放大镜效果
MagnifierView.h文件：
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#import <Foundation/Foundation.h>@interface MagnifierView : UIView {UIView *viewref;CGPoint touchPoint;UIImage *cachedImage;}@property(nonatomic, retain) UIView *viewref;@property(assign) CGPoint touchPoint;@end?
MagnifierView.m文件：
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#import "MagnifierView.h"@implementation MagnifierView@synthesize viewref, touchPoint;- (id)initWithFrame:(CGRect)frame {if (self = [super initWithFrame:frame]) {self.backgroundColor = [UIColor clearColor];}return self;}- (void)drawRect:(CGRect)rect {if(cachedImage == nil){UIGraphicsBeginImageContext(self.bounds.size);[self.viewref.layer renderInContext:UIGraphicsGetCurrentContext()];cachedImage = [UIGraphicsGetImageFromCurrentImageContext() retain];UIGraphicsEndImageContext();}CGImageRef imageRef = [cachedImage CGImage];CGImageRef maskRef = [[UIImage imageNamed:@"loopmask.png"] CGImage];CGImageRef overlay = [[UIImage imageNamed:@"loop.png"] CGImage];CGImageRef mask = CGImageMaskCreate(CGImageGetWidth(maskRef), CGImageGetHeight(maskRef),CGImageGetBitsPerComponent(maskRef), CGImageGetBitsPerPixel(maskRef),CGImageGetBytesPerRow(maskRef), CGImageGetDataProvider(maskRef), NULL, true);CGImageRef subImage = CGImageCreateWithImageInRect(imageRef, CGRectMake(touchPoint.x - 18, touchPoint.y - 18, 36, 36));CGImageRef xMaskedImage = CGImageCreateWithMask(subImage, mask);CGContextRef context = UIGraphicsGetCurrentContext();CGAffineTransform xform = CGAffineTransformMake(1.0, 0.0, 0.0, -1.0, 0.0, 0.0);CGContextConcatCTM(context, xform);CGRect area = CGRectMake(touchPoint.x - 42, -touchPoint.y, 85, 85);CGRect area2 = CGRectMake(touchPoint.x - 40, -touchPoint.y + 2, 80, 80);CGContextDrawImage(context, area2, xMaskedImage);CGContextDrawImage(context, area, overlay);}- (void)dealloc {[cachedImage release];[viewref release];[super dealloc];}@end?
TouchReader.h文件：
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#import <Foundation/Foundation.h>#import "MagnifierView.h"@interface TouchReader : UIView {NSTimer *touchTimer;MagnifierView *loop;}- (void) handleAction:(id)timerObj;@end?
TouchReader.m文件：
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#import "TouchReader.h"#import "MagnifierView.h"@implementation TouchReader- (id)initWithFrame:(CGRect)frame {if (self = [super initWithFrame:frame]) {touchTimer = nil;loop = nil;}return self;}- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{touchTimer = [NSTimer scheduledTimerWithTimeInterval:1.0target:selfselector:@selector(handleAction:)userInfo:touches repeats:NO];}- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{if(loop != nil){[self handleAction:touches];return;}[touchTimer invalidate];touchTimer = [NSTimer scheduledTimerWithTimeInterval:1.0target:selfselector:@selector(handleAction:)userInfo:touches repeats:NO];}- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event{[touchTimer invalidate];touchTimer = nil;[loop removeFromSuperview];[loop release];loop = nil;}- (void) handleAction:(id)timerObj {NSSet *touches;if([timerObj isKindOfClass:[NSSet class]]){touches = [timerObj retain];}else{touches = [[timerObj userInfo] retain];}if(touchTimer != nil){[touchTimer invalidate];touchTimer = nil;}if(loop == nil){loop = [[MagnifierView alloc] initWithFrame:self.bounds];loop.viewref = self;[self addSubview:loop];}UITouch *touch = [touches anyObject];loop.touchPoint = [touch locationInView:self];[loop setNeedsDisplay];[touches release];}- (void)dealloc {[super dealloc];}@end?
示例图：
