Conrad Schulz
641312aba9
- Non-square canvas (pin-m: 27x41 @1x = 54x82 @2x, Maptiler standard) - r=37% of width -> circle fills 74% of canvas width - r/d=0.37 -> 22deg opening angle (Google Maps standard) - White border: borderW=max(2px,8%width), A=255 (fully opaque) - White inner dot: r*0.38, A=255 (fully opaque, clearly visible) - Fill: 85% opacity (A=217)
263 lines
7.2 KiB
Go
263 lines
7.2 KiB
Go
package main
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import (
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"bytes"
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"image"
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"image/color"
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"image/png"
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"log"
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"math"
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"net/http"
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"os"
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"regexp"
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"sort"
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"strconv"
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"strings"
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"sync"
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)
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// URL-Muster: /styles/v4/marker/{type}+{hexcolor}(@{scale}x).png
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var markerPattern = regexp.MustCompile(
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`^/styles/v4/marker/([a-z-]+)\+([0-9a-fA-F]{6})(?:@(\d+(?:\.\d+)?x))?\.png$`,
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)
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// Basis-Abmessungen (Breite × Höhe) – entspricht Maptiler-Standard.
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// Der Pin ankert an der Spitze (bottom-center), nicht am Bildmittelpunkt.
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type pinDims struct{ w, h float64 }
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var baseSizes = map[string]pinDims{
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"pin-s": {20, 30},
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"pin-m": {27, 41}, // Maptiler-Standard
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"pin-l": {34, 52},
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}
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// Marker-Cache (max 500 Einträge, reicht für alle Farb/Typ/Scale-Kombinationen)
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var (
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markerCache = make(map[string][]byte)
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markerCacheMu sync.RWMutex
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)
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func hexToColor(h string) color.RGBA {
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r, _ := strconv.ParseUint(h[0:2], 16, 8)
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g, _ := strconv.ParseUint(h[2:4], 16, 8)
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b, _ := strconv.ParseUint(h[4:6], 16, 8)
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return color.RGBA{R: uint8(r), G: uint8(g), B: uint8(b), A: 255}
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}
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// fillPolygon füllt ein Polygon mit dem Scanline-Algorithmus
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func fillPolygon(img *image.RGBA, pts [][2]float64, c color.RGBA) {
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if len(pts) < 3 {
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return
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}
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bounds := img.Bounds()
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minY, maxY := pts[0][1], pts[0][1]
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for _, p := range pts {
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if p[1] < minY {
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minY = p[1]
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}
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if p[1] > maxY {
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maxY = p[1]
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}
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}
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n := len(pts)
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for scanY := int(math.Floor(minY)); scanY <= int(math.Ceil(maxY)); scanY++ {
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if scanY < bounds.Min.Y || scanY >= bounds.Max.Y {
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continue
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}
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y := float64(scanY) + 0.5
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var xs []float64
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for i := 0; i < n; i++ {
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p1, p2 := pts[i], pts[(i+1)%n]
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if (p1[1] <= y && p2[1] > y) || (p2[1] <= y && p1[1] > y) {
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x := p1[0] + (y-p1[1])/(p2[1]-p1[1])*(p2[0]-p1[0])
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xs = append(xs, x)
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}
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}
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sort.Float64s(xs)
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for i := 0; i+1 < len(xs); i += 2 {
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x0 := int(math.Round(xs[i]))
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x1 := int(math.Round(xs[i+1]))
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for x := x0; x <= x1; x++ {
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if x >= bounds.Min.X && x < bounds.Max.X {
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img.SetRGBA(x, scanY, c)
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}
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}
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}
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}
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}
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// drawCircle zeichnet einen gefüllten Kreis
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func drawCircle(img *image.RGBA, cx, cy, r float64, c color.RGBA) {
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bounds := img.Bounds()
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for y := int(math.Floor(cy - r)); y <= int(math.Ceil(cy+r)); y++ {
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for x := int(math.Floor(cx - r)); x <= int(math.Ceil(cx+r)); x++ {
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if !image.Pt(x, y).In(bounds) {
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continue
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}
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dx := float64(x) + 0.5 - cx
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dy := float64(y) + 0.5 - cy
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if dx*dx+dy*dy <= r*r {
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img.SetRGBA(x, y, c)
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}
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}
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}
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}
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// pinOutline erzeugt den Umriss eines Google-Maps-artigen Pins:
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// Kreis oben, gerade Seiten (tangential) laufen in einer Spitze zusammen.
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// Mathematisch korrekt: die Seiten sind exakt die Tangenten vom Tip-Punkt an den Kreis.
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func pinOutline(cx, cy, r, tipY float64, numArcPts int) [][2]float64 {
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d := tipY - cy // vertikaler Abstand: Kreismittelpunkt → Spitze
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if d <= r {
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// Fallback: Spitze zu nah am Kreis → einfaches Dreieck
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return [][2]float64{{cx - r, cy}, {cx + r, cy}, {cx, tipY}}
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}
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// Winkel, um den die Tangente von der Senkrechten abweicht
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alpha := math.Asin(r / d)
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// Berührpunkte auf dem Kreis (im Bild-Koordinatensystem: 0°=rechts, 90°=unten)
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rightAngle := math.Pi/2 - alpha // rechter Berührpunkt (~63°)
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leftAngle := math.Pi/2 + alpha // linker Berührpunkt (~117°)
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var pts [][2]float64
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// Bogen vom rechten Berührpunkt, gegen den Uhrzeigersinn durch den Scheitel (270°),
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// zum linken Berührpunkt.
