# GIOWrap

An experimental wrapper package for the Gio immediate mode GUI, designed to reduce
boilerplate.

```
go run ~/go/src/git.wow.st/gmp/giowrap/cmd/hello/main.go
```

The basic concept is to define a `Context` type that contains the Gio variables
required for layout and drawing. `Context` contains a pointer to `app.Window` and
`ui.Ops` so that, once layout is complete, you can call `Context.Draw()` to draw
your objects in your window.

The following types and functions are defined in order to transform a `Context`
variable during layout:

```go
type Layout func(Context) Context

type Widget interface {
	Layout(Context) Context
}

type WidgetCombinator func(...Widget) Widget

type Enclosure interface {
	Begin(Context) Context
	End(Context) Context
}

func Enclose(e Enclosure, w ...Widget) Widget { ... }
```

The giowrap package also includes a private package-global variable called
extra that is a []interface{}, allowing arbitrary data to be maintained by
UI elements. Elements can request access to the structure when they are
allocated and they are returned a unique integer index into the slice. This
can be used, for example, to define themes, and control
the operation of a `WidgetCombinator` during operation. For example:

```go
type fWidget struct { l Layout }
func NewfWidget(l layout) fWidget { return fWidget{ l: l } }

func Flexible(v float32) Widget {
	return NewfWidget(func(ctx Context) Context {
		extra.data[extra.cur].(*FlexOpts).flexible = v
		return ctx
	})
}

...
	ctx = myFlex(
			w1,
			giowrap.Flexible(0.5),
			w2,
			giowrap.Flexible(1),
			w3,
		).Layout(ctx)
	ctx.Draw()
...
```