Im wondering if there is anyway that you can get the absolute location of a control in a ipad/iphone application. e.g. I have a TextField which is within a child of a child of a view. I want to know the X and Y values in relation to the top Parent View (e.g. currently the x and Y of the textfield return 10 and 10 because that is it's frame location within its own view, but I want to know this in relation to its parent which should be something like X = 10 and Y = 220). I need to make a generic method for this somehow. Hope this make sense.
Any ideas?
You are looking for -[UIView convertPoint:toView:].
For example, to get the origin of a view view in terms of its window's base coordinates, you would write:
CGPoint localPoint = [view bounds].origin;
CGPoint basePoint = [view convertPoint:localPoint toView:nil];
If you instead want to convert the point into the coordinate system of some other view within the same window, you can use that view as the toView: argument instead of nil:
NSAssert([view window] == [otherView window],
#"%s: Views must be part of the same window.", __func__);
CGPoint otherPoint = [view convertPoint:localPoint toView:otherView];
Because different coordinate systems can have different scales, you might find -convertRect:toView: to be more useful, depending on what you're planning to do with the coordinates. There are also analogous -fromView: versions of both the point and rect conversion methods.
Related
I have the following set-up:
Where the light blue view, let's call it parentView, has a rectangular subview (the purple view) called childView. The user can use pan touches to rotate and stretch childView by putting their finger on the point exhibited by the red dot and pushing it or pulling it.
It's possible that the childView could be scaled small enough to that after the user is finished with its touches, the point denoted by the red dot would be inside of the parentView.
My goal is to create a method that can detect if the red point is in the parentView or not. I've written the following code:
CGPoint childViewRedPoint = CGPointMake(self.bounds.size.width, self.bounds.size.height / 2);
CGPoint rotatedChildViewRedPoint = CGPointApplyAffineTransform(childViewRedPoint, CGAffineTransformMakeRotation(self.rotateAngle));
CGPoint convertedChildViewRedPoint = [self convertPoint:rotatedChildViewRedPoint toView:self.superview];
if (CGRectContainsPoint(self.superview.bounds, convertedChildViewRedPoint))
{
return YES;
}
else
{
return NO;
}
First I find the red point as defined within the childView, then I rotate it by the amount that the view has been rotated, then I convert it to be in the parentViews coordinates.
The points I'm getting don't seem to make sense and this isn't working. Was wondering if anyone knows where I'm going wrong here? Am I not taking parentViews superview into account?
I am not 100% sure, but I think that convertPoint: already takes a rotation (or any other transformation) into account, so you only need:
CGPoint childViewRedPoint = CGPointMake(self.bounds.size.width, self.bounds.size.height / 2);
CGPoint convertedChildViewRedPoint = [self convertPoint:childViewRedPoint toView:self.superview];
if (CGRectContainsPoint(self.superview.bounds, convertedChildViewRedPoint))
...
My question is simple.
Let us say I use this method
CGAffineTransformMakeTranslation(5.0f, 0.0f);
which translates the image view 5 pixels to the right. But is there a similar method that does the exact same thing except takes the destination point as an argument rather then the values you want to move the image view by?
For example, if I wanted to move an image view to 100.0f, 0.0f what would I use?
You can use the following two options:
imgOne.center = CGPointMake(50, 50);
or
imgOne.frame = CGRectMake(50, 50, imgOne.frame.size.width, imgOne.frame.size.height);
If it's the center point you want to move to this coordinate, use:
imageView.center = CGPointMake(100.0f, 0.0f);
If it's one of the corner points, subtract/add half the view's frame's width/height to the coordinates. If you need this frequently, it's a good idea to write a small UIView category that allows you to position a view's corner on a particular coordinate.
I have 4 views and i am drawing circles inside these views.The user is able to move these views.How can i get the position of each view relative to the window(i mean relative to 320*480)?
I want to draw and fill a polygon using the position of views.
