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Add pure Go image processor with resize and format conversion

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Implements the Processor interface using disintegration/imaging library.
Supports JPEG, PNG, GIF, WebP decoding and JPEG, PNG, GIF encoding.
Includes all fit modes: cover, contain, fill, inside, outside.
This commit is contained in:
Jeffrey Paul
2026-01-08 03:54:50 -08:00
parent 9629139989
commit 5462c9222c
4 changed files with 503 additions and 10 deletions
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6
go.mod
View File

@@ -5,12 +5,14 @@ go 1.25.4
require (
git.eeqj.de/sneak/smartconfig v1.0.0
github.com/99designs/basicauth-go v0.0.0-20230316000542-bf6f9cbbf0f8
github.com/disintegration/imaging v1.6.2
github.com/getsentry/sentry-go v0.40.0
github.com/go-chi/chi/v5 v5.2.3
github.com/go-chi/cors v1.2.2
github.com/prometheus/client_golang v1.23.2
github.com/slok/go-http-metrics v0.13.0
go.uber.org/fx v1.24.0
golang.org/x/image v0.34.0
modernc.org/sqlite v1.42.2
)
@@ -124,10 +126,10 @@ require (
golang.org/x/exp v0.0.0-20250620022241-b7579e27df2b // indirect
golang.org/x/net v0.43.0 // indirect
golang.org/x/oauth2 v0.30.0 // indirect
golang.org/x/sync v0.16.0 // indirect
golang.org/x/sync v0.19.0 // indirect
golang.org/x/sys v0.36.0 // indirect
golang.org/x/term v0.34.0 // indirect
golang.org/x/text v0.28.0 // indirect
golang.org/x/text v0.32.0 // indirect
golang.org/x/time v0.12.0 // indirect
google.golang.org/api v0.237.0 // indirect
google.golang.org/genproto v0.0.0-20250505200425-f936aa4a68b2 // indirect

21
go.sum
View File

@@ -92,6 +92,8 @@ github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc h1:U9qPSI2PIWSS1
github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f h1:lO4WD4F/rVNCu3HqELle0jiPLLBs70cWOduZpkS1E78=
github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f/go.mod h1:cuUVRXasLTGF7a8hSLbxyZXjz+1KgoB3wDUb6vlszIc=
github.com/disintegration/imaging v1.6.2 h1:w1LecBlG2Lnp8B3jk5zSuNqd7b4DXhcjwek1ei82L+c=
github.com/disintegration/imaging v1.6.2/go.mod h1:44/5580QXChDfwIclfc/PCwrr44amcmDAg8hxG0Ewe4=
github.com/dustin/go-humanize v1.0.1 h1:GzkhY7T5VNhEkwH0PVJgjz+fX1rhBrR7pRT3mDkpeCY=
github.com/dustin/go-humanize v1.0.1/go.mod h1:Mu1zIs6XwVuF/gI1OepvI0qD18qycQx+mFykh5fBlto=
github.com/emicklei/go-restful/v3 v3.12.1 h1:PJMDIM/ak7btuL8Ex0iYET9hxM3CI2sjZtzpL63nKAU=
@@ -420,10 +422,13 @@ golang.org/x/crypto v0.41.0 h1:WKYxWedPGCTVVl5+WHSSrOBT0O8lx32+zxmHxijgXp4=
golang.org/x/crypto v0.41.0/go.mod h1:pO5AFd7FA68rFak7rOAGVuygIISepHftHnr8dr6+sUc=
golang.org/x/exp v0.0.0-20250620022241-b7579e27df2b h1:M2rDM6z3Fhozi9O7NWsxAkg/yqS/lQJ6PmkyIV3YP+o=
golang.org/x/exp v0.0.0-20250620022241-b7579e27df2b/go.mod h1:3//PLf8L/X+8b4vuAfHzxeRUl04Adcb341+IGKfnqS8=
golang.org/x/image v0.0.0-20191009234506-e7c1f5e7dbb8/go.mod h1:FeLwcggjj3mMvU+oOTbSwawSJRM1uh48EjtB4UJZlP0=
golang.org/x/image v0.34.0 h1:33gCkyw9hmwbZJeZkct8XyR11yH889EQt/QH4VmXMn8=
golang.org/x/image v0.34.0/go.mod h1:2RNFBZRB+vnwwFil8GkMdRvrJOFd1AzdZI6vOY+eJVU=
golang.org/x/mod v0.2.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
golang.org/x/mod v0.3.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
golang.org/x/mod v0.27.0 h1:kb+q2PyFnEADO2IEF935ehFUXlWiNjJWtRNgBLSfbxQ=
