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package svg
import (
"errors"
"fmt"
"html"
"math"
"strings"
"time"
"b612.me/astro/internal/svgasset"
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"b612.me/astro/internal/svgchart"
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"b612.me/astro/moon"
)
const (
localPlanetOccultationSVGDefaultWidth = 1040
localPlanetOccultationSVGDefaultHeight = 760
localPlanetOccultationSVGMinimumWidth = 760
localPlanetOccultationSVGMinimumHeight = 600
localPlanetOccultationSVGDefaultStep = 2 * time . Minute
)
// ErrInvalidLocalPlanetOccultationSVGOptions 表示本地行星图表选项无效。
// ErrInvalidLocalPlanetOccultationSVGOptions reports invalid local planetary chart options.
var ErrInvalidLocalPlanetOccultationSVGOptions = errors . New ( "invalid local planetary occultation SVG options" )
// ErrInvalidLocalPlanetOccultationInfo 表示固定地点行星事件数据格式错误。
// ErrInvalidLocalPlanetOccultationInfo reports malformed fixed-site planetary event data.
var ErrInvalidLocalPlanetOccultationInfo = errors . New ( "invalid local planetary occultation info" )
// LocalPlanetOccultationSVGOptions 控制固定地点月球与行星盘面图。
// LocalPlanetOccultationSVGOptions controls a fixed-site Moon-planet disk chart.
type LocalPlanetOccultationSVGOptions struct {
// Width 和 Height 是 SVG 画布尺寸；非正值使用默认值。
// Width and Height are SVG canvas dimensions. Values <= 0 use defaults.
Width int
Height int
// Step 是月心行星轨迹请求采样步长；零值使用两分钟，负值无效，正值小于一秒时提升到一秒。长事件可能增大实际步长，以保持基础轨迹在有界采样预算内。
// Step is the requested Moon-centered planetary-track sampling step. Zero uses two minutes; negative values are invalid. Positive values below one second are raised to one second, and long events may use a larger effective step to keep the base track within its bounded sample budget.
Step time . Duration
// 空文本字段使用本地化的自动标签。
// Empty text fields use localized automatic labels.
Title string
SummaryText string
GreatestText string
OverviewTitle string
PhasePanelsTitle string
ContactsTitle string
DirectionText string
FooterNote string
// Language 为 "en" 时使用英文，其他值使用中文。
// Language uses English for "en" and Chinese for every other value.
Language string
// Location 控制显示的事件时刻；nil 使用 UTC+8。
// Location controls displayed event times. Nil uses UTC+8.
Location * time . Location
}
type localPlanetOccultationEventFrame struct {
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label string
name string
time time . Time
hidden bool
frame moon . PlanetOccultationDiagramFrame
appearance localOccultationMoonAppearance
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}
// FindLocalPlanetOccultationSVGs 搜索固定观测地点，并渲染请求时间窗口内的每次有限盘面行星月掩。空切片表示没有本地事件。
// FindLocalPlanetOccultationSVGs searches one fixed observing site and renders every finite-disk planetary occultation in the requested time window. An empty slice means no local event.
func FindLocalPlanetOccultationSVGs (
start , end time . Time ,
planet moon . OccultationPlanet ,
longitude , latitude , height float64 ,
searchOptions moon . OccultationSearchOptions ,
options LocalPlanetOccultationSVGOptions ,
) ([] string , error ) {
if err := validateLocalPlanetOccultationSVGOptions ( options ); err != nil {
return nil , err
}
events , err := moon . FindPlanetOccultations (
start , end , planet , longitude , latitude , height , searchOptions ,
)
if err != nil {
return nil , err
}
diagrams := make ([] string , 0 , len ( events ))
for _ , event := range events {
diagram , renderErr := LocalPlanetOccultationSVG ( event , options )
if renderErr != nil {
return nil , renderErr
}
diagrams = append ( diagrams , diagram )
}
return diagrams , nil
}
// LocalPlanetOccultationSVG 渲染已求解的固定地点行星月掩的月心轨迹及适用的 C1-C4 阶段面板；不会运行事件搜索。
// LocalPlanetOccultationSVG renders an already solved fixed-site planetary occultation as a Moon-centered track with all applicable C1-C4 stage panels. It does not run the event search.
