Opencv求兩個矩形是否相交，以及相交的比值

在影像處理中經常會遇到判斷兩個矩形是否相交，以及相交的比例的情況，下面是來自TLD演算法中源碼的求法：

float bbOverlap(const BoundingBox& box1,const BoundingBox& box2){  if (box1.x > box2.x+box2.width) { return 0.0; }  if (box1.y > box2.y+box2.height) { return 0.0; }  if (box1.x+box1.width < box2.x) { return 0.0; }  if (box1.y+box1.height < box2.y) { return 0.0; }  float colInt =  min(box1.x+box1.width,box2.x+box2.width) - max(box1.x, box2.x);  float rowInt =  min(box1.y+box1.height,box2.y+box2.height) - max(box1.y,box2.y);  float intersection = colInt * rowInt;  float area1 = box1.width*box1.height;  float area2 = box2.width*box2.height;  return intersection / (area1 + area2 - intersection);}