108 lines
2.6 KiB
Go
108 lines
2.6 KiB
Go
// Package collage makes a pic collage
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package collage
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import (
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"errors"
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"image"
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"image/color"
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"image/draw"
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"image/jpeg"
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"io"
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"io/fs"
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"go.oneofone.dev/resize"
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)
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type Dimension struct {
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Width uint `json:"width"`
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Height uint `json:"height"`
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}
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type Point struct {
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X uint `json:"x"`
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Y uint `json:"y"`
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}
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type Rectangle struct {
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Start Point `json:"start"`
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End Point `json:"end"`
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}
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func (r Rectangle) ToImgRect() image.Rectangle {
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return image.Rectangle{
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Min: image.Point{int(r.Start.X), int(r.Start.Y)},
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Max: image.Point{int(r.End.X), int(r.End.Y)},
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}
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}
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type Photo struct {
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ImageName string `json:"image"`
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Crop Rectangle `json:"crop"`
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Frame Rectangle `json:"frame"`
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}
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type Request struct {
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BackgroundImage string `json:"background_image"`
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Aspect Dimension `json:"aspect"`
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Dimension Dimension `json:"dimension"`
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Photos []Photo `json:"photos"`
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}
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func Make(req *Request, source fs.FS, output io.Writer) error {
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rec := image.Rect(0, 0, int(req.Aspect.Width), int(req.Aspect.Height))
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canvas := image.NewRGBA64(rec)
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white := color.RGBA{255, 255, 255, 255}
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draw.Draw(canvas, rec, &image.Uniform{white}, image.Point{}, draw.Src)
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for _, photo := range req.Photos {
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img, err := GetImage(source, photo.ImageName)
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if err != nil {
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return err
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}
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croppedImage, err := Crop(img, photo.Crop)
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if err != nil {
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return err
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}
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destRect := FrameTranslate(req.Aspect, req.Dimension, photo.Frame).ToImgRect()
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resizedImg := resize.Resize(uint(destRect.Dx()), uint(destRect.Dy()), croppedImage, resize.Lanczos3)
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draw.Draw(canvas, destRect, resizedImg, image.Point{0, 0}, draw.Src)
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}
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var opt jpeg.Options
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opt.Quality = 100
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return jpeg.Encode(output, canvas, &opt)
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}
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func FrameTranslate(resolution Dimension, frameSize Dimension, frame Rectangle) Rectangle {
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newX := func(oldX uint) uint {
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return oldX * resolution.Width / frameSize.Width
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}
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newY := func(oldY uint) uint {
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return oldY * resolution.Height / frameSize.Height
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}
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return Rectangle{
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Start: Point{newX(frame.Start.X), newY(frame.Start.Y)},
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End: Point{newX(frame.End.X), newY(frame.End.Y)},
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}
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}
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type HasSubImage interface {
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SubImage(r image.Rectangle) image.Image
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}
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func Crop(img image.Image, r Rectangle) (image.Image, error) {
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if imgHS, ok := img.(HasSubImage); ok {
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return imgHS.SubImage(r.ToImgRect()), nil
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}
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return nil, errors.New("image does not support cropping")
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}
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func GetImage(source fs.FS, imageName string) (image.Image, error) {
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imgF, err := source.Open(imageName)
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if err != nil {
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return nil, err
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}
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img, _, err := image.Decode(imgF)
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return img, err
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}
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