func LocalPlanetOccultationSVG (
info moon . PlanetOccultationInfo ,
options LocalPlanetOccultationSVGOptions ,
) ( string , error ) {
if err := validateLocalPlanetOccultationInfo ( info ); err != nil {
return "" , err
}
if err := validateLocalPlanetOccultationSVGOptions ( options ); err != nil {
return "" , err
}
options = normalizeLocalPlanetOccultationSVGOptions ( options )
diagram := moon . PlanetOccultationDiagram ( info , moon . PlanetOccultationDiagramOptions {
StepDays : options . Step . Hours () / 24 ,
})
if len ( diagram . Frames ) == 0 {
return "" , fmt . Errorf ( "%w: diagram geometry is unavailable" , ErrInvalidLocalPlanetOccultationInfo )
}
return renderLocalPlanetOccultationSVG ( info , diagram , options ), nil
}
func validateLocalPlanetOccultationSVGOptions ( options LocalPlanetOccultationSVGOptions ) error {
if options . Width > 0 && options . Width < localPlanetOccultationSVGMinimumWidth {
return fmt . Errorf ( "%w: width must be zero or at least %d" , ErrInvalidLocalPlanetOccultationSVGOptions , localPlanetOccultationSVGMinimumWidth )
}
if options . Height > 0 && options . Height < localPlanetOccultationSVGMinimumHeight {
return fmt . Errorf ( "%w: height must be zero or at least %d" , ErrInvalidLocalPlanetOccultationSVGOptions , localPlanetOccultationSVGMinimumHeight )
}
if options . Step < 0 {
return fmt . Errorf ( "%w: step cannot be negative" , ErrInvalidLocalPlanetOccultationSVGOptions )
}
return nil
}
func validateLocalPlanetOccultationInfo ( info moon . PlanetOccultationInfo ) error {
if err := info . Planet . Validate (); err != nil {
return fmt . Errorf ( "%w: %v" , ErrInvalidLocalPlanetOccultationInfo , err )
}
if err := info . Observer . Validate (); err != nil {
return fmt . Errorf ( "%w: %v" , ErrInvalidLocalPlanetOccultationInfo , err )
}
if ! info . ContactsComplete || info . ExternalImmersion . IsZero () || info . Greatest . IsZero () || info . ExternalEmersion . IsZero () {
return fmt . Errorf ( "%w: complete external contacts and greatest time are required" , ErrInvalidLocalPlanetOccultationInfo )
}
if info . Greatest . Before ( info . ExternalImmersion ) || info . ExternalEmersion . Before ( info . Greatest ) {
return fmt . Errorf ( "%w: event times must be ordered" , ErrInvalidLocalPlanetOccultationInfo )
}
if info . Type == moon . OccultationTotal {
if ! info . HasInternalContacts || info . InternalImmersion . IsZero () || info . InternalEmersion . IsZero () ||
! info . InternalImmersion . After ( info . ExternalImmersion ) || ! info . InternalImmersion . Before ( info . Greatest ) ||
! info . InternalEmersion . After ( info . Greatest ) || ! info . InternalEmersion . Before ( info . ExternalEmersion ) {
return fmt . Errorf ( "%w: a total event requires ordered C2 and C3 contacts" , ErrInvalidLocalPlanetOccultationInfo )
}
} else if info . Type != moon . OccultationPartial && info . Type != moon . OccultationGrazing {
return fmt . Errorf ( "%w: unsupported finite-disk geometry %q" , ErrInvalidLocalPlanetOccultationInfo , info . Type )
} else if info . HasInternalContacts || ! info . InternalImmersion . IsZero () || ! info . InternalEmersion . IsZero () {
return fmt . Errorf ( "%w: partial and grazing events cannot contain internal contacts" , ErrInvalidLocalPlanetOccultationInfo )
}
if ! starOccultationFinite ( info . MinimumSeparationArcsec ) || info . MinimumSeparationArcsec < 0 ||
! starOccultationFinite ( info . MoonSemidiameterArcsec ) || info . MoonSemidiameterArcsec <= 0 ||
! starOccultationFinite ( info . PlanetSemidiameterArcsec ) || info . PlanetSemidiameterArcsec <= 0 ||
info . PlanetSemidiameterArcsec >= info . MoonSemidiameterArcsec ||
! starOccultationFinite ( info . PositionAngleDeg ) ||
! starOccultationFinite ( info . MoonAltitudeAtGreatest ) ||
! starOccultationFinite ( info . MoonAzimuthAtGreatest ) {
return fmt . Errorf ( "%w: event geometry must be finite" , ErrInvalidLocalPlanetOccultationInfo )
}
return nil
}
func normalizeLocalPlanetOccultationSVGOptions ( options LocalPlanetOccultationSVGOptions ) LocalPlanetOccultationSVGOptions {
if options . Width <= 0 {
options . Width = localPlanetOccultationSVGDefaultWidth
}
if options . Height <= 0 {
options . Height = localPlanetOccultationSVGDefaultHeight
}
if options . Step <= 0 {
options . Step = localPlanetOccultationSVGDefaultStep
}
if options . Location == nil {
options . Location = time . FixedZone ( "UTC+8" , starOccultationSVGDefaultZone )
}
if strings . EqualFold ( options . Language , starOccultationSVGLanguageEnglish ) {
