I am doing a module where there is a pin drop functionality.
The pin[Image view] is dropped on a scroll view which is zoom-able.
When zoomed the the image view moves in accordance with its center orgin.
I would like to make it moved with its bottom point.
- (void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(float)scale;
{
zoomLevel=scale;
for (SSSmartPinView *smartPinView in smartPinViewMutArray) {
smartPinView.zoomScale = zoomLevel;
smartPinView.parrentOffset = drawingScrollView.contentOffset;
smartPinView.center = CGPointMake(([smartPinView.coresmartPin.xpoint floatValue]*zoomLevel),(([smartPinView.coresmartPin.ypoint floatValue]+(zoomLevel))*zoomLevel));
}
}
- (void)scrollViewDidZoom:(UIScrollView *)scrollView{
zoomLevel=scrollView.zoomScale;
for (SSSmartPinView *smartPinView in smartPinViewMutArray){
smartPinView.zoomScale = zoomLevel;
smartPinView.parrentOffset = drawingScrollView.contentOffset;
smartPinView.center = CGPointMake(([smartPinView.coresmartPin.xpoint floatValue]*zoomLevel),(([smartPinView.coresmartPin.ypoint floatValue]+(zoomLevel))*zoomLevel));
}
}
You can set the anchor (center point for rotation / scaling) with
smartPinView.layer.anchorPoint = CGPointMake(0.5, 1.0);
See the anchorPoint property
Related
I have two UIScrollViews. Both the scroll views contain an image. Now, I want to zoom second scroll view programmatically if I zoom in the first scroll view manually. I am using -(UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView method to manually zoom the first scroll view. The second scroll view should be zoomed to the same point and scale. How can I achieve this?
By using the tag or object of those two scrollviews you can identify the which scroll view you need zoom in viewForZoomingInScrollView method.
e.g
//need to set the tag for scrollviews
-(UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
if(scrollView.tag == 1)
{
return firstImageView;
}
return secondImageView;
}
OR
//need to create the object of used scrollviews
-(UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
if(scrollView == objScrollViewFirst)
{
return firstImageView;
}
return secondImageView;
}
How about something like this:
CGRect zoomRect;
zoomRect.size.height = manualScrollView.frame.size.height / manualScrollView.zoomScale;
zoomRect.size.width = manualScrollView.frame.size.width / manualScrollView.zoomScale;
zoomRect.origin.x = manualScrollView.center.x - (zoomRect.size.width / 2.0);
zoomRect.origin.y = manualScrollView.center.y - (zoomRect.size.height / 2.0);
[autoScrollView zoomToRect:zoomRect animated:YES];
[autoScrollView setZoomScale:manualScrollView.zoomScale animated:YES];
Try something like this in the UIScrollViewDelegate method:
override func scrollViewDidScroll(scrollView: UIScrollView){
otherScrollView.contentOffset = scrollView.contentOffset
otherScrollView.zoomScale = scrollView.zoomScale
}
I am using a UITableView to achieve a scale/unblur effect on my user's profile picture (like in the Spotify App) when I pull down the UITableView to a negative contentOffset.y. This all works fine...
Now, when a user pulls down to a contentOffset.y smaller or equal to a certain value -let's call it maintainOffsetY = 70.0- and he "lets go" of the view, I would like to maintain this contentOffset until the user "pushes" the view up again, instead of the view to automatically bounce back to contentOffset = (0,0) again.
In order to achieve this, I must know when the touches began and ended, which I can do with the following delegate methods:
- (void) scrollViewWillBeginDragging:(UIScrollView *)scrollView {
// is like touches begin
if ([scrollView isEqual:_tableView]) {
NSLog(#"touches began");
_touchesEnded = NO;
}
}
- (void) scrollViewWillEndDragging:(UIScrollView *)scrollView withVelocity:(CGPoint)velocity targetContentOffset:(inout CGPoint *)targetContentOffset {
// is like touches ended
NSLog(#"touches ended");
if ([scrollView isEqual:_tableView]) {
_touchesEnded = YES;
}
}
Then in
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
I check if the contentOffset.y is smaller than or equal to maintainOffsetY and if the user has already "let go" of the table, so it is about to bounce (or already bouncing) back to contentOffset = (0,0).
It does not seem to be possible to let it bounce back only to the maintainOffsetY. Does anybody know a workaround or have an idea on how to solve this?
Any help is much appreciated!
To set a negative offset to a scroll view you can use this.
