iphone – 如何将放大镜添加到自定义控件？

1.将以下文件添加到项目中：

@H_265_5@magnifierView.h：

//
//  MagnifierView.h
//  SimplerMaskTest
//

#import <UIKit/UIKit.h>

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

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

@end

@H_265_5@magnifierView.m：

//
//  MagnifierView.m
//  SimplerMaskTest
//

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

@implementation MagnifierView
@synthesize viewToMagnify;
@dynamic touchPoint;

- (id)initWithFrame:(CGRect)frame {
    return [self initWithFrame:frame radius:118];
}

- (id)initWithFrame:(CGRect)frame radius:(int)r {
    int radius = r;

    if ((self = [super initWithFrame:CGRectMake(0,radius,radius)])) {
        //Make the layer circular.
        self.layer.cornerRadius = radius / 2;
        self.layer.masksToBounds = YES;
    }

    return self;
}

- (void)setTouchPoint:(CGPoint)pt {
    touchPoint = pt;
    // whenever touchPoint is set,update the position of the magnifier (to just above what's being magnified)
    self.center = CGPointMake(pt.x,pt.y-66);
}

- (CGPoint)getTouchPoint {
    return touchPoint;
}

- (void)drawRect:(CGRect)rect {
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGRect bounds = self.bounds;
    CGImageRef mask = [UIImage imagenamed: @"loupe-mask@2x.png"].CGImage;
    UIImage *glass = [UIImage imagenamed: @"loupe-hi@2x.png"];

    CGContextSaveGState(context);
    CGContextClipToMask(context,bounds,mask);
    CGContextFillRect(context,bounds);
    CGContextScaleCTM(context,1.2,1.2);

    //draw your subject view here
    CGContextTranslateCTM(context,1*(self.frame.size.width*0.5),1*(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];

    CGContextRestoreGState(context);
    [glass drawInRect: bounds];
}

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


@end

TouchReader.h：

//
//  TouchReader.h
//  SimplerMaskTest
//

#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：

//
//  TouchReader.m
//  SimplerMaskTest
//

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

@implementation TouchReader

@synthesize touchTimer;

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
    self.touchTimer = [NSTimer scheduledTimerWithTimeInterval:0.5 target:self SELEctor:@SELEctor(addLoop) userInfo:nil repeats:NO];

    // just create one loop and re-use it.
    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 removeFromSuperview];
}

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

- (void)addLoop {
    // add the loop to the superview.  if we add it to the view it magnifies,it'll magnify itself!
    [self.superview addSubview:loop];
    // here,we Could do some nice animation instead of just adding the subview...
}

- (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

基于：http://coffeeshopped.com/2010/03/a-simpler-magnifying-glass-loupe-view-for-the-iphone

2.添加以下图像：

代码上使用的图像：

loupe-hi@2x.png：

loupe-mask@2x.png：

带阴影的原始但居中的图像(此时不使用)：

loupe-shadow-hi@2x.png：

loupe-shadow-mask@2x.png：

3.用TouchReader替换xib文件中的主UIView

放大镜将自动工作,除了捕获自己的触摸事件的控件(例如,UIWebView).上面的代码不支持带阴影的图像.如果您成功解决了此问题,请为qustion添加新答案.

更新：

更改以下代码以添加UIWebView支持. UIView应该保持UIView.

@interface TouchReader : UILongPressGestureRecognizer

并向webView添加手势：

TouchReader* gestureMagnifier = [[[TouchReader alloc] initWithTarget:self action:@SELEctor(handleMagnifier:)] autorelease];
gestureMagnifier.webView = editsource;
gestureMagnifier.delegate = self;
gestureMagnifier.minimumPressDuration = 0.5;
[webView addGestureRecognizer:gestureMagnifier];