QrCodeBitmapExtensions.cs

//
// QR code generator library (.NET)
// https://github.com/manuelbl/QrCodeGenerator
//
// Copyright (c) 2021 Manuel Bleichenbacher
// Licensed under MIT License
// https://opensource.org/licenses/MIT
//

using SkiaSharp;
using System;
using System.IO;

namespace Net.Codecrete.QrCodeGenerator
{
  public static class QrCodeBitmapExtensions
  {
    /// <inheritdoc cref="ToBitmap(QrCode, int, int)"/>
    /// <param name="background">The background color.</param>
    /// <param name="foreground">The foreground color.</param>
    public static SKBitmap ToBitmap(this QrCode qrCode, int scale, int border, SKColor foreground, SKColor background)
    {
      // check arguments
      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 size = qrCode.Size;
      int dim = (size + border * 2) * scale;

      if (dim > short.MaxValue)
      {
        throw new ArgumentOutOfRangeException(nameof(scale), "Scale or border too large");
      }

      // create bitmap
      SKBitmap bitmap = new SKBitmap(dim, dim, SKColorType.Rgb888x, SKAlphaType.Opaque);

      using (SKCanvas canvas = new SKCanvas(bitmap))
      {
        // draw background
        using (SKPaint paint = new SKPaint { Color = background })
        {
          canvas.DrawRect(0, 0, dim, dim, paint);
        }

        // draw modules
        using (SKPaint paint = new SKPaint { Color = foreground })
        {
          for (int y = 0; y < size; y++)
          {
            for (int x = 0; x < size; x++)
            {
              if (qrCode.GetModule(x, y))
              {
                canvas.DrawRect((x + border) * scale, (y + border) * scale, scale, scale, paint);
              }
            }
          }
        }
      }

      return bitmap;
    }

    /// <summary>
    /// Creates a bitmap (raster image) of this QR code.
    /// <para>
    /// The <paramref name="scale"/> parameter specifies the scale of the image, which is
    /// equivalent to the width and height of each QR code module. Additionally, the number
    /// of modules to add as a border to all four sides can be specified.
    /// </para>
    /// <para>
    /// For example, <c>ToBitmap(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.
    /// </para>
    /// <para>
    /// The resulting bitmap uses the pixel format <see cref="PixelFormat.Format24bppRgb"/>.
    /// If not specified, the foreground color is black (0x000000) und the background color always white (0xFFFFFF).
    /// </para>
    /// </summary>
    /// <param name="scale">The width and height, in pixels, of each module.</param>
    /// <param name="border">The number of border modules to add to each of the four sides.</param>
    /// <returns>The created bitmap representing this QR code.</returns>
    /// <exception cref="ArgumentOutOfRangeException"><paramref name="scale"/> is 0 or negative, <paramref name="border"/> is negative
    /// or the resulting image is wider than 32,768 pixels.</exception>
    public static SKBitmap ToBitmap(this QrCode qrCode, int scale, int border)
    {
      return qrCode.ToBitmap(scale, border, SKColors.Black, SKColors.White);
    }

    /// <inheritdoc cref="ToPng(QrCode, int, int)"/>
    /// <param name="background">The background color.</param>
    /// <param name="foreground">The foreground color.</param>
    public static byte[] ToPng(this QrCode qrCode, int scale, int border, SKColor foreground, SKColor background)
    {
      using SKBitmap bitmap = qrCode.ToBitmap(scale, border, foreground, background);
      using SKData data = bitmap.Encode(SKEncodedImageFormat.Png, 90);
      return data.ToArray();
    }

    /// <summary>
    /// Creates a PNG image of this QR code and returns it as a byte array.
    /// <para>
    /// The <paramref name="scale"/> parameter specifies the scale of the image, which is
    /// equivalent to the width and height of each QR code module. Additionally, the number
    /// of modules to add as a border to all four sides can be specified.
    /// </para>
    /// <para>
    /// For example, <c>ToPng(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.
    /// </para>
    /// <para>
    /// If not specified, the foreground color is black (0x000000) und the background color always white (0xFFFFFF).
    /// </para>
    /// </summary>
    /// <param name="scale">The width and height, in pixels, of each module.</param>
    /// <param name="border">The number of border modules to add to each of the four sides.</param>
    /// <returns>The created bitmap representing this QR code.</returns>
    /// <exception cref="ArgumentOutOfRangeException"><paramref name="scale"/> is 0 or negative, <paramref name="border"/> is negative
    /// or the resulting image is wider than 32,768 pixels.</exception>
    public static byte[] ToPng(this QrCode qrCode, int scale, int border)
    {
      return qrCode.ToPng(scale, border, SKColors.Black, SKColors.White);
    }

    /// <inheritdoc cref="SaveAsPng(QrCode, string, int, int)"/>
    /// <param name="background">The background color.</param>
    /// <param name="foreground">The foreground color.</param>
    public static void SaveAsPng(this QrCode qrCode, string filename, int scale, int border, SKColor foreground, SKColor background)
    {
      using SKBitmap bitmap = qrCode.ToBitmap(scale, border, foreground, background);
      using SKData data = bitmap.Encode(SKEncodedImageFormat.Png, 90);
      using FileStream stream = File.OpenWrite(filename);
      data.SaveTo(stream);
    }

    /// <summary>
    /// Saves this QR code as a PNG file.
    /// <para>
    /// The <paramref name="scale"/> parameter specifies the scale of the image, which is
    /// equivalent to the width and height of each QR code module. Additionally, the number
    /// of modules to add as a border to all four sides can be specified.
    /// </para>
    /// <para>
    /// For example, <c>SaveAsPng("qrcode.png", 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.
    /// </para>
    /// <para>
    /// If not specified, the foreground color is black (0x000000) und the background color always white (0xFFFFFF).
    /// </para>
    /// </summary>
    /// <param name="scale">The width and height, in pixels, of each module.</param>
    /// <param name="border">The number of border modules to add to each of the four sides.</param>
    /// <exception cref="ArgumentOutOfRangeException"><paramref name="scale"/> is 0 or negative, <paramref name="border"/> is negative
    /// or the resulting image is wider than 32,768 pixels.</exception>
    public static void SaveAsPng(this QrCode qrCode, string filename, int scale, int border)
    {
      qrCode.SaveAsPng(filename, scale, border, SKColors.Black, SKColors.White);
    }
  }
}