You need to save the initial content inset of scroll view. It can be not 0 already, if you have translucent nav bar for example.
- (void)viewDidAppear:(BOOL)animated {
[super viewDidAppear:animated];
contentInsetTopInitial = self.tableView.contentInset.top;
}
Then write this.
- (void)scrollViewWillEndDragging:(UIScrollView *)scrollView withVelocity:(CGPoint)velocity targetContentOffset:(inout CGPoint *)targetContentOffset {
CGPoint contentOffset = scrollView.contentOffset; // need to save contentOffset before changing contentInset
CGFloat contentOffsetY = contentOffset.y + contentInsetTopInitial; // calculate pure offset, without inset
if (contentOffsetY < -maintainOffsetY) {
scrollView.contentInset = UIEdgeInsetsMake(contentInsetTopInitial + maintainOffsetY, 0, maintainOffsetY, 0);
[scrollView setContentOffset:contentOffset animated:NO];
}
}
Hope this will help.
I'm having a lot of trouble figuring out how best to reposition my UIScrollView's image view (I have a gallery kind of app going right now, similar to Photos.app, specifically when you're viewing a single image) when the orientation switches from portrait to landscape or vice-versa.
I know my best bet is to manipulate the contentOffset property, but I'm not sure what it should be changed to.
I've played around a lot, and it seems like for whatever reason 128 works really well. In my viewWillLayoutSubviews method for my view controller I have:
if (UIInterfaceOrientationIsLandscape([UIApplication sharedApplication].statusBarOrientation)) {
CGPoint newContentOffset = self.scrollView.contentOffset;
if (newContentOffset.x >= 128) {
newContentOffset.x -= 128.0;
}
else {
newContentOffset.x = 0.0;
}
newContentOffset.y += 128.0;
self.scrollView.contentOffset = newContentOffset;
}
else {
CGPoint newContentOffset = self.scrollView.contentOffset;
if (newContentOffset.y >= 128) {
newContentOffset.y -= 128.0;
}
else {
newContentOffset.y = 0.0;
}
newContentOffset.x += 128.0;
self.scrollView.contentOffset = newContentOffset;
}
And it works pretty well. I hate how it's using a magic number though, and I have no idea where this would come from.
Also, whenever I zoom the image I have it set to stay centred (just like Photos.app does):
- (void)centerScrollViewContent {
// Keep image view centered as user zooms
CGRect newImageViewFrame = self.imageView.frame;
// Center horizontally
if (newImageViewFrame.size.width < CGRectGetWidth(self.scrollView.bounds)) {
newImageViewFrame.origin.x = (CGRectGetWidth(self.scrollView.bounds) - CGRectGetWidth(self.imageView.frame)) / 2;
}
else {
newImageViewFrame.origin.x = 0;
}
// Center vertically
if (newImageViewFrame.size.height < CGRectGetHeight(self.scrollView.bounds)) {
newImageViewFrame.origin.y = (CGRectGetHeight(self.scrollView.bounds) - CGRectGetHeight(self.imageView.frame)) / 2;
}
else {
newImageViewFrame.origin.y = 0;
}
self.imageView.frame = newImageViewFrame;
}
So I need it to keep it positioned properly so it doesn't show black borders around the image when repositioned. (That's what the checks in the first block of code are for.)
Basically, I'm curious how to implement functionality like in Photos.app, where on rotate the scrollview intelligently repositions the content so that the middle of the visible content before the rotation is the same post-rotation, so it feels continuous.
You should change the UIScrollView's contentOffset property whenever the scrollView is layouting its subviews after its bounds value has been changed. Then when the interface orientation will be changed, UIScrollView's bounds will be changed accordingly updating the contentOffset.
To make things "right" you should subclass UIScrollView and make all the adjustments there. This will also allow you to easily reuse your "special" scrollView.
The contentOffset calculation function should be placed inside UIScrollView's layoutSubviews method. The problem is that this method is called not only when the bounds value is changed but also when srollView is zoomed or scrolled. So the bounds value should be tracked to hint if the layoutSubviews method is called due to a change in bounds as a consequence of the orientation change, or due to a pan or pinch gesture.
