snapshot of https://github.com/mattermost/mattermost.git (master, 2026-09-16; blobs > 131072B omitted)

server/channels/app/imaging/encode.go

@@ -0,0 +1,88 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package imaging
+
+import (
+	"errors"
+	"fmt"
+	"image"
+	"io"
+
+	"image/jpeg"
+	"image/png"
+)
+
+// EncoderOptions holds configuration options for an image encoder.
+type EncoderOptions struct {
+	// The level of concurrency for the encoder. This defines a limit on the
+	// number of concurrently running encoding goroutines.
+	ConcurrencyLevel int
+}
+
+func (o *EncoderOptions) validate() error {
+	if o.ConcurrencyLevel < 0 {
+		return errors.New("ConcurrencyLevel must be non-negative")
+	}
+	return nil
+}
+
+// Decoder holds the necessary state to encode images.
+// This is safe to be used from multiple goroutines.
+type Encoder struct {
+	sem        chan struct{}
+	opts       EncoderOptions
+	pngEncoder *png.Encoder
+}
+
+// NewEncoder creates and returns a new image encoder with the given options.
+func NewEncoder(opts EncoderOptions) (*Encoder, error) {
+	var e Encoder
+	if err := opts.validate(); err != nil {
+		return nil, fmt.Errorf("imaging: error validating encoder options: %w", err)
+	}
+	if opts.ConcurrencyLevel > 0 {
+		e.sem = make(chan struct{}, opts.ConcurrencyLevel)
+	}
+	e.opts = opts
+	e.pngEncoder = &png.Encoder{
+		CompressionLevel: png.BestCompression,
+	}
+	return &e, nil
+}
+
+// EncodeJPEG encodes the given image in JPEG format and writes the data to
+// the passed writer.
+func (e *Encoder) EncodeJPEG(wr io.Writer, img image.Image, quality int) error {
+	if e.opts.ConcurrencyLevel > 0 {
+		e.sem <- struct{}{}
+		defer func() {
+			<-e.sem
+		}()
+	}
+
+	var encOpts jpeg.Options
+	encOpts.Quality = quality
+	if err := jpeg.Encode(wr, img, &encOpts); err != nil {
+		return fmt.Errorf("imaging: failed to encode jpeg: %w", err)
+	}
+
+	return nil
+}
+
+// EncodePNG encodes the given image in PNG format and writes the data to
+// the passed writer.
+func (e *Encoder) EncodePNG(wr io.Writer, img image.Image) error {
+	if e.opts.ConcurrencyLevel > 0 {
+		e.sem <- struct{}{}
+		defer func() {
+			<-e.sem
+		}()
+	}
+
+	if err := e.pngEncoder.Encode(wr, img); err != nil {
+		return fmt.Errorf("imaging: failed to encode png: %w", err)
+	}
+
+	return nil
+}