating frames other than the main one
"""
def __init__(self, title, parent=None):
wx.Frame.__init__(self, parent=parent, title=title)
self.Show()
class MyPanel(wx.Panel):
def __init__(self, parent):
wx.Panel.__init__(self, parent)
btn = wx.Button(self, label='Create New Frame')
btn.Bind(wx.EVT_BUTTON, self.on_new_frame)
def on_new_frame(self, event):
frame = OtherFrame(title='SubFrame',
parent=wx.GetTopLevelParent(self))
class MainFrame(wx.Frame):
def __init__(self):
wx.Frame.__init__(self, None, title='Main Frame')
panel = MyPanel(self)
self.Show()
if __name__ == '__main__':
app = wx.App(False)
frame = MainFrame()
app.MainLoop()
In this example, I set the other frame's parent to the MainFrame instance by using wx.GetTopLevelParent(self). The benefit of setting a parent for the sub-frames is that if I close the main frame, it will cause the other frames to also be closed.