imagine

Usage

This application is configured via the environment. The following environment variables can be used:

$ imagine -h

KEY                       TYPE                                            DEFAULT                           REQUIRED    DESCRIPTION
IMAGINE_AWSREGION         String                                          eu-central-1                      true        AWS Region
IMAGINE_S3BUCKET          String                                                                            true        Name of the S3 Bucket w/o s3://
IMAGINE_S3PREFIX          String                                          imagine/                                      key prefix, leave empty to use bucket root
IMAGINE_CONTEXTPATH       String                                                                                        optional context path for http server
IMAGINE_PRESIGNEXPIRY     Duration                                        30m                                           how long presign urls are valid
IMAGINE_DUMPDIR           String                                          ./upload                                      temporary local upload directory
IMAGINE_FILEPARAM         String                                          uploadfile                                    name of param in multipart request
IMAGINE_PORT              Integer                                         8090                                          server httpo port
IMAGINE_QUEUE_SIZE        Integer                                         10                                            maxlen of s3 upload queue
IMAGINE_RESIZE_QUALITY    Integer                                         80                                            JPEG quality for resize
IMAGINE_RESIZE_MODES      Comma-separated list of String:Integer pairs    small:150,medium:300,large:600                map modes with width
IMAGINE_TIMEOUT           Duration                                        30s                                           http server timeouts
IMAGINE_DEBUG             True or False                                   false                                         debug mode for more verbose output

Resources

• Riding the wave. home Writing worker queues, in Go
• JOB QUEUES IN GO
• Singleton pattern in go
• A simple function to generate s3 presigned url in Go
• aws-doc-sdk-examples
• EXIF tags Wikipedia
• Best Practices for Designing a Pragmatic RESTful API
• Katacode makefile for golang
• An Introduction to Testing in Go

Tüdü

• temporary redirect api using presigned URLs ✅
• delete dumpfile if successfully uploaded to s3 ✅
• return header info along with iten list
• create preview and thumbs if type is image ✅

Run

go mod init github.com/tillkuhn/angkor/tools/imaging
go get -u github.com/aws/aws-sdk-go/...
go get -u github.com/rwcarlsen/goexif/...
go get -u github.com/disintegration/imaging/... 
go: downloading github.com/aws/aws-sdk-go v1.35.14
go run main.go

Do nice things with imaging

// Crop the original image to 300x300px size using the center anchor.
src = imaging.CropAnchor(src, 300, 300, imaging.Center)

// Resize the cropped image to width = 200px preserving the aspect ratio.
src = imaging.Resize(src, 200, 0, imaging.Lanczos)

// Create a blurred version of the image.
img1 := imaging.Blur(src, 5)

// Create a grayscale version of the image with higher contrast and sharpness.
img2 := imaging.Grayscale(src)
img2 = imaging.AdjustContrast(img2, 20)
img2 = imaging.Sharpen(img2, 2)

// Create an inverted version of the image.
img3 := imaging.Invert(src)

// Create an embossed version of the image using a convolution filter.
img4 := imaging.Convolve3x3(
    src,
    [9]float64{
        -1, -1, 0,
        -1, 1, 1,
        0, 1, 1,
    },
    nil,
)

// Create a new image and paste the four produced images into it.
dst := imaging.New(400, 400, color.NRGBA{0, 0, 0, 0})
dst = imaging.Paste(dst, img1, image.Pt(0, 0))
dst = imaging.Paste(dst, img2, image.Pt(0, 200))
dst = imaging.Paste(dst, img3, image.Pt(200, 0))
dst = imaging.Paste(dst, img4, image.Pt(200, 200))