gova-declarative-gui（gova 声明式图形用户界面）

Gova Declarative GUI Framework

Skill by ara.so — Daily 2026 Skills collection.

Gova is a declarative GUI framework for Go that builds native desktop apps for macOS, Windows, and Linux from a single codebase. Views are plain Go structs, state is explicit via a Scope, and go build produces one static binary. Internally powered by Fyne (BSD-3), but the public API is stable and renderer-independent.

Install

go get github.com/nv404/gova@latest

Optional CLI:

go install github.com/nv404/gova/cmd/gova@latest

Prerequisites:

• Go 1.26+
• C toolchain: Xcode CLT (macOS), build-essential + libgl1-mesa-dev (Linux), MinGW (Windows)

Key CLI Commands

Core Concepts

1. Components as Structs

A component is a Go struct implementing Body(s *g.Scope) g.View. Fields on the struct are typed props; zero values are defaults.

package main

import g "github.com/nv404/gova"

type Greeting struct {
    Name string // prop with zero-value default ""
}

func (c Greeting) Body(s *g.Scope) g.View {
    name := c.Name
    if name == "" {
        name = "World"
    }
    return g.Text("Hello, " + name + "!").Font(g.Title)
}

2. Reactive State with Scope

State lives on the *g.Scope passed to Body. No hidden scheduler, no hook-ordering rules.

func (Counter) Body(s *g.Scope) g.View {
    count := g.State(s, 0) // typed signal, initial value 0

    return g.VStack(
        g.Text(count.Format("Count: %d")).Font(g.Title),
        g.HStack(
            g.Button("-", func() { count.Set(count.Get() - 1) }),
            g.Button("+", func() { count.Set(count.Get() + 1) }),
        ).Spacing(g.SpaceMD),
    ).Padding(g.SpaceLG)
}

3. Entry Point

func main() {
    g.Run("My App", g.Component(MyComponent{}))
}

Layout Primitives

// Vertical stack
g.VStack(child1, child2, child3).Spacing(g.SpaceMD).Padding(g.SpaceLG)

// Horizontal stack
g.HStack(child1, child2).Spacing(g.SpaceSM)

// Layered/overlapping stack
g.ZStack(background, foreground)

// Scaffold (app shell with nav, toolbar, etc.)
g.Scaffold(
    g.NavBar("Title"),
    content,
)

Spacing Constants

Built-in Views

g.Text("Hello").Font(g.Title)        // styled text
g.Text("body text").Font(g.Body)

g.Button("Click me", func() { /* handler */ })

g.TextField(value.Get(), func(s string) { value.Set(s) })

g.Toggle(enabled.Get(), func(b bool) { enabled.Set(b) })

g.Image("path/to/image.png")

g.Spacer() // flexible space
g.Divider()

Font Constants

g.Title, g.Headline, g.Body, g.Caption, g.Mono

State Patterns

Basic State

count := g.State(s, 0)
count.Get()        // read
count.Set(42)      // write, triggers re-render
count.Format("Value: %d") // returns formatted string signal

Derived / Computed State

doubled := g.Derived(s, func() int {
    return count.Get() * 2
})

Effects (side effects on state change)

g.Effect(s, func() {
    fmt.Println("count changed to", count.Get())
}, count) // dependencies

Persisted State (survives hot reload)

name := g.PersistedState(s, "user-name", "")

Full Example: Todo App

package main

import g "github.com/nv404/gova"

type Todo struct {
    Text string
    Done bool
}

type TodoApp struct{}

func (TodoApp) Body(s *g.Scope) g.View {
    todos := g.State(s, []Todo{})
    input := g.State(s, "")

    addTodo := func() {
        if input.Get() == "" {
            return
        }
        todos.Set(append(todos.Get(), Todo{Text: input.Get()}))
        input.Set("")
    }

    rows := make([]g.View, 0, len(todos.Get()))
    for i, todo := range todos.Get() {
        i, todo := i, todo // capture loop vars
        rows = append(rows, g.HStack(
            g.Toggle(todo.Done, func(v bool) {
                list := todos.Get()
                list[i].Done = v
                todos.Set(list)
            }),
            g.Text(todo.Text),
        ).Spacing(g.SpaceSM))
    }

    return g.VStack(
        g.Text("Todos").Font(g.Title),
        g.VStack(rows...).Spacing(g.SpaceSM),
        g.HStack(
            g.TextField(input.Get(), func(v string) { input.Set(v) }),
            g.Button("Add", addTodo),
        ).Spacing(g.SpaceSM),
    ).Padding(g.SpaceLG)
}

func main() {
    g.Run("Todo", g.Component(TodoApp{}))
}

Native Dialogs (macOS: NSAlert / NSOpenPanel; other platforms: Fyne fallback)

