Method calcDct2Hash

testutil/image_hash.go:179–209

calcDct2Hash calculates the DCT hash for the given image data buffer

(buf []byte)

// calcDct2Hash calculates the DCT hash for the given image data buffer
func (h *ImageHash) calcDct2Hash(buf []byte) error {
	bufPtr := unsafe.Pointer(unsafe.SliceData(buf))

	var dctArray *C.float
	var length C.size_t

	defer func() {
		if dctArray != nil {
			C.free(unsafe.Pointer(dctArray))
		}
	}()

	//nolint:gocritic
	result := C.vips_dct2_hash(bufPtr, C.size_t(len(buf)), &dctArray, &length)

	if result != 0 {
		return fmt.Errorf("failed to calculate DCT hash: %s", vipsErrorMessage())
	}

	dctHash := make([]float32, int(length))

	// Convert C array to Go slice safely
	cSlice := unsafe.Slice(dctArray, int(length))
	for i, v := range cSlice {
		dctHash[i] = float32(v)
	}

	h.dctHash = dctHash

	return nil
}

// dumpDctHash writes the DCT hash to a writer
func (h *ImageHash) dumpDctHash(w io.Writer) error {