2 files changed, 51 insertions(+), 3 deletions(-)

M text/gotext_test.go
M text/shaper.go

@@ 1,11 1,14 @@
 package text
 
 import (
+	"fmt"
 	"math"
 	"reflect"
+	"strconv"
 	"testing"
 
 	nsareg "eliasnaur.com/font/noto/sans/arabic/regular"
+	"github.com/go-text/typesetting/font"
 	"github.com/go-text/typesetting/shaping"
 	"golang.org/x/image/font/gofont/goregular"
 	"golang.org/x/image/math/fixed"


@@ 740,3 743,50 @@ func TestClosestFontByWeight(t *testing.T) {
 		}
 	}
 }
+
+func TestGlyphIDPacking(t *testing.T) {
+	const maxPPem = fixed.Int26_6((1 << sizebits) - 1)
+	type testcase struct {
+		name      string
+		ppem      fixed.Int26_6
+		faceIndex int
+		gid       font.GID
+		expected  GlyphID
+	}
+	for _, tc := range []testcase{
+		{
+			name: "zero value",
+		},
+		{
+			name:      "10 ppem faceIdx 1 GID 5",
+			ppem:      fixed.I(10),
+			faceIndex: 1,
+			gid:       5,
+			expected:  284223755780101,
+		},
+		{
+			name:      maxPPem.String() + " ppem faceIdx " + strconv.Itoa(math.MaxUint16) + " GID " + fmt.Sprintf("%d", int64(math.MaxUint32)),
+			ppem:      maxPPem,
+			faceIndex: math.MaxUint16,
+			gid:       math.MaxUint32,
+			expected:  18446744073709551615,
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			actual := newGlyphID(tc.ppem, tc.faceIndex, tc.gid)
+			if actual != tc.expected {
+				t.Errorf("expected %d, got %d", tc.expected, actual)
+			}
+			actualPPEM, actualFaceIdx, actualGID := splitGlyphID(actual)
+			if actualPPEM != tc.ppem {
+				t.Errorf("expected ppem %d, got %d", tc.ppem, actualPPEM)
+			}
+			if actualFaceIdx != tc.faceIndex {
+				t.Errorf("expected faceIdx %d, got %d", tc.faceIndex, actualFaceIdx)
+			}
+			if actualGID != tc.gid {
+				t.Errorf("expected gid %d, got %d", tc.gid, actualGID)
+			}
+		})
+	}
+}

@@ 4,7 4,6 @@ package text
 
 import (
 	"bufio"
-	"fmt"
 	"io"
 	"strings"
 	"unicode/utf8"


@@ 471,7 470,6 @@ const (
 // newGlyphID encodes a face and a glyph id into a GlyphID.
 func newGlyphID(ppem fixed.Int26_6, faceIdx int, gid font.GID) GlyphID {
 	if gid&^((1<<gidbits)-1) != 0 {
-		fmt.Println(gid)
 		panic("glyph id out of bounds")
 	}
 	if faceIdx&^((1<<facebits)-1) != 0 {


@@ 488,7 486,7 @@ func newGlyphID(ppem fixed.Int26_6, faceIdx int, gid font.GID) GlyphID {
 
 // splitGlyphID is the opposite of newGlyphID.
 func splitGlyphID(g GlyphID) (fixed.Int26_6, int, font.GID) {
-	faceIdx := int(g) >> (gidbits + sizebits)
+	faceIdx := int(uint64(g) >> (gidbits + sizebits))
 	ppem := fixed.Int26_6((g & ((1<<sizebits - 1) << gidbits)) >> gidbits)
 	gid := font.GID(g) & (1<<gidbits - 1)
 	return ppem, faceIdx, gid