initial commit

examples/README.md

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+Example Codes and Images
+========================
+
+- [decode/decode.go](./decode/decode.go) -- a example code to decoding WebP image into image.RGBA.
+- [encode/encode.go](./encode/encode.go) -- a example code to encoding and writing image.RGBA into WebP file.

examples/decode/decode.go

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+package main
+
+import (
+	"github.com/harukasan/go-libwebp/examples/util"
+	"github.com/harukasan/go-libwebp/webp"
+)
+
+func main() {
+	var err error
+
+	// Read binary data
+	data := util.ReadFile("cosmos.webp")
+
+	// Decode
+	options := &webp.DecoderOptions{}
+	img, err := webp.DecodeRGBA(data, options)
+	if err != nil {
+		panic(err)
+	}
+
+	util.WritePNG(img, "encoded_cosmos.png")
+}

examples/encode/encode.go

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+package main
+
+import (
+	"bufio"
+	"image"
+
+	"github.com/harukasan/go-libwebp/examples/util"
+	"github.com/harukasan/go-libwebp/webp"
+)
+
+func main() {
+	img := util.ReadPNG("cosmos.png")
+
+	// Create file and buffered writer
+	io := util.CreateFile("encoded_cosmos.webp")
+	w := bufio.NewWriter(io)
+	defer func() {
+		w.Flush()
+		io.Close()
+	}()
+
+	config := webp.Config{
+		Preset:  webp.PresetDefault,
+		Quality: 90,
+		Method:  6,
+	}
+
+	// Encode into WebP
+	if err := webp.EncodeRGBA(w, img.(*image.RGBA), config); err != nil {
+		panic(err)
+	}
+}

examples/images/README.md

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+Example Images
+==============
+
+This directory contains example WebP encoded files and PNG source files.
+
+## Image Credits
+
+### Photos by Author
+
+These images are taken by author.
+These photos are licensed under the Creative Commons Attribution 3.0.
+You can also use these images under the same as [go-libwebp's license](../LICENSE).
+
+#### cosmos.png
+
+The cosmos taken in Nokono-shima (Nokono Island), Fukuoka, JAPAN.
+
+![cosmos.png](cosmos.png)
+
+WebP file is generated by following command:
+
+```sh
+$ cwebp -q 90 cosmos.png -o cosmos.webp
+Saving file 'cosmos.webp'
+File:      cosmos.png
+Dimension: 1024 x 768
+Output:    76954 bytes Y-U-V-All-PSNR 45.87 47.63 48.10   46.44 dB
+block count:  intra4: 2972
+intra16: 100  (-> 3.26%)
+skipped block: 1 (0.03%)
+bytes used:  header:            249  (0.3%)
+mode-partition:  15161  (19.7%)
+Residuals bytes  |segment 1|segment 2|segment 3|segment 4|  total
+macroblocks:     |       0%|      11%|      33%|      54%|    3072
+quantizer:       |      12 |      11 |       9 |       8 |
+filter level:    |       4 |       2 |       2 |       4 |
+```
+
+#### butterfly.png
+
+The butterfly taken in Ishigaki-jima (Ishigaki Island) in Okinawa, JAPAN.
+
+![butterfly.png](butterfly.png)
+
+WebP file is generated by following command:
+
+```sh
+$ cwebp -q 90 butterfly.png -o butterfly.webp
+Saving file 'butterfly.webp'
+File:      butterfly.png
+Dimension: 1024 x 768
+Output:    79198 bytes Y-U-V-All-PSNR 45.50 48.71 49.90   46.44 dB
+block count:  intra4: 2775
+intra16: 297  (-> 9.67%)
+skipped block: 0 (0.00%)
+bytes used:  header:            383  (0.5%)
+mode-partition:  13227  (16.7%)
+Residuals bytes  |segment 1|segment 2|segment 3|segment 4|  total
+macroblocks:     |       1%|       7%|      14%|      75%|    3072
+quantizer:       |      12 |      12 |      10 |       8 |
+filter level:    |       4 |       3 |       2 |       6 |
+```
+
+#### kinkaku.png
+
+Kinkaku taken in Kyoto, JAPAN.
+
+![kinkaku.png](kinkaku.png)
+
+WebP file is generated by following command:
+
+```sh
+$ cwebp -q 90 kinkaku.png -o kinkaku.webp
+Saving file 'kinkaku.webp'
+File:      kinkaku.png
+Dimension: 1024 x 768
+Output:    186300 bytes Y-U-V-All-PSNR 43.86 47.25 48.26   44.81 dB
+block count:  intra4: 2775
+intra16: 297  (-> 9.67%)
+skipped block: 243 (7.91%)
+bytes used:  header:            425  (0.2%)
+mode-partition:  16737  (9.0%)
+Residuals bytes  |segment 1|segment 2|segment 3|segment 4|  total
+macroblocks:     |       2%|      28%|      40%|      28%|    3072
+quantizer:       |      12 |      11 |       9 |       6 |
+filter level:    |       4 |       2 |       2 |       1 |
+```
+
+### From Google WebP Gallery
+
+These images picked up from [WebP Gallery](https://developers.google.com/speed/webp/gallery) in Google Developers.
+
+#### yellow-rose-3.png
+
+"Free Stock Photo in High Resolution - Yellow Rose 3 - Flowers" by Jon Sullivan
+
+This image is clipped by Google and licensed under [Creative Commons Attribution 3.0](https://creativecommons.org/licenses/by/3.0/). The Source of this image is in the public domain.
+
+<div style="background:url('./checkerboard.png')">
+<img title="yellow-rose-3.png" src="yellow-rose-3.png">
+</div>
+
+#### fizyplankton.png
+
+"baby tux for my user page" by Fizyplankton.
+
+This image file is in the public domain.
+
+<div style="background:url('./checkerboard.png')">
+<img title="fizyplankton.png" src="fizyplankton.png">
+</div>

