validation in feet to meters

tk_first_steps/feet.py

@@ -1,6 +1,28 @@
 from tkinter import *
 from tkinter import ttk
 
+status = 1
+
+def switch_status(newS: int = None):
+    global status
+    if not newS:
+        if status == 1:
+            status = 2
+        else:
+            status = 1
+    else:
+        status = newS
+    update_statusbar()
+
+def update_statusbar():
+    global status
+    if status == 1:
+        frame_statusbar['style'] = 'aFrame.TFrame'
+    elif status == 2:
+        frame_statusbar['style'] = 'bFrame.TFrame'
+    else:
+        frame_statusbar['style'] = 'bFrame.TFrame'
+
 def calculate(*args):
     try:
         stringvalue = feet.get()
@@ -9,24 +31,42 @@ def calculate(*args):
         m_value = 0.3048 * value
         m_value = round(m_value, 2)
         meters.set(m_value)
+        switch_status(2)
     except ValueError:
         pass
     return True
 
+def check_entry(what):
+    switch_status(1)
+    if what == "":
+        # Nichts eingegeben
+        return True
+    else:
+        try:
+            # DEBUG
+            print(what)
+            float(what)
+            return True
+        except ValueError:
+            return False
+
 # Hauptfenster
 root = Tk()
 root.title("Feet to Meters")
+check_entry_wrapper = root.register(check_entry)
 
 # Rahmen im Hauptfenster (aus ttk für Farbanpassung)
 mainframe = ttk.Frame(root, padding = "3 3 12 12")
 
-mainframe.grid(column = 0, row = 0, sticky = (N,W,E,S))
+mainframe.grid(column = 0, row = 0, sticky = NW)
 root.columnconfigure(0, weight = 1)
 root.rowconfigure(0, weight = 1)
 
 # Eingabefeld für Länge in feet
 feet = StringVar()
-feet_entry = ttk.Entry(mainframe, width = 7, textvariable = feet)
+feet_entry = ttk.Entry(mainframe, width = 7, textvariable = feet,
+                       validatecommand = (check_entry_wrapper, '%P'),
+                       validate = 'key')
 feet_entry.grid(column = 2, row = 1, sticky = (W, E))
 
 # Einheit-Label für Eingabefeld der Länge in feet
@@ -42,7 +82,7 @@ ttk.Label(mainframe, text = "Meter").grid(column = 3, row = 2, sticky = W)
 meters = StringVar()
 meters_entry = ttk.Entry(mainframe, width = 7, textvariable = meters)
 meters_entry.grid(column = 2, row = 2, sticky = (W,E))
-meters_entry.configure(state = 'disabled') # keine Eingabe, aber selektierbar
+meters_entry.configure(state = 'readonly') # keine Eingabe, aber selektierbar
 
 # Button für Berechnung
 
@@ -53,6 +93,18 @@ button_calc.grid(column = 3, row = 3, sticky = W)
 for child in mainframe.winfo_children():
     child.grid_configure(padx = 5, pady = 5)
 
+# Statusbar
+s = ttk.Style()
+s.configure('aFrame.TFrame', background = "yellow")
+s.configure('bFrame.TFrame', background = "green")
+s.configure('cFrame.TFrame', background = "red")
+frame_statusbar = ttk.Frame(root)
+frame_statusbar['relief'] = 'sunken'
+frame_statusbar['height'] = 12
+frame_statusbar['style'] = 'aFrame.TFrame'
+frame_statusbar.grid_propagate(0) # Feste Größe an Grid-Packer weitergeben
+frame_statusbar.grid(column = 0, row = 1, sticky = W+S+E)
+
 # Setze Fokus in Eingabefeld
 feet_entry.focus()