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))
...
Related
Is there a way to know if a 'tap' is inside or outside the masked area of a UIView? I'm using CoreGraphics to mask the UIView.
So far my code goes something like this..
- (void)viewDidLoad {
UIGestureRecogniser *r = [[UIGestureRecogniser alloc] initWithTarget:self action:#selector(gestCall:)];
[self addGestureRecogniser:r];
}
- (void)gestCall:(UIGestureRecogniser *)gestRec {
if ("somthing") {
// outside of mask
} else {
// inside of mask
}
}
Thank you.
I've finally found the solution I was looking for. So for the benefit of any one trying to find is a CGPoint is inside any CGPath.
It's simple.
UIBezierPath *p = [UIBezierPath bezierPathWithCGPath:anyCGPath];
BOOL isInPath = [p containsPoint:anyCGPoint];
Basically you need to check the touch coordinate and decide whether is falls into the mask area or not. Override the hitTest:withEvent: and account for the image mask. You can use [[[self layer] presentationLayer] hitTest:aPoint] or [[[self layer] mask] hitTest:aPoint] in your overridden `-[UIView hitTest:withEvent:].
[EDIT]
Check if a user tapped near a CGPath might help to find answer to your question.
[EDIT]
Do following in your Gesture Handler to figure out to process tap or not.
Specify the center of the circle (This would be UIView.Center as CGPoint)
Specify the radius of pie chart
When user tap on the view, get the location as point - CGPoint and calculate point.x*point.x+point.y*point.y (Circle formulae) and this value must be less than or equal to the square of the radius i.e radius*radius. If this condition satisfied then your tap point is inside the circle otherwise outside.
Hope that makes clear.
I have a color map within a UIScrollView and am trying to sample the color of a pixel of this map. The sample reticle is positioned above the scrollview, while the user moves the contents of the scrollview under the reticle.
The user can drop the reticle with a tap gesture, but I would like to offer an extra option of moving the view under the reticle.
I'm trying to find out how I can understand what x,y coordinate of the zoomed view is currently under the reticle. The logic for this so far eludes me, especially since zooming in/out is involved.
-(void)scrollViewDidScroll:(UIScrollView *)scrollView
{
CGPoint mapLocation = [tapGestureRecognizer locationInView:self.surfaceMap];
NSLog(#"mapLocation (x,y) %.0f,%.0f",mapLocation.x,mapLocation.y);
NSLog(#"contentOffset (x,y) %.0f,%.0f",self.scrollView.contentOffset.x,self.scrollView.contentOffset.y);
//calculate where the marker is pointing to in the surface map while the scrollview is scrolling
int frameWidth = self.surfaceMap.frame.size.width;
int frameHeight = self.surfaceMap.frame.size.height;
//this is what I'm trying to calculate
CGPoint trueLocation = CGPointMake(self.scrollView.contentOffset.x+frameWidth-self.surfaceMap.frame.origin.x, self.scrollView.contentOffset.y-self.surfaceMap.frame.origin.y);
NSLog(#"trueLocation (x,y) %.0f,%.0f",trueLocation.x,trueLocation.y);
[self colorOfPixelAtPoint:trueLocation];
}
Any input is appreciated!
You may want to a have look at these two methods in UIView:
- (CGPoint)convertPoint:(CGPoint)point toView:(UIView *)view;
- (CGPoint)convertPoint:(CGPoint)point fromView:(UIView *)view;
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);
My goal is simple; I want to create a program that displays an UIImage, and when swiped from bottom to top, displays another UIImage. The images here could be a happy face/sad face. The sad face should be the starting point, the happy face the end point. When swiping your finger the part below the finger should be showing the happy face.
So far I tried solving this with the frame and bounds properties of the UIImageview I used for the happy face image.
What this piece of code does is wrong, because the transition starts in the center of the screen and not the bottom. Notice that the origin of both frame and bounds are at 0,0...
I have read numerous pages about frames and bounds, but I don't get it. Any help is appreciated!
The loadimages is called only once.
- (void)loadImages {
sadface = [UIImage imageNamed:#"face-sad.jpg"];
happyface = [UIImage imageNamed:#"face-happy.jpg"];
UIImageView *face1view = [[UIImageView alloc]init];
face1view.image = sadface;
[self.view addSubview:face1view];
CGRect frame;
CGRect contentRect = self.view.frame;
frame = CGRectMake(0, 0, contentRect.size.width, contentRect.size.height);
face1view.frame = frame;
face2view = [[UIImageView alloc]init];
face2view.layer.masksToBounds = YES;
face2view.contentMode = UIViewContentModeScaleAspectFill;
face2view.image = happyface;
[self.view addSubview:face2view];
frame = CGRectMake(startpoint.x, 0, contentRect.size.width, contentRect.size.height);
face2view.frame = frame;
face2view.clipsToBounds = YES;
}
-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
CGPoint movepoint = [[touches anyObject] locationInView: self.view];
NSLog(#"movepoint: %f %f", movepoint.x, movepoint.y);
face2view.bounds = CGRectMake(0, 0, 320, 480 - movepoint.y);
}
The UIImages and UIImageViews are properly disposed of in the dealloc function.
Indeed, you seem to be confused about frames and bounds. In fact, they are easy. Always remember that any view has its own coordinate system. The frame, center and transform properties are expressed in superview's coordinates, while the bounds is expressed in the view's own coordinate system. If a view doesn't have a superview (not installed into a view hierarchy yet), it still has a frame. In iOS the frame property is calculated from the view's bounds, center and transform. You may ask what the hell frame and center mean when there's no superview. They are used when you add the view to another view, allowing to position the view before it's actually visible.
The most common example when a view's bounds differ from its frame is when it is not in the upper left corner of its superview: its bounds.origin may be CGPointZero, while its frame.origin is not. Another classic example is UIScrollView, which frequently modifies its bounds.origin to make subviews scroll (in fact, modifying the origin of the coordinate system automatically moves every subview without affecting their frames), while its own frame is constant.
Back to your code. First of all, when you already have images to display in image views, it makes sense to init the views with their images:
UIImageView *face1view = [[UIImageView alloc] initWithImage: sadface];
That helps the image view to immediately size itself properly. It is not recommended to init views with -init because that might skip some important code in their designated initializer, -initWithFrame:.
Since you add face1view to self.view, you should really use its bounds rather than its frame:
face1view.frame = self.view.bounds;
Same goes for the happier face. Then in -touchesMoved:… you should either change face2view's frame to move it inside self.view or (if self.view does not contain any other subviews besides faces) modify self.view's bounds to move both faces inside it together. Instead, you do something weird like vertically stretching the happy face inside face2view. If you want the happy face to slide from the bottom of self.view, you should initially set its frame like this (not visible initially):
face2view.frame = CGRectOffset(face2view.frame, 0, CGRectGetHeight(self.view.bounds));
If you choose to swap faces by changing image views' frames (contrasted with changing self.view's bounds), I guess you might want to change both the views' frame origins, so that the sad face slides up out and the happy face slides up in. Alternatively, if you want the happy face to cover the sad one:
face2view.frame = face1view.frame;
Your problem seems to have something to do with the face2view.bounds in touchesMoved.
You are setting the bounds of this view to the rect, x:0, y:0, width:320, height:480 - y
x = 0 == left on the x axis
y = 0 == top on the y axis
So you are putting this image frame at the upper left corner, and making it fill the whole view. That's not what you want. The image simply becomes centered in this imageView.