Image图片处理

public class Imager
    {
        #region 正方型裁剪并缩放

        /// <summary>
        /// 正方型裁剪
        /// 以图片中心为轴心，截取正方型，然后等比缩放
        /// 用于头像处理
        /// </summary>
        /// <param name="fromFile">原图Stream对象</param>
        /// <param name="fileSaveUrl">缩略图存放地址</param>
        /// <param name="side">指定的边长（正方型）</param>
        /// <param name="quality">质量（范围0-100）</param>
        public static void CutForSquare(System.IO.Stream fromFile, string fileSaveUrl, int side, int quality)
        {
            //创建目录
            string dir = Path.GetDirectoryName(fileSaveUrl);
            if (!Directory.Exists(dir))
                Directory.CreateDirectory(dir);

            //原始图片（获取原始图片创建对象，并使用流中嵌入的颜色管理信息）
            System.Drawing.Image initImage = System.Drawing.Image.FromStream(fromFile, true);

            //原图宽高均小于模版，不作处理，直接保存
            if (initImage.Width <= side && initImage.Height <= side) {
                initImage.Save(fileSaveUrl, System.Drawing.Imaging.ImageFormat.Jpeg);
            } else {
                //原始图片的宽、高
                int initWidth = initImage.Width;
                int initHeight = initImage.Height;

                //非正方型先裁剪为正方型
                if (initWidth != initHeight) {
                    //截图对象
                    System.Drawing.Image pickedImage = null;
                    System.Drawing.Graphics pickedG = null;

                    //宽大于高的横图
                    if (initWidth > initHeight) {
                        //对象实例化
                        pickedImage = new System.Drawing.Bitmap(initHeight, initHeight);
                        pickedG = System.Drawing.Graphics.FromImage(pickedImage);
                        //设置质量
                        pickedG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
                        pickedG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
                        //定位
                        Rectangle fromR = new Rectangle((initWidth - initHeight) / , , initHeight, initHeight);
                        Rectangle toR = new Rectangle(, , initHeight, initHeight);
                        //画图
                        pickedG.DrawImage(initImage, toR, fromR, System.Drawing.GraphicsUnit.Pixel);
                        //重置宽
                        initWidth = initHeight;
                    }
                        //高大于宽的竖图
                    else {
                        //对象实例化
                        pickedImage = new System.Drawing.Bitmap(initWidth, initWidth);
                        pickedG = System.Drawing.Graphics.FromImage(pickedImage);
                        //设置质量
                        pickedG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
                        pickedG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
                        //定位
                        Rectangle fromR = new Rectangle(, (initHeight - initWidth) / , initWidth, initWidth);
                        Rectangle toR = new Rectangle(, , initWidth, initWidth);
                        //画图
                        pickedG.DrawImage(initImage, toR, fromR, System.Drawing.GraphicsUnit.Pixel);
                        //重置高
                        initHeight = initWidth;
                    }

                    //将截图对象赋给原图
                    initImage = (System.Drawing.Image)pickedImage.Clone();
                    //释放截图资源
                    pickedG.Dispose();
                    pickedImage.Dispose();
                }

                //缩略图对象
                System.Drawing.Image resultImage = new System.Drawing.Bitmap(side, side);
                System.Drawing.Graphics resultG = System.Drawing.Graphics.FromImage(resultImage);
                //设置质量
                resultG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
                resultG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
                //用指定背景色清空画布
                resultG.Clear(Color.White);
                //绘制缩略图
                resultG.DrawImage(initImage, new System.Drawing.Rectangle(, , side, side), new System.Drawing.Rectangle(, , initWidth, initHeight), System.Drawing.GraphicsUnit.Pixel);

                //关键质量控制
                //获取系统编码类型数组,包含了jpeg,bmp,png,gif,tiff
                ImageCodecInfo[] icis = ImageCodecInfo.GetImageEncoders();
                ImageCodecInfo ici = null;
                foreach (ImageCodecInfo i in icis) {
                    if (i.MimeType == "image/jpeg" || i.MimeType == "image/bmp" || i.MimeType == "image/png" || i.MimeType == "image/gif") {
                        ici = i;
                    }
                }
                EncoderParameters ep = new EncoderParameters();
                ep.Param[] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, (long)quality);