options . Language = starOccultationSVGLanguageEnglish
} else {
options . Language = starOccultationSVGLanguageChinese
}
return options
}
func renderLocalPlanetOccultationSVG (
info moon . PlanetOccultationInfo ,
diagram moon . PlanetOccultationDiagramResult ,
options LocalPlanetOccultationSVGOptions ,
) string {
title := localPlanetOccultationSVGTitle ( info , options )
headerLines := localPlanetOccultationSVGHeaderLines ( info , options )
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// 页眉字号 14/13，省略号按较大的 14 估算；行数上限只与画布高度有关，先按空页眉取上限。
headerLimit := localPlanetOccultationSVGLayoutFor ( options , 72 ). headerMaxLines
headerLines = svgchart . TruncateTextLines ( headerLines , float64 ( options . Width ) - 80 , 14 , headerLimit )
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headerBottom := 72.0 + float64 ( len ( headerLines )) * 19
layout := localPlanetOccultationSVGLayoutFor ( options , headerBottom )
events := localPlanetOccultationSVGEventFrames ( info , diagram . Frames , options . Language )
var b strings . Builder
fmt . Fprintf ( & b , `<svg xmlns="http://www.w3.org/2000/svg" width="%d" height="%d" viewBox="0 0 %d %d" role="img" aria-label="%s">` ,
options . Width , options . Height , options . Width , options . Height , html . EscapeString ( title ))
b . WriteString ( `<defs>` )
b . WriteString ( svgasset . MoonFaceSymbol ())
b . WriteString ( `<marker id="local-planet-occultation-arrow" viewBox="0 0 10 10" refX="8" refY="5" markerWidth="5" markerHeight="5" orient="auto-start-reverse"><path d="M 0 0 L 10 5 L 0 10 z" fill="#9b3f36"/></marker>` )
b . WriteString ( `</defs>` )
b . WriteString ( `<rect width="100%" height="100%" fill="#efefed"/>` )
fmt . Fprintf ( & b , `<rect x="22" y="18" width="%.3f" height="%.3f" fill="#ffffff" stroke="#c9c9c6" stroke-width="1.2"/>` , layout . width - 44 , layout . height - 36 )
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titleSize := starOccultationTitleFontSize ( title , layout . width )
titleText := title
if options . Title != "" {
titleText = svgchart . EllipsizeText ( title , layout . width - 80 , float64 ( titleSize ))
}
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fmt . Fprintf ( & b , `<text x="%.3f" y="44" fill="#111111" font-family="Georgia, 'Times New Roman', serif" font-size="%d" font-weight="700" text-anchor="middle">%s</text>` ,
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layout . width / 2 , titleSize , html . EscapeString ( titleText ))
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fmt . Fprintf ( & b , `<line x1="%.3f" y1="57" x2="%.3f" y2="57" stroke="#555" stroke-width="1"/>` , layout . width / 2 - 78 , layout . width / 2 + 78 )
for index , line := range headerLines {
fontSize , fill := 13 , "#3b4143"
if index == 0 {
fontSize , fill = 14 , "#222222"
}
fmt . Fprintf ( & b , `<text x="%.3f" y="%.3f" fill="%s" font-family="Georgia, 'Times New Roman', serif" font-size="%d" text-anchor="middle">%s</text>` ,
layout . width / 2 , 82 + float64 ( index ) * 19 , fill , fontSize , html . EscapeString ( line ))
}
writeLocalPlanetOccultationOverview ( & b , diagram , events , layout , options )
writeLocalPlanetOccultationContacts ( & b , events , layout , options )
writeLocalPlanetOccultationStages ( & b , events , layout , options )
writeLocalPlanetOccultationFooter ( & b , info , layout , options )
b . WriteString ( `</svg>` )
return b . String ()
}
func localPlanetOccultationSVGLayoutFor (
options LocalPlanetOccultationSVGOptions ,
headerBottom float64 ,
) localStarOccultationSVGLayout {
width := float64 ( options . Width )
height := float64 ( options . Height )
margin := math . Max ( 34 , math . Min ( 44 , width * 0.045 ))
gap := math . Max ( 18 , math . Min ( 24 , width * 0.025 ))
panelWidth := math . Max ( 210 , math . Min ( 258 , width * 0.25 ))
overviewLeft := margin
overviewRight := width - margin - panelWidth - gap
footerSpace := 88.0
stageHeight := math . Max ( 156 , math . Min ( 190 , height * 0.25 ))
stageBottom := height - footerSpace
stageTop := stageBottom - stageHeight
overviewTop := headerBottom + 26
overviewBottom := stageTop - 20
return localStarOccultationSVGLayout {
width : width ,
height : height ,
margin : margin ,
overviewLeft : overviewLeft ,
overviewRight : overviewRight ,
overviewTop : overviewTop ,
overviewBottom : overviewBottom ,
panelX : overviewRight + gap ,
panelWidth : panelWidth ,
stageTop : stageTop ,
stageBottom : stageBottom ,
footerY : height - 62 ,
