写了一个缩放图片的类，但是缩放过后，要比原图文件大小大很多（原图300KB，缩略图512KB）
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[已关闭问题]
关闭于 2013-01-09 15:06
1 using System; 2 using System.Drawing; 3 using System.Drawing.Drawing2D; 4 using System.Drawing.Imaging; 5 using System.IO; 6 using ImageManipulation; 7 8 namespace Zz.Common 9 { 10 11 12 public class ImageHelper 13 { 14 15 public class WatermarkTRBL 16 { 17 public WatermarkTRBL() 18 { 19 20 } 21 int? top = null, right = null, bottom = null, left = null; 22 public WatermarkTRBL(int? top, int? right, int? bottom, int? left) 23 { 24 this.top = top; 25 this.right = right; 26 this.bottom = bottom; 27 this.left = left; 28 } 29 30 public int? Top 31 { 32 get { return top; } 33 set { top = value; } 34 } 35 public int? Right 36 { 37 get { return right; } 38 set { right = value; } 39 } 40 41 public int? Bottom 42 { 43 get { return bottom; } 44 set { bottom = value; } 45 } 46 47 public int? Left 48 { 49 get { return left; } 50 set { left = value; } 51 } 52 } 53 54 55 /// <summary> 56 /// 给图片加水印 57 /// </summary> 58 /// <param name="originalImg"></param> 59 /// <param name="waterImg"></param> 60 /// <param name="trbl"></param> 61 /// <returns></returns> 62 public static Image WatermarkImage(Image originalImg, Image waterImg, WatermarkTRBL trbl) 63 { 64 65 Image image = (Image)originalImg.Clone(); 66 using (Graphics g = Graphics.FromImage(image)) 67 { 68 Rectangle r = new Rectangle(); 69 r.Height = waterImg.Height; 70 r.Width = waterImg.Width; 71 if (trbl.Top != null) 72 { 73 r.Y = (int)trbl.Top; 74 } 75 76 if (trbl.Right != null) 77 { 78 r.X = originalImg.Width - waterImg.Width - (int)trbl.Right; 79 } 80 81 if (trbl.Bottom != null) 82 { 83 r.Y = originalImg.Height - waterImg.Height - (int)trbl.Bottom; 84 } 85 86 if (trbl.Left != null) 87 { 88 r.X = (int)trbl.Left; 89 } 90 91 g.DrawImage(waterImg, r, 0, 0, waterImg.Width, waterImg.Height, GraphicsUnit.Pixel); 92 } 93 94 return image; 95 } 96 97 98 99 /// <summary> 100 /// 等比缩放图片 101 /// </summary> 102 /// <param name="imgPhoto"></param> 103 /// <param name="width"></param> 104 /// <param name="height"></param> 105 /// <returns></returns> 106 public static System.Drawing.Image GetImageThumbnail(System.Drawing.Image imgPhoto, int width, int height) 107 { 108 109 int sourceWidth = imgPhoto.Width; 110 int sourceHeight = imgPhoto.Height; 111 112 113 //int x, y; //位置 114 int w, h; //缩放后的宽和高 115 116 if (sourceWidth > width || sourceHeight > height) 117 { 118 decimal wPercent = (decimal)sourceWidth / width; 119 decimal hPercent = (decimal)sourceHeight / height; 120 decimal nPercent; 121 if (hPercent > wPercent) 122 { 123 nPercent = hPercent; 124 } 125 else 126 { 127 nPercent = wPercent; 128 } 129 130 w = (int)Math.Round(sourceWidth / nPercent, 0); 131 h = (int)Math.Round(sourceHeight / nPercent, 0); 132 133 134 135 } 136 else 137 { 138 w = sourceWidth; 139 h = sourceHeight; 140 } 141 142 143 144 145 try 146 { 147 148 Bitmap bmPhoto = new Bitmap(w, h, PixelFormat.Format24bppRgb); 149 bmPhoto.SetResolution(imgPhoto.HorizontalResolution, imgPhoto.VerticalResolution); 150 Graphics grPhoto = Graphics.FromImage(bmPhoto); 151 grPhoto.Clear(Color.White); 152 grPhoto.InterpolationMode = InterpolationMode.HighQualityBicubic; 153 154 grPhoto.DrawImage(imgPhoto, 155 new Rectangle(0, 0, w, h),///它指定所绘制图像的位置和大小。 156 new Rectangle(0, 0, sourceWidth, sourceHeight),///它指定 image 对象中要绘制的部分。 157 GraphicsUnit.Pixel);///它指定 srcRect 参数所用的度量单位。 158 159 grPhoto.Dispose(); 160 161 if (imgPhoto.RawFormat == ImageFormat.Gif || imgPhoto.RawFormat.Guid == ImageFormat.Gif.Guid) 162 { 163 OctreeQuantizer quantizer = new OctreeQuantizer(255, 8); 164 using (Bitmap quantized = quantizer.Quantize(imgPhoto)) 165 { 166 return quantized; 167 } 168 } 169 else 170 { 171 return bmPhoto; 172 } 173 174 } 175 catch 176 { 177 178 return null; 179 } 180 } 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 public static System.Drawing.Image GetImageThumbnail(System.Drawing.Image imgPhoto, int width) 199 { 200 201 int sourceWidth = imgPhoto.Width; 202 int sourceHeight = imgPhoto.Height; 203 204 205 //int x, y; //位置 206 int w, h; //缩放后的宽和高 207 208 if (sourceWidth > width) 209 { 210 decimal nPercent = (decimal)sourceWidth / width; 211 w = (int)Math.Round(sourceWidth / nPercent, 0); 212 h = (int)Math.Round(sourceHeight / nPercent, 0); 213 } 214 else 215 { 216 w = sourceWidth; 217 h = sourceHeight; 218 } 219 220 221 try 222 { 223 Bitmap bmPhoto = new Bitmap(w, h, PixelFormat.Format24bppRgb); 224 bmPhoto.SetResolution(imgPhoto.HorizontalResolution, imgPhoto.VerticalResolution); 225 Graphics grPhoto = Graphics.FromImage(bmPhoto); 226 grPhoto.Clear(Color.White); 227 grPhoto.InterpolationMode = InterpolationMode.HighQualityBicubic; 228 229 grPhoto.DrawImage(imgPhoto, 230 new Rectangle(0, 0, w, h),///它指定所绘制图像的位置和大小。 