342 lines
14 KiB
Go
342 lines
14 KiB
Go
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package svg
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import (
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"fmt"
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"html"
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"math"
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"strings"
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"time"
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"b612.me/astro/basic"
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eclipsecore "b612.me/astro/eclipse"
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"b612.me/astro/internal/svgmap"
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)
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const (
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lunarEclipseMapDefaultWidth = 960
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lunarEclipseMapDefaultHeight = 640
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)
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// LunarEclipseMapSVGOptions 控制无国界全球可见性地图。
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// LunarEclipseMapSVGOptions controls a border-free global visibility map.
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type LunarEclipseMapSVGOptions struct {
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// Width 和 Height 是 SVG 画布尺寸；宽度小于 640 或高度小于 420 时使用 960x640 默认值。
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// Width and Height are SVG canvas dimensions in user units. Width values below 640 and height values below 420 use the 960x640 defaults.
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Width int
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Height int
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// Language 为 "en"（不区分大小写）时使用英文，否则使用中文。
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// Language uses English for "en" (case-insensitive) and Chinese otherwise.
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Language string
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// Location 控制显示的事件时刻；nil 使用 date.Location()。
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// Location controls displayed event times. Nil uses date.Location().
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Location *time.Location
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// Projection 选择地图投影；零值使用等经纬投影，不支持的值使渲染器返回 false。
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// Projection selects the map projection. The zero value selects the equirectangular projection; unsupported values make the renderer return false.
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Projection EclipseMapProjection
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// 空文本字段使用本地化的自动标签。
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// Empty text fields use localized automatic labels.
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Title string
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FooterNote string
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}
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// LunarEclipseMapSVG 使用默认月食模型绘制全球 P1-P4 可见区域。
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// LunarEclipseMapSVG renders the global P1-P4 visibility regions using the default lunar-eclipse model.
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func LunarEclipseMapSVG(date time.Time, options LunarEclipseMapSVGOptions) (string, bool) {
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return lunarEclipseMapSVG(date, options, eclipsecore.LunarEclipseOnDate)
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}
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// LunarEclipseMapSVGDanjon 使用 Danjon 模型绘制全球可见区域。
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// LunarEclipseMapSVGDanjon renders the global visibility regions with Danjon's model.
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func LunarEclipseMapSVGDanjon(date time.Time, options LunarEclipseMapSVGOptions) (string, bool) {
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return lunarEclipseMapSVG(date, options, eclipsecore.LunarEclipseOnDateDanjon)
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}
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// LunarEclipseMapSVGChauvenet 使用 Chauvenet 模型绘制全球可见区域。
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// LunarEclipseMapSVGChauvenet renders the global visibility regions with Chauvenet's model.
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func LunarEclipseMapSVGChauvenet(date time.Time, options LunarEclipseMapSVGOptions) (string, bool) {
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return lunarEclipseMapSVG(date, options, eclipsecore.LunarEclipseOnDateChauvenet)
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}
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func lunarEclipseMapSVG(
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date time.Time,
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options LunarEclipseMapSVGOptions,
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calculator func(time.Time) (eclipsecore.LunarEclipseInfo, bool),
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) (string, bool) {
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if !validEclipseMapProjection(options.Projection) {
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return "", false
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}
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info, ok := calculator(date)
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if !ok || info.PenumbralStart.IsZero() || info.PenumbralEnd.IsZero() {
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return "", false
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}
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options = normalizeLunarEclipseMapSVGOptions(date, options)
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projection := internalEclipseMapProjection(options.Projection)
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if projection == "" {
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projection = svgmap.ProjectionEquirectangular
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}
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return renderLunarEclipseMapSVG(info, options, projection), true
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}
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func normalizeLunarEclipseMapSVGOptions(date time.Time, options LunarEclipseMapSVGOptions) LunarEclipseMapSVGOptions {
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if options.Width < 640 {
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options.Width = lunarEclipseMapDefaultWidth
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}
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if options.Height < 420 {
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options.Height = lunarEclipseMapDefaultHeight