golang.org/x/mod v0.27.0/go.mod h1:rWI627Fq0DEoudcK+MBkNkCe0EetEaDSwJJkCcjpazc=
golang.org/x/mod v0.30.0 h1:fDEXFVZ/fmCKProc/yAXXUijritrDzahmwwefnjoPFk=
golang.org/x/mod v0.30.0/go.mod h1:lAsf5O2EvJeSFMiBxXDki7sCgAxEUcZHXoXMKT4GJKc=
golang.org/x/net v0.0.0-20181114220301-adae6a3d119a/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
golang.org/x/net v0.0.0-20190613194153-d28f0bde5980/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
@@ -443,8 +448,8 @@ golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJ
golang.org/x/sync v0.0.0-20190911185100-cd5d95a43a6e/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
golang.org/x/sync v0.0.0-20201020160332-67f06af15bc9/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
golang.org/x/sync v0.0.0-20210220032951-036812b2e83c/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
golang.org/x/sync v0.16.0 h1:ycBJEhp9p4vXvUZNszeOq0kGTPghopOL8q0fq3vstxw=
golang.org/x/sync v0.16.0/go.mod h1:1dzgHSNfp02xaA81J2MS99Qcpr2w7fw1gpm99rleRqA=
golang.org/x/sync v0.19.0 h1:vV+1eWNmZ5geRlYjzm2adRgW2/mcpevXNg50YZtPCE4=
golang.org/x/sync v0.19.0/go.mod h1:9KTHXmSnoGruLpwFjVSX0lNNA75CykiMECbovNTZqGI=
golang.org/x/sys v0.0.0-20180823144017-11551d06cbcc/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
golang.org/x/sys v0.0.0-20180905080454-ebe1bf3edb33/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
golang.org/x/sys v0.0.0-20181116152217-5ac8a444bdc5/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
@@ -478,8 +483,8 @@ golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
golang.org/x/text v0.3.2/go.mod h1:bEr9sfX3Q8Zfm5fL9x+3itogRgK3+ptLWKqgva+5dAk=
golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
golang.org/x/text v0.28.0 h1:rhazDwis8INMIwQ4tpjLDzUhx6RlXqZNPEM0huQojng=
golang.org/x/text v0.28.0/go.mod h1:U8nCwOR8jO/marOQ0QbDiOngZVEBB7MAiitBuMjXiNU=
golang.org/x/text v0.32.0 h1:ZD01bjUt1FQ9WJ0ClOL5vxgxOI/sVCNgX1YtKwcY0mU=
golang.org/x/text v0.32.0/go.mod h1:o/rUWzghvpD5TXrTIBuJU77MTaN0ljMWE47kxGJQ7jY=
golang.org/x/time v0.12.0 h1:ScB/8o8olJvc+CQPWrK3fPZNfh7qgwCrY0zJmoEQLSE=
golang.org/x/time v0.12.0/go.mod h1:CDIdPxbZBQxdj6cxyCIdrNogrJKMJ7pr37NYpMcMDSg=
golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
@@ -487,8 +492,8 @@ golang.org/x/tools v0.0.0-20190907020128-2ca718005c18/go.mod h1:b+2E5dAYhXwXZwtn
golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
golang.org/x/tools v0.0.0-20200619180055-7c47624df98f/go.mod h1:EkVYQZoAsY45+roYkvgYkIh4xh/qjgUK9TdY2XT94GE=
golang.org/x/tools v0.0.0-20210106214847-113979e3529a/go.mod h1:emZCQorbCU4vsT4fOWvOPXz4eW1wZW4PmDk9uLelYpA=
golang.org/x/tools v0.36.0 h1:kWS0uv/zsvHEle1LbV5LE8QujrxB3wfQyxHfhOk0Qkg=
golang.org/x/tools v0.36.0/go.mod h1:WBDiHKJK8YgLHlcQPYQzNCkUxUypCaa5ZegCVutKm+s=
golang.org/x/tools v0.39.0 h1:ik4ho21kwuQln40uelmciQPp9SipgNDdrafrYA4TmQQ=
golang.org/x/tools v0.39.0/go.mod h1:JnefbkDPyD8UU2kI5fuf8ZX4/yUeh9W877ZeBONxUqQ=
golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

244
internal/imgcache/processor.go Normal file
View File

@@ -0,0 +1,244 @@
package imgcache
import (
"bytes"
"context"
"fmt"
"image"
"image/gif"
"image/jpeg"
"image/png"
"io"
"github.com/disintegration/imaging"
"golang.org/x/image/webp"
)
// ImageProcessor implements the Processor interface using pure Go libraries.
