iOS full view background image, maintain aspect ratio, control clipping direction - ios

I'm trying to place a background image on a view, using a UIImageView or anything else that will work. I want it to fill the entire view, but maintain the aspect ratio, and allow me to control which side(s) get clipped. I'd like to use Auto Layout if possible (not code).
By setting Auto Layout constraints to keep the UIImageView the full size of the container, and setting Scale Mode to Aspect Fill, I am very close. The only problem is the image is always centered in the view, in that it is cropped on top and bottom in landscape layout and both sides in portrait. I want to be able to control that. I want to be able to "crop just the right side" (keep left edge docked to left of container), or "crop just the top". I have different images and I'll want each one to crop a different way, and possibly I'll allow users to use their own images and select from a few cropping options.
In this image, I currently get the top result, but want the option to get the bottom. The red box shows the visible area in portrait view (roughly):
My question is similar to this one: iOS Aspect Fill Image Resizing with Content Aligned to Left/Top Edge
However, I do not feel it is a duplicate because my needs are different, and I'm also including an image to help explain better. Also, I will not accept an answer of "use different images for portrait vs landscape" because that doesn't really solve the problem. If you understand my question, you would see that you would actually need a different image for every different aspect ratio, pre-cropped in each alignment I want to support. Obviously that's not really a robust solution.

Related

Need help in position images when view going back into place using

Hey everyone I've been stuck on this issue for the past few days. It's pretty hard to describe so I uploaded a video for it on a GitHub repository:
https://github.com/DJSimonSays93/PresentationController
It involves custom view controller transitions using present and the delegates UIViewControllerTransitioningDelegate and UIViewControllerAnimatedTransitioning
The "problem" is straightforward, now let me see if I can describe it in words.
You've got two image views showing, say, the basil image: the one in the scroll view, and the full-screen one when you present. They are both set at Aspect Fill. But the aspect ratio itself is different for these two image views. Therefore, in order to be displayed in Aspect Fill in a different image view, the image shifts in the way it is shown.
The reason you find this upsetting at the end of the dismiss is that you don't notice it happening at the start of the present, but if you slow down your video (you can turn on Slow Animations on the simulator, it will help), you can see it there too:
When you tap an image in the scroll view, there is a jump as the image changes its display for the new image view, and then the image view grows to its true size as the transform is removed (animated).
When you tap the full screen image, the transform is applied (animated) and then there is a jump as the image view is taken away to reveal the old image view that was behind it.
If you make both image view Scale To Fill, that won't happen. Of course then there is a distortion of the image, but it is the same distortion so that the image appears to grow and shrink smoothly right the way through. Try it and you will at least be satisfied by the sense of what I'm saying.
(See https://www.apeth.com/stretch.gif.)
If you don't want to do that, then you will have a lot more work to do; you will need to figure out how to actually compensate for the difference in aspect ratio by changing the aspect ratio of the image to match. Or, you could make the goal size of the fullscreen image view match the aspect ratio of the small image view (and part of it will just end up offscreen).
The point is, you cannot display the same image using Aspect Fill in image view with different aspect ratios and expect the image to appear the same way in both. Either the image needs to be different (to compensate) or the aspect ratios need to be the same.

XCode12: How to set up constraints in an image to make it responsive to an screen?

I'm having issues with constraints in XCode 12: Even if I describe accurately all measures involved, there is no way apparently to resize a 850x600 image to make it fit proportionally in the screen of an apple device. As you can see in the image, the constraints are defined to make the original image fit WITH BORDERS on the Iphone's screen, but nevertheless is turns out to be a disaster afterwards...
As you can see in the screen capture, the image overflows the screen when the model device is changed. So...we have a problem. And the answer or clue that I'm seeking night and day is...
How to make this image to become RESPONSIVE to screen size, and keep it's proportions. No way how the hell something so basic is so difficult in XCode...
must edit... look how the alignment constrainst are shown in grey...no idea why...this avoids me to try the solution provided by the good fellow above...
It seems you've defined constraints to center the imageView and having it a size of 850x600 pixels. This will keep the image of that exact same size, regardless the device it is shown on.
If you want the image to shrink, keeping the aspect ration you need to define constraint for the top, bottom, leading and trailing edge.
And you need to set the imageView's contentMode to "Aspect Fit", which is the default, afaik.
This is an image shown on an iPhone 11:
And this the same image shown on an iPhone 4s:
Edit:
One way to add those constraints is to select (highlight) the imageView and click on the button with the little square in the middle surrounded by those "T"s. :-)

How to properly constrain images in interface builder

I'm new to iOS development and am struggling with interface builder to layout a view that has 3 images. I want three images going across the view. So the images will need to be scaled a little differently for different devices. I am hoping to do this with constraints. I am fairly close. Here is a screenshot:
The images are actually resizing and becoming bigger on the larger device screens which is what I want and the spacing is working to stop them from overlapping each other on small devices. I just need to stop the two side images from being stretched tall. I don't want to specify a height constraint because they do need to resize for specific devices sizes. Any help to add a constraint that will make the outer images not stretch tall is much appreciated.
Set the UIImageView 's content mode to be aspect fit. It will be always stretched in it's correct aspect ratio
Instead of Scale to Fill select Aspect Fit

How would I align an image to the bottom right of the view using Size Classes in Xcode?

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).

iOS Aspect Fill Image Resizing with Content Aligned to Left/Top Edge

I am developing a universal app for iOS-7. this particular question is specific to iPad only. I want to place an image as background of root view of a View Controller i.e. the image should fill the whole screen. The 1x image has size:768x1024. This works for Portrait orientations as non-retina resolution of iPad is also 768x1024 in portrait. In Landscape however the image does not fit. I have tried using ScaleToFit but since aspect ratio of image is not preserved I can not use ScaleToFit(their are things in image which look odd when not scaled proportionally in both axis). AspectFill resizing seems most suitable for my need, but their is a small problem. As defined in Apple Documentation "The content is resized to completely fill the bounds rectangle, while still preserving the aspect of the content. The content is centered in the axis it exceeds.". I do not want the content to be centered in axis in which it exceeds, I want it to be aligned to top/left edge.
So basically I want two things:
Aspect Fill
The content remains aligned on the Left/Top edge.
Is it possible to achieve this. Any code-snippet will be great.
Thanks
You will have to subclass the View Controller's view and manually scale and align.
Look at the code snippets in THIS answer.
Adjust imageViewXOrigin and imageViewYOrigin to align however you want.
Really the only way to get around the content fill mode is to have two different images, one for each orientation. I'd suggest changing the image in the view controllers willAnimateToOrientation: method so that you can put the image changes inside UIKit's animation block.

Resources