指向圈内

Question

给定圆的中心点和半径，我如何知道某个点（x，y）是否在圆中？谁知道呢？感谢。

Answer 1

最初你问过Objective-C。

CGFloat DistanceBetweenTwoPoints(CGPoint point1,CGPoint point2)
{
    CGFloat dx = point2.x - point1.x;
    CGFloat dy = point2.y - point1.y;
    return sqrt(dx*dx + dy*dy );
};

-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
    CGPoint point = [[touches anyObject] locationInView:self];
    CGFloat distance = DistanceBetweenTwoPoints(self.circleCenter, point);
    if(distance < self.radius){
        //inside the circle
    }
}

此代码假定您处理子类视图中的圆圈。