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using System.Drawing;
using System.Drawing.Imaging;

/* Dithering an image using the Floyd–Steinberg algorithm in C#
 * http://www.cyotek.com/blog/dithering-an-image-using-the-floyd-steinberg-algorithm-in-csharp
 *
 * Copyright © 2015 Cyotek Ltd.
 *
 * Licensed under the MIT License. See LICENSE.txt for the full text.
 */

namespace Cyotek.DitheringTest.Helpers
{
  internal static class ImageUtilities
  {
    #region Static Methods

    public static Bitmap Copy(this Image image)
    {
      Bitmap copy;

      copy = new Bitmap(image.Size.Width, image.Size.Height, PixelFormat.Format32bppArgb);

      using (Graphics g = Graphics.FromImage(copy))
      {
        g.Clear(Color.Transparent);
        g.PageUnit = GraphicsUnit.Pixel;
        g.DrawImage(image, new Rectangle(Point.Empty, image.Size));
      }

      return copy;
    }

    public static Bitmap ToBitmap(this ArgbColor[] data, Size size)
    {
      int height;
      int width;
      BitmapData bitmapData;
      Bitmap result;

      // Based on code from http://blog.biophysengr.net/2011/11/rapid-bitmap-access-using-unsafe-code.html

      result = new Bitmap(size.Width, size.Height, PixelFormat.Format32bppArgb);
      width = result.Width;
      height = result.Height;

      // Lock the entire bitmap
      bitmapData = result.LockBits(new Rectangle(0, 0, width, height), ImageLockMode.ReadWrite, PixelFormat.Format32bppArgb);

      //Enter unsafe mode so that we can use pointers
      unsafe
      {
        ArgbColor* pixelPtr;

        // Get a pointer to the beginning of the pixel data region
        // The upper-left corner
        pixelPtr = (ArgbColor*)bitmapData.Scan0;

        // Iterate through rows and columns
        for (int row = 0; row < size.Height; row++)
        {
          for (int col = 0; col < size.Width; col++)
          {
            int index;
            ArgbColor color;

            index = row * size.Width + col;
            color = data[index];

            // Set the pixel (fast!)
            *pixelPtr = color;

            // Update the pointer
            pixelPtr++;
          }
        }
      }

      // Unlock the bitmap
      result.UnlockBits(bitmapData);

      return result;
    }

    internal static ArgbColor[] GetPixelsFrom32BitArgbImage(this Bitmap bitmap)
    {
      int width;
      int height;
      BitmapData bitmapData;
      ArgbColor[] results;

      // NOTE: As the name should give a hint, it only supports 32bit ARGB images.
      // Don't rely on this for production, it needs expanding to support multiple other types

      width = bitmap.Width;
      height = bitmap.Height;
      results = new ArgbColor[width * height];
      bitmapData = bitmap.LockBits(new Rectangle(0, 0, width, height), ImageLockMode.WriteOnly, PixelFormat.Format32bppArgb);

      unsafe
      {
        ArgbColor* pixel;

        pixel = (ArgbColor*)bitmapData.Scan0;

        for (int row = 0; row < height; row++)
        {
          for (int col = 0; col < width; col++)
          {
            results[row * width + col] = *pixel;

            pixel++;
          }
        }
      }

      bitmap.UnlockBits(bitmapData);

      return results;
    }

    #endregion
  }
}