.net缩略图的问题~~~~~~~~~~~~~~~~~求高手赐教!

如下代码有待验证
private static string strConnect = System.Configuration.ConfigurationManager.AppSettings["connStr"];
    //上传图像
    protected void btnUpload_Click(object sender, EventArgs e)
    {
        ……
        string imgType;
        string fullFileName = this.txtPath.PostedFile.FileName;
        imgType = fullFileName.Substring(fullFileName.LastIndexOf(".") + 1).ToLower();
        string UserDirectory = Session["UserID"].ToString();//用户ID为所创建文件夹的名字
        string UserPath = Server.MapPath("UpLoad").ToString() + "\\" + UserDirectory;
        //如果文件夹不存在则创建
        if (!Directory.Exists(UserPath))
        {
            Directory.CreateDirectory(UserPath);
        }
        string originalImagePath = UserPath + "\\" + "Original";
        if(!Directory.Exists(originalImagePath))
        {
            Directory.CreateDirectory(originalImagePath);
        }
        string thumbnailPath = UserPath + "\\" + "Thumbnail";
        if (!Directory.Exists(thumbnailPath))
        {
            Directory.CreateDirectory(thumbnailPath);
        }
        // 获取上传图像的文件名
        string fileName = txtName.Text;
        ……
            if (imgType=="jpg"||imgType=="jpeg"||imgType=="bmp"||imgType=="png"||imgType=="icon")
            {
                try
                {
                    //生成原图
                    byte[] oFileByte = new byte[this.txtPath.PostedFile.ContentLength];
                    Stream oStream = this.txtPath.PostedFile.InputStream;
                    System.Drawing.Image oImage = System.Drawing.Image.FromStream(oStream);
                    int oWidth = oImage.Width;//原图宽度
                    int oHeight = oImage.Height;//原图高度
                    int tWidth = 100;//设置缩略图初始宽度
                    int tHeight = 100;//设置缩略图初始宽度                    //按比例计算出缩略图的宽度和高度
                    if (oWidth >= oHeight)
                    {
                        tHeight = (int)Math.Floor(Convert.ToDouble(oHeight) * (Convert.ToDouble(tWidth) / Convert.ToDouble(oHeight)));
                    }
                    else
                    {
                        tWidth = (int)Math.Floor(Convert.ToDouble(oWidth) * (Convert.ToDouble(tHeight) / Convert.ToDouble(oHeight)));
                    }

                    //生成缩略图
                    Bitmap tImage = new Bitmap(tWidth,tHeight);
                    Graphics g = Graphics.FromImage(tImage);
                    g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;//设置高质量插值法
                    g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;//设置高质量，低速度呈现平滑程度
                    g.Clear(Color.Transparent);//清空画布并以透明背景色填充
                    g.DrawImage(oImage, new Rectangle(0, 0, tWidth, tHeight), new Rectangle(0, 0, oWidth, oHeight), GraphicsUnit.Pixel);

                    //this.txtPath.PostedFile.SaveAs(originalImagePath + "\\" + fileName + "." + imgType);
                    //string originalImageUrl = "UpLoad/" + UserDirectory + "/" + "Orginal/"+fileName + ".jpg" ;//得到服务端原图片的虚拟路径
                    // string thumbnailImageUrl = "UpLoad/" + UserDirectory + "/" + "Thumbnail/" + fileName + ".jpg";//得到服务端原图片的虚拟路径
                    //以JPG格式保存图像
                    //oImage.Save(originalImageUrl, System.Drawing.Imaging.ImageFormat.Jpeg);/*看看这里这两个保存方式有没有问题*/
                  //   tImage.Save(thumbnailImageUrl, System.Drawing.Imaging.ImageFormat.Jpeg);
                    string oPath = originalImagePath + "\\" + fileName + ".jpg";
                    string tPath = thumbnailPath + "\\" + fileName + ".jpg";
                    //以JPG格式保存图像
                    oImage.Save(oPath, System.Drawing.Imaging.ImageFormat.Jpeg);
                    tImage.Save(tPath, System.Drawing.Imaging.ImageFormat.Jpeg);
                    lblMessage.Visible = true;
                    lblMessage.Text = "图像上传成功！";
                    txtName.Text = "";
                    txtDescription.Text = "";
                    //释放资源
                    oImage.Dispose();
                    g.Dispose();
                    tImage.Dispose();
                }
                catch (Exception ex)
                {
                    lblMessage.Visible = true;
                    lblMessage.Text = "由于网络原因，上载文件错误 " + ex.Message;
                }
            }
            else
            {
                Response.Write("<script language='javascript'>alert('你选择的图像格式错误！');</script>");
                lblMessage.Visible = false;
            }
}

