[C#]几种Bitmap比较方式_.NET_编程开发_程序员俱乐部

这里选取图片，规格如下：

大小：

关键代码：

class="csharpcode">using System;
using System.Diagnostics;
using System.Drawing;
using System.Drawing.Imaging;
using System.IO;
using System.Runtime.InteropServices;

namespace ConsoleApplication27
{
    class Program
    {
        static void Main(string[] args)
        {
            try
            {
                Stopwatch _watch = new Stopwatch();
                _watch.Start();
                bool _compareByMenCmpResult = Resource1.cat.CompareByMemCmp(Resource1.cat);
                _watch.Stop();
                Console.WriteLine(string.Format("CompareByMemCmp: {0} {1}", _compareByMenCmpResult, _watch.ElapsedMilliseconds));
                _watch.Reset();
                _watch.Start();
                bool _compareByPixel = Resource1.cat.CompareByPixel(Resource1.cat);
                _watch.Stop();
                Console.WriteLine(string.Format("CompareByPixel: {0} {1}", _compareByPixel, _watch.ElapsedMilliseconds));
                _watch.Reset();
                _watch.Start();
                bool _compareByBase64String = Resource1.cat.CompareByBase64String(Resource1.cat);
                _watch.Stop();
                Console.WriteLine(string.Format("CompareByBase64String: {0} {1}", _compareByBase64String, _watch.ElapsedMilliseconds));
                _watch.Reset();
                _watch.Start();
                bool _compareByArray = Resource1.cat.CompareByArray(Resource1.cat);
                _watch.Stop();
                Console.WriteLine(string.Format("CompareByArray: {0} {1}", _compareByArray, _watch.ElapsedMilliseconds));
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
            finally
            {
                Console.ReadLine();
            }
        }
    }
    public static class ImageTool
    {
        [DllImport("msvcrt.dll")]
        private static extern int memcmp(IntPtr b1, IntPtr b2, long count);
        /// <summary>
        /// Bitmap比较
        /// </summary>
        /// <param name="b1">Bitmap1</param>
        /// <param name="b2">Bitmap2</param>
        /// <returns>比较结果</returns>
        public static bool CompareByMemCmp(this Bitmap b1, Bitmap b2)
        {
            /*说明
             *参考链接：
             *http://stackoverflow.com/questions/2031217/what-is-the-fastest-way-i-can-compare-two-equal-size-bitmaps-to-determine-whethe
             */
            if ((b1 == null) != (b2 == null)) return false;
            if (b1.Size != b2.Size) return false;

            BitmapData _bdata1 = b1.LockBits(new Rectangle(new Point(0, 0), b1.Size), ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb);
            BitmapData _bdata2 = b2.LockBits(new Rectangle(new Point(0, 0), b2.Size), ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb);

            try
            {
                IntPtr _bd1scan0 = _bdata1.Scan0;
                IntPtr _bd2scan0 = _bdata2.Scan0;
                int _stride = _bdata1.Stride;
                int _len = _stride * b1.Height;
                return memcmp(_bd1scan0, _bd2scan0, _len) == 0;
            }
            finally
            {
                b1.UnlockBits(_bdata1);
                b2.UnlockBits(_bdata2);
            }
        }
        /// <summary>
        /// 通过比较bitmap两者ToBase64String来判断是否相等
        /// </summary>
        /// <param name="b1">Bitmap1</param>
        /// <param name="b2">Bitmap2</param>
        /// <returns>比较结果</returns>
        public static bool CompareByBase64String(this Bitmap b1, Bitmap b2)
        {
            /*说明
            *参考链接：
            *http://blogs.msdn.com/b/domgreen/archive/2009/09/06/comparing-two-images-in-c.aspx
            */
            string _b1Base64String, _b2Base64String;
            MemoryStream _ms = new MemoryStream();
            try
            {
                b1.Save(_ms, ImageFormat.Png);
                _b1Base64String = Convert.ToBase64String(_ms.ToArray());
                _ms.Position = 0;

                b2.Save(_ms, ImageFormat.Png);
                _b2Base64String = Convert.ToBase64String(_ms.ToArray());
            }
            finally
            {
                _ms.Close();
            }
            return _b1Base64String.Equals(_b2Base64String);
        }
        /// <summary>
        /// 通过比较bitmap两者像素颜色来判断两者是否相等
        /// </summary>
        /// <param name="b1">Bitmap1</param>
        /// <param name="b2">Bitmap2</param>
        /// <returns>比较结果</returns>
        public static bool CompareByPixel(this Bitmap b1, Bitmap b2)
        {
            /*说明
             *参考链接：
             *http://blogs.msdn.com/b/domgreen/archive/2009/09/06/comparing-two-images-in-c.aspx
             */
            bool _flag = false;
            if (b1.Width == b2.Width && b1.Height == b2.Height)
            {
                _flag = true;
                Color _pixel1;
                Color _pixel2;
                for (int i = 0; i < b1.Width; i++)
                {
                    for (int j = 0; j < b1.Height; j++)
                    {
                        _pixel1 = b1.GetPixel(i, j);
                        _pixel2 = b2.GetPixel(i, j);
                        if (_pixel1 != _pixel2)
                        {
                            _flag = false;
                            break;
                        }
                    }
                }
            }
            return _flag;
        }
        /// <summary>
        /// memcmp API
        /// </summary>
        /// <param name="b1">字节数组1</param>
        /// <param name="b2">字节数组2</param>
        /// <returns>如果两个数组相同，返回0；如果数组1小于数组2，返回小于0的值；如果数组1大于数组2，返回大于0的值。</returns>
        [DllImport("msvcrt.dll")]
        private static extern IntPtr memcmp(byte[] b1, byte[] b2, IntPtr count);
        /// <summary>
        /// 通过比较bitmap两者byte[]来判断是否相等
        /// </summary>
        /// <param name="b1">Bitmap1</param>
        /// <param name="b2">Bitmap2</param>
        /// <returns>比较结果</returns>
        public static bool CompareByArray(this Bitmap b1, Bitmap b2)
        {
            /*说明
            *参考链接：
            *http://www.cnblogs.com/zgqys1980/archive/2009/07/13/1522546.html
            */
            IntPtr _result = new IntPtr(-1);
            MemoryStream _ms = new MemoryStream();
            try
            {
                b1.Save(_ms, ImageFormat.Png);
                byte[] _b1Array = _ms.ToArray();
                _ms.Position = 0;

                b2.Save(_ms, ImageFormat.Png);
                byte[] _b2Array = _ms.ToArray();

                _result = memcmp(_b1Array, _b2Array, new IntPtr(_b1Array.Length));
            }
            finally
            {
                _ms.Close();
            }
            return _result.ToInt32() == 0;
        }
    }
}

希望有所帮助！