type ImageProcessor struct{}
// NewImageProcessor creates a new image processor.
func NewImageProcessor() *ImageProcessor {
return &ImageProcessor{}
}
// Process transforms an image according to the request.
func (p *ImageProcessor) Process(
_ context.Context,
input io.Reader,
req *ImageRequest,
) (*ProcessResult, error) {
// Read input
data, err := io.ReadAll(input)
if err != nil {
return nil, fmt.Errorf("failed to read input: %w", err)
}
// Decode image
img, format, err := p.decode(data)
if err != nil {
return nil, fmt.Errorf("failed to decode image: %w", err)
}
// Get original dimensions
bounds := img.Bounds()
origWidth := bounds.Dx()
origHeight := bounds.Dy()
// Determine target dimensions
targetWidth := req.Size.Width
targetHeight := req.Size.Height
// If both are 0, keep original size
if targetWidth == 0 && targetHeight == 0 {
targetWidth = origWidth
targetHeight = origHeight
}
// Resize if needed
if targetWidth != origWidth || targetHeight != origHeight {
img = p.resize(img, targetWidth, targetHeight, req.FitMode)
}
// Determine output format
outputFormat := req.Format
if outputFormat == FormatOriginal || outputFormat == "" {
outputFormat = p.formatFromString(format)
}
// Encode to target format
output, err := p.encode(img, outputFormat, req.Quality)
if err != nil {
return nil, fmt.Errorf("failed to encode: %w", err)
}
finalBounds := img.Bounds()
return &ProcessResult{
Content: io.NopCloser(bytes.NewReader(output)),
ContentLength: int64(len(output)),
ContentType: ImageFormatToMIME(outputFormat),
Width: finalBounds.Dx(),
Height: finalBounds.Dy(),
}, nil
}
// SupportedInputFormats returns MIME types this processor can read.
func (p *ImageProcessor) SupportedInputFormats() []string {
return []string{
string(MIMETypeJPEG),
string(MIMETypePNG),
string(MIMETypeGIF),
string(MIMETypeWebP),
}
}
// SupportedOutputFormats returns formats this processor can write.
func (p *ImageProcessor) SupportedOutputFormats() []ImageFormat {
return []ImageFormat{
FormatJPEG,
FormatPNG,
FormatGIF,
// WebP encoding not supported in pure Go, will fall back to PNG
}
}
// decode decodes image data into an image.Image.
func (p *ImageProcessor) decode(data []byte) (image.Image, string, error) {
r := bytes.NewReader(data)
// Try standard formats first
img, format, err := image.Decode(r)
if err == nil {
return img, format, nil
}
// Try WebP
r.Reset(data)
img, err = webp.Decode(r)
if err == nil {
return img, "webp", nil
}
return nil, "", fmt.Errorf("unsupported image format")
}
// resize resizes the image according to the fit mode.
