ginger/gim/terminal/shape.go

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package terminal
import (
"fmt"
"strings"
"github.com/mediocregopher/ginger/gim/geo"
)
// SingleLine is a set of single-pixel-width lines.
var SingleLine = LineStyle{
Horiz: '─',
Vert: '│',
TopLeft: '┌',
TopRight: '┐',
BottomLeft: '└',
BottomRight: '┘',
PerpUp: '┴',
PerpDown: '┬',
PerpLeft: '┤',
PerpRight: '├',
ArrowUp: '^',
ArrowDown: 'v',
ArrowLeft: '<',
ArrowRight: '>',
}
// LineStyle defines a set of characters to use together when drawing lines and
// corners.
type LineStyle struct {
Horiz, Vert rune
// Corner characters, identified as corners of a rectangle
TopLeft, TopRight, BottomLeft, BottomRight rune
// Characters for a straight segment a perpendicular attached
PerpUp, PerpDown, PerpLeft, PerpRight rune
// Characters for pointing arrows
ArrowUp, ArrowDown, ArrowLeft, ArrowRight rune
}
// Segment takes two different directions (i.e. geo.Up/Down/Left/Right) and
// returns the line character which points in both of those directions.
//
// For example, SingleLine.Segment(geo.Up, geo.Left) returns '┘'.
func (ls LineStyle) Segment(a, b geo.XY) rune {
inner := func(a, b geo.XY) rune {
type c struct{ a, b geo.XY }
switch (c{a, b}) {
case c{geo.Up, geo.Down}:
return ls.Vert
case c{geo.Left, geo.Right}:
return ls.Horiz
case c{geo.Down, geo.Right}:
return ls.TopLeft
case c{geo.Down, geo.Left}:
return ls.TopRight
case c{geo.Up, geo.Right}:
return ls.BottomLeft
case c{geo.Up, geo.Left}:
return ls.BottomRight
default:
return 0
}
}
if r := inner(a, b); r != 0 {
return r
} else if r = inner(b, a); r != 0 {
return r
}
panic(fmt.Sprintf("invalid LineStyle.Segment directions: %v, %v", a, b))
}
// Perpendicular returns the line character for a perpendicular segment
// traveling in the given direction.
func (ls LineStyle) Perpendicular(dir geo.XY) rune {
switch dir {
case geo.Up:
return ls.PerpUp
case geo.Down:
return ls.PerpDown
case geo.Left:
return ls.PerpLeft
case geo.Right:
return ls.PerpRight
default:
panic(fmt.Sprintf("invalid LineStyle.Perpendicular direction: %v", dir))
}
}
// Arrow returns the arrow character for an arrow pointing in the given
// direction.
func (ls LineStyle) Arrow(dir geo.XY) rune {
switch dir {
case geo.Up:
return ls.ArrowUp
case geo.Down:
return ls.ArrowDown
case geo.Left:
return ls.ArrowLeft
case geo.Right:
return ls.ArrowRight
default:
panic(fmt.Sprintf("invalid LineStyle.Arrow direction: %v", dir))
}
}
// DrawRect draws the given Rect to the Buffer with the given LineStyle. The
// Rect's TopLeft field is used for its position.
//
// If Rect's Size is not at least 2x2 this does nothing.
func (b *Buffer) DrawRect(r geo.Rect, ls LineStyle) {
if r.Size[0] < 2 || r.Size[1] < 2 {
return
}
horiz := strings.Repeat(string(ls.Horiz), r.Size[0]-2)
b.SetPos(r.TopLeft)
b.WriteRune(ls.TopLeft)
b.WriteString(horiz)
b.WriteRune(ls.TopRight)
for i := 0; i < r.Size[1]-2; i++ {
b.SetPos(r.TopLeft.Add(geo.XY{0, i + 1}))
b.WriteRune(ls.Vert)
b.SetPos(r.TopLeft.Add(geo.XY{r.Size[0] - 1, i + 1}))
b.WriteRune(ls.Vert)
}
b.SetPos(r.TopLeft.Add(geo.XY{0, r.Size[1] - 1}))
b.WriteRune(ls.BottomLeft)
b.WriteString(horiz)
b.WriteRune(ls.BottomRight)
}
// DrawLine draws a line from the start point to the ending one, primarily
// moving in the given direction, using the given LineStyle to do so.
func (b *Buffer) DrawLine(start, end, dir geo.XY, ls LineStyle) {
// given the "primary" direction the line should be headed, pick a possible
// secondary one which may be used to detour along the path in order to
// reach the destination (in the case that the two boxes are diagonal from
// each other)
var perpDir geo.XY
perpDir[0], perpDir[1] = dir[1], dir[0]
dirSec := end.Sub(start).Mul(perpDir.Abs()).Unit()
mid := start.Midpoint(end)
along := func(xy, dir geo.XY) int {
if dir[0] != 0 {
return xy[0]
}
return xy[1]
}
// collect the points along the line into an array
var pts []geo.XY
var curr geo.XY
midPrim := along(mid, dir)
endSec := along(end, dirSec)
for curr = start; curr != end; {
pts = append(pts, curr)
if prim := along(curr, dir); prim == midPrim {
if sec := along(curr, dirSec); sec != endSec {
curr = curr.Add(dirSec)
continue
}
}
curr = curr.Add(dir)
}
pts = append(pts, curr) // appending end
// draw each point
for i, pt := range pts {
var prev, next geo.XY
switch {
case i == 0:
prev = pt.Add(dir.Inv())
next = pts[i+1]
case i == len(pts)-1:
prev = pts[i-1]
next = pt.Add(dir)
default:
prev, next = pts[i-1], pts[i+1]
}
b.SetPos(pt)
b.WriteRune(ls.Segment(prev.Sub(pt), next.Sub(pt)))
}
}