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}
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if strings.EqualFold(options.Language, "en") {
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options.Language = "en"
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} else {
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options.Language = "zh"
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}
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if options.Location == nil {
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options.Location = date.Location()
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}
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return options
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}
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func renderLunarEclipseMapSVG(
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info eclipsecore.LunarEclipseInfo,
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options LunarEclipseMapSVGOptions,
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projection svgmap.Projection,
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) string {
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frame := eclipseMapFrame(options.Width, options.Height, projection, 142, 92)
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startPath, startBoundary := lunarEclipseVisibilityPath(info.PenumbralStart, frame)
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endPath, endBoundary := lunarEclipseVisibilityPath(info.PenumbralEnd, frame)
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title := options.Title
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if title == "" {
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date := info.Maximum.In(options.Location).Format("2006-01-02")
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if options.Language == "en" {
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title = fmt.Sprintf("%s %s Global Visibility", date, lunarEclipseSVGTypeName(info.Type, "en"))
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} else {
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title = fmt.Sprintf("%s %s全球可见图", date, lunarEclipseSVGTypeName(info.Type, "zh"))
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}
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}
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var builder strings.Builder
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fmt.Fprintf(&builder, `<svg xmlns="http://www.w3.org/2000/svg" width="%d" height="%d" viewBox="0 0 %d %d" role="img" aria-label="%s">`,
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options.Width, options.Height, options.Width, options.Height, html.EscapeString(title))
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builder.WriteString(`<defs>`)
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builder.WriteString(frame.ClipDefinition("lunar-map-clip"))
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fmt.Fprintf(&builder, `<path id="lunar-visible-p1-shape" d="%s"/>`, startPath)
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fmt.Fprintf(&builder, `<path id="lunar-visible-p4-shape" d="%s"/>`, endPath)
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builder.WriteString(`<clipPath id="lunar-visible-p4"><use href="#lunar-visible-p4-shape"/></clipPath>`)
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writeLunarEclipseVisibilityMasks(&builder, frame)
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builder.WriteString(`</defs>`)
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builder.WriteString(`<rect width="100%" height="100%" fill="#efefed"/>`)
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fmt.Fprintf(&builder, `<rect x="22" y="18" width="%d" height="%d" fill="#ffffff" stroke="#c9c9c6" stroke-width="1.2"/>`,
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options.Width-44, options.Height-36)
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fmt.Fprintf(&builder, `<text x="%.3f" y="47" fill="#111111" font-family="Georgia, 'Times New Roman', serif" font-size="24" font-weight="700" text-anchor="middle">%s</text>`,
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float64(options.Width)/2, html.EscapeString(title))
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writeLunarEclipseMapSummary(&builder, info, options)
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frame.WriteOcean(&builder)
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frame.WriteGraticule(&builder, "lunar-map-clip")
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frame.WriteLand(&builder, "lunar-map-clip")
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fmt.Fprintf(&builder, `<g class="lunar-visibility-regions" clip-path="url(#lunar-map-clip)">`)
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writeLunarEclipseUnavailableRegion(&builder, frame)
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builder.WriteString(`<use class="visible-at-p1 moonset-region" mask="url(#lunar-not-p4-mask)" href="#lunar-visible-p1-shape" fill="#e2aa4b" fill-opacity="0.34"/>`)
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builder.WriteString(`<use class="visible-at-p4 moonrise-region" mask="url(#lunar-not-p1-mask)" href="#lunar-visible-p4-shape" fill="#4e9da0" fill-opacity="0.34"/>`)
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builder.WriteString(`<g clip-path="url(#lunar-visible-p4)"><use class="entire-eclipse-region" href="#lunar-visible-p1-shape" fill="#5e846d" fill-opacity="0.34"/></g>`)
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builder.WriteString(`</g>`)
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writeEclipseMapGeoLine(&builder, frame, startBoundary, "p1-horizon", "#a56c16", 1.2, "4 3", "lunar-map-clip")
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writeEclipseMapGeoLine(&builder, frame, endBoundary, "p4-horizon", "#197a82", 1.2, "4 3", "lunar-map-clip")
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frame.WriteFrame(&builder)
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writeLunarEclipseMapLegend(&builder, frame, options.Language)
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writeLunarEclipseMapFooter(&builder, frame, options, projection)
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builder.WriteString(`</svg>`)
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return builder.String()
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}
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func writeLunarEclipseVisibilityMasks(builder *strings.Builder, frame svgmap.Frame) {
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writeLunarEclipseVisibilityMask(builder, "lunar-not-visible-mask", frame,
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"lunar-visible-p1-shape", "lunar-visible-p4-shape")
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writeLunarEclipseVisibilityMask(builder, "lunar-not-p4-mask", frame, "lunar-visible-p4-shape")