                //保存缩略图
                resultImage.Save(fileSaveUrl, ici, ep);

                //释放关键质量控制所用资源
                ep.Dispose();

                //释放缩略图资源
                resultG.Dispose();
                resultImage.Dispose();

                //释放原始图片资源
                initImage.Dispose();
            }
        }

        #endregion

        #region 自定义裁剪并缩放

        /// <summary>
        /// 指定长宽裁剪
        /// 按模版比例最大范围的裁剪图片并缩放至模版尺寸
        /// </summary>
        /// <param name="fromFile">原图Stream对象</param>
        /// <param name="fileSaveUrl">保存路径</param>
        /// <param name="maxWidth">最大宽(单位:px)</param>
        /// <param name="maxHeight">最大高(单位:px)</param>
        /// <param name="quality">质量（范围0-100）</param>
        public static void CutForCustom(System.IO.Stream fromFile, string fileSaveUrl, int maxWidth, int maxHeight, int quality)
        {
            //从文件获取原始图片，并使用流中嵌入的颜色管理信息
            System.Drawing.Image initImage = System.Drawing.Image.FromStream(fromFile, true);

            //原图宽高均小于模版，不作处理，直接保存
            if (initImage.Width <= maxWidth && initImage.Height <= maxHeight) {
                initImage.Save(fileSaveUrl, System.Drawing.Imaging.ImageFormat.Jpeg);
            } else {
                if (maxWidth == ) maxWidth = initImage.Width;
                if (maxHeight == ) maxHeight = initImage.Height;

                //模版的宽高比例
                double templateRate = (double)maxWidth / maxHeight;
                //原图片的宽高比例
                double initRate = (double)initImage.Width / initImage.Height;

                //原图与模版比例相等，直接缩放
                if (templateRate == initRate) {
                    //按模版大小生成最终图片
                    System.Drawing.Image templateImage = new System.Drawing.Bitmap(maxWidth, maxHeight);
                    System.Drawing.Graphics templateG = System.Drawing.Graphics.FromImage(templateImage);
                    templateG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
                    templateG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
                    templateG.Clear(Color.White);
                    templateG.DrawImage(initImage, new System.Drawing.Rectangle(, , maxWidth, maxHeight), new System.Drawing.Rectangle(, , initImage.Width, initImage.Height), System.Drawing.GraphicsUnit.Pixel);
                    templateImage.Save(fileSaveUrl, System.Drawing.Imaging.ImageFormat.Jpeg);
                }
                    //原图与模版比例不等，裁剪后缩放
                else {
                    //裁剪对象
                    System.Drawing.Image pickedImage = null;
                    System.Drawing.Graphics pickedG = null;

                    //定位
                    Rectangle fromR = new Rectangle(, , , );//原图裁剪定位
                    Rectangle toR = new Rectangle(, , , );//目标定位

                    //宽为标准进行裁剪
                    if (templateRate > initRate) {
                        //裁剪对象实例化
                        pickedImage = new System.Drawing.Bitmap(initImage.Width, (int)System.Math.Floor(initImage.Width / templateRate));
                        pickedG = System.Drawing.Graphics.FromImage(pickedImage);

                        //裁剪源定位
                        fromR.X = ;
                        fromR.Y = (int)System.Math.Floor((initImage.Height - initImage.Width / templateRate) / );
                        fromR.Width = initImage.Width;
                        fromR.Height = (int)System.Math.Floor(initImage.Width / templateRate);

                        //裁剪目标定位
                        toR.X = ;
                        toR.Y = ;
                        toR.Width = initImage.Width;
                        toR.Height = (int)System.Math.Floor(initImage.Width / templateRate);
                    }
                        //高为标准进行裁剪
                    else {
                        pickedImage = new System.Drawing.Bitmap((int)System.Math.Floor(initImage.Height * templateRate), initImage.Height);
                        pickedG = System.Drawing.Graphics.FromImage(pickedImage);