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headerMaxLines : localOccultationHeaderLineLimit ( height , footerSpace , stageHeight ),
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}
}
func writeLocalPlanetOccultationOverview (
b * strings . Builder ,
diagram moon . PlanetOccultationDiagramResult ,
events [] localPlanetOccultationEventFrame ,
layout localStarOccultationSVGLayout ,
options LocalPlanetOccultationSVGOptions ,
) {
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overviewTitle := occultationTitleText ( localPlanetOccultationSVGOverviewTitle ( options ), options . OverviewTitle != "" ,
layout . panelX - layout . overviewLeft - 12 , 14 )
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fmt . Fprintf ( b , `<text x="%.3f" y="%.3f" fill="#161a1b" font-family="Georgia, 'Times New Roman', serif" font-size="14" font-weight="700">%s</text>` ,
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layout . overviewLeft , layout . overviewTop - 10 , html . EscapeString ( overviewTitle ))
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cx := ( layout . overviewLeft + layout . overviewRight ) / 2
cy := ( layout . overviewTop + layout . overviewBottom ) / 2 + 4
extent := localPlanetOccultationSVGExtent ( diagram . Frames )
availableWidth := layout . overviewRight - layout . overviewLeft - 74
availableHeight := layout . overviewBottom - layout . overviewTop - 50
scale := math . Min ( availableWidth / ( 2 * extent ), availableHeight / ( 2 * extent ))
if ! starOccultationFinite ( scale ) || scale <= 0 {
scale = 1
}
mapX := func ( value float64 ) float64 { return cx - value * scale }
mapY := func ( value float64 ) float64 { return cy - value * scale }
moonRadius := localPlanetOccultationSVGMaximumMoonRadius ( diagram . Frames ) * scale
writeLocalStarOccultationAxes ( b , cx , cy , moonRadius , options . Language )
writeLocalPlanetOccultationLunarPath ( b , diagram . Frames , mapX , mapY , extent , options . Language )
writeLocalPlanetOccultationTrack ( b , diagram . Frames , mapX , mapY )
for _ , event := range events {
writeLocalPlanetOccultationDisk ( b ,
mapX ( event . frame . PlanetXArcsec ), mapY ( event . frame . PlanetYArcsec ),
event . frame . PlanetRadiusArcsec * scale , false , "overview-planet-disk" , event . label ,
)
}
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writeLocalOccultationMoon ( b , cx , cy , moonRadius , "overview-moon" ,
localOccultationMoonAppearanceAt ( diagram . Occultation . Greatest , diagram . Occultation . Observer ),
"local-planet-occultation-moon-overview" )
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for _ , event := range events {
x := mapX ( event . frame . PlanetXArcsec )
y := mapY ( event . frame . PlanetYArcsec )
if event . hidden {
writeLocalPlanetOccultationDisk ( b , x , y , event . frame . PlanetRadiusArcsec * scale , true , "overview-planet-outline" , event . label )
}
if event . label != "C2" && event . label != "C3" {
writeLocalPlanetOccultationOverviewLabel ( b , event , x , y , cx , cy )
}
}
}
func localPlanetOccultationSVGExtent ( frames [] moon . PlanetOccultationDiagramFrame ) float64 {
extent := 1.0
for _ , frame := range frames {
extent = math . Max ( extent , frame . MoonRadiusArcsec )
extent = math . Max ( extent , math . Abs ( frame . PlanetXArcsec ) + frame . PlanetRadiusArcsec )
extent = math . Max ( extent , math . Abs ( frame . PlanetYArcsec ) + frame . PlanetRadiusArcsec )
}
return extent * 1.28
}
func localPlanetOccultationSVGMaximumMoonRadius ( frames [] moon . PlanetOccultationDiagramFrame ) float64 {
radius := 1.0
for _ , frame := range frames {
radius = math . Max ( radius , frame . MoonRadiusArcsec )
}
return radius
}
func writeLocalPlanetOccultationTrack (
b * strings . Builder ,
frames [] moon . PlanetOccultationDiagramFrame ,
mapX , mapY func ( float64 ) float64 ,
) {
if len ( frames ) < 2 {
return
}
var path strings . Builder
for index , frame := range frames {
command := "L"
if index == 0 {
command = "M"
}
fmt . Fprintf ( & path , "%s %.3f %.3f " , command , mapX ( frame . PlanetXArcsec ), mapY ( frame . PlanetYArcsec ))
}
fmt . Fprintf ( b , `<path class="local-planet-track" d="%s" fill="none" stroke="#9b3f36" stroke-width="1.7" stroke-dasharray="5 4" opacity="0.82" marker-end="url(#local-planet-occultation-arrow)"/>` , strings . TrimSpace ( path . String ()))
}
func writeLocalPlanetOccultationLunarPath (
b * strings . Builder ,
frames [] moon . PlanetOccultationDiagramFrame ,
mapX , mapY func ( float64 ) float64 ,
