imageresizer

README

Image resizer

Created as part of inspishop e-commerce platform by inspirum team.

On-demand image resizing, format converting and size optimization with the best CLI tools. Prepared to be used as Docker image with cloud storage as Amazon S3.

• image resizing, format converting and optimization
• support for jpeg, png, webp, bmp, gif, tiff, svg image formats
• file-cache for resized images on local disk (temporary cache) and cloud storage (persistent cache)

Usage example

Resizing

Application handle route with dynamic template (parameters divided by dash) and filepath parameters.

GET /image/{template}/{filepath}

Template

Options for resizing are specified as a dash delimited list of parameters, which can be supplied in any order. Duplicate parameters overwrite last values.

Name	Template	Example	Description
width	w[X]	w200	Resize to 200px width with proportional height
height	h[X]	h100	Resize to 100px height with proportional width
ratio	[X]x[X]	1x2	Resize to ratio to 1:2 (width : height)
crop	crop	crop	Image fill whole canvas (no addition background added)
upscale	upscale	upscale	Image can be larger than original

There are special template string original. This will return optimized image with original dimensions. It is helpful to show image with maximal resolution without knowing its dimension.

When there are set both height and width then ratio parameter will be ignored.

If output image has a different ratio than an original, image will be centered on transparent canvas (jpg has white background because it doesn't support transparent color).

Examples

Values are for an image with dimension 200x400px (width : height).

Template string	Output dimension
original	200x400
h100	50x100
w100	100x200
w50-w200	100x200
w100-h300	100x300
w200-1x1	200x200
w200-1x3	200x600
w100-h300-2x1	100x300
w1000-1x1	1000x1000
w1000-1x1-crop	200x200
w1000-1x1-crop-upscale	1000x1000

Width & height

Examples use jpg format because canvas background is white (for better visibility)

h200	w200	w188-h233
(300x200)	(200x134)	(188x233)

Ratio

h200-1x1	h200-1x2	h200-2x1
(200x200)	(100x200)	(400x200)

Crop

crop parameter will crop image to fill whole canvas

h200-1x1-crop	h200-1x2-crop	h200-2x1-crop
(200x200)	(100x200)	(400x200)

Upscale

By default, image can't up-size (be larger than original)

original	w250-h300	w250-h300-upscale	w250-h300-crop	w250-h300-crop-upscale
(200x200)	(250x300)	(250x300)	(167x200)	(250x300)

original	w500-h300-crop	w500-h300-crop	w500-h300-crop-upscale
(200x200)	(500x300)	(200x120)	(500x300)

Format encoding

Image can be encoded to any supported format simple by changing file extension in URL.

Original image extension is specified in original query parameter.

This is typically used to encode image as web-friendly webp format

http://localhost:3000/image/custom-w400-1x1-upscale/data/products/0/1/background.webp?original=png

Optimization

The package will use these optimizers if they are present on your system:

• pngquant 2
• jpegoptim
• gifsicle
• svgcleaner
• cwebp

By setting environment variable you can change default path to binary file or default arguments.

Environment variable	Default value
CMD_OPTIMIZER_PNG	pngquant --force --ext .png --skip-if-larger --quality 0-75 --speed 4 --strip --
CMD_OPTIMIZER_JPG	jpegoptim --force --strip-all --max 75 --quiet --all-progressive
CMD_OPTIMIZER_GIF	gifsicle --batch --optimize=3
CMD_OPTIMIZER_SVG	svgcleaner
CMD_OPTIMIZER_WEBP	cwebp -m 6 -pass 10 -mt -q 75 -quiet

Examples

64 kB	28 kB (43 %)	22 kB (34 %)

421 kB	91 kB (21 %)	23 kB (5 %)

System requirements

Installation

Testing

Contributing

Please see CONTRIBUTING and CODE_OF_CONDUCT for details.

Security

If you discover any security related issues, please email tomas.novotny@inspirum.cz instead of using the issue tracker.

Credits

• Tomáš Novotný
• All Contributors

License

The MIT License (MIT). Please see License File for more information.

Documentation

Index

• func ConvertFile(inputFilePath string, inputWidth int, inputHeight int, outputFilePath string, ...) (err error)
• func CopyFile(src, dst string) (err error)
• func CreateTempFileFromReader(c io.Reader, ext string) (f *os.File, err error)
• func GetEnv(key string, fallback string) string
• func GetEnvAsBool(key string, fallback bool) bool
• func GetEnvAsInt(key string, fallback int) int
• func GetImageDimensions(p string) (w int, h int, err error)
• func GetReaderContentType(c io.ReadSeeker) (mime string, err error)
• func NewS3Client(endpoint string, bucket string, key string, secret string, region string) *s3client
• func OpenFileWithModTime(p string) (*os.File, *time.Time, error)
• func OptimizeFile(filePath string) (err error)
• func ReplacePathExt(p string, r *http.Request) string
• func ShouldNotResize(template string, filePath string) bool
• func ValidateFilename(filePath string) error
• func ValidateTemplate(template string) error
• func WriteFileFromReader(p string, c io.Reader) (bool, error)
• type HttpError
• type Storage
• type Template
  • func NewTemplate(template string) *Template

Functions

func ConvertFile

func ConvertFile(inputFilePath string, inputWidth int, inputHeight int, outputFilePath string, template *Template) (err error)

func CopyFile

func CopyFile(src, dst string) (err error)

func CreateTempFileFromReader

func CreateTempFileFromReader(c io.Reader, ext string) (f *os.File, err error)

func GetEnv

func GetEnv(key string, fallback string) string

func GetEnvAsBool

func GetEnvAsBool(key string, fallback bool) bool

func GetEnvAsInt

func GetEnvAsInt(key string, fallback int) int

func GetImageDimensions

func GetImageDimensions(p string) (w int, h int, err error)

func GetReaderContentType

func GetReaderContentType(c io.ReadSeeker) (mime string, err error)

func NewS3Client

func NewS3Client(endpoint string, bucket string, key string, secret string, region string) *s3client

func OpenFileWithModTime

func OpenFileWithModTime(p string) (*os.File, *time.Time, error)

func OptimizeFile

func OptimizeFile(filePath string) (err error)

func ReplacePathExt

func ReplacePathExt(p string, r *http.Request) string

func ShouldNotResize

func ShouldNotResize(template string, filePath string) bool

func ValidateFilename

func ValidateFilename(filePath string) error

func ValidateTemplate

func ValidateTemplate(template string) error

func WriteFileFromReader

func WriteFileFromReader(p string, c io.Reader) (bool, error)

Types

type HttpError

type HttpError struct {
	StatusCode int
	// contains filtered or unexported fields
}

type Storage

type Storage interface {
	DownloadFile(path string, outputPath string) (f *os.File, err error)
	DownloadFileWithModTime(path string, outputPath string) (f *os.File, t *time.Time, err error)
	UploadContentReaderIfNewer(path string, time time.Time, content io.ReadSeeker) (bool, error)
	UploadContentReader(path string, content io.ReadSeeker) error
}

type Template

type Template struct {
	// contains filtered or unexported fields
}

func NewTemplate

func NewTemplate(template string) *Template