You can use the frame property of the UIView to retrieve its location and size. See the class reference for more information:
http://developer.apple.com/library/ios/#documentation/UIKit/Reference/UIView_Class/UIView/UIView.html
Example:
... = myView.frame.origin.x; //x-coord
... = myView.frame.origin.y; //y-coord
... = myView.frame.size.width; //width
... = myView.frame.size.height; //height
You can grab the position in the following way:
CGPoint positionOfAView = view.frame.origin;
or if transforms were applied:
CGPoint positionOFAView = view.bounds.origin;
Alternatively, you may want to grab the center:
CGPoint centerOfAView = view.center;
See this answer, too.
You have posted the same question again.(your first question) Before anybody answer's this question the same way it was answered earlier. Can you please tell,
Are you drawing the Circles in the view using CoreGraphics?
When you say 4 different views, how they are managed? Are they displayed at the same time?
Are there 4 View objects added on 1 ViewController?
You can get the position using
CGRect frame = [myView frame];
But remember it will send coordinates and origin based on its parent view
And after making changes
myView.frame = frame;
Hope this helps....
If you want to just move a view (without changing it size), consider using the center property, it might be more convenient.
Here's an example, assuming your circle structure is built in a certain way :)
myView.center = CGPointMake(circle.x + circle.width/2, circle.y + circle.height/2);
If I start with a UIImageView, and I add a subview, how do I translate a coordinate in the original UIImageView to a corresponding coordinate (the same place on the screen) in the subview?
UIView provides methods for exactly this purpose. In your case you have two options:
CGPoint newLocation = [imageView convertPoint:thePoint toView:subview];
or
CGPoint newLocation = [subview convertPoint:thePoint fromView:imageView];
They both do the same thing, so pick whichever one feels more appropriate. There's also equivalent functions for converting rects. These functions will convert between any two views on the same window. If the destination view is nil, it converts to/from the window base coordinates. These functions can handle views that aren't direct descendants of each other, and it can also handle views with transforms (though the rect methods may not produce accurate results in the case of a transform that contains any rotation or skewing).
Subtract the subview's frame.origin from the point in the parents view to the same point in the subview's coordinate:
subviewX = parentX - subview.frame.origin.x;
subviewY = parentY - subview.frame.origin.y;
Starting with code like:
UIImageView* superView=....;
UIImageView subView=[
[UIImageView alloc]initWithFrame:CGRectMake(0,0,subViewWidth,subViewHeight)
];
subView.center=CGPointMake(subViewCenterX, subViewCenterY);
[superView addSubview:subView];
The (subViewCenterX, subViewCenterY) coordinate is a point, in superView, where the center of subView is "pinned". The subView can be moved around wrt the superView by moving its center around. We can go, for example
subView.center=CGPointMake(subViewCenterX+1, subViewCenterY);
to move it 1 point to the right. Now lets say we have a point (X,Y) in the superView, and we want to find the corresponding point (x,y) in the subView, so that (X,Y) and (x,y) refer to the same point on the screen. The formula for x is:
x=X+subViewWidth/2-subViewCenterX;
and similarly for y:
y=Y+subViewHeight/2-subViewCenterY;
To explain this, if you draw a box representing the superView, and another (larger) box representing the subView, the difference subViewWidth/2-subViewCenterX is "the width of the bit of the subView box sticking out to the left of the superView"
I'd like to move a view from a scrollview to a uiview.
I'm having trouble changing it's center(or frame) so that it remains in the same position in screen (but in a different view, possibly the superview of scrollview).
How should I convert the view's center/frame?
Thank you.
EDIT:
CGPoint oldCenter = dragView.center;
CGPoint newCenter = [dragView convertPoint: oldCenter toView: self.navigationView.contentView];
dragView.center = newCenter;
[self.navigationView.contentView addSubview: dragView];
I can also use (NSSet*) touches since i'm in touchesBegan:
I was having hard time to make it work but the doc wasn't so clear to me.
You can use convertPoint:toView: method of UIView. It is used to convert a point from one view's coordinate system to another. See Converting Between View Coordinate Systems section of UIView class reference. There are more methods available.
-edit-
You are using the wrong point when calling convertPoint: method. The given point should be in dragView's coordinate system where as dragView.center is in its superview's coordinate system.
Use the following point and it should give you the center of dragView in its own coordinate system.
CGPoint p;
p = CGPointMake(dragView.bounds.size.width * 0.5, dragView.bounds.size.height * 0.5);