231 new Rectangle(0, 0, sourceWidth, sourceHeight),///它指定 image 对象中要绘制的部分。 232 GraphicsUnit.Pixel);///它指定 srcRect 参数所用的度量单位。 233 234 grPhoto.Dispose(); 235 236 if (imgPhoto.RawFormat == ImageFormat.Gif || imgPhoto.RawFormat.Guid == ImageFormat.Gif.Guid) 237 { 238 OctreeQuantizer quantizer = new OctreeQuantizer(255, 8); 239 return quantizer.Quantize(bmPhoto); 240 } 241 else 242 { 243 return bmPhoto; 244 } 245 246 } 247 catch 248 { 249 250 return null; 251 } 252 } 253 254 255 256 257 258 259 260 public static System.Drawing.Image GetZipImageThumbnail(System.Drawing.Image imgPhoto, int width, int height, int flag) 261 { 262 Image thumbnail = GetImageThumbnail(imgPhoto, width, height); 263 return ZipImage(thumbnail, flag); 264 } 265 266 267 public static System.Drawing.Image GetZipImageThumbnail(System.Drawing.Image imgPhoto, int width, int flag) 268 { 269 Image thumbnail = GetImageThumbnail(imgPhoto, width); 270 return ZipImage(thumbnail, flag); 271 272 } 273 274 275 276 277 278 279 280 281 /// <summary> 282 /// 压缩图片 283 /// </summary> 284 /// <param name="imgPhoto"></param> 285 /// <param name="flag"></param> 286 /// <returns></returns> 287 public static System.Drawing.Image ZipImage(System.Drawing.Image imgPhoto, int flag) 288 { 289 EncoderParameters ep = new EncoderParameters(); 290 long[] qy = new long[1]; 291 qy[0] = flag;//设置压缩的比例1-100 292 EncoderParameter eParam = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, qy); 293 ep.Param[0] = eParam; 294 295 try 296 { 297 ImageCodecInfo[] arrayICI = ImageCodecInfo.GetImageEncoders(); 298 ImageCodecInfo jpegICIinfo = null; 299 for (int x = 0; x < arrayICI.Length; x++) 300 { 301 if (arrayICI[x].FormatDescription.Equals("JPEG")) 302 { 303 jpegICIinfo = arrayICI[x]; 304 break; 305 } 306 } 307 308 MemoryStream ms = new MemoryStream(); 309 310 311 if (jpegICIinfo != null) 312 { 313 314 imgPhoto.Save(ms, jpegICIinfo, ep);//dFile是压缩后的新路径 315 } 316 else 317 { 318 imgPhoto.Save(ms, imgPhoto.RawFormat); 319 } 320 321 System.Drawing.Image zipImage = System.Drawing.Image.FromStream(ms); 322 return zipImage; 323 } 324 catch 325 { 326 return null; 327 } 328 } 329 330 331 } 332 }
帮我看看代码哪里出了问题？？
所有回答(2)
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public bool ThumbnailCallback() { return false; } public void Example_GetThumb(PaintEventArgs e) { Image.GetThumbnailImageAbort myCallback = new Image.GetThumbnailImageAbort(ThumbnailCallback); Bitmap myBitmap = new Bitmap("Climber.jpg"); Image myThumbnail = myBitmap.GetThumbnailImage( 40, 40, myCallback, IntPtr.Zero); e.Graphics.DrawImage(myThumbnail, 150, 75); }
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果断给你粘个方法过来看看能不能帮到你,
#region 生成缩略图
///<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 void MakeThumbnail(string originalImagePath, string thumbnailPath, int width, int height, string mode, string type)
{
System.Drawing.Image originalImage = System.Drawing.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
System.Drawing.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(System.Drawing.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 System.Drawing.Rectangle(0, 0, towidth, toheight), new System.Drawing.Rectangle(x, y, ow, oh), GraphicsUnit.Pixel);
try
{
System.Drawing.Imaging.ImageFormat imgtype = System.Drawing.Imaging.ImageFormat.Jpeg;
if (type == "png")
{
imgtype = System.Drawing.Imaging.ImageFormat.Png;
}
if (type == "jpg")
{
imgtype = System.Drawing.Imaging.ImageFormat.Jpeg;
}
//保存缩略图
bitmap.Save(thumbnailPath, imgtype);
}
catch (System.Exception e)
{
throw e;
}
finally
{
originalImage.Dispose();
bitmap.Dispose();
g.Dispose();
}
}
#endregion
我写的一个修改图片大小的小工具,原文地址给你