Publish Comprehensive Rust 🦀

src/exercises/day-3/simple-gui.rs

@@ -0,0 +1,160 @@
+// Copyright 2022 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// ANCHOR: setup
+pub trait Widget {
+    /// Natural width of `self`.
+    fn width(&self) -> usize;
+
+    /// Draw the widget into a buffer.
+    fn draw_into(&self, buffer: &mut dyn std::fmt::Write);
+
+    /// Draw the widget on standard output.
+    fn draw(&self) {
+        let mut buffer = String::new();
+        self.draw_into(&mut buffer);
+        println!("{}", &buffer);
+    }
+}
+
+pub struct Label {
+    label: String,
+}
+
+impl Label {
+    fn new(label: &str) -> Label {
+        Label {
+            label: label.to_owned(),
+        }
+    }
+}
+
+pub struct Button {
+    label: Label,
+    callback: Box<dyn FnMut()>,
+}
+
+impl Button {
+    fn new(label: &str, callback: Box<dyn FnMut()>) -> Button {
+        Button {
+            label: Label::new(label),
+            callback,
+        }
+    }
+}
+
+pub struct Window {
+    title: String,
+    widgets: Vec<Box<dyn Widget>>,
+}
+
+impl Window {
+    fn new(title: &str) -> Window {
+        Window {
+            title: title.to_owned(),
+            widgets: Vec::new(),
+        }
+    }
+
+    fn add_widget(&mut self, widget: Box<dyn Widget>) {
+        self.widgets.push(widget);
+    }
+}
+
+// ANCHOR_END: setup
+
+// ANCHOR: Window-width
+impl Widget for Window {
+    fn width(&self) -> usize {
+        // ANCHOR_END: Window-width
+        std::cmp::max(
+            self.title.chars().count(),
+            self.widgets.iter().map(|w| w.width()).max().unwrap_or(0),
+        )
+    }
+
+    // ANCHOR: Window-draw_into
+    fn draw_into(&self, buffer: &mut dyn std::fmt::Write) {
+        // ANCHOR_END: Window-draw_into
+        let mut inner = String::new();
+        for widget in &self.widgets {
+            widget.draw_into(&mut inner);
+        }
+
+        let window_width = self.width();
+
+        // TODO: after learning about error handling, you can change
+        // draw_into to return Result<(), std::fmt::Error>. Then use
+        // the ?-operator here instead of .unwrap().
+        writeln!(buffer, "+-{:-<window_width$}-+", "").unwrap();
+        writeln!(buffer, "| {:^window_width$} |", &self.title).unwrap();
+        writeln!(buffer, "+={:=<window_width$}=+", "").unwrap();
+        for line in inner.lines() {
+            writeln!(buffer, "| {:window_width$} |", line).unwrap();
+        }
+        writeln!(buffer, "+-{:-<window_width$}-+", "").unwrap();
+    }
+}
+
+// ANCHOR: Button-width
+impl Widget for Button {
+    fn width(&self) -> usize {
+        // ANCHOR_END: Button-width
+        self.label.width() + 8 // add a bit of padding
+    }
+
+    // ANCHOR: Button-draw_into
+    fn draw_into(&self, buffer: &mut dyn std::fmt::Write) {
+        // ANCHOR_END: Button-draw_into
+        let width = self.width();
+        let mut label = String::new();
+        self.label.draw_into(&mut label);
+
+        writeln!(buffer, "+{:-<width$}+", "").unwrap();
+        for line in label.lines() {
+            writeln!(buffer, "|{:^width$}|", &line).unwrap();
+        }
+        writeln!(buffer, "+{:-<width$}+", "").unwrap();
+    }
+}
+
+// ANCHOR: Label-width
+impl Widget for Label {
+    fn width(&self) -> usize {
+        // ANCHOR_END: Label-width
+        self.label
+            .lines()
+            .map(|line| line.chars().count())
+            .max()
+            .unwrap_or(0)
+    }
+
+    // ANCHOR: Label-draw_into
+    fn draw_into(&self, buffer: &mut dyn std::fmt::Write) {
+        // ANCHOR_END: Label-draw_into
+        writeln!(buffer, "{}", &self.label).unwrap();
+    }
+}
+
+// ANCHOR: main
+fn main() {
+    let mut window = Window::new("Rust GUI Demo 1.23");
+    window.add_widget(Box::new(Label::new("This is a small text GUI demo.")));
+    window.add_widget(Box::new(Button::new(
+        "Click me!",
+        Box::new(|| println!("You clicked the button!")),
+    )));
+    window.draw();
+}
+// ANCHOR_END: main