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// Copyright 2010 The draw2d Authors. All rights reserved.
// created: 13/12/2010 by Laurent Le Goff
package draw2d
type Cap int
const (
RoundCap Cap = iota
ButtCap
SquareCap
)
type Join int
const (
BevelJoin Join = iota
RoundJoin
MiterJoin
)
type LineStroker struct {
Next VertexConverter
HalfLineWidth float64
Cap Cap
Join Join
vertices []float64
rewind []float64
x, y, nx, ny float64
command VertexCommand
}
func NewLineStroker(c Cap, j Join, converter VertexConverter) *LineStroker {
l := new(LineStroker)
l.Next = converter
l.HalfLineWidth = 0.5
l.vertices = make([]float64, 0, 256)
l.rewind = make([]float64, 0, 256)
l.Cap = c
l.Join = j
l.command = VertexNoCommand
return l
}
func (l *LineStroker) NextCommand(command VertexCommand) {
l.command = command
if command == VertexStopCommand {
l.Next.NextCommand(VertexStartCommand)
for i, j := 0, 1; j < len(l.vertices); i, j = i+2, j+2 {
l.Next.Vertex(l.vertices[i], l.vertices[j])
l.Next.NextCommand(VertexNoCommand)
}
for i, j := len(l.rewind)-2, len(l.rewind)-1; j > 0; i, j = i-2, j-2 {
l.Next.NextCommand(VertexNoCommand)
l.Next.Vertex(l.rewind[i], l.rewind[j])
}
if len(l.vertices) > 1 {
l.Next.NextCommand(VertexNoCommand)
l.Next.Vertex(l.vertices[0], l.vertices[1])
}
l.Next.NextCommand(VertexStopCommand)
// reinit vertices
l.vertices = l.vertices[0:0]
l.rewind = l.rewind[0:0]
l.x, l.y, l.nx, l.ny = 0, 0, 0, 0
}
}
func (l *LineStroker) Vertex(x, y float64) {
switch l.command {
case VertexNoCommand:
l.line(l.x, l.y, x, y)
case VertexJoinCommand:
l.joinLine(l.x, l.y, l.nx, l.ny, x, y)
case VertexStartCommand:
l.x, l.y = x, y
case VertexCloseCommand:
l.line(l.x, l.y, x, y)
l.joinLine(l.x, l.y, l.nx, l.ny, x, y)
l.closePolygon()
}
l.command = VertexNoCommand
}
func (l *LineStroker) appendVertex(vertices ...float64) {
s := len(vertices) / 2
if len(l.vertices)+s >= cap(l.vertices) {
v := make([]float64, len(l.vertices), cap(l.vertices)+128)
copy(v, l.vertices)
l.vertices = v
v = make([]float64, len(l.rewind), cap(l.rewind)+128)
copy(v, l.rewind)
l.rewind = v
}
copy(l.vertices[len(l.vertices):len(l.vertices)+s], vertices[:s])
l.vertices = l.vertices[0 : len(l.vertices)+s]
copy(l.rewind[len(l.rewind):len(l.rewind)+s], vertices[s:])
l.rewind = l.rewind[0 : len(l.rewind)+s]
}
func (l *LineStroker) closePolygon() {
if len(l.vertices) > 1 {
l.appendVertex(l.vertices[0], l.vertices[1], l.rewind[0], l.rewind[1])
}
}
func (l *LineStroker) line(x1, y1, x2, y2 float64) {
dx := (x2 - x1)
dy := (y2 - y1)
d := vectorDistance(dx, dy)
if d != 0 {
nx := dy * l.HalfLineWidth / d
ny := -(dx * l.HalfLineWidth / d)
l.appendVertex(x1+nx, y1+ny, x2+nx, y2+ny, x1-nx, y1-ny, x2-nx, y2-ny)
l.x, l.y, l.nx, l.ny = x2, y2, nx, ny
}
}
func (l *LineStroker) joinLine(x1, y1, nx1, ny1, x2, y2 float64) {
dx := (x2 - x1)
dy := (y2 - y1)
d := vectorDistance(dx, dy)
if d != 0 {
nx := dy * l.HalfLineWidth / d
ny := -(dx * l.HalfLineWidth / d)
/* l.join(x1, y1, x1 + nx, y1 - ny, nx, ny, x1 + ny2, y1 + nx2, nx2, ny2)
l.join(x1, y1, x1 - ny1, y1 - nx1, nx1, ny1, x1 - ny2, y1 - nx2, nx2, ny2)*/
l.appendVertex(x1+nx, y1+ny, x2+nx, y2+ny, x1-nx, y1-ny, x2-nx, y2-ny)
l.x, l.y, l.nx, l.ny = x2, y2, nx, ny
}
}
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