Graphics 确定直线是否与CGRect相交

确定直线是否与矩形相交的最有效方法是什么

我正在寻找类似的东西：

CGPoint startLine = CGPointMake(5.0f,5.0f);
CGPoint endLine = CGPointMake(25.0f,25.0f);

CGRect intersectingRect = CGRectMake(10.0f,10.0f,50.0f,50.0f);

if (CGRectContainsLine(intersectingRect,startLine,endLine)) { //true
    //line intersects rectangle
}

---

没有内置的东西，但这应该可以做到：

BOOL RectContainsLine(CGRect r, CGPoint lineStart, CGPoint lineEnd)
{
    BOOL (^LineIntersectsLine)(CGPoint, CGPoint, CGPoint, CGPoint) = ^BOOL(CGPoint line1Start, CGPoint line1End, CGPoint line2Start, CGPoint line2End)
    {
        CGFloat q =
            //Distance between the lines' starting rows times line2's horizontal length
            (line1Start.y - line2Start.y) * (line2End.x - line2Start.x)
            //Distance between the lines' starting columns times line2's vertical length
            - (line1Start.x - line2Start.x) * (line2End.y - line2Start.y);
        CGFloat d =
            //Line 1's horizontal length times line 2's vertical length
            (line1End.x - line1Start.x) * (line2End.y - line2Start.y)
            //Line 1's vertical length times line 2's horizontal length
            - (line1End.y - line1Start.y) * (line2End.x - line2Start.x);

        if( d == 0 )
            return NO;

        CGFloat r = q / d;

        q =
            //Distance between the lines' starting rows times line 1's horizontal length
            (line1Start.y - line2Start.y) * (line1End.x - line1Start.x)
            //Distance between the lines' starting columns times line 1's vertical length
            - (line1Start.x - line2Start.x) * (line1End.y - line1Start.y);

        CGFloat s = q / d;
        if( r < 0 || r > 1 || s < 0 || s > 1 )
            return NO;

        return YES;
    };

    /*Test whether the line intersects any of:
     *- the bottom edge of the rectangle
     *- the right edge of the rectangle
     *- the top edge of the rectangle
     *- the left edge of the rectangle
     *- the interior of the rectangle (both points inside)
     */

    return (LineIntersectsLine(lineStart, lineEnd, CGPointMake(r.origin.x, r.origin.y), CGPointMake(r.origin.x + r.size.width, r.origin.y)) ||
            LineIntersectsLine(lineStart, lineEnd, CGPointMake(r.origin.x + r.size.width, r.origin.y), CGPointMake(r.origin.x + r.size.width, r.origin.y + r.size.height)) ||
            LineIntersectsLine(lineStart, lineEnd, CGPointMake(r.origin.x + r.size.width, r.origin.y + r.size.height), CGPointMake(r.origin.x, r.origin.y + r.size.height)) ||
            LineIntersectsLine(lineStart, lineEnd, CGPointMake(r.origin.x, r.origin.y + r.size.height), CGPointMake(r.origin.x, r.origin.y)) ||
            (CGRectContainsPoint(r, lineStart) && CGRectContainsPoint(r, lineEnd)));
}

BOOL RectContainsLine（CGRect r、CGPoint lineStart、CGPoint lineEnd）
{
BOOL（^LineIntersectsLine）（CGPoint，CGPoint，CGPoint，CGPoint）=^BOOL（CGPoint line1Start，CGPoint line1End，CGPoint line2Start，CGPoint line2End）
{
CGQ=
//行的起始行之间的距离乘以line2的水平长度
（line1Start.y-line2Start.y）*（line2End.x-line2Start.x）
//行的起始列之间的距离乘以line2的垂直长度
-（line1Start.x-line2Start.x）*（line2End.y-line2Start.y）；
CGD=
//第1行的水平长度乘以第2行的垂直长度
（line1End.x-line1Start.x）*（line2End.y-line2Start.y）
//第1行的垂直长度乘以第2行的水平长度
-（line1End.y-line1Start.y）*（line2End.x-line2Start.x）；
如果（d==0）
返回否；
cgr=q/d；
q=
//行的起始行之间的距离乘以行1的水平长度
（line1Start.y-line2Start.y）*（line1End.x-line1Start.x）
//行的起始列之间的距离乘以行1的垂直长度
-（line1Start.x-line2Start.x）*（line1End.y-line1Start.y）；
cgs=q/d；
如果（r<0 | | r>1 | | s<0 | | s>1）
返回否；
返回YES；
};
/*测试该线是否与以下任一点相交：
*-矩形的底边
*-矩形的右边缘
*-矩形的上边缘
*-矩形的左边缘
*-矩形的内部（两个点都在内部）
*/
返回（LineIntersectsLine（lineStart、lineEnd、CGPointMake（r.origin.x、r.origin.y）、CGPointMake（r.origin.x+r.size.width、r.origin.y））||
LineIntersectsLine（线起点、线终点、CGPointMake（r.origin.x+r.size.width、r.origin.y）、CGPointMake（r.origin.x+r.size.width、r.origin.y+r.size.height））||
LineIntersectsLine（线起点、线终点、CGPointMake（r.origin.x+r.size.width、r.origin.y+r.size.height）、CGPointMake（r.origin.x、r.origin.y+r.size.height））||
直线相交直线（直线起点、直线终点、CGPointMake（r.origin.x、r.origin.y+r.size.height）、CGPointMake（r.origin.x、r.origin.y））||
（CGRectContainsPoint（r，lineStart）和&CGRectContainsPoint（r，lineEnd））；
}

