Retired Document
Important: This sample code may not represent best practices for current development. The project may use deprecated symbols and illustrate technologies and techniques that are no longer recommended.
3_Tiling/Classes/ThumbImageView.m
/* |
File: ThumbImageView.m |
Abstract: UIImageView subclass to display a thumbnail image; notifies a delegate of various interactions. |
Version: 1.1 |
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*/ |
/************************************** NOTE **************************************/ |
/* For detailed comments on the ThumbImageView class, please see the Autoscroll */ |
/* project in this sample code suite. */ |
/**********************************************************************************/ |
#import "ThumbImageView.h" |
#define DRAG_THRESHOLD 10 |
float distanceBetweenPoints(CGPoint a, CGPoint b); |
@implementation ThumbImageView |
@synthesize delegate; |
@synthesize imageName; |
@synthesize imageSize; |
@synthesize home; |
@synthesize touchLocation; |
- (id)initWithImage:(UIImage *)image { |
self = [super initWithImage:image]; |
if (self) { |
[self setUserInteractionEnabled:YES]; |
[self setExclusiveTouch:YES]; |
} |
return self; |
} |
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { |
// store the location of the starting touch so we can decide when we've moved far enough to drag |
touchLocation = [[touches anyObject] locationInView:self]; |
if ([delegate respondsToSelector:@selector(thumbImageViewStartedTracking:)]) |
[delegate thumbImageViewStartedTracking:self]; |
} |
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event { |
// we want to establish a minimum distance that the touch has to move before it counts as dragging, |
// so that the slight movement involved in a tap doesn't cause the frame to move. |
CGPoint newTouchLocation = [[touches anyObject] locationInView:self]; |
if (dragging) { |
float deltaX = newTouchLocation.x - touchLocation.x; |
float deltaY = newTouchLocation.y - touchLocation.y; |
[self moveByOffset:CGPointMake(deltaX, deltaY)]; |
} |
else if (distanceBetweenPoints(touchLocation, newTouchLocation) > DRAG_THRESHOLD) { |
touchLocation = newTouchLocation; |
dragging = YES; |
} |
} |
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event { |
if (dragging) { |
[self goHome]; |
dragging = NO; |
} else if ([[touches anyObject] tapCount] == 1) { |
if ([delegate respondsToSelector:@selector(thumbImageViewWasTapped:)]) |
[delegate thumbImageViewWasTapped:self]; |
} |
if ([delegate respondsToSelector:@selector(thumbImageViewStoppedTracking:)]) |
[delegate thumbImageViewStoppedTracking:self]; |
} |
- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event { |
[self goHome]; |
dragging = NO; |
if ([delegate respondsToSelector:@selector(thumbImageViewStoppedTracking:)]) |
[delegate thumbImageViewStoppedTracking:self]; |
} |
- (void)goHome { |
float distanceFromHome = distanceBetweenPoints([self frame].origin, [self home].origin); // distance is in pixels |
float animationDuration = 0.1 + distanceFromHome * 0.001; |
[UIView beginAnimations:nil context:NULL]; |
[UIView setAnimationDuration:animationDuration]; |
[self setFrame:[self home]]; |
[UIView commitAnimations]; |
} |
- (void)moveByOffset:(CGPoint)offset { |
CGRect frame = [self frame]; |
frame.origin.x += offset.x; |
frame.origin.y += offset.y; |
[self setFrame:frame]; |
if ([delegate respondsToSelector:@selector(thumbImageViewMoved:)]) |
[delegate thumbImageViewMoved:self]; |
} |
@end |
float distanceBetweenPoints(CGPoint a, CGPoint b) { |
float deltaX = a.x - b.x; |
float deltaY = a.y - b.y; |
return sqrtf( (deltaX * deltaX) + (deltaY * deltaY) ); |
} |
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