How to get x1 &x2 origin?
self.spinner=[[UIActivityIndicatorView alloc]initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge];
float x1,x2,y1,y2;
x1=self.view.frame.origin.x;
x2=self.view.frame.origin.x;
y1=self.view.frame.origin.y;
y2=self.view.frame.origin.y;
self.spinner.center=CGPointMake((x1+x2)/2,(y1+y2)/2);
[self.spinner startAnimating];
[self.view addSubview:self.spinner];
i have a spinner,i try to place a spinner in mid point ,i know the concept but how to get that x1&x2 origin really i have confused with this...
I think you are not making point by
float x1,x2,y1,y2;
x1=self.view.frame.origin.x;
x2=self.view.frame.origin.x;
y1=self.view.frame.origin.y;
y2=self.view.frame.origin.y;
If you have to put indicator in the center of view,
self.spinner.center = self.view.center;
You have misunderstood how a rectangle is represented, your formula is based on using two corners but NSRect stores one corner, origin, and the width and height, size - see the documentation. There are also convenience macros for calculating the various properties (max coord etc.) of a rectangle - see the docs as above.
However, for this particular task you might wish to use UIView's center property, which will save you the math.
NSRect
is created with
x,y,width & height
It's also has the centre property, which is a
CGPoint
.
To work it out manually,
center.x = origin.x + size.width/2.
.. And similarly for
center.y
.
Related
I have two image views. The first is the blueish arrow, and the second is the white circle, with a black dot drawn to represent the center of the circle.
I'm trying to rotate the arrow so it's anchor point is the black dot in the picture like this
Right now I'm setting the anchor point of the arrow's layer to a point calculated like this
CGFloat y = _userImageViewContainer.center.y - CGRectGetMinY(_directionArrowView.frame);
CGFloat x = _userImageViewContainer.center.x - CGRectGetMinX(_directionArrowView.frame);
CGFloat yOff = y / CGRectGetHeight(_directionArrowView.frame);
CGFloat xOff = x / CGRectGetWidth(_directionArrowView.frame);
_directionArrowView.center = _userImageViewContainer.center;
CGPoint anchor = CGPointMake(xOff, yOff);
NSLog(#"anchor: %#", NSStringFromCGPoint(anchor));
_directionArrowView.layer.anchorPoint = anchor;
Since the anchor point is set as a percentage of the view, i.e. the coords for the center are (.5, .5), I'm calculating the percentage of the height in arrow's frame where the black dot falls. But my math, even after working out by hand, keeps resulting in .5, which isn't right because it's further than half way down when the arrow is in the original position (vertical, with the point up).
I'm rotating based on the user's compass heading
CLHeading *heading = [notif object];
// update direction of arrow
CGFloat degrees = [self p_calculateAngleBetween:[PULAccount currentUser].location.coordinate
and:_user.location.coordinate];
_directionArrowView.transform = CGAffineTransformMakeRotation((degrees - heading.trueHeading) * M_PI / 180);
The rotation is correct, it's just the anchor point that's not working right. Any ideas of how to accomplish this?
I've always found the anchor point stuff flaky, especially with rotation. I'd try something like this.
CGPoint convertedCenter = [_directionArrowView convertPoint:_userImageViewContainer.center fromView:_userImageViewContainer ];
CGSize offset = CGSizeMake(_directionArrowView.center.x - convertedCenter.x, _directionArrowView.center.y - convertedCenter.y);
// I may have that backwards, try the one below if it offsets the rotation in the wrong direction..
// CGSize offset = CGSizeMake(convertedCenter.x -_directionArrowView.center.x , convertedCenter.y - _directionArrowView.center.y);
CGFloat rotation = 0; //get your angle (radians)
CGAffineTransform tr = CGAffineTransformMakeTranslation(-offset.width, -offset.height);
tr = CGAffineTransformConcat(tr, CGAffineTransformMakeRotation(rotation) );
tr = CGAffineTransformConcat(tr, CGAffineTransformMakeTranslation(offset.width, offset.height) );
[_directionArrowView setTransform:tr];
NB. the transform property on UIView is animatable, so you could put that last line there in an animation block if desired..
Maybe better use much easier solution - make arrow image size bigger, and square. So the black point will be in center of image.
Please compare attached images and you understand what I'm talking about
New image with black dot in center
Old image with shifted dot
Now you can easy use standard anchor point (0.5, 0.5) to rotate edited image
What I want to do is to rotate and bounce my UIView simultaneously. So currently, I am using this code in my UIViewAnimation block.