// Alert dialog
g.Button("Alert", func() {
    g.Alert(g.AlertOptions{
        Title:   "Warning",
        Message: "Something happened.",
        Style:   g.AlertWarning,
    })
})

// Open file dialog
g.Button("Open File", func() {
    path, err := g.OpenFileDialog(g.OpenFileOptions{
        Title:      "Choose a file",
        Extensions: []string{".txt", ".md"},
    })
    if err == nil && path != "" {
        filePath.Set(path)
    }
})

// Save file dialog
g.Button("Save", func() {
    dest, err := g.SaveFileDialog(g.SaveFileOptions{
        Title:           "Save As",
        DefaultFilename: "output.txt",
    })
    if err == nil && dest != "" {
        // write to dest
    }
})

Platform Integration (macOS Dock)

// Dock badge (macOS)
g.DockBadge("3")
g.DockBadge("") // clear badge

// Dock progress (macOS)
g.DockProgress(0.75) // 0.0–1.0
g.DockProgress(-1)   // hide

// Dock menu (macOS)
g.SetDockMenu([]g.MenuItem{
    {Label: "New Window", Action: func() { /* ... */ }},
    {Label: "Preferences", Action: func() { /* ... */ }},
})

Theming and Colors

// Dark/light toggle
g.Button("Toggle Theme", func() {
    if g.CurrentTheme() == g.ThemeDark {
        g.SetTheme(g.ThemeLight)
    } else {
        g.SetTheme(g.ThemeDark)
    }
})

// Semantic colors in custom views
g.Text("Primary").Color(g.ColorPrimary)
g.Text("Secondary").Color(g.ColorSecondary)
g.Text("Danger").Color(g.ColorDanger)

Component Composition with Viewable

type Card struct {
    Title   string
    Content g.View
}

func (c Card) Body(s *g.Scope) g.View {
    return g.VStack(
        g.Text(c.Title).Font(g.Headline),
        g.Divider(),
        c.Content,
    ).Padding(g.SpaceMD)
}

// Usage
g.Component(Card{
    Title:   "My Card",
    Content: g.Text("Card body text"),
})

Navigation / Multi-View

type NotesApp struct{}

func (NotesApp) Body(s *g.Scope) g.View {
    selected := g.State(s, "list")

    switch selected.Get() {
    case "detail":
        return g.Component(DetailView{OnBack: func() { selected.Set("list") }})
    default:
        return g.Component(ListView{OnSelect: func() { selected.Set("detail") }})
    }
}

App Icon at Runtime

func main() {
    app := g.NewApp("My App")
    app.SetIcon("assets/icon.png") // set before Run
    app.Run(g.Component(MyComponent{}))
}

Hot Reload with PersistedState

When using gova dev, use g.PersistedState to keep UI state across rebuilds:

func (MyApp) Body(s *g.Scope) g.View {
    // survives hot reload, lost on full restart
    activeTab := g.PersistedState(s, "active-tab", "home")
    // ...
}

Project Structure (recommended)

myapp/
├── main.go          # g.Run entry point
├── components/
│   ├── header.go
│   └── sidebar.go
├── views/
│   ├── home.go
│   └── settings.go
├── assets/
│   └── icon.png
└── go.mod

Platform Support Matrix

Troubleshooting

cgo: C compiler not found

• macOS: xcode-select --install
• Linux: sudo apt install build-essential libgl1-mesa-dev
• Windows: Install MinGW-w64 and add to PATH

go build fails with OpenGL errors on Linux

sudo apt install libgl1-mesa-dev xorg-dev

Hot reload not picking up changes

• Ensure you're using gova dev, not go run
• Confirm .go files are in a directory watched by gova dev./path

Binary is large (~32 MB)

• Strip symbols: go build -ldflags "-s -w" -o./bin/myapp
• Result: ~23 MB. This is expected — Fyne (OpenGL renderer) is bundled.

State not updating the UI

• Always call count.Set(...) — mutating a slice/map in place without Set won't trigger re-render
• For slices: copy, modify, then set: list:= todos.Get(); list[i] = newVal; todos.Set(list)

API breakage (pre-1.0)

• Pin a specific tag: go get github.com/nv404/gova@v0.x.y
• Check the CHANGELOG before upgrading

Useful Links

• Docs: https://gova.dev
• Getting started: https://gova.dev/docs/getting-started/installation
• State & effects: https://gova.dev/docs/state/state
• Native dialogs: https://gova.dev/docs/overlays/native-dialogs
• CLI reference: https://gova.dev/docs/cli/overview
• pkg.go.dev: https://pkg.go.dev/github.com/nv404/gova