So the first part of the UIScrollView subclass should look like this:
- (id)initWithFrame:(CGRect)frame {
self = [super initWithFrame:frame];
if (self) {
// Set the prevBoundsSize to the initial bounds, so the first time
// layoutSubviews is called we won't do any contentOffset adjustments
self.prevBoundsSize = self.bounds.size;
}
return self;
}
- (void)layoutSubviews {
[super layoutSubviews];
if (!CGSizeEqualToSize(self.prevBoundsSize, self.bounds.size)) {
[self _adjustContentOffset];
self.prevBoundsSize = self.bounds.size;
}
[self _centerScrollViewContent];
}
Here, the layoutSubviews method is called every time the UIScrollView is panned, zoomed or its bounds are changed. The _centerScrollViewContent method is responsible for centering the zoomed view when its size becomes smaller than the size of the scrollView's bounds. And, it is called every time user pans or zooms the scrollView, or rotates the device. Its implementation is very similar to the implementation you provided in your question. The difference is that this method is written in the context of UIScrollView class and therefore instead of using self.imageView property to reference the zoomed view, which may not be available in the context of UIScrollView class, the viewForZoomingInScrollView: delegate method is used.
- (void)_centerScrollViewContent {
if ([self.delegate respondsToSelector:#selector(viewForZoomingInScrollView:)]) {
UIView *zoomView = [self.delegate viewForZoomingInScrollView:self];
CGRect frame = zoomView.frame;
if (self.contentSize.width < self.bounds.size.width) {
frame.origin.x = roundf((self.bounds.size.width - self.contentSize.width) / 2);
} else {
frame.origin.x = 0;
}
if (self.contentSize.height < self.bounds.size.height) {
frame.origin.y = roundf((self.bounds.size.height - self.contentSize.height) / 2);
} else {
frame.origin.y = 0;
}
zoomView.frame = frame;
}
}
But the more important thing here is the _adjustContentOffset method. This method is responsible for adjusting the contentOffset. Such that when UIScrollView's bounds value is changed the center point before the change will remain in center. And because of the condition statement, it is called only when UIScrollView's bounds is changed (e.g.: orientation change).
- (void)_adjustContentOffset {
if ([self.delegate respondsToSelector:#selector(viewForZoomingInScrollView:)]) {
UIView *zoomView = [self.delegate viewForZoomingInScrollView:self];
// Using contentOffset and bounds values before the bounds were changed (e.g.: interface orientation change),
// find the visible center point in the unscaled coordinate space of the zooming view.
CGPoint prevCenterPoint = (CGPoint){
.x = (self.prevContentOffset.x + roundf(self.prevBoundsSize.width / 2) - zoomView.frame.origin.x) / self.zoomScale,
.y = (self.prevContentOffset.y + roundf(self.prevBoundsSize.height / 2) - zoomView.frame.origin.y) / self.zoomScale,
};
// Here you can change zoomScale if required
// [self _changeZoomScaleIfNeeded];
// Calculate new contentOffset using the previously calculated center point and the new contentOffset and bounds values.
CGPoint contentOffset = CGPointMake(0.0, 0.0);
CGRect frame = zoomView.frame;
if (self.contentSize.width > self.bounds.size.width) {
frame.origin.x = 0;
contentOffset.x = prevCenterPoint.x * self.zoomScale - roundf(self.bounds.size.width / 2);
if (contentOffset.x < 0) {
contentOffset.x = 0;
} else if (contentOffset.x > self.contentSize.width - self.bounds.size.width) {
contentOffset.x = self.contentSize.width - self.bounds.size.width;
}
}
if (self.contentSize.height > self.bounds.size.height) {
frame.origin.y = 0;
contentOffset.y = prevCenterPoint.y * self.zoomScale - roundf(self.bounds.size.height / 2);
if (contentOffset.y < 0) {
contentOffset.y = 0;
} else if (contentOffset.y > self.contentSize.height - self.bounds.size.height) {
contentOffset.y = self.contentSize.height - self.bounds.size.height;
}
}
zoomView.frame = frame;
self.contentOffset = contentOffset;
}
}
Bonus
I've created a working SMScrollView class (here is link to GitHub) implementing the above behavior and additional bonuses:
You can notice that in Photos app, zooming a photo, then scrolling it to one of its boundaries and then rotating the device does not keep the center point in its place. Instead it sticks the scrollView to that boundary. And if you scroll to one of the corners and then rotate, the scrollView will be stick to that corner as well.
In addition to adjusting contentOffset you may find that you also want to adjust the scrollView's zoomScale. For example, assume you are viewing a photo in portrait mode that is scaled to fit the screen size. Then when you rotate the device to the landscape mode you may want to upscale the photo to take advantage of the available space.
