Add ability to encode raw byte slices as Typst images

README.md

@@ -22,7 +22,8 @@ Use at your own discretion for production systems.
 
 - PDF, SVG and PNG generation.
 - All Typst parameters are discoverable and documented in [cli-options.go](cli-options.go).
-- Go-to-Typst Value Encoder: Seamlessly inject any Go values (Including `image.Image` with a [wrapper](image.go)) into Typst documents via the provided encoder.
+- Go-to-Typst Value Encoder: Seamlessly inject any Go values.
+- Encode and inject images as a Typst markup simply by [wrapping](image.go) `image.Image` types or byte slices with raw JPEG or PNG data.
 - Errors from Typst CLI are returned as structured Go error objects with detailed information, such as line numbers and file paths.
 - Uses stdio; No temporary files will be created.
 - Good unit test coverage.

image.go

@@ -15,7 +15,10 @@ import (
 
 // Image can be used to encode any image.Image into a Typst image.
 //
-// For this, just wrap any image.Image with this type before passing it to MarshalValue or a ValueEncoder.
+// For this, just wrap any image.Image with this type before passing it to MarshalValue or a ValueEncoder:
+//
+//	typstImage := typst.Image{img}
+//	typst.InjectValues(&r, map[string]any{"TestImage": typstImage})
 type Image struct{ image.Image }
 
 func (i Image) MarshalTypstValue() ([]byte, error) {
@@ -38,3 +41,23 @@ func (i Image) MarshalTypstValue() ([]byte, error) {
 
 	return buf.Bytes(), nil
 }
+
+// ImageRaw can be used to pass the raw data of any image to Typst.
+// This will pass the raw byte values of a PNG, JPEG or any other image format that is supported by Typst.
+//
+// For this, just wrap any byte slice with this type before passing it to MarshalValue or a ValueEncoder:
+//
+//	typstImage := typst.ImageRaw(bufferPNG)
+//	typst.InjectValues(&r, map[string]any{"TestImage": typstImage})
+type ImageRaw []byte
+
+func (i ImageRaw) MarshalTypstValue() ([]byte, error) {
+	var buf bytes.Buffer
+	buf.WriteString("image.decode(bytes((") // TODO: Pass bytes directly to image once Typst 0.12.0 is not supported anymore
+	for _, b := range i {
+		buf.WriteString(strconv.FormatUint(uint64(b), 10) + ",")
+	}
+	buf.WriteString(")))")
+
+	return buf.Bytes(), nil
+}

image_test.go

@@ -7,6 +7,7 @@ package typst_test
 
 import (
 	"bytes"
+	_ "embed"
 	"image"
 	"image/color"
 	"io"
@@ -61,3 +62,29 @@ func TestImage(t *testing.T) {
 		t.Fatalf("Failed to compile document: %v.", err)
 	}
 }
+
+//go:embed test-files/test.png
+var testPNG []byte
+
+func TestImageRaw(t *testing.T) {
+	// Wrap image.
+	typstImage := typst.ImageRaw(testPNG)
+
+	cli := typst.CLI{}
+
+	var r bytes.Buffer
+
+	if err := typst.InjectValues(&r, map[string]any{"TestImage": typstImage}); err != nil {
+		t.Fatalf("Failed to inject values into Typst markup: %v.", err)
+	}
+
+	r.WriteString(`= Image test
+
+#TestImage
+
+#assert(type(TestImage) == content, message: "TestImage is not of expected type: got " + str(type(TestImage)) + ", want content")`) // TODO: Add another assertion for the image width and height as soon as it's possible to query that
+
+	if err := cli.Compile(&r, io.Discard, nil); err != nil {
+		t.Fatalf("Failed to compile document: %v.", err)
+	}
+}