---

从这个问题中简单地引出：

对于任何使用objective-c的人：

- (BOOL)rectContainsLine:(CGRect)rect startPoint:(CGPoint)lineStart endPoint:(CGPoint)lineEnd {
BOOL (^LineIntersectsLine)(CGPoint, CGPoint, CGPoint, CGPoint) = ^BOOL(CGPoint line1Start, CGPoint line1End, CGPoint line2Start, CGPoint line2End) {

    CGFloat q =
    //Distance between the lines' starting rows times line2's horizontal length
    (line1Start.y - line2Start.y) * (line2End.x - line2Start.x)
    //Distance between the lines' starting columns times line2's vertical length
    - (line1Start.x - line2Start.x) * (line2End.y - line2Start.y);
    CGFloat d =
    //Line 1's horizontal length times line 2's vertical length
    (line1End.x - line1Start.x) * (line2End.y - line2Start.y)
    //Line 1's vertical length times line 2's horizontal length
    - (line1End.y - line1Start.y) * (line2End.x - line2Start.x);

    if( d == 0 )
        return NO;

    CGFloat r = q / d;

    q =
    //Distance between the lines' starting rows times line 1's horizontal length
    (line1Start.y - line2Start.y) * (line1End.x - line1Start.x)
    //Distance between the lines' starting columns times line 1's vertical length
    - (line1Start.x - line2Start.x) * (line1End.y - line1Start.y);

    CGFloat s = q / d;
    if( r < 0 || r > 1 || s < 0 || s > 1 )
        return NO;

    return YES;
};

/*Test whether the line intersects any of:
 *- the bottom edge of the rectangle
 *- the right edge of the rectangle
 *- the top edge of the rectangle
 *- the left edge of the rectangle
 *- the interior of the rectangle (both points inside)
 */

return (LineIntersectsLine(lineStart, lineEnd, CGPointMake(rect.origin.x, rect.origin.y), CGPointMake(rect.origin.x + rect.size.width, rect.origin.y)) ||
        LineIntersectsLine(lineStart, lineEnd, CGPointMake(rect.origin.x + rect.size.width, rect.origin.y), CGPointMake(rect.origin.x + rect.size.width, rect.origin.y + rect.size.height)) ||
        LineIntersectsLine(lineStart, lineEnd, CGPointMake(rect.origin.x + rect.size.width, rect.origin.y + rect.size.height), CGPointMake(rect.origin.x, rect.origin.y + rect.size.height)) ||
        LineIntersectsLine(lineStart, lineEnd, CGPointMake(rect.origin.x, rect.origin.y + rect.size.height), CGPointMake(rect.origin.x, rect.origin.y)) ||
        (CGRectContainsPoint(rect, lineStart) && CGRectContainsPoint(rect, lineEnd)));
}

