On my first attempt made a mistake in trying to mask a UIImage instead of a UIImage view, but eventually got a pretty decent working solution (which uses a UIImageView mask) below. If you have questions feel free to ask.
I basically create the current image and the filtered image. I mask the UIView (with a rectangle) and then adjust the mask based on the swipe.
Link to result: https://www.youtube.com/watch?v=k75nqVsPggY&list=UUIctdpq1Pzujc0u0ixMSeVw
Mask credit: https://mcmap.net/q/121601/-simply-mask-a-uiview-with-a-rectangle
@interface FilterTestsViewController ()
@end
@implementation FilterTestsViewController
NSArray *_pictureFilters;
NSNumber* _pictureFilterIterator;
UIImage* _originalImage;
UIImage* _currentImage;
UIImage* _filterImage;
UIImageView* _uiImageViewCurrentImage;
UIImageView* _uiImageViewNewlyFilteredImage;
CGPoint _startLocation;
BOOL _directionAssigned = NO;
enum direction {LEFT,RIGHT};
enum direction _direction;
BOOL _reassignIncomingImage = YES;
- (void)viewDidLoad
{
[super viewDidLoad];
[self initializeFiltering];
}
//set it up for video feed
-(void)initializeVideoFeed
{
}
-(void)initializeFiltering
{
//create filters
_pictureFilters = @[@"CISepiaTone",@"CIColorInvert",@"CIColorCube",@"CIFalseColor",@"CIPhotoEffectNoir"];
_pictureFilterIterator = 0;
//create initial image and current image
_originalImage = [UIImage imageNamed:@"ja.jpg"]; //creates image from file, this will result in a nil CIImage but a valid CGImage;
_currentImage = [UIImage imageNamed:@"ja.jpg"];
//create the UIImageViews for the current and filter object
_uiImageViewCurrentImage = [[UIImageView alloc] initWithImage:_currentImage]; //creates a UIImageView with the UIImage
_uiImageViewNewlyFilteredImage = [[UIImageView alloc] initWithFrame:CGRectMake(0,0,[UIScreen mainScreen].bounds.size.width,[UIScreen mainScreen].bounds.size.height)];//need to set its size to full since it doesn't have a filter yet
//add UIImageViews to view
[self.view addSubview:_uiImageViewCurrentImage]; //adds the UIImageView to view;
[self.view addSubview:_uiImageViewNewlyFilteredImage];
//add gesture
UIPanGestureRecognizer* pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(swipeRecognized:)];
[self.view addGestureRecognizer:pan];
}
-(void)swipeRecognized:(UIPanGestureRecognizer *)swipe
{
CGFloat distance = 0;
CGPoint stopLocation;
if (swipe.state == UIGestureRecognizerStateBegan)
{
_directionAssigned = NO;
_startLocation = [swipe locationInView:self.view];
}else
{
stopLocation = [swipe locationInView:self.view];
CGFloat dx = stopLocation.x - _startLocation.x;
CGFloat dy = stopLocation.y - _startLocation.y;
distance = sqrt(dx*dx + dy*dy);
}
if(swipe.state == UIGestureRecognizerStateEnded)
{
if(_direction == LEFT && (([UIScreen mainScreen].bounds.size.width - _startLocation.x) + distance) > [UIScreen mainScreen].bounds.size.width/2)
{
[self reassignCurrentImage];
}else if(_direction == RIGHT && _startLocation.x + distance > [UIScreen mainScreen].bounds.size.width/2)
{
[self reassignCurrentImage];
}else
{
//since no filter applied roll it back
if(_direction == LEFT)
{
_pictureFilterIterator = [NSNumber numberWithInt:[_pictureFilterIterator intValue]-1];
}else
{
_pictureFilterIterator = [NSNumber numberWithInt:[_pictureFilterIterator intValue]+1];
}
}
[self clearIncomingImage];
_reassignIncomingImage = YES;
return;
}
CGPoint velocity = [swipe velocityInView:self.view];
if(velocity.x > 0)//right
{
if(!_directionAssigned)
{
_directionAssigned = YES;
_direction = RIGHT;
}
if(_reassignIncomingImage && !_filterImage)