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writeLunarEclipseVisibilityMask(builder, "lunar-not-p1-mask", frame, "lunar-visible-p1-shape")
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}
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func writeLunarEclipseVisibilityMask(
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builder *strings.Builder,
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id string,
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frame svgmap.Frame,
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excludedShapeIDs ...string,
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) {
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fmt.Fprintf(builder, `<mask id="%s" maskUnits="userSpaceOnUse" x="%.3f" y="%.3f" width="%.3f" height="%.3f">`,
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id, frame.X, frame.Y, frame.Width, frame.Height)
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fmt.Fprintf(builder, `<rect x="%.3f" y="%.3f" width="%.3f" height="%.3f" fill="#ffffff"/>`,
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frame.X, frame.Y, frame.Width, frame.Height)
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for _, shapeID := range excludedShapeIDs {
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fmt.Fprintf(builder, `<use href="#%s" fill="#000000"/>`, shapeID)
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}
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builder.WriteString(`</mask>`)
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}
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func eclipseMapFrame(width, height int, projection svgmap.Projection, top, bottom float64) svgmap.Frame {
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availableWidth := float64(width) - 90
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availableHeight := float64(height) - top - bottom
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mapWidth := math.Min(availableWidth, availableHeight*2)
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mapHeight := mapWidth / 2
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if projection != svgmap.ProjectionEquirectangular {
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mapWidth = math.Min(availableWidth, availableHeight)
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mapHeight = mapWidth
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}
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return svgmap.Frame{
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X: (float64(width) - mapWidth) / 2,
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Y: top,
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Width: mapWidth,
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Height: mapHeight,
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Projection: projection,
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}
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}
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func lunarEclipseVisibilityPath(value time.Time, frame svgmap.Frame) (string, []svgmap.GeoPoint) {
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center := lunarEclipseSubpoint(value)
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boundary := svgmap.SphericalCircle(center, 90, 360)
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path := lunarEclipseVisibilityPathForCenter(center, frame)
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closedBoundary := append(append([]svgmap.GeoPoint(nil), boundary...), boundary[0])
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return path, closedBoundary
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}
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func lunarEclipseVisibilityPathForCenter(center svgmap.GeoPoint, frame svgmap.Frame) string {
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var builder strings.Builder
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for _, polygon := range svgmap.VisibleHemispherePolygons(center, frame.Projection, 360) {
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appendEclipseMapPolygonPath(&builder, frame, polygon)
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}
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return builder.String()
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}
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func lunarEclipseVisibilityPolygons(
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center svgmap.GeoPoint,
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projection svgmap.Projection,
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samples int,
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) [][]svgmap.GeoPoint {
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return svgmap.VisibleHemispherePolygons(center, projection, samples)
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}
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func lunarEclipseSubpoint(value time.Time) svgmap.GeoPoint {
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ttJDE := timeToTTJDE(value)
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ra, dec := basic.HMoonTrueRaDec(ttJDE)
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utJDE := basic.TD2UT(ttJDE, false)
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longitude := normalizeDegree180(ra - basic.ApparentSiderealTime(utJDE)*15)
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return svgmap.GeoPoint{Longitude: longitude, Latitude: dec}
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}
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func appendEclipseMapPolygonPath(builder *strings.Builder, frame svgmap.Frame, points []svgmap.GeoPoint) {
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if len(points) < 3 {
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return
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}
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for index, point := range points {
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x, y, ok := frame.Project(point.Longitude, point.Latitude)
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if !ok {
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continue
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}
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command := "L"
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if index == 0 {
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command = "M"
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}
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fmt.Fprintf(builder, `%s %.3f %.3f `, command, x, y)
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}
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builder.WriteString(`Z `)
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}
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func writeEclipseMapGeoLine(
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builder *strings.Builder,
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frame svgmap.Frame,
