Prior to listbox refactor.

README.md

@@ -1256,7 +1256,7 @@ Constructor mandatory positional args:
 
 Mandatory keyword only argument:
  * `elements` A list or tuple of strings to display. Must have at least one
- entry.
+ entry. See below for an alternative way to use the `Dropdown`.
 
 Optional keyword only arguments:
  * `width=None` Control width in pixels. By default this is calculated to
@@ -1298,6 +1298,19 @@ The callback's first argument is the dropdown instance followed by any args
 specified to the constructor. The currently selected item may be retrieved by
 means of the instance's `value` or `textvalue` methods.
 
+#### Alternative approach
+
+By default the `Dropdown` runs a single callback regardless of the element
+chosen. This can be changed by specifying `elements` such that each element
+comprises a 3-list or 3-tuple with the following contents:
+ 0. String to display.
+ 1. Callback.
+ 2. Tuple of args (may be ()).
+
+In this case constructor args `callback` and `args` must not be supplied. Args
+received by the callback functions comprise the `Dropdown` instance followed by
+any supplied args.
+
 ###### [Contents](./README.md#0-contents)
 
 # 14. DialogBox class

gui/demos/menu.py

@@ -5,34 +5,40 @@
 
 import hardware_setup  # Create a display instance
 from gui.core.ugui import Screen, ssd
-import gui.fonts.freesans20 as freesans20
+import gui.fonts.freesans20 as font
 from gui.core.writer import CWriter
 
 from gui.widgets.menu import Menu
 from gui.widgets.buttons import CloseButton
 from gui.core.colors import *
-from gui.widgets.dialog import DialogBox
 
 class BaseScreen(Screen):
 
     def __init__(self):
         def cb(button, n):
-            print('Top level callback', n)
+            print('Help callback', n)
 
         def cb_sm(lb, n):
-            kwargs = {'writer' : wri, 'row': 60, 'col' : 2,
-                    'elements' : (('Yes', GREEN), ('No', RED), ('Foo', YELLOW)),
-                    'label' : 'Test dialog',
-                    }
             print('Submenu callback', lb.value(), lb.textvalue(), n)
-            if lb.value() == 0:
-                Screen.change(DialogBox, kwargs = kwargs)
 
         super().__init__()
-        mnu = (('Gas', cb_sm, (0,), ('Helium','Neon','Argon','Krypton','Xenon','Radon')),
+        mnu = (('Gas', (('Helium', cb_sm, (0,)),
-               ('Metal', cb_sm, (1,), ('Lithium', 'Sodium', 'Potassium','Rubidium','Caesium')),
+                        ('Neon', cb_sm, (1,)),
-               ('View', cb, (2,)))
+                        ('Argon', cb_sm, (2,)),
-        wri = CWriter(ssd, freesans20, GREEN, BLACK, verbose=False)
+                        ('Krypton', cb_sm, (3,)),
+                        ('Xenon', cb_sm, (4,)),
+                        ('Radon', cb_sm, (5,)))),
+               ('Metal',(('Lithium', cb_sm, (6,)),
+                         ('Sodium', cb_sm, (7,)),
+                         ('Potassium', cb_sm, (8,)),
+                         ('Rubidium', cb_sm, (9,)),
+                         ('More', (('Gold', cb_sm, (6,)),
+                                   ('Silver', cb_sm, (7,)),
+                                   ('Iron', cb_sm, (8,)),
+                                   ('Zinc', cb_sm, (9,)),
+                                   ('Copper', cb_sm, (10,)))))),
+               ('Help', cb, (2,)))
+        wri = CWriter(ssd, font, GREEN, BLACK, verbose=False)
         Menu(wri, bgcolor=BLUE, textcolor=WHITE, args = mnu)
         CloseButton(wri)
 

gui/widgets/dropdown.py

@@ -41,6 +41,15 @@ class Dropdown(Widget):
 
         self.entry_height = writer.height + 2 # Allow a pixel above and below text
         height = self.entry_height
+        e0 = elements[0]
+        # Check whether elements specified as (str, str,...) or ([str, callback, args], [...)
+        if isinstance(e0, tuple) or isinstance(e0, list):
+            te = [x[0] for x in elements]  # Copy text component
+            self.els = elements  # Retain original
+            elements = te
+            if callback is not dolittle:
+                raise ValueError('Cannot specify callback.')
+            callback = self._despatch
         if width is None:  # Allow for square at end for arrow
             self.textwidth = max(writer.stringlen(s) for s in elements)
             width = self.textwidth + 2 + height
@@ -88,3 +97,7 @@ class Dropdown(Widget):
         if len(self.elements) > 1:
             args = (self.writer, self.row - 2, self.col - 2, self)
             Screen.change(_ListDialog, args = args)
+
+    def _despatch(self, _):  # Run the callback specified in elements
+        x = self.els[self.value()]
+        x[1](self, *x[2])

gui/widgets/menu.py

@@ -16,35 +16,45 @@ from gui.core.colors import *
 # handled by Screen .move bound method
 class SubMenu(Window):
 
