Asp.Net 上传图片并根据json参数生成缩略图

在asp.net中，上传图片功能或者是常用的，生成缩略图也是常用的

生成图片缩略图帮助类：

public enum ThumbnailMode
{
/// <summary>
/// 指定高宽缩放(可能变形)
/// </summary>
FixedHeightWidth,
/// <summary>
/// 指定宽度,高度按比例自动计算
/// </summary>
WidthBased,
/// <summary>
/// 指定高度,宽度按比例自动计算
/// </summary>
HeightBased,
/// <summary>
/// 指定高宽裁减(从Width,Height处开始裁剪,不变形)
/// </summary>
/// 
KeepAspectRatio,
}

class ImageHelperException : Exception
{
public readonly string ErrorCode;
public ImageHelperException(string errorCode, string message)
: base(message)
{
ErrorCode = errorCode;
}
}
public class ImageHelper
{
public static Image GetThumbnail(Image sourceImage, int width, int height, ThumbnailMode mode)
{
int originalWidth = sourceImage.Width;
int originalHeight = sourceImage.Height;
int thumbnailWidth, thumbnailHeight;
int cropWidth=sourceImage.Width;
int cropHeight=sourceImage.Height;
double ratio;

switch (mode)
{
case ThumbnailMode.FixedHeightWidth:
thumbnailWidth = width;
thumbnailHeight = height;
break;
case ThumbnailMode.WidthBased:
thumbnailWidth = width;
ratio = (double)width / originalWidth;
thumbnailHeight = Convert.ToInt32(originalHeight * ratio);
if (thumbnailHeight == 0) thumbnailHeight = 1;
break;
case ThumbnailMode.HeightBased:
thumbnailHeight = height;
ratio = (double)height / originalHeight;
thumbnailWidth = Convert.ToInt32(originalWidth * ratio);
if (thumbnailWidth == 0) thumbnailWidth = 1;
break;
case ThumbnailMode.KeepAspectRatio:
thumbnailHeight = height;
thumbnailWidth = width;
float thumbRaitio = (float)thumbnailWidth / (float)thumbnailHeight;
float origRatio = (float)originalWidth / (float)originalHeight;
if (thumbRaitio < origRatio)
{
//原图宽
cropWidth = (int)(originalHeight * thumbRaitio);
}
else
{
cropHeight = (int)(originalWidth / thumbRaitio);
//小图宽
}
break;

default:
throw new ImageHelperException("99", "Invalid Thumbnail Mode");
}

Graphics g = null;
try
{
//新建一个bmp图片
Image thumbnail = new Bitmap(thumbnailWidth, thumbnailHeight);

//新建一个画板
g = Graphics.FromImage(thumbnail);

//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
Rectangle rectThumbnail = new Rectangle(0, 0, thumbnailWidth, thumbnailHeight);
Rectangle rectSelection = new Rectangle(0, 0, originalWidth, originalHeight);

if (mode == ThumbnailMode.KeepAspectRatio)
{
rectSelection = new Rectangle((originalWidth - cropWidth) / 2, (originalHeight - cropHeight) / 2, cropWidth, cropHeight);
}

g.DrawImage(sourceImage, rectThumbnail, rectSelection, GraphicsUnit.Pixel);

return thumbnail;
}
finally
{
if (g != null) g.Dispose();
}

}

/// <summary>
/// Get Thumbnail from file
/// </summary>
/// <param name="fileName"></param>
/// <param name="width"></param>
/// <param name="height"></param>
/// <param name="mode"></param>
/// <returns>Image</returns>
public static Image GetThumbnail(string fileName, int width, int height, ThumbnailMode mode)
{
Image img = Image.FromFile(fileName);
return GetThumbnail(img, width, height, mode);
}

