I am trying to rotate an image. This I am succeeding in doing. The problem is that when I am clicking down and dragging slightly, the image rotates completely to reach the point where I have clicked and then rotates slowly as I drag the image clockwise. I am concerned to why it is rotating completely to the place that I am dragging. I want the dragging to start from the position it is found and NOT to rotate to the place my finger is down on and then starts from there.
This is my code:
-
(void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
}
-(void) touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
NSSet *allTouches = [event allTouches];
int len = [allTouches count]-1;
UITouch *touch =[[allTouches allObjects] objectAtIndex:len];
CGPoint location = [touch locationInView:[self superview]];
float theAngle = atan2( location.y-self.center.y, location.x-self.center.x );
totalRadians = theAngle;
[self rotateImage:theAngle];
}
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
}
-(void) rotateImage:(float)angleRadians{
self.transform = CGAffineTransformMakeRotation(angleRadians);
CATransform3D rotatedTransform = self.layer.transform;
self.layer.transform = rotatedTransform;
}
Am I doing anything wrong?
Thanks!
Instead of creating the transformation from the angle that your getting from the touch, try incrementing totalRadians by its difference from the new angle, and then create the transform from that.
-(void) touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
NSSet *allTouches = [event allTouches];
int len = [allTouches count]-1;
UITouch *touch =[[allTouches allObjects] objectAtIndex:len];
CGPoint location = [touch locationInView:[self superview]];
float theAngle = atan2( location.y-self.center.y, location.x-self.center.x );
totalRadians += fabs(theAngle - totalRadians);
totalRadians = fmod(totalRadians, 2*M_PI);
[self rotateImage:totalRadians];
}
My first advice would be to switch to using the UIRotateGestureRecognizer if your app is for 4.0 and higher. It does the right thing and provides you with a rotation property.
Related
I want to determine whether the tapped location is in region or not. I have 4 CGPoints and I know this can be done by using UITouch. Also, I have screen tapped location by using the function
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *myTouch = [[touches allObjects] objectAtIndex: 0];
CGPoint currentPos = [myTouch locationInView:self.view];
}
And for example my 4 CGPoints are
self.firstPoint = CGPointMake(50.0f, 50.0f);
self.secondPoint = CGPointMake(200.0, 50.0);
self.thirdPoint = CGPointMake(200.0, 200.0);
self.fourthPoint = CGPointMake(50.0, 120.0);
Thanks in advance
You should use a CGRect to represent the rect instead of four CGPoints and then use CGRectContainsPoint() to check if the rect contains the point.
-(void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
UITouch *touch = [[event allTouches] anyObject];
CGPoint location = [touch locationInView:touch.view];
image=[UIImage imageNamed:#"anyImage.gif"];
newView = [[UIImageView alloc]initWithImage:image];
if (location.y<480|| location.y>50)
{
//write your code
}
}
I have an image at the bottom of the screen.
I want the user to to move the image upwards until it reaches a certain Y point as follows:
[door setCenter:CGPointMake(160,347)];
So far, as you drag the image (door) upwards it continues past my destination point but when you let go it snaps back to the correct position.
How do I stop the image moving when reaching a certain point if the user's finger is still swiping upwards? Would it be inside an if statement?
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
if (startPoint.y < 347) {
// something in here ?????
}
}
-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{
UITouch *myTouch = [touches anyObject];
startPoint = [myTouch locationInView:self.view];
NSLog(#"position = %f and %f",startPoint.x,startPoint.y);
[door setCenter:CGPointMake(160, startPoint.y)];
}
-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event{
[door setCenter:CGPointMake(160,347)];
}
How about setting it in touchesMoved method. Something like,
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{
UITouch *myTouch = [touches anyObject];
startPoint = [myTouch locationInView:self.view];
NSLog(#"position = %f and %f",startPoint.x,startPoint.y);
if (startPoint.y < 347) { //or suitable condition to verify your case
[door setCenter:CGPointMake(160, startPoint.y)]; //then only set the center
} else
{
[door setCenter:CGPointMake(160,347);
}
}
I have written a custom UIGestureRecognizer which handles rotations with one finger. It is designed to work exactly like Apples UIRotationGestureRecognizer and return the same values as it does.
Now, I would like to implement the velocity but I cannot figure out how Apple defines and calculates the velocity for the gesture recognizer.
Does anybody have an idea how Apple implements this in the UIRotationGestureRecognizer?
You would have to keep reference of last touch position and it's timestamp.
double last_timestamp;
CGPoint last_position;
Then you could do something like:
-(void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{
last_timestamp = CFAbsoluteTimeGetCurrent();
UITouch *aTouch = [touches anyObject];
last_position = [aTouch locationInView: self];
}
-(void) touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
double current_time = CFAbsoluteTimeGetCurrent();
double elapsed_time = current_time - last_timestamp;
last_timestamp = current_time;
UITouch *aTouch = [touches anyObject];
CGPoint location = [aTouch locationInView:self.superview];
CGFloat dx = location.x - last_position.x;
CGFloat dy = location.y - last_position.y;
CGFloat path_travelled = sqrt(dx*dx+dy*dy);
CGFloat sime_kind_of_velocity = path_travelled/elapsed_time;
NSLog (#"v=%.2f", sime_kind_of_velocity);
last_position = location;
}
This should give you some kind of speed reference.
