Add custom font support to images.Text

Fixes #9253

resources/images/filters.go

@@ -15,7 +15,11 @@
 package images
 
 import (
+	"fmt"
+
+	"github.com/gohugoio/hugo/common/hugio"
 	"github.com/gohugoio/hugo/common/maps"
+	"github.com/gohugoio/hugo/resources/resource"
 
 	"github.com/disintegration/gift"
 	"github.com/spf13/cast"
@@ -61,6 +65,21 @@ func (*Filters) Text(text string, options ...interface{}) gift.Filter {
 				tf.y = cast.ToInt(v)
 			case "linespacing":
 				tf.linespacing = cast.ToInt(v)
+			case "font":
+				fontSource, ok1 := v.(hugio.ReadSeekCloserProvider)
+				identifier, ok2 := v.(resource.Identifier)
+
+				if !(ok1 && ok2) {
+					panic(fmt.Sprintf("invalid text font source: %T", v))
+				}
+
+				tf.fontSource = fontSource
+
+				// The input value isn't hashable and will not make a stable key.
+				// Replace it with a string in the map used as basis for the
+				// hash string.
+				opt["font"] = identifier.Key()
+
 			}
 		}
 	}

resources/images/text.go

@@ -16,9 +16,11 @@ package images
 import (
 	"image"
 	"image/draw"
+	"io"
 	"strings"
 
 	"github.com/disintegration/gift"
+	"github.com/gohugoio/hugo/common/hugio"
 
 	"golang.org/x/image/font"
 	"golang.org/x/image/font/gofont/goregular"
@@ -33,6 +35,7 @@ type textFilter struct {
 	x, y        int
 	size        float64
 	linespacing int
+	fontSource  hugio.ReadSeekCloserProvider
 }
 
 func (f textFilter) Draw(dst draw.Image, src image.Image, options *gift.Options) {
@@ -43,6 +46,17 @@ func (f textFilter) Draw(dst draw.Image, src image.Image, options *gift.Options)
 
 	// Load and parse font
 	ttf := goregular.TTF
+	if f.fontSource != nil {
+		rs, err := f.fontSource.ReadSeekCloser()
+		if err != nil {
+			panic(err)
+		}
+		defer rs.Close()
+		ttf, err = io.ReadAll(rs)
+		if err != nil {
+			panic(err)
+		}
+	}
 	otf, err := opentype.Parse(ttf)
 	if err != nil {
 		panic(err)