Hoffe das hilft
Daniel
...
ThumbMaker thumbMaker = new ThumbMaker(@"c:\Image.gif");
thumbMaker.ResizeToPng(100, 0, @"c:\ScaledImage.png");
...
public class ThumbMaker
{
Double xFactor;
Double yFactor;
System.IntPtr sourceScan0;
int sourceStride;
Bitmap scaledBitmap, bitmap;
public ThumbMaker(string fileName)
{
bitmap = new Bitmap(fileName);
}
public ThumbMaker(Stream stream)
{
bitmap = new Bitmap(stream);
}
void AdjustSizes(ref int xSize, ref int ySize)
{
if (xSize != 0 && ySize == 0)
ySize = Math.Abs((int) (xSize *
bitmap.Height / bitmap.Width));
else if (xSize == 0 && ySize != 0)
xSize = Math.Abs((int) (ySize *
bitmap.Width / bitmap.Height));
else if (xSize == 0 && ySize == 0)
{
xSize = bitmap.Width;
ySize = bitmap.Height;
}
}
//Internal resize for indexed colored images
void IndexedRezise(int xSize, int ySize)
{
BitmapData sourceData;
BitmapData targetData;
AdjustSizes(ref xSize, ref ySize);
scaledBitmap = new Bitmap(xSize, ySize,
bitmap.PixelFormat);
scaledBitmap.Palette = bitmap.Palette;
sourceData = bitmap.LockBits(new Rectangle(0, 0,
bitmap.Width, bitmap.Height),
ImageLockMode.ReadOnly,
bitmap.PixelFormat);
try
{
targetData = scaledBitmap.LockBits(new
Rectangle(0, 0, xSize, ySize),
ImageLockMode.WriteOnly,
scaledBitmap.PixelFormat);
try
{
xFactor = (Double) bitmap.Width
/ (Double) scaledBitmap.Width;
yFactor = (Double) bitmap.Height
/ (Double) scaledBitmap.Height;
sourceStride =
sourceData.Stride;
sourceScan0 = sourceData.Scan0;
int targetStride =
targetData.Stride;
System.IntPtr targetScan0 =
targetData.Scan0;
unsafe
{
byte * p = (byte *)(void
*)targetScan0;
int nOffset =
targetStride - scaledBitmap.Width;
int nWidth =
scaledBitmap.Width;
for(int y=0;y <
scaledBitmap.Height;++y)
{
for(int x=0; x <
nWidth; ++x )
{
p[0] =
GetSourceByteAt(x, y);
++p;
}
p += nOffset;
}
}
}
finally
{
scaledBitmap.UnlockBits(targetData);
}
}
finally
{
bitmap.UnlockBits(sourceData);
}
}
//This gets the color index on the source image for
coords x, y on the resized target image
byte GetSourceByteAt(int x, int y)
{
unsafe
{
return ((byte*) ((int)sourceScan0 +
(int) (Math.Floor(y * yFactor) * sourceStride) +
(int) Math.Floor(x *
xFactor)))[0];
}
}
//Internal resize for RGB colored images
void RGBRezise(int xSize, int ySize)
{
AdjustSizes(ref xSize, ref ySize);
scaledBitmap = new Bitmap(xSize, ySize,
PixelFormat.Format24bppRgb);
Graphics g = Graphics.FromImage(scaledBitmap);
Rectangle destRect = new Rectangle(0, 0, xSize,
ySize);
g.InterpolationMode =
InterpolationMode.HighQualityBicubic;
g.SmoothingMode = SmoothingMode.AntiAlias;
g.DrawImage(bitmap, destRect);
}
void Save(string fileName, ImageFormat format)
{
scaledBitmap.Save(fileName, format);
}
void Save(string fileName, long jQuality, ImageFormat
format)
{
ImageCodecInfo jpegCodecInfo =
GetEncoderInfo("image/jpeg");
Encoder qualityEncoder = Encoder.Quality;
EncoderParameters encoderParams = new
EncoderParameters(1);
EncoderParameter qualityEncoderParam = new
EncoderParameter(qualityEncoder, jQuality);
encoderParams.Param[0] = qualityEncoderParam;
scaledBitmap.Save(fileName, jpegCodecInfo,
encoderParams);
}
void Save(Stream stream, ImageFormat format)
{
scaledBitmap.Save(stream, format);
}
void Save(Stream stream, long jQuality, ImageFormat
format)
{
ImageCodecInfo jpegCodecInfo =
GetEncoderInfo("image/jpeg");
Encoder qualityEncoder = Encoder.Quality;
EncoderParameters encoderParams = new
EncoderParameters(1);
EncoderParameter qualityEncoderParam = new
EncoderParameter(qualityEncoder, jQuality);
encoderParams.Param[0] = qualityEncoderParam;
scaledBitmap.Save(stream, jpegCodecInfo,
encoderParams);
}
ImageCodecInfo GetEncoderInfo(String mimeType)
{
int j;
ImageCodecInfo[] encoders;
encoders = ImageCodecInfo.GetImageEncoders();
for(j = 0; j < encoders.Length; ++j)
{
if(encoders[j].MimeType.ToUpper() ==
mimeType.ToUpper())
return encoders[j];
}
return null;
}
public void ResizeToJpeg(int xSize, int ySize, string
fileName)
{
this.RGBRezise(xSize, ySize);
this.Save(fileName, ImageFormat.Jpeg);
}
public void ResizeToJpeg(int xSize, int ySize, Stream
stream)
{
this.RGBRezise(xSize, ySize);
this.Save(stream, ImageFormat.Jpeg);
}
public void ResizeToJpeg(int xSize, int ySize, long
jQuality, string fileName)
{
this.RGBRezise(xSize, ySize);
this.Save(fileName, jQuality, ImageFormat.Jpeg);
}
public void ResizeToJpeg(int xSize, int ySize, long
jQuality, Stream stream)
{
this.RGBRezise(xSize, ySize);
this.Save(stream, jQuality, ImageFormat.Jpeg);
}
public void ResizeToGif(int xSize, int ySize, string
fileName)
{
this.IndexedRezise(xSize, ySize);
this.Save(fileName, ImageFormat.Gif);
}
public void ResizeToGif(int xSize, int ySize, Stream
stream)
{
this.IndexedRezise(xSize, ySize);
this.Save(stream, ImageFormat.Gif);
}
public void ResizeToPng(int xSize, int ySize, string
fileName)
{
this.IndexedRezise(xSize, ySize);
this.Save(fileName, ImageFormat.Png);
}
public void ResizeToPng(int xSize, int ySize, Stream
stream)
{
this.IndexedRezise(xSize, ySize);
this.Save(stream, ImageFormat.Png);
}
}
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