How can i restrict the pinching effect only on X-axis. ?
I've created a ScrollView and added an image into it . I've already done the pinch zoom effect for the UIImageView but i want to restrict the zoom only on X-axis.
Try this :
1. Use UIScrollViewDelegate
2. Implement this function
-(void)scrollViewDidScroll:(UIScrollView *)scrollView
{
if (scrollView.contentOffset.x > 0)
scrollView.pinchGestureRecognizer.enabled = YES;
else
scrollView.pinchGestureRecognizer.enabled = NO;
}
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've a UIScrollView with other subviews inside an UIImageWiew and I need to rotate the whole content, so I take this road:
imageView.transform = CGAffineTransformMakeRotation([self.orientation floatValue]);
Good, works perfectly.
Being the ImageView inside a scroll view, I also need to set zoomScale in order to resize image inside, and I do it in this way:
- (void)updateZoom {
const float minZoom = MIN(self.view.bounds.size.width / self.imageView.image.size.width,
self.view.bounds.size.height / self.imageView.image.size.height);
if (minZoom > 1) {
return;
}
self.scrollView.minimumZoomScale = minZoom;
self.scrollView.zoomScale = minZoom;
}
updateZoom has the effect to "reset" initial transformation, so image come back to original orientation.
Generally, each time I modify "zoomScale" property, orientation is restored.
How can I keep both orientation both zoomScale?
I suppose I need to do something in scrollView delegate:
- (void)scrollViewDidZoom:(UIScrollView *)scrollView;
I just put a repo on GitHub that might help you. It is in Swift but it should do
PhotoSlideShow-Swift
I have a pageable UIScrollView which contains different kind of informations like UITables but also zoomable images. Therefore I set up a pageable main-ScrollView and as subviews I added zoomable image-ScrollViews with the images as content.
Works everything fine, just I fail to set the smaller current zoom scale of the imageScrollViews.
UIImageView *imageView = [[UIImageView alloc] initWithImage:Image];
//storing a link to the imageView
[imagelinkArray addObject:imageView];
CGRect ScrollViewImageRect;
ScrollViewImageRect = CGRectMake((self.scrollView.frame.size.width) * i, 0, 320, self.scrollView.frame.size.height);
float widthfactor = ScrollViewImageRect.size.width / imageView.frame.size.width;
float heightfactor = ScrollViewImageRect.size.height / imageView.frame.size.height;
float zoomscale = MIN(widthfactor, heightfactor);
UIScrollView *imageScrollView = [[UIScrollView alloc] initWithFrame:ScrollViewImageRect];
imageScrollView.contentSize = CGSizeMake(imageView.frame.size.width, imageView.frame.size.height);
imageScrollView.delegate = self;
[imageScrollView setMinimumZoomScale:zoomscale];
[imageScrollView setMaximumZoomScale:1.5];
[imageScrollView addSubview:imageView];
//doesn't work:
[imageScrollView setZoomScale:0.5 animated:YES];
[self.scrollView addSubview:imageScrollView];
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
return [imagelinkArray objectAtIndex:page];
}
The main-ScrollView and the image-ScrollViews are drawn perfectly and it's possible to zoom and page properly. The minimum zoom factor is calculated also correct. When I zoom out I can zoom until the image limits are reached. However the first time I page to the image-ScrollView it's current zoom scale is always 1.0 while it should be the minimum scale.
Wherever I set the zoom scale in the code above it doesn't work:
[changeScrollView setZoomScale:changeScrollView.minimumZoomScale animated:YES];
If I log the current zoom scale i always get 1.0;
The only thing which works is changing the zoom scale in the - (void)scrollViewDidScroll: method, which of course doesn't help a lot since zooming also calls it which resets the zoom immediately. But at least I could figure out, that the code somehow works. I have the feeling a UIScrollView doesn't zoom when it's not visible on the screen right now. How can I fix this?
Update:
Okay. In the meantime I figured out that the problem most likely comes from my base layout of "sub-viewing" ScrollViews into another ScrollView. When I zoom one of the images and log the current zoom factor of the ScrollViews they are all the same (main ScrollView as well as ALL sub-ScrollViews).
What could be the reason for it or how could I solve it with a different layout?
I think viewForZoomingInScrollView: may not be getting called by the scrollview. Try to add a breakpoint and check what you're returning there.
Your code doesn't work because you havent set minimumZoomScale ,which has default value of 1.0 . Since you are trying to set 0.5 which is below the default value, it wouldn't work.
Add following line just after the line which sets maximumZoomScale.
[imageScrollView setMinimumZoomScale:0.25];
As user Rivera pointed out the return value of viewForZoomingInScrollView: was off course not right.
I always returned the current visible page shown in the scrollView. Which means setting the zoom in viewDidAppear doesn't change anything.
