Fork/Fork.Net/Y.Utils/ImageUtils/ImageHelper.cs

using System;
using System.Drawing;

namespace Y.Utils.ImageUtils
{
    public class ImageHelper
    {
        /// <summary> 
        /// 生成缩略图 
        /// </summary> 
        /// <param name="originalImagePath">源图路径（物理路径）</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 bool MakeThumbnail(string originalImagePath, string thumbnailPath, int width, int height, string mode)
        {
            Image originalImage = Image.FromFile(originalImagePath);
            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);
                return true;
            }
            catch (System.Exception e)
            {
                return false;
                //throw e;
            }
            finally
            {
                originalImage.Dispose();
                bitmap.Dispose();
                g.Dispose();
            }
        }
        /// <summary>
        /// 逆时针旋转图像
        /// </summary>
        /// <param name="originalImagePath">原始图像路径</param>
        /// <param name="saveImagePath">保存图像的路径</param>
        /// <param name = "angle" > 旋转角度[0, 360](前台给的) </ param >
        /// <returns></returns>
        public static bool RotateImg(string originalImagePath, string saveImagePath, int angle)
        {
            Image originalImage = Image.FromFile(originalImagePath);
            angle = angle % 360;
            //弧度转换  
            double radian = angle * Math.PI / 180.0;
            double cos = Math.Cos(radian);
            double sin = Math.Sin(radian);
            //原图的宽和高  
            int w = originalImage.Width;
            int h = originalImage.Height;
            int W = (int)(Math.Max(Math.Abs(w * cos - h * sin), Math.Abs(w * cos + h * sin)));
            int H = (int)(Math.Max(Math.Abs(w * sin - h * cos), Math.Abs(w * sin + h * cos)));
            //目标位图  
            Bitmap saveImage = new Bitmap(W, H);
            Graphics g = Graphics.FromImage(saveImage);
            g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.Bilinear;
            g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
            //计算偏移量  
            Point Offset = new Point((W - w) / 2, (H - h) / 2);
            //构造图像显示区域：让图像的中心与窗口的中心点一致  
            Rectangle rect = new Rectangle(Offset.X, Offset.Y, w, h);
            Point center = new Point(rect.X + rect.Width / 2, rect.Y + rect.Height / 2);
            g.TranslateTransform(center.X, center.Y);
            g.RotateTransform(360 - angle);
            //恢复图像在水平和垂直方向的平移  
            g.TranslateTransform(-center.X, -center.Y);
            g.DrawImage(originalImage, rect);
            //重至绘图的所有变换  
            g.ResetTransform();
            g.Save();
            //保存旋转后的图片  
            originalImage.Dispose();
            try
            {
                saveImage.Save(saveImagePath, System.Drawing.Imaging.ImageFormat.Jpeg);
                return true;
            }
            catch (Exception e) { return false; }
            finally
            {
                originalImage.Dispose();
                saveImage.Dispose();
                g.Dispose();
            }
        }
    }
}