Save QR code as image

dotnet/QrCodeGenerator/QrCode.cs

@@ -26,6 +26,8 @@ using System;
 using System.Collections;
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Drawing;
+using System.Drawing.Imaging;
 
 namespace Io.Nayuki.QrCodeGen
 {
@@ -356,6 +358,54 @@ namespace Io.Nayuki.QrCodeGen
             return 0 <= x && x < Size && 0 <= y && y < Size && _modules[y, x];
         }
 
+
+        /// <summary>
+        /// Returns a raster image depicting this QR Code, with the specified module scale and border modules.
+        /// </summary>
+        /// <remarks>
+        /// For example, <c>ToImage(scale: 10, border: 4)</c> means to pad the QR Code with 4 white
+        /// border modules on all four sides, and use 10&#xD7;10 pixels to represent each module.
+        /// The resulting image only contains the hex colors 000000 and FFFFFF.
+        /// </remarks>
+        /// <param name="scale">the side length (measured in pixels, must be positive) of each module</param>
+        /// <param name="border">the number of border modules to add, which must be non-negative</param>
+        /// <returns>a new image representing this QR Code, with padding and scaling</returns>
+        /// <exception cref="ArgumentOutOfRangeException">Thrown if the scale is 0 or negative, if the border is negative
+        /// or if the resulting image is wider than 32,768 pixels</exception>
+        public Bitmap ToImage(int scale, int border)
+        {
+            if (scale <= 0)
+            {
+                throw new ArgumentOutOfRangeException(nameof(scale), "Value out of range");
+            }
+            if (border < 0)
+            {
+                throw new ArgumentOutOfRangeException(nameof(border), "Value out of range");
+            }
+
+            int dim = (Size + border * 2) * scale;
+
+            if (dim > short.MaxValue)
+            {
+                throw new ArgumentOutOfRangeException(nameof(scale), "Scale or border too large");
+            }
+
+            Bitmap bitmap = new Bitmap(dim, dim, PixelFormat.Format24bppRgb);
+
+            // simple and inefficient
+            for (var y = 0; y < dim; y++)
+            {
+                for (var x = 0; x < dim; x++)
+                {
+                    bool color = GetModule(x / scale - border, y / scale - border);
+                    bitmap.SetPixel(x, y, color ? Color.Black : Color.White);
+                }
+            }
+
+            return bitmap;
+        }
+
+
         #endregion
 
 

dotnet/QrCodeGenerator/QrCodeGenerator.csproj

@@ -16,4 +16,8 @@
     <PackageReleaseNotes>Initial release for .NET</PackageReleaseNotes>
   </PropertyGroup>
 
+  <ItemGroup>
+    <PackageReference Include="System.Drawing.Common" Version="4.5.1" />
+  </ItemGroup>
+
 </Project>

dotnet/QrCodeGeneratorTest/PngTest.cs

@@ -0,0 +1,45 @@
+/* 
+ * QR Code generator library (.NET)
+ * 
+ * Copyright (c) Project Nayuki. (MIT License)
+ * https://www.nayuki.io/page/qr-code-generator-library
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to
+ * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+ * the Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ * - The above copyright notice and this permission notice shall be included in
+ *   all copies or substantial portions of the Software.
+ * - The Software is provided "as is", without warranty of any kind, express or
+ *   implied, including but not limited to the warranties of merchantability,
+ *   fitness for a particular purpose and noninfringement. In no event shall the
+ *   authors or copyright holders be liable for any claim, damages or other
+ *   liability, whether in an action of contract, tort or otherwise, arising from,
+ *   out of or in connection with the Software or the use or other dealings in the
+ *   Software.
+ */
+
+using System.Drawing.Imaging;
+using Xunit;
+using static Io.Nayuki.QrCodeGen.QrCode;
+
+namespace Io.Nayuki.QrCodeGen.Test
+{
+    public class PngTest
+    {
+        [Fact]
+        private void PngImage()
+        {
+            var qrCode = EncodeText("The quick brown fox jumps over the lazy dog", Ecc.High);
+            using (var bitmap = qrCode.ToImage(3, 4))
+            {
+                Assert.Equal(135, bitmap.Width);
+                Assert.Equal(135, bitmap.Height);
+
+                bitmap.Save("qrcode.png", ImageFormat.Png);
+            }
+        }
+    }
+}