ryan
6a70135a5d
Generates a branded 1200x630 PNG per event with title, date/time/location using Go's image package and a custom bitmap font. Supports BBQ_BASE_URL env var for absolute URLs required by link preview crawlers. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
225 lines
7.4 KiB
Go
225 lines
7.4 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/draw"
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"image/png"
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"net/http"
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"github.com/go-chi/chi/v5"
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)
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var (
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ogCream = color.RGBA{0xf5, 0xf0, 0xe8, 0xff}
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ogInk = color.RGBA{0x1a, 0x1a, 0x1a, 0xff}
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ogYellow = color.RGBA{0xf5, 0xe6, 0x42, 0xff}
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ogSage = color.RGBA{0xa8, 0xc5, 0xa0, 0xff}
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ogPeach = color.RGBA{0xf2, 0xa4, 0x82, 0xff}
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ogWhite = color.RGBA{0xff, 0xff, 0xff, 0xff}
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)
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func fillRect(img *image.RGBA, x1, y1, x2, y2 int, c color.RGBA) {
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draw.Draw(img, image.Rect(x1, y1, x2, y2), &image.Uniform{c}, image.Point{}, draw.Src)
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}
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// 5x7 pixel font for uppercase letters, digits, and a few symbols
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var glyphs = map[rune][7]uint8{
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'A': {0b01110, 0b10001, 0b10001, 0b11111, 0b10001, 0b10001, 0b10001},
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'B': {0b11110, 0b10001, 0b10001, 0b11110, 0b10001, 0b10001, 0b11110},
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'C': {0b01110, 0b10001, 0b10000, 0b10000, 0b10000, 0b10001, 0b01110},
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'D': {0b11110, 0b10001, 0b10001, 0b10001, 0b10001, 0b10001, 0b11110},
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'E': {0b11111, 0b10000, 0b10000, 0b11110, 0b10000, 0b10000, 0b11111},
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'F': {0b11111, 0b10000, 0b10000, 0b11110, 0b10000, 0b10000, 0b10000},
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'G': {0b01110, 0b10001, 0b10000, 0b10111, 0b10001, 0b10001, 0b01110},
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'H': {0b10001, 0b10001, 0b10001, 0b11111, 0b10001, 0b10001, 0b10001},
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'I': {0b11111, 0b00100, 0b00100, 0b00100, 0b00100, 0b00100, 0b11111},
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'J': {0b00111, 0b00010, 0b00010, 0b00010, 0b00010, 0b10010, 0b01100},
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'K': {0b10001, 0b10010, 0b10100, 0b11000, 0b10100, 0b10010, 0b10001},
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'L': {0b10000, 0b10000, 0b10000, 0b10000, 0b10000, 0b10000, 0b11111},
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'M': {0b10001, 0b11011, 0b10101, 0b10101, 0b10001, 0b10001, 0b10001},
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'N': {0b10001, 0b11001, 0b10101, 0b10011, 0b10001, 0b10001, 0b10001},
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'O': {0b01110, 0b10001, 0b10001, 0b10001, 0b10001, 0b10001, 0b01110},
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'P': {0b11110, 0b10001, 0b10001, 0b11110, 0b10000, 0b10000, 0b10000},
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'Q': {0b01110, 0b10001, 0b10001, 0b10001, 0b10101, 0b10010, 0b01101},
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'R': {0b11110, 0b10001, 0b10001, 0b11110, 0b10100, 0b10010, 0b10001},
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'S': {0b01110, 0b10001, 0b10000, 0b01110, 0b00001, 0b10001, 0b01110},
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'T': {0b11111, 0b00100, 0b00100, 0b00100, 0b00100, 0b00100, 0b00100},
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'U': {0b10001, 0b10001, 0b10001, 0b10001, 0b10001, 0b10001, 0b01110},
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'V': {0b10001, 0b10001, 0b10001, 0b10001, 0b10001, 0b01010, 0b00100},
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'W': {0b10001, 0b10001, 0b10001, 0b10101, 0b10101, 0b11011, 0b10001},
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'X': {0b10001, 0b10001, 0b01010, 0b00100, 0b01010, 0b10001, 0b10001},
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'Y': {0b10001, 0b10001, 0b01010, 0b00100, 0b00100, 0b00100, 0b00100},
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'Z': {0b11111, 0b00001, 0b00010, 0b00100, 0b01000, 0b10000, 0b11111},
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'0': {0b01110, 0b10001, 0b10011, 0b10101, 0b11001, 0b10001, 0b01110},
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'1': {0b00100, 0b01100, 0b00100, 0b00100, 0b00100, 0b00100, 0b11111},
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'2': {0b01110, 0b10001, 0b00001, 0b00110, 0b01000, 0b10000, 0b11111},
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'3': {0b01110, 0b10001, 0b00001, 0b00110, 0b00001, 0b10001, 0b01110},
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'4': {0b00010, 0b00110, 0b01010, 0b10010, 0b11111, 0b00010, 0b00010},
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'5': {0b11111, 0b10000, 0b11110, 0b00001, 0b00001, 0b10001, 0b01110},
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'6': {0b01110, 0b10000, 0b10000, 0b11110, 0b10001, 0b10001, 0b01110},
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'7': {0b11111, 0b00001, 0b00010, 0b00100, 0b01000, 0b01000, 0b01000},