I'm using storyboard (iOS 6.0) to create a photo gallery viewer for my app. This is how my imageViewController is set up in storyboard:
I've made sure to enable userInteraction and multiple touches on both the imageView and scrollView. What I want to do is, on pinch I want to zoom into the imageView (maximum scale 3) and be able to pan around. This is what I currently have, however, even though the pinch gesture is detected the scale does not change.
- (IBAction)imagePinched:(id)sender {
if (pinchRecognizer.state == UIGestureRecognizerStateEnded || pinchRecognizer.state == UIGestureRecognizerStateChanged) {
NSLog(#"gesture.scale = %f", pinchRecognizer.scale);
CGFloat currentScale = self.fullScreenView.frame.size.width / self.fullScreenView.bounds.size.width;
CGFloat newScale = currentScale * pinchRecognizer.scale;
if (newScale < 1) {
newScale = 1;
}
if (newScale > 3) {
newScale = 3;
}
CGAffineTransform transform = CGAffineTransformMakeScale(newScale, newScale);
self.fullScreenView.transform = transform;
pinchRecognizer.scale = 1;
}
}
Most questions and tutorials online deal with programmatically creating the views and doing this, but the less code the better (in my eyes). What's the best way to get this to work with storyboard? Thank you in advance!!!
UPDATED:
Here is my full .m file code:
- (void)viewDidLoad
{
[super viewDidLoad];
//Assign an image to this controller's imageView
fullScreenView.image = [UIImage imageNamed:imageString];
//Allows single and double tap to work
[singleTapRecognizer requireGestureRecognizerToFail: doubleTapRecognizer];
}
- (IBAction)imageTapped:(id)sender {
NSLog(#"Image Tapped.");
//On tap, fade out viewController like the twitter.app
[self dismissViewControllerAnimated:YES completion:nil];
}
- (IBAction)imageDoubleTapped:(id)sender {
NSLog(#"Image Double Tapped.");
//On double tap zoom into imageView to fill in the screen.
[fullScreenView setContentMode:UIViewContentModeScaleAspectFill];
}
- (IBAction)imagePinched:(id)sender {
if (pinchRecognizer.state == UIGestureRecognizerStateEnded || pinchRecognizer.state == UIGestureRecognizerStateChanged) {
NSLog(#"gesture.scale = %f", pinchRecognizer.scale);
CGFloat currentScale = self.fullScreenView.frame.size.width / self.fullScreenView.bounds.size.width;
CGFloat newScale = currentScale * pinchRecognizer.scale;
if (newScale < 1) {
newScale = 1;
}
if (newScale > 3) {
newScale = 3;
}
CGAffineTransform transform = CGAffineTransformMakeScale(newScale, newScale);
self.fullScreenView.transform = transform;
pinchRecognizer.scale = 1;
}
}
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
return self.fullScreenView;
}
-(void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(float)scale {
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#end
I think better solution in Apple Documentation
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
return self.imageView;
}
- (void)viewDidLoad {
[super viewDidLoad];
self.scrollView.minimumZoomScale=0.5;
self.scrollView.maximumZoomScale=6.0;
self.scrollView.contentSize=CGSizeMake(1280, 960);
self.scrollView.delegate=self;
}
Check Apple Documentation
The first step is to make sure your views have the correct delegates implemented. For example in the .m file
#interface myRootViewController () <.., UIGestureRecognizerDelegate, UIScrollViewDelegate, ...>
From the documentation, make sure you have this implemented:
The UIScrollView class can have a delegate that must adopt the UIScrollViewDelegate protocol. For zooming and panning to work, the delegate must implement both viewForZoomingInScrollView: and scrollViewDidEndZooming:withView:atScale:; in addition, the maximum (maximumZoomScale) and minimum ( minimumZoomScale) zoom scale must be different.
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
return self.fullScreenView;
}
-(void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(float)scale
{}
The scrollViewDidEndZooming method can stay empty for now. If you already did that or it still doesnt work, please post more of your code and then it is easier to help more specifically.
You need to do what Wadi suggested above but also set the setMinimumZoomScale to be different from setMaximumZoomScale. They are both 1.0f by default.
After that, the UIImageView should be pinchable
I have created a fully working demo application (similar in nature to Facebook's default photo gallery) which demonstrates pinch to zoom of Image View nested inside a scroll view with AutoLayout and storyboards. View my project here: http://rexstjohn.com/facebook-like-ios-photo-modal-gallery-swipe-gestures/.