/// <summary>
/// Get thumbnail from image and save thumbnail
/// </summary>
/// <param name="sourceImage"></param>
/// <param name="destFileName"></param>
/// <param name="width"></param>
/// <param name="height"></param>
/// <param name="mode"></param>
public static void GetThumbnail(Image sourceImage, string destFileName, int width, int height, ThumbnailMode mode, ImageFormat saveFormat)
{
Image thumbnailcopy = GetThumbnail(sourceImage, width, height, mode);
Image thumbnail = new Bitmap(thumbnailcopy);
thumbnailcopy.Dispose();
try
{
thumbnail.Save(destFileName, saveFormat);
}
finally
{
thumbnail.Dispose();
}
}

/// <summary>
/// Get thumbnail from file and save thumbnail
/// </summary>
/// <param name="sourceFileName">source image file name</param>
/// <param name="destFileName">file name to save thumbnail</param>
/// <param name="width">width of thumbnail</param>
/// <param name="height">height of thumbnail</param>
/// <param name="mode">mode</param>
public static void GetThumbnail(string sourceFileName, string destFileName, int width, int height, ThumbnailMode mode, ImageFormat saveFormat)
{
Image img = Image.FromFile(sourceFileName);
GetThumbnail(img, destFileName, width, height, mode, saveFormat);
}

/// <summary>
/// Get thumbnail with specified region from image
/// </summary>
/// <param name="sourceImage">source image</param>
/// <param name="offsetX">x offset in source image</param>
/// <param name="offsetY">y offset in source image</param>
/// <param name="width">width of thumbnail</param>
/// <param name="height">height of thumbnail</param>
/// <returns></returns>
public static Image GetThumbnail(Image sourceImage, int offsetX, int offsetY, int width, int height)
{
Image thumbnail = new Bitmap(width, height);
Graphics g = null;

try
{
//新建一个画板
g = Graphics.FromImage(thumbnail);

//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
Rectangle rectThumbnail = new Rectangle(0, 0, width, height);
Rectangle rectSelection = new Rectangle(offsetX, offsetY, width, height);
g.DrawImage(sourceImage, rectThumbnail, rectSelection, GraphicsUnit.Pixel);

return thumbnail;
}
finally
{
if (g != null) g.Dispose();
}
}

/// <summary>
/// Get thumbnail with specified region from file
/// </summary>
/// <param name="sourceFileName">source image file name</param>
/// <param name="offsetX">x offset in source image</param>
/// <param name="offsetY">y offset in source image</param>
/// <param name="width">width of thumbnail</param>
/// <param name="height">height of thumbnail</param>
/// <returns></returns>
public static Image GetThumbnail(string sourceFileName, int offsetX, int offsetY, int width, int height)
{
Image img = Image.FromFile(sourceFileName);
return GetThumbnail(img, offsetX, offsetY, width, height);
}

/// <summary>
/// Get thumbnail with specified region from image and save to file
/// </summary>
/// <param name="sourceImage">source image</param>
/// <param name="offsetX">x offset in source image</param>
/// <param name="offsetY">y offset in source image</param>
/// <param name="width">width of thumbnail</param>
/// <param name="height">height of thumbnail</param>
/// <returns></returns>
public static void GetThumbnail(Image sourceImage, string destFileName, int offsetX, int offsetY, int width, int height, ImageFormat saveFormat)
{
Image thumbnail = GetThumbnail(sourceImage, offsetX, offsetY, width, height);

try
{
thumbnail.Save(destFileName, saveFormat);
}
finally
{
thumbnail.Dispose();
}
}

/// <summary>
/// Get thumbnail with specified region from file and save to file
/// </summary>
/// <param name="sourceFileName">source image file name</param>
/// <param name="destFileName">file name to save thumbnail</param>
/// <param name="offsetX">x offset in source image</param>
/// <param name="offsetY">y offset in source image</param>
/// <param name="width">width of thumbnail</param>
/// <param name="height">height of thumbnail</param>
/// <returns></returns>
public static void GetThumbnail(string sourceFileName, string destFileName, int offsetX, int offsetY, int width, int height, ImageFormat saveFormat)
{
Image img = Image.FromFile(sourceFileName);
GetThumbnail(img, destFileName, offsetX, offsetY, width, height, saveFormat);
}


public static void GetImageSize(string fileName, out int width, out int height)
{
Image img = Image.FromFile(fileName);
width = img.Width;
height = img.Height;
}


