cocos2d-x 获取图片的某像素点的RGBA颜色

转自：http://www.cnblogs.com/jaoye/archive/2013/02/19/2916501.html

ccColor4B c = {, , , };
CCPoint pt = ccp(,);//要获取的点
unsigned int x = pt.x, y = pt.y;

CCImage * myimg = new CCImage();
//加载 图片
myimg->initWithImageFileThreadSafe("HelloWorld1.png");
unsigned char *data_=myimg->getData();
unsigned int *pixel = (unsigned int *)data_;
pixel = pixel + (y * ) + x;        //480 是图片的宽
c.r = *pixel & 0xff;
c.g = (*pixel >> ) & 0xff;
c.b = (*pixel >> ) & 0xff;
c.a = (*pixel >> ) & 0xff;          //这个值  就是透明度