以任意比例缩放图片例子

【核心代码】

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();
		}
		
	}
}