图片压缩算法
图片压缩算法
public class ThumbnailMaker
{
//private static ThumbnailMaker instance;
//public static ThumbnailMaker Instance
//{
// get
// {
// lock (typeof(ThumbnailMaker))
// {
// if (instance == null)
// instance = new ThumbnailMaker();
// return instance;
// }
// }
//}
public static void CreateDirectory(string path)
{
if (path == "") return;
string head = path.Substring(0, path.IndexOf("\\")); //d:
string weibu = path.Substring(head.Length + 1); // \1\2
string hpath = head;
while (weibu.IndexOf("\\") != -1)
{
string p = hpath + "\\" + weibu.Substring(0, weibu.IndexOf("\\"));
hpath = p;
if (!Directory.Exists(p))
Directory.CreateDirectory(p);
int ix = weibu.IndexOf("\\") + 1;
weibu = weibu.Substring(ix);
}
}
/// <summary>
/// 制作图片的缩略图
/// </summary>
/// <param name="originalImage">原图</param>
/// <param name="width">缩略图的宽（像素）</param>
/// <param name="height">缩略图的高（像素）</param>
/// <param name="mode">缩略方式</param>
/// <returns>缩略图</returns>
/// <remarks>
/// <paramref name="mode"/>：
/// <para>HW：指定的高宽缩放（可能变形）</para>
/// <para>HWO：指定高宽缩放（可能变形）（过小则不变）</para>
/// <para>W：指定宽，高按比例</para>
/// <para>WO：指定宽（过小则不变），高按比例</para>
/// <para>H：指定高，宽按比例</para>
/// <para>HO：指定高（过小则不变），宽按比例</para>
/// <para>CUT：指定高宽裁减（不变形）</para>
/// </remarks>
public static Image MakeThumbnail(Image originalImage, int width, int height, ThumbnailMode mode)
{
int towidth = width;
int toheight = height;
int x = 0;
int y = 0;
int ow = originalImage.Width;
int oh = originalImage.Height;
switch (mode)
{
case ThumbnailMode.UsrHeightWidth: //指定高宽缩放（可能变形）
break;
case ThumbnailMode.UsrHeightWidthBound: //指定高宽缩放（可能变形）（过小则不变）
if (originalImage.Width <= width && originalImage.Height <= height)
{
return originalImage;
}
if (originalImage.Width < width)
{
towidth = originalImage.Width;
}
if (originalImage.Height < height)
{
toheight = originalImage.Height;
}
break;
case ThumbnailMode.UsrWidth: //指定宽，高按比例
toheight = originalImage.Height * width / originalImage.Width;
break;
case ThumbnailMode.UsrWidthBound: //指定宽（过小则不变），高按比例
if (originalImage.Width <= width)
{
return originalImage;
}
else
{
toheight = originalImage.Height * width / originalImage.Width;
}
break;
case ThumbnailMode.UsrHeight: //指定高，宽按比例
towidth = originalImage.Width * height / originalImage.Height;
break;
case ThumbnailMode.UsrHeightBound: //指定高（过小则不变），宽按比例
if (originalImage.Height <= height)
{
return originalImage;
}
else
{
towidth = originalImage.Width * height / originalImage.Height;
}
break;
case ThumbnailMode.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 Bitmap(towidth, toheight);
//新建一个画板
Graphics g = Graphics.FromImage(bitmap);
//设置高质量插值法
g.InterpolationMode = InterpolationMode.HighQualityBicubic;
//设置高质量,低速度呈现平滑程度
g.SmoothingMode = 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);
g.Dispose();
return bitmap;
}
/// <summary>
/// 制作图片的缩略图
/// </summary>
/// <param name="originalStream">原图</param>
/// <param name="thumbnailPath">保存缩略图的路径</param>
/// <param name="width">缩略图的宽（像素）</param>
/// <param name="height">缩略图的高（像素）</param>
/// <param name="mode">缩略方式，参见<seealso cref="MakeThumbnail(Image, int, int, string)"/></param>
public static void MakeThumbnail(Stream originalStream, string thumbnailPath, int width, int height, ThumbnailMode mode)
{
Image originalImage = Image.FromStream(originalStream);
try
{
MakeThumbnail(originalImage, thumbnailPath, width, height, mode);
}
finally
{
originalImage.Dispose();
}
}
/// <summary>
/// 制作图片的缩略图
/// </summary>
/// <param name="originalImage">原图</param>
/// <param name="thumbnailPath">保存缩略图的路径</param>
/// <param name="width">缩略图的宽（像素）</param>
/// <param name="height">缩略图的高（像素）</param>
/// <param name="mode">缩略方式，参见<seealso cref="MakeThumbnail(Image, int, int, string)"/></param>
public static void MakeThumbnail(Image originalImage, string thumbnailPath, int width, int height, ThumbnailMode mode)
