feat: image variants engine

2026-10-08 02:33:32 +02:00
1 parent f0845de643
commit f1d56ef50e
@@ -0,0 +1,60 @@
+package imaging
+
+import (
+	domain "RenewCMS/internal/domain/image"
+	"bytes"
+	"image"
+	"image/jpeg"
+	"image/png"
+
+	"github.com/gen2brain/webp"
+)
+
+type encoder interface {
+	contentType() string
+	flattensTransparency() bool
+	encode(output *bytes.Buffer, source image.Image, quality int) error
+}
+
+type jpegEncoder struct{}
+
+func (jpegEncoder) contentType() string { return "image/jpeg" }
+
+func (jpegEncoder) flattensTransparency() bool { return true }
+
+func (jpegEncoder) encode(output *bytes.Buffer, source image.Image, quality int) error {
+	return jpeg.Encode(output, source, &jpeg.Options{Quality: quality})
+}
+
+type pngEncoder struct{}
+
+func (pngEncoder) contentType() string { return "image/png" }
+
+func (pngEncoder) flattensTransparency() bool { return false }
+
+func (pngEncoder) encode(output *bytes.Buffer, source image.Image, _ int) error {
+	return png.Encode(output, source)
+}
+
+type webpEncoder struct{}
+
+func (webpEncoder) contentType() string { return "image/webp" }
+
+func (webpEncoder) flattensTransparency() bool { return false }
+
+func (webpEncoder) encode(output *bytes.Buffer, source image.Image, quality int) error {
+	return webp.Encode(output, source, webp.Options{Quality: quality})
+}
+
+var knownEncoders = map[domain.VariantFormat]encoder{
+	domain.FormatJPEG: jpegEncoder{},
+	domain.FormatPNG:  pngEncoder{},
+	domain.FormatWebP: webpEncoder{},
+}
+
+var sourceFormats = map[string]domain.VariantFormat{
+	"jpeg": domain.FormatJPEG,
+	"png":  domain.FormatPNG,
+	"webp": domain.FormatWebP,
+	"gif":  domain.FormatPNG,
+}
@@ -0,0 +1,89 @@
+package imaging
+
+import (
+	domain "RenewCMS/internal/domain/image"
+	"image"
+	"math"
+)
+
+type layout struct {
+	canvas  image.Point
+	source  image.Rectangle
+	content image.Rectangle
+}
+
+func layoutFor(source image.Point, settings domain.VariantSettings) layout {
+	if settings.Width == nil || settings.Height == nil {
+		return proportionalLayout(source, settings)
+	}
+	box := image.Pt(*settings.Width, *settings.Height)
+	switch settings.Fit {
+	case domain.FitContain:
+		return containLayout(source, box)
+	case domain.FitInside:
+		return insideLayout(source, box)
+	default:
+		return coverLayout(source, box)
+	}
+}
+
+func proportionalLayout(source image.Point, settings domain.VariantSettings) layout {
+	scale := 1.0
+	if settings.Width != nil {
+		scale = math.Min(scale, ratio(*settings.Width, source.X))
+	}
+	if settings.Height != nil {
+		scale = math.Min(scale, ratio(*settings.Height, source.Y))
+	}
+	return wholeSourceLayout(source, scaled(source, scale))
+}
+
+func insideLayout(source image.Point, box image.Point) layout {
+	scale := math.Min(1, math.Min(ratio(box.X, source.X), ratio(box.Y, source.Y)))
+	return wholeSourceLayout(source, scaled(source, scale))
+}
+
+func wholeSourceLayout(source image.Point, output image.Point) layout {
+	return layout{canvas: output, source: image.Rectangle{Max: source}, content: image.Rectangle{Max: output}}
+}
+
+func coverLayout(source image.Point, box image.Point) layout {
+	shrink := math.Min(1, math.Min(ratio(source.X, box.X), ratio(source.Y, box.Y)))
+	output := scaled(box, shrink)
+	return layout{canvas: output, source: centeredCrop(source, output), content: image.Rectangle{Max: output}}
+}
+
+func containLayout(source image.Point, box image.Point) layout {
+	fit := math.Min(1, math.Min(ratio(box.X, source.X), ratio(box.Y, source.Y)))
+	content := scaled(source, fit)
+	content = image.Pt(min(content.X, box.X), min(content.Y, box.Y))
+	origin := image.Pt((box.X-content.X)/2, (box.Y-content.Y)/2)
+	return layout{canvas: box, source: image.Rectangle{Max: source}, content: image.Rectangle{Min: origin, Max: origin.Add(content)}}
+}
+
+func centeredCrop(source image.Point, output image.Point) image.Rectangle {
