图像旋转原理和旋转公式

如果果一个点（x1,y1）旋转到（x2,y2），对应的角度旋转从θ1到θ1+θ2

sinθ1=y1/sqrt(x1*x1+   y1*y1)   
cosθ1=x1/sqrt(x1*x1+   y1*y1)  

sin(θ1+θ2)=sin(θ1)*cos(θ2)+cos(θ1)*sin(θ2)=y2/sqrt(x2*x2+y2*y2)

cos(θ1+θ2)=cos(θ1)*cos(θ2)-sin(θ1)*sin(θ2)=x2/sqrt(x2*x2+y2*y2)

根据上述推到出

y2=x1*sin(θ2)+y1*cos(θ2); 

x2=x1*cos(θ2)-y1*sin(θ2);

代码举例

x1=(int)x;x2=x1+1;

 y1=int(y);y2=y1+1;

dx=float(x-x1);dx1=1.0-dx;

dy=float(y-y1);dy1=1.0-dy;

 m_tResPixelArray[i][j].rgbBlue=m_tOriPixelArray[y1][x1].rgbBlue*dx1*dy1+

 m_tOriPixelArray[y1+1][x1].rgbBlue*dx*dy1+

m_tOriPixelArray[y1][x1+1].rgbBlue*dx1*dy+

m_tOriPixelArray[y1+1][x1+1].rgbBlue*dx*dy+0.5;