using a custom RunIterator that takes emojis into account and shapes them with a different font.

it doesn't actually work since the different outputs returned are treated by LineWrapper as necessarily belonging to different lines, so we'll have to do something different.

go.mod

@@ -4,11 +4,13 @@ go 1.21.4
 
 require (
 	github.com/PuerkitoBio/goquery v1.5.0
-	github.com/apatters/go-wordwrap v1.0.0
 	github.com/dgraph-io/badger/v4 v4.2.0
+	github.com/dmolesUC3/emoji v0.0.0-20190226181050-1849526eb21f
 	github.com/fiatjaf/eventstore v0.3.3
 	github.com/fiatjaf/khatru v0.2.1
 	github.com/fogleman/gg v1.3.0
+	github.com/go-text/render v0.0.0-20230619120952-35bccb6164b8
+	github.com/go-text/typesetting v0.0.0-20231221124458-48cc05a56658
 	github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0
 	github.com/gomarkdown/markdown v0.0.0-20231115200524-a660076da3fd
 	github.com/kelseyhightower/envconfig v1.4.0
@@ -17,6 +19,7 @@ require (
 	github.com/nbd-wtf/nostr-sdk v0.0.4
 	github.com/nfnt/resize v0.0.0-20180221191011-83c6a9932646
 	github.com/pelletier/go-toml v1.9.5
+	github.com/pemistahl/lingua-go v1.4.0
 	github.com/rs/cors v1.10.0
 	github.com/rs/zerolog v1.29.1
 	github.com/stretchr/testify v1.8.4
@@ -41,8 +44,6 @@ require (
 	github.com/dgraph-io/ristretto v0.1.1 // indirect
 	github.com/dustin/go-humanize v1.0.1 // indirect
 	github.com/fasthttp/websocket v1.5.3 // indirect
-	github.com/go-text/render v0.0.0-20230619120952-35bccb6164b8 // indirect
-	github.com/go-text/typesetting v0.0.0-20231221124458-48cc05a56658 // indirect
 	github.com/gobwas/httphead v0.1.0 // indirect
 	github.com/gobwas/pool v0.2.1 // indirect
 	github.com/gobwas/ws v1.3.1 // indirect
@@ -58,7 +59,6 @@ require (
 	github.com/mailru/easyjson v0.7.7 // indirect
 	github.com/mattn/go-colorable v0.1.12 // indirect
 	github.com/mattn/go-isatty v0.0.14 // indirect
-	github.com/pemistahl/lingua-go v1.4.0 // indirect
 	github.com/pkg/errors v0.9.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/puzpuzpuz/xsync/v2 v2.5.1 // indirect

