捏合圖片放大縮小與移動

2019-11-14 18:11:14

字體：大中小

來源：轉載

供稿：網友

最近在做自定義地圖的放大縮小與移動,雖然實現了主要功能,但是在細節上還是有很多缺陷瑕疵,在這里將代碼和思路分享一下,希望能夠拋磚引玉,得到高人指點.

實現圖片的放大與縮小,我的思路是先通過兩個觸摸點距離的變化,判斷是放大還是縮小,然后再把地圖圖片按比例放大縮小.

地圖的移動,先記錄觸摸開始時的位置和觸摸移動的位置,計算兩者之間的差,再相應更改地圖圖片的位置.兩個記錄點不斷更新,所以圖片位置也隨著手指的變動不斷移動.

基本思路介紹完了,以下是代碼.

1.因為圖片是全屏的,同時還要考慮不同尺寸的屏幕,所以宏定義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文件中放入一個imageView,大小為全屏,設置約束,并關聯.h文件

觸摸點進行比較時需要至少兩個比較對象,所以在.h中需要聲明

double lastdistance;//在捏合手勢中用來記錄上一次兩點之間距離

@PRoperty(nonatomic,assign)CGPoint lastPoint;//移動時記錄上一次位置

3.允許當前view執行觸摸事件

self.view.multipleTouchEnabled=YES;

在寫的時候我將圖片的放大縮小移動寫在了一起,但是為了方便理解,在這里我將他們按功能分開

4.圖片放大縮小

-(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];        //計算兩點距離[(x1-x2)^2+(y1-y2)^2]開方        double distance=[self distance:point1 point:point2];        //在手指剛觸摸屏幕時給last distance賦值,防止在手指捏合時因為last distance為空,造成第一次相減差太大,圖片放大比例太高       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;//計算放大倍數     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; }//放大圖片-(void)bigImageWithImage:(UIImageView *)image Size:(CGSize)size{    self.image.center=self.view.center;    self.image.bounds=CGRectMake(0, 0, size.width, size.height);}//縮小圖片-(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);    }}

圖片移動

-(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];     } }//移動圖片-(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;    //判斷,防止圖片越界    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;}