tins2020/control.go

package tins2020

import "github.com/veandco/go-sdl2/sdl"

type Control interface {
	Init(*Context) error
	Arrange(*Context, Rectangle)
	Handle(*Context, sdl.Event) bool
	Render(*Context)
}

type EventContextFn func(*Context)

type EventFn func()

type EventInterfaceFn func(interface{})

func EmptyEvent(fn EventFn) EventContextFn {
	return func(*Context) { fn() }
}

type ControlBase struct {
	Bounds Rectangle

	IsDisabled  bool
	IsMouseOver bool

	OnLeftMouseButtonClick EventContextFn
}

func (b *ControlBase) Arrange(ctx *Context, bounds Rectangle) { b.Bounds = bounds }

func (b *ControlBase) Init(*Context) error { return nil }

func (b *ControlBase) Handle(ctx *Context, event sdl.Event) bool {
	switch e := event.(type) {
	case *sdl.MouseMotionEvent:
		b.IsMouseOver = b.Bounds.IsPointInside(e.X, e.Y)
	case *sdl.MouseButtonEvent:
		if !b.IsDisabled && b.IsMouseOver && e.Button == sdl.BUTTON_LEFT && e.Type == sdl.MOUSEBUTTONDOWN {
			return b.Invoke(ctx, b.OnLeftMouseButtonClick)
		}
	case *sdl.WindowEvent:
		if e.Event == sdl.WINDOWEVENT_LEAVE {
			b.IsMouseOver = false
		}
	}
	return false
}

func (b *ControlBase) Invoke(ctx *Context, fn EventContextFn) bool {
	if fn == nil {
		return false
	}
	fn(ctx)
	return true
}

func (b *ControlBase) Render(*Context) {}