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// 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)
}
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