按照指定大小,生成缩略图

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/*
 说明:按照指定大小,生成缩略图
 作者:Blue.Dream
*/
using System;
using System.Drawing;
using System.Drawing.Imaging;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
using System.IO;

namespace test
{
 /// <summary>
 /// Form1 的摘要说明。
 /// </summary>
 public class Form1 : System.Windows.Forms.Form
 {
  //声明加密字符生成的随机数的位数
  public const int LENGTH = 32;
  //声明加密字符前后的分隔长度
  public const int LEN = 4;
  private System.Windows.Forms.GroupBox groupBox1;
  private System.Windows.Forms.GroupBox groupBox2;
  private System.Windows.Forms.Button btn_Browser;
  private System.Windows.Forms.Button button2;
  private System.Windows.Forms.PictureBox imgSource;
  private System.Windows.Forms.PictureBox imgObject;
  private string SourceFile;  
  private System.Windows.Forms.Label label1;
  private System.Windows.Forms.ComboBox local;
  /// <summary>
  /// 必需的设计器变量。
  /// </summary>
  private System.ComponentModel.Container components = null;

  public Form1()
  {
   //
   // Windows 窗体设计器支持所必需的
   //
   InitializeComponent();
   this.Init();

   //
   // TODO: 在 InitializeComponent 调用后添加任何构造函数代码
   //
  }

  private void Init()
  {
   DataTable ht = new DataTable();
   DataColumn objcol = new DataColumn("Keys");
   objcol.DataType = typeof(System.String);
   ht.Columns.Add(objcol);
   objcol = new DataColumn("Value");
   objcol.DataType = typeof(System.Int32);
   ht.Columns.Add(objcol);
   DataRow row = ht.NewRow();
   row[0] = "800*600";
   row[1] = 1;
   ht.Rows.Add(row);
   row = ht.NewRow();
   row[0] = "640*480";
   row[1] = 2;
   ht.Rows.Add(row);
   row = ht.NewRow();
   row[0] = "420*360";
   row[1] = 3;
   ht.Rows.Add(row);
   row = ht.NewRow();
   row[0] = "340*270";
   row[1] = 4;
   ht.Rows.Add(row);
   row = ht.NewRow();
   row[0] = "240*180";
   row[1] = 5;
   ht.Rows.Add(row);
   row = ht.NewRow();
   row[0] = "120*90";
   row[1] = 6;
   ht.Rows.Add(row);


   this.local.DataSource = ht;
   this.local.DisplayMember = "Keys";
   this.local.ValueMember = "Value";
  }
  
  /// <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 Form Designer generated code
  /// <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.groupBox1 = new System.Windows.Forms.GroupBox();
   this.imgSource = new System.Windows.Forms.PictureBox();
   this.groupBox2 = new System.Windows.Forms.GroupBox();
   this.imgObject = new System.Windows.Forms.PictureBox();
   this.btn_Browser = new System.Windows.Forms.Button();
   this.button2 = new System.Windows.Forms.Button();
   this.local = new System.Windows.Forms.ComboBox();
   this.label1 = new System.Windows.Forms.Label();
   this.groupBox1.SuspendLayout();
   this.groupBox2.SuspendLayout();
   this.SuspendLayout();
   //
   // groupBox1
   //
   this.groupBox1.Controls.AddRange(new System.Windows.Forms.Control[] {
                     this.imgSource});
   this.groupBox1.Name = "groupBox1";
   this.groupBox1.Size = new System.Drawing.Size(288, 296);
   this.groupBox1.TabIndex = 0;
   this.groupBox1.TabStop = false;
   this.groupBox1.Text = "源图";
   //
   // imgSource
   //
   this.imgSource.Location = new System.Drawing.Point(8, 16);
   this.imgSource.Name = "imgSource";
   this.imgSource.Size = new System.Drawing.Size(272, 272);
   this.imgSource.TabIndex = 0;
   this.imgSource.TabStop = false;
   //
   // groupBox2
   //
   this.groupBox2.Controls.AddRange(new System.Windows.Forms.Control[] {
                     this.imgObject});
   this.groupBox2.Location = new System.Drawing.Point(304, 0);
   this.groupBox2.Name = "groupBox2";
   this.groupBox2.Size = new System.Drawing.Size(352, 296);
   this.groupBox2.TabIndex = 0;
   this.groupBox2.TabStop = false;
   this.groupBox2.Text = "结果图";
   //
   // imgObject
   //
   this.imgObject.Location = new System.Drawing.Point(8, 16);
   this.imgObject.Name = "imgObject";
   this.imgObject.Size = new System.Drawing.Size(336, 272);
   this.imgObject.TabIndex = 0;
   this.imgObject.TabStop = false;
   //
   // btn_Browser
   //
   this.btn_Browser.Location = new System.Drawing.Point(24, 312);
   this.btn_Browser.Name = "btn_Browser";
   this.btn_Browser.TabIndex = 1;
   this.btn_Browser.Text = "源 图";
   this.btn_Browser.Click += new System.EventHandler(this.btn_Browser_Click);
   //
   // button2
   //
   this.button2.Location = new System.Drawing.Point(552, 312);
   this.button2.Name = "button2";
   this.button2.TabIndex = 2;
   this.button2.Text = "生 成";
   this.button2.Click += new System.EventHandler(this.button2_Click);
   //
   // local
   //
   this.local.Location = new System.Drawing.Point(256, 312);
   this.local.Name = "local";
   this.local.Size = new System.Drawing.Size(112, 20);
   this.local.TabIndex = 4;
   this.local.Text = "--请选择--";
   //
   // label1
   //
   this.label1.Location = new System.Drawing.Point(216, 312);
   this.label1.Name = "label1";
   this.label1.Size = new System.Drawing.Size(32, 23);
   this.label1.TabIndex = 6;
   this.label1.Text = "大小";
   this.label1.TextAlign = System.Drawing.ContentAlignment.MiddleRight;
   //
   // Form1
   //
   this.AutoScaleBaseSize = new System.Drawing.Size(6, 14);
   this.ClientSize = new System.Drawing.Size(664, 365);
   this.Controls.AddRange(new System.Windows.Forms.Control[] {
                    this.label1,
                    this.local,
                    this.button2,
                    this.btn_Browser,
                    this.groupBox1,
                    this.groupBox2});
   this.Name = "Form1";
   this.Text = "Form1";
   this.groupBox1.ResumeLayout(false);
   this.groupBox2.ResumeLayout(false);
   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 btn_Browser_Click(object sender, System.EventArgs e)
  {
   using(OpenFileDialog dlg = new OpenFileDialog())
   {
    if(dlg.ShowDialog() == DialogResult.OK)
    {
     string file = dlg.FileName;
     if(File.Exists(file))
     {      
      this.SourceFile = file;
      imgSource.Image = new Bitmap(file);
     }
    }
    dlg.Dispose();
   }
  }

