feautre/exr added support for exr type

image.go

@@ -196,6 +196,12 @@ func (i *Image) Gamma(exponent float64) ([]byte, error) {
 	return i.Process(options)
 }
 
+// AddGamma returns the alpha added image buffer.
+func (i *Image) AddAlpha() ([]byte, error) {
+	options := Options{AddAlpha: true}
+	return i.Process(options)
+}
+
 // Process processes the image based on the given transformation options,
 // talking with libvips bindings accordingly and returning the resultant
 // image buffer.

options.go

@@ -246,6 +246,7 @@ type Options struct {
 	OutputICC      string
 	InputICC       string
 	Palette        bool
+	AddAlpha       bool
 	// Speed defines the AVIF encoders CPU effort. Valid values are:
 	// 0-8 for AVIF encoding.
 	// 0-9 for PNG encoding.

resizer.go

@@ -154,6 +154,12 @@ func resizer(buf []byte, o Options) ([]byte, error) {
 		return nil, err
 	}
 
+	// Add Alpha, if necessary
+	image, err = addAlpha(image, o)
+	if err != nil {
+		return nil, err
+	}
+
 	return saveImage(image, o)
 }
 
@@ -437,6 +443,17 @@ func applyGamma(image *C.VipsImage, o Options) (*C.VipsImage, error) {
 	return image, nil
 }
 
+func addAlpha(image *C.VipsImage, o Options) (*C.VipsImage, error) {
+	var err error
+	if o.AddAlpha {
+		image, err = vipsAddAlpha(image, 255.0)
+		if err != nil {
+			return nil, err
+		}
+	}
+	return image, nil
+}
+
 func zoomImage(image *C.VipsImage, zoom int) (*C.VipsImage, error) {
 	if zoom == 0 {
 		return image, nil

type.go

@@ -32,6 +32,8 @@ const (
 	HEIF
 	// AVIF represents the AVIF image type.
 	AVIF
+	// EXR represents the EXR image type.
+	EXR
 )
 
 var (
@@ -51,6 +53,7 @@ var ImageTypes = map[ImageType]string{
 	MAGICK: "magick",
 	HEIF:   "heif",
 	AVIF:   "avif",
+	EXR:    "exr",
 }
 
 // imageMutex is used to provide thread-safe synchronization

type_test.go

@@ -23,6 +23,7 @@ func TestDeterminateImageType(t *testing.T) {
 		{"test2.heic", HEIF},
 		{"test3.heic", HEIF},
 		{"test.avif", AVIF},
+		{"test.exr", EXR},
 	}
 
 	for _, file := range files {
@@ -53,6 +54,7 @@ func TestDeterminateImageTypeName(t *testing.T) {
 		// {"test.jp2", "magick"},
 		{"test.heic", "heif"},
 		{"test.avif", "avif"},
+		{"test.exr", "exr"},
 	}
 
 	for _, file := range files {
@@ -106,6 +108,7 @@ func TestIsTypeNameSupported(t *testing.T) {
 		{"pdf", true},
 		{"heif", true},
 		{"avif", true},
+		{"exr", true},
 	}
 
 	for _, n := range types {

vips.go

@@ -205,6 +205,9 @@ func VipsIsTypeSupported(t ImageType) bool {
 	if t == AVIF {
 		return int(C.vips_type_find_bridge(C.HEIF)) != 0
 	}
+	if t == EXR {
+		return int(C.vips_type_find_bridge(C.MAGICK)) != 0
+	}
 	return false
 }
 
@@ -767,6 +770,10 @@ func vipsImageType(buf []byte) ImageType {
 		buf[8] == 0x61 && buf[9] == 0x76 && buf[10] == 0x69 && buf[11] == 0x66 {
 		return AVIF
 	}
+	if IsTypeSupported(EXR) && buf[0] == 0x76 && buf[1] == 0x2f &&
+		buf[2] == 0x31 && buf[3] == 0x01 {
+		return EXR
+	}
 
 	return UNKNOWN
 }
@@ -818,6 +825,17 @@ func max(x int) int {
 	return int(math.Max(float64(x), 0))
 }
 
+func vipsAddAlpha(image *C.VipsImage, alpha float64) (*C.VipsImage, error) {
+	var out *C.VipsImage
+	defer C.g_object_unref(C.gpointer(image))
+
+	err := C.vips_add_band(image, &out, C.double(alpha))
+	if err != 0 {
+		return nil, catchVipsError()
+	}
+	return out, nil
+}
+
 func vipsDrawWatermark(image *C.VipsImage, o WatermarkImage) (*C.VipsImage, error) {
 	var out *C.VipsImage