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'8': {0b01110, 0b10001, 0b10001, 0b01110, 0b10001, 0b10001, 0b01110},
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'9': {0b01110, 0b10001, 0b10001, 0b01111, 0b00001, 0b00001, 0b01110},
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' ': {0b00000, 0b00000, 0b00000, 0b00000, 0b00000, 0b00000, 0b00000},
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'\'': {0b00100, 0b00100, 0b01000, 0b00000, 0b00000, 0b00000, 0b00000},
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'.': {0b00000, 0b00000, 0b00000, 0b00000, 0b00000, 0b00000, 0b00100},
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',': {0b00000, 0b00000, 0b00000, 0b00000, 0b00000, 0b00100, 0b01000},
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'!': {0b00100, 0b00100, 0b00100, 0b00100, 0b00100, 0b00000, 0b00100},
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'?': {0b01110, 0b10001, 0b00001, 0b00110, 0b00100, 0b00000, 0b00100},
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'-': {0b00000, 0b00000, 0b00000, 0b11111, 0b00000, 0b00000, 0b00000},
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'#': {0b01010, 0b01010, 0b11111, 0b01010, 0b11111, 0b01010, 0b01010},
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'/': {0b00001, 0b00010, 0b00010, 0b00100, 0b01000, 0b01000, 0b10000},
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':': {0b00000, 0b00100, 0b00000, 0b00000, 0b00000, 0b00100, 0b00000},
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'@': {0b01110, 0b10001, 0b10111, 0b10101, 0b10110, 0b10000, 0b01110},
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'+': {0b00000, 0b00100, 0b00100, 0b11111, 0b00100, 0b00100, 0b00000},
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'&': {0b01100, 0b10010, 0b10100, 0b01000, 0b10101, 0b10010, 0b01101},
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}
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func drawText(img *image.RGBA, text string, x, y, scale int, c color.RGBA) int {
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cx := x
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for _, ch := range text {
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if ch >= 'a' && ch <= 'z' {
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ch = ch - 'a' + 'A'
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}
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glyph, ok := glyphs[ch]
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if !ok {
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cx += 4 * scale // skip unknown chars
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continue
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}
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for row := 0; row < 7; row++ {
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for col := 0; col < 5; col++ {
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if glyph[row]&(1<<(4-col)) != 0 {
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fillRect(img, cx+col*scale, y+row*scale, cx+(col+1)*scale, y+(row+1)*scale, c)
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}
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}
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}
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cx += 6 * scale // 5 pixels + 1 spacing
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}
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return cx - x
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}
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func textWidth(text string, scale int) int {
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n := 0
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for range text {
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n++
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}
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if n == 0 {
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return 0
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}
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return n*6*scale - scale
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}
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func (s *Server) handleOGImage(w http.ResponseWriter, r *http.Request) {
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slug := chi.URLParam(r, "slug")
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event, err := s.q.GetEventBySlug(r.Context(), slug)
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if err != nil {
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http.NotFound(w, r)
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return
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}
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imgW, imgH := 1200, 630
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img := image.NewRGBA(image.Rect(0, 0, imgW, imgH))
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// Background
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fillRect(img, 0, 0, imgW, imgH, ogCream)
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// Yellow header bar
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fillRect(img, 0, 0, imgW, 80, ogYellow)
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fillRect(img, 0, 78, imgW, 83, ogInk)
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// Logo in header: dark box with emoji-colored inner
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fillRect(img, 40, 16, 88, 64, ogInk)
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fillRect(img, 44, 20, 84, 60, ogYellow)
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drawText(img, "BBQ", 100, 26, 4, ogInk)
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// Center card
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cardX, cardY := 120, 140
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cardW, cardH := imgW-240, 400
