ginger/gim/line.go

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1.9 KiB
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package main
import (
"github.com/mediocregopher/ginger/gim/geo"
"github.com/mediocregopher/ginger/gim/terminal"
)
type line struct {
from, to *box
fromI, toI int
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body string
}
// given the "primary" direction the line should be headed, picks 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)
func secondaryDir(flowDir, start, end geo.XY) geo.XY {
var perpDir geo.XY
perpDir[0], perpDir[1] = flowDir[1], flowDir[0]
return end.Sub(start).Mul(perpDir.Abs()).Unit()
}
func (l line) draw(buf *terminal.Buffer, flowDir, secFlowDir geo.XY) {
from, to := *(l.from), *(l.to)
start := from.rect().Edge(flowDir, secFlowDir)[0].Add(secFlowDir.Scale(l.fromI*2 + 1))
end := to.rect().Edge(flowDir.Inv(), secFlowDir)[0].Add(secFlowDir.Scale(l.toI*2 + 1))
dirSec := secondaryDir(flowDir, start, end)
mid := start.Midpoint(end, rounder)
along := func(xy, dir geo.XY) int {
if dir[0] != 0 {
return xy[0]
}
return xy[1]
}
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// collect the points along the line into an array
var pts []geo.XY
midPrim := along(mid, flowDir)
endSec := along(end, dirSec)
for curr := start; curr != end; {
pts = append(pts, curr)
if prim := along(curr, flowDir); prim == midPrim {
if sec := along(curr, dirSec); sec != endSec {
curr = curr.Add(dirSec)
continue
}
}
curr = curr.Add(flowDir)
}
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// draw each point
for i, pt := range pts {
var r rune
switch {
case i == 0:
r = terminal.SingleLine.Perpendicular(flowDir)
case i == len(pts)-1:
r = terminal.SingleLine.Arrow(flowDir)
default:
prev, next := pts[i-1], pts[i+1]
r = terminal.SingleLine.Segment(prev.Sub(pt), next.Sub(pt))
}
buf.SetPos(pt)
buf.WriteRune(r)
}
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// draw the body
if l.body != "" {
bodyPos := mid.Add(geo.Left.Scale(len(l.body) / 2))
buf.SetPos(bodyPos)
buf.WriteString(l.body)
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}
}