Add window resize example

examples/resize/main.go

@@ -0,0 +1,75 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+
+	tea "github.com/charmbracelet/bubbletea"
+	"github.com/charmbracelet/lipgloss"
+)
+
+var (
+	windowStyle = lipgloss.NewStyle().
+			Border(lipgloss.RoundedBorder()).
+			BorderForeground(lipgloss.AdaptiveColor{Light: "#874BFD", Dark: "#7D56F4"}).
+			Align(lipgloss.Center)
+
+	keywordStyle = lipgloss.NewStyle().
+			Foreground(lipgloss.Color("#F25D94"))
+)
+
+type model struct {
+	width, height int
+}
+
+func (m model) Init() tea.Cmd {
+	return nil
+}
+
+func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
+	switch msg := msg.(type) {
+	case tea.WindowSizeMsg:
+		// The window dimensions are sent to update when the program first
+		// starts as well as after a resize.
+		m.width, m.height = msg.Width, msg.Height
+		return m, nil
+
+	case tea.KeyMsg:
+		switch msg.String() {
+		case "ctrl+c", "q":
+			return m, tea.Quit
+		default:
+			return m, nil
+		}
+	default:
+		return m, nil
+	}
+}
+
+func (m model) View() string {
+	if m.width == 0 || m.height == 0 {
+		return "Waiting for dimensions..."
+	}
+
+	s := fmt.Sprintf(
+		"Window is %s x %s cells.\n\nResize to update. Press q to exit.",
+		keywordStyle.Render(strconv.Itoa(m.width)),
+		keywordStyle.Render(strconv.Itoa(m.height)),
+	)
+	s = strings.Repeat("\n", m.height/2-lipgloss.Height(s)) + s
+
+	return windowStyle.Copy().
+		Width(m.width - windowStyle.GetHorizontalBorderSize()).
+		Height(m.height - windowStyle.GetVerticalBorderSize()).
+		Render(s)
+}
+
+func main() {
+	p := tea.NewProgram(model{}, tea.WithAltScreen())
+	if err := p.Start(); err != nil {
+		fmt.Println("Error running program:", err)
+		os.Exit(1)
+	}
+}