From 69f5d1ccb3dd7d905cea437bd1861bbe70da77dd Mon Sep 17 00:00:00 2001
From: David Vogel <Dadido3@aol.com>
Date: Mon, 15 Jan 2024 20:06:49 +0100
Subject: [PATCH] Add WebP encoder

---
 .vscode/settings.json     |  1 +
 bin/stitch/export-webp.go | 40 +++++++++++++++++++++++++++++++++++++++
 bin/stitch/main.go        |  8 ++++++--
 go.mod                    |  1 +
 go.sum                    |  2 ++
 5 files changed, 50 insertions(+), 2 deletions(-)
 create mode 100644 bin/stitch/export-webp.go

diff --git a/.vscode/settings.json b/.vscode/settings.json
index 9e5718a..456ba78 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -54,6 +54,7 @@
         "upscaled",
         "Vogel",
         "Voronoi",
+        "webp",
         "xmax",
         "xmin",
         "ymax",
diff --git a/bin/stitch/export-webp.go b/bin/stitch/export-webp.go
new file mode 100644
index 0000000..2fa3b46
--- /dev/null
+++ b/bin/stitch/export-webp.go
@@ -0,0 +1,40 @@
+// Copyright (c) 2024 David Vogel
+//
+// This software is released under the MIT License.
+// https://opensource.org/licenses/MIT
+
+package main
+
+import (
+	"fmt"
+	"image"
+	"log"
+	"os"
+
+	"github.com/chai2010/webp"
+)
+
+func exportWebP(stitchedImage image.Image, outputPath string) error {
+	log.Printf("Creating output file %q.", outputPath)
+
+	return exportWebPSilent(stitchedImage, outputPath)
+}
+
+func exportWebPSilent(stitchedImage image.Image, outputPath string) error {
+	bounds := stitchedImage.Bounds()
+	if bounds.Dx() > 16383 || bounds.Dy() > 16383 {
+		return fmt.Errorf("image size exceeds the maximum allowed size (16383) of a WebP image: %d x %d", bounds.Dx(), bounds.Dy())
+	}
+
+	f, err := os.Create(outputPath)
+	if err != nil {
+		return fmt.Errorf("failed to create file: %w", err)
+	}
+	defer f.Close()
+
+	if err = webp.Encode(f, stitchedImage, &webp.Options{Lossless: true}); err != nil {
+		return fmt.Errorf("failed to encode image %q: %w", outputPath, err)
+	}
+
+	return nil
+}
diff --git a/bin/stitch/main.go b/bin/stitch/main.go
index 6f9e3fd..ddee631 100644
--- a/bin/stitch/main.go
+++ b/bin/stitch/main.go
@@ -1,4 +1,4 @@
-// Copyright (c) 2019-2023 David Vogel
+// Copyright (c) 2019-2024 David Vogel
 //
 // This software is released under the MIT License.
 // https://opensource.org/licenses/MIT
@@ -22,7 +22,7 @@ import (
 var flagInputPath = flag.String("input", filepath.Join(".", "..", "..", "output"), "The source path of the image tiles to be stitched.")
 var flagEntitiesInputPath = flag.String("entities", filepath.Join(".", "..", "..", "output", "entities.json"), "The path to the entities.json file.")
 var flagPlayerPathInputPath = flag.String("player-path", filepath.Join(".", "..", "..", "output", "player-path.json"), "The path to the player-path.json file.")
-var flagOutputPath = flag.String("output", filepath.Join(".", "output.png"), "The path and filename of the resulting stitched image. Supported formats/file extensions: `.png`, `.jpg`, `.dzi`.")
+var flagOutputPath = flag.String("output", filepath.Join(".", "output.png"), "The path and filename of the resulting stitched image. Supported formats/file extensions: `.png`, `.webp`, `.jpg`, `.dzi`.")
 var flagScaleDivider = flag.Int("divide", 1, "A downscaling factor. 2 will produce an image with half the side lengths.")
 var flagBlendTileLimit = flag.Int("blend-tile-limit", 9, "Limits median blending to the n newest tiles by file modification time. If set to 0, all available tiles will be median blended.")
 var flagDZITileSize = flag.Int("dzi-tile-size", 512, "The size of the resulting deep zoom image (DZI) tiles in pixels.")
@@ -333,6 +333,10 @@ func main() {
 		if err := exportJPEG(stitchedImage, *flagOutputPath); err != nil {
 			log.Panicf("Export of JPEG file failed: %v", err)
 		}
+	case ".webp":
+		if err := exportWebP(stitchedImage, *flagOutputPath); err != nil {
+			log.Panicf("Export of WebP file failed: %v", err)
+		}
 	case ".dzi":
 		if err := exportDZI(stitchedImage, *flagOutputPath, *flagDZITileSize, *flagDZIOverlap); err != nil {
 			log.Panicf("Export of DZI file failed: %v", err)
diff --git a/go.mod b/go.mod
index bbda108..d8c9e9f 100644
--- a/go.mod
+++ b/go.mod
@@ -4,6 +4,7 @@ go 1.21
 
 require (
 	github.com/1lann/promptui v0.8.1-0.20220708222609-81fad96dd5e1
+	github.com/chai2010/webp v1.1.1
 	github.com/cheggaaa/pb/v3 v3.1.4
 	github.com/coreos/go-semver v0.3.1
 	github.com/kbinani/screenshot v0.0.0-20230812210009-b87d31814237
diff --git a/go.sum b/go.sum
index 3f0f526..f92e117 100644
--- a/go.sum
+++ b/go.sum
@@ -16,6 +16,8 @@ github.com/benoitkugler/textprocessing v0.0.3 h1:Q2X+Z6vxuW5Bxn1R9RaNt0qcprBfpc2
 github.com/benoitkugler/textprocessing v0.0.3/go.mod h1:/4bLyCf1QYywunMK3Gf89Nhb50YI/9POewqrLxWhxd4=
 github.com/campoy/embedmd v1.0.0 h1:V4kI2qTJJLf4J29RzI/MAt2c3Bl4dQSYPuflzwFH2hY=
 github.com/campoy/embedmd v1.0.0/go.mod h1:oxyr9RCiSXg0M3VJ3ks0UGfp98BpSSGr0kpiX3MzVl8=
+github.com/chai2010/webp v1.1.1 h1:jTRmEccAJ4MGrhFOrPMpNGIJ/eybIgwKpcACsrTEapk=
+github.com/chai2010/webp v1.1.1/go.mod h1:0XVwvZWdjjdxpUEIf7b9g9VkHFnInUSYujwqTLEuldU=
 github.com/cheggaaa/pb/v3 v3.1.4 h1:DN8j4TVVdKu3WxVwcRKu0sG00IIU6FewoABZzXbRQeo=
 github.com/cheggaaa/pb/v3 v3.1.4/go.mod h1:6wVjILNBaXMs8c21qRiaUM8BR82erfgau1DQ4iUXmSA=
 github.com/chzyer/logex v1.1.10/go.mod h1:+Ywpsq7O8HXn0nuIou7OrIPyXbp3wmkHB+jjWRnGsAI=