[IPhone] 如何将制作图片放大缩小的动作

在IPhone SDK开发范例大全中,有很多的范例码

下面这段范例码,示范了两张图片的交换,以及放大缩小的动画

动画效果请参照下图



[cpp] view
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#import <UIKit/UIKit.h>

#define IMAGE_VIEW_1 100

#define IMAGE_VIEW_2 101

#define BIGRECT CGRectMake(0.0f, 0.0f, 320.0f, 435.0f)

#define SMALLRECT CGRectMake(130.0f, 187.0f, 60.0f, 60.0f)

@interface ToggleView: UIView

{

BOOL isOne;

}

@end

@implementation ToggleView

- (id) initWithFrame: (CGRect) aFrame;

{

self = [super initWithFrame:aFrame];

// Load both views, make them non-interactive

UIImageView *imgView1 = [[UIImageView alloc] initWithFrame:BIGRECT];

imgView1.image = [UIImage imageNamed:@"one.png"];

imgView1.userInteractionEnabled = NO;

imgView1.tag = IMAGE_VIEW_1;

UIImageView *imgView2 = [[UIImageView alloc] initWithFrame:SMALLRECT];

imgView2.image = [UIImage imageNamed:@"two.png"];

imgView2.userInteractionEnabled = NO;

imgView2.tag = IMAGE_VIEW_2;

// image 1 is in front of image 2 to begin

[self addSubview:imgView2];

[self addSubview:imgView1];

isOne = YES;

[imgView1 release];

[imgView2 release];

return self;

}

- (void) touchesBegan:(NSSet*)touches withEvent:(UIEvent*)event

{

// Determine which view occupies which role

UIImageView *big = (UIImageView *)[self viewWithTag: (isOne ? IMAGE_VIEW_1 : IMAGE_VIEW_2)];

UIImageView *little = (UIImageView *)[self viewWithTag: (isOne ? IMAGE_VIEW_2 : IMAGE_VIEW_1)];

isOne = !isOne;

// Pack all the changes into the animation block

CGContextRef context = UIGraphicsGetCurrentContext();

[UIView beginAnimations:nil context:context];

[UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];

[UIView setAnimationDuration:1.0];

[big setFrame:SMALLRECT];

[big setAlpha:0.5];

[little setFrame:BIGRECT];

[little setAlpha:1.0];

[UIView commitAnimations];

// Hide the shrunken "big" image.

[big setAlpha:0.0f];

[[big superview] bringSubviewToFront:big];

}

@end

@interface HelloController : UIViewController

@end

@implementation HelloController

- (void)loadView

{

ToggleView *contentView = [[ToggleView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]];

contentView.backgroundColor = [UIColor whiteColor];

self.view = contentView;

[contentView release];

}

@end

@interface SampleAppDelegate : NSObject <UIApplicationDelegate>

@end

@implementation SampleAppDelegate

- (void)applicationDidFinishLaunching:(UIApplication *)application {

UIWindow *window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];

HelloController *hello = [[HelloController alloc] init];

[window addSubview:hello.view];

[window makeKeyAndVisible];

}

@end

int main(int argc, char *argv[])

{

NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];

int retVal = UIApplicationMain(argc, argv, nil, @"SampleAppDelegate");

[pool release];

return retVal;

}

最重要的动画代码

[cpp] view
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- (void) touchesBegan:(NSSet*)touches withEvent:(UIEvent*)event

{

// 這一段代碼,設定目前哪一張圖是大圖,哪一張是小圖

UIImageView *big = (UIImageView *)[self viewWithTag: (isOne ? IMAGE_VIEW_1 : IMAGE_VIEW_2)];

UIImageView *little = (UIImageView *)[self viewWithTag: (isOne ? IMAGE_VIEW_2 : IMAGE_VIEW_1)];

isOne = !isOne;

// 這是使用動畫的一些基本設定

CGContextRef context = UIGraphicsGetCurrentContext();

[UIView beginAnimations:nil context:context];

[UIView setAnimationCurve:UIViewAnimationCurveEaseInOut]; // 設定為IN OUT的動畫

[UIView setAnimationDuration:1.0]; // 動畫時間為一秒

[big setFrame:SMALLRECT];

[big setAlpha:0.5];

[little setFrame:BIGRECT];

[little setAlpha:1.0];

[UIView commitAnimations];

// Hide the shrunken "big" image.

[big setAlpha:0.0f];

[[big superview] bringSubviewToFront:big];

}

@end



代码中设定透明度的目的,为了就是小图放大的时候,才不会被原本在上面的大图盖到,导致看不到图