搜下吧。有很多相关的资料。http://hi.baidu.com/jonesvale/blog/item/47ab801197909e08213f2e92.html

如下代码有待验证ToThumbnailImage.aspx<%@ Page language="c#" Codebehind="ToThumbnailImage.aspx.cs" Src="ToThumbnailImage.aspx.cs" AutoEventWireup="false" Inherits="Exam_C.ToThumbnailImage" %><html> <head> <title>Lion互动网络 =>生成缩略图</title> </head> <body> <form id="Form1" method="post" runat="server"> </form> </body></html> ToThumbnailImage.aspx.csusing System;using System.Collections;using System.ComponentModel;using System.Data;using System.Drawing;using System.Web;using System.Web.SessionState;using System.Web.UI;using System.Web.UI.WebControls;using System.Web.UI.HtmlControls;using System.Drawing.Imaging;namespace Exam_C{ /// <summary> /// ToThumbnailImage 的摘要说明。 /// </summary> public class ToThumbnailImage : System.Web.UI.Page { /* Create By lion 2003-05-20 19:00 Copyright (C) 2004 www.LionSky.Net. All rights reserved. Web: http://www.Lionsky.net ; Email: [email protected] */ static Hashtable htmimes=new Hashtable(); internal readonly string AllowExt = ".jpe|.jpeg|.jpg|.png|.tif|.tiff|.bmp"; #region Web 窗体设计器生成的代码 override protected void OnInit(EventArgs e) { #region htmimes[".jpe"]="image/jpeg"; htmimes[".jpeg"]="image/jpeg"; htmimes[".jpg"]="image/jpeg"; htmimes[".png"]="image/png"; htmimes[".tif"]="image/tiff"; htmimes[".tiff"]="image/tiff"; htmimes[".bmp"]="image/bmp"; #endregion //调用生成缩略图方法 ToThumbnailImages("lionsky.jpg","b.gif",300); } #endregion #region Helper /// <summary> /// 获取图像编码解码器的所有相关信息 /// </summary> /// <param name="mimeType">包含编码解码器的多用途网际邮件扩充协议 (MIME) 类型的字符串</param> /// <returns>返回图像编码解码器的所有相关信息</returns> static ImageCodecInfo GetCodecInfo(string mimeType) { ImageCodecInfo[] CodecInfo = ImageCodecInfo.GetImageEncoders(); foreach(ImageCodecInfo ici in CodecInfo) { if(ici.MimeType == mimeType)return ici; } return null; } /// <summary> /// 检测扩展名的有效性 /// </summary> /// <param name="sExt">文件名扩展名</param> /// <returns>如果扩展名有效,返回true,否则返回false.</returns> bool CheckValidExt(string sExt) { bool flag=false; string[] aExt = AllowExt.Split('|'); foreach(string filetype in aExt) { if(filetype.ToLower()==sExt) { flag = true; break; } } return flag; } /// <summary> /// 保存图片 /// </summary> /// <param name="image">Image 对象</param> /// <param name="savePath">保存路径</param> /// <param name="ici">指定格式的编解码参数</param> void SaveImage(System.Drawing.Image image,string savePath,ImageCodecInfo ici) { //设置原图片对象的 EncoderParameters 对象 EncoderParameters parameters = new EncoderParameters(1); parameters.Param[0] = new EncoderParameter(Encoder.Quality, ((long) 90)); image.Save(savePath, ici, parameters); parameters.Dispose(); } #endregion #region Methods /// <summary> /// 生成缩略图 /// </summary> /// <param name="sourceImagePath">原图片路径(相对路径)</param> /// <param name="thumbnailImagePath">生成的缩略图路径,如果为空则保存为原图片路径(相对路径)</param> /// <param name="thumbnailImageWidth">缩略图的宽度（高度与按源图片比例自动生成）</param> public void ToThumbnailImages(string sourceImagePath,string thumbnailImagePath,int thumbnailImageWidth) { string SourceImagePath = sourceImagePath; string ThumbnailImagePath = thumbnailImagePath; int ThumbnailImageWidth = thumbnailImageWidth; string sExt = SourceImagePath.Substring(SourceImagePath.LastIndexOf(".")).ToLower(); if(SourceImagePath.ToString()==System.String.Empty) throw new NullReferenceException("SourceImagePath is null!"); if(!CheckValidExt(sExt)) { throw new ArgumentException("原图片文件格式不正确,支持的格式有[ "+ AllowExt +" ]","SourceImagePath"); } //从原图片创建 Image 对象 System.Drawing.Image image = System.Drawing.Image.FromFile(HttpContext.Current.Server.MapPath(SourceImagePath)); int num = ((ThumbnailImageWidth / 4) * 3); int width = image.Width; int height = image.Height; //计算图片的比例 if ((((double) width) / ((double) height)) >= 1.3333333333333333f) { num = ((height * ThumbnailImageWidth) / width); } else { ThumbnailImageWidth = ((width * num) / height); } if ((ThumbnailImageWidth < 1) || (num < 1)) { return; } //用指定的大小和格式初始化 Bitmap 类的新实例 Bitmap bitmap = new Bitmap(ThumbnailImageWidth, num, PixelFormat.Format32bppArgb); //从指定的 Image 对象创建新 Graphics 对象 Graphics graphics = Graphics.FromImage(bitmap); //清除整个绘图面并以透明背景色填充 graphics.Clear(Color.Transparent); //在指定位置并且按指定大小绘制原图片对象 graphics.DrawImage(image, new Rectangle(0, 0, ThumbnailImageWidth, num)); image.Dispose(); try { //将此原图片以指定格式并用指定的编解码参数保存到指定文件 string savepath = (ThumbnailImagePath==null?SourceImagePath:ThumbnailImagePath); SaveImage(bitmap,HttpContext.Current.Server.MapPath(savepath),GetCodecInfo((string)htmimes[sExt])); } catch(System.Exception e) { throw e; } finally { bitmap.Dispose(); graphics.Dispose(); } } #endregion }}