}

 

 

 

后台代码调用帮助类方法：

try
{
if (this.flUpload.PostedFile.FileName == "")
{
this.cvPage.ErrorMessage = "请选择上传文件";
this.cvPage.IsValid = false;
return;
}
string pPath = ConfigurationManager.AppSettings["UserDataPath"] + "\\Upload\\"; //C:\MyProjects\xframework3.cms\src\XFCMSSln\ExtModuleCMSWeb\UserData\Upload\
string fileName = DateTime.Now.Ticks.ToString();//重新给图片命名
string updFileName = this.flUpload.PostedFile.FileName;//图片名称
string ext = updFileName.Substring(updFileName.LastIndexOf("."));
this.flUpload.PostedFile.SaveAs(pPath + fileName + ext);//保存图片
string originalPath = pPath + fileName + ext;//原图片
int fieldDefinitionId = Convert.ToInt32(Request.QueryString["FieldDefinitionId"]);
FieldDefinitionDao dao = new FieldDefinitionDao(XFMainApplication.Instance.HibSessions);
CMS_FieldDefinition fieldDefinition = dao.GetFieldDefinition("where FieldDefinitionID=" + fieldDefinitionId)[0] as CMS_FieldDefinition;
string ImgResizeParm = fieldDefinition.ImgResizeParm;//参数
string resize = fieldDefinition.IsImgResize; //是否缩略
if (resize == "Y")
{
//string thumbnailfileName;//缩略图片名称
//ImageResizeModel iRm = new ImageResizeModel();
//iRm.ImageResizeParms = JsonConvert.DeserializeObject<List<ImageResizeParm>>(ImgResizeParm);
//ImageResizeModel mdlParm = new ImageResizeModel();
//ImageResizeModel mdlParm = JsonConvert.DeserializeObject<ImageResizeModel>(ImgResizeParm);//转为json对象
ImageResizeModel mdlParm = (ImageResizeModel)JsonConvert.DeserializeObject(ImgResizeParm, typeof(ImageResizeModel));
if (mdlParm.ImageResizeParms != null)//判断集合了里面是否有数据
{
foreach (var item in mdlParm.ImageResizeParms)
{
//thumbnailfileName = DateTime.Now.Ticks.ToString();//循环生成缩略图片名称
string FolderName = item.FolderName;
string thumbnailPuffPath = Path.Combine(pPath, FolderName);//原图片加文件夹名称，缩略图片路径
if (!System.IO.File.Exists(thumbnailPuffPath))
{
Directory.CreateDirectory(thumbnailPuffPath);//创建文件夹
}
string thumbnailPuffPaths = Path.Combine(thumbnailPuffPath, fileName + ext);
int wigth = item.Width;
int hight = item.Height;
ImageHelper.GetThumbnail(originalPath, thumbnailPuffPaths, wigth, hight, ThumbnailMode.KeepAspectRatio, ImageFormat.Jpeg);
}
}
else
{
this.lblmessage.Text = "对象为空";
//Response.Write("<script language='javascript'>alert('对象是空')</script>");
}
}
else
{
this.flUpload.PostedFile.SaveAs(pPath + fileName + ext);//保存图片
}
string vPath = ConfigurationManager.AppSettings["UserDataUrl"] + "/Upload/";//"../System/Upload/";
string script = "<script language='javascript'>window.opener.aspnetForm." + Request.QueryString["fieldName"] + ".value = '" + vPath + fileName + ext + "';window.close();</script>";
Response.Write(script);
}
catch (Newtonsoft.Json.JsonReaderException)
{
this.lblmessage.Text = "Json数据格式不对";
}
catch (Newtonsoft.Json.JsonSerializationException)
{
this.lblmessage.Text = "Json数据格式不对,导致解析不对";
}

catch (Exception ex)
{

this.lblmessage.Text = ex.Message;
//this.Page.ClientScript.RegisterClientScriptBlock(GetType(), "scriptSessionLost", "alert('操作失败，数据格式不正确，请重试!');", true);
}