tview/box.go

package tview

import (
	"github.com/gdamore/tcell"
)

// Characters to draw the box border.
const (
	BoxVertBar             = '\u2500'
	BoxHorBar              = '\u2502'
	BoxTopLeftCorner       = '\u250c'
	BoxTopRightCorner      = '\u2510'
	BoxBottomRightCorner   = '\u2518'
	BoxBottomLeftCorner    = '\u2514'
	BoxDbVertBar           = '\u2550'
	BoxDbHorBar            = '\u2551'
	BoxDbTopLeftCorner     = '\u2554'
	BoxDbTopRightCorner    = '\u2557'
	BoxDbBottomRightCorner = '\u255d'
	BoxDbBottomLeftCorner  = '\u255a'
	BoxEllipsis            = '\u2026'
)

// Box implements Rect with a background and optional elements such as a border
// and a title.
type Box struct {
	// The position of the rect.
	x, y, width, height int

	// The box's background color.
	backgroundColor tcell.Color

	// Whether or not a border is drawn, reducing the box's space for content by
	// two in width and height.
	border bool

	// The color of the border.
	borderColor tcell.Color

	// The title. Only visible if there is a border, too.
	title string

	// The color of the title.
	titleColor tcell.Color

	// Provides a way to find out if this box has focus. We always go through
	// this interface because it may be overriden by implementing classes.
	focus Focusable

	// Whether or not this box has focus.
	hasFocus bool
}

// NewBox returns a Box without a border.
func NewBox() *Box {
	b := &Box{
		width:       15,
		height:      10,
		borderColor: tcell.ColorWhite,
		titleColor:  tcell.ColorWhite,
	}
	b.focus = b
	return b
}

// Draw draws this primitive onto the screen.
func (b *Box) Draw(screen tcell.Screen) {
	// Don't draw anything if there is no space.
	if b.width <= 0 || b.height <= 0 {
		return
	}

	def := tcell.StyleDefault

	// Fill background.
	background := def.Background(b.backgroundColor)
	for y := b.y; y < b.y+b.height; y++ {
		for x := b.x; x < b.x+b.width; x++ {
			screen.SetContent(x, y, ' ', nil, background)
		}
	}

	// Draw border.
	if b.border && b.width >= 2 && b.height >= 2 {
		border := background.Foreground(b.borderColor)
		var vertical, horizontal, topLeft, topRight, bottomLeft, bottomRight rune
		if b.focus.HasFocus() {
			vertical = BoxDbVertBar
			horizontal = BoxDbHorBar
			topLeft = BoxDbTopLeftCorner
			topRight = BoxDbTopRightCorner
			bottomLeft = BoxDbBottomLeftCorner
			bottomRight = BoxDbBottomRightCorner
		} else {
			vertical = BoxVertBar
			horizontal = BoxHorBar
			topLeft = BoxTopLeftCorner
			topRight = BoxTopRightCorner
			bottomLeft = BoxBottomLeftCorner
			bottomRight = BoxBottomRightCorner
		}
		for x := b.x + 1; x < b.x+b.width-1; x++ {
			screen.SetContent(x, b.y, vertical, nil, border)
			screen.SetContent(x, b.y+b.height-1, vertical, nil, border)
		}
		for y := b.y + 1; y < b.y+b.height-1; y++ {
			screen.SetContent(b.x, y, horizontal, nil, border)
			screen.SetContent(b.x+b.width-1, y, horizontal, nil, border)
		}
		screen.SetContent(b.x, b.y, topLeft, nil, border)
		screen.SetContent(b.x+b.width-1, b.y, topRight, nil, border)
		screen.SetContent(b.x, b.y+b.height-1, bottomLeft, nil, border)
		screen.SetContent(b.x+b.width-1, b.y+b.height-1, bottomRight, nil, border)

		// Draw title.
		if b.title != "" && b.width >= 4 {
			title := background.Foreground(b.titleColor)
			x := b.x
			for index, ch := range b.title {
				x++
				if x >= b.x+b.width-1 {
					break
				}
				if x == b.x+b.width-2 && index < len(b.title)-1 {
					ch = BoxEllipsis
				}
				screen.SetContent(x, b.y, ch, nil, title)
			}
		}
	}
}

// GetRect returns the current position of the rectangle, x, y, width, and
// height.
func (b *Box) GetRect() (int, int, int, int) {
	return b.x, b.y, b.width, b.height
}

// SetRect sets a new position of the rectangle.
func (b *Box) SetRect(x, y, width, height int) {
	b.x = x
	b.y = y
	b.width = width
	b.height = height
}

// InputHandler returns nil.
func (b *Box) InputHandler() func(event *tcell.EventKey, setFocus func(p Primitive)) {
	return nil
}

// SetBackgroundColor sets the box's background color.
func (b *Box) SetBackgroundColor(color tcell.Color) *Box {
	b.backgroundColor = color
	return b
}

// SetBorder sets the flag indicating whether or not the box should have a
// border.
func (b *Box) SetBorder(show bool) *Box {
	b.border = show
	return b
}

// SetBorderColor sets the box's border color.
func (b *Box) SetBorderColor(color tcell.Color) *Box {
	b.borderColor = color
	return b
}

// SetTitle sets the box's title.
func (b *Box) SetTitle(title string) *Box {
	b.title = title
	return b
}

// SetTitleColor sets the box's title color.
func (b *Box) SetTitleColor(color tcell.Color) *Box {
	b.titleColor = color
	return b
}

// Focus is called when this primitive receives focus.
func (b *Box) Focus(delegate func(p Primitive)) {
	b.hasFocus = true
}

// Blur is called when this primitive loses focus.
func (b *Box) Blur() {
	b.hasFocus = false
}

// HasFocus returns whether or not this primitive has focus.
func (b *Box) HasFocus() bool {
	return b.hasFocus
}