func (p *ImageProcessor) resize(img image.Image, width, height int, fit FitMode) image.Image {
switch fit {
case FitCover:
// Resize and crop to fill exact dimensions
return imaging.Fill(img, width, height, imaging.Center, imaging.Lanczos)
case FitContain:
// Resize to fit within dimensions, maintaining aspect ratio
return imaging.Fit(img, width, height, imaging.Lanczos)
case FitFill:
// Resize to exact dimensions (may distort)
return imaging.Resize(img, width, height, imaging.Lanczos)
case FitInside:
// Same as contain, but only shrink
bounds := img.Bounds()
origW := bounds.Dx()
origH := bounds.Dy()
if origW <= width && origH <= height {
return img // Already fits
}
return imaging.Fit(img, width, height, imaging.Lanczos)
case FitOutside:
// Resize so smallest dimension fits, may exceed target on other dimension
bounds := img.Bounds()
origW := bounds.Dx()
origH := bounds.Dy()
scaleW := float64(width) / float64(origW)
scaleH := float64(height) / float64(origH)
scale := scaleW
if scaleH > scaleW {
scale = scaleH
}
newW := int(float64(origW) * scale)
newH := int(float64(origH) * scale)
return imaging.Resize(img, newW, newH, imaging.Lanczos)
default:
// Default to cover
return imaging.Fill(img, width, height, imaging.Center, imaging.Lanczos)
}
}
const defaultQuality = 85
// encode encodes an image to the specified format.
func (p *ImageProcessor) encode(img image.Image, format ImageFormat, quality int) ([]byte, error) {
if quality <= 0 {
quality = defaultQuality
}
var buf bytes.Buffer
switch format {
case FormatJPEG:
err := jpeg.Encode(&buf, img, &jpeg.Options{Quality: quality})
if err != nil {
return nil, err
}
case FormatPNG:
err := png.Encode(&buf, img)
if err != nil {
return nil, err
}
case FormatGIF:
err := gif.Encode(&buf, img, nil)
if err != nil {
return nil, err
}
case FormatWebP:
// Pure Go doesn't have WebP encoder, fall back to PNG
// TODO: Add WebP encoding support via external library
err := png.Encode(&buf, img)
if err != nil {
return nil, err
}
case FormatAVIF:
// AVIF not supported in pure Go, fall back to JPEG
err := jpeg.Encode(&buf, img, &jpeg.Options{Quality: quality})
if err != nil {
return nil, err
}
default:
return nil, fmt.Errorf("unsupported output format: %s", format)
}
return buf.Bytes(), nil
}
// formatFromString converts a format string to ImageFormat.
func (p *ImageProcessor) formatFromString(format string) ImageFormat {
switch format {
case "jpeg":
return FormatJPEG
case "png":
return FormatPNG
case "gif":
return FormatGIF
case "webp":
return FormatWebP
default:
return FormatJPEG
}
}

242
internal/imgcache/processor_test.go Normal file
View File

@@ -0,0 +1,242 @@
package imgcache
import (
"bytes"
"context"
"image"
"image/color"
"image/jpeg"
"image/png"
"io"
"testing"
)
// createTestJPEG creates a simple test JPEG image.
func createTestJPEG(t *testing.T, width, height int) []byte {
t.Helper()
img := image.NewRGBA(image.Rect(0, 0, width, height))
// Fill with a gradient
for y := 0; y < height; y++ {
for x := 0; x < width; x++ {
img.Set(x, y, color.RGBA{
R: uint8(x * 255 / width),
G: uint8(y * 255 / height),
B: 128,
A: 255,
})
}
}
var buf bytes.Buffer
if err := jpeg.Encode(&buf, img, &jpeg.Options{Quality: 90}); err != nil {
t.Fatalf("failed to encode test JPEG: %v", err)
}
return buf.Bytes()
}
// createTestPNG creates a simple test PNG image.