extent float64 ,
language string ,
) {
unitX , unitY , ok := localPlanetOccultationSVGLunarPathDirection ( frames )
if ! ok {
return
}
lineExtent := extent * 0.92
startX := mapX ( - unitX * lineExtent )
startY := mapY ( - unitY * lineExtent )
endX := mapX ( unitX * lineExtent )
endY := mapY ( unitY * lineExtent )
if ! starOccultationFinite ( startX ) || ! starOccultationFinite ( startY ) ||
! starOccultationFinite ( endX ) || ! starOccultationFinite ( endY ) {
return
}
fmt . Fprintf ( b , `<line class="lunar-path-line" x1="%.3f" y1="%.3f" x2="%.3f" y2="%.3f" stroke="#506975" stroke-width="1.1" stroke-dasharray="7 4" opacity="0.86"/>` ,
startX , startY , endX , endY )
labelX , labelY := startX , startY
if endX < startX {
labelX , labelY = endX , endY
}
fmt . Fprintf ( b , `<text class="lunar-path-label" x="%.3f" y="%.3f" fill="#405966" stroke="#ffffff" stroke-width="3" paint-order="stroke" font-family="Georgia, 'Times New Roman', serif" font-size="12" text-anchor="end">%s</text>` ,
labelX - 6 , labelY - 6 , html . EscapeString ( localStarOccultationSVGLunarPathLabel ( language )))
}
func localPlanetOccultationSVGLunarPathDirection ( frames [] moon . PlanetOccultationDiagramFrame ) ( float64 , float64 , bool ) {
if len ( frames ) < 2 {
return 0 , 0 , false
}
greatest := - 1
for index , frame := range frames {
if localPlanetOccultationSVGFrameHasLabel ( frame , "Greatest" ) {
greatest = index
break
}
}
left , right := 0 , len ( frames ) - 1
if greatest > 0 && greatest + 1 < len ( frames ) {
left , right = greatest - 1 , greatest + 1
} else if greatest == 0 {
left , right = 0 , 1
} else if greatest == len ( frames ) - 1 {
left , right = len ( frames ) - 2 , len ( frames ) - 1
}
dx := frames [ right ]. PlanetXArcsec - frames [ left ]. PlanetXArcsec
dy := frames [ right ]. PlanetYArcsec - frames [ left ]. PlanetYArcsec
length := math . Hypot ( dx , dy )
if ! starOccultationFinite ( length ) || length == 0 {
return 0 , 0 , false
}
return dx / length , dy / length , true
}
func writeLocalPlanetOccultationDisk (
b * strings . Builder ,
x , y , radius float64 ,
hidden bool ,
class , label string ,
) {
fill , stroke , dash := "#d6ad69" , "#704b2d" , ""
if hidden {
fill , stroke , dash = "none" , "#7d3430" , ` stroke-dasharray="2 2"`
}
fmt . Fprintf ( b , `<circle class="%s" data-label="%s" cx="%.3f" cy="%.3f" r="%.3f" fill="%s" stroke="%s" stroke-width="1.2"%s/>` ,
html . EscapeString ( class ), html . EscapeString ( label ), x , y , math . Max ( radius , 0.15 ), fill , stroke , dash )
}
func writeLocalPlanetOccultationOverviewLabel (
b * strings . Builder ,
event localPlanetOccultationEventFrame ,
x , y , cx , cy float64 ,
) {
dx , dy , anchor := 8.0 , - 9.0 , "start"
if x > cx {
dx , anchor = - 8 , "end"
}
if y < cy - 20 {
dy = 15
}
fmt . Fprintf ( b , `<text x="%.3f" y="%.3f" fill="#792d28" stroke="#ffffff" stroke-width="3" paint-order="stroke" font-family="Arial, sans-serif" font-size="11" font-weight="700" text-anchor="%s">%s</text>` ,
x + dx , y + dy , anchor , html . EscapeString ( event . name ))
}
func writeLocalPlanetOccultationContacts (
b * strings . Builder ,
events [] localPlanetOccultationEventFrame ,
layout localStarOccultationSVGLayout ,
options LocalPlanetOccultationSVGOptions ,
) {
fmt . Fprintf ( b , `<line x1="%.3f" y1="%.3f" x2="%.3f" y2="%.3f" stroke="#d0d3d1" stroke-width="1"/>` ,
layout . panelX - 12 , layout . overviewTop - 12 , layout . panelX - 12 , layout . overviewBottom )
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contactsTitle := occultationTitleText ( localPlanetOccultationSVGContactsTitle ( options ), options . ContactsTitle != "" ,
layout . width - layout . panelX - layout . margin , 14 )
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fmt . Fprintf ( b , `<text x="%.3f" y="%.3f" fill="#161a1b" font-family="Georgia, 'Times New Roman', serif" font-size="14" font-weight="700">%s</text>` ,
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layout . panelX , layout . overviewTop - 10 , html . EscapeString ( contactsTitle ))
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available := layout . overviewBottom - layout . overviewTop - 10
rowHeight := math . Min ( 66 , available / math . Max ( 1 , float64 ( len ( events ))))
for index , event := range events {
y := layout . overviewTop + 16 + float64 ( index ) * rowHeight
if index > 0 {
fmt . Fprintf ( b , `<line x1="%.3f" y1="%.3f" x2="%.3f" y2="%.3f" stroke="#e0e1df" stroke-width="0.8"/>` ,
