在这个智能机的时代，触摸与手势应该是最基本的了。对于简单的点击控件而触发各种事件的触摸这里就不说了(比如点个按钮，点个文本框，表格的滑动，直接设置某些属性，链接某个函数就OK了)。这里主要写下关于图片的缩放。可以点击放大，缩小，根据手势扩大和缩小。就类似于QQ里的那种查看图片。
首先，我们得了解，触摸的操作对象是View而不是Controller。想想，如果是整个controller，在整个界面都会响应，那就麻烦了。
当我们在屏幕上触摸，比划手势，UIResponder类会响应这些触摸。我们通过重写它的方法而达到我们想要的效果
所以，我们首先得创建一个View的类，继承自UIView。
@interface DragView :UIImageView
{
CGPoint ptStartLocation;
BOOL bLarge;
float wRate;
float hRate;
float originWidth;
float originHeight;
CGFloat lastScale;
}
@property (assign,nonatomic)
float originWidth;
@property (assign,nonatomic)
float originHeight;
@property (assign,nonatomic)
float rate;
//下面两个方法是重写
-(void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event;
-(void) touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event;
@end
准备好一张大图
在ViewDidload里面加载图片，并缩小图片
drag = [[DragViewalloc]
initWithImage:[UIImageimageNamed:@"conan.jpg"]];
drag.originHeight =drag.frame.size.height;
drag.originWidth =drag.frame.size.width;
float showRate; //这个用来限定初始显示的图片的大小
if (drag.originHeight -44
> drag.originWidth)
{
showRate = SHOWSIZE /
drag.originHeight;
}
else
{
showRate = SHOWSIZE /
drag.originWidth;
}
//记录下水平与垂直方向的比例
float hRate =
self.view.frame.size.height /drag.originHeight;
float wRate =
self.view.frame.size.width /drag.originWidth;
if(wRate > hRate)
{
drag.rate = wRate;
}
else
{
drag.rate = hRate;
}
//[self.view addSubview:drag];
_scrollView.contentSize =CGSizeMake(drag.originWidth,drag.originHeight);
_scrollView.contentOffset =CGPointMake(drag.originWidth/2,drag.originHeight/2);
drag.frame =CGRectMake(20+_scrollView.contentOffset.x,100+_scrollView.contentOffset.y,drag.originWidth*showRate,drag.originHeight*showRate);
[_scrollView
addSubview:drag];
UIPinchGestureRecognizer *gesture = [[UIPinchGestureRecognizeralloc]
initWithTarget:selfaction:@selector(scale:)];
[dragaddGestureRecognizer:gesture];
gesture.delegate =
self;
[gesture release];
[drag release];
手势的代理函数
-(BOOL) gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch
*)touch
{
return
YES;
}
下面就是手势缩放的处理
-(void) scale:(id) sender //缩放
{
//根据角度缩放
if ([(UIPinchGestureRecognizer *) senderstate] ==
UIGestureRecognizerStateBegan)
{
lastScale =
1.0;
}
else
{
CGFloat scale =
lastScale - ((1.0 -[(UIPinchGestureRecognizer *) senderscale])/2) ;
NSLog(@"scale:%f",scale);
CGAffineTransform currentTransform =
drag.transform;
CGAffineTransform newTransfrom =
CGAffineTransformScale(currentTransform, scale, scale);
[dragsetTransform: newTransfrom];
lastScale = [(UIPinchGestureRecognizer *) senderscale];
NSLog(@"lastscale:%f",lastScale);
}
}
特别说明：CGAffineTransform
大家或许对CGAffineTransform不是很了解。我也不是很了解。查了些资料，在纸上画呀，算呀的研究了下，明白了一点点。
它其实是一个矩阵，仿射变换矩阵
起始点：orgin[X,Y,1] transform |a b 0|
|c d 0|
|tx ty 1|
orgin = [aX + cY+tx,bX+dY+ty];
下面是图片的3种基本的操作
缩放
CGAffineTransformScale(currentTransform, scale, scale);
scale,scale是X，Y上面的缩放量。如果要使图片不变形，X，Y上的缩放量应该是一致的。
旋转
CGAffineTransformRotate(transform, scale);
transform表示以此transform为基础
scale代表旋转角度
平移
CGAffineTransformMakeTranslation(CGFloat tx, CGFloat ty);
tx:X方向上的平移量
ty:Y方向上的平移量
再来看下我们新建的类重写的UITouch的几个函数。这里只重写touchesEnded函数，因为上面加载图片时使用了UISCrollerView.
图片加载在ScrollerView里面。ScrollerView已经重写了那些函数，我们就不必再写了。
-(void) touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event //触摸接触
{
UITouch *touch = [touches
anyObject]; //这里从一个集合中取一个touch
//单击事件处理，使图片与屏幕一样大
if (touch.tapCount ==1)
{
self.frame =CGRectMake(0.0f,0.0f
,originWidth * rate,originHeight *
rate);
self.center =CGPointMake([selfsuperview].frame.size.width/2
+originWidth/2, [selfsuperview].frame.size.height
/2 +originHeight/2);
[UIApplicationsharedApplication].statusBarHidden =NO;
}
//双击事件处理，扩大图片为原图的大小
if(touch.tapCount ==2)
{
if (bLarge)
{
bLarge = !bLarge;
self.frame =CGRectMake(0.0f,40.0f
,originWidth * rate,originHeight *
rate);
[UIApplicationsharedApplication].statusBarHidden =NO;
self.center =CGPointMake(originWidth/2,originHeight/2);
}
else
{
bLarge = !bLarge;
self.frame =CGRectMake(0.0f,-20.0f
,originWidth, originHeight);
[UIApplicationsharedApplication].statusBarHidden =YES;
self.center =CGPointMake(originWidth/2,originHeight/2);
}
}
如果没有用到scrollerView，则重写begin和moved函数
-(void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event //触摸开始
{
CGPoint pt = [[touches
anyObject] locationInView:self];
ptStartLocation = pt;
[[selfsuperview]
bringSubviewToFront:self];
}
-(void) touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event//触摸移动过程中
{
// Calculate offset
CGPoint pt = [[touchesanyObject]
locationInView:self];
float dx = pt.x -ptStartLocation.x;
float dy = pt.y -ptStartLocation.y;
CGPoint newcenter =CGPointMake(self.center.x
+ dx,self.center.y + dy);
// Set new location
self.center = newcenter;
}