how to double tap zoom and two fingure zoom uiimage in uiscrollview - iphone

Question

hi i have actually multiple images in uiscrollview. actually i want to implement image scrolling like in iphone image gallary. am downloading images from url to imagearray then i can successfully display and scroll these images from imagearray in uiscrollview. but my problem is i want to enable double tap zoom in/out and two fingure zoom in/out in uiscrollviiew like in iphone gallary . like when user double tap an image will zoom in . and when user again double tap that image that image will zoom . and also same case with twofingur gesture. i tried to implement it reading tutorials but cant succeeded actually the problem is when i double tap an image doubletap image method called succcessfully but can do effect on image size this is the code which i have been implement for scrolling and gesture recognition
for gesture recognition i used the code one from the apple site
if (imagesArray.count < 1)
{
msgView = [[UIView alloc]initWithFrame:CGRectMake(35, 190, 250, 40)];
[msgView setBackgroundColor:[UIColor blackColor]];
[msgView setAlpha:0.5];
UILabel *mgtLbl = [[UILabel alloc]initWithFrame:CGRectMake(25, 8, 250, 25)];
[mgtLbl setText:#"Sorry no image available for this post"];
[mgtLbl setFont:[UIFont systemFontOfSize:13.0]];
[mgtLbl setBackgroundColor:[UIColor clearColor]];
[mgtLbl setTextColor:[UIColor blueColor]];
[msgView addSubview:mgtLbl];
[self.view addSubview:msgView];
}
else {
[msgView removeFromSuperview];
[self.view setBackgroundColor:[UIColor blackColor]];
srcVw = [[UIScrollView alloc]initWithFrame:CGRectMake(0, 0, 320, 480)];
srcVw.scrollEnabled = YES;
srcVw.delegate = self;
[srcVw setZoomScale:1.0];
srcVw.showsHorizontalScrollIndicator = YES;
srcVw.showsVerticalScrollIndicator = NO;
srcVw.pagingEnabled = NO;
//add the scrollview to the view
srcVw = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0,self.view.frame.size.width,self.view.frame.size.height)];
srcVw.pagingEnabled = YES;
[srcVw setAlwaysBounceVertical:NO];
//setup internal views
NSInteger numberOfViews = imagesArray.count;
for (int i = 0; i < numberOfViews; i++) {
CGFloat xOrigin = i * self.view.frame.size.width;
image = [[UIImageView alloc] initWithFrame:CGRectMake(xOrigin, 0,self.view.frame.size.width,400)];
/*
[image setImageWithURL:[NSURL URLWithString:[NSString stringWithFormat: #"http://www.junkremoval.co.uk/bedspace/%#",[imagesArray objectAtIndex:i]]]];
*/
image.image = [imagesArray objectAtIndex:i];
image.contentMode = UIViewContentModeScaleAspectFit;
// image.frame = (CGRect){.origin=CGPointMake(0.0f, 0.0f), .size=image.image.size};
[srcVw addSubview:image];
}
//set the scroll view content size
srcVw.contentSize = CGSizeMake(self.view.frame.size.width *numberOfViews,
self.view.frame.size.height);
[self.view addSubview:srcVw];
[image setTag:ZOOM_VIEW_TAG];
[image setUserInteractionEnabled:YES];
// add gesture recognizers to the image view
UITapGestureRecognizer *singleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(handleSingleTap:)];
UITapGestureRecognizer *doubleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(handleDoubleTap:)];
UITapGestureRecognizer *twoFingerTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(handleTwoFingerTap:)];
[doubleTap setNumberOfTapsRequired:2];
[twoFingerTap setNumberOfTouchesRequired:2];
[image addGestureRecognizer:singleTap];
[image addGestureRecognizer:doubleTap];
[image addGestureRecognizer:twoFingerTap];
// calculate minimum scale to perfectly fit image width, and begin at that scale
float minimumScale = [srcVw frame].size.width / [image frame].size.width;
[srcVw setMinimumZoomScale:minimumScale];
[srcVw setZoomScale:minimumScale];
}
/************************************** NOTE **************************************/
/* The following delegate method works around a known bug in zoomToRect:animated: */
/* In the next release after 3.0 this workaround will no longer be necessary */
/**********************************************************************************/
- (void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(float)scale {
[scrollView setZoomScale:scale+0.01 animated:NO];
[scrollView setZoomScale:scale animated:NO];
}
#pragma mark TapDetectingImageViewDelegate methods
- (void)handleSingleTap:(UIGestureRecognizer *)gestureRecognizer {
// single tap does nothing for now
}
- (void)handleDoubleTap:(UIGestureRecognizer *)gestureRecognizer {
// double tap zooms in
float newScale = [srcVw zoomScale] * ZOOM_STEP;
CGRect zoomRect = [self zoomRectForScale:newScale withCenter:[gestureRecognizer locationInView:gestureRecognizer.view]];
[srcVw zoomToRect:zoomRect animated:YES];
}
- (void)handleTwoFingerTap:(UIGestureRecognizer *)gestureRecognizer {
// two-finger tap zooms out
float newScale = [srcVw zoomScale] / ZOOM_STEP;
CGRect zoomRect = [self zoomRectForScale:newScale withCenter:[gestureRecognizer locationInView:gestureRecognizer.view]];
[srcVw zoomToRect:zoomRect animated:YES];
}
#pragma mark Utility methods
- (CGRect)zoomRectForScale:(float)scale withCenter:(CGPoint)center {
CGRect zoomRect;
// the zoom rect is in the content view's coordinates.
// At a zoom scale of 1.0, it would be the size of the imageScrollView's bounds.
// As the zoom scale decreases, so more content is visible, the size of the rect grows.
zoomRect.size.height = [srcVw frame].size.height / scale;
zoomRect.size.width = [srcVw frame].size.width / scale;
// choose an origin so as to get the right center.
zoomRect.origin.x = center.x - (zoomRect.size.width / 2.0);
zoomRect.origin.y = center.y - (zoomRect.size.height / 2.0);
return zoomRect;
}

Answer 1

I guess you have all you need here