   Bitmap myimage = new Bitmap("D:\\123.jpg");
        myimage.GetThumbnailImage(120, 120, null, IntPtr.Zero);
        //Graphics g = Graphics.FromImage(myimage);
        myimage.Save("E:\\123.gif", System.Drawing.Imaging.ImageFormat.Gif);
为什么图片没缩小呢？   GetThumbnailImage(120, 120, null, IntPtr.Zero);
不是已经制定120了么  为什么存入E盘的文件还是原来那么大呢？

新建一个bitmap是想要的大小。再循环取相应的象素。using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;namespace Image
{
/// <summary>
/// Form1 的摘要说明。
/// </summary>
public class Form1 : System.Windows.Forms.Form
{
private System.Windows.Forms.Button button1;
private System.Windows.Forms.OpenFileDialog openFileDialog1;
/// <summary>
/// 必需的设计器变量。
/// </summary>
private System.ComponentModel.Container components = null;
private System.Windows.Forms.Button button2;
private System.Windows.Forms.NumericUpDown numericUpDown1;
private System.Windows.Forms.Label label1;
private System.Windows.Forms.Label label2;
private System.Windows.Forms.NumericUpDown numericUpDown2;
private System.String StrFileName="";
public Form1()
{
//
// Windows 窗体设计器支持所必需的
//
InitializeComponent(); //
// TODO: 在 InitializeComponent 调用后添加任何构造函数代码
//
} /// <summary>
/// 清理所有正在使用的资源。
/// </summary>
protected override void Dispose( bool disposing )
{
if( disposing )
{
if (components != null)
{
components.Dispose();
}
}
base.Dispose( disposing );
} #region Windows 窗体设计器生成的代码
/// <summary>
/// 设计器支持所需的方法 - 不要使用代码编辑器修改
/// 此方法的内容。
/// </summary>
private void InitializeComponent()
{
this.button1 = new System.Windows.Forms.Button();
this.openFileDialog1 = new System.Windows.Forms.OpenFileDialog();
this.button2 = new System.Windows.Forms.Button();
this.numericUpDown1 = new System.Windows.Forms.NumericUpDown();
this.label1 = new System.Windows.Forms.Label();
this.label2 = new System.Windows.Forms.Label();
this.numericUpDown2 = new System.Windows.Forms.NumericUpDown();
((System.ComponentModel.ISupportInitialize)(this.numericUpDown1)).BeginInit();
((System.ComponentModel.ISupportInitialize)(this.numericUpDown2)).BeginInit();
this.SuspendLayout();
//
// button1
//
this.button1.Location = new System.Drawing.Point(24, 208);
this.button1.Name = "button1";
this.button1.Size = new System.Drawing.Size(80, 23);
this.button1.TabIndex = 0;
this.button1.Text = "浏览图像";
this.button1.Click += new System.EventHandler(this.button1_Click);
//
// openFileDialog1
//
this.openFileDialog1.Filter = "Image files (JPeg, Gif, Bmp, etc.)|*.jpg;*.jpeg;*.gif;*.bmp;*.tif; *.tiff; *.png|" +
" JPeg files (*.jpg;*.jpeg)|*.jpg;*.jpeg |GIF files (*.gif)|*.gif |BMP files (*.b" +
"mp)|*.bmp|Tiff files (*.tif;*.tiff)|*.tif;*.tiff|Png files (*.png)| *.png |All f" +
"iles (*.*)|*.*";
//
// button2
//
this.button2.FlatStyle = System.Windows.Forms.FlatStyle.Popup;
this.button2.Location = new System.Drawing.Point(8, 8);
this.button2.Name = "button2";
this.button2.Size = new System.Drawing.Size(360, 192);
this.button2.TabIndex = 1;
this.button2.Paint += new System.Windows.Forms.PaintEventHandler(this.button2_Paint);
//
// numericUpDown1
//
this.numericUpDown1.Location = new System.Drawing.Point(184, 208);
