add image api module

1 files changed, 44 insertions, 0 deletions

diff --git a/main.go b/main.go
index d8614ae..35ed343 100644
--- a/main.go
+++ b/main.go
@@ -8,6 +8,9 @@ import (
 	"errors"
 	"flag"
 	"fmt"
+	"image"
+	"image/jpeg"
+	"image/png"
 	"io"
 	"log"
 	"net/http"
@@ -21,6 +24,7 @@ import (
 	"time"
 
 	_ "github.com/mattn/go-sqlite3"
+	"github.com/nfnt/resize"
 )
 
 var debug bool
@@ -478,6 +482,45 @@ func main() {
 		return luaOk(l, res)
 	}
 
+	imageModule := make(map[string]any)
+	imageModule["create-thumbnail"] = func (l *Lua) int {
+		var in, out string
+		var width int
+		err := l.Scan(&in, &out, &width)
+		if err != nil {
+			return luaErr(l, err)
+		}
+		file, err := os.Open(in)
+		if err != nil {
+			return luaErr(l, err)
+		}
+		defer file.Close()
+		mimetype, err := mimetype(file)
+		if err != nil {
+			return luaErr(l, err)
+		}
+		var img image.Image
+		if mimetype == "image/jpeg" {
+			img, err = jpeg.Decode(file)
+		} else if mimetype == "image/png" {
+			img, err = png.Decode(file)
+		} else {
+			return luaErr(l, errors.New("unknown image type: only jpeg and png are supported"))
+		}
+		if err != nil {
+			return luaErr(l, err)
+		}
+		resizedImg := resize.Resize(uint(width), 0, img, resize.Lanczos3)
+		outFile, err := os.Create(out)
+		if err != nil {
+			return luaErr(l, err)
+		}
+		defer outFile.Close()
+		jpeg.Encode(outFile, resizedImg, nil)
+		return luaOk(l, nil)
+	}
+	imageModule["createThumbnail"] = imageModule["create-thumbnail"]
+
 	cryptoModule := make(map[string]any)
 	cryptoModule["sha1"] = func (l *Lua) int {
 		var str string
@@ -496,6 +539,7 @@ func main() {
 	module["db"] = dbModule
 	module["utf8"] = utf8Module
 	module["fs"] = fsModule
+	module["image"] = imageModule
 	module["crypto"] = cryptoModule
 	module["on-eval"] = func (l *Lua) int {
 		var evalFn LuaRef