b612
16c62a97d5
- 新增时标、ΔT 模型、质心时间与 UT1 支持 - 改进日月食、月掩、行星事件及路径边界计算 - 完善恒星三维自行与动态距离传播 - 扩展 SVG、GeoJSON、KML 输出与底层距离换算工具 - 整理中英文手册、示例资源及回归测试
121 lines
3.3 KiB
Go
121 lines
3.3 KiB
Go
// Package timenote 生成出图时写入图内或图注的时标声明。
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package timenote
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import (
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"fmt"
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"strconv"
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"strings"
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"time"
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"b612.me/astro"
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)
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const english = "en"
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// Scale 生成图内时标声明：UTC 口径写显示时区与 UTC 偏移，UT1 口径补 DUT1 差值 / builds the in-figure time-scale declaration.
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func Scale(scale astro.TimeScale, instant time.Time, location *time.Location, language string) string {
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if scale == astro.TimeScaleUT1 {
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dut1 := astro.DUT1(instant)
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if language == english {
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return fmt.Sprintf("Times are UT1 (Universal Time 1); DUT1 = UT1−UTC = %+.2f s.", dut1)
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}
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return fmt.Sprintf("图中时刻为 UT1（世界时），DUT1 = UT1−UTC = %+.2f s。", dut1)
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}
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zone, offset := displayZone(instant, location)
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if offset == 0 {
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if language == english {
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return "All times are UTC"
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}
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return "图中时刻为 UTC"
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}
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if named, ok := namedZoneOffset(zone); ok && named == offset {
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// 时区名本身就是偏移标签（FixedZone("UTC+08:00")、"Etc/GMT+8" 之类）时再写一遍偏移就是重复文案。
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if language == english {
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return fmt.Sprintf("All times are UTC (shown in %s)", zone)
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}
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return fmt.Sprintf("图中时刻为 UTC（显示时区 %s）", zone)
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}
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sign := "+"
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if offset < 0 {
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sign, offset = "-", -offset
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}
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hours, minutes := offset/3600, offset%3600/60
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if language == english {
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return fmt.Sprintf("All times are UTC (shown in %s, UTC%s%02d:%02d)", zone, sign, hours, minutes)
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}
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return fmt.Sprintf("图中时刻为 UTC（显示时区 %s，UTC%s%02d:%02d）", zone, sign, hours, minutes)
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}
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// Merge 把时标声明并进图注，已含声明时不重复 / appends the declaration to a footer note once.
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func Merge(text, note string) string {
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if note == "" {
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return text
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}
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if text == "" {
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return note
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}
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if strings.Contains(text, note) {
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return text
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}
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return text + " " + note
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}
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// namedZoneOffset 解析时区名里写死的 UTC 偏移，秒为单位；名字不含偏移时返回 false。
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func namedZoneOffset(name string) (int, bool) {
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rest := strings.ToUpper(name)
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for _, prefix := range []string{"UTC", "GMT", "UT"} {
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if strings.HasPrefix(rest, prefix) {
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rest = rest[len(prefix):]
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break
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}
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}
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if rest == "" {
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return 0, false
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}
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sign := 1
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switch rest[0] {
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case '+':
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rest = rest[1:]
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case '-':
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sign, rest = -1, rest[1:]
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default:
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return 0, false
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}
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digits := strings.ReplaceAll(rest, ":", "")
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if digits == "" || len(digits) > 6 {
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return 0, false
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}
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for _, symbol := range digits {
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if symbol < '0' || symbol > '9' {
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return 0, false
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}
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}
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hours, minutes, seconds := 0, 0, 0
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switch len(digits) {
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case 1, 2:
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hours, _ = strconv.Atoi(digits)
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case 3, 4:
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hours, _ = strconv.Atoi(digits[:len(digits)-2])
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minutes, _ = strconv.Atoi(digits[len(digits)-2:])
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case 5, 6:
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hours, _ = strconv.Atoi(digits[:len(digits)-4])
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minutes, _ = strconv.Atoi(digits[len(digits)-4 : len(digits)-2])
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seconds, _ = strconv.Atoi(digits[len(digits)-2:])
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}
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if minutes > 59 || seconds > 59 {
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return 0, false
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}
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return sign * (hours*3600 + minutes*60 + seconds), true
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}
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func displayZone(instant time.Time, location *time.Location) (string, int) {
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if location != nil {
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instant = instant.In(location)
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}
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zone, offset := instant.Zone()
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if zone == "" {
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zone = "UTC"
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}
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return zone, offset
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}
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