go.sum

@@ -7,8 +7,6 @@ github.com/andybalholm/brotli v1.0.5 h1:8uQZIdzKmjc/iuPu7O2ioW48L81FgatrcpfFmiq/
 github.com/andybalholm/brotli v1.0.5/go.mod h1:fO7iG3H7G2nSZ7m0zPUDn85XEX2GTukHGRSepvi9Eig=
 github.com/andybalholm/cascadia v1.0.0 h1:hOCXnnZ5A+3eVDX8pvgl4kofXv2ELss0bKcqRySc45o=
 github.com/andybalholm/cascadia v1.0.0/go.mod h1:GsXiBklL0woXo1j/WYWtSYYC4ouU9PqHO0sqidkEA4Y=
-github.com/apatters/go-wordwrap v1.0.0 h1:G6ni4Pt7/I4ED+A5ZvsK8e9XwETD04veDKxEL2QN830=
-github.com/apatters/go-wordwrap v1.0.0/go.mod h1:3sM7HcArQ+utXnjDQ4d1xjrd8b/wbKuDr/RmbiHgjwI=
 github.com/aymerick/douceur v0.2.0 h1:Mv+mAeH1Q+n9Fr+oyamOlAkUNPWPlA8PPGR0QAaYuPk=
 github.com/aymerick/douceur v0.2.0/go.mod h1:wlT5vV2O3h55X9m7iVYN0TBM0NH/MmbLnd30/FjWUq4=
 github.com/btcsuite/btcd v0.20.1-beta/go.mod h1:wVuoA8VJLEcwgqHBwHmzLRazpKxTv13Px/pDuV7OomQ=
@@ -59,6 +57,8 @@ github.com/dgraph-io/ristretto v0.1.1 h1:6CWw5tJNgpegArSHpNHJKldNeq03FQCwYvfMVWa
 github.com/dgraph-io/ristretto v0.1.1/go.mod h1:S1GPSBCYCIhmVNfcth17y2zZtQT6wzkzgwUve0VDWWA=
 github.com/dgryski/go-farm v0.0.0-20190423205320-6a90982ecee2 h1:tdlZCpZ/P9DhczCTSixgIKmwPv6+wP5DGjqLYw5SUiA=
 github.com/dgryski/go-farm v0.0.0-20190423205320-6a90982ecee2/go.mod h1:SqUrOPUnsFjfmXRMNPybcSiG0BgUW2AuFH8PAnS2iTw=
+github.com/dmolesUC3/emoji v0.0.0-20190226181050-1849526eb21f h1:l4W9/rRyCN5QtPsgMvERrQ3mKSsaO/b191TPxe2ROO8=
+github.com/dmolesUC3/emoji v0.0.0-20190226181050-1849526eb21f/go.mod h1:+5FBTP/tHiFB2yrIvWaLq9PchgdvVu99lBK5ZrEzl9w=
 github.com/dustin/go-humanize v1.0.0/go.mod h1:HtrtbFcZ19U5GC7JDqmcUSB87Iq5E25KnS6fMYU6eOk=
 github.com/dustin/go-humanize v1.0.1 h1:GzkhY7T5VNhEkwH0PVJgjz+fX1rhBrR7pRT3mDkpeCY=
 github.com/dustin/go-humanize v1.0.1/go.mod h1:Mu1zIs6XwVuF/gI1OepvI0qD18qycQx+mFykh5fBlto=
@@ -78,10 +78,10 @@ github.com/fsnotify/fsnotify v1.4.7/go.mod h1:jwhsz4b93w/PPRr/qN1Yymfu8t87LnFCMo
 github.com/fsnotify/fsnotify v1.4.9/go.mod h1:znqG4EE+3YCdAaPaxE2ZRY/06pZUdp0tY4IgpuI1SZQ=
 github.com/go-text/render v0.0.0-20230619120952-35bccb6164b8 h1:VkKnvzbvHqgEfm351rfr8Uclu5fnwq8HP2ximUzJsBM=
 github.com/go-text/render v0.0.0-20230619120952-35bccb6164b8/go.mod h1:h29xCucjNsDcYb7+0rJokxVwYAq+9kQ19WiFuBKkYtc=
-github.com/go-text/typesetting v0.0.0-20230616162802-9c17dd34aa4a h1:VjN8ttdfklC0dnAdKbZqGNESdERUxtE3l8a/4Grgarc=