layout . panelX , y - 12 , layout . panelX + layout . panelWidth , y - 12 )
}
fmt . Fprintf ( b , `<text x="%.3f" y="%.3f" fill="#1c2528" font-family="Arial, sans-serif" font-size="11" font-weight="700">%s</text>` ,
layout . panelX , y , html . EscapeString ( event . name ))
fmt . Fprintf ( b , `<text x="%.3f" y="%.3f" fill="#1c2528" font-family="Arial, sans-serif" font-size="10" text-anchor="end">%s</text>` ,
layout . panelX + layout . panelWidth , y , html . EscapeString ( event . time . In ( options . Location ). Format ( "15:04:05.0" )))
fmt . Fprintf ( b , `<text x="%.3f" y="%.3f" fill="#536063" font-family="Arial, sans-serif" font-size="9.5">PA %.1f° | %s %.1f° | %s %.1f°</text>` ,
layout . panelX , y + 16 , event . frame . PositionAngleDeg ,
localStarOccultationSVGAltitudeLabel ( options . Language ), event . frame . MoonAltitudeDeg ,
localStarOccultationSVGAzimuthLabel ( options . Language ), event . frame . MoonAzimuthDeg )
fmt . Fprintf ( b , `<text x="%.3f" y="%.3f" fill="#6b7577" font-family="Arial, sans-serif" font-size="9.5">r %.2f″ | %s</text>` ,
layout . panelX , y + 31 , event . frame . PlanetRadiusArcsec ,
html . EscapeString ( localStarOccultationSVGVisibilityText ( event . frame . MoonAltitudeDeg >= 0 , options . Language )))
}
}
func writeLocalPlanetOccultationStages (
b * strings . Builder ,
events [] localPlanetOccultationEventFrame ,
layout localStarOccultationSVGLayout ,
options LocalPlanetOccultationSVGOptions ,
) {
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phaseTitle := occultationTitleText ( localPlanetOccultationSVGPhasePanelsTitle ( options ), options . PhasePanelsTitle != "" ,
layout . width - 2 * layout . margin , 14 )
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fmt . Fprintf ( b , `<text x="%.3f" y="%.3f" fill="#161a1b" font-family="Georgia, 'Times New Roman', serif" font-size="14" font-weight="700">%s</text>` ,
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layout . margin , layout . stageTop + 13 , html . EscapeString ( phaseTitle ))
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if len ( events ) == 0 {
return
}
usableWidth := layout . width - 2 * layout . margin
columnWidth := usableWidth / float64 ( len ( events ))
maxMoonRadius := localPlanetOccultationSVGMaximumMoonRadiusFromEvents ( events )
radius := math . Min ( 43 , math . Max ( 31 , ( layout . stageBottom - layout . stageTop - 59 ) / 2 ))
scale := radius / maxMoonRadius
cy := layout . stageTop + 35 + radius
for index , event := range events {
cx := layout . margin + columnWidth * ( float64 ( index ) + 0.5 )
trueRadius := event . frame . PlanetRadiusArcsec * scale
displayRadius := math . Max ( trueRadius , 5.5 )
magnification := displayRadius / math . Max ( trueRadius , 1e-9 )
x , y := localPlanetOccultationSVGStageCenter ( event , cx , cy , radius , displayRadius , scale )
fmt . Fprintf ( b , `<circle class="stage-planet-disk" data-label="%s" data-true-radius="%.3f" data-magnification="%.3f" cx="%.3f" cy="%.3f" r="%.3f" fill="#d6ad69" stroke="#704b2d" stroke-width="1.1"/>` ,
html . EscapeString ( event . label ), trueRadius , magnification , x , y , displayRadius )
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writeLocalOccultationMoon ( b , cx , cy , event . frame . MoonRadiusArcsec * scale , "stage-moon" ,
event . appearance , fmt . Sprintf ( "local-planet-occultation-moon-stage-%d" , index ))
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if event . hidden {
fmt . Fprintf ( b , `<circle class="stage-planet-hidden-outline" cx="%.3f" cy="%.3f" r="%.3f" fill="none" stroke="#7d3430" stroke-width="1.1" stroke-dasharray="2 2"/>` ,
x , y , displayRadius )
}
fmt . Fprintf ( b , `<text x="%.3f" y="%.3f" fill="#1c2528" font-family="Arial, sans-serif" font-size="10.5" font-weight="700" text-anchor="middle">%s</text>` ,
cx , cy + radius + 18 , html . EscapeString ( event . name ))
fmt . Fprintf ( b , `<text x="%.3f" y="%.3f" fill="#667174" font-family="Arial, sans-serif" font-size="9.5" text-anchor="middle">%s</text>` ,
cx , cy + radius + 32 , html . EscapeString ( event . time . In ( options . Location ). Format ( "15:04:05.0" )))
}
}
// 阶段面板会放大较小的行星盘面以便观察，并在接触时同步移动显示中心，使 C1/C4 仍外切、C2/C3 仍内切。这只影响展示；事件时刻和总览使用未修改的站心几何。
// The stage panels enlarge small planet disks for visibility and move the display center by the same amount at contacts so C1/C4 remain externally tangent and C2/C3 remain internally tangent. This only affects presentation; event times and the overview use the unmodified topocentric geometry.