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// Shadow
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fillRect(img, cardX+8, cardY+8, cardX+cardW+8, cardY+cardH+8, ogInk)
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// Border
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fillRect(img, cardX-3, cardY-3, cardX+cardW+3, cardY+cardH+3, ogInk)
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// Card
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fillRect(img, cardX, cardY, cardX+cardW, cardY+cardH, ogWhite)
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// Tag pill
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tagText := "POTLUCK"
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tagW := textWidth(tagText, 3) + 24
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fillRect(img, cardX+30-2, cardY+28-2, cardX+30+tagW+2, cardY+28+28+2, ogInk)
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fillRect(img, cardX+30, cardY+28, cardX+30+tagW, cardY+28+28, ogSage)
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drawText(img, tagText, cardX+42, cardY+32, 3, ogInk)
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// Event title - scale to fit
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title := event.Title
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scale := 7
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for scale > 3 {
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if textWidth(title, scale) <= cardW-80 {
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break
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}
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scale--
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}
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// Truncate if still too wide
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for len(title) > 0 && textWidth(title, scale) > cardW-80 {
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title = title[:len(title)-1]
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}
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titleY := cardY + 90
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drawText(img, title, cardX+38, titleY, scale, ogInk)
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// Date/time/location line
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meta := ""
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if event.Date != "" {
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meta = event.Date
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}
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if event.Time != "" {
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if meta != "" {
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meta += " "
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}
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meta += event.Time
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}
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if event.Location != "" {
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if meta != "" {
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meta += " - "
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}
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meta += event.Location
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}
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if meta != "" {
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metaScale := 3
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for len(meta) > 0 && textWidth(meta, metaScale) > cardW-80 {
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meta = meta[:len(meta)-1]
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}
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metaY := titleY + 7*scale + 24
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drawText(img, meta, cardX+38, metaY, metaScale, color.RGBA{0x66, 0x66, 0x66, 0xff})
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}
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// Decorative slot-like bars at the bottom of the card
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barY := cardY + cardH - 100
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bars := []struct {
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w int
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c color.RGBA
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}{
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{320, ogYellow},
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{240, ogSage},
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{280, ogPeach},
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{200, ogYellow},
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}
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for i, b := range bars {
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y := barY + i*22
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fillRect(img, cardX+38, y, cardX+38+b.w, y+14, b.c)
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fillRect(img, cardX+38, y, cardX+38+b.w, y+14, b.c)
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}
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// Bottom accent stripe
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fillRect(img, 0, imgH-14, imgW, imgH-10, ogInk)
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fillRect(img, 0, imgH-10, imgW, imgH, ogYellow)
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var buf bytes.Buffer
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png.Encode(&buf, img)
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w.Header().Set("Content-Type", "image/png")
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w.Header().Set("Cache-Control", "public, max-age=3600")
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w.Write(buf.Bytes())
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}
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