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|
# go-tui — Complete Reference for LLMs
> Declarative terminal UI framework for Go with templ-like syntax and flexbox layout.
> Pure Go, minimal dependencies, generates type-safe code from `.gsx` templates.
## Installation
```bash
go get github.com/grindlemire/go-tui
go install github.com/grindlemire/go-tui/cmd/tui@latest
```
## CLI Commands
```bash
tui generate [path...] # Generate Go code from .gsx files
tui check [path...] # Validate .gsx files without writing output
tui fmt [path...] # Format .gsx files
tui fmt --check [path...] # Check formatting without modifying
tui lsp # Start language server (stdio)
```
## Architecture
```
.gsx files → tui generate → _gsx.go files → go build → binary
```
At runtime: Event Loop → Layout Engine (flexbox) → Double-buffered Render → ANSI Terminal Output
## GSX Syntax
`.gsx` files are Go files with a `templ` keyword for declaring UI components. They compile to standard Go code.
### Pure Components (stateless)
```gsx
package main
import tui "github.com/grindlemire/go-tui"
templ Greeting(name string) {
<span class="text-cyan font-bold">{"Hello, " + name}</span>
}
// With children slot
templ Card(title string) {
<div class="border-rounded p-1 flex-col gap-1">
<span class="font-bold">{title}</span>
{children...}
</div>
}
// Usage
templ App() {
@Card("Info") {
@Greeting("Alice")
}
}
```
### Struct Components (stateful)
```gsx
type counter struct {
count *tui.State[int]
}
func Counter() *counter {
return &counter{count: tui.NewState(0)}
}
func (c *counter) KeyMap() tui.KeyMap {
return tui.KeyMap{
tui.On(tui.KeyEscape, func(ke tui.KeyEvent) { ke.App().Stop() }),
tui.On(tui.Rune('+'), func(ke tui.KeyEvent) {
c.count.Update(func(v int) int { return v + 1 })
}),
}
}
templ (c *counter) Render() {
<div class="flex-col items-center justify-center h-full">
<span class="text-cyan font-bold">{fmt.Sprintf("Count: %d", c.count.Get())}</span>
</div>
}
```
### Struct Components with Children
```gsx
type panel struct {
title string
children []*tui.Element
}
func NewPanel(title string, children []*tui.Element) *panel {
return &panel{title: title, children: children}
}
templ (p *panel) Render() {
<div class="border-rounded p-1 flex-col">
<span class="font-bold">{p.title}</span>
{children...}
</div>
}
```
### Control Flow
```gsx
// Conditionals
if condition {
<span>True</span>
} else if otherCondition {
<span>Other</span>
} else {
<span>Default</span>
}
// Loops
for i, item := range items {
<span>{fmt.Sprintf("%d: %s", i, item)}</span>
}
// Local element binding
badge := <span class="font-bold">{label}</span>
<div>{badge}</div>
```
### Go Expressions
```gsx
<span>{fmt.Sprintf("Count: %d", c.count.Get())}</span>
<span class={computedClass(isActive)}>Dynamic class</span>
<div width={42} height={10} flexGrow={1.5}>content</div>
```
## main.go Pattern
```go
package main
import (
"fmt"
"os"
tui "github.com/grindlemire/go-tui"
)
func main() {
app, err := tui.NewApp(
tui.WithRootComponent(MyComponent()),
// Optional:
// tui.WithMouse(),
// tui.WithFrameRate(60),
// tui.WithInlineHeight(10),
// tui.WithGlobalKeyHandler(func(ke tui.KeyEvent) bool { return false }),
)
if err != nil {
fmt.Fprintf(os.Stderr, "Error: %v\n", err)
os.Exit(1)
}
defer app.Close()
if err := app.Run(); err != nil {
fmt.Fprintf(os.Stderr, "Error: %v\n", err)
os.Exit(1)
}
}
```
## Single-Frame Printing
For CLI tools that render styled output once and exit, without starting an interactive app:
```go
// Print to stdout (auto-detects terminal width, falls back to 80)
tui.Print(MyComponent("hello"))
// Return as ANSI string (no trailing newline)
s := tui.Sprint(view, tui.WithPrintWidth(80))
// Write to any io.Writer (appends trailing newline)
tui.Fprint(w, view, tui.WithPrintWidth(120))
```
All three accept a `Viewable` (generated `.gsx` views and raw `*Element` values). Same components work with both `Print` and `App.Run()`.
