How could I use UIImageView with aspectFill and alignment to the top? Auto-layout or programmatically don't mind.
It can be done, but you are talking about quite a bit of coding. Let's start with a detailed description of what you are asking for.
We'll start with an iPhone6s in portrait mode with a screen size of 667x375 points, or a regular height by compressed width in size classes.
(Keep in mind, on any iPad you'll also need to work with slide-over and split screen too.)
But for now we'll go with 667x375. Into that we'll add our imageView as a square size of 375x375. Along the top of the screen when in portrait mode.
(Keep in mind that with AutoLayout you'll also have it pinned, and without putting some code in to determine if it's in landscape or portrait, otherwise, that 375x375 will shrink in landscape if you have other views underneath it.)
So now, stripped out to the most minimum (for now), we are talking about how to pin "an image" to the top of a UIImageView that is 375x375 in size and with a contentMode of aspectFill.
We need to find the size of the image next, based on both the largest dimension (height or width) AND how that dimension compares to the size of the imageView, calculate how the imageView will normally render it. The key figure you want is the height it will render it as
For instance, how will a 480x1020 (HxW) image fit into it? The 1020 width will be taken down to 375, so the height will be 480/(1020375) or 176.4705 points.
Always do the math for both dimensions - if your imageView isn't square or if the height isn't the "bounded" dimension, you'll be off.
Once you've calculated what the "Aspect Filled" height will be, check it against the dimensions of the imageView, and adjust the height of it as needed.
Here's where the real work comes in. If you are using AutoLayout, you can do a heightAnchor adjustment, but depending on how you pinned those other views things may be laid out really bad after you do. If you are using frames and CGRects be aware that you have to take into account iPad slide-out and split screen, etc.
Finally, if you want your app to load a different image in that imageView after it was loaded, you will have to "reset" the height back to what it originally was, at least in your calculations.
My recommendation is to find an alternative to what you are asking. For instance, put a small border around the image view to let the user know the true dimensions of that view.
Related
I have an image thats a particular height and width and its designed in such a way where its content is meant to be displayed at a minimum height, and as the height increases more of the image is allowed to be seen (meant to clip at the frame). This is because we wanted to serve up one image, but depending on device size, the frame can get display as much of the photo necessary.
My question is whats the best way to manage the content mode of the UIImageView to allow for this as well as how should the imageview constraints should be managed. Any advice? My original thought was to have the content mode be 'center' and use a combination of greater and less than height constraints to achieve the height part.
The red rect shows the uiimageview frame at its small screen size (iPhone SE), green is at normal size (iPhone) and orange is for plus devices.
Perhaps the community has a better solve for this?
I've an UIScrollView and I want to update his size according to his UIImageView background to exactly stay in the paper.
That the constraints I've added.
In othe size the result is wrong for example iphone 6s plus:
(It's fine in iPhone4s obviously)
I am assuming the picture with the rubber, marker, pencil and the stack of paper is a single UIImageView, and that the UIScrollView is on top of those.
If that is the case, you will have a very hard time to do what you are trying to, as you will have dynamically no idea how the stack of paper will be resized.
My solution would be to isolate each part of your drawing (the rubber, the marker, the pencil and the paper stack) in separate UIImageViews, then add the scrollView as a subview of the paper stack view: see this picture.
From there, add constraints to resize the scrollview dynamically according to its superview.
If you used full image, you have to use multiplier, not constant.
To do it, you need to calculate the position rate and use it for multiplier.
I've attached some images for example. It will be helpful for your project.
Only need to get the position rate and size rate of the object in origin image.
Setting multiplier for equal width with super view
Setting multiplier for Align center X with super view
Result in iPhone 4s
Result in iPhone 6
I have an image that I want to align with the bottom right corner of the View and then I want the rest of the image to scale to fill the available space but without falling off screen.
My image is a square, so I don't want the width of the image to be any greater than the device's shortest side (portrait or landscape).
I'm new to Size Classes, but no matter what constraints I apply, the image grows bigger than the view and seems to have a gap between the bottom and right had edges of the screen, even though I've set those constraints to 0.