{
Image bitmap = MakeThumbnail(originalImage, width, height, mode);
try
{
//以jpg格式保存缩略图
bitmap.Save(thumbnailPath, ImageFormat.Jpeg);
}
finally
{
bitmap.Dispose();
}
}
/// <summary>
/// 制作图片的缩略图
/// </summary>
/// <param name="originalImagePath">原图的路径</param>
/// <param name="thumbnailPath">保存缩略图的路径</param>
/// <param name="width">缩略图的宽（像素）</param>
/// <param name="height">缩略图的高（像素）</param>
/// <param name="mode">缩略方式，参见<seealso cref="MakeThumbnail(Image, int, int, string)"/></param>
public static void MakeThumbnail(string originalImagePath, string thumbnailPath, int width, int height, ThumbnailMode mode)
{
Image originalImage = Image.FromFile(originalImagePath);
try
{
MakeThumbnail(originalImage, thumbnailPath, width, height, mode);
}
finally
{
originalImage.Dispose();
}
}
/// <summary>
///
/// </summary>
/// <param name="img"></param>
/// <param name="width"></param>
/// <param name="height"></param>
/// <param name="mode"></param>
public static byte[] MakeThumbnail(byte[] img, int width, int height, ThumbnailMode mode)
{
Stream byteStream = new MemoryStream(img);
Image originalImage = Image.FromStream(byteStream);
try
{
Image _img = MakeThumbnail(originalImage, width, height, mode);
MemoryStream imgStream = new MemoryStream();
_img.Save(imgStream, ImageFormat.Jpeg);
return imgStream.ToArray();
}
finally
{
originalImage.Dispose();
}
}
/// <summary>
/// 产生高清缩略图 固定大小
/// </summary>
/// <param name="original_image_file">源文件</param>
/// <param name="object_width">缩略图宽度</param>
/// <param name="object_height">缩略图高度</param>
public static void MakeHighQualityThumbnail(string original_image_file, string output, int object_width, int object_height)
{
int actual_width = 0;
int actual_heigh = 0;
string outputfilename = output; //original_image_file + ".jpg";
System.Drawing.Bitmap original_image = new Bitmap(original_image_file);//读取源文件
actual_width = original_image.Width;
actual_heigh = original_image.Height;
Bitmap img = new Bitmap(object_width, object_height);
img.SetResolution(108f, 108f);
Graphics gdiobj = Graphics.FromImage(img);
gdiobj.CompositingQuality = CompositingQuality.HighQuality;
gdiobj.SmoothingMode = SmoothingMode.HighQuality;
gdiobj.InterpolationMode = InterpolationMode.HighQualityBicubic;
gdiobj.PixelOffsetMode = PixelOffsetMode.HighQuality;
gdiobj.FillRectangle(new SolidBrush(Color.White), 0, 0, object_width, object_height);
Rectangle destrect = new Rectangle(0, 0, object_width, object_height);
gdiobj.DrawImage(original_image, destrect, 0, 0, actual_width, actual_heigh, GraphicsUnit.Pixel);
System.Drawing.Imaging.EncoderParameters ep = new System.Drawing.Imaging.EncoderParameters(1);
ep.Param[0] = new System.Drawing.Imaging.EncoderParameter(System.Drawing.Imaging.Encoder.Quality, (long)100);
System.Drawing.Imaging.ImageCodecInfo ici = System.Drawing.Imaging.ImageCodecInfo.GetImageEncoders()[0];
if (ici != null)
{
if (File.Exists(outputfilename))
File.Delete(outputfilename);
img.Save(outputfilename, ici, ep);
}
else
{
img.Save(outputfilename, System.Drawing.Imaging.ImageFormat.Jpeg);
}
}
/// <summary>
///
/// </summary>
/// <param name="img"></param>
/// <param name="width"></param>
/// <param name="height"></param>
/// <param name="mode"></param>
public static byte[] MakeThumbnail(byte[] img, int width, int height)
{
return MakeThumbnail(img, width, height, ThumbnailMode.UsrHeightBound);
}
}
//<para>HW：指定的高宽缩放（可能变形）</para>
//<para>HWO：指定高宽缩放（可能变形）（过小则不变）</para>
//<para>W：指定宽，高按比例</para>
//<para>WO：指定宽（过小则不变），高按比例</para>
//<para>H：指定高，宽按比例</para>
//<para>HO：指定高（过小则不变），宽按比例</para>
//<para>CUT：指定高宽裁减（不变形）</para>
public enum ThumbnailMode
{
UsrHeightWidth,
UsrHeightWidthBound,
UsrWidth,
UsrWidthBound,
UsrHeight,
UsrHeightBound,
Cut,
NONE,
}
转载自：http://q.cnblogs.com/q/44414/
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