1 files changed, 86 insertions, 0 deletions
diff --git a/go/zopflipng/zopflipng.go b/go/zopflipng/zopflipng.go
new file mode 100644
index 0000000..f532321
--- /dev/null
+++ b/go/zopflipng/zopflipng.go
@@ -0,0 +1,86 @@
+// Copyright 2019 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+package zopflipng
+
+import (
+	"fmt"
+)
+
+/*
+#cgo LDFLAGS: -lzopflipng -lzopfli -lstdc++ -lm
+#include <stdlib.h>
+#include <string.h>
+#include "zopflipng_lib.h"
+*/
+import "C"
+import "unsafe"
+
+// Options allows overriding of some internal parameters.
+type Options struct {
+	LossyTransparent   bool
+	Lossy8bit          bool
+	NumIterations      int
+	NumIterationsLarge int
+}
+
+// NewOptions creates an options struct with the default parameters.
+func NewOptions() *Options {
+	ret := &Options{
+		LossyTransparent:   false,
+		Lossy8bit:          false,
+		NumIterations:      15,
+		NumIterationsLarge: 5,
+	}
+	return ret
+}
+
+// Compress recompresses a PNG using Zopfli.
+func Compress(inputSlice []byte) ([]byte, error) {
+	return CompressWithOptions(inputSlice, NewOptions())
+}
+
+// CompressWithOptions allows overriding some internal parameters.
+func CompressWithOptions(inputSlice []byte, options *Options) ([]byte, error) {
+	cOptions := createCOptions(options)
+	input := (*C.uchar)(unsafe.Pointer(&inputSlice[0]))
+	inputSize := (C.size_t)(len(inputSlice))
+	var compressed *C.uchar
+	var compressedLength C.size_t
+	errCode := int(C.CZopfliPNGOptimize(input, inputSize, &cOptions, 0, &compressed, &compressedLength))
+	defer C.free(unsafe.Pointer(compressed))
+	if errCode != 0 {
+		return nil, fmt.Errorf("ZopfliPng failed with code: %d", errCode)
+	}
+
+	result := make([]byte, compressedLength)
+	C.memmove(unsafe.Pointer(&result[0]), unsafe.Pointer(compressed), compressedLength)
+	return result, nil
+}
+
+func createCOptions(options *Options) C.struct_CZopfliPNGOptions {
+	var cOptions C.struct_CZopfliPNGOptions
+	C.CZopfliPNGSetDefaults(&cOptions)
+	cOptions.lossy_transparent = boolToInt(options.LossyTransparent)
+	cOptions.lossy_8bit = boolToInt(options.Lossy8bit)
+	cOptions.num_iterations = C.int(options.NumIterations)
+	cOptions.num_iterations_large = C.int(options.NumIterationsLarge)
+	return cOptions
+}
+
+func boolToInt(b bool) C.int {
+	if b {
+		return C.int(1)
+	}
+	return C.int(0)
+}