examples/util/util.go

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+// Package util contains utility code for demosntration of go-libwebp.
+package util
+
+import (
+	"bufio"
+	"image"
+	"image/png"
+	"io"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+)
+
+// GetExFilePath returns the path of specified example file.
+func GetExFilePath(name string) string {
+	return filepath.Join(os.Getenv("GOPATH"), "src/github.com/harukasan/go-libwebp/examples/images", name)
+}
+
+// GetOutFilePath returns the path of specified out file.
+func GetOutFilePath(name string) string {
+	return filepath.Join(os.Getenv("GOPATH"), "src/github.com/harukasan/go-libwebp/examples/out", name)
+}
+
+// OpenFile opens specified example file
+func OpenFile(name string) (io io.Reader) {
+	io, err := os.Open(GetExFilePath(name))
+	if err != nil {
+		panic(err)
+	}
+	return
+}
+
+// ReadFile reads and returns data bytes of specified example file.
+func ReadFile(name string) (data []byte) {
+	data, err := ioutil.ReadFile(GetExFilePath(name))
+	if err != nil {
+		panic(err)
+	}
+	return
+}
+
+// CreateFile opens specified example file
+func CreateFile(name string) (f *os.File) {
+	f, err := os.Create(GetOutFilePath(name))
+	if err != nil {
+		panic(err)
+	}
+	return
+}
+
+// WritePNG encodes and writes image into PNG file.
+func WritePNG(img image.Image, name string) {
+	f, err := os.Create(GetOutFilePath(name))
+	if err != nil {
+		panic(err)
+	}
+	b := bufio.NewWriter(f)
+	defer func() {
+		b.Flush()
+		f.Close()
+	}()
+
+	if err := png.Encode(b, img); err != nil {
+		panic(err)
+	}
+	return
+}
+
+// ReadPNG reads and decodes png data into image.Image
+func ReadPNG(name string) (img image.Image) {
+	io, err := os.Open(GetExFilePath(name))
+	if err != nil {
+		panic(err)
+	}
+	img, err = png.Decode(io)
+	if err != nil {
+		panic(err)
+	}
+	return
+}