-（BOOL）rectContainsLine:（CGRect）rect startPoint:（CGPoint）lineStart endPoint:（CGPoint）lineEnd{
BOOL（^LineIntersectsLine）（CGPoint，CGPoint，CGPoint，CGPoint）=^BOOL（CGPoint line1Start，CGPoint line1End，CGPoint line2Start，CGPoint line2End）{
CGQ=
//行的起始行之间的距离乘以line2的水平长度
（line1Start.y-line2Start.y）*（line2End.x-line2Start.x）
//行的起始列之间的距离乘以line2的垂直长度
-（line1Start.x-line2Start.x）*（line2End.y-line2Start.y）；
CGD=
//第1行的水平长度乘以第2行的垂直长度
（line1End.x-line1Start.x）*（line2End.y-line2Start.y）
//第1行的垂直长度乘以第2行的水平长度
-（line1End.y-line1Start.y）*（line2End.x-line2Start.x）；
如果（d==0）
返回否；
cgr=q/d；
q=
//行的起始行之间的距离乘以行1的水平长度
（line1Start.y-line2Start.y）*（line1End.x-line1Start.x）
//行的起始列之间的距离乘以行1的垂直长度
-（line1Start.x-line2Start.x）*（line1End.y-line1Start.y）；
cgs=q/d；
如果（r<0 | | r>1 | | s<0 | | s>1）
返回否；
返回YES；
};
/*测试该线是否与以下任一点相交：
*-矩形的底边
*-矩形的右边缘
*-矩形的上边缘
*-矩形的左边缘
*-矩形的内部（两个点都在内部）
*/
返回（LineIntersectsLine（lineStart、lineEnd、CGPointMake（rect.origin.x、rect.origin.y）、CGPointMake（rect.origin.x+rect.size.width、rect.origin.y））||
LineIntersectsLine（lineStart、lineEnd、CGPointMake（rect.origin.x+rect.size.width、rect.origin.y）、CGPointMake（rect.origin.x+rect.size.width、rect.origin.y+rect.size.height））||
LineIntersectsLine（lineStart、lineEnd、CGPointMake（rect.origin.x+rect.size.width、rect.origin.y+rect.size.height）、CGPointMake（rect.origin.x、rect.origin.y+rect.size.height））||
LineIntersectsLine（lineStart、lineEnd、CGPointMake（rect.origin.x、rect.origin.y+rect.size.height）、CGPointMake（rect.origin.x、rect.origin.y））||
（CGRectContainsPoint（rect，lineStart）和&CGRectContainsPoint（rect，lineEnd））；
}

Swift版本：

extension CGRect {
    private func lineIntersectsLine(_ line1Start: CGPoint, _ line1End: CGPoint, _ line2Start: CGPoint, _ line2End: CGPoint) -> Bool {
        // Distance between the lines' starting rows times line2's horizontal length
        var q = (line1Start.y - line2Start.y) * (line2End.x - line2Start.x)
            //Distance between the lines' starting columns times line2's vertical length
            - (line1Start.x - line2Start.x) * (line2End.y - line2Start.y)
        let d =
        //Line 1's horizontal length times line 2's vertical length
        (line1End.x - line1Start.x) * (line2End.y - line2Start.y)
        //Line 1's vertical length times line 2's horizontal length
        - (line1End.y - line1Start.y) * (line2End.x - line2Start.x)

        if d == 0 {
            return false
        }

        let r = q / d

        q =
            //Distance between the lines' starting rows times line 1's horizontal length
            (line1Start.y - line2Start.y) * (line1End.x - line1Start.x)
            //Distance between the lines' starting columns times line 1's vertical length
            - (line1Start.x - line2Start.x) * (line1End.y - line1Start.y);

        let s = q / d
        if r < 0 || r > 1 || s < 0 || s > 1 {
            return false
        }

        return true
    }


    func instersectsLine(start lineStart: CGPoint, end lineEnd: CGPoint) -> Bool
    {
        /*Test whether the line intersects any of:
         *- the bottom edge of the rectangle
         *- the right edge of the rectangle
         *- the top edge of the rectangle
         *- the left edge of the rectangle
         *- the interior of the rectangle (both points inside)
         */
        return (lineIntersectsLine(lineStart, lineEnd, CGPoint(x:self.origin.x, y: self.origin.y), CGPoint(x: self.origin.x + self.size.width, y: self.origin.y)) ||
            lineIntersectsLine(lineStart, lineEnd, CGPoint(x: self.origin.x + self.size.width, y: self.origin.y), CGPoint(x: self.origin.x + self.size.width, y: self.origin.y + self.size.height)) ||
            lineIntersectsLine(lineStart, lineEnd, CGPoint(x: self.origin.x + self.size.width, y: self.origin.y + self.size.height), CGPoint(x: self.origin.x, y: self.origin.y + self.size.height)) ||
            lineIntersectsLine(lineStart, lineEnd, CGPoint(x: self.origin.x, y: self.origin.y + self.size.height), CGPoint(x: self.origin.x, y: self.origin.y)) ||
            (contains(lineStart) && contains(lineEnd)))
    }
}

扩展CGRect{ 专用函数直线相交直线（uLine1开始：CGPoint，Line1结束：CGPoint，Line2开始：CGPoint，Line2结束：CGPoint）->Bool{ //行的起始行之间的距离乘以line2的水平长度 变量q=（line1Start.y-line2Start.y）*（line2End.x-line2Start.x） //行的起始列之间的距离乘以line2的垂直长度 -（line1Start.x-line2Start.x）*（line2End.y-line2Start.y） 让d= //第1行的水平长度乘以第2行的垂直长度 （line1End.x-line1Start.x）*（line2End.y-line2Start.y） //第1行的垂直长度乘以第2行的水平长度 -（line1End.y-line1Start.y）*（line2End.x-line2Start.x） 如果d==0{ 返回错误 } 设r=q/d q= //行的起始行之间的距离乘以l