tui/views/view_border.go

package views

import "git.milar.in/milarin/tui"

// BorderView is a tui.Wrapper which draws an ASCII border around its view.
// Be aware that box drawing characters must share the same tui.Style with the next character.
// This can lead to color artifacts when using BorderView with colored styles.
type BorderView struct {
	tui.WrapperTmpl
	Border     BorderBox
	ShowBorder map[tui.Side]bool
}

var _ tui.Wrapper = &BorderView{}

// NewBorderView create a new BorderView which show borders on the given sides around its view.
// If no sides are given, all sides will have a border by default
func NewBorderView(view tui.View, showBorders ...tui.Side) *BorderView {
	v := new(BorderView)
	v.SetView(view)
	v.Border = ThinBorder()

	if len(showBorders) == 0 {
		v.ShowBorder = map[tui.Side]bool{
			tui.SideBottom: true,
			tui.SideTop:    true,
			tui.SideLeft:   true,
			tui.SideRight:  true,
		}
	} else {
		v.ShowBorder = map[tui.Side]bool{}
		for _, border := range showBorders {
			v.ShowBorder[border] = true
		}
	}

	return v
}

func (g *BorderView) Draw(buf *tui.ViewBuffer) {
	viewbuf := buf

	// limit view buffer for child view
	if g.ShowBorder[tui.SideTop] {
		viewbuf = viewbuf.Sub(0, 1, viewbuf.Width(), viewbuf.Height())
	}
	if g.ShowBorder[tui.SideBottom] {
		viewbuf = viewbuf.Sub(0, 0, viewbuf.Width(), viewbuf.Height()-1)
	}
	if g.ShowBorder[tui.SideLeft] {
		viewbuf = viewbuf.Sub(1, 0, viewbuf.Width(), viewbuf.Height())
	}
	if g.ShowBorder[tui.SideRight] {
		viewbuf = viewbuf.Sub(0, 0, viewbuf.Width()-1, viewbuf.Height())
	}

	// draw child view
	g.View().Draw(viewbuf)

	// draw horizontal lines
	for x := 0; x < buf.Width(); x++ {
		if g.ShowBorder[tui.SideTop] {
			buf.Set(x, 0, tui.Rune{Rn: g.Border.Horizontal, Style: g.Style()})
		}
		if g.ShowBorder[tui.SideBottom] {
			buf.Set(x, buf.Height()-1, tui.Rune{Rn: g.Border.Horizontal, Style: g.Style()})
		}
	}

	// draw vertical lines
	for y := 0; y < buf.Height(); y++ {
		if g.ShowBorder[tui.SideLeft] {
			buf.Set(0, y, tui.Rune{Rn: g.Border.Vertical, Style: g.Style()})
		}
		if g.ShowBorder[tui.SideRight] {
			buf.Set(buf.Width()-1, y, tui.Rune{Rn: g.Border.Vertical, Style: g.Style()})
		}
	}

	// draw corners
	if g.ShowBorder[tui.SideTop] {
		if g.ShowBorder[tui.SideLeft] {
			buf.Set(0, 0, tui.Rune{Rn: g.Border.TopLeft, Style: g.Style()})
		}
		if g.ShowBorder[tui.SideRight] {
			buf.Set(buf.Width()-1, 0, tui.Rune{Rn: g.Border.TopRight, Style: g.Style()})
		}
	}
	if g.ShowBorder[tui.SideBottom] {
		if g.ShowBorder[tui.SideLeft] {
			buf.Set(0, buf.Height()-1, tui.Rune{Rn: g.Border.BottomLeft, Style: g.Style()})
		}
		if g.ShowBorder[tui.SideRight] {
			buf.Set(buf.Width()-1, buf.Height()-1, tui.Rune{Rn: g.Border.BottomRight, Style: g.Style()})
		}
	}
}

func (v *BorderView) Layout() (prefWidth, prefHeight int) {
	w, h := v.View().Layout()

	for side, border := range v.ShowBorder {
		if border {
			if side.Horizontal() && w >= 0 {
				w++
			} else if side.Vertical() && h >= 0 {
				h++
			}
		}
	}

	return w, h
}

type BorderBox struct {
	TopLeft     rune
	TopRight    rune
	BottomLeft  rune
	BottomRight rune
	Horizontal  rune
	Vertical    rune
}

func ThickBorder() BorderBox {
	return BorderBox{
		TopLeft:     '┏',
		TopRight:    '┓',
		BottomLeft:  '┗',
		BottomRight: '┛',
		Horizontal:  '━',
		Vertical:    '┃',
	}
}

func ThinBorder() BorderBox {
	return BorderBox{
		TopLeft:     '┌',
		TopRight:    '┐',
		BottomLeft:  '└',
		BottomRight: '┘',
		Horizontal:  '─',
		Vertical:    '│',
	}
}

func DoubleBorder() BorderBox {
	return BorderBox{
		TopLeft:     '╔',
		TopRight:    '╗',
		BottomLeft:  '╚',
		BottomRight: '╝',
		Horizontal:  '═',
		Vertical:    '║',
	}
}