[view setTransform:CGAffineTransformRotate(CGAffineTransformIdentity, -M_PI*2)];
CGPoint center = CGPointMake( view.center.x - x , view.center.y - y);
[view setCenter:center];
And using this, its rotation is happening fine but the view bouncing is not happening i.e not any kind of movement is happening at all. Guidance needed on what I am doing wrong here of if I am missing something.
Use the transform to do both things by applying a rotation and a translation (be careful of the order you apply them in). When you apply a transform to a view you shouldn't then try to change its frame (or center).
I'm using UIKit Dynamics to push a UIView off screen, similar to how Tweetbot performs it in their image overlay.
I use a UIPanGestureRecognizer, and when they end the gesture, if they exceed the velocity threshold it goes offscreen.
[self.animator removeBehavior:self.panAttachmentBehavior];
CGPoint velocity = [panGestureRecognizer velocityInView:self.view];
if (fabs(velocity.y) > 100) {
self.pushBehavior = [[UIPushBehavior alloc] initWithItems:#[self.scrollView] mode:UIPushBehaviorModeInstantaneous];
[self.pushBehavior setTargetOffsetFromCenter:centerOffset forItem:self.scrollView];
self.pushBehavior.active = YES;
self.pushBehavior.action = ^{
CGPoint lowestPoint = CGPointMake(CGRectGetMinX(self.imageView.bounds), CGRectGetMaxY(self.imageView.bounds));
CGPoint convertedPoint = [self.imageView convertPoint:lowestPoint toView:self.view];
if (!CGRectIntersectsRect(self.view.bounds, self.imageView.frame)) {
NSLog(#"outside");
}
};
CGFloat area = CGRectGetWidth(self.scrollView.bounds) * CGRectGetHeight(self.scrollView.bounds);
CGFloat UIKitNewtonScaling = 5000000.0;
CGFloat scaling = area / UIKitNewtonScaling;
CGVector pushDirection = CGVectorMake(velocity.x * scaling, velocity.y * scaling);
self.pushBehavior.pushDirection = pushDirection;
[self.animator addBehavior:self.pushBehavior];
}
I'm having an immense amount of trouble detecting when my view actually completely disappears from the screen.
My view is setup rather simply. It's a UIScrollView with a UIImageView within it. Both are just within a UIViewController. I move the UIScrollView with the pan gesture, but want to detect when the image view is off screen.
In the action block I can monitor the view as it moves, and I've tried two methods:
1. Each time the action block is called, find the lowest point in y for the image view. Convert that to the view controller's reference point, and I was just trying to see when the y value of the converted point was less than 0 (negative) for when I "threw" the view upward. (This means the lowest point in the view has crossed into negative y values for the view controller's reference point, which is above the visible area of the view controller.)
This worked okay, except the x value I gave to lowestPoint really messes everything up. If I choose the minimum X, that is the furthest to the left, it will only tell me when the bottom left corner of the UIView has gone off screen. Often times as the view can be rotating depending on where the user pushes from, the bottom right may go off screen after the left, making it detect it too early. If I choose the middle X, it will only tell me when the middle bottom has gone off, etc. I can't seem to figure out how to tell it "just get me the absolute lowest y value.
2. I tried CGRectIntersectsRect as shown in the code above, and it never says it's outside, even seconds after it went shooting outside of any visible area.
What am I doing wrong? How should I be detecting it no longer being visible?
If you take a look on UIDynamicItem protocol properties, you can see they are center, bounds and transform. So UIDynamicAnimator actually modifies only these three properties. I'm not really sure what happens with the frame during the Dynamics animations, but from my experience I can tell it's value inside the action block is not always reliable. Maybe it's because the frame is actually being calculated by CALayer based on center, transform and bounds, as described in this excellent blog post.
But you for sure can make use of center and bounds in the action block. The following code worked for me in a case similar to yours:
CGPoint parentCenter = CGPointMake(CGRectGetMidX(self.view.bounds), CGRectGetMidY(self.view.bounds));
self.pushBehavior.action = ^{
CGFloat dx = self.imageView.center.x - parentCenter.x;
CGFloat dy = self.imageView.center.y - parentCenter.y;
CGFloat distance = sqrtf(dx * dx + dy * dy);
if(distance > MIN(parentCenter.y + CGRectGetHeight(self.imageView.bounds), parentCenter.x + CGRectGetWidth(self.imageView.bounds))) {
NSLog(#"Off screen!");
}
};
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Closed 10 years ago.