func localPlanetOccultationSVGStageCenter (
event localPlanetOccultationEventFrame ,
cx , cy , moonRadius , displayRadius , scale float64 ,
) ( float64 , float64 ) {
distance := event . frame . SeparationArcsec * scale
switch event . label {
case "C1" , "C4" :
distance = moonRadius + displayRadius
case "C2" , "C3" :
distance = math . Max ( 0 , moonRadius - displayRadius )
}
angle := event . frame . PositionAngleDeg * math . Pi / 180
return cx - distance * math . Sin ( angle ), cy - distance * math . Cos ( angle )
}
func localPlanetOccultationSVGMaximumMoonRadiusFromEvents ( events [] localPlanetOccultationEventFrame ) float64 {
radius := 1.0
for _ , event := range events {
radius = math . Max ( radius , event . frame . MoonRadiusArcsec )
}
return radius
}
func writeLocalPlanetOccultationFooter (
b * strings . Builder ,
info moon . PlanetOccultationInfo ,
layout localStarOccultationSVGLayout ,
options LocalPlanetOccultationSVGOptions ,
) {
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directionLines , footerLines := localOccultationFooterLines (
localPlanetOccultationSVGDirectionText ( options ), options . DirectionText != "" ,
localPlanetOccultationSVGFooterNote ( info , options ), options . FooterNote != "" ,
layout . footerY , layout . width , layout . height )
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for index , line := range directionLines {
fmt . Fprintf ( b , `<text x="%.3f" y="%.3f" fill="#4f595b" font-family="Georgia, 'Times New Roman', serif" font-size="10">%s</text>` ,
layout . margin , layout . footerY + float64 ( index ) * 14 - 8 , html . EscapeString ( line ))
}
for index , line := range footerLines {
fmt . Fprintf ( b , `<text x="%.3f" y="%.3f" fill="#747c7d" font-family="Georgia, 'Times New Roman', serif" font-size="9">%s</text>` ,
layout . margin , layout . footerY + float64 ( len ( directionLines )) * 14 + float64 ( index ) * 12 - 6 , html . EscapeString ( line ))
}
}
func localPlanetOccultationSVGEventFrames (
info moon . PlanetOccultationInfo ,
frames [] moon . PlanetOccultationDiagramFrame ,
language string ,
) [] localPlanetOccultationEventFrame {
times := map [ string ] time . Time {
"C1" : info . ExternalImmersion ,
"C2" : info . InternalImmersion ,
"Greatest" : info . Greatest ,
"C3" : info . InternalEmersion ,
"C4" : info . ExternalEmersion ,
}
labels := [] string { "C1" , "Greatest" , "C4" }
if info . HasInternalContacts {
labels = [] string { "C1" , "C2" , "Greatest" , "C3" , "C4" }
}
result := make ([] localPlanetOccultationEventFrame , 0 , len ( labels ))
for _ , label := range labels {
for _ , frame := range frames {
if localPlanetOccultationSVGFrameHasLabel ( frame , label ) {
hidden := frame . FullyOcculted || info . Type == moon . OccultationTotal &&
( label == "C2" || label == "Greatest" || label == "C3" )
result = append ( result , localPlanetOccultationEventFrame {
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label : label ,
name : localPlanetOccultationSVGEventName ( label , language ),
time : times [ label ],
hidden : hidden ,
frame : frame ,
appearance : localOccultationMoonAppearanceAt ( times [ label ], info . Observer ),
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})
break
}
}
}
return result
}
func localPlanetOccultationSVGFrameHasLabel ( frame moon . PlanetOccultationDiagramFrame , label string ) bool {
if frame . Label == label {
return true
}
for _ , current := range frame . Labels {
if current == label {
return true
}
}
return false
}
func localPlanetOccultationSVGHeaderLines (
info moon . PlanetOccultationInfo ,
options LocalPlanetOccultationSVGOptions ,
) [] string {
lines := make ([] string , 0 , 4 )
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for _ , item := range [] struct {
value string
custom bool
}{
{ localPlanetOccultationSVGSummaryText ( info , options ), options . SummaryText != "" },
{ localPlanetOccultationSVGGreatestText ( info , options ), options . GreatestText != "" },
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} {
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lines = append ( lines , occultationWrappedTextLines ( item . value , item . custom , float64 ( options . Width ) - 80 , 13 ) ... )
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}
return lines
}
func localPlanetOccultationSVGTargetName (
info moon . PlanetOccultationInfo ,
language string ,
) string {
target := strings . TrimSpace ( info . TargetID )
if language == starOccultationSVGLanguageChinese && ( target == "" || target == info . Planet . String ()) {
return planetOccultationChineseName ( info . Planet )
}
if target != "" {
return target
}
if language == starOccultationSVGLanguageEnglish {
return info . Planet . String ()
}
return "行星"
}
func localPlanetOccultationSVGTitle (
info moon . PlanetOccultationInfo ,
options LocalPlanetOccultationSVGOptions ,
) string {
if options . Title != "" {
return options . Title
}
date := info . Greatest . In ( options . Location ). Format ( "2006-01-02" )
target := localPlanetOccultationSVGTargetName ( info , options . Language )
if options . Language == starOccultationSVGLanguageEnglish {
