calculator example

examples/calculator.py

@@ -1,17 +1,27 @@
+from decimal import Decimal
+
 from rich.align import Align
-from rich.console import Console, ConsoleOptions, RenderResult
+from rich.console import Console, ConsoleOptions, RenderResult, RenderableType
+from rich.padding import Padding
 from rich.text import Text
 
+
 from textual.app import App
 from textual import events
+from textual.message import Message
+from textual.reactive import Reactive
 from textual.view import View
-from textual.widgets import Button, Static
+from textual.widget import Widget
+from textual.widgets import Button
 from textual.layouts.grid import GridLayout
 
 try:
     from pyfiglet import Figlet
 except ImportError:
     print("Please install pyfiglet to run this example")
+    import sys
+
+    sys.exit()
 
 
 class FigletText:
@@ -24,10 +34,8 @@ class FigletText:
         self, console: Console, options: ConsoleOptions
     ) -> RenderResult:
         size = min(options.max_width / 2, options.max_height)
-
-        text = self.text
         if size < 4:
-            yield Text(text, style="bold")
+            yield Text(self.text, style="bold")
         else:
             if size < 7:
                 font_name = "mini"
@@ -37,42 +45,148 @@ class FigletText:
                 font_name = "standard"
             else:
                 font_name = "big"
-            font = Figlet(font=font_name)
-            yield Text(font.renderText(text).rstrip("\n"), style="bold")
+            font = Figlet(font=font_name, width=options.max_width)
+            yield Text(font.renderText(self.text).rstrip("\n"), style="bold")
+
+
+class Numbers(Widget):
+    """The digital display of the calculator."""
+
+    value: Reactive[str] = Reactive("0")
+
+    def render(self) -> RenderableType:
+        return Padding(
+            Align.right(FigletText(self.value), vertical="middle"),
+            (0, 1),
+            style="white on rgb(51,51,51)",
+        )
 
 
 class CalculatorApp(App):
-    async def on_startup(self, event: events.Startup) -> None:
+    """A working calculator app."""
 
+    async def on_load(self, event: events.Load) -> None:
+        """Sent when the app starts, but before displaying anything."""
+
+        self.left = Decimal("0")
+        self.right = Decimal("0")
+        self.value = ""
+        self.operator = "+"
+        self.numbers = Numbers()
+
+        def make_button(text: str, style: str) -> Button:
+            """Create a button with the given Figlet label."""
+            return Button(FigletText(text), style=style, name=text)
+
+        dark = "white on rgb(51,51,51)"
+        light = "black on rgb(165,165,165)"
+        yellow = "white on rgb(255,159,7)"
+
+        button_styles = {
+            "AC": light,
+            "C": light,
+            "+/-": light,
+            "%": light,
+            "/": yellow,
+            "X": yellow,
+            "-": yellow,
+            "+": yellow,
+            "=": yellow,
+        }
+
+        # Make all the buttons
+        self.buttons = {
+            name: make_button(name, button_styles.get(name, dark))
+            for name in "+/-,%,/,7,8,9,X,4,5,6,-,1,2,3,+,.,=".split(",")
+        }
+
+        self.zero = make_button("0", dark)
+        self.ac = make_button("AC", light)
+        self.c = make_button("C", light)
+        self.c.visible = False
+
+    async def on_startup(self, event: events.Startup) -> None:
+        """Sent when the app has gone full screen."""
+
+        # Create the layout which defines where our widgets will go
         layout = GridLayout(gap=(2, 1), gutter=1, align=("center", "center"))
         await self.push_view(View(layout=layout))
 
+        # Create rows / columns / areas
         layout.add_column("col", max_size=30, repeat=4)
-        layout.add_row("numbers")
+        layout.add_row("numbers", max_size=15)
         layout.add_row("row", max_size=15, repeat=5)
         layout.add_areas(
-            numbers="col1-start|col4-end,numbers", zero="col1-start|col2-end,row5"
+            clear="col1,row1",
+            numbers="col1-start|col4-end,numbers",
+            zero="col1-start|col2-end,row5",
         )
-
-        def make_button(text: str) -> Button:
-            return Button(FigletText(text), style="white on rgb(51,51,51)")
-
-        buttons = {
-            name: make_button(name)
-            for name in "AC,+/-,%,/,7,8,9,X,4,5,6,-,1,2,3,+,.,=".split(",")
-        }
-        for name in ("AC", "+/-", "%"):
-            buttons[name].style = "black on rgb(165,165,165)"
-        for name in "/X-+=":
-            buttons[name].style = "white on rgb(255,159,7)"
-
-        numbers = Align.right(FigletText("0"), vertical="middle")
-
+        # Place out widgets in to the layout
+        layout.place(clear=self.c)
         layout.place(
-            *buttons.values(),
-            numbers=Static(numbers, padding=(0, 1), style="white on rgb(51,51,51)"),
-            zero=make_button("0"),
+            *self.buttons.values(), clear=self.ac, numbers=self.numbers, zero=self.zero
         )
 
+    async def message_button_pressed(self, message: Message) -> None:
+        """A message sent by the button widget"""
+
+        assert isinstance(message.sender, Button)
+        button_name = message.sender.name
+
+        def do_math() -> bool:
+            operator = self.operator
+            right = self.right
+            if operator == "+":
+                self.left += right
+            elif operator == "-":
+                self.left -= right
+            elif operator == "/":
+                try:
+                    self.left /= right
+                except ZeroDivisionError:
+                    self.numbers.value = "Error"
+                    return False
+            elif operator == "X":
+                self.left *= right
+            return True
+
+        if button_name.isdigit():
+            self.value = self.value.lstrip("0") + button_name
+            self.numbers.value = self.value
+        elif button_name == "+/-":
+            self.value = str(Decimal(self.value or "0") * -1)
+            self.numbers.value = self.value
+        elif button_name == "%":
+            self.value = str(Decimal(self.value or "0") / Decimal(100))
+            self.numbers.value = self.value
+        elif button_name == ".":
+            if "." not in self.value:
+                self.value += "."
+                self.numbers.value = self.value
+        elif button_name == "AC":
+            self.value = ""
+            self.left = self.right = Decimal(0)
+            self.operator = "+"
+            self.numbers.value = "0"
+        elif button_name == "C":
+            self.value = ""
+            self.numbers.value = "0"
+        elif button_name in ("+", "-", "/", "X"):
+            self.right = Decimal(self.value or "0")
+            if do_math():
+                self.numbers.value = str(self.left)
+            self.value = ""
+            self.operator = button_name
+        elif button_name == "=":
+            if self.value:
+                self.right = Decimal(self.value or "0")
+            if do_math():
+                self.numbers.value = str(self.left)
+            self.value = ""
+
+        show_ac = self.value in ("", "0") and self.numbers.value == "0"
+        self.c.visible = not show_ac
+        self.ac.visible = show_ac
+
 
 CalculatorApp.run(title="Calculator Test")