-github.com/go-text/typesetting v0.0.0-20230616162802-9c17dd34aa4a/go.mod h1:evDBbvNR/KaVFZ2ZlDSOWWXIUKq0wCOEtzLxRM8SG3k=
 github.com/go-text/typesetting v0.0.0-20231221124458-48cc05a56658 h1:KeDKnC99J3l5qJK4zV13Au2UwPn4N20TnIlM0YvILj8=
 github.com/go-text/typesetting v0.0.0-20231221124458-48cc05a56658/go.mod h1:d22AnmeKq/on0HNv73UFriMKc4Ez6EqZAofLhAzpSzI=
+github.com/go-text/typesetting-utils v0.0.0-20231211103740-d9332ae51f04 h1:zBx+p/W2aQYtNuyZNcTfinWvXBQwYtDfme051PR/lAY=
+github.com/go-text/typesetting-utils v0.0.0-20231211103740-d9332ae51f04/go.mod h1:DDxDdQEnB70R8owOx3LVpEFvpMK9eeH1o2r0yZhFI9o=
 github.com/gobwas/httphead v0.1.0 h1:exrUm0f4YX0L7EBwZHuCF4GDp8aJfVeBrlLQrs6NqWU=
 github.com/gobwas/httphead v0.1.0/go.mod h1:O/RXo79gxV8G+RqlR/otEwx4Q36zl9rqC5u12GKvMCM=
 github.com/gobwas/pool v0.2.1 h1:xfeeEhW7pwmX8nuLVlqbzVc7udMDrwetjEv+TZIz1og=
@@ -146,6 +146,8 @@ github.com/klauspost/compress v1.17.2 h1:RlWWUY/Dr4fL8qk9YG7DTZ7PDgME2V4csBXA8L/
 github.com/klauspost/compress v1.17.2/go.mod h1:ntbaceVETuRiXiv4DpjP66DpAtAGkEQskQzEyD//IeE=
 github.com/kr/pretty v0.1.0 h1:L/CwN0zerZDmRFUapSPitk6f+Q3+0za1rQkzVuMiMFI=
 github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
+github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
+github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
 github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
 github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
 github.com/mailru/easyjson v0.7.7 h1:UGYAvKxe3sBsEDzO8ZeWOSlIQfWFlxbzLZe7hwFURr0=
@@ -200,7 +202,6 @@ github.com/srwiley/rasterx v0.0.0-20220730225603-2ab79fcdd4ef/go.mod h1:nXTWP6+g
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSSt89Yw=
 github.com/stretchr/objx v0.5.0/go.mod h1:Yh+to48EsGEfYuaHDzXPcE3xhTkx73EhmCGUpEOglKo=
-github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
 github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
@@ -323,6 +324,7 @@ google.golang.org/protobuf v1.26.0/go.mod h1:9q0QmTI4eRPtz6boOQmLYwt+qCgq0jsYwAQ
 google.golang.org/protobuf v1.31.0 h1:g0LDEJHgrBl9N9r17Ru3sqWhkIx2NB67okBHPwC7hs8=
 google.golang.org/protobuf v1.31.0/go.mod h1:HV8QOd/L58Z+nl8r43ehVNZIU/HEI6OcFqwMG9pJV4I=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c/go.mod h1:JHkPIbrfpd72SG/EVd6muEfDQjcINNoR0C8j2r3qZ4Q=
 gopkg.in/fsnotify.v1 v1.4.7/go.mod h1:Tz8NjZHkW78fSQdbUxIjBTcgA1z1m8ZHf0WmKUhAMys=