I'm making a simple dial that rotates as you drag your finger across it. It rotates great, but it also rotates when i touch anywhere on the screen and drag my finger.
How can i restrict the first touches to be only inside my imageview object? or where am i going wrong?
this is my code of trouble:
- (id)initWithFrame:(CGRect)frame {
self = [super initWithFrame:frame];
if (self) {
UIImage *image1 = [UIImage imageNamed:#"nav#2x.png"];
wheelfrom = [[UIImageView alloc] initWithImage:image1];
wheelfrom.frame =CGRectMake(10, -130, 300, 300);
[self addSubview:wheelfrom];
}
return self;
}
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{
UITouch *touch =[[[event allTouches] allObjects] lastObject];
firstLoc = [touch locationInView:self];
}
-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{
UITouch *touch =[[[event allTouches] allObjects] lastObject];
CGPoint curLoc = [touch locationInView:self];
float fromAngle = atan2( firstLoc.y-wheelfrom.center.y,
firstLoc.x-wheelfrom.center.x );
float toAngle = atan2( curLoc.y-wheelfrom.center.y,
curLoc.x-wheelfrom.center.x );
float newAngle = angle + (toAngle - fromAngle);
CGAffineTransform cgaRotate = CGAffineTransformMakeRotation(newAngle);
wheelfrom.transform = cgaRotate;
angle = newAngle;
}
Thanks for your help!
You try like this,
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [[event allTouches] anyObject];
CGPoint location = [touch locationInView:self.view];
if(CGRectContainsPoint(wheelfrom.frame, location))
{
//do your things
}
}
You can try by checking if the point of touch is within the frame of the image view.Do what you want only if its yes.
Inside -(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event, check the firstLoc is within your range.
I am trying to implement a selection wheel in an iphone application. I have got the wheel to track the users finger but now for some reason when the user touches the screen the wheel jumps so the same section of the wheel tracks the finger each time.
How would I get it so the wheel rotates like the user is dragging it from any point?
-(void) touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
NSSet *allTouches = [event allTouches];
int tInput = [allTouches count]-1;
UITouch *touch =[[allTouches allObjects] objectAtIndex:tInput];
CGPoint location = [touch locationInView:self.view];
float theAngle = atan2( location.y-imageX.center.y, location.x-imageX.center.x );
CGAffineTransform cgaRotate = CGAffineTransformMakeRotation(theAngle);
imageX.transform = cgaRotate;
}
Any suggestion?
Right - that makes perfect sense - this is indeed what your code does.
What you need to add is the initial value where you started your drag as a relative rotation -- or track your last rotation.
A very elaborate way is shown below - but this should help get the point across.
#interface UntitledViewController : UIViewController {
CGPoint firstLoc;
UILabel * fred;
double angle;
}
#property (assign) CGPoint firstLoc;
#property (retain) UILabel * fred;
#implementation UntitledViewController
#synthesize fred,firstLoc;
- (void)viewDidLoad {
[super viewDidLoad];
self.fred = [[UILabel alloc] initWithFrame:CGRectMake(100,100,100,100)];
fred.text = #"Fred!"; fred.textAlignment = UITextAlignmentCenter;
[self.view addSubview:fred];
angle = 0; // we aint have rotated just yet...
};
// make sure we get them drag events.
- (BOOL)isFirstResponder { return YES; }
-(void)handleObject:(NSSet *)touches
withEvent:(UIEvent *)event
isLast:(BOOL)lst
{
UITouch *touch =[[[event allTouches] allObjects] lastObject];
CGPoint curLoc = [touch locationInView:self.view];
float fromAngle = atan2( firstLoc.y-fred.center.y,
firstLoc.x-fred.center.x );
float toAngle = atan2( curLoc.y-fred.center.y,
curLoc.x-fred.center.x );
// So the angle to rotate to is relative to our current angle and the
// angle through which our finger moved (to-from)
float newAngle = angle + (toAngle - fromAngle);
CGAffineTransform cgaRotate = CGAffineTransformMakeRotation(newAngle);
fred.transform = cgaRotate;
// we only 'save' the current angle when we're done with the drag.
//
if (lst)
angle = newAngle;
}
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
UITouch *touch =[[[event allTouches] allObjects] lastObject];
// capture where we started - so we can later work out the
// rotation relative to this point.
//
firstLoc = [touch locationInView:self.view];
};
-(void) touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
[self handleObject:touches withEvent:event isLast:NO];
};
-(void) touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
[self handleObject:touches withEvent:event isLast:YES];
}
Obviously you can do this a lot more elegant - and above misses a bit of 0 .. 2xPI capping you need.
Because the view itself is still the old one. You may want to fetch the zip example file in:
http://bynomial.com/blog/?p=77
and in PuttyView.m change the:
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
....
else {
self.center = CGPointMake(self.center.x + touchPoint.x - touchStart.x,
self.center.y + touchPoint.y - touchStart.y);
into
else {
NSSet *allTouches = [event allTouches];
int tInput = [allTouches count]-1;
UITouch *touch =[[allTouches allObjects] objectAtIndex:tInput];
CGPoint location = [touch locationInView:self];
float theAngle = atan2( location.y-self.center.y, location.x-self.center.x );
CGAffineTransform cgaRotate = CGAffineTransformMakeRotation(theAngle);
self.transform = cgaRotate;
}
where you thus stay within the view and its relative angle. Alternatively - in your code - keep the relative angle itself.