```go
// PrintOption
tui.WithPrintWidth(w int) // Explicit width; default: auto-detect, fallback 80
```
## Built-in Elements
### Container Elements
| Element | Description | Default Direction |
|---------|-------------|-------------------|
| `<div>` | Block flex container (primary layout element) | Row |
| `<span>` | Inline text container | — |
| `<p>` | Paragraph with automatic text wrapping | — |
| `<ul>` | Unordered list container | Column |
| `<li>` | List item (auto bullet prefix) | — |
| `<button>` | Clickable element | — |
| `<modal>` | Full-screen overlay dialog with backdrop | — |
| `<table>` | Table container | Column |
### Self-Closing (Void) Elements
| Element | Description |
|---------|-------------|
| `<input />` | Single-line text input. Attrs: `value` (`*State[string]`), `placeholder`, `width`, `border`, `focusColor`, `borderGradient`, `focusGradient`, `onSubmit`, `onChange` |
| `<textarea />` | Multi-line text input. Attrs: `value` (`*State[string]`), `placeholder`, `width`, `maxHeight`, `border`, `focusColor`, `borderGradient`, `focusGradient`, `submitKey`, `onSubmit` |
| `<progress />` | Progress bar. Attrs: `value`, `max` |
| `<hr />` | Horizontal rule |
| `<br />` | Line break |
## Attributes
### Layout
| Attribute | Type | Description |
|-----------|------|-------------|
| `width` | `int` | Fixed width in characters |
| `widthPercent` | `int` | Width as percentage |
| `height` | `int` | Fixed height in rows |
| `heightPercent` | `int` | Height as percentage |
| `minWidth` / `maxWidth` | `int` | Min/max width constraints |
| `minHeight` / `maxHeight` | `int` | Min/max height constraints |
| `direction` | `tui.Direction` | `tui.Row` or `tui.Column` |
| `justify` | `tui.Justify` | Main axis alignment |
| `align` | `tui.Align` | Cross axis alignment |
| `alignSelf` | `tui.Align` | Override parent's align |
| `gap` | `int` | Gap between children |
| `flexGrow` | `float64` | Flex grow factor |
| `flexShrink` | `float64` | Flex shrink factor |
| `padding` | `int` | Padding on all sides |
| `margin` | `int` | Margin on all sides |
### Visual
| Attribute | Type | Description |
|-----------|------|-------------|
| `border` | `tui.BorderStyle` | Border style |
| `background` | `tui.Color` | Background color |
| `text` | `string` | Text content |
| `textStyle` | `tui.Style` | Text styling |
| `textAlign` | `string` | `"left"`, `"center"`, `"right"` |
| `borderStyle` | `tui.Style` | Border line styling |
| `borderTitle` | `string` | Title text centered in the top border |
### Identity & Behavior
| Attribute | Type | Description |
|-----------|------|-------------|
| `id` | `string` | Unique identifier |
| `class` | `string` | Tailwind-style classes |
| `disabled` | `bool` | Disable interaction |
| `ref` | `*tui.Ref` | Bind to a reference |
| `deps` | expression | Explicit state dependencies |
| `focusable` | `bool` | Enable focus |
| `onFocus` / `onBlur` | `func(*tui.Element)` | Focus callbacks |
| `onActivate` | `func()` | Enter activation callback |
### Scroll
| Attribute | Type | Description |
|-----------|------|-------------|
| `scrollable` | `tui.ScrollMode` | `ScrollVertical`, `ScrollHorizontal`, `ScrollBoth` |
| `scrollOffset` | `int, int` | x, y scroll position |
