兩個矩形之間的距離

Question

如何找到兩個矩形之間的距離？相交距離應該返回0。

Answer 1

下面是用於計算由CGSize表示的兩個CGRects之間距離的快速功能：

CGSize CGSizeDistanceBetweenRects(CGRect rect1, CGRect rect2) 
{ 
    if (CGRectIntersectsRect(rect1, rect2)) 
    { 
     return CGSizeMake(0, 0); 
    } 

    CGRect mostLeft = rect1.origin.x < rect2.origin.x ? rect1 : rect2; 
    CGRect mostRight = rect2.origin.x < rect1.origin.x ? rect1 : rect2; 

    CGFloat xDifference = mostLeft.origin.x == mostRight.origin.x ? 0 : mostRight.origin.x - (mostLeft.origin.x + mostLeft.size.width); 
    xDifference = MAX(0, xDifference); 

    CGRect upper = rect1.origin.y < rect2.origin.y ? rect1 : rect2; 
    CGRect lower = rect2.origin.y < rect1.origin.y ? rect1 : rect2; 

    CGFloat yDifference = upper.origin.y == lower.origin.y ? 0 : lower.origin.y - (upper.origin.y + upper.size.height); 
    yDifference = MAX(0, yDifference); 

    return CGSizeMake(xDifference, yDifference); 
} 

Answer 2

在一個稍微有關說明，這裏是如何計算中心兩個給定CGRects的之間的距離：

CGFloat CGRectGetDistanceBetweenCenters(CGRect rect1, CGRect rect2) 
{ 
    CGPoint center1 = CGPointMake(CGRectGetMidX(rect1), CGRectGetMidY(rect1)); 
    CGPoint center2 = CGPointMake(CGRectGetMidX(rect2), CGRectGetMidY(rect2)); 

    CGFloat horizontalDistance = (center2.x - center1.x); 
    CGFloat verticalDistance = (center2.y - center1.y); 

    CGFloat distance = sqrt((horizontalDistance * horizontalDistance) + (verticalDistance * verticalDistance)); 

    return distance; 
}