using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.IO;
using System.Drawing;
using System.Windows.Forms;
using System.Windows.Forms.ComponentModel;

using System.Drawing.Imaging;
using System.Windows.Media.Imaging;
using System.Runtime.InteropServices;
using System.Windows.Media;
using System.Windows;

namespace WpfMosaic
{
    [StructLayout(LayoutKind.Sequential)]
    public struct PixelColor
    {
        public byte Blue;
        public byte Green;
        public byte Red;
        public byte Alpha;
    }

    public class Utils
    {
        public static PixelColor[,] GetPixels(BitmapSource source)
        {
            if (source.Format != PixelFormats.Bgra32)
                source = new FormatConvertedBitmap(source, PixelFormats.Bgra32, null, 0);
            PixelColor[,] pixels = new PixelColor[source.PixelWidth, source.PixelHeight];
            int stride = source.PixelWidth * ((source.Format.BitsPerPixel + 7) / 8);
            GCHandle pinnedPixels = GCHandle.Alloc(pixels, GCHandleType.Pinned);
            source.CopyPixels(
              new Int32Rect(0, 0, source.PixelWidth, source.PixelHeight),
              pinnedPixels.AddrOfPinnedObject(),
              pixels.GetLength(0) * pixels.GetLength(1) * 4,
                  stride);
            pinnedPixels.Free();
            return pixels;
        }
}
}

// 用法：
//var pixels = GetPixels(image);
//if(pixels[7, 3].Red > 4)