-    def __init__(self, menu, button, elements, cb, args):  # menu is parent Menu
+    def __init__(self, menu, button, elements):  # menu is parent Menu
+        self.menu = menu
+        self.button = button
         wri = menu.writer
         row = button.height + 2
         col = button.col  # Drop down below top level menu button
         # Need to determine Window dimensions from size of Listbox, which
         # depends on number and length of elements.
-        entry_height, lb_height, textwidth = Listbox.dimensions(wri, elements)
+        te = [x[0] for x in elements]  # Text part
+        self.elements = elements
+        entry_height, lb_height, textwidth = Listbox.dimensions(wri, te)
         lb_width = textwidth + 2
         # Calculate Window dimensions
         ap_height = lb_height + 6  # Allow for listbox border
         ap_width = lb_width + 6
         super().__init__(row, col, ap_height, ap_width)
-        self.listbox = Listbox(wri, row + 3, col + 3, elements = elements, width = lb_width,
+        Listbox(wri, row + 3, col + 3, elements = te, width = lb_width,
                 fgcolor = button.fgcolor, bgcolor = button.bgcolor, bdcolor=False, 
                 fontcolor = button.textcolor, select_color = menu.select_color,
                 callback = self.callback)
-        self.cb = cb
-        self.args = args
 
-    def callback(self, obj_listbox):
+    def callback(self, lbox):
         Screen.back()
-        self.cb(obj_listbox, *self.args) # CB can access obj_listbox.value() or .textvalue()
+        el = self.elements[lbox.value()]  # (text, cb, args)
+        if len(el) == 2:  # Recurse into submenu
+            args = (self.menu, self.button, el[1])
+            Screen.change(SubMenu, args = args)
+        else:
+            el[1](lbox, *el[2])
 
 # A Menu is a set of Button objects at the top of the screen. On press, Buttons either run the
 # user callback or instantiate a SubMenu
-# args: ((text, cb, (args,)),(text, cb, (args,), (elements,)), ...)
+# args is a list comprising items which may be a mixture of two types
+# Single items: (top_text, cb, (args, ...))
+# Submenus: (top_text, ((mnu_text, cb, (args, ...)),(mnu_text, cb, (args, ...)),...)
 class Menu:
 
-    def __init__(self, writer, *, height=25, bgcolor=None, fgcolor=None, textcolor=None, select_color=DARKBLUE, args):
+    def __init__(self, writer, *, height=25, bgcolor=None, fgcolor=None,
+                 textcolor=None, select_color=DARKBLUE, args):
         self.writer = writer
         self.select_color = select_color
         row = 2
@@ -54,8 +64,8 @@ class Menu:
                'height' : height,
                'textcolor' : textcolor, }
         for arg in args:
-            if len(arg) == 4:  # Handle submenu
+            if len(arg) == 2:  # Handle submenu
-                # txt, cb, (cbargs,), (elements,) = arg
+                # txt, ((element, cb, (cbargs,)),(element,cb, (cbargs,)), ..) = arg
                 b = Button(writer, row, col, text=arg[0],
                            callback=self.cb, args=arg, **btn)
             else:
@@ -64,6 +74,6 @@ class Menu:
                            callback=cb, args=cbargs, **btn)
             col = b.mcol
 
-    def cb(self, button, txt, user_cb, args, elements):  # Button pushed which calls submenu
+    def cb(self, button, txt, elements):  # Button pushed which calls submenu
-        args = (self, button, elements, user_cb, args)
+        args = (self, button, elements)
         Screen.change(SubMenu, args = args)

hardware_setup.py

@@ -51,4 +51,4 @@ sel = Pin(16, Pin.IN, Pin.PULL_UP)  # Operate current control
 prev = Pin(18, Pin.IN, Pin.PULL_UP)  # Move to previous control
 increase = Pin(20, Pin.IN, Pin.PULL_UP)  # Increase control's value
 decrease = Pin(17, Pin.IN, Pin.PULL_UP)  # Decrease control's value
-display = Display(ssd, nxt, sel, prev, increase, decrease)  #, 5)
+display = Display(ssd, nxt, sel, prev, increase, decrease, 5)