bubbletea/examples/pager/main.go

150 lines
3.7 KiB
Go
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package main
import (
"fmt"
"io/ioutil"
"os"
"strings"
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"github.com/charmbracelet/bubbles/viewport"
tea "github.com/charmbracelet/bubbletea"
"github.com/mattn/go-runewidth"
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)
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const (
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// You usually won't need this unless you're processing some pretty stuff
// with some pretty complicated ANSI escape sequences. Turn it on if you
// notice flickering.
//
// Also note that high performance rendering only works for programs that
// use the full size of the terminal. We're enabling that below with
// tea.AltScreen().
useHighPerformanceRenderer = false
headerHeight = 3
footerHeight = 3
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)
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func main() {
// Load some text to render
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content, err := ioutil.ReadFile("artichoke.md")
if err != nil {
fmt.Println("could not load file:", err)
os.Exit(1)
}
// Set PAGER_LOG to a path to log to a file. For example,
//
// export PAGER_LOG=debug.log
//
if os.Getenv("PAGER_LOG") != "" {
p := os.Getenv("PAGER_LOG")
f, err := tea.LogToFile(p, "pager")
if err != nil {
fmt.Printf("Could not open file %s: %v", p, err)
os.Exit(1)
}
defer f.Close()
}
// Use the full size of the terminal in its "Alternate Screen Buffer"
tea.AltScreen()
defer tea.ExitAltScreen()
if err := tea.NewProgram(
initialize(string(content)),
update,
view,
).Start(); err != nil {
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fmt.Println("could not run program:", err)
os.Exit(1)
}
}
type model struct {
content string
ready bool
viewport viewport.Model
}
func initialize(content string) func() (tea.Model, tea.Cmd) {
return func() (tea.Model, tea.Cmd) {
return model{
content: content, // keep content in the model
}, nil
}
}
func update(msg tea.Msg, mdl tea.Model) (tea.Model, tea.Cmd) {
m, _ := mdl.(model)
var (
cmd tea.Cmd
cmds []tea.Cmd
)
switch msg := msg.(type) {
case tea.KeyMsg:
if msg.Type == tea.KeyCtrlC {
return m, tea.Quit
}
case tea.WindowSizeMsg:
verticalMargins := headerHeight + footerHeight
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if !m.ready {
m.viewport = viewport.NewModel(msg.Width, msg.Height-verticalMargins)
m.viewport.YPosition = headerHeight
m.viewport.HighPerformanceRendering = useHighPerformanceRenderer
m.viewport.SetContent(m.content)
m.ready = true
} else {
m.viewport.Width = msg.Width
m.viewport.Height = msg.Height - verticalMargins
}
// Render (or re-render) the whole viewport
if useHighPerformanceRenderer {
cmds = append(cmds, viewport.Sync(m.viewport))
}
}
// Because we're using the viewport's default update function (with pager-
// style navigation) it's important that the viewport's update function:
//
// * Recieves messages from the Bubble Tea runtime
// * Returns commands to the Bubble Tea runtime
m.viewport, cmd = viewport.Update(msg, m.viewport)
if useHighPerformanceRenderer {
cmds = append(cmds, cmd)
}
return m, tea.Batch(cmds...)
}
func view(mdl tea.Model) string {
m, _ := mdl.(model)
if !m.ready {
return "\n Initalizing..."
}
headerTop := "╭───────────╮"
headerMid := "│ Mr. Pager ├"
headerBot := "╰───────────╯"
headerMid += strings.Repeat("─", m.viewport.Width-runewidth.StringWidth(headerMid))
header := fmt.Sprintf("%s\n%s\n%s", headerTop, headerMid, headerBot)
footerTop := "╭──────╮"
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footerMid := fmt.Sprintf("┤ %3.f%% │", m.viewport.ScrollPercent()*100)
footerBot := "╰──────╯"
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gapSize := m.viewport.Width - runewidth.StringWidth(footerMid)
footerTop = strings.Repeat(" ", gapSize) + footerTop
footerMid = strings.Repeat("─", gapSize) + footerMid
footerBot = strings.Repeat(" ", gapSize) + footerBot
footer := footerTop + "\n" + footerMid + "\n" + footerBot
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return fmt.Sprintf("%s\n%s\n%s", header, viewport.View(m.viewport), footer)
}