Added: resize functionality using github.com/disintegration/imaging, dependencies are now managed using Go Modules, initial testing script.

cmd/webimg/main.go

@@ -84,6 +84,13 @@ func main() {
 			} else {
 				fmt.Println("No image given to watermark!")
 			}
+		case "resize":
+			doResize := webimg.Resize("smplayer_preferences.jpg", "smplayer_preferences_resize.jpg", 200, 0)
+			if doResize != nil {
+				fmt.Println("There was an error watermarking image...")
+			} else {
+				fmt.Println("Image resized.")
+			}
 		default:
 			fmt.Println("Wrong subcommand provided!")
 		}

go.mod

@@ -0,0 +1,5 @@
+module code.gyt.is/webimg
+
+go 1.14
+
+require github.com/disintegration/imaging v1.6.2

go.sum

@@ -0,0 +1,5 @@
+github.com/disintegration/imaging v1.6.2 h1:w1LecBlG2Lnp8B3jk5zSuNqd7b4DXhcjwek1ei82L+c=
+github.com/disintegration/imaging v1.6.2/go.mod h1:44/5580QXChDfwIclfc/PCwrr44amcmDAg8hxG0Ewe4=
+golang.org/x/image v0.0.0-20191009234506-e7c1f5e7dbb8 h1:hVwzHzIUGRjiF7EcUjqNxk3NCfkPxbDKRdnNE1Rpg0U=
+golang.org/x/image v0.0.0-20191009234506-e7c1f5e7dbb8/go.mod h1:FeLwcggjj3mMvU+oOTbSwawSJRM1uh48EjtB4UJZlP0=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=

resize.go

@@ -0,0 +1,35 @@
+/*
+ * Copyright © 2020 Gytis Repečka (gytis@repecka.com)
+ *
+ * This file is part of webimg.
+ *
+ * webimg is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, included
+ * in the LICENSE file in this source code package.
+ */
+
+ package webimg
+
+ import (
+ 	"log"
+  "github.com/disintegration/imaging"
+ )
+
+ func Resize(imagePath, resultPath string, resultWidth, resultHeight int) (err error) {
+   // Open a test image.
+   src, err := imaging.Open(imagePath)
+   if err != nil {
+     log.Fatalf("failed to open image: %v", err)
+   }
+
+   // Resize the cropped image to width = 200px preserving the aspect ratio.
+   src = imaging.Resize(src, resultWidth, resultHeight, imaging.Lanczos)
+
+   // Save the resulting image as JPEG.
+   err = imaging.Save(src, resultPath)
+   if err != nil {
+     log.Fatalf("failed to save image: %v", err)
+   }
+
+   return err
+ }

webimg_test.go

@@ -0,0 +1,11 @@
+package webimg
+
+import "testing"
+
+func TestWatermark(t *testing.T) {
+    // want := nil
+    var want error = nil
+    if got := Watermark("cmd/webimg/smplayer_preferences.jpg", "cmd/webimg/watermark_inretio-logo.png", "cmd/webimg/test_result_img.jpg", 30, 30, 70); got != want {
+        t.Errorf("Watermark = %q, want %q", got, want)
+    }
+}