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// arcSpan = rightAngle + 2π - leftAngle (entgegen dem Uhrzeigersinn)
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arcSpan := rightAngle + 2*math.Pi - leftAngle
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for i := 0; i <= numArcPts; i++ {
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t := float64(i) / float64(numArcPts)
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angle := rightAngle - t*arcSpan
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pts = append(pts, [2]float64{
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cx + r*math.Cos(angle),
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cy + r*math.Sin(angle),
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})
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}
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// Abschlusspunkt: die Spitze des Pins
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pts = append(pts, [2]float64{cx, tipY})
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return pts
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}
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// generateMarker erzeugt einen Google-Maps-artigen Pin als PNG
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func generateMarker(pinType, hexColor string, scale float64) ([]byte, error) {
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cacheKey := pinType + "-" + hexColor + "-" + strconv.FormatFloat(scale, 'f', 2, 64)
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markerCacheMu.RLock()
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if cached, ok := markerCache[cacheKey]; ok {
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markerCacheMu.RUnlock()
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return cached, nil
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}
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markerCacheMu.RUnlock()
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bs, ok := baseSizes[pinType]
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if !ok {
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bs = baseSizes["pin-m"]
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}
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w := math.Round(bs.w * scale)
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h := math.Round(bs.h * scale)
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if w < 10 {
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w = 10
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}
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if h < 15 {
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h = 15
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}
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// Geometrie: Kreis füllt ~74% der Breite, r/d ≈ 0.37 → Öffnungswinkel 22°
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// Entspricht exakt Maptiler pin-m Proportionen (27×41px @1x)
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cx := w / 2
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r := w * 0.37 // Kreisradius: Kreis fast so breit wie Canvas
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cy := r + h*0.04 // Kreismittelpunkt Y: kleiner oberer Rand
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tipY := h - h*0.03 // Spitze Y: 3% Abstand vom unteren Rand
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borderW := math.Max(2.0, w*0.08) // weißer Rand: gut sichtbar
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innerR := r * 0.38 // weißer Innenpunkt: 38% des Kreisradius
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// Füllfarbe: 85% opak; Rand und Punkt: vollständig weiß
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fillBase := hexToColor(hexColor)
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fill := color.RGBA{R: fillBase.R, G: fillBase.G, B: fillBase.B, A: 217}
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white := color.RGBA{R: 255, G: 255, B: 255, A: 255}
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img := image.NewRGBA(image.Rect(0, 0, int(math.Ceil(w)), int(math.Ceil(h))))
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// 1. Weißer Rand (Pin mit borderW größerem Radius)
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borderPts := pinOutline(cx, cy, r+borderW, tipY, 64)
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fillPolygon(img, borderPts, white)
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// 2. Farbige Pin-Form
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fillPts := pinOutline(cx, cy, r, tipY, 64)
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fillPolygon(img, fillPts, fill)
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// 3. Weißer Innenpunkt – vollständig opak für gute Sichtbarkeit
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drawCircle(img, cx, cy, innerR, white)
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var buf bytes.Buffer
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if err := png.Encode(&buf, img); err != nil {
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return nil, err
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}
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result := buf.Bytes()
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markerCacheMu.Lock()
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if len(markerCache) < 500 {
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markerCache[cacheKey] = result
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}
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markerCacheMu.Unlock()
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return result, nil
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}
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func handleMarker(w http.ResponseWriter, r *http.Request) {
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matches := markerPattern.FindStringSubmatch(r.URL.Path)
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if matches == nil {
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http.NotFound(w, r)
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return
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}
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pinType := matches[1]
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hexColor := matches[2]
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scaleStr := matches[3]
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scale := 1.0
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if scaleStr != "" {
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if s, err := strconv.ParseFloat(strings.TrimSuffix(scaleStr, "x"), 64); err == nil && s > 0 && s <= 4 {
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scale = s
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}
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}
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log.Printf("marker type=%s color=#%s scale=%.1f", pinType, hexColor, scale)
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data, err := generateMarker(pinType, hexColor, scale)
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if err != nil {
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log.Printf("error generating marker: %v", err)
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http.Error(w, "internal error", http.StatusInternalServerError)
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return
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}
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w.Header().Set("Content-Type", "image/png")
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w.Header().Set("Cache-Control", "public, max-age=2592000, immutable")
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w.Header().Set("Access-Control-Allow-Origin", "*")
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w.Header().Set("Content-Length", strconv.Itoa(len(data)))
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w.WriteHeader(http.StatusOK)
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_, _ = w.Write(data)
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}
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func handleHealth(w http.ResponseWriter, _ *http.Request) {
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w.Header().Set("Content-Type", "application/json")
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_, _ = w.Write([]byte(`{"status":"ok","service":"marker-api"}`))
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}
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func main() {
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port := os.Getenv("PORT")
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if port == "" {
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port = "3000"
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}
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mux := http.NewServeMux()
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mux.HandleFunc("/health", handleHealth)
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mux.HandleFunc("/styles/v4/marker/", handleMarker)
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log.Printf("marker-api listening on :%s", port)
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if err := http.ListenAndServe(":"+port, mux); err != nil {
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log.Fatal(err)
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}
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}
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