                        fromR.X = (int)System.Math.Floor((initImage.Width - initImage.Height * templateRate) / );
                        fromR.Y = ;
                        fromR.Width = (int)System.Math.Floor(initImage.Height * templateRate);
                        fromR.Height = initImage.Height;

                        toR.X = ;
                        toR.Y = ;
                        toR.Width = (int)System.Math.Floor(initImage.Height * templateRate);
                        toR.Height = initImage.Height;
                    }

                    //设置质量
                    pickedG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
                    pickedG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

                    //裁剪
                    pickedG.DrawImage(initImage, toR, fromR, System.Drawing.GraphicsUnit.Pixel);

                    //按模版大小生成最终图片
                    System.Drawing.Image templateImage = new System.Drawing.Bitmap(maxWidth, maxHeight);
                    System.Drawing.Graphics templateG = System.Drawing.Graphics.FromImage(templateImage);
                    templateG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
                    templateG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
                    templateG.Clear(Color.White);
                    templateG.DrawImage(pickedImage, new System.Drawing.Rectangle(, , maxWidth, maxHeight), new System.Drawing.Rectangle(, , pickedImage.Width, pickedImage.Height), System.Drawing.GraphicsUnit.Pixel);

                    //关键质量控制
                    //获取系统编码类型数组,包含了jpeg,bmp,png,gif,tiff
                    ImageCodecInfo[] icis = ImageCodecInfo.GetImageEncoders();
                    ImageCodecInfo ici = null;
                    foreach (ImageCodecInfo i in icis) {
                        if (i.MimeType == "image/jpeg" || i.MimeType == "image/bmp" || i.MimeType == "image/png" || i.MimeType == "image/gif") {
                            ici = i;
                        }
                    }
                    EncoderParameters ep = new EncoderParameters();
                    ep.Param[] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, (long)quality);

                    //保存缩略图
                    templateImage.Save(fileSaveUrl, ici, ep);
                    //templateImage.Save(fileSaveUrl, System.Drawing.Imaging.ImageFormat.Jpeg);

                    //释放资源
                    templateG.Dispose();
                    templateImage.Dispose();

                    pickedG.Dispose();
                    pickedImage.Dispose();
                }
            }

            //释放资源
            initImage.Dispose();
        }
        #endregion

        /// <summary>
        /// 图片等比缩放
        /// </summary>
        /// <param name="filePath">原图Stream对象</param>
        /// <param name="targetPath">缩略图存放地址</param>
        /// <param name="targetWidth">指定的最大宽度</param>
        /// <param name="targetHeight">指定的最大高度</param>
        /// <param name="watermarkText">水印文字(为""表示不使用水印)</param>
        /// <param name="watermarkImage">水印图片路径(为""表示不使用水印)</param>
        public static void Resize(string filePath, string targetPath, double targetWidth, double targetHeight, string watermarkText = "", string watermarkImage = "")
        {
            //创建目录
            string dir = Path.GetDirectoryName(targetPath);
            if (Directory.Exists(dir) == false) Directory.CreateDirectory(dir);

            //原始图片（获取原始图片创建对象，并使用流中嵌入的颜色管理信息）
            Image initImage = Image.FromFile(filePath, true);

            //原图宽高均小于模版或目标宽度均为0，不作处理，直接保存
            if (initImage.Width <= targetWidth && initImage.Height <= targetHeight || (targetWidth ==  && targetHeight == )) {
                //文字水印
                if (watermarkText != "") {
                    setWatermarkText(initImage, watermarkText);
                }

                //透明图片水印
                if (watermarkImage != "") {
                    setWatermarkImage(initImage, watermarkImage);
                }

                //保存
                initImage.Save(targetPath, ImageFormat.Jpeg);