| `scrollbarStyle` | `tui.Style` | Track style |
| `scrollbarThumbStyle` | `tui.Style` | Thumb style |
| `hideScrollbar` | `bool` | Hide scrollbar and reclaim gutter width |
### Modal
| Attribute | Type | Description |
|-----------|------|-------------|
| `open` | `*State[bool]` | Controls modal visibility (required) |
| `backdrop` | `string` | `"dim"` (default), `"blank"`, or `"none"` |
| `closeOnEscape` | `bool` | Escape closes modal (default `true`) |
| `closeOnBackdropClick` | `bool` | Backdrop click closes modal (default `true`) |
| `trapFocus` | `bool` | Restrict Tab to modal children and block unhandled keys from parents (default `true`) |
| `keyMap` | `expression` | Custom `KeyMap` bindings for the modal |
### Activation
| Attribute | Type | Description |
|-----------|------|-------------|
| `onActivate` | `func()` | Called when Enter is pressed while focused |
## Tailwind Classes (Complete Reference)
### Layout Direction
`flex` `flex-row` `flex-col`
### Flex Sizing
`grow` `grow-0` `shrink` `shrink-0` `flex-1` `flex-auto` `flex-initial` `flex-none` `flex-grow-N` `flex-shrink-N`
### Width & Height
`w-N` `h-N` `w-full` `h-full` `w-auto` `h-auto` `w-1/2` `w-1/3` `w-2/3` `h-1/2` `h-1/3` `h-2/3` `min-w-N` `max-w-N` `min-h-N` `max-h-N`
### Justify Content
`justify-start` `justify-center` `justify-end` `justify-between` `justify-around` `justify-evenly`
### Align Items / Self
`items-start` `items-center` `items-end` `items-stretch` `self-start` `self-center` `self-end` `self-stretch`
### Flex Wrap
`flex-wrap` `flex-wrap-reverse` `flex-nowrap`
### Align Content (for wrapped containers)
`content-start` `content-end` `content-center` `content-stretch` `content-between` `content-around`
### Spacing
`gap-N` `p-N` `px-N` `py-N` `pt-N` `pr-N` `pb-N` `pl-N` `m-N` `mx-N` `my-N` `mt-N` `mr-N` `mb-N` `ml-N`
### Borders
`border` `border-single` `border-double` `border-rounded` `border-thick` `border-COLOR` `border-[#hex]` `border-gradient-C1-C2[-dir]`
### Text Styling
`font-bold` `font-dim` `text-dim` `italic` `underline` `strikethrough` `blink` `reverse` `text-left` `text-center` `text-right` `truncate` `wrap` `nowrap`
### Colors
Named: `text-COLOR` `text-bright-COLOR` `bg-COLOR` `bg-bright-COLOR`
Hex: `text-[#hex]` `bg-[#hex]`
Colors: `red` `green` `blue` `cyan` `magenta` `yellow` `white` `black` (plus `bright-` variants)
### Gradients
`text-gradient-C1-C2[-dir]` `bg-gradient-C1-C2[-dir]` `border-gradient-C1-C2[-dir]`
Directions: `-h` (horizontal, default), `-v` (vertical), `-dd` (diagonal down), `-du` (diagonal up)
### Scroll & Overflow
`overflow-scroll` `overflow-y-scroll` `overflow-x-scroll` `overflow-hidden` `scrollbar-hidden` `scrollbar-COLOR` `scrollbar-thumb-COLOR` `scrollbar-[#hex]` `scrollbar-thumb-[#hex]`
### Other
`focusable` `hidden`
## Key Types
```go
// Dimensions
tui.Fixed(10) // 10 characters
tui.Percent(50) // 50% of parent
tui.Auto() // Size to content
// Borders
tui.BorderNone / tui.BorderSingle / tui.BorderDouble / tui.BorderRounded / tui.BorderThick
// Direction
tui.Row / tui.Column
// Justify
tui.JustifyStart / tui.JustifyCenter / tui.JustifyEnd
tui.JustifySpaceBetween / tui.JustifySpaceAround / tui.JustifySpaceEvenly
// Align
tui.AlignStart / tui.AlignCenter / tui.AlignEnd / tui.AlignStretch
// TextAlign
