CODEWITHSUNDEEP
iosiphonecore-graphicscgrectcgpoint
christo16
christo16

Reputation: 4843

Turn two CGPoints into a CGRect

How can I, given two different CGPoints, turn them into an CGRect?

Example:

CGPoint p1 = CGPointMake(0,10);
CGPoint p2 = CGPointMake(10,0);

How can I turn this into a CGRect?

Upvotes: 23

Views: 9127

Answers (7)

noppe
noppe

Reputation: 85

let r0 = CGRect(origin: p0, size: .zero)
let r1 = CGRect(origin: p1, size: .zero)
let rect = r0.union(r1).standardized

Upvotes: 1

kelin
kelin

Reputation: 11974

Swift extension:

extension CGRect {
    init(p1: CGPoint, p2: CGPoint) {
        self.init(x: min(p1.x, p2.x),
                  y: min(p1.y, p2.y),
                  width: abs(p1.x - p2.x),
                  height: abs(p1.y - p2.y))
    }
}

Upvotes: 6

colinta
colinta

Reputation: 3659

A slight modification of Ken's answer. Let CGGeometry "standardize" the rect for you.

CGRect rect = CGRectStandardize(CGRectMake(p1.x, p1.y, p2.x - p1.x, p2.y - p1.y));

Upvotes: 10

Ben Zotto
Ben Zotto

Reputation: 71008

This will take two arbitrary points and give you the CGRect that has them as opposite corners. 

CGRect r = CGRectMake(MIN(p1.x, p2.x), 
                      MIN(p1.y, p2.y), 
                      fabs(p1.x - p2.x), 
                      fabs(p1.y - p2.y));

The smaller x value paired with the smaller y value will always be the origin of the rect (first two arguments). The absolute value of the difference between x values will be the width, and between y values the height.

Upvotes: 52

hfossli
hfossli

Reputation: 22962

This function takes any number of CGPoints and gives you the smallest CGRect back.

CGRect CGRectSmallestWithCGPoints(CGPoint pointsArray[], int numberOfPoints)
{
    CGFloat greatestXValue = pointsArray[0].x;
    CGFloat greatestYValue = pointsArray[0].y;
    CGFloat smallestXValue = pointsArray[0].x;
    CGFloat smallestYValue = pointsArray[0].y;

    for(int i = 1; i < numberOfPoints; i++)
    {
        CGPoint point = pointsArray[i];
        greatestXValue = MAX(greatestXValue, point.x);
        greatestYValue = MAX(greatestYValue, point.y);
        smallestXValue = MIN(smallestXValue, point.x);
        smallestYValue = MIN(smallestYValue, point.y);
    }

    CGRect rect;
    rect.origin = CGPointMake(smallestXValue, smallestYValue);
    rect.size.width = greatestXValue - smallestXValue;
    rect.size.height = greatestYValue - smallestYValue;

    return rect;
}

Upvotes: 4

Jesse Black
Jesse Black

Reputation: 7976

This will return a rect of width or height 0 if the two points are on a line

float x,y,h,w;
if (p1.x > p2.x) {
    x = p2.x;
    w = p1.x-p2.x;
} else {
    x = p1.x;
    w = p2.x-p1.x;
}
if (p1.y > p2.y) {
    y = p2.y;
    h = p1.y-p2.y;
} else {
    y = p1.y;
    h = p2.y-p1.y;
}

CGRect newRect = CGRectMake(x,y,w,h);

Upvotes: 1

Ken Aspeslagh
Ken Aspeslagh

Reputation: 11594

Assuming p1 is the origin and the other point is the opposite corner of a rectangle, you could do this:

CGRect rect = CGRectMake(p1.x, p1.y,  fabs(p2.x-p1.x), fabs(p2.y-p1.y));

Upvotes: 4

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