/*

     File: APLViewController.m

 Abstract: The main view controller for this application. The gesture recognizers for the view's pieces are set up in the storyboard.

  Version: 2.0

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 */

#import "APLViewController.h"

#import <QuartzCore/QuartzCore.h>

@interface APLViewController ()

// Views the user can move.

@property (nonatomic, weak) IBOutlet UIImageView *firstPieceView;

@property (nonatomic, weak) IBOutlet UIImageView *secondPieceView;

@property (nonatomic, weak) IBOutlet UIImageView *thirdPieceView;

@property (nonatomic, weak) UIView *pieceForReset;

@end

@implementation APLViewController

#pragma mark - Utility methods

/**

 Scale and rotation transforms are applied relative to the layer's anchor point this method moves a gesture recognizer's view's anchor point between the user's fingers.

 */

- (void)adjustAnchorPointForGestureRecognizer:(UIGestureRecognizer *)gestureRecognizer

{

    if (gestureRecognizer.state == UIGestureRecognizerStateBegan) {

        UIView *piece = gestureRecognizer.view;

        CGPoint locationInView = [gestureRecognizer locationInView:piece];

        CGPoint locationInSuperview = [gestureRecognizer locationInView:piece.superview];

        piece.layer.anchorPoint = CGPointMake(locationInView.x / piece.bounds.size.width, locationInView.y / piece.bounds.size.height);

        piece.center = locationInSuperview;

    }

}

/**

 Display a menu with a single item to allow the piece's transform to be reset.

 */

- (IBAction

   )showResetMenu:(UILongPressGestureRecognizer *)gestureRecognizer

{

    if ([gestureRecognizer state] == UIGestureRecognizerStateBegan) {

        [self becomeFirstResponder];

        self.pieceForReset = [gestureRecognizer view];

        /*

         Set up the reset menu.

         */

        NSString *menuItemTitle = NSLocalizedString(@"Reset", @"Reset menu item title");

        UIMenuItem *resetMenuItem = [[UIMenuItem alloc] initWithTitle:menuItemTitle action:@selector(resetPiece:)];

        UIMenuController *menuController = [UIMenuController sharedMenuController];

        [menuController setMenuItems:@[resetMenuItem]];

        CGPoint location = [gestureRecognizer locationInView:[gestureRecognizer view]];

        CGRect menuLocation = CGRectMake(location.x, location.y, 0, 0);

        [menuController setTargetRect:menuLocation inView:[gestureRecognizer view]];

        [menuController setMenuVisible:YES animated:YES];

    }

}

/**

 Animate back to the default anchor point and transform.

 */

- (void)resetPiece:(UIMenuController *)controller

{

    UIView *pieceForReset = self.pieceForReset;

    CGPoint centerPoint = CGPointMake(CGRectGetMidX(pieceForReset.bounds), CGRectGetMidY(pieceForReset.bounds));

    CGPoint locationInSuperview = [pieceForReset convertPoint:centerPoint toView:[pieceForReset superview]];

    [[pieceForReset layer] setAnchorPoint:CGPointMake(0.5, 0.5)];

    [pieceForReset setCenter:locationInSuperview];

    [UIView beginAnimations:nil context:nil];

    [pieceForReset setTransform:CGAffineTransformIdentity];

    [UIView commitAnimations];

}

// UIMenuController requires that we can become first responder or it won't display

- (BOOL)canBecomeFirstResponder

{

    return YES;

}

#pragma mark - Touch handling

/**

 Shift the piece's center by the pan amount.

 Reset the gesture recognizer's translation to {0, 0} after applying so the next callback is a delta from the current position.

 */

- (IBAction)panPiece:(UIPanGestureRecognizer *)gestureRecognizer

{

    UIView *piece = [gestureRecognizer view];

    [self adjustAnchorPointForGestureRecognizer:gestureRecognizer];

    if ([gestureRecognizer state] == UIGestureRecognizerStateBegan || [gestureRecognizer state] == UIGestureRecognizerStateChanged) {

        CGPoint translation = [gestureRecognizer translationInView:[piece superview]];

        [piece setCenter:CGPointMake([piece center].x + translation.x, [piece center].y + translation.y)];

        [gestureRecognizer setTranslation:CGPointZero inView:[piece superview]];

    }

}

/**

 Rotate the piece by the current rotation.

 Reset the gesture recognizer's rotation to 0 after applying so the next callback is a delta from the current rotation.

 */

- (IBAction)rotatePiece:(UIRotationGestureRecognizer *)gestureRecognizer

{

    [self adjustAnchorPointForGestureRecognizer:gestureRecognizer];

    if ([gestureRecognizer state] == UIGestureRecognizerStateBegan || [gestureRecognizer state] == UIGestureRecognizerStateChanged) {

        [gestureRecognizer view].transform = CGAffineTransformRotate([[gestureRecognizer view] transform], [gestureRecognizer rotation]);

        [gestureRecognizer setRotation:0];

    }

}

/**

 Scale the piece by the current scale.

 Reset the gesture recognizer's rotation to 0 after applying so the next callback is a delta from the current scale.

 */

- (IBAction)scalePiece:(UIPinchGestureRecognizer *)gestureRecognizer

{

    [self adjustAnchorPointForGestureRecognizer:gestureRecognizer];

    if ([gestureRecognizer state] == UIGestureRecognizerStateBegan || [gestureRecognizer state] == UIGestureRecognizerStateChanged) {

        [gestureRecognizer view].transform = CGAffineTransformScale([[gestureRecognizer view] transform], [gestureRecognizer scale], [gestureRecognizer scale]);

        [gestureRecognizer setScale:1];

    }

}

/**

 Ensure that the pinch, pan and rotate gesture recognizers on a particular view can all recognize simultaneously.

 Prevent other gesture recognizers from recognizing simultaneously.

 */

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer

{

    // If the gesture recognizers's view isn't one of our pieces, don't allow simultaneous recognition.

    if (gestureRecognizer.view != self.firstPieceView && gestureRecognizer.view != self.secondPieceView && gestureRecognizer.view != self.thirdPieceView) {

        return NO;

    }

    // If the gesture recognizers are on different views, don't allow simultaneous recognition.

    if (gestureRecognizer.view != otherGestureRecognizer.view) {

        return NO;

    }

    // If either of the gesture recognizers is the long press, don't allow simultaneous recognition.

    if ([gestureRecognizer isKindOfClass:[UILongPressGestureRecognizer class]] || [otherGestureRecognizer isKindOfClass:[UILongPressGestureRecognizer class]]) {

        return NO;

    }

    return YES;

}

@end