tui.TextAlignLeft / tui.TextAlignCenter / tui.TextAlignRight
// ScrollMode
tui.ScrollNone / tui.ScrollVertical / tui.ScrollHorizontal / tui.ScrollBoth
// OverflowMode
tui.OverflowVisible / tui.OverflowHidden
// Colors
tui.Black / tui.Red / tui.Green / tui.Yellow / tui.Blue / tui.Magenta / tui.Cyan / tui.White
tui.BrightBlack / tui.BrightRed / tui.BrightGreen / ... / tui.BrightWhite
tui.ANSIColor(index) // 256 palette
tui.RGBColor(r, g, b) // 24-bit true color
tui.HexColor("#ff6600") // Hex string
tui.DefaultColor() // Terminal default
// Gradients
tui.NewGradient(tui.Red, tui.Blue) // Horizontal
tui.NewGradient(tui.Red, tui.Blue).WithDirection(tui.GradientVertical) // Vertical
// Directions: GradientHorizontal, GradientVertical, GradientDiagonalDown, GradientDiagonalUp
// Style (chainable)
tui.NewStyle().Bold().Dim().Italic().Underline().Strikethrough().Reverse().Blink()
.Foreground(tui.Cyan).Background(tui.Black)
// State (generic reactive container)
count := tui.NewState(0)
count.Get() // Read (safe from any goroutine)
count.Set(5) // Write (main loop only)
count.Update(func(v int) int { ... }) // Read-modify-write (main loop only)
unbind := count.Bind(func(v int) { }) // Called on change
// Refs (element references for hit testing)
ref := tui.NewRef() // Single element
list := tui.NewRefList() // Loop elements: list.At(i) to bind, list.El(i) to read
m := tui.NewRefMap[string]() // Keyed elements: m.At(key) to bind, m.El(key) to read
// Events (cross-component pub/sub)
bus := tui.NewEvents[MyEvent]("topic")
bus.Emit(MyEvent{...})
unsub := bus.Subscribe(func(e MyEvent) { ... })
```
## Component Interfaces
All optional except `Component.Render`:
```go
// Required
type Component interface {
Render(app *App) *Element
}
// Keyboard input
type KeyListener interface {
KeyMap() KeyMap
}
// Mouse input
type MouseListener interface {
HandleMouse(MouseEvent) bool
}
// Background timers/channels
type WatcherProvider interface {
Watchers() []Watcher
}
// Setup/cleanup on mount/unmount
type Initializer interface {
Init() func() // returned func is cleanup
}
// Receive updated props on re-render
type PropsUpdater interface {
UpdateProps(fresh Component)
}
// Auto-generated: binds State/Events fields to app
type AppBinder interface {
BindApp(app *App)
}
```
## Key Bindings
```go
func (c *myComp) KeyMap() tui.KeyMap {
return tui.KeyMap{
tui.On(tui.KeyEscape, handler), // Special key, propagates
tui.OnStop(tui.KeyEnter, handler), // Special key, stops propagation
tui.On(tui.Rune('q'), handler), // Specific character
tui.OnStop(tui.Rune('/'), handler), // Specific char, stops propagation
tui.On(tui.AnyRune, handler), // Any printable character
tui.OnStop(tui.AnyRune, handler), // Any printable, stops propagation
// Preemptive binding (fires before normal handlers; used by modal)
tui.OnPreemptStop(tui.AnyKey, func(ke tui.KeyEvent) {}), // catch-all blocker
}
}
```
**KeyEvent fields:** `ke.Key`, `ke.Rune`, `ke.Mod` (ModCtrl, ModAlt, ModShift), `ke.App()`
**Special keys:** `KeyUp` `KeyDown` `KeyLeft` `KeyRight` `KeyEnter` `KeyTab` `KeyEscape` `KeyBackspace` `KeyDelete` `KeyHome` `KeyEnd` `KeyPageUp` `KeyPageDown` `KeyInsert` `KeyCtrlA`–`KeyCtrlZ` `KeyF1`–`KeyF12`
## Mouse Handling
Requires `tui.WithMouse()` in app options.