It also includes async photo loading via MKNetworkKit and gesture based swiping through a photo gallery. Enjoy and I hope it saves everyone time trying to figure this out because it is somewhat annoying.
Here is how Apple recomends to do what you want to do. I used the code provided by Apple and it worked like a charm! If you want to optimize memory management, you can use iCarousel (made by nicklockwood), which have a cache management for dealloc unused views!
I've created a class to handle zooming of UIImageViews similar to Instagram. Might be what you're looking for, otherwise you can look at how I achieved it. https://github.com/twomedia/TMImageZoom
In my iPad app, Universal Combat Log (new-layout branch), I have a UIView subclass (UCLLineChartView) which contains a UIScrollView and the scrollview in turn contains another UIView subclass (ChartView). ChartView has multiple sub-layers, one for each line of data that has been added to the chart. UCLLineChartView draws the axes and markers. The contents of these views/layers are entirely custom drawn, no stock views are used (e.g. UIImageView).
I'm having a problem with zooming -- it's scaling the ChartView like an image, which makes the drawn line all blurred and stretched. I want the line to stay sharp, preferably even while the user is in the act of zooming, but after 3 days of hacking at this, I cannot get it to work.
If I override setTransform on the ChartView to grab the scale factor from the transform but don't call [super setTransform], then the scrollview's zoomScale stays at 1. I tried keeping the given transform and overriding the transform method to return it. I tried replicating the effects of setTransform by changing the ChartView's center and bounds but I wasn't able to get the behaviour quite right and it still didn't seem to affect the scrollview's zoomScale. It seems that the scrollview's zoomScale depends on the effects of setTransform, but I cannot determine how.
Any assistance would be greatly appreciated.
What you will need to do is update the contentScaleFactor of the chartView. You can do that by adding the following code in either scrollViewDidEndZooming:withView:atScale: or scrollViewDidZoom:.
CGFloat newScale = scrollView.zoomScale * [[UIScreen mainScreen] scale];
[self.chartView setContentScaleFactor:newScale];
I have figured out a solution to my problem that is not too gross a hack. In your UIScrollViewDelegate:
- (void)scrollViewWillBeginZooming:(UIScrollView *)scrollView withView:(UIView *)view
{
[_contentView beginZoom];
}
- (void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(float)scale
{
CGSize size = scrollView.bounds.size;
CGPoint contentOffset = _scrollView.contentOffset;
CGFloat newScale = _contentView.scale;
newScale = MAX(newScale, kMinZoomScale);
newScale = MIN(newScale, kMaxZoomScale);
[_scrollView setZoomScale:1.0 animated:NO];
_scrollView.minimumZoomScale = kMinZoomScale / newScale;
_scrollView.maximumZoomScale = kMaxZoomScale / newScale;
_contentView.scale = newScale;
CGSize newContentSize = CGSizeMake(size.width * newScale, size.height);
_contentView.frame = CGRectMake(0, 0, newContentSize.width, newContentSize.height);
_scrollView.contentSize = newContentSize;
[_scrollView setContentOffset:contentOffset animated:NO];
[_contentView updateForNewSize];
[_contentView setNeedsDisplay];
}
In your content view, declare a scale property and the following methods:
- (void)beginZoom
{
_sizeAtZoomStart = CGSizeApplyAffineTransform(self.frame.size, CGAffineTransformMakeScale(1/self.scale, 1));
_scaleAtZoomStart = self.scale;
}
- (void)setTransform:(CGAffineTransform)transform
{
self.scale = _scaleAtZoomStart * transform.a;
self.frame = CGRectMake(0, 0, _sizeAtZoomStart.width * self.scale, _sizeAtZoomStart.height);
[self updateForNewSize];
[self setNeedsDisplay];
}
And if your content view uses sub-layers, you'll need to disable their implicit animations by adding the following to the sub-layers' delegate(s):
- (id<CAAction>)actionForLayer:(CALayer *)layer forKey:(NSString *)event
{
// prevent animation of the individual layers so that zooming doesn't cause weird jitter
return (id<CAAction>)[NSNull null];
}
The basic idea here is that the overridden setTransform uses the scale factor from the tranform matrix to calculate the new scale factor for the content view and then resizes the content view accordingly. The scrollview automatically adjusts the content offset to keep the content view centered.
The scrollViewDidEndZooming code keeps the zooming bounded.
There are further complexities for dealing with resizing the scrollview when rotating device for example.