C# ImageHelper 图片帮助类-开发框架文库

C# ImageHelper 图片帮助类
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    /// <summary>
    /// 图片帮助类
    /// </summary>
    public class ImageHelper
    {
        public const string IMAGE_FORMATS = ".jpg;.jpeg;.png;.bmp;.gif;";

        /// <summary>
        /// 判断是否图片类型
        /// </summary>
        /// <param name="fileExtension">文件扩展名</param>
        /// <returns></returns>
        public static bool IsImageType(string fileExtension)
        {
            return IMAGE_FORMATS.ToLower().Contains(fileExtension.ToLower());
        }

        /// <summary>
        /// byte数组转图片
        /// </summary>
        /// <param name="bs"></param>
        /// <returns></returns>
        public static Image FromBytes(byte[] bs)
        {
            if (bs == null)
            {
                return null;
            }

            using (MemoryStream stream = new MemoryStream(bs))
            {
                return Image.FromStream(stream);
            }
        }

        /// <summary>
        /// 指定颜色替换成另一种颜色
        /// </summary>
        /// <param name="img">原图</param>
        /// <param name="w">图宽</param>
        /// <param name="h">图高</param>
        /// <param name="R">要被替换颜色的RGB的R</param>
        /// <param name="G">要被替换颜色的RGB的G</param>
        /// <param name="B">要被替换颜色的RGB的B</param>
        /// <param name="r">替换色的RGB的R</param>
        /// <param name="g">替换色的RGB的G</param>
        /// <param name="b">替换色的RGB的B</param>
        /// <returns>处理后的结果图像</returns>
        public static Bitmap ReplaceColor(Bitmap img, int w, int h, int R, int G, int B, int r, int g, int b, int tolerance = 0)
        {
            //Bitmap bt = new Bitmap(ConvertTo32Bitmap(img)); //转换32位位图，注意：如果原图是32位，不需要转换！
            Bitmap bt = new Bitmap(img);
            Rectangle rect = new Rectangle(0, 0, w, h);
            BitmapData bmpdata = bt.LockBits(rect, ImageLockMode.ReadWrite, bt.PixelFormat);
            IntPtr ptr = bmpdata.Scan0;
            int bytes = Math.Abs(bmpdata.Stride) * bt.Height;
            byte[] rgbValues = new byte[bytes];
            System.Runtime.InteropServices.Marshal.Copy(ptr, rgbValues, 0, bytes);
            int len = rgbValues.Length;
            byte a = (byte)tolerance;
            byte R1 = (byte)R;
            byte G1 = (byte)G;
            byte B1 = (byte)B;
            byte r1 = (byte)r;
            byte g1 = (byte)g;
            byte b1 = (byte)b;
            for (int i = 0; i < len; i += 4)
            {
                //Format32bppRgb是用4个字节表示一个像素,第一个字节表示RGB的B值,第一个表示为G值,第三个表示为R值,第四个表示为Alpha值
                if (Math.Abs(rgbValues[i] - B1) < a && Math.Abs(rgbValues[i + 1] - G1) < a && Math.Abs(rgbValues[i + 2] - R1) < a)
                {
                    rgbValues[i] = b1;
                    rgbValues[i + 1] = g1;
                    rgbValues[i + 2] = r1;
                }
            }
            System.Runtime.InteropServices.Marshal.Copy(rgbValues, 0, ptr, bytes);
            bt.UnlockBits(bmpdata);
            return bt;
        }

        /// <summary>
        /// Image图像转化为32位位图
        /// </summary>
        /// <param name="img"></param>
        /// <returns></returns>
        public static Bitmap ConvertTo32Bitmap(Image img)
        {
            var bmp = new Bitmap(img.Width, img.Height, System.Drawing.Imaging.PixelFormat.Format32bppRgb);
            using (var gr = Graphics.FromImage(bmp))
                gr.DrawImage(img, new Rectangle(0, 0, img.Width, img.Height));
            return bmp;
        }