```go
func (c *myComp) HandleMouse(me tui.MouseEvent) bool {
return tui.HandleClicks(me,
tui.Click(c.saveBtn, c.onSave), // Single ref
tui.Click(c.itemRefs, c.onItemClick), // RefList
)
}
```
**MouseEvent fields:** `me.Button` (MouseLeft, MouseRight, MouseWheelUp, MouseWheelDown), `me.Action` (MousePress, MouseRelease, MouseDrag), `me.X`, `me.Y`, `me.App()`
## Watchers
```go
func (c *myComp) Watchers() []tui.Watcher {
return []tui.Watcher{
tui.OnTimer(time.Second, c.tick), // Timer
tui.Watch(c.dataCh, c.onData), // Channel watcher
}
}
```
Callbacks run on the main event loop, so you can mutate state directly.
## Scroll API
```go
el.ScrollTo(x, y) // Absolute position (clamped)
el.ScrollBy(dx, dy) // Relative adjustment (clamped)
el.ScrollToTop()
el.ScrollToBottom() // With deferred re-scroll after layout
el.ScrollIntoView(child) // Minimal scroll to make child visible
el.ScrollOffset() (x, y) // Current position
el.MaxScroll() (maxX, maxY)
el.ContentSize() (w, h)
el.ViewportSize() (w, h)
el.IsAtBottom() bool
```
## Focus Management
```go
// Element-level
element.Focus() / element.Blur() / element.IsFocused()
// App-level cycling
app.FocusNext() / app.FocusPrev() / app.Focused()
// FocusGroup for section-level switching
sidebar := tui.NewState(true)
content := tui.NewState(false)
fg := tui.MustNewFocusGroup(sidebar, content)
fg.Next() / fg.Prev() / fg.Current()
// fg.KeyMap() returns Tab/Shift+Tab bindings
// Modal focus trapping (automatic when trapFocus is enabled)
// Tab/Shift+Tab cycle within modal children only
// Enter triggers focused element's onActivate callback
// All parent key handlers are blocked via preemptive dispatch
```
## State Batching
```go
ke.App().Batch(func() {
state1.Set(val1)
state2.Set(val2)
// Single re-render after batch completes
})
```
## Thread Safety
| Operation | Main Loop | Any Goroutine |
|-----------|-----------|---------------|
| `state.Get()` | Yes | Yes |
| `state.Set()` / `state.Update()` | Yes | Use `app.QueueUpdate()` |
| `events.Emit()` | Yes | Use `app.QueueUpdate()` |
| `app.QueueUpdate(func() { ... })` | Yes | Yes |
## App Options
```go
tui.WithRootComponent(comp) // Required: root component
tui.WithMouse() // Enable mouse support
tui.WithFrameRate(fps int) // Default: 60
tui.WithInlineHeight(rows int) // Inline mode (not fullscreen)
tui.WithGlobalKeyHandler(func(KeyEvent) bool) // Global key intercept
tui.WithInputLatency(d time.Duration) // Coalesce rapid input
tui.WithEventQueueSize(n int) // Event queue buffer size
```
## App Methods
```go
// Standard lifecycle
app.Run() error // Start event loop (blocks), calls Open() + Close() internally
app.Stop() // Stop the event loop
app.Close() error // Restore terminal (idempotent)
app.StopCh() <-chan struct{} // Closed when app stops
// Manual event loop
app.Open() error // Initialize without blocking (signals, input reader, initial render)
app.Events() <-chan Event // Read-only channel for select multiplexing (input prioritized)
app.Dispatch(Event) bool // Route a single event through key/mouse/resize dispatch
app.DispatchEvents() bool // Drain all pending events (non-blocking), false if stopped
app.Step() bool // DispatchEvents + Render in one call, false if stopped
app.Render() // Re-render if dirty (no-op when clean)
app.RenderFull() // Force full redraw
// State and updates
app.Batch(func()) // Batch state updates
app.QueueUpdate(func()) // Schedule work on main loop (drops if full)
app.MarkDirty() // Mark app as needing render
// Focus
app.FocusNext() / app.FocusPrev() / app.Focused()
// Inline mode
app.PrintAbove(string) // Print above inline widget
app.StreamAbove() *StreamWriter // Stream text char-by-char above inline widget
```
### Manual Event Loop Patterns
Three ways to drive the event loop:
```go
// 1. Run() - standard, go-tui owns the loop
app.Run()
// 2. Step() - you own frame timing
app.Open()
defer app.Close()
for {
<-ticker.C
drainMyChannels() // mutate state directly, no QueueUpdate needed
if !app.Step() { return }
}
// 3. Events() + select - multiplex with external channels
app.Open()
defer app.Close()
for {
select {
case ev := <-app.Events():
app.Dispatch(ev)
case msg := <-myChannel:
handleMsg(msg) // mutate state directly
case <-app.StopCh():
return
}
app.Render()
}
```
## Inline Mode
For CLI tools that render a widget inline (not fullscreen):
```go
app, _ := tui.NewApp(
tui.WithRootComponent(myComp),
tui.WithInlineHeight(5), // Reserve 5 terminal rows
)
```
Inline mode limitations: modals (`<modal>`) are not supported because the buffer covers only a partial terminal region. Use `app.EnterAlternateScreen()` to switch to full-screen before opening a modal, then `app.ExitAlternateScreen()` when it closes.