return fmt . Sprintf ( "%s Local Lunar Occultation of %s" , date , target )
}
return fmt . Sprintf ( "%s 指定地点月掩%s" , date , target )
}
func localPlanetOccultationSVGSummaryText (
info moon . PlanetOccultationInfo ,
options LocalPlanetOccultationSVGOptions ,
) string {
if options . SummaryText != "" {
return options . SummaryText
}
coordinates := starOccultationFormatCoordinates ( info . Observer . Longitude , info . Observer . Latitude )
duration := localStarOccultationSVGFormatDuration ( info . ExternalEmersion . Sub ( info . ExternalImmersion ), options . Language )
if options . Language == starOccultationSVGLanguageEnglish {
return fmt . Sprintf ( "Site %s | elevation %.0f m | %s | C1-C4 duration %s" , coordinates , info . Observer . Height ,
localPlanetOccultationSVGTypeName ( info . Type , options . Language ), duration )
}
return fmt . Sprintf ( "观测点 %s | 海拔 %.0f 米 | %s | C1-C4 历时 %s" , coordinates , info . Observer . Height ,
localPlanetOccultationSVGTypeName ( info . Type , options . Language ), duration )
}
func localPlanetOccultationSVGGreatestText (
info moon . PlanetOccultationInfo ,
options LocalPlanetOccultationSVGOptions ,
) string {
if options . GreatestText != "" {
return options . GreatestText
}
value := info . Greatest . In ( options . Location )
zone := starOccultationLocationLabel ( value , options . Location )
if options . Language == starOccultationSVGLanguageEnglish {
return fmt . Sprintf ( "Greatest %s %s | separation %.2f arcsec | radii Moon %.2f / planet %.2f arcsec | Moon altitude %+.1f°" ,
value . Format ( "2006-01-02 15:04:05.0" ), zone , info . MinimumSeparationArcsec ,
info . MoonSemidiameterArcsec , info . PlanetSemidiameterArcsec , info . MoonAltitudeAtGreatest )
}
return fmt . Sprintf ( "掩甚 %s %s | 中心角距 %.2f 角秒 | 视半径 月 %.2f / 行星 %.2f 角秒 | 月球高度 %+.1f°" ,
value . Format ( "2006-01-02 15:04:05.0" ), zone , info . MinimumSeparationArcsec ,
info . MoonSemidiameterArcsec , info . PlanetSemidiameterArcsec , info . MoonAltitudeAtGreatest )
}
func localPlanetOccultationSVGOverviewTitle ( options LocalPlanetOccultationSVGOptions ) string {
if options . OverviewTitle != "" {
return options . OverviewTitle
}
if options . Language == starOccultationSVGLanguageEnglish {
return "Topocentric planet track (true disk scale)"
}
return "站心行星轨迹（圆盘真实比例）"
}
func localPlanetOccultationSVGPhasePanelsTitle ( options LocalPlanetOccultationSVGOptions ) string {
if options . PhasePanelsTitle != "" {
return options . PhasePanelsTitle
}
if options . Language == starOccultationSVGLanguageEnglish {
return "C1-C4 contact stages (planet disk enlarged)"
}
return "C1-C4 接触阶段（行星圆盘放大示意）"
}
func localPlanetOccultationSVGContactsTitle ( options LocalPlanetOccultationSVGOptions ) string {
if options . ContactsTitle != "" {
return options . ContactsTitle
}
if options . Language == starOccultationSVGLanguageEnglish {
return "Local contacts"
}
return "本地接触时刻"
}
func localPlanetOccultationSVGDirectionText ( options LocalPlanetOccultationSVGOptions ) string {
if options . DirectionText != "" {
return options . DirectionText
}
if options . Language == starOccultationSVGLanguageEnglish {
return "Moon fixed at center; east is left and north is up. Blue-gray dashed: local lunar path. Red dashed: planet-center track."
}
return "月球固定在中心；图上左东右西，向上为北。灰蓝虚线为掩甚附近的站心白道，红色虚线为行星中心相对月心轨迹。"
}
func localPlanetOccultationSVGFooterNote (
info moon . PlanetOccultationInfo ,
options LocalPlanetOccultationSVGOptions ,
) string {
if options . FooterNote != "" {
return options . FooterNote
}
ringNote := ""
if info . Planet == moon . OccultationSaturn {
if options . Language == starOccultationSVGLanguageEnglish {
ringNote = " Saturn's rings are excluded from contact calculation and drawing."
} else {
ringNote = "土星环不参与接触计算，也不作为圆盘边界绘制。"
}
}
if options . Language == starOccultationSVGLanguageEnglish {
return "C1/C4 are external contacts; C2/C3 are internal contacts. Stage disks are enlarged for visibility; contact times use true topocentric radii." + ringNote
}
return "C1/C4 为外切，C2/C3 为内切。阶段图中的行星圆盘为可见性放大，接触时刻按真实站心视半径求解。" + ringNote
}
func localPlanetOccultationSVGEventName ( label , language string ) string {
if language == starOccultationSVGLanguageEnglish {
switch label {
case "C1" :
return "C1 external ingress"
case "C2" :
return "C2 internal ingress"
case "Greatest" :
return "Greatest"
case "C3" :
return "C3 internal egress"
case "C4" :
return "C4 external egress"
}
}
switch label {
case "C1" :
return "C1 外切始"
case "C2" :
return "C2 内切始"
case "Greatest" :
return "掩甚"
case "C3" :
return "C3 内切终"
case "C4" :
return "C4 外切终"
default :
return label
}
}
func localPlanetOccultationSVGTypeName ( eventType moon . OccultationType , language string ) string {
if language == starOccultationSVGLanguageEnglish {
switch eventType {
case moon . OccultationTotal :
return "total occultation"
case moon . OccultationPartial :
return "partial occultation"
default :
return "grazing occultation"
}
}
switch eventType {
case moon . OccultationTotal :
return "行星圆面全掩"
case moon . OccultationPartial :
return "行星圆面部分掩"
default :
return "行星圆面擦边"
}
}