        /// <summary>
        /// 生成缩略图
        /// </summary>
        /// <param name="originalImage">源图</param>
        /// <param name="thumbnailPath">缩略图路径（物理路径）</param>
        /// <param name="width">缩略图宽度</param>
        /// <param name="height">缩略图高度</param>
        /// <param name="mode">生成缩略图的方式</param>    
        public static void MakeThumbnail(Image image, string thumbnailPath, int width, int height, string mode)
        {
            Image originalImage = image;
            int towidth = width;
            int toheight = height;

            int x = 0;
            int y = 0;
            int ow = originalImage.Width;
            int oh = originalImage.Height;

            switch (mode)
            {
                case "HW"://指定高宽缩放（可能变形）                
                    break;
                case "W"://指定宽，高按比例                    
                    toheight = originalImage.Height * width / originalImage.Width;
                    break;
                case "H"://指定高，宽按比例
                    towidth = originalImage.Width * height / originalImage.Height;
                    break;
                case "Cut"://指定高宽裁减（不变形）                
                    if ((double)originalImage.Width / (double)originalImage.Height > (double)towidth / (double)toheight)
                    {
                        oh = originalImage.Height;
                        ow = originalImage.Height * towidth / toheight;
                        y = 0;
                        x = (originalImage.Width - ow) / 2;
                    }
                    else
                    {
                        ow = originalImage.Width;
                        oh = originalImage.Width * height / towidth;
                        x = 0;
                        y = (originalImage.Height - oh) / 2;
                    }
                    break;
                default:
                    break;
            }

            //新建一个bmp图片
            Image bitmap = new System.Drawing.Bitmap(towidth, toheight);

            //新建一个画板
            Graphics g = System.Drawing.Graphics.FromImage(bitmap);

            //设置高质量插值法
            g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;

            //设置高质量,低速度呈现平滑程度
            g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

            //清空画布并以透明背景色填充
            g.Clear(Color.Transparent);

            //在指定位置并且按指定大小绘制原图片的指定部分
            g.DrawImage(originalImage, new Rectangle(0, 0, towidth, toheight),
                new Rectangle(x, y, ow, oh),
                GraphicsUnit.Pixel);

            try
            {
                //以jpg格式保存缩略图
                bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg);
            }
            catch (System.Exception e)
            {
                throw e;
            }
            finally
            {
                //originalImage.Dispose();
                bitmap.Dispose();
                g.Dispose();
            }
        }

        /// <summary>
        /// 生成缩略图
        /// </summary>
        /// <param name="originalImage">源图</param>
        /// <param name="width">缩略图宽度</param>
        /// <param name="height">缩略图高度</param>
        /// <param name="mode">生成缩略图的方式</param>    
        public static Image MakeThumbnail(Image image, int width, int height, string mode)
        {
            Image originalImage = image;
            int towidth = width;
            int toheight = height;

            int x = 0;
            int y = 0;
            int ow = originalImage.Width;
            int oh = originalImage.Height;

            switch (mode)
            {
                case "HW"://指定高宽缩放（可能变形）                
                    break;
                case "W"://指定宽，高按比例                    
                    toheight = originalImage.Height * width / originalImage.Width;
                    break;
                case "H"://指定高，宽按比例
                    towidth = originalImage.Width * height / originalImage.Height;
                    break;
                case "Cut"://指定高宽裁减（不变形）                
                    if ((double)originalImage.Width / (double)originalImage.Height > (double)towidth / (double)toheight)
                    {
                        oh = originalImage.Height;
                        ow = originalImage.Height * towidth / toheight;
                        y = 0;
                        x = (originalImage.Width - ow) / 2;
                    }
                    else
                    {
                        ow = originalImage.Width;
                        oh = originalImage.Width * height / towidth;
                        x = 0;
                        y = (originalImage.Height - oh) / 2;
                    }
                    break;
                default:
                    break;
            }

            //新建一个bmp图片
            Image bitmap = new System.Drawing.Bitmap(towidth, toheight);

            //新建一个画板
            Graphics g = System.Drawing.Graphics.FromImage(bitmap);

            //设置高质量插值法
            g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;

            //设置高质量,低速度呈现平滑程度
            g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

            //清空画布并以透明背景色填充
            g.Clear(Color.Transparent);

            //在指定位置并且按指定大小绘制原图片的指定部分
            g.DrawImage(originalImage, new Rectangle(0, 0, towidth, toheight),
                new Rectangle(x, y, ow, oh),
                GraphicsUnit.Pixel);

            try
            {
                //以jpg格式保存缩略图
                return bitmap;
            }
            catch (System.Exception e)
            {
                throw e;
            }
            finally
            {
                g.Dispose();
            }
        }

    }
原文链接：https://www.cscode.net/archive/newdoc/489508611391493.html
NewDoc C/S框架网 2023-12-04 15:15 2023-12-04 15:15