### StreamAbove
`app.StreamAbove()` returns a `*StreamWriter` for character-by-character streaming above the inline widget. The writer implements `io.WriteCloser` and adds `WriteStyled` and `WriteGradient` methods. Goroutine-safe. Close it when done to finalize the partial line.
```go
go func() {
w := app.StreamAbove()
// Plain write (backward compatible)
fmt.Fprint(w, "hello ")
// Styled write
w.WriteStyled("bold text", tui.NewStyle().Bold().Foreground(tui.Red))
// Gradient write (per-character color interpolation)
grad := tui.NewGradient(tui.Cyan, tui.Magenta)
w.WriteGradient("gradient text", grad)
// Gradient with base style (bold + gradient foreground)
w.WriteGradient("bold gradient", grad, tui.NewStyle().Bold())
w.Close()
}()
```
`WriteStyled(text, style)` wraps text in ANSI style prefix/reset. `WriteGradient(text, gradient, base...)` writes each character with an interpolated gradient foreground; optional base style adds attributes (bold, italic, etc.) and background.
Returns a no-op writer when not in inline mode. Only one stream writer is active at a time; calling `StreamAbove()` again finalizes the previous one. `PrintAbove`/`PrintAboveln` also finalize any active stream before printing.
### PrintAboveElement
`app.PrintAboveElement(el)` renders an element tree at the terminal width and inserts the resulting rows into the inline scrollback as static ANSI text. Works with templ function output. No-op outside inline mode. Must be called from the main event loop. `QueuePrintAboveElement(el)` is the goroutine-safe variant.
`StreamWriter.WriteElement(el)` inserts a rendered element mid-stream. Finalizes the current partial line first.
```go
// Standalone
app.PrintAboveElement(DataTable(rows))
// Mid-stream
w := app.StreamAbove()
w.Write([]byte("Here's the data:\n"))
w.WriteElement(DataTable(rows))
w.Write([]byte("Done.\n"))
w.Close()
```
## Common Layout Patterns
```gsx
// Full-screen with header/content/footer
<div class="flex-col h-full">
<div class="border-single p-1"><span>Header</span></div>
<div class="flex-col grow p-1"><span>Content</span></div>
<div class="border-single p-1"><span>Footer</span></div>
</div>
// Sidebar + main
<div class="flex h-full">
<div class="w-20 border-single flex-col p-1"><span>Sidebar</span></div>
<div class="grow flex-col p-1"><span>Main</span></div>
</div>
// Centered card
<div class="flex items-center justify-center h-full">
<div class="border-rounded p-2 w-40"><span>Centered</span></div>
</div>
// Dashboard grid
<div class="flex-col h-full gap-1">
<div class="flex gap-1 grow">
<div class="grow border-rounded p-1"><span>Panel 1</span></div>
<div class="grow border-rounded p-1"><span>Panel 2</span></div>
</div>
<div class="flex gap-1 grow">
<div class="w-2/3 border-rounded p-1"><span>Wide</span></div>
<div class="grow border-rounded p-1"><span>Narrow</span></div>
</div>
</div>
```
## Modal Example
**Important:** Modals require full-screen mode. They are silently ignored in inline mode (`WithInlineHeight`). To show a modal from an inline app, call `app.EnterAlternateScreen()` first, then `app.ExitAlternateScreen()` when the modal closes.