this.numericUpDown1.Minimum = new System.Decimal(new int[] {
   1,
   0,
   0,
   0});
this.numericUpDown1.Name = "numericUpDown1";
this.numericUpDown1.Size = new System.Drawing.Size(40, 21);
this.numericUpDown1.TabIndex = 2;
this.numericUpDown1.Value = new System.Decimal(new int[] {
5,
0,
0,
0});
this.numericUpDown1.ValueChanged += new System.EventHandler(this.numericUpDown1_ValueChanged);
//
// label1
//
this.label1.Location = new System.Drawing.Point(112, 212);
this.label1.Name = "label1";
this.label1.Size = new System.Drawing.Size(72, 16);
this.label1.TabIndex = 3;
this.label1.Text = "X方向缩放：";
//
// label2
//
this.label2.Location = new System.Drawing.Point(232, 212);
this.label2.Name = "label2";
this.label2.Size = new System.Drawing.Size(72, 16);
this.label2.TabIndex = 5;
this.label2.Text = "Y方向缩放：";
//
// numericUpDown2
//
this.numericUpDown2.Location = new System.Drawing.Point(304, 208);
this.numericUpDown2.Minimum = new System.Decimal(new int[] {
   1,
   0,
   0,
   0});
this.numericUpDown2.Name = "numericUpDown2";
this.numericUpDown2.Size = new System.Drawing.Size(48, 21);
this.numericUpDown2.TabIndex = 4;
this.numericUpDown2.Value = new System.Decimal(new int[] {
5,
0,
0,
0});
this.numericUpDown2.ValueChanged += new System.EventHandler(this.numericUpDown2_ValueChanged);
//
// Form1
//
this.AutoScaleBaseSize = new System.Drawing.Size(6, 14);
this.ClientSize = new System.Drawing.Size(376, 238);
this.Controls.Add(this.label2);
this.Controls.Add(this.numericUpDown2);
this.Controls.Add(this.label1);
this.Controls.Add(this.numericUpDown1);
this.Controls.Add(this.button2);
this.Controls.Add(this.button1);
this.MaximizeBox = false;
this.Name = "Form1";
this.StartPosition = System.Windows.Forms.FormStartPosition.CenterScreen;
this.Text = "演示以任意比例缩放显示图像";
((System.ComponentModel.ISupportInitialize)(this.numericUpDown1)).EndInit();
((System.ComponentModel.ISupportInitialize)(this.numericUpDown2)).EndInit();
this.ResumeLayout(false); }
#endregion /// <summary>
/// 应用程序的主入口点。
/// </summary>
[STAThread]
static void Main()
{
Application.Run(new Form1());
}
private void button1_Click(object sender, System.EventArgs e)
{//浏览图像
           this.openFileDialog1.ShowDialog();
   this.StrFileName=this.openFileDialog1.FileName;
   this.button2.Refresh();
}
private void button2_Paint(object sender, System.Windows.Forms.PaintEventArgs e)
{//以任意比例缩放显示图像
if(this.StrFileName.Trim()=="")
return;
System.Drawing.Bitmap MyBitmap=new Bitmap(this.StrFileName);
Graphics g = e.Graphics;
TextureBrush MyBrush = new TextureBrush(MyBitmap);
float fx=(float)(this.numericUpDown1.Value/10);
float fy=(float)(this.numericUpDown2.Value/10);
g.ScaleTransform(fx,fy);
//MyBrush.ScaleTransform(fx,fy);
g.FillRectangle(MyBrush,0,0,this.ClientRectangle.Width,this.ClientRectangle.Height);
} private void numericUpDown1_ValueChanged(object sender, System.EventArgs e)
{//更新图像显示
this.button2.Refresh();
} private void numericUpDown2_ValueChanged(object sender, System.EventArgs e)
{//更新图像显示
   this.button2.Refresh();
}