{
_reassignIncomingImage = false;
[self reassignIncomingImageLeft:NO];
}
}
else//left
{
if(!_directionAssigned)
{
_directionAssigned = YES;
_direction = LEFT;
}
if(_reassignIncomingImage && !_filterImage)
{
_reassignIncomingImage = false;
[self reassignIncomingImageLeft:YES];
}
}
if(_direction == LEFT)
{
if(stopLocation.x > _startLocation.x -5) //adjust to avoid snapping
{
distance = -distance;
}
}else
{
if(stopLocation.x < _startLocation.x +5) //adjust to avoid snapping
{
distance = -distance;
}
}
[self slideIncomingImageDistance:distance];
}
-(void)slideIncomingImageDistance:(float)distance
{
CGRect incomingImageCrop;
if(_direction == LEFT) //start on the right side
{
incomingImageCrop = CGRectMake(_startLocation.x - distance,0, [UIScreen mainScreen].bounds.size.width - _startLocation.x + distance, [UIScreen mainScreen].bounds.size.height);
}else//start on the left side
{
incomingImageCrop = CGRectMake(0,0, _startLocation.x + distance, [UIScreen mainScreen].bounds.size.height);
}
[self applyMask:incomingImageCrop];
}
-(void)reassignCurrentImage
{
if(!_filterImage)//if you go fast this is null sometimes
{
[self reassignIncomingImageLeft:YES];
}
_uiImageViewCurrentImage.image = _filterImage;
self.view.frame = [[UIScreen mainScreen] bounds];
}
//left is forward right is back
-(void)reassignIncomingImageLeft:(BOOL)left
{
if(left == YES)
{
_pictureFilterIterator = [NSNumber numberWithInt:[_pictureFilterIterator intValue]+1];
}else
{
_pictureFilterIterator = [NSNumber numberWithInt:[_pictureFilterIterator intValue]-1];
}
NSNumber* arrayCount = [NSNumber numberWithInt:(int)_pictureFilters.count];
if([_pictureFilterIterator integerValue]>=[arrayCount integerValue])
{
_pictureFilterIterator = 0;
}
if([_pictureFilterIterator integerValue]< 0)
{
_pictureFilterIterator = [NSNumber numberWithInt:(int)_pictureFilters.count-1];
}
CIImage* ciImage = [CIImage imageWithCGImage:_originalImage.CGImage];
CIFilter* filter = [CIFilter filterWithName:_pictureFilters[[_pictureFilterIterator integerValue]] keysAndValues:kCIInputImageKey,ciImage, nil];
_filterImage = [UIImage imageWithCIImage:[filter outputImage]];
_uiImageViewNewlyFilteredImage.image = _filterImage;
CGRect maskRect = CGRectMake(0,0,[UIScreen mainScreen].bounds.size.width,[UIScreen mainScreen].bounds.size.height);
[self applyMask:maskRect];
}
//apply mask to filter UIImageView
-(void)applyMask:(CGRect)maskRect
{
// Create a mask layer and the frame to determine what will be visible in the view.
CAShapeLayer *maskLayer = [[CAShapeLayer alloc] init];
// Create a path with the rectangle in it.
CGPathRef path = CGPathCreateWithRect(maskRect, NULL);
// Set the path to the mask layer.
maskLayer.path = path;
// Release the path since it's not covered by ARC.
CGPathRelease(path);
// Set the mask of the view.
_uiImageViewNewlyFilteredImage.layer.mask = maskLayer;
}
-(void)clearIncomingImage
{
_filterImage = nil;
_uiImageViewNewlyFilteredImage.image = nil;
//mask current image view fully again
[self applyMask:CGRectMake(0,0,[UIScreen mainScreen].bounds.size.width,[UIScreen mainScreen].bounds.size.height)];
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
@end
UIViewContentModeLeft/UIViewContentModeRightseems like it should work. Can you post the code for what you tried to do? You'll need your image sizes to match the actual size of your UIImageViews btw, becauseUIViewContentModeLeftdoes not do any scaling. You'll also need the UIImageView to haveclipsToBounds = YES(just a few things that might go wrong off the top of my head). – Superinduce