From 668124d25c6fb3e23fc472dd4b8481eee94b0561 Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Tue, 5 Dec 2023 20:01:25 +0900
Subject: [PATCH] text/v2: add a non-image glyphs for index info

---
 examples/text/main.go |  3 +++
 text/v2/gotext.go     | 20 ++++++++++----------
 text/v2/layout.go     |  3 +++
 text/v2/std.go        | 26 ++++++++++++++------------
 4 files changed, 30 insertions(+), 22 deletions(-)

diff --git a/examples/text/main.go b/examples/text/main.go
index 2bbcb92d6..8a0090d21 100644
--- a/examples/text/main.go
+++ b/examples/text/main.go
@@ -125,6 +125,9 @@ func (g *Game) Draw(screen *ebiten.Image) {
 		// You can customize how to render each glyph.
 		// In this example, multiple colors are used to render glyphs.
 		for i, gl := range g.glyphs {
+			if gl.Image == nil {
+				continue
+			}
 			op.GeoM.Reset()
 			op.GeoM.Translate(x, y)
 			op.GeoM.Translate(gl.X, gl.Y)
diff --git a/text/v2/gotext.go b/text/v2/gotext.go
index 9e709d069..0ad63d92f 100644
--- a/text/v2/gotext.go
+++ b/text/v2/gotext.go
@@ -300,16 +300,16 @@ func (g *GoTextFace) appendGlyphsForLine(glyphs []Glyph, line string, indexOffse
 	_, gs := g.Source.shape(line, g)
 	for _, glyph := range gs {
 		img, imgX, imgY := g.glyphImage(glyph, origin)
-		if img != nil {
-			glyphs = append(glyphs, Glyph{
-				StartIndexInBytes: indexOffset + glyph.startIndex,
-				EndIndexInBytes:   indexOffset + glyph.endIndex,
-				GID:               uint32(glyph.shapingGlyph.GlyphID),
-				Image:             img,
-				X:                 float64(imgX),
-				Y:                 float64(imgY),
-			})
-		}
+		// Append a glyph even if img is nil.
+		// This is necessary to return index information for control characters.
+		glyphs = append(glyphs, Glyph{
+			StartIndexInBytes: indexOffset + glyph.startIndex,
+			EndIndexInBytes:   indexOffset + glyph.endIndex,
+			GID:               uint32(glyph.shapingGlyph.GlyphID),
+			Image:             img,
+			X:                 float64(imgX),
+			Y:                 float64(imgY),
+		})
 		origin = origin.Add(fixed.Point26_6{
 			X: glyph.shapingGlyph.XAdvance,
 			Y: -glyph.shapingGlyph.YAdvance,
diff --git a/text/v2/layout.go b/text/v2/layout.go
index eeb251864..fdb7e1ed6 100644
--- a/text/v2/layout.go
+++ b/text/v2/layout.go
@@ -106,6 +106,9 @@ func Draw(dst *ebiten.Image, text string, face Face, options *DrawOptions) {
 
 	geoM := options.GeoM
 	for _, g := range AppendGlyphs(nil, text, face, &options.LayoutOptions) {
+		if g.Image == nil {
+			continue
+		}
 		op := &options.DrawImageOptions
 		op.GeoM.Reset()
 		op.GeoM.Translate(g.X, g.Y)
diff --git a/text/v2/std.go b/text/v2/std.go
index 46cfaeded..4c8703d91 100644
--- a/text/v2/std.go
+++ b/text/v2/std.go
@@ -108,18 +108,20 @@ func (s *StdFace) appendGlyphsForLine(glyphs []Glyph, line string, indexOffset i
 			origin.X += s.f.Kern(prevR, r)
 		}
 		img, imgX, imgY, a := s.glyphImage(r, origin)
-		if img != nil {
-			// Adjust the position to the integers.
-			// The current glyph images assume that they are rendered on integer positions so far.
-			_, size := utf8.DecodeRuneInString(line[i:])
-			glyphs = append(glyphs, Glyph{
-				StartIndexInBytes: indexOffset + i,
-				EndIndexInBytes:   indexOffset + i + size,
-				Image:             img,
-				X:                 float64(imgX),
-				Y:                 float64(imgY),
-			})
-		}
+
+		// Adjust the position to the integers.
+		// The current glyph images assume that they are rendered on integer positions so far.
+		_, size := utf8.DecodeRuneInString(line[i:])
+
+		// Append a glyph even if img is nil.
+		// This is necessary to return index information for control characters.
+		glyphs = append(glyphs, Glyph{
+			StartIndexInBytes: indexOffset + i,
+			EndIndexInBytes:   indexOffset + i + size,
+			Image:             img,
+			X:                 float64(imgX),
+			Y:                 float64(imgY),
+		})
 		origin.X += a
 		prevR = r
 	}