  private void button2_Click(object sender, System.EventArgs e)
  {
   int select = (int)this.local.SelectedValue;
   Point p = new Point(340,270);
   switch(select)
   {
    case 1:
     p.X = 800;
     p.Y = 600;
     break;
    case 2:
     p.X = 640;
     p.Y = 480;
     break;
    case 3:
     p.X = 480;
     p.Y = 360;
     break;
    case 4:
     p.Y = 340;
     p.X = 270;
     break;
    case 5:
     p.X = 240;
     p.Y = 180;
     break;
    case 6:
     p.X = 120;
     p.Y = 90;
     break;    
   }

   //生成目标文件地址   
   FileInfo objFile = new FileInfo(this.SourceFile);
   string filepath = objFile.DirectoryName;
   string filename = objFile.Name;
   string saveFile = filepath + "
\\Thumb"+filename;
   if(MakeThumbnailImage(this.SourceFile,saveFile,p.X,p.Y,objFile.Extension.ToLower()))
    this.imgObject.Image = new Bitmap(saveFile);
   else
    MessageBox.Show("FAILD");

  }

  /// <summary>
  /// 按照指定大小,生成缩略图
  /// </summary>
  /// <param name="sourceFile">源文件</param>
  /// <param name="saveFile">存储文件</param>
  /// <param name="width">缩略图的宽度</param>
  /// <param name="height">缩略图的高度</param>
  /// <param name="strType">文件类型</param>
  /// <returns></returns>
  private bool MakeThumbnailImage(string sourceFile,string saveFile,int width,int height,string strType)
  {
   if( !File.Exists(sourceFile) )  //判断文件是否存在
    return false;
   bool result = true;
   Bitmap sourceImage = new Bitmap(sourceFile);
   System.Drawing.Image.GetThumbnailImageAbort myCallBack = new Image.GetThumbnailImageAbort(ThumbnailCallBack);
   Image objImage = sourceImage.GetThumbnailImage(width,height,myCallBack,IntPtr.Zero); //取得缩略图
   
   try
   { 
    objImage.Save(saveFile,GetImageType(strType));
   }
   catch
   {
    result = false;
   }
   finally
   {
    objImage.Dispose();
    sourceImage.Dispose();
   }
   return result;
   
  }

  private System.Drawing.Imaging.ImageFormat GetImageType(string strType)
  {
   switch(strType)
   {
    case ".jpg":
     return ImageFormat.Jpeg;
    case ".jpeg":
     return ImageFormat.Jpeg;
    case ".gif":
     return ImageFormat.Gif;
    case ".bmp":
     return ImageFormat.Bmp;
    case ".tiff":
     return ImageFormat.Tiff;
    case ".ico":
     return ImageFormat.Icon;
    case ".png":
     return ImageFormat.Png;
    case ".emf":
     return ImageFormat.Emf;
    default:
     return ImageFormat.Jpeg;
   }
  }

  private bool ThumbnailCallBack()
  {
   return false;
  }
  
 }
}

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