Possible Duplicate:
Rotate CGPath without changing its position
I searched and tested a variety of code for a couple of hours and I can't get this to work.
I am adding an arbitrary UIBezierPath at a random location to a CAShapeLayer which gets added to a view. I need to rotate the path so that I can handle device rotations. I can rotate the layer instead of the path. I just need the result to be rotated.
I already have methods to handle transforming the bezier path by scaling and translation. It works great, but now I need to simply rotate 90 degrees left or right.
Any recommendations on how to do this?
Basic code:
UIBezierPath *path = <create arbitrary path>
CAShapeLayer *layer = [CAShapeLayer layer];
[self addPathToLayer:layer
fromPath:path];
// I could get the center of the box but where is the box center for the view it is in?
// CGRect box = CGPathGetPathBoundingBox(path.CGPath);
// layer.anchorPoint = ? How to find the center of the box for the anchor point?
// Rotating here appears to rotate around 0,0 of the view
layer.transform = CATransform3DMakeRotation(DegreesToRadians(-90), 0.0, 0.0, 1.0);
I see the following post:
BezierPath Rotation in a UIView
I suppose I could rotate as-is and then translate the path back into place. I just need to figure out what the translation values would be.
I should also state that what I am seeing after I try to rotate is that the image moves off-screen somewhere. I tried rotating 25 degrees to see movement and it pivots around the view's origin of 0,0 so that if I rotate 90 degrees the image is off-screen. I am running these test WITHOUT rotating the device - just to see how rotation works.
UPDATE #1 - 12/4/2012: For some bizarre reason if I set the position to a value I found empirically it moves the rotated bezier path into the correct position after rotation:
layer.position = CGPointMake(280, 60);
This values are a guess from starting/stopping the app and making adjustments. I have no idea why I need to adjust the position on rotation. The anchor point should be in the center of the layer. However, I did find that both the frame and position of a CAShapeLayer are all ZERO even though the path is set, and also the fact that the path is in the correct position within the view. The 280, 60 position shifts the path into what would be the center of the path bounding box when a rotation of +90 is made. If I change the rotation value I need to adjust the position. I should not have to do this manually adjustment.
I think a last resort is to somehow convert the bezier path to an image and then add it. I found that if I set the layer content to an image, then rotate, it rotates about its center point with no positional adjustment needed. Not so with setting the path.
UPDATE #2 12/4/2012 - I tried setting the frame and with fiddling I get it to center as follows:
CGRect box = CGPathGetPathBoundingBox(path.CGPath);
CGRect rect = CGRectMake(0, 0, box.origin.x + (3.5 * box.size.width), box.origin.y + (3.5 * box.size.height));
layer.frame = rect;
layer.transform = CATransform3DMakeRotation(DegreesToRadians(90), 0.0, 0.0, 1.0);
Why multiply by 3.5? I have no clue. I found that adding the box origin with about 3.5 times the size of the box shifts the rotated CAShapeLayer path to about where it should be.
There must be a better way to do this. This is a better solution than my previous post since the frame size does not depend on the rotation angle. I just don't know why the frame needs to be set to the value I am setting it to. I THOUGHT it should be
CGRectMake(0, 0, box.origin.x + (box.size.width / 2), box.origin.y + (box.size.height / 2));
However, it shifts the image to the left too much.
Another clue I found is that if I set the frame of [self view].frame (the frame of the entire parent view, which is the screen of the iPhone), then rotate, the rotation point is the center of the screen, an the path/image orbits around this center point. This is why I tried shifting the frame to what the center of the path should be so that it orbits around the box center.
UPDATE #3 12/4/2012 - I tried to render the layer as an image. However, it appears that just setting the path of a layer does not make it an "image" in the layer since it is empty
CGRect box = CGPathGetPathBoundingBox(path.CGPath);
layer.frame = box;
UIImage *image = [ImageHelper imageFromLayer:layer]; // ImageHelper library I created
CAShapeLayer *newLayer = [CAShapeLayer layer];
newLayer.frame = CGRectMake(box.origin.x, box.origin.y, image.size.width, image.size.height);
newLayer.contents = (id) image.CGImage;
It appears that rotating the layer with its path set is no different than simply rotating the bezier path itself. I will go back to rotating the bezier path and see if I can fiddle with the position elements or something. There's got to be a solution to this.
