直接上代码

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//

//  MoveScaleImageController.h

//  MoveScaleImage

//

//  Created by  on 12-4-24.

//  Copyright (c) 2012年 __MyCompanyName__. All rights reserved.

//

#import

#import "MoveScaleImageView.h"

@interface MoveScaleImageController : UIViewController{

    UIScrollView *myScrollView;

    UIImageView *myImageView;

}

@property(retain,nonatomic)UIScrollView *myScrollView;

@property(retain,nonatomic)UIImageView *myImageView;

@end

//

//  MoveScaleImageController.m

//  MoveScaleImage

//

//  Created by  on 12-4-24.

//  Copyright (c) 2012年 __MyCompanyName__. All rights reserved.

//

#import "MoveScaleImageController.h"

@interface MoveScaleImageController ()

@end

@implementation MoveScaleImageController

@synthesize myScrollView;

@synthesize myImageView;

-(void)dealloc{

    [myScrollView release];

    [myImageView release];

    [super dealloc];

}

-(void)loadView{

    [super loadView];

    self.view.backgroundColor = [UIColor lightGrayColor];

//    UIButton *btn = [UIButton buttonWithType:UIButtonTypeRoundedRect];

    UIButton *btn = [[UIButton alloc]initWithFrame:CGRectMake(110, 200, 100, 50)];

//    [btn setFrame:CGRectMake(110, 200, 100, 40)];

    [btn setBackgroundColor:[UIColor whiteColor]];

    [btn setTitle:@"点击查看图片" forState:UIControlStateNormal];

    [btn.titleLabel setFont:[UIFont systemFontOfSize:13]];

    [btn setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];

    [btn addTarget:self action:@selector(clickEvent:) forControlEvents:UIControlEventTouchUpInside];

    [self.view addSubview:btn];

    [btn release];

    //下面是我要剪切区域的覆盖层

//    if(self.centerOverLayView==nil)

//    {

//        UIView *centerView=[[UIView alloc] initWithFrame:CGRectMake(20, 100, 280, 210)];

//        self.centerOverLayView=centerView;

//        [centerView release];

//    }

//    self.centerOverLayView.backgroundColor=[UIColor clearColor];

//    self.centerOverLayView.layer.borderColor=[UIColor orangeColor].CGColor;

//    self.centerOverLayView.layer.borderWidth=2.0;

//    [self.view addSubview:self.centerOverLayView];

}

-(void)clickEvent:(id)sender{

    NSLog(@"***********clickeventad");

    myScrollView = [[UIScrollView alloc]initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)];

    if(self.myScrollView==nil)

    {

        UIScrollView *scrollView=[[UIScrollView alloc] initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)];

        self.myScrollView=scrollView;

        [scrollView release];

    }

    self.myScrollView.backgroundColor=[UIColor blueColor];

    self.myScrollView.delegate=self;

    self.myScrollView.multipleTouchEnabled=YES;

    self.myScrollView.minimumZoomScale=1.0;

    self.myScrollView.maximumZoomScale=10.0;

    [self.view addSubview:self.myScrollView];

    UIImage *_p_w_picpath = [UIImage p_w_picpathNamed:@"p_w_picpath.jpg"];

    CGFloat p_w_picpathView_X = (_p_w_picpath.size.width > self.view.frame.size.width) ? self.view.frame.size.width : _p_w_picpath.size.width;

    CGFloat p_w_picpathView_Y;

    CGFloat origin;

    if(_p_w_picpath.size.width > self.view.frame.size.width){

        origin = self.view.frame.size.width/_p_w_picpath.size.width;

        p_w_picpathView_Y = _p_w_picpath.size.height*origin;

    }

    myImageView = [[UIImageView alloc]initWithFrame:CGRectMake((self.view.frame.size.width-p_w_picpathView_X)/2, (self.view.frame.size.height-p_w_picpathView_Y)/2, p_w_picpathView_X, p_w_picpathView_Y)];

    if(self.myImageView==nil)

    {

        UIImageView *p_w_picpathView=[[UIImageView alloc] initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)];

        self.myImageView=p_w_picpathView;

        [p_w_picpathView release];

    }

//    [myImageView setImage:_p_w_picpath];

    UIImage *originImage=[[UIImage alloc]initWithCGImage:_p_w_picpath.CGImage];

    [myImageView setImage:originImage];

//    [myImageView setFrame:CGRectMake(0, 0, _p_w_picpath.size.width, _p_w_picpath.size.height)];

    [self.myScrollView addSubview:self.myImageView];

    UIButton *closeBtn = [[UIButton alloc]initWithFrame:CGRectMake(10, 10, 50, 50)];

    [closeBtn setBackgroundColor:[UIColor redColor]];

    [closeBtn setAlpha:0.5];

    [closeBtn addTarget:self action:@selector(closeEvent:) forControlEvents:UIControlEventTouchUpInside];

    [self.view addSubview:closeBtn];

    [closeBtn release];

//    UIView *backView = [[UIView alloc] initWithFrame:CGRectInset(self.view.frame, 5, 5)];

//    backView.alpha = 0.5;

//    backView.backgroundColor = [UIColor blackColor];

////    [self.view addSubview:backView];

//

//    UIImage* p_w_picpath=[UIImage p_w_picpathNamed:@"p_w_picpath.jpg"];

//    MoveScaleImageView*fileContent = [[MoveScaleImageView alloc]initWithFrame:CGRectMake(0, 44, 320, 436)];

//    [fileContent setImage:p_w_picpath];

//

////    [backView addSubview:fileContent];

//    [self.view addSubview:fileContent];

//

//    [backView release];

//    [fileContent release];

}

-(void)closeEvent:(id)sender{

    [self.myImageView setHidden:YES];

    [self.myScrollView setHidden:YES];

}

#pragma mark UIScrollView delegate methods

//实现图片的缩放

-(UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView{

    NSLog(@"**************viewForZoomingInScrollView");

    return self.myImageView;

}

//实现图片在缩放过程中居中

- (void)scrollViewDidZoom:(UIScrollView *)scrollView

{

    CGFloat offsetX = (scrollView.bounds.size.width > scrollView.contentSize.width)?(scrollView.bounds.size.width - scrollView.contentSize.width)/2 : 0.0;

    CGFloat offsetY = (scrollView.bounds.size.height > scrollView.contentSize.height)?(scrollView.bounds.size.height - scrollView.contentSize.height)/2 : 0.0;

    self.myImageView.center = CGPointMake(scrollView.contentSize.width/2 + offsetX,scrollView.contentSize.height/2 + offsetY);

}

- (void)viewDidLoad

{

    [super viewDidLoad];

// Do any additional setup after loading the view.

}

- (void)viewDidUnload

{

    [super viewDidUnload];

    // Release any retained subviews of the main view.

}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation

{

    return (interfaceOrientation == UIInterfaceOrientationPortrait);

}

@end

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文章题目：iOS实现图片的缩放和居中显示-创新互联
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