image_utils.go

@@ -12,11 +12,14 @@ import (
 	"strings"
 	"time"
 
+	"github.com/dmolesUC3/emoji"
 	"github.com/fogleman/gg"
 	"github.com/go-text/typesetting/di"
 	"github.com/go-text/typesetting/font"
 	"github.com/go-text/typesetting/language"
+	"github.com/go-text/typesetting/shaping"
 	"github.com/pemistahl/lingua-go"
+	"golang.org/x/image/math/fixed"
 )
 
 const nSupportedScripts = 13
@@ -325,3 +328,81 @@ func shortenURLs(text string) string {
 		return strings.Replace(urlStr, "/////", strings.Join(pathParts, "/"), 1)
 	})
 }
+
+type shapedOutputIterator struct {
+	rawText   []rune
+	idx       int
+	savedIdx  int
+	shaper    *shaping.HarfbuzzShaper
+	fontSize  int
+	face      font.Face
+	language  language.Language
+	script    language.Script
+	direction di.Direction
+}
+
+var _ shaping.RunIterator = (*shapedOutputIterator)(nil)
+
+func (it *shapedOutputIterator) Next() (int, shaping.Output, bool) {
+	idx, nextIdx, run, ok := it.readNext()
+	if ok {
+		it.idx = nextIdx
+	}
+	return idx, run, ok
+}
+
+func (it *shapedOutputIterator) Peek() (int, shaping.Output, bool) {
+	idx, _, out, more := it.readNext()
+	return idx, out, more
+}
+
+func (it *shapedOutputIterator) readNext() (int, int, shaping.Output, bool) {
+	if it.idx >= len(it.rawText) {
+		return it.idx, -1, shaping.Output{}, false
+	}
+
+	// if the next character is an emoji then return a block of emojis
+	if emoji.IsEmoji(it.rawText[it.idx]) {
+		shapedEmoji := it.shaper.Shape(shaping.Input{
+			Text:      it.rawText,
+			RunStart:  it.idx,
+			RunEnd:    it.idx + 1,
+			Face:      emojiFont,
+			Size:      fixed.I(int(it.fontSize)),
+			Script:    it.script,
+			Language:  it.language,
+			Direction: it.direction,
+		})
+		return it.idx, it.idx + 1, shapedEmoji, true
+	}
+	// otherwise we consume runes until we find an emoji and return everything
+
+	var runesConsumed int = 0
+	for r, rn := range it.rawText[it.idx:] {
+		if emoji.IsEmoji(rn) {
+			// reached an emoji, stop now
+			break
+		}
+		runesConsumed = r
+	}
+
+	shapedRunes := it.shaper.Shape(shaping.Input{
+		Text:      it.rawText,
+		RunStart:  it.idx,
+		RunEnd:    it.idx + runesConsumed + 1,
+		Face:      it.face,
+		Size:      fixed.I(int(it.fontSize)),
+		Script:    it.script,
+		Language:  it.language,
+		Direction: it.direction,
+	})
+	return it.idx, it.idx + runesConsumed + 1, shapedRunes, true
+}
+
+func (it *shapedOutputIterator) Save() {
+	it.savedIdx = it.idx
+}
+
+func (it *shapedOutputIterator) Restore() {
+	it.idx = it.savedIdx
+}

render_image.go

@@ -19,7 +19,6 @@ import (
 	sdk "github.com/nbd-wtf/nostr-sdk"
 	"github.com/nfnt/resize"
 	xfont "golang.org/x/image/font"
-	"golang.org/x/image/math/fixed"
 )
 
 const (
@@ -183,24 +182,24 @@ func drawText(paragraphs []string, width, height int) image.Image {
 
 	i := 1
 	for _, paragraph := range paragraphs {
-		text := []rune(paragraph)
+		rawText := []rune(paragraph)
+		if len(rawText) == 0 {
+			rawText = []rune{' '}
+		}
 
-		lang, script, dir, face := getLanguageAndScriptAndDirectionAndFont(text)
+		lang, script, dir, face := getLanguageAndScriptAndDirectionAndFont(rawText)
-		shaper := &shaping.HarfbuzzShaper{}
+		iterator := &shapedOutputIterator{
-
+			rawText:   rawText,
-		shapedRunes := shaper.Shape(shaping.Input{
+			shaper:    &shaping.HarfbuzzShaper{},
-			Text:      text,
+			fontSize:  FONT_SIZE,
-			RunStart:  0,
+			language:  lang,
-			RunEnd:    len(text),
+			script:    script,
-			Face:      face,
+			direction: dir,
-			Size:      fixed.I(int(r.FontSize)),
+			face:      face,
-			Script:    script,
+		}
-			Language:  lang,
-			Direction: dir,
-		})
 
 		var wrapper shaping.LineWrapper
-		lines, _ := wrapper.WrapParagraph(shaping.WrapConfig{}, width, []rune(text), shaping.NewSliceIterator([]shaping.Output{shapedRunes}))
+		lines, _ := wrapper.WrapParagraph(shaping.WrapConfig{}, width, rawText, iterator)
 
 		for _, line := range lines {
 			for _, out := range line {