Goal: Rotate a UIBezierPath around its center point within the view it was originally created in.
UPDATE #4 12/4/2012 - I ran a series of tests measuring the values needed for translation in order to place a UIBezierPath in its previous center location.
CGAffineTransform rotate = CGAffineTransformMakeRotation(DegreesToRadians(-15));
[path applyTransform:rotate];
// CGAffineTransform translate = CGAffineTransformMakeTranslation(-110, 70); // -45
CGAffineTransform translate = CGAffineTransformMakeTranslation(-52, -58); // -15
[path applyTransform:translate];
However, the ratios of x/y translations do not correspond so I cannot extrapolate what translation is required based on the angle. It appears that 'CGAffineTransformMakeRotation' uses some arbitrary anchor put to make the rotation, which at the moment appears to be maybe (viewWidth / 2, 0). I am making this much harder than it needs to be. There's something I am missing to make a simple rotation so that the center point is maintained. I just need to "spin" the path 90 degrees left or right.
UPDATE #5 12/4/2012 - After running additional tests it appears that the anchor point for rotating a UIBezierPath is the origin from where all of the points were drawn. In this case the origin is 0,0 and all of the points are relative to that point. Therefore, it a rotation is applied, the rotation is occurring around the origin, and is why the path shifts up-right on -90 and up-left on 90. I need to somehow set the anchor point for the rotation to the center so it "spins" around the center, rather than the original origin point. 12 hours spent on this one issue.
After some detailed analysis and graphing the bounding box on paper I found my assertion that the origin of 0,0 is correct.
A solution to this problem is to translate the path (the underlying matrix) to the origin, with the center of the bounding box at origin, rotate, then translate the path back to its original location.
Here's how to rotate a UIBezierPath 90 degrees:
CGAffineTransform translate = CGAffineTransformMakeTranslation(-1 * (box.origin.x + (box.size.width / 2)), -1 * (box.origin.y + (box.size.height / 2)));
[path applyTransform:translate];
CGAffineTransform rotate = CGAffineTransformMakeRotation(DegreesToRadians(90));
[path applyTransform:rotate];
translate = CGAffineTransformMakeTranslation((box.origin.x + (box.size.width / 2)), (box.origin.y + (box.size.height / 2)));
[path applyTransform:translate];
Plug in -90 degrees to rotate in the other direction.
This formula can be used when rotating the device from portrait to landscape and vice/versa.
I still don't think this is the ideal solution but the result is what I need for now.
If anyone has a better solution for this please post.
UPDATE 12/7/2012 - I found what I think is the best solution, and very simple as I though it would be. Rather than using rotate, translate, and scale methods on the bezier path, I instead extract the array of points as CGPoint objects, and scale/translate them as needed based on the view size as well as the orientation. I then create a new bezier path and set the layer to this path.
The result is perfect scaling, translation, rotation.
You will notice the red "+" / "arrows" glyph in the attached screenshot. It is easy enough to change this "origin" point in Xcode. Is there also a way to do this programmatically or is this entirely an Xcode abstraction?
For instance, I want to programmatically create a UILabel and position it by calculating the lower right hand coordinate. In Xcode, I would simply make sure that the red "+" is on the bottom right grid point and define the X, Y, Width and Height parameters with that "origin" in mind.
If you're not using autolayout, you can position a label (or any view) in code by setting its center. So if you know where you want the label's lower right corner to be, you can just subtract half the width and height of the label to compute where its center should be:
CGPoint lowerRight = somePoint;
CGRect frame = label.frame;
label.center = CGPointMake(lowerRight.x - frame.size.width / 2,
lowerRight.y - frame.size.height / 2);
I would recommend just doing that.
But if you want, you can instead go to a lower level. Every view has a Core Animation layer, which is what actually manages the view's on-screen appearance. The layer has an anchorPoint property, which by default is (0.5, 0.5), representing the center of the layer. You can set the anchorPoint to (1, 1) for the lower-right corner:
label.layer.anchorPoint = CGPointMake(1, 1);
Now the label's center actually controls the location of its lower right corner, so you can set it directly:
label.center = somePoint; // actually sets the lower right corner
You'll need to add the QuartzCore framework to your target and import <QuartzCore/QuartzCore.h> to modify the anchorPoint property.
myObject.origin = CGPointMake (0.0,0.0);