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points []svgmap.GeoPoint,
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className, color string,
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strokeWidth float64,
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dash, clipID string,
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) {
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for _, segment := range svgmap.PolylineSegments(points, frame.Projection) {
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if len(segment) < 2 {
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continue
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}
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fmt.Fprintf(builder, `<path class="%s" d="`, className)
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for index, point := range segment {
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x, y, ok := frame.Project(point.Longitude, point.Latitude)
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if !ok {
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continue
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}
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command := "L"
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if index == 0 {
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command = "M"
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}
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fmt.Fprintf(builder, `%s %.3f %.3f `, command, x, y)
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}
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fmt.Fprintf(builder, `" clip-path="url(#%s)" fill="none" stroke="%s" stroke-width="%.2f" stroke-dasharray="%s" stroke-linecap="round"/>`,
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clipID, color, strokeWidth, dash)
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}
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}
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func writeLunarEclipseUnavailableRegion(builder *strings.Builder, frame svgmap.Frame) {
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if frame.IsPolar() {
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fmt.Fprintf(builder, `<circle class="eclipse-unavailable-region" mask="url(#lunar-not-visible-mask)" cx="%.3f" cy="%.3f" r="%.3f" fill="#747b7d" fill-opacity="0.34"/>`,
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frame.X+frame.Width/2, frame.Y+frame.Height/2, frame.Width/2)
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return
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}
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fmt.Fprintf(builder, `<rect class="eclipse-unavailable-region" mask="url(#lunar-not-visible-mask)" x="%.3f" y="%.3f" width="%.3f" height="%.3f" fill="#747b7d" fill-opacity="0.34"/>`,
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frame.X, frame.Y, frame.Width, frame.Height)
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}
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func writeLunarEclipseMapSummary(builder *strings.Builder, info eclipsecore.LunarEclipseInfo, options LunarEclipseMapSVGOptions) {
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start := info.PenumbralStart.In(options.Location)
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maximum := info.Maximum.In(options.Location)
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end := info.PenumbralEnd.In(options.Location)
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zone, _ := maximum.Zone()
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if zone == "" {
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zone = "UTC"
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}
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text := fmt.Sprintf("P1 %s | 食甚 %s | P4 %s (%s) | 半影食分 %.3f | 本影食分 %.3f",
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start.Format("15:04:05"), maximum.Format("15:04:05"), end.Format("15:04:05"), zone,
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info.PenumbralMagnitude, info.UmbralMagnitude)
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if options.Language == "en" {
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text = fmt.Sprintf("P1 %s | Greatest %s | P4 %s (%s) | penumbral magnitude %.3f | umbral magnitude %.3f",
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start.Format("15:04:05"), maximum.Format("15:04:05"), end.Format("15:04:05"), zone,
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info.PenumbralMagnitude, info.UmbralMagnitude)
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}
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fmt.Fprintf(builder, `<text x="%.3f" y="82" fill="#293235" font-family="Arial, sans-serif" font-size="13" text-anchor="middle">%s</text>`,
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float64(options.Width)/2, html.EscapeString(text))
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}
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func writeLunarEclipseMapLegend(builder *strings.Builder, frame svgmap.Frame, language string) {
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labels := []string{"全程可见", "带食月出", "带食月落", "不可见"}
|
||
|
|
colors := []string{"#5e846d", "#4e9da0", "#e2aa4b", "#747b7d"}
|
||
|
|
if language == "en" {
|
||
|
|
labels = []string{"Entire eclipse", "Moonrise during eclipse", "Moonset during eclipse", "Not visible"}
|
||
|
|
}
|
||
|
|
y := frame.Y + frame.Height + 31
|
||
|
|
itemWidth := frame.Width / 4
|
||
|
|
for index, label := range labels {
|
||
|
|
x := frame.X + float64(index)*itemWidth
|
||
|
|
fmt.Fprintf(builder, `<rect x="%.3f" y="%.3f" width="18" height="9" fill="%s" fill-opacity="0.78"/>`, x, y-8, colors[index])
|
||
|
|
fmt.Fprintf(builder, `<text x="%.3f" y="%.3f" fill="#465053" font-family="Arial, sans-serif" font-size="10">%s</text>`,
|
||
|
|
x+24, y, html.EscapeString(label))
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
func writeLunarEclipseMapFooter(
|
||
|
|
builder *strings.Builder,
|
||
|
|
frame svgmap.Frame,
|
||
|
|
options LunarEclipseMapSVGOptions,
|
||
|
|
projection svgmap.Projection,
|
||
|
|
) {
|
||
|
|
text := options.FooterNote
|
||
|
|
if text == "" {
|
||
|
|
if options.Language == "en" {
|
||
|
|
text = eclipseMapProjectionLabel(projection, "en") + "; P1/P4 Moon-visible hemispheres; Natural Earth 1:50m physical land, no administrative boundaries."
|
||
|
|
} else {
|
||
|
|
text = eclipseMapProjectionLabel(projection, "zh") + "；按 P1/P4 月球可见半球分区；Natural Earth 1:50m 物理陆地底图，不含行政边界。"
|
||
|
|
}
|
||
|
|
}
|
||
|
|
fmt.Fprintf(builder, `<text x="%.3f" y="%.3f" fill="#596164" font-family="Georgia, 'Times New Roman', serif" font-size="11">%s</text>`,
|
||
|
|
frame.X, float64(options.Height)-38, html.EscapeString(text))
|
||
|
|
}
|
||
|
|
|
||
|
|
func normalizeDegree180(value float64) float64 {
|
||
|
|
value = math.Mod(value+180, 360)
|
||
|
|
if value < 0 {
|
||
|
|
value += 360
|
||
|
|
}
|
||
|
|
return value - 180
|
||
|
|
}
|