```gsx
<modal open={s.showConfirm} class="justify-center items-center" backdrop="dim">
<div class="border-rounded p-2 flex-col gap-1 w-40">
<span class="font-bold text-yellow">Confirm?</span>
<button class="px-2 border-rounded focusable" onActivate={s.cancel}>Cancel</button>
<button class="px-2 border-rounded focusable" onActivate={s.confirm}>OK</button>
</div>
</modal>
```
Bottom sheet variant:
```gsx
<modal open={s.showSheet} class="justify-end items-stretch" closeOnBackdropClick={false}>
<div class="border-single p-1 flex gap-4 items-center justify-center">
<span class="font-bold">Action?</span>
<button class="px-2 border-rounded focusable" onActivate={s.cancel}>Cancel</button>
<button class="px-2 border-rounded focusable" onActivate={s.doAction}>Go</button>
</div>
</modal>
```
## Testing
```go
// MockTerminal captures rendering output
term := tui.NewMockTerminal(80, 24)
// MockEventReader provides scripted events
reader := tui.NewMockEventReader(
tui.KeyEvent{Key: tui.KeyRune, Rune: 'a'},
tui.KeyEvent{Key: tui.KeyEscape},
)
// Table-driven test pattern
type tc struct { /* fields */ }
tests := map[string]tc{ "name": { /* values */ } }
for name, tt := range tests {
t.Run(name, func(t *testing.T) { /* test */ })
}
```
## Element Option Functions (Go API)
When building elements programmatically (outside .gsx):
```go
el := tui.New(
tui.WithWidth(30),
tui.WithHeight(10),
tui.WithWidthPercent(50),
tui.WithWidthAuto(),
tui.WithMinWidth(10),
tui.WithMaxWidth(60),
tui.WithDirection(tui.Column),
tui.WithJustify(tui.JustifyCenter),
tui.WithAlign(tui.AlignCenter),
tui.WithGap(2),
tui.WithFlexGrow(1.0),
tui.WithFlexShrink(0),
tui.WithPadding(2),
tui.WithMargin(1),
tui.WithBorder(tui.BorderRounded),
tui.WithBackground(tui.Cyan),
tui.WithText("content"),
tui.WithTextStyle(tui.NewStyle().Bold()),
tui.WithTextAlign(tui.TextAlignCenter),
tui.WithScrollable(tui.ScrollVertical),
tui.WithFocusable(true),
tui.WithHidden(true),
tui.WithTruncate(true),
tui.WithTextGradient(tui.NewGradient(tui.Cyan, tui.Magenta)),
tui.WithBackgroundGradient(tui.NewGradient(tui.Blue, tui.Cyan)),
tui.WithBorderGradient(tui.NewGradient(tui.Cyan, tui.Magenta)),
)
```
## Cross-Component Communication
```gsx
// Producer component
type producer struct {
bus *tui.Events[string]
}
func Producer() *producer {
return &producer{bus: tui.NewEvents[string]("my.topic")}
}
func (p *producer) KeyMap() tui.KeyMap {
return tui.KeyMap{
tui.On(tui.Rune('e'), func(ke tui.KeyEvent) { p.bus.Emit("event!") }),
}
}
// Consumer component (separate, no direct reference to producer)
type consumer struct {
bus *tui.Events[string]
messages *tui.State[[]string]
}
func Consumer() *consumer {
c := &consumer{
bus: tui.NewEvents[string]("my.topic"), // same topic string
messages: tui.NewState([]string{}),
}
c.bus.Subscribe(func(msg string) {
c.messages.Set(append(c.messages.Get(), msg))
})
return c
}
```
## Buffer / Rendering Internals
- Double-buffered character grid (front/back buffers)
- Diff-based rendering: only changed cells are written to terminal
- Each cell stores: Rune, Style, Width (CJK support)
- ANSI escape sequences for cursor movement, colors, text attributes
- Automatic color capability detection and fallback
|