90 lines
2.4 KiB
Go
90 lines
2.4 KiB
Go
// Copyright 2010 The draw2d Authors. All rights reserved.
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// created: 13/12/2010 by Laurent Le Goff
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package draw2d
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type DashVertexConverter struct {
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command VertexCommand
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next VertexConverter
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x, y, distance float64
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dash []float64
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currentDash int
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dashOffset float64
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}
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func NewDashConverter(dash []float64, dashOffset float64, converter VertexConverter) *DashVertexConverter {
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var dasher DashVertexConverter
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dasher.dash = dash
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dasher.currentDash = 0
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dasher.dashOffset = dashOffset
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dasher.next = converter
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return &dasher
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}
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func (dasher *DashVertexConverter) NextCommand(cmd VertexCommand) {
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dasher.command = cmd
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if dasher.command == VertexStopCommand {
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dasher.next.NextCommand(VertexStopCommand)
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}
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}
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func (dasher *DashVertexConverter) Vertex(x, y float64) {
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switch dasher.command {
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case VertexStartCommand:
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dasher.start(x, y)
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default:
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dasher.lineTo(x, y)
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}
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dasher.command = VertexNoCommand
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}
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func (dasher *DashVertexConverter) start(x, y float64) {
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dasher.next.NextCommand(VertexStartCommand)
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dasher.next.Vertex(x, y)
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dasher.x, dasher.y = x, y
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dasher.distance = dasher.dashOffset
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dasher.currentDash = 0
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}
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func (dasher *DashVertexConverter) lineTo(x, y float64) {
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rest := dasher.dash[dasher.currentDash] - dasher.distance
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for rest < 0 {
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dasher.distance = dasher.distance - dasher.dash[dasher.currentDash]
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dasher.currentDash = (dasher.currentDash + 1) % len(dasher.dash)
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rest = dasher.dash[dasher.currentDash] - dasher.distance
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}
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d := distance(dasher.x, dasher.y, x, y)
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for d >= rest {
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k := rest / d
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lx := dasher.x + k*(x-dasher.x)
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ly := dasher.y + k*(y-dasher.y)
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if dasher.currentDash%2 == 0 {
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// line
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dasher.next.Vertex(lx, ly)
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} else {
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// gap
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dasher.next.NextCommand(VertexStopCommand)
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dasher.next.NextCommand(VertexStartCommand)
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dasher.next.Vertex(lx, ly)
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}
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d = d - rest
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dasher.x, dasher.y = lx, ly
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dasher.currentDash = (dasher.currentDash + 1) % len(dasher.dash)
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rest = dasher.dash[dasher.currentDash]
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}
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dasher.distance = d
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if dasher.currentDash%2 == 0 {
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// line
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dasher.next.Vertex(x, y)
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} else {
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// gap
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dasher.next.NextCommand(VertexStopCommand)
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dasher.next.NextCommand(VertexStartCommand)
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dasher.next.Vertex(x, y)
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}
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if dasher.distance >= dasher.dash[dasher.currentDash] {
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dasher.distance = dasher.distance - dasher.dash[dasher.currentDash]
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dasher.currentDash = (dasher.currentDash + 1) % len(dasher.dash)
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}
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dasher.x, dasher.y = x, y
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}
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