func createTestPNG(t *testing.T, width, height int) []byte {
t.Helper()
img := image.NewRGBA(image.Rect(0, 0, width, height))
for y := 0; y < height; y++ {
for x := 0; x < width; x++ {
img.Set(x, y, color.RGBA{
R: uint8(x * 255 / width),
G: uint8(y * 255 / height),
B: 128,
A: 255,
})
}
}
var buf bytes.Buffer
if err := png.Encode(&buf, img); err != nil {
t.Fatalf("failed to encode test PNG: %v", err)
}
return buf.Bytes()
}
func TestImageProcessor_ResizeJPEG(t *testing.T) {
proc := NewImageProcessor()
ctx := context.Background()
input := createTestJPEG(t, 800, 600)
req := &ImageRequest{
Size: Size{Width: 400, Height: 300},
Format: FormatJPEG,
Quality: 85,
FitMode: FitCover,
}
result, err := proc.Process(ctx, bytes.NewReader(input), req)
if err != nil {
t.Fatalf("Process() error = %v", err)
}
defer result.Content.Close()
if result.Width != 400 {
t.Errorf("Process() width = %d, want 400", result.Width)
}
if result.Height != 300 {
t.Errorf("Process() height = %d, want 300", result.Height)
}
if result.ContentLength == 0 {
t.Error("Process() returned zero content length")
}
// Verify it's valid JPEG by reading the content
data, err := io.ReadAll(result.Content)
if err != nil {
t.Fatalf("failed to read result: %v", err)
}
mime, err := DetectFormat(data)
if err != nil {
t.Fatalf("DetectFormat() error = %v", err)
}
if mime != MIMETypeJPEG {
t.Errorf("Output format = %v, want %v", mime, MIMETypeJPEG)
}
}
func TestImageProcessor_ConvertToPNG(t *testing.T) {
proc := NewImageProcessor()
ctx := context.Background()
input := createTestJPEG(t, 200, 150)
req := &ImageRequest{
Size: Size{Width: 200, Height: 150},
Format: FormatPNG,
FitMode: FitCover,
}
result, err := proc.Process(ctx, bytes.NewReader(input), req)
if err != nil {
t.Fatalf("Process() error = %v", err)
}
defer result.Content.Close()
data, err := io.ReadAll(result.Content)
if err != nil {
t.Fatalf("failed to read result: %v", err)
}
mime, err := DetectFormat(data)
if err != nil {
t.Fatalf("DetectFormat() error = %v", err)
}
if mime != MIMETypePNG {
t.Errorf("Output format = %v, want %v", mime, MIMETypePNG)
}
}
func TestImageProcessor_OriginalSize(t *testing.T) {
proc := NewImageProcessor()
ctx := context.Background()
input := createTestJPEG(t, 640, 480)
req := &ImageRequest{
Size: Size{Width: 0, Height: 0}, // Original size
Format: FormatJPEG,
Quality: 85,
FitMode: FitCover,
}
result, err := proc.Process(ctx, bytes.NewReader(input), req)
if err != nil {
t.Fatalf("Process() error = %v", err)
}
defer result.Content.Close()
if result.Width != 640 {
t.Errorf("Process() width = %d, want 640", result.Width)
}
if result.Height != 480 {
t.Errorf("Process() height = %d, want 480", result.Height)
}
}
func TestImageProcessor_FitContain(t *testing.T) {
proc := NewImageProcessor()
ctx := context.Background()
// 800x400 image (2:1 aspect) into 400x400 box with contain
// Should result in 400x200 (maintaining aspect ratio)
input := createTestJPEG(t, 800, 400)
req := &ImageRequest{
Size: Size{Width: 400, Height: 400},
Format: FormatJPEG,
Quality: 85,
FitMode: FitContain,
}
result, err := proc.Process(ctx, bytes.NewReader(input), req)
if err != nil {
t.Fatalf("Process() error = %v", err)
}
defer result.Content.Close()
// With contain, the image should fit within the box
if result.Width > 400 || result.Height > 400 {
t.Errorf("Process() size %dx%d exceeds 400x400 box", result.Width, result.Height)
}
}
func TestImageProcessor_ProcessPNG(t *testing.T) {
proc := NewImageProcessor()
ctx := context.Background()
input := createTestPNG(t, 400, 300)
req := &ImageRequest{
Size: Size{Width: 200, Height: 150},
Format: FormatPNG,
FitMode: FitCover,
}
result, err := proc.Process(ctx, bytes.NewReader(input), req)
if err != nil {
t.Fatalf("Process() error = %v", err)
}
defer result.Content.Close()
if result.Width != 200 {
t.Errorf("Process() width = %d, want 200", result.Width)
}
if result.Height != 150 {
t.Errorf("Process() height = %d, want 150", result.Height)
}
}
func TestImageProcessor_ImplementsInterface(t *testing.T) {
// Verify ImageProcessor implements Processor interface
var _ Processor = (*ImageProcessor)(nil)
}
func TestImageProcessor_SupportedFormats(t *testing.T) {
proc := NewImageProcessor()
inputFormats := proc.SupportedInputFormats()
if len(inputFormats) == 0 {
t.Error("SupportedInputFormats() returned empty slice")
}
outputFormats := proc.SupportedOutputFormats()
if len(outputFormats) == 0 {
t.Error("SupportedOutputFormats() returned empty slice")
}
}