I am building a custom UIView that you can rotate and resize. I can resize the UIView by dragging the corners of the UIView. I calculate how much I have dragged then change the frame of the UIView accordingly.
However, I am running into problems once I added a rotation gesture recognizer to the view. If I rotate or apply a transform to the view, I no longer know how to calculate drag distance and change the frame of the view. How could I calculate the width and height change between my new view and the original view when things are put at an added angle or if they have some other transform, like a translation transform?
I thought of possibilities to set the view's transform back to .identity, change the size of the view, then re-apply its transform, but I'm not sure how to actually go about implementing this.
After applying transform you can not use frame
You have two options
1) First Calculate everything using center of your view
2) As you know apply identity and change frame
for point 2 I have added example that might helpful to you
let transform = imageView.transform
imageView.transform = CGAffineTransform.identity
var rect: CGRect = imageView.frame
rect = // Change Rect here
imageView.frame = rect // Assign it
imageView.transform = transform // Apply Transform
I have a UIView and I've added a UIView inside it as a subview. I'm hoping to expand the subview to fill a portion of the view, as a percentage, for example:
subview.bounds.width = view.bound.width(num1/max)
where num1 changes every second until it reaches max.
A UIView's frame can't be partially changed - to get the result you're looking for, you need to create a new frame, manipulate it, then attach it to your subview, like so:
let newFrame = subview.frame
newFrame.size.width = view.frame.width * num1 / max
subview.frame = newFrame
I need to resize an UImageView dynamically
for that I need to find the UImageview's absolute rect on screen, x,y is what i need actually.
because my ImageView is inside another view, if i query the ImageView frame, i get x,y of it to be 0,0
how do I find the absolute rect on screen ?
try using
CGRect targetFrame = [self.view convertRect:imageView.frame fromView:imageView];
I am trying to move the UIPageControl dots so they are not centered. Is this possible? I created my own PageControl class, but the bounds are show the width at 185. I can't seem to change the width to make it as wide as the UIWindow (320)?
Any suggestions?
CGRect currentBounds = self.bounds; <--- always 185 width
You don't need to change the width. Simply move the control:
[self setFrame:CGRectMake(x, y, self.frame.size.width, self.frame.size.height]
I am creating a UIImageView and adding it in a loop to my view, I set the initial frame to 0,0,1,47 and each passage of the loop I change the center of the image view to space them out.
I am always using 0 as the origin.y
The problem is the origin reference is in the centre of the image view, assuming we was in interface builder, this is equivalent to the image below.
How can I change the reference point in code ?
After reading these answers and your comments I'm not really sure what is your point.
With UIView you can set position by 2 ways:
center – It definitely says it is the center.
frame.origin – Top left corner, can't be set directly.
If you want the bottom left corner to be at x=300, y=300 you can just do this:
UIView *view = ...
CGRect frame = view.frame;
frame.origin.x = 300 - frame.size.width;
frame.origin.y = 300 - frame.size.height;
view.frame = frame;
But if you go one level deeper to magical world of CALayers (don' forget to import QuartzCore), you are more powerful.
CALayer has these:
position – You see, it don't explicitely says 'center', so it may not be center!
anchorPoint – CGPoint with values in range 0..1 (including) that specifies point inside the view. Default is x=0.5, y=0.5 which means 'center' (and -[UIView center] assumes this value). You may set it to any other value and the position property will be applied to that point.
Example time:
You have a view with size 100x100
view.layer.anchorPoint = CGPointMake(1, 1);
view.layer.position = CGPointMake(300, 300);
Top left corner of the view is at x=200, y=200 and its bottom right corner is at x=300, y=300.
Note: When you rotate the layer/view it will be rotated around the anchorPoint, that is the center by default.
Bu since you just ask HOW to do specific thing and not WHAT you want to achieve, I can't help you any further now.
The object's frame includes its position in its superview. You can change it with something like:
CGRect frame = self.imageView.frame;
frame.origin.y = 0.0f;
self.imageView.frame = frame;
If I am understanding you correctly, you need to set the frame of the image view you are interested in moving. This can be done in the simple case like this:
_theImageView.frame = CGRectMake(x, y, width, height);
Obviously you need to set x, y, width, and height yourself. Please also be aware that a view's frame is in reference to its parent view. So, if you have a view that is in the top left corner (x = 0, y = 0), and is 320 points wide and 400 points tall, and you set the frame of the image view to be (10, 50, 100, 50) and then add it as a subview of the previous view, it will sit at x = 10, y = 50 of the parent view's coordinate space, even though the bounds of the image view are x = 0, y = 0. Bounds are in reference to the view itself, frame is in reference to the parent.
So, in your scenario, your code might look something like the following:
CGRect currentFrame = _theImageView.frame;
currentFrame.origin.x = 0;
currentFrame.origin.y = 0;
_theImageView.frame = currentFrame;
[_parentView addSubview:_theImageView];
Alternatively, you can say:
CGRect currentFrame = _theImageView.frame;
_theImageView.frame = CGRectMake(0, 0, currentFrame.size.width, currentFrame.size.height);
[_parentView addSubview:_theImageView];
Either approach will set the image view to the top left of the parent you add it to.
I thought I would take a cut at this in Swift.
If one would like to set a views position on the screen by specifying the coordinates to an origin point in X and Y for that view, with a little math, we can figure out where the center of the view needs to be in order for the origin of the frame to be located as desired.
This extension uses the frame of the view to get the width and height.
The equation to calculate the new center is almost trivial. See the below extension :
extension CGRect {
// Created 12/16/2020 by Michael Kucinski for anyone to reuse as desired
func getCenterWhichPlacesFrameOriginAtSpecified_X_and_Y_Coordinates(x_Position: CGFloat, y_Position: CGFloat) -> CGPoint
{
// self is the CGRect
let widthDividedBy2 = self.width / 2
let heightDividedBy2 = self.height / 2
// Calculate where the center needs to be to place the origin at the specified x and y position
let desiredCenter_X = x_Position + widthDividedBy2
let desiredCenter_Y = y_Position + heightDividedBy2
let calculatedCenter : CGPoint = CGPoint(x: desiredCenter_X, y: desiredCenter_Y)
return calculatedCenter // Using this point as the center will place the origin at the specified X and Y coordinates
}
}
Usage as shown below to place the origin in the upper left corner area, 25 pixels in :
// Set the origin for this object at the values specified
maskChoosingSlider.center = maskChoosingSlider.frame.getCenterWhichPlacesFrameOriginAtSpecified_X_and_Y_Coordinates(x_Position: 25, y_Position: 25)
If you want to pass a CGPoint into the extension instead of X and Y coordinates, that's an easy change you can make on your own.