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:
