Add dialog.py demo.

gui/demos/dialog.py

@@ -0,0 +1,52 @@
+# dialog.py micro-gui demo of the DialogBox class
+
+# hardware_setup must be imported before other modules because of RAM use.
+import hardware_setup  # Create a display instance
+from gui.core.ugui import Screen, Window, ssd
+
+from gui.widgets.label import Label
+from gui.widgets.buttons import Button, CloseButton
+from gui.widgets.dialog import DialogBox
+from gui.core.writer import CWriter
+
+# Font for CWriter
+import gui.fonts.arial10 as arial10
+from gui.core.colors import *
+
+
+class BaseScreen(Screen):
+
+    def __init__(self):
+        super().__init__()
+        # Callback for Button
+        def fwd(button, my_kwargs):
+            Screen.change(DialogBox, kwargs = my_kwargs)
+
+        wri = CWriter(ssd, arial10, GREEN, BLACK, verbose=False)
+
+        row = 2
+        col = 2
+        # Trailing spaces ensure Label is wide enough to show results
+        self.lbl = Label(wri, row, col, 'Dialog box test   ')
+        # DialogBox constructor arguments. Here we pass all as keyword wargs.
+        kwargs = {'writer' : wri,
+                  'elements' : (('Yes', GREEN), ('No', RED), ('Foo', YELLOW)),
+                  'label' : 'Test dialog',
+                  }
+        row = 30
+        Button(wri, row, col, text = 'Dialog',
+               bgcolor = RED, textcolor = WHITE,
+               callback = fwd, args = (kwargs,))
+        CloseButton(wri)  # Quit the application
+
+    # Refresh the label after DialogBox has closed (but not when
+    # the screen first opens).
+    def after_open(self):
+        if (v := Window.value()) is not None:
+            self.lbl.value('Result: {}'.format(v))
+
+def test():
+    print('DialogBox demo.')
+    Screen.change(BaseScreen)
+
+test()