CODEWITHSUNDEEP
iphoneobjective-cuiimage
hanumanDev
hanumanDev

Reputation: 6614

centering a CGRect in a view

I have an image displaying in a CGRect. how do I center the rect in the view?

here's my code:

UIImage * image = [UIImage imageNamed:place.image];
CGRect rect = CGRectMake(10.0f, 90.0f, image.size.width, image.size.height);

UIImageView * imageView = [[UIImageView alloc] initWithFrame:rect];
[imageView setImage:image];

I've tried imageView.center but to no effect.

thanks in advance.

Upvotes: 24

Views: 36452

Answers (8)

Rob
Rob

Reputation: 51

CGRect CGRectIntegralCenteredInRect(CGRect innerRect, CGRect outerRect) {
    CGFloat originX = outerRect.origin.x + ((outerRect.size.width - innerRect.size.width) * 0.5f);
    CGFloat originY = outerRect.origin.y + ((outerRect.size.height - innerRect.size.height) * 0.5f);
    return CGRectIntegral(CGRectMake(originX, originY, innerRect.size.width, innerRect.size.height));
}

Upvotes: 5

Mike Demidov
Mike Demidov

Reputation: 1127

Swift 4

let center = CGPoint(x: bounds.midX, y: bounds.midY)

Upvotes: 0

Bill Chan
Bill Chan

Reputation: 3473

For Swift 4:

CGPoint center = CGPoint(x: buttonRect.midX, y: buttonRect.midY)

Upvotes: 1

Kitt Hirasaki
Kitt Hirasaki

Reputation: 561

Looking at:

https://developer.apple.com/documentation/coregraphics/cggeometry

You can do:

CGPoint center = CGPointMake(CGRectGetMidX(mainRect), CGRectGetMidY(mainRect));

Upvotes: 56

J1soon
J1soon

Reputation: 357

If the function is called frequently, you can also use macros as shown here for simplicity.

#define Center(x) CGPointMake(CGRectGetMidX(x), CGRectGetMidY(x));

Then use it like

CGPoint myPoint = Center(myRect);

Upvotes: 0

Ben Zotto
Ben Zotto

Reputation: 71058

UIView's center is a property, not a method.

You need to calculate the actual location you want to put it in. You can do this by setting the frame of the view, or by setting its center, which is simpler in your case.

You don't say what view you then go make imageView a subview of. If you're putting it inside something called superview, you could do this:

CGPoint superCenter = CGPointMake(CGRectGetMidX([superview bounds]), CGRectGetMidY([superview bounds]));
[imageView setCenter:superCenter];

Upvotes: 27

Peter
Peter

Reputation: 1031

Position the imageView in the parentView based on the size and origin of the parentView's rect.

Given a parent view named parentView:

float parentRect = parentView.frame;
float imageRect = imageView.frame;

imageRect.origin.x = (int)(parentView.origin.x + (parentRect.size.width - imageRect.size.width) / 2);
imageRect.origin.y = (int)(parentView.origin.y + (parentRect.size.height- imageRect.size.height) / 2);
imageView.frame = imageRect;

Casting the origins to int ensures that your centered image is not blurry (though it may be off center by a subpixel amount).

Upvotes: 7

Dexter
Dexter

Reputation: 5736

CGRect r = thingToCenter.frame;
r.origin = parentView.bounds.origin;
r.origin.x = parentView.bounds.size.width / 2  - r.size.width / 2;
r.origin.y = parentView.bounds.size.height / 2  - r.size.height / 2 + 12;
thingToCenter.frame = r;

Upvotes: 6

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