捏合图片放大缩小与移动
2025-03-01 10:43:15 来源: 阅读:
最近在做自定义地图的放大缩小与移动,虽然实现了主要功能,但是在细节上还是有很多缺陷瑕疵,在这里将代码和思路分享一下,希望能够抛砖引玉,得到高人指点.
实现图片的放大与缩小,我的思路是先通过两个触摸点距离的变化,判断是放大还是缩小,然后再把地图图片按比例放大缩小.
地图的移动,先记录触摸开始时的位置和触摸移动的位置,计算两者之间的差,再相应更改地图图片的位置.两个记录点不断更新,所以图片位置也随着手指的变动不断移动.
基本思路介绍完了,以下是代码.
1.因为图片是全屏的,同时还要考虑不同尺寸的屏幕,所以宏定义imageView的大小(屏幕的大小)
#define SCREENHEIGHT [[UIScreen mainScreen] bounds].size.height
#define SCREENWIDTH [[UIScreen mainScreen] bounds].size.width
2.在xib文件中放入一个imageView,大小为全屏,设置约束,并关联.h文件
触摸点进行比较时需要至少两个比较对象,所以在.h中需要声明
double lastdistance;//在捏合手势中用来记录上一次两点之间距离
@property(nonatomic,assign)CGPoint lastPoint;//移动时记录上一次位置
3.允许当前view执行触摸事件
self.view.multipleTouchEnabled=YES;
在写的时候我将图片的放大缩小移动写在了一起,但是为了方便理解,在这里我将他们按功能分开
4.图片放大缩小
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
if (touches.count==2) {
NSArray *touchArray=[touches allObjects];
UITouch *firstTouch=[touchArray objectAtIndex:0];
UITouch *secondTouch=[touchArray objectAtIndex:1];
CGPoint point1=[firstTouch locationInView:self.view];
CGPoint point2=[secondTouch locationInView:self.view];
//计算两点距离[(x1-x2)^2+(y1-y2)^2]开方
double distance=[self distance:point1 point:point2];
//在手指刚触摸屏幕时给last distance赋值,防止在手指捏合时因为last distance为空,造成第一次相减差太大,图片放大比例太高
lastdistance=distance;
}
}
-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
if (touches.count==2) {
NSArray *touchArray=[touches allObjects];
UITouch *firstTouch=[touchArray objectAtIndex:0];
UITouch *secondTouch=[touchArray objectAtIndex:1];
CGPoint point1=[firstTouch locationInView:self.view];
CGPoint point2=[secondTouch locationInView:self.view];
double distance=[self distance:point1 point:point2];
if(distance-lastdistance>0)
{
int a=distance-lastdistance;
//计算放大倍数
float times=1+a*0.005;
CGSize bigSize=CGSizeMake(self.image.frame.size.width*times, self.image.frame.size.height*times);
[self bigImageWithImage:self.image Size:bigSize];
}
else
{
int a=lastdistance-distance;
float times=1-a*0.005;
CGSize smallSize=CGSizeMake(self.image.frame.size.width*times, self.image.frame.size.height*times);
[self smallImageWithImage:self.image Size:smallSize];
}
lastdistance=distance;
}
}
-(double)distance:(CGPoint)p1 point:(CGPoint)p2
{
double distance=sqrt(pow(p1.x-p2.x,2)+pow(p1.y-p2.y,2));
return distance;
}
//放大图片
-(void)bigImageWithImage:(UIImageView *)image Size:(CGSize)size
{
self.image.center=self.view.center;
self.image.bounds=CGRectMake(0, 0, size.width, size.height);
}
//缩小图片
-(void)smallImageWithImage:(UIImageView *)image Size:(CGSize)size
{
UIImageView *moveImage=image;
if (size.height<=SCREENHEIGHT&&size.width<=SCREENWIDTH) {
moveImage.center=self.view.center;
moveImage.bounds=CGRectMake(0, 0, SCREENWIDTH, SCREENHEIGHT);
}
else
{
self.image.center=self.view.center;
self.image.bounds=CGRectMake(0, 0, size.width, size.height);
}
}
图片移动
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
if (touches.count==1) {
UITouch *touch=[touches anyObject];
self.lastPoint=[touch locationInView:self.view];
}
}
-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
if (touches.count==1) {
UITouch *touch=[touches anyObject];
CGPoint movePoint=[touch locationInView:self.view];
[self moveImage:movePoint];
}
}
//移动图片
-(void)moveImage:(CGPoint)movePoint
{
float x = movePoint.x - self.lastPoint.x;
float y = movePoint.y - self.lastPoint.y;
float newX = self.image.frame.origin.x + x;
float newY = self.image.frame.origin.y + y;
//判断,防止图片越界
if (newX > 0) {
newX = 0;
}
if (newX < SCREENWIDTH-self.image.frame.size.width) {
newX = SCREENWIDTH-self.image.frame.size.width;
}
if (newY > 0) {
newY = 0;
}
if (newY < SCREENHEIGHT-self.image.frame.size.height) {
newY = SCREENHEIGHT-self.image.frame.size.height;
}
self.image.frame = CGRectMake(newX, newY, self.image.frame.size.width, self.image.frame.size.height);
self.lastPoint = movePoint;
}
功能实现最大的缺陷是每次放大图片的中心会重新定位到屏幕中心,在那里捏合就在那里放大.如果有更好地方法请告诉我.
下面是效果演示:
图片放大与移动:
