放大镜效果（二）

以前也写过一篇：放大镜效果，现在，提供另一种解决方案。

 

MagnifierView.h

 

@interface MagnifierView : UIWindow {
	UIView *viewToMagnify;
	CGPoint touchPoint;
}

@property (nonatomic, retain) UIView *viewToMagnify;
@property (assign) CGPoint touchPoint;

@end

 

MagnifierView.m

 

#import "MagnifierView.h"
#import <QuartzCore/QuartzCore.h>

@implementation MagnifierView
@synthesize viewToMagnify, touchPoint;

- (id)initWithFrame:(CGRect)frame {
	if (self = [super initWithFrame:CGRectMake(0, 0, 80, 80)]) {
		self.layer.borderColor = [[UIColor lightGrayColor] CGColor];
		self.layer.borderWidth = 3;
		self.layer.cornerRadius = 40;
		self.layer.masksToBounds = YES;
		self.windowLevel = UIWindowLevelAlert;
	}
	return self;
}

- (void)setTouchPoint:(CGPoint)pt {
	touchPoint = pt;
	self.center = CGPointMake(pt.x, pt.y-10);
}

- (void)drawRect:(CGRect)rect {
	CGContextRef context = UIGraphicsGetCurrentContext();
	CGContextTranslateCTM(context, self.frame.size.width * 0.5, self.frame.size.height * 0.5);
	CGContextScaleCTM(context, 1.5, 1.5);
	CGContextTranslateCTM(context, -1 * (touchPoint.x), -1 * (touchPoint.y));
	[self.viewToMagnify.layer renderInContext:context];
}

- (void)dealloc {
	[viewToMagnify release];
	[super dealloc];
}

@end

 

TouchReader.h

 

#import <UIKit/UIKit.h>
#import "MagnifierView.h"

@interface TouchReader : UIView {
	NSTimer *touchTimer;
	MagnifierView *loop;
}

@property (nonatomic, retain) NSTimer *touchTimer;

- (void)addLoop;
- (void)handleAction:(id)timerObj;

@end

 

TouchReader.m

 

#import "TouchReader.h"
#import "MagnifierView.h"

@implementation TouchReader

@synthesize touchTimer;

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
	self.clipsToBounds = NO;
	self.touchTimer = [NSTimer scheduledTimerWithTimeInterval:0.5
													   target:self
													 selector:@selector(addLoop)
													 userInfo:nil
													  repeats:NO];
	if(loop == nil){
		loop = [[MagnifierView alloc] init];
		loop.viewToMagnify = self;
	}
	
	UITouch *touch = [touches anyObject];
	loop.touchPoint = [touch locationInView:self];
	[loop setNeedsDisplay];
}

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
	[self handleAction:touches];
}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
	[self.touchTimer invalidate];
	self.touchTimer = nil;
	[loop release];
	loop = nil;
}

- (void)addLoop {
	[loop makeKeyAndVisible];
}

- (void)handleAction:(id)timerObj {
	NSSet *touches = timerObj;
	UITouch *touch = [touches anyObject];
	loop.touchPoint = [touch locationInView:self];
	[loop setNeedsDisplay];
}

- (void)dealloc {
	[loop release];
	loop = nil;
	[super dealloc];
}

@end