iOS - 图片实现多层折叠效果
本文是投稿文章,作者: Resory
序
在网上能找到挺多图片折叠效果的教程,但大多数是一层折叠,在他们的教程的基础上,我试着实现了一下多层折叠的效果。操作如下~
效果
Demo
Demo地址: https://github.com/Resory/RYMutipleFoldImageView
如果官人喜欢的话不妨给个星星吧。
逻辑
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在做图片折叠效果的时候,我们可以理解为把图片分成几部分,然后分别对各部分做动效来实现折叠效果。
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根据动态图,可以看到这是一张大图"分成"4个小imageView。从上至下,我们分别命名为one,two,three,four
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对one,two,three,four这四个小imageView进行旋转+移动。旋转的时候,关键是看各个imageView的anchorPoint是多少.而我们这里,可看p1图中的红点。
1.a1代表one的anchorPoint为(0.5,0.0)
2.a2代表two的anchorPoint为(0.5,1.0)
3.a3代表three的anchorPoint为(0.5,0.0)
4.a4代表four的anchorPoint为(0.5,1.0)
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旋转: 我们这里的imageView都是旋转45°或者是-45°,这个用CATransform3DRotate即可完成。
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移动(关键):
1.旋转后,各个imageView都会变形并且都一样大小,只有位置不一样,我们要根据这个旋转后的imageView高度来进行移动。
2.比如two要和one对接。根据动态图,one只有旋转,没有移动。而two则旋转和移动了。那么移动了多少呢。在没有折叠前,所有的imageView高度都是50px。也就是one和two总共加起来是100px。而折叠后。one和two都变小了。就是因为他们两个都变小了。所以中间就出现了缝隙,这个缝隙就是我们要移动的距离。而我们知道在二维空间中,总长度是100px,one,two的高度在旋转后是可以算出来的,也就是说缝隙的二维空间距离是:100-2*(one.frame.size.height)。,然后再经过CATransform3DMakeAffineTransform方法的转换得到真实地三维空间移动的距离。
实现
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初始化4个小imageView(contentsRect的运用)
- (void)configFourFoldImage { UIView *bgView = [[UIView alloc] initWithFrame:CGRectMake(10, 100, 300, IMAGE_PER_HEIGIT*4)]; [self.view addSubview:bgView]; // 把kiluya这张图,分成平均分成4个部分的imageview _one = [[UIImageView alloc] init]; _one.image = [UIImage imageNamed:@"Kiluya.jpg"]; _one.layer.contentsRect = CGRectMake(0, 0, 1, 0.25); _one.layer.anchorPoint = CGPointMake(0.5, 0.0); _one.frame = CGRectMake(0, 0, 300, IMAGE_PER_HEIGIT); _two = [[UIImageView alloc] init]; _two.image = [UIImage imageNamed:@"Kiluya.jpg"]; _two.layer.contentsRect = CGRectMake(0, 0.25, 1, 0.25); _two.layer.anchorPoint = CGPointMake(0.5, 1.0); _two.frame = CGRectMake(0, IMAGE_PER_HEIGIT, 300, IMAGE_PER_HEIGIT); _three = [[UIImageView alloc] init]; _three.image = [UIImage imageNamed:@"Kiluya.jpg"]; _three.layer.contentsRect = CGRectMake(0, 0.5, 1, 0.25); _three.layer.anchorPoint = CGPointMake(0.5, 0.0); _three.frame = CGRectMake(0, IMAGE_PER_HEIGIT*2, 300, IMAGE_PER_HEIGIT); _four = [[UIImageView alloc] init]; _four.image = [UIImage imageNamed:@"Kiluya.jpg"]; _four.layer.contentsRect = CGRectMake(0, 0.75, 1, 0.25); _four.layer.anchorPoint = CGPointMake(0.5, 1.0); _four.frame = CGRectMake(0, IMAGE_PER_HEIGIT*3, 300, IMAGE_PER_HEIGIT); [bgView addSubview:_one]; [bgView addSubview:_two]; [bgView addSubview:_three]; [bgView addSubview:_four]; // 给第一张和第三张添加阴影 _oneShadowView = [[UIView alloc] initWithFrame:_one.bounds]; _oneShadowView.backgroundColor = [UIColor blackColor]; _oneShadowView.alpha = 0.0; _threeShadowView = [[UIView alloc] initWithFrame:_three.bounds]; _threeShadowView.backgroundColor = [UIColor blackColor]; _threeShadowView.alpha = 0.0; [_one addSubview:_oneShadowView]; [_three addSubview:_threeShadowView]; }
生成折叠动效需要的CATransform3D
- (CATransform3D)config3DTransformWithRotateAngle:(double)angle andPositionY:(double)y { CATransform3D transform = CATransform3DIdentity; // 立体 transform.m34 = -1/1000.0; // 旋转 CATransform3D rotateTransform = CATransform3DRotate(transform, M_PI*angle/180, 1, 0, 0); // 移动(这里的y坐标是平面移动的的距离,我们要把他转换成3D移动的距离.这是关键,没有它,图片就没办法很好地对接。) CATransform3D moveTransform = CATransform3DMakeAffineTransform(CGAffineTransformMakeTranslation(0, y)); // 合并 CATransform3D concatTransform = CATransform3DConcat(rotateTransform, moveTransform); return concatTransform; }
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折叠
// 动效是否执行中 static bool isFolding = NO; - (IBAction)fold:(id)sender { if(!isFolding) { isFolding = YES; [UIView animateWithDuration:1.0 delay:0 usingSpringWithDamping:1.0 initialSpringVelocity:0 options:UIViewAnimationOptionCurveLinear animations:^{ // 阴影显示 _oneShadowView.alpha = 0.2; _threeShadowView.alpha = 0.2; // 折叠 _one.layer.transform = [self config3DTransformWithRotateAngle:-45.0 andPositionY:0]; _two.layer.transform = [self config3DTransformWithRotateAngle:45.0 andPositionY:-100+2*_one.frame.size.height]; _three.layer.transform = [self config3DTransformWithRotateAngle:-45.0 andPositionY:-100+2*_one.frame.size.height]; _four.layer.transform = [self config3DTransformWithRotateAngle:45.0 andPositionY:-200+4*_one.frame.size.height]; } completion:^(BOOL finished) { if(finished) { isFolding = NO; } }]; } }
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恢复
- (IBAction)reset:(id)sender { isFolding = NO; [UIView animateWithDuration:1.0 delay:0 usingSpringWithDamping:1.0 initialSpringVelocity:0 options:UIViewAnimationOptionCurveLinear animations:^{ // 阴影隐藏 _oneShadowView.alpha = 0.0; _threeShadowView.alpha = 0.0; // 图片恢复原样 _one.layer.transform = CATransform3DIdentity; _two.layer.transform = CATransform3DIdentity; _three.layer.transform = CATransform3DIdentity; _four.layer.transform = CATransform3DIdentity; } completion:^(BOOL finished) { }]; }
末
这里关键是缝隙的计算,这个想明白了。其他就没什么了。
如果你有疑问或者发现错误请留言给我,喜欢就点个赞吧!3Q