C# 制作出任意不规则按钮! (原理根据背景图绘制button)

using System.Drawing.Drawing2D;
private void button3_Paint(object sender, System.Windows.Forms.PaintEventArgs e)
  { this.button3.Cursor = Cursors.Hand;
         Bitmap bmpBob =(Bitmap)this.button3.Image;     
      GraphicsPath graphicsPath = CalculateControlGraphicsPath(bmpBob);
     this.button3.Region = new Region(graphicsPath); 
  }
  private static GraphicsPath CalculateControlGraphicsPath(Bitmap bitmap)
  {
  
   GraphicsPath graphicsPath = new GraphicsPath();
 
 
   Color colorTransparent = bitmap.GetPixel(0, 0);
 
   int colOpaquePixel = 0;
 
   for(int row = 0; row < bitmap.Height; row ++)
   {
   
    colOpaquePixel = 0;
  
    for(int col = 0; col < bitmap.Width; col ++)
    {
   
     if(bitmap.GetPixel(col, row) != colorTransparent)
     {
     
      colOpaquePixel = col;
   
      int colNext = col;


http://www.51132.com/Html/c/14212553284.html

上面的代码测试效果不好，放上一个老外写的类，下过好一点：
using System;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Windows.Forms;

namespace BitmapRegionTest
{
    /// <summary>
    /// Summary description for BitmapRegion.
    /// </summary>
    public class BitmapRegion
    {
        public BitmapRegion()
        {}

        /// <summary>
        /// Create and apply the region on the supplied control
        /// </summary>
        /// The Control object to apply the region to
        /// The Bitmap object to create the region from
        public static void CreateControlRegion(Control control, Bitmap bitmap)
        {
            // Return if control and bitmap are null
            if(control == null || bitmap == null)
                return;
           
            // Set our control's size to be the same as the bitmap
            control.Width = bitmap.Width;
            control.Height = bitmap.Height;

            // Check if we are dealing with Form here
            if(control is System.Windows.Forms.Form)
            {
                // Cast to a Form object
                Form form = (Form)control;

                // Set our form's size to be a little larger that the bitmap just
                // in case the form's border style is not set to none in the first place
                form.Width += 15;
                form.Height += 35;

                // No border
                form.FormBorderStyle = FormBorderStyle.None;

                // Set bitmap as the background image
                form.BackgroundImage = bitmap;

                // Calculate the graphics path based on the bitmap supplied
                GraphicsPath graphicsPath = CalculateControlGraphicsPath(bitmap);

                // Apply new region
                form.Region = new Region(graphicsPath);
            }

            // Check if we are dealing with Button here
            else if(control is System.Windows.Forms.Button)
            {
                // Cast to a button object
                Button button = (Button)control;

                // Do not show button text
                button.Text = "";
               
                // Change cursor to hand when over button
                button.Cursor = Cursors.Hand;

                // Set background image of button
                button.BackgroundImage = bitmap;
               
                // Calculate the graphics path based on the bitmap supplied
                GraphicsPath graphicsPath = CalculateControlGraphicsPath(bitmap);

                // Apply new region
                button.Region = new Region(graphicsPath);
            }
        }

        /// <summary>
        /// Calculate the graphics path that representing the figure in the bitmap
        /// excluding the transparent color which is the top left pixel.
        /// </summary>
        /// The Bitmap object to calculate our graphics path from
        /// <returns>Calculated graphics path</returns>
        private static GraphicsPath CalculateControlGraphicsPath(Bitmap bitmap)
        {
            // Create GraphicsPath for our bitmap calculation
            GraphicsPath graphicsPath = new GraphicsPath();

            // Use the top left pixel as our transparent color
            Color colorTransparent = bitmap.GetPixel(0, 0);

            // This is to store the column value where an opaque pixel is first found.
            // This value will determine where we start scanning for trailing opaque pixels.
            int colOpaquePixel = 0;

            // Go through all rows (Y axis)
            for(int row = 0; row < bitmap.Height; row ++)
            {
                // Reset value
                colOpaquePixel = 0;

                // Go through all columns (X axis)
                for(int col = 0; col < bitmap.Width; col ++)
                {
                    // If this is an opaque pixel, mark it and search for anymore trailing behind
                    if(bitmap.GetPixel(col, row) != colorTransparent)
                    {
                        // Opaque pixel found, mark current position
                        colOpaquePixel = col;

                        // Create another variable to set the current pixel position
                        int colNext = col;

                        // Starting from current found opaque pixel, search for anymore opaque pixels
                        // trailing behind, until a transparent pixel is found or minimum width is reached
                        for(colNext = colOpaquePixel; colNext < bitmap.Width; colNext ++)
                            if(bitmap.GetPixel(colNext, row) == colorTransparent)
                                break;

                        // Form a rectangle for line of opaque pixels found and add it to our graphics path
                        graphicsPath.AddRectangle(new Rectangle(colOpaquePixel, row, colNext - colOpaquePixel, 1));

                        // No need to scan the line of opaque pixels just found
                        col = colNext;
                    }
                }
            }

            // Return calculated graphics path
            return graphicsPath;
        }
    }
}