grue

type Align int

type Base struct {
	Theme      *Theme
	Rect       Rect
	Text       string
	TextAlign  Align
	Tooltip    string
	Disabled   bool
	Image      string
	ImageAlign Align

	// If true, widget is invisible (but children are).
	// OnDraw is still called and can paint.
	Phantom bool
}

type Button int

type Charset struct {
}

type ImageSheetConfig struct {
	// Either atlas or file should be set.
	// If atlas is nil, file is used as filename to load image.
	Atlas image.Image
	// File is the name of the image file to load.
	File string `json:"file"`
	// Sheets containing continuous line of uniform sized subimages.
	Sheets []SheetConfig `json:"sheets"`
}

type Interactive struct {
	OnMouseIn    func()
	OnMouseOut   func()
	OnMouseMove  func()
	OnMouseDown  func(button Button)
	OnMouseUp    func(button Button)
	OnMouseClick func(button Button)
	OnMouseWheel func()
	OnKeys       func() bool
}

type Panel struct {
	Parent   Widget
	Children []Widget

	// Virt is interface by which virtual calls can be made,
	// i. e. this panel might be embedded to button, then
	// Render calls panel's version, but virt.Render will call
	// button's one.
	// Of course, every embedding type must assign itself
	// to virt to make this work.
	// WARNING: Virt is required to be used in place of
	// Widget interface values in any of Panel and
	// it's derivative types methods. Otherwise "slicing" will
	// happen and Widget will be in fact Panel (or the type that
	// used pointer to self when creating value of Widget type)
	// instead of derivative type. This may have some side-effects,
	// although comparision is already handled by Equals method.
	Virt Widget

	// Base is panel's base.
	Base

	// True if pointer is inside the widget
	PointerInside bool

	// Interactive provides response to input events.
	Interactive

	// Custom drawing function. Called from Paint.
	OnDraw func()

	// Graphics surface.
	Surface Surface
}

type PlainRect struct {
	BackColor   color.Color
	BorderSize  float64
	BorderInset float64
	BorderColor color.Color
}

type PushButton struct {
	*Panel
	Pressed bool

	OnPress func()
}

type Rect struct {
	Min, Max Vec
}

type SheetConfig struct {
	XOffset float64  `json:"x_offset"`
	YOffset float64  `json:"y_offset"`
	W       float64  `json:"width"`
	H       float64  `json:"height"`
	Names   []string `json:"names"`
}

type Surface interface {
	// Run main loop (blocking)
	Run()

	// Set function to be called at every screen update.
	SetEvents(handler func())

	// Get root widget to use as parent to other UI elements
	Root() Widget

	// Set current tooltip
	SetToolTip(tooltip string)

	// Show widget as popup. Popups are closed if mouse is
	// clicked outside of any popup widget, or
	// if escape is pressed. Mouse click that closed popup
	// is not otherwise processed.
	PopUp(w Widget)

	// Close popups added after this widget.
	// If passed nil, closes all popups.
	PopDownTo(w Widget)

	// Returns true, if there are any active popups.
	IsPopUpMode() bool

	// Returns true, if widget or any of its parents is popup.
	IsPopUp(w Widget) bool

	// PopUpUnder returns widget from popup list (if any),
	// if it's under pointer coords
	PopUpUnder(pos Vec) Widget

	// Draw functions
	DrawFillRect(r Rect, col color.Color)
	DrawRect(r Rect, col color.Color, thick float64)

	// Font is a font name that was previously initialized.
	// alh, alv -- horizontal and vertical text alignment (see Aling type)
	DrawText(msg, font string, r Rect, col color.Color, al Align)

	GetTextRect(msg, font string) Rect

	// Draws image centered around pos.
	DrawImage(name string, pos Vec, col color.Color)

	// Draws image aligned relative to rect.
	DrawImageAligned(name string, rect Rect, al Align, col color.Color)

	// Draw image into target rectangle.
	DrawImageStretched(name string, rect Rect, col color.Color)

	// Mouse & keyboard
	MousePos() Vec
	PrevMousePos() Vec
	ClickMousePos() Vec
	JustPressed(button Button) bool
	JustReleased(button Button) bool
	MouseScroll() Vec

	// Load and init TTF font that will be known under given name
	InitTTF(fontName, fileName string, size float64, charset Charset) error

	// Load and init images from sheet described by JSON file
	InitImages(configFileName string) error

	// Get size of the previously loaded image
	GetImageSize(name string) (Vec, error)

	// Init images from sheet described by config structure.
	// Images will be named as described in configuration.
	// DrawImage can be used with corresponding image names.
	// If JSON sheets configuration file exists,
	// you may want to use InitImages method.
	InitImageSheets(config ImageSheetConfig) error

	SetTheme(theme Theme)
	GetTheme() *Theme
}

type SurfaceConfig struct {
	// Window specific options -- only applicable
	// to primary surface.
	Title          string
	WindowGeometry Rect
	IconFile       string
	FPS            int

	// Surface options
	PixelSize float64
	BackColor color.Color
}

type TexturedPanel struct {
	// Prefix of image name for the parts of panel.
	// By adding -tl, -t, -tr,
	//           -l,  -c, -r,
	//           -bl, -b, -br
	// to this, image name of the part is formed.
	ImagePrefix string

	// Use tiling instead of stretching for these parts:
	// l, r, c, t, b.
	TileHorizontal bool
	TileVertical   bool

	// Set this to some color to tint texture.
	Color color.Color
}

type Theme struct {
	// Font name used for titles (panels, buttons, etc)
	TitleFont         string
	TooltipFont       string
	TextColor         color.Color
	DisabledTextColor color.Color
	TooltipColor      color.Color

	// Pad to insert between border and text in autosized panels
	Pad float64

	// Drawers
	Drawers map[ThemeDrawerKey]ThemeDrawer
}

type ThemeDrawer interface {
	Draw(s Surface, rect Rect)
}

type ThemeDrawerKey string

type Vec struct {
	X, Y float64
}

type Widget interface {
	// This should be redefined in derived types
	Paint()

	// Panel implementation of these should be sufficient
	GetPanel() *Panel
	Equals(w Widget) bool
	Close()
	Foster(ch Widget)
	Render()
	ProcessMouse(wu Widget)
	ProcessKeys()
	WidgetUnder(pos Vec) Widget
	GlobalRect() Rect
	Place(rel Vec)
	// contains filtered or unexported methods
}