            } else {
                //缩略图宽、高计算
                double newWidth = ;
                double newHeight = ;
                if (targetWidth == ) {
                    newWidth = initImage.Width * targetHeight / initImage.Height;
                    newHeight = targetHeight;
                } else if(targetHeight == ) {
                    newWidth = targetWidth;
                    newHeight = initImage.Height * targetWidth / initImage.Width;
                } else {
                    double scaleWidth = targetWidth / initImage.Width;
                    double scaleHeight = targetHeight / initImage.Height;
                    if (scaleWidth > scaleHeight) {
                        newWidth = initImage.Width * scaleHeight;
                        newHeight = initImage.Height * scaleHeight;
                    } else {
                        newWidth = initImage.Width * scaleWidth;
                        newHeight = initImage.Height * scaleWidth;
                    }
                }

                //生成新图
                //新建一个bmp图片
                Image newImage = new Bitmap((int)newWidth, (int)newHeight);
                //新建一个画板
                Graphics newG = Graphics.FromImage(newImage);

                //设置质量
                newG.InterpolationMode = InterpolationMode.HighQualityBicubic;
                newG.SmoothingMode = SmoothingMode.HighQuality;

                //置背景色
                newG.Clear(Color.White);
                //画图
                newG.DrawImage(initImage, new Rectangle(, , newImage.Width, newImage.Height), new Rectangle(, , initImage.Width, initImage.Height), GraphicsUnit.Pixel);

                //文字水印
                if (watermarkText != "") {
                    setWatermarkText(newImage, watermarkText);
                }

                //透明图片水印
                if (watermarkImage != "") {
                    setWatermarkImage(newImage, watermarkImage);
                }

                //保存缩略图
                newImage.Save(targetPath, ImageFormat.Jpeg);

                //释放资源
                newG.Dispose();
                newImage.Dispose();
            }

            initImage.Dispose();
        }

        private static void setWatermarkText(Image initImage, string watermarkText)
        {
            using (System.Drawing.Graphics gWater = System.Drawing.Graphics.FromImage(initImage)) {
                System.Drawing.Font fontWater = new Font("黑体", );
                System.Drawing.Brush brushWater = new SolidBrush(Color.White);
                gWater.DrawString(watermarkText, fontWater, brushWater, , );
                gWater.Dispose();
            }
        }
        private static void setWatermarkImage(Image initImage, string watermarkImage)
        {
            if (File.Exists(watermarkImage)) {
                //获取水印图片
                using (System.Drawing.Image wrImage = System.Drawing.Image.FromFile(watermarkImage)) {
                    //水印绘制条件：原始图片宽高均大于或等于水印图片
                    if (initImage.Width >= wrImage.Width && initImage.Height >= wrImage.Height) {
                        Graphics gWater = Graphics.FromImage(initImage);

                        //透明属性
                        ImageAttributes imgAttributes = new ImageAttributes();
                        ColorMap colorMap = new ColorMap();
                        colorMap.OldColor = Color.FromArgb(, , , );
                        colorMap.NewColor = Color.FromArgb(, , , );
                        ColorMap[] remapTable = { colorMap };
                        imgAttributes.SetRemapTable(remapTable, ColorAdjustType.Bitmap);

                        float[][] colorMatrixElements = {
                                   new float[] {1.0f,  0.0f,  0.0f,  0.0f, 0.0f},
                                   new float[] {0.0f,  1.0f,  0.0f,  0.0f, 0.0f},
                                   new float[] {0.0f,  0.0f,  1.0f,  0.0f, 0.0f},
                                   new float[] {0.0f,  0.0f,  0.0f,  0.5f, 0.0f},//透明度:0.5
                                   new float[] {0.0f,  0.0f,  0.0f,  0.0f, 1.0f}
                                };

                        ColorMatrix wmColorMatrix = new ColorMatrix(colorMatrixElements);
                        imgAttributes.SetColorMatrix(wmColorMatrix, ColorMatrixFlag.Default, ColorAdjustType.Bitmap);
                        gWater.DrawImage(wrImage, new Rectangle(initImage.Width - wrImage.Width, initImage.Height - wrImage.Height, wrImage.Width, wrImage.Height), , , wrImage.Width, wrImage.Height, GraphicsUnit.Pixel, imgAttributes);

                        gWater.Dispose();
                    }
                    wrImage.Dispose();
                }
            }
        }                

    }