Here is the correct code: I made a function which will always resets both images left and right of the current visible scroll page:
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView {
[self updateImageSize];
}
- (void)updateImageSize
{
updatePage = updatePage + 1;
if (updatePage < imagescrolllinkArray.count) {
UIScrollView *changeScrollView = (UIScrollView*)[imagescrolllinkArray objectAtIndex:updatePage];
[changeScrollView setZoomScale:changeScrollView.minimumZoomScale];
}
updatePage = updatePage - 2;
if (updatePage > -1) {
UIScrollView *changeScrollView = (UIScrollView*)[imagescrolllinkArray objectAtIndex:updatePage];
[changeScrollView setZoomScale:changeScrollView.minimumZoomScale];
}
//reset to current view
updatePage = updatePage + 1;
}
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
return [imagelinkArray objectAtIndex:updatePage];
}
and in viewDidAppear I added the following to update the first image before any dragging.
if (i == 1) {
updatePage = 0;
[imageScrollView setZoomScale:imageScrollView.minimumZoomScale];
}
In the meantime I figured out that the code below can under certain circumstances make problems. Sometimes when I zoom in and out from an image the main ScrollView can't be scrolled anymore, so there is no way to get to the next image, except of triggering the pageControl or except of zooming into the image and then scrolling to its borders so the main ScrollView jumps to the next page.
Means the problem only occurs when the image is fully zoomed out (.scale = .minimumscale). I don't understand exactly when and why it happens. Logging viewDidScroll returns nothing in this situations.
Anybody experienced similar problems?
I have a scenario where I need to implement an Offline Map concept for which I am using the image of map on a UIScrollView that zooms on PinchGesture, which works fine.
Problem
I have a UIButton on map. While zooming, the button does not track its position with respect to UIImageView which is being scaled.I am able to reframe the button without affecting its size. But the position is wrong.
TLDR,
I need to reproduce the mapView with annotation kinda concept on UIScrollView with UIImage on it. Can any one help?
Thanks in advance :)
I have found the answer for this. I initially stored the button value in a CGRect initialButtonFrame. Then I updated the button frame (only origins, not the size of the button size as I wanted the button not to zoom like the image ie; I button should not zoom) using the scrollview delegate
- (void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(float)scale
{
[self manageImageOnScrollView];//here i managed the image's coordinates and zoom
[self manageButtonCoordinatesWithRespectToImageWithScale:scale];
}
-(void)manageButtonCoordinatesWithRespectToImageWithScale:(float)scaleFactor
{
//initialButtonFrame is frame of button
self.button.frame = CGRectMake((initialButtonFrame.origin.x * scaleFactor),
(initialButtonFrame.origin.y * scaleFactor),
initialButtonFrame.size.width,
initialButtonFrame.size.height);
[self.scrollView addSubview:self.button];// I removed the button from superview while zooming and later added with updated button coordinates which I got here
}
If you know your current offset and zoom of your map, you should be able to compute the position of your button:
//Assuming your map image has its origin at 0, 0
CGPoint mapOffsetX, mapOffsetY; // these would come from your map as you calculated it.
CGPoint mapZoomFactor; // 1.0 means not zoomed, 3.0 means zooming in 3x, etc
CGPoint buttonAnchorPosition; //the position of your button on your map at 1.0 zoom
CGFloat buttonX = buttonAnchorPosition.x * mapZoomFactor + mapOffsetX;
CGFloat buttonY = buttonAnchorPosition.y * mapZoomFactor + mapOffsetY;
CGPoint buttonPosition = CGPointMake(buttonX, buttonY);
button.position = buttonPosition;
Try that, good luck
I'm trying to get notified when UIScrollView is pinch zoomed out beyond its minimum zoom limit and is about to animate back, but I'm finding it very difficult. Is there a way I can do this with delegate methods alone or do I need to override UIScrollView's touch handling?
Use scrollViewDidZoom: and check if scrollView.zoomBouncing == YES. Then use zoomScale to determine which direction the view is bouncing.
- (void)scrollViewDidZoom:(UIScrollView *)scrollView {
if (scrollView.zoomBouncing) {
if (scrollView.zoomScale == scrollView.maximumZoomScale) {
NSLog(#"Bouncing back from maximum zoom");
}
else
if (scrollView.zoomScale == scrollView.minimumZoomScale) {
NSLog(#"Bouncing back from minimum zoom");
}
}
}
You can use UIScrollView's scrollViewDidZoom delegate method to detect the moment it's about to animate back. You'll see scrollView.zoomScale drop below scrollView.minimumZoomScale while the view is being pinched. Then, as soon as the user releases their fingers, scrollViewDidZoom will be called once again with scrollView.zoomScale == scrollView.minimumZoomScale, but scrollView.zooming == NO.
Capturing this moment is fine and all, but attempting to do anything to preempt the bounce-back-to-minimumZoomScale animation seems to have really odd side effects for me. :(
In Swift 4.0:
func scrollViewDidZoom(_ scrollView: UIScrollView) {
if scrollView.zoomScale == scrollView.minimumZoomScale
{
print("zoomed out")
}
}
This will be called exactly when the user has finished zooming and the zoomScale is at its minimum possible value, i.e. when the scroll view is zoomed out completely.
I did it with UIPinchGestureRecognizer.
-(void)viewDidLoad{
UIPinchGestureRecognizer *gestureRecognizer =
[[[UIPinchGestureRecognizer alloc] initWithTarget:self
action:#selector(pinched:)]
autorelease];
gestureRecognizer.delegate=self;
[self.scrollView addGestureRecognizer:gestureRecognizer];
//your code
}
-(void)pinched:(UIPinchGestureRecognizer*)gestureRecognizer{
if(gestureRecognizer.state==UIGestureRecognizerStateEnded){
//pinch ended
NSLog(#"scale: %f",scrollView.zoomScale);
}
}
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer
shouldRecognizeSimultaneouslyWithGestureRecognizer:
(UIGestureRecognizer *)otherGestureRecognizer{
return YES;
}