gomuks/vendor/github.com/disintegration/imaging/helpers.go

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2018-04-22 20:25:06 +02:00
package imaging
import (
"errors"
"image"
"image/color"
"image/draw"
"image/gif"
"image/jpeg"
"image/png"
"io"
"os"
"path/filepath"
"strings"
"golang.org/x/image/bmp"
"golang.org/x/image/tiff"
)
// Format is an image file format.
type Format int
// Image file formats.
const (
JPEG Format = iota
PNG
GIF
TIFF
BMP
)
func (f Format) String() string {
switch f {
case JPEG:
return "JPEG"
case PNG:
return "PNG"
case GIF:
return "GIF"
case TIFF:
return "TIFF"
case BMP:
return "BMP"
default:
return "Unsupported"
}
}
var (
// ErrUnsupportedFormat means the given image format (or file extension) is unsupported.
ErrUnsupportedFormat = errors.New("imaging: unsupported image format")
)
type fileSystem interface {
Create(string) (io.WriteCloser, error)
Open(string) (io.ReadCloser, error)
}
type localFS struct{}
func (localFS) Create(name string) (io.WriteCloser, error) { return os.Create(name) }
func (localFS) Open(name string) (io.ReadCloser, error) { return os.Open(name) }
var fs fileSystem = localFS{}
// Decode reads an image from r.
func Decode(r io.Reader) (image.Image, error) {
img, _, err := image.Decode(r)
return img, err
}
// Open loads an image from file
func Open(filename string) (image.Image, error) {
file, err := fs.Open(filename)
if err != nil {
return nil, err
}
defer file.Close()
return Decode(file)
}
type encodeConfig struct {
jpegQuality int
gifNumColors int
gifQuantizer draw.Quantizer
gifDrawer draw.Drawer
pngCompressionLevel png.CompressionLevel
}
var defaultEncodeConfig = encodeConfig{
jpegQuality: 95,
gifNumColors: 256,
gifQuantizer: nil,
gifDrawer: nil,
pngCompressionLevel: png.DefaultCompression,
}
// EncodeOption sets an optional parameter for the Encode and Save functions.
type EncodeOption func(*encodeConfig)
// JPEGQuality returns an EncodeOption that sets the output JPEG quality.
// Quality ranges from 1 to 100 inclusive, higher is better. Default is 95.
func JPEGQuality(quality int) EncodeOption {
return func(c *encodeConfig) {
c.jpegQuality = quality
}
}
// GIFNumColors returns an EncodeOption that sets the maximum number of colors
// used in the GIF-encoded image. It ranges from 1 to 256. Default is 256.
func GIFNumColors(numColors int) EncodeOption {
return func(c *encodeConfig) {
c.gifNumColors = numColors
}
}
// GIFQuantizer returns an EncodeOption that sets the quantizer that is used to produce
// a palette of the GIF-encoded image.
func GIFQuantizer(quantizer draw.Quantizer) EncodeOption {
return func(c *encodeConfig) {
c.gifQuantizer = quantizer
}
}
// GIFDrawer returns an EncodeOption that sets the drawer that is used to convert
// the source image to the desired palette of the GIF-encoded image.
func GIFDrawer(drawer draw.Drawer) EncodeOption {
return func(c *encodeConfig) {
c.gifDrawer = drawer
}
}
// PNGCompressionLevel returns an EncodeOption that sets the compression level
// of the PNG-encoded image. Default is png.DefaultCompression.
func PNGCompressionLevel(level png.CompressionLevel) EncodeOption {
return func(c *encodeConfig) {
c.pngCompressionLevel = level
}
}
// Encode writes the image img to w in the specified format (JPEG, PNG, GIF, TIFF or BMP).
func Encode(w io.Writer, img image.Image, format Format, opts ...EncodeOption) error {
cfg := defaultEncodeConfig
for _, option := range opts {
option(&cfg)
}
var err error
switch format {
case JPEG:
var rgba *image.RGBA
if nrgba, ok := img.(*image.NRGBA); ok {
if nrgba.Opaque() {
rgba = &image.RGBA{
Pix: nrgba.Pix,
Stride: nrgba.Stride,
Rect: nrgba.Rect,
}
}
}
if rgba != nil {
err = jpeg.Encode(w, rgba, &jpeg.Options{Quality: cfg.jpegQuality})
} else {
err = jpeg.Encode(w, img, &jpeg.Options{Quality: cfg.jpegQuality})
}
case PNG:
enc := png.Encoder{CompressionLevel: cfg.pngCompressionLevel}
err = enc.Encode(w, img)
case GIF:
err = gif.Encode(w, img, &gif.Options{
NumColors: cfg.gifNumColors,
Quantizer: cfg.gifQuantizer,
Drawer: cfg.gifDrawer,
})
case TIFF:
err = tiff.Encode(w, img, &tiff.Options{Compression: tiff.Deflate, Predictor: true})
case BMP:
err = bmp.Encode(w, img)
default:
err = ErrUnsupportedFormat
}
return err
}
// Save saves the image to file with the specified filename.
// The format is determined from the filename extension: "jpg" (or "jpeg"), "png", "gif", "tif" (or "tiff") and "bmp" are supported.
//
// Examples:
//
// // Save the image as PNG.
// err := imaging.Save(img, "out.png")
//
// // Save the image as JPEG with optional quality parameter set to 80.
// err := imaging.Save(img, "out.jpg", imaging.JPEGQuality(80))
//
func Save(img image.Image, filename string, opts ...EncodeOption) (err error) {
formats := map[string]Format{
".jpg": JPEG,
".jpeg": JPEG,
".png": PNG,
".tif": TIFF,
".tiff": TIFF,
".bmp": BMP,
".gif": GIF,
}
ext := strings.ToLower(filepath.Ext(filename))
f, ok := formats[ext]
if !ok {
return ErrUnsupportedFormat
}
file, err := fs.Create(filename)
if err != nil {
return err
}
defer func() {
cerr := file.Close()
if err == nil {
err = cerr
}
}()
return Encode(file, img, f, opts...)
}
// New creates a new image with the specified width and height, and fills it with the specified color.
func New(width, height int, fillColor color.Color) *image.NRGBA {
if width <= 0 || height <= 0 {
return &image.NRGBA{}
}
dst := image.NewNRGBA(image.Rect(0, 0, width, height))
c := color.NRGBAModel.Convert(fillColor).(color.NRGBA)
if c.R == 0 && c.G == 0 && c.B == 0 && c.A == 0 {
return dst
}
// Fill the first row.
i := 0
for x := 0; x < width; x++ {
dst.Pix[i+0] = c.R
dst.Pix[i+1] = c.G
dst.Pix[i+2] = c.B
dst.Pix[i+3] = c.A
i += 4
}
// Copy the first row to other rows.
size := width * 4
parallel(1, height, func(ys <-chan int) {
for y := range ys {
i = y * dst.Stride
copy(dst.Pix[i:i+size], dst.Pix[0:size])
}
})
return dst
}
// Clone returns a copy of the given image.
func Clone(img image.Image) *image.NRGBA {
src := newScanner(img)
dst := image.NewNRGBA(image.Rect(0, 0, src.w, src.h))
size := src.w * 4
parallel(0, src.h, func(ys <-chan int) {
for y := range ys {
i := y * dst.Stride
src.scan(0, y, src.w, y+1, dst.Pix[i:i+size])
}
})
return dst
}