public static void MakeThumbnail(string ImagePath, int w, int h, string SavePath = "", ThumbnailMode mode = ThumbnailMode.HW)
{
Image originalImage = Image.FromFile(files.MapPath(ImagePath));
int towidth = w;
int toheight = h;
int x = 0;
int y = 0;
int ow = originalImage.Width;
int oh = originalImage.Height;
switch (mode)
{
case ThumbnailMode.HW://指定高宽缩放（可能变形）
break;
case ThumbnailMode.W://指定宽，高按比例
toheight = originalImage.Height * w / originalImage.Width;
break;
case ThumbnailMode.H://指定高，宽按比例
towidth = originalImage.Width * h / 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 * h / 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.High;
//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);
try
{
string imgtype = "";
if (SavePath == "v")
{
using (MemoryStream ms = new MemoryStream())
{
bitmap.Save(ms, Fun.getImageFormat(ImagePath, ref imgtype));
HttpResponse response = HttpContext.Current.Response;
response.ClearContent();
response.ContentType = imgtype;
response.BinaryWrite(ms.ToArray());
}
}
else
{
if (string.IsNullOrEmpty(SavePath))
SavePath = ImagePath.Replace(".", "_small.");
originalImage.Dispose();
bitmap.Save(files.MapPath(SavePath), Fun.getImageFormat(ImagePath, ref imgtype));
}
}
catch (System.Exception e)
{
throw e;
}
finally
{
originalImage.Dispose();
bitmap.Dispose();
g.Dispose();
}
}
/// <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>
public void CreateMinImage(string originalImagePath, string thumbnailPath, int width, int height)
{
System.Drawing.Image originalImage = System.Drawing.Image.FromFile(HttpContext.Current.Server.MapPath(originalImagePath));
int towidth = width;
int toheight = height;
int ow = originalImage.Width;
int oh = originalImage.Height;
//新建一个bmp图片
System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth, toheight);
//新建一个画板
System.Drawing.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));
try
{
//以jpg格式保存缩略图
string FileExt = Path.GetFileNameWithoutExtension(originalImagePath);
//这里报错 bitmap.Save(HttpContext.Current.Server.MapPath(thumbnailPath) + FileExt + ".jpg", System.Drawing.Imaging.ImageFormat.Jpeg);
}
catch (System.Exception e)
{
throw e;
}
finally
{
originalImage.Dispose();
bitmap.Dispose();
g.Dispose();
}
}
//修改后的代码
public void CreateMinImageAndDel(string originalImagePath, string thumbnailPath, int width, int height)
{
Graphics draw = null;
string FileExt = "";
System.Drawing.Image originalImage = System.Drawing.Image.FromFile(HttpContext.Current.Server.MapPath(originalImagePath));
int towidth = width;
int toheight = height;
int ow = originalImage.Width;
int oh = originalImage.Height;
//新建一个bmp图片
System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth, toheight);
System.Drawing.Image bitmap2 = new System.Drawing.Bitmap(towidth, toheight);
//新建一个画板
System.Drawing.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));
try
{
//以jpg格式保存缩略图
FileExt = Path.GetFileNameWithoutExtension(originalImagePath);
//用新建立的image对象拷贝bitmap对象 让g对象可以释放资源
draw = Graphics.FromImage(bitmap2);
draw.DrawImage(bitmap, 0, 0);
}
catch (System.Exception e)
{
throw e;
}
finally
{
originalImage.Dispose();
bitmap.Dispose();
g.Dispose();
//保存调整在这里即可
bitmap2.Save(HttpContext.Current.Server.MapPath(thumbnailPath) + FileExt + ".jpg", System.Drawing.Imaging.ImageFormat.Jpeg);
}
}