图像特效---Swirl滤镜

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Swirl Filter

Swirl 滤镜是实现图像围绕中心点(cenX,cenY)扭曲旋转的效果，效果图如下：

原图

效果图

代码如下：

///

/// Swirl Filter

///

/// Source image.

/// The X position of Swirl.

/// The Y position of Swirl.

/// The degree of swirl,0-360.

/// The result image.

private Bitmap SwirlFilterProcess(Bitmap srcBitmap, int cenX, int cenY, int swilDegree)

{

Bitmap a = new Bitmap(srcBitmap);

int w = a.Width;

int h = a.Height;

int radius = 0;

swilDegree = Math.Max(0, Math.Min(360, swilDegree));

double k = swilDegree / 3600.0;

Bitmap dst = new Bitmap(w, h);

System.Drawing.Imaging.BitmapData srcData = a.LockBits(new Rectangle(0, 0, w, h), System.Drawing.Imaging.ImageLockMode.ReadWrite, System.Drawing.Imaging.PixelFormat.Format32bppArgb);

System.Drawing.Imaging.BitmapData dstData = dst.LockBits(new Rectangle(0, 0, w, h), System.Drawing.Imaging.ImageLockMode.ReadWrite, System.Drawing.Imaging.PixelFormat.Format32bppArgb);

unsafe

{

byte* pIn = (byte*)srcData.Scan0.ToPointer();

byte* pOut = (byte*)dstData.Scan0.ToPointer();

byte* p = null;

int stride = srcData.Stride - w * 4;

int offsetX = 0, offsetY = 0;

int newX = 0, newY = 0;

double radian = 0;

for (int y = 0; y < h; y++)

{

for (int x = 0; x < w; x++)

{

offsetX = x - cenX;

offsetY = y - cenY;

radian = Math.Atan2(offsetY, offsetX);

radius = (int)(Math.Sqrt(offsetX * offsetX + offsetY * offsetY));

newX = (int)(radius * Math.Cos(radian + k * radius)) + cenX;

newY = (int)(radius * Math.Sin(radian + k * radius)) + cenY;

newX = Math.Min(w - 1, Math.Max(0, newX));

newY = Math.Min(h - 1, Math.Max(0, newY));

p = pIn + newY * srcData.Stride + newX * 4;

pOut[0] = (byte)p[0];

pOut[1] = (byte)p[1];

pOut[2] = (byte)p[2];

pOut[3] = (byte)255;

pOut += 4;

}

pOut += stride;

}

a.UnlockBits(srcData);

dst.UnlockBits(dstData);

}

return dst;

}

程序demo： http://www.zealfilter.com/forum.php?mod=viewthread&tid=58&extra=page%3D1

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