}
}

public bool ResizeImg(string ImgFile, string sImgPath, int ResizeWidth, int ResizeHeight, string BgColor)
    {
        try
        {
            FileStream fs = new FileStream(ImgFile, FileMode.Open);
            BinaryReader br = new BinaryReader(fs);
            byte[] bytes = br.ReadBytes((int)fs.Length);
            br.Close();
            fs.Close();
            MemoryStream ms = new MemoryStream(bytes);            System.Drawing.Image imgPhoto = System.Drawing.Image.FromStream(ms);
            int imgPhotoWidth = imgPhoto.Width;
            int imgPhotoHeight = imgPhoto.Height;
            int StartX = 0;
            int StartY = 0;
            int NewWidth = imgPhotoWidth;
            int NewHeight = imgPhotoHeight;
            if (NewWidth > ResizeWidth)
            {
                NewWidth = ResizeWidth;
                NewHeight = Convert.ToInt32(imgPhotoHeight * Math.Round(Convert.ToDecimal(NewWidth) / Convert.ToDecimal(imgPhotoWidth), 10));
            }            if (NewHeight > ResizeHeight)
            {
                NewHeight = ResizeHeight;
                NewWidth = Convert.ToInt32(imgPhotoWidth * Math.Round(Convert.ToDecimal(NewHeight) / Convert.ToDecimal(imgPhotoHeight), 10));
            }            StartX = ResizeWidth - NewWidth;
            StartY = ResizeHeight - NewHeight;            StartX = StartX > 0 ? StartX / 2 : 0;
            StartY = StartY > 0 ? StartY / 2 : 0;            Bitmap bmPhoto = new Bitmap(ResizeWidth, ResizeHeight, System.Drawing.Imaging.PixelFormat.Format24bppRgb);
            bmPhoto.SetResolution(72, 72);
            Graphics gbmPhoto = Graphics.FromImage(bmPhoto);
            gbmPhoto.Clear(Color.FromName(BgColor));
            gbmPhoto.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
            gbmPhoto.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;            gbmPhoto.DrawImage(imgPhoto, new Rectangle(StartX, StartY, NewWidth, NewHeight), new Rectangle(0, 0, imgPhotoWidth, imgPhotoHeight), GraphicsUnit.Pixel);
            bmPhoto.Save(sImgPath, System.Drawing.Imaging.ImageFormat.Jpeg);            imgPhoto.Dispose();
            gbmPhoto.Dispose();
            bmPhoto.Dispose();            return true;
        }
        catch (Exception err)
        {
            return false;
        }
    }
public static void MakeThumbnail(string originalImagePath, string thumbnailPath, int width, int height, string mode)
        {
            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":
                    break;
                case "W":
                    toheight = originalImage.Height * width / originalImage.Width;
                    break;
                case "H":
                    towidth = originalImage.Width * height / originalImage.Height;
                    break;
                case "Cut":
                 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;
            }
           System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth, toheight);
            System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap);
            g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
            g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
            g.Clear(System.Drawing.Color.Transparent);
     g.DrawImage(originalImage, new System.Drawing.Rectangle(0, 0, towidth, toheight),
                new System.Drawing.Rectangle(x, y, ow, oh),
                System.Drawing.GraphicsUnit.Pixel);
            try
            {
                bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg);
            }
            catch (System.Exception e)
            {
                throw e;
            }
            finally
            {
                originalImage.Dispose();
                bitmap.Dispose();
                g.Dispose();
            }        }

System.Drawing.Image image;
image = CommonCreateThumbnailImage.CreateThumbnailImage(图片宽, 高, 路径, null, true, CommonCreateThumbnailImage.ImageMode.HW);
image.Save(路径, System.Drawing.Imaging.ImageFormat.Jpeg);

调试易

.net缩略图的问题~~~~~~~~~~~~~~~~~求高手赐教!

解决方案 »