Your specifications are a little unclear, which may account for the difficulty you're having; you need to be very clear on exactly what you want. I had no trouble making a square image be square and fill the shorter dimension exactly in both orientations:
So if that's what you want, it's easily achieved with constraints (no size classes involved).
I have simply dragged UIImageView into storyboard and made it square. I added a pink background to show the effects of the leftover space in the ImageView. In each case I added either a taller image (1st image) and a wider image (2nd image), as well as a text label. Here are my results.
So the obvious question is....how can I get rid of this extra (pink) space and keep the integrity of the photo (that is, to not have to stretch or lose part of the image)? If I wanted to be able to scroll through photos, it would be nice to have them all the same width to the edge so they look neat and orderly (if they were portrait), and if I wanted to have text under each, I'd want the text to be closer to it, rather than have all the blank (pink) space in between if it were landscape. And obviously different size images will give different sizes of blank space.
So I'm thinking what I could do is before displaying the image, get the size of it, then just have a designated distance from either the label or the edge of screen, depending on the orientation of the picture, and then creating/changing the size of the UIImageView with a bit of math and using the image dimensions before inserting the picture into the ImageView. Is this possible? Is there another method I can't quite figure out?
Just look at any decent photo app and they are nice and neatly organized/displayed despite being different sizes, orientations, etc and I'm wondering how to pull this off. I obviously haven't gotten too deep into using images past simply showing them in a pre-determined ImageView.
Thanks for the help/suggestions!
Try this... set your UIImageView to AspectFit (not AspectFill since that will lose some of the image) and using constraints do the following:
centre the UIImageView in the container both horizontally and vertically
set the UILabel to float below the UIImageView by whatever distance you desire ("standard" is usually good)
set the left, right, and top constraints on the UIImageView to be >= whatever distance you desire
set the bottom constraint on the UILabel to be (once again) >= whatever distance you desire
The effect of this should be that the UIImageView will properly resize itself to its intrinsic size and the constraints should properly position it and the label.
Please see screen shot of flower setup below. The flower image has been correctly loaded from an asset catalog and when the app is run on various simulators the correct pixel resolution is assigned to each device. My problem is how to get the flower image to be scaled (equally sized to fit) the same on each device ??
I have learnt how to position the image to different positions using constraints and frames but the image never scales correctly - please see first pic
The following image is a mock up of what I want to be able to do (flower image scaled correctly on each device)
Judging by your mockups, it looks like you want the image to fill half the width, and keep its square aspect ratio to determine its height. One way to approach this would be to use AutoLayout to make a left UIImageView and a right placeholder (blank) view. Pin the left view to the left edge of the parent, the right view to the right edge, and then set them to be 0 pixels from each other. Then set an equal widths constraint on them. Finally, control drag the image view to itself and you can select aspect ratio -- and assuming that in IB, the width and height is the same, it will keep it square. Adding an equal heights constraint will give the other view the height it needs to be equal in case you need that.
This gives you a left image view that is 50% and with your mode set to Aspect Fit or Aspect Fill, it should give you the results in your mockups. In case you have an image that isn't square, make sure to check Clip Subviews for your UIImageView to prevent showing the overflow.
The real problem is that your goals are not well defined. Scaled with respect to what? The screen has a height and a width. You can't scale with respect to both, because that would distort the image (because different devices have different overall aspect ratios). Thus you have to pick one dimension that you will scale to.
Judging from your mockup, I'm going to guess that what you want is to scale with respect to height. If so, then give the image view a height constraint that is a fixed fraction of its superview's height. It looks to be about 0.25 in your mockups but you will have to eyeball what you think is a good fraction.
Now, if the content mode of the image view is Aspect Fit (or Aspect Fill), the image will change its height along with the image view without distorting the aspect ratio.
However, it would be best if you would make the other dimension (here, the width) of the image view a fixed fraction of the height, such as to make the aspect ratio of the image view the same as the aspect ratio of the image. The reason is that otherwise the image might end up centered in the image view in such a way that it doesn't touch the top or left any more, even though the image view itself does.
CGFloat screen_width = [[UIScreen mainScreen] bounds].size.width;
your_imageview.frame = CGRectMake(0, 0, screen_width/2, screen_width/2);