+	crop := source
+	if source.X*output.Y >= source.Y*output.X {
+		crop.X = min(source.X, roundedDivision(source.Y*output.X, output.Y))
+	} else {
+		crop.Y = min(source.Y, roundedDivision(source.X*output.Y, output.X))
+	}
+	origin := image.Pt((source.X-crop.X)/2, (source.Y-crop.Y)/2)
+	return image.Rectangle{Min: origin, Max: origin.Add(crop)}
+}
+
+func ratio(numerator int, denominator int) float64 {
+	return float64(numerator) / float64(denominator)
+}
+
+func roundedDivision(numerator int, denominator int) int {
+	return int(math.Round(ratio(numerator, denominator)))
+}
+
+func scaled(size image.Point, factor float64) image.Point {
+	return image.Pt(scaledLength(size.X, factor), scaledLength(size.Y, factor))
+}
+
+func scaledLength(length int, factor float64) int {
+	return max(1, int(math.Round(float64(length)*factor)))
+}
@@ -0,0 +1,102 @@
+package imaging
+
+import (
+	domain "RenewCMS/internal/domain/image"
+	"bytes"
+	"image"
+	"image/color"
+	"io"
+	"slices"
+
+	xdraw "golang.org/x/image/draw"
+
+	_ "image/gif"
+	_ "image/jpeg"
+	_ "image/png"
+
+	_ "golang.org/x/image/webp"
+)
+
+type VariantRenderer struct {
+	encoders map[domain.VariantFormat]encoder
+}
+
+var _ domain.VariantRenderer = &VariantRenderer{}
+
+func NewVariantRenderer() *VariantRenderer {
+	return NewVariantRendererEncoding(domain.FormatOriginal, domain.FormatJPEG, domain.FormatPNG, domain.FormatWebP)
+}
+
+func NewVariantRendererEncoding(formats ...domain.VariantFormat) *VariantRenderer {
+	encoders := map[domain.VariantFormat]encoder{}
+	for format, candidate := range knownEncoders {
+		if slices.Contains(formats, format) {
+			encoders[format] = candidate
+		}
+	}
+	return &VariantRenderer{encoders}
+}
+
+func (r *VariantRenderer) EncodableFormats() []domain.VariantFormat {
+	formats := []domain.VariantFormat{domain.FormatOriginal}
+	for _, format := range domain.VariantFormats() {
+		if _, encodable := r.encoders[format]; encodable {
+			formats = append(formats, format)
+		}
+	}
+	return formats
+}
+
+func (r *VariantRenderer) DeclaredSize(source io.Reader) (int, int, error) {
+	header, _, err := image.DecodeConfig(source)
+	if err != nil {
+		return 0, 0, err
+	}
+	return header.Width, header.Height, nil
+}
+
+func (r *VariantRenderer) Render(source io.Reader, settings domain.VariantSettings) (domain.RenderedVariant, error) {
+	decoded, sourceFormat, err := image.Decode(source)
+	if err != nil {
+		return domain.RenderedVariant{}, err
+	}
+	chosen := r.encoderFor(settings.Format, sourceFormat)
+	arranged := arrange(decoded, layoutFor(decoded.Bounds().Size(), settings), chosen.flattensTransparency())
+
+	var output bytes.Buffer
+	if err := chosen.encode(&output, arranged, qualityOf(settings)); err != nil {
+		return domain.RenderedVariant{}, err
+	}
+	return domain.RenderedVariant{Content: output.Bytes(), ContentType: chosen.contentType()}, nil
+}
+
+func (r *VariantRenderer) encoderFor(format domain.VariantFormat, sourceFormat string) encoder {
+	if format == domain.FormatOriginal {
+		format = sourceFormats[sourceFormat]
+	}
+	if chosen, encodable := r.encoders[format]; encodable {
+		return chosen
+	}
+	return pngEncoder{}
+}
+
+func qualityOf(settings domain.VariantSettings) int {
+	if settings.Quality == nil {
+		return domain.DefaultVariantQuality
+	}
+	return *settings.Quality
+}
+
+func arrange(decoded image.Image, plan layout, onWhite bool) image.Image {
+	canvas := image.NewRGBA(image.Rectangle{Max: plan.canvas})
+	if onWhite {
+		xdraw.Draw(canvas, canvas.Bounds(), image.NewUniform(color.White), image.Point{}, xdraw.Src)
+	}
+	sourceRegion := plan.source.Add(decoded.Bounds().Min)
+	if plan.source.Size() == plan.content.Size() {
+		xdraw.Draw(canvas, plan.content, decoded, sourceRegion.Min, xdraw.Over)
+		return canvas
+	}
+	xdraw.CatmullRom.Scale(canvas, plan.content, decoded, sourceRegion, xdraw.Over, nil)
+	return canvas
+}