.NET CF C# 位圖的任意角度旋轉

 因為在.NET Framework下的許多API在.NET CF上不能使用，客觀上增加了圖檔任意角度旋轉的難度，在經過幾天的研究之後，并且結合網上的資料，算法如下，僅供參考，由該代碼引起的任何問題本人不負任何責任，并遵照開源代碼傳播協定。

private Bitmap GetNewBmp(ref Bitmap oldbmp, int angle)

{

angle = angle % 360;

//if (angle > 180) angle = 360 - angle;

//if (angle < -180) angle = 360 + angle;

float radians = (float)(2 * Math.PI * angle) / 360;

float cos = (float)Math.Cos(radians);

float sin = (float)Math.Sin(radians);

float Point1x = -oldbmp.Height * sin;

float Point1y = oldbmp.Height * cos;

float Point2x = oldbmp.Width * cos - oldbmp.Height * sin;

float Point2y = oldbmp.Height * cos + oldbmp.Width * sin;

float Point3x = oldbmp.Width * cos;

float Point3y = oldbmp.Width * sin;

float minx = Math.Min((float)0, Math.Min(Point1x, Math.Min(Point2x, Point3x)));

float miny = Math.Min((float)0, Math.Min(Point1y, Math.Min(Point2y, Point3y)));

float maxx = Math.Max(Point1x, Math.Max(Point2x, Point3x));

float maxy = Math.Max(Point1y, Math.Max(Point2y, Point3y));

int DestBmpWidth, DestBmpHeight;

if (angle > 90 && angle < 180)

DestBmpWidth = (int)Math.Ceiling(-minx);

else

DestBmpWidth = (int)Math.Ceiling(maxx - minx);

if (angle > 180 && angle < 270)

DestBmpHeight = (int)Math.Ceiling(-miny);

else

DestBmpHeight = (int)Math.Ceiling(maxy - miny);

Bitmap newbmp = new Bitmap(DestBmpWidth, DestBmpHeight);

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

{

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

{

int srcbmpX = (int)((x + minx) * cos + (y + miny) * sin);

int srcbmpY = (int)((y + miny) * cos - (x + minx) * sin);

if (srcbmpX >= 0 && srcbmpX < oldbmp.Width

&& srcbmpY >= 0 && srcbmpY < oldbmp.Height)

newbmp.SetPixel(x, y, oldbmp.GetPixel(srcbmpX, srcbmpY));

}

}

return newbmp;

}

轉自：http://www.devdiv.net/bbs/viewthread.php?tid=11713