分为两部分，一个是操作类，另外一个是测试。直接上代码了
一、测试代码
private void button1_Click(object sender, EventArgs e) { string newSourcePath = ImgPath;//源图存放目录 string newNewDir = MakePath; //新图存放目录
string sourceFile = Path.Combine(ImgPath, "app1.jpg"); //获取原图路径 string newFile = string.Empty; //新图路径
ImgThumbnail iz = new ImgThumbnail(); Action<ImgThumbnail.ImgThumbnailType> Thumbnail = (type => { //生成质量 for (int i = 100; i >= 10; i -= 10) { //计算新图路径，测试命名：原图名_new_缩放类型_压缩质量.jpg newFile = Path.Combine(newNewDir, string.Format("app1_new_{1}_{0}.jpg", i, type.ToString())); //压缩图片 iz.Thumbnail(sourceFile, newFile, 100, 100, i, type); } }); Thumbnail(ImgThumbnail.ImgThumbnailType.Cut);//裁剪压缩（裁剪压缩还不好用，待调整！） Thumbnail(ImgThumbnail.ImgThumbnailType.H); //以高度为参照压缩，不变形 Thumbnail(ImgThumbnail.ImgThumbnailType.W); //以宽度为参照压缩，不变形 Thumbnail(ImgThumbnail.ImgThumbnailType.WH); //固定宽高压缩，变形 MessageBox.Show("完成"); }
二、操作类
using System.Drawing; using System.Drawing.Drawing2D; using System.Drawing.Imaging;
namespace MagickNet.App { /// <summary> /// 图片压缩 /// </summary> public class ImgThumbnail {
#region 枚举 /// <summary> /// 指定缩放类型 /// </summary> public enum ImgThumbnailType { /// <summary> /// 无 /// </summary> Nothing=0, /// <summary> /// 指定高宽缩放（可能变形） /// </summary> WH = 1, /// <summary> /// 指定宽，高按比例 /// </summary> W = 2, /// <summary> /// 指定高，宽按比例 /// </summary> H = 3, /// <summary> /// 指定高宽裁减（不变形） /// </summary> Cut = 4, /// <summary> /// 按照宽度成比例缩放后，按照指定的高度进行裁剪 /// </summary> W_HCut = 5, } #endregion
#region Thumbnail
/// <summary> /// 无损压缩图片 /// </summary> /// <param name="sourceFile">原图片</param> /// <param name="stream">压缩后保存到流中</param> /// <param name="height">高度</param> /// <param name="width"></param> /// <param name="quality">压缩质量 1-100</param> /// <param name="type">压缩缩放类型</param> /// <returns></returns> private static Bitmap Thumbnail(string sourceFile, int width, int height, int quality , ImgThumbnailType type, out ImageFormat tFormat) { using (System.Drawing.Image iSource = System.Drawing.Image.FromFile(sourceFile)) { tFormat = iSource.RawFormat; //缩放后的宽度和高度 int toWidth = width; int toHeight = height; // int x = 0; int y = 0; int oWidth = iSource.Width; int oHeight = iSource.Height;
switch (type) { case ImgThumbnailType.WH://指定高宽缩放（可能变形） { break; } case ImgThumbnailType.W://指定宽，高按比例 { toHeight = iSource.Height * width / iSource.Width; break; } case ImgThumbnailType.H://指定高，宽按比例 { toWidth = iSource.Width * height / iSource.Height; break; } case ImgThumbnailType.Cut://指定高宽裁减（不变形） { if ((double)iSource.Width / (double)iSource.Height > (double)toWidth / (double)toHeight) { oHeight = iSource.Height; oWidth = iSource.Height * toWidth / toHeight; y = 0; x = (iSource.Width - oWidth) / 2; } else { oWidth = iSource.Width; oHeight = iSource.Width * height / toWidth; x = 0; y = (iSource.Height - oHeight) / 2; } break; } case ImgThumbnailType.W_HCut://按照宽度成比例缩放后，按照指定的高度进行裁剪 { toHeight = iSource.Height * width / iSource.Width; if (height < toHeight) { oHeight = oHeight * height / toHeight; toHeight = toHeight * height / toHeight; } break; } default: break; }
Bitmap ob = new Bitmap(toWidth, toHeight); //ImgWaterMark iwm = new ImgWaterMark(); //iwm.AddWaterMark(ob, towidth, toheight, "www.****.com"); Graphics g = Graphics.FromImage(ob); g.Clear(System.Drawing.Color.WhiteSmoke); g.CompositingQuality = CompositingQuality.HighQuality; g.SmoothingMode = SmoothingMode.HighQuality; g.InterpolationMode = InterpolationMode.HighQualityBicubic; g.DrawImage(iSource , new Rectangle(x, y, toWidth, toHeight) , new Rectangle(0, 0, oWidth, oHeight) , GraphicsUnit.Pixel); g.Dispose();
return ob; } }
#endregion } }
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转载于:https://www.cnblogs.com/xxj-jing/archive/2012/07/04/2890059.html
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