核心代码是这个///<author>Arild Fines</author> ///<date>20.04.2002</date> using System; using System.Drawing; using System.Drawing.Drawing2D; using System.Drawing.Imaging; using System.Runtime.InteropServices;namespace BitmapToRegion { /// <summary> /// determines the meaning of the transparencyKey argument to the Convert method /// </summary> public enum TransparencyMode { /// <summary> /// the color key is used to define the transparent region of the bitmap /// </summary> ColorKeyTransparent, /// <summary> /// the color key is used to define the area that should _not_ be transparent /// </summary> ColorKeyOpaque } /// <summary> /// a class to convert a color-keyed bitmap into a region /// </summary> public class BitmapToRegion { /// <summary> /// ctor made private to avoid instantiation /// </summary> private BitmapToRegion() {} /// <summary> /// the meat of this class /// converts the bitmap to a region by scanning each line one by one /// this method will not affect the original bitmap in any way /// </summary> /// <param name="bitmap">The bitmap to convert</param> /// <param name="transparencyKey">The color which will indicate either transparency or opacity</param> /// <param name="mode">Whether the transparency key should indicate the transparent or the opaque region</param> public unsafe static Region Convert( Bitmap bitmap, Color transparencyKey, TransparencyMode mode ) { //sanity check if ( bitmap == null ) throw new ArgumentNullException( "Bitmap", "Bitmap cannot be null!" ); //flag = true means the color key represents the opaque color bool modeFlag = ( mode == TransparencyMode.ColorKeyOpaque );
GraphicsUnit unit = GraphicsUnit.Pixel; RectangleF boundsF = bitmap.GetBounds( ref unit ); Rectangle bounds = new Rectangle( (int)boundsF.Left, (int)boundsF.Top, (int)boundsF.Width, (int)boundsF.Height ); uint key = (uint)((transparencyKey.A << 24) | (transparencyKey.R << 16) | (transparencyKey.G << 8) | (transparencyKey.B << 0)); //get access to the raw bits of the image BitmapData bitmapData = bitmap.LockBits( bounds, ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb ); uint* pixelPtr = (uint*)bitmapData.Scan0.ToPointer(); //avoid property accessors in the for int yMax = (int)boundsF.Height; int xMax = (int)boundsF.Width; //to store all the little rectangles in GraphicsPath path = new GraphicsPath(); for ( int y = 0; y < yMax; y++ ) { //store the pointer so we can offset the stride directly from it later //to get to the next line byte* basePos = (byte*)pixelPtr; for ( int x = 0; x < xMax; x++, pixelPtr++ ) { //is this transparent? if yes, just go on with the loop if ( modeFlag ^ ( *pixelPtr == key ) ) continue; //store where the scan starts int x0 = x; //not transparent - scan until we find the next transparent byte while( x < xMax && !( modeFlag ^ ( *pixelPtr == key ) ) ) { ++x; pixelPtr++; } //add the rectangle we have found to the path path.AddRectangle( new Rectangle( x0, y, x-x0, 1 ) ); } //jump to the next line pixelPtr = (uint*)(basePos + bitmapData.Stride); } //now create the region from all the rectangles Region region = new Region( path ); //clean up path.Dispose(); bitmap.UnlockBits( bitmapData ); return region; } }
///<date>20.04.2002</date>
using System;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.Runtime.InteropServices;namespace BitmapToRegion
{ /// <summary>
/// determines the meaning of the transparencyKey argument to the Convert method
/// </summary>
public enum TransparencyMode
{
/// <summary>
/// the color key is used to define the transparent region of the bitmap
/// </summary>
ColorKeyTransparent,
/// <summary>
/// the color key is used to define the area that should _not_ be transparent
/// </summary>
ColorKeyOpaque
} /// <summary>
/// a class to convert a color-keyed bitmap into a region
/// </summary>
public class BitmapToRegion
{
/// <summary>
/// ctor made private to avoid instantiation
/// </summary>
private BitmapToRegion()
{}
/// <summary>
/// the meat of this class
/// converts the bitmap to a region by scanning each line one by one
/// this method will not affect the original bitmap in any way
/// </summary>
/// <param name="bitmap">The bitmap to convert</param>
/// <param name="transparencyKey">The color which will indicate either transparency or opacity</param>
/// <param name="mode">Whether the transparency key should indicate the transparent or the opaque region</param>
public unsafe static Region Convert( Bitmap bitmap, Color transparencyKey,
TransparencyMode mode )
{
//sanity check
if ( bitmap == null )
throw new ArgumentNullException( "Bitmap", "Bitmap cannot be null!" ); //flag = true means the color key represents the opaque color
bool modeFlag = ( mode == TransparencyMode.ColorKeyOpaque );
GraphicsUnit unit = GraphicsUnit.Pixel;
RectangleF boundsF = bitmap.GetBounds( ref unit );
Rectangle bounds = new Rectangle( (int)boundsF.Left, (int)boundsF.Top,
(int)boundsF.Width, (int)boundsF.Height ); uint key = (uint)((transparencyKey.A << 24) | (transparencyKey.R << 16) |
(transparencyKey.G << 8) | (transparencyKey.B << 0));
//get access to the raw bits of the image
BitmapData bitmapData = bitmap.LockBits( bounds, ImageLockMode.ReadOnly,
PixelFormat.Format32bppArgb );
uint* pixelPtr = (uint*)bitmapData.Scan0.ToPointer(); //avoid property accessors in the for
int yMax = (int)boundsF.Height;
int xMax = (int)boundsF.Width; //to store all the little rectangles in
GraphicsPath path = new GraphicsPath(); for ( int y = 0; y < yMax; y++ )
{
//store the pointer so we can offset the stride directly from it later
//to get to the next line
byte* basePos = (byte*)pixelPtr; for ( int x = 0; x < xMax; x++, pixelPtr++ )
{
//is this transparent? if yes, just go on with the loop
if ( modeFlag ^ ( *pixelPtr == key ) )
continue; //store where the scan starts
int x0 = x; //not transparent - scan until we find the next transparent byte
while( x < xMax && !( modeFlag ^ ( *pixelPtr == key ) ) )
{
++x;
pixelPtr++;
} //add the rectangle we have found to the path
path.AddRectangle( new Rectangle( x0, y, x-x0, 1 ) );
}
//jump to the next line
pixelPtr = (uint*)(basePos + bitmapData.Stride);
} //now create the region from all the rectangles
Region region = new Region( path ); //clean up
path.Dispose();
bitmap.UnlockBits( bitmapData ); return region;
} }
}