用iCarousel缩放项目

Question

我试图用iCarousel作为我的解决方案之一，我需要实现如下所示的东西

​

它应该是正确的方式

iCarouselOptionFadeMin iCarouselOptionFadeMax iCarouselOptionFadeRange iCarouselOptionFadeMinAlpha使用

- (CGFloat)carousel:(iCarousel *)carousel valueForOption:(iCarouselOption)option withDefault:(CGFloat)value

我试着创建一个和

- (CGFloat)alphaForItemWithOffset:(CGFloat)offset

我发现它是用offset值来完成的，但是事情没有用，有人能帮我实现这个目标吗？

谢谢。

Answer 1

您可以通过委托方法中的iCarousel的iCarouselTypeCustom类型来完成这一任务。

- (CATransform3D)carousel:(iCarousel *)carousel itemTransformForOffset:(CGFloat)offset baseTransform:(CATransform3D)transform

只需设置旋转木马的类型(例如，在旋转木马视图控制器的viewDidLoad中)：

self.carousel.type = iCarouselTypeCustom;

然后计算出你喜欢的变换。我把物体放在双曲线上，当它们离开中心的时候，再把它们缩小一些。很像你的形象，我想：

- (CATransform3D)carousel:(iCarousel *)carousel itemTransformForOffset:(CGFloat)offset baseTransform:(CATransform3D)transform
{
    const CGFloat offsetFactor = [self carousel:carousel valueForOption:iCarouselOptionSpacing withDefault:1.0f]*carousel.itemWidth;

    //The larger these values, as the items move away from the center ...

    //... the faster they move to the back
    const CGFloat zFactor = 150.0f;

    //... the faster they move to the bottom of the screen
    const CGFloat normalFactor = 50.0f;

    //... the faster they shrink
    const CGFloat shrinkFactor = 3.0f;

    //hyperbola
    CGFloat f = sqrtf(offset*offset+1)-1;

    transform = CATransform3DTranslate(transform, offset*offsetFactor, f*normalFactor, f*(-zFactor));
    transform = CATransform3DScale(transform, 1/(f/shrinkFactor+1.0f), 1/(f/shrinkFactor+1.0f), 1.0);
    return transform;
}

其结果是：

​

您可以根据需要调整浮动常量。

对于在圆圈内移动的物品，只需使用角度测量函数进行平移，然后旋转和缩放：

- (CGFloat)carousel:(iCarousel *)carousel valueForOption:(iCarouselOption)option withDefault:(CGFloat)value
{
    if (option == iCarouselOptionSpacing)
    {
        return value * 2.0f;
    }
    if(option == iCarouselOptionVisibleItems)
    {
        return 11;
    }
    if(option == iCarouselOptionWrap) return YES;
    return value;
}

- (CATransform3D)carousel:(iCarousel *)carousel itemTransformForOffset:(CGFloat)offset baseTransform:(CATransform3D)transform
{
    const CGFloat radius = [self carousel:carousel valueForOption:iCarouselOptionRadius withDefault:200.0];
    const CGFloat offsetFactor = [self carousel:carousel valueForOption:iCarouselOptionSpacing withDefault:1.0f]*carousel.itemWidth;
    const CGFloat angle = offset*offsetFactor/radius;

    //... the faster they shrink
    const CGFloat shrinkFactor = 2.0f;
    //hyperbola (now only for shrinking purposes)
    CGFloat f = sqrtf(offset*offset+1)-1;


    transform = CATransform3DTranslate(transform, radius*sinf(angle), radius*(1-cosf(angle)), 0.0);
    transform = CATransform3DRotate(transform, angle, 0, 0, 1);
    transform = CATransform3DScale(transform, 1/(f*shrinkFactor+1.0f), 1/(f*shrinkFactor+1.0f), 1.0);
    return transform;
} 

同样，结果是：

​

您可以在carousel:valueForOption:withDefault:方法中调整间距和半径。

享受！:)

Answer 2

稍作修改，并在SWIFT中复制粘贴;) -为我工作

func carousel(carousel: iCarousel, valueForOption option: iCarouselOption, withDefault value: CGFloat) -> CGFloat {
    if option == iCarouselOption.Spacing {
        return value * 1.8
    }
    return value
}

func carousel(carousel: iCarousel, itemTransformForOffset offset: CGFloat, baseTransform transform: CATransform3D) -> CATransform3D {
    let offsetFactor = self.carousel(carousel, valueForOption: iCarouselOption.Spacing, withDefault: 1) * carousel.itemWidth

    let zFactor: CGFloat = 150
    let normalFactor: CGFloat = 0
    let shrinkFactor: CGFloat = 1
    let f = sqrt(offset*offset+1)-1

    var transform = CATransform3DTranslate(transform, offset*offsetFactor, f*normalFactor, f*(-zFactor));
    transform = CATransform3DScale(transform, 1/(f/shrinkFactor+1), 1/(f/shrinkFactor+1), 1);
    return transform;
}

Answer 3

我没有足够的声誉发表评论，所以我不得不再提出一个问题作为回答：

@burax是否可以将项目布局在直线上而不是双曲线上，但要保持调整大小？

你好，很抱歉这样问

编辑:通过随机尝试，我完成了以下操作：

- (CATransform3D)carousel:(iCarousel *)carousel itemTransformForOffset:(CGFloat)offset baseTransform:(CATransform3D)transform
{
const CGFloat radius = [self carousel:carousel valueForOption:iCarouselOptionRadius withDefault:5050.0];
const CGFloat offsetFactor = [self carousel:carousel valueForOption:iCarouselOptionSpacing withDefault:0.8f]*carousel.itemWidth;
const CGFloat angle = offset*offsetFactor/radius;

//... the faster they shrink
const CGFloat shrinkFactor = 2.0f;
//hyperbola (now only for shrinking purposes)
CGFloat f = sqrtf(offset*offset+1)-1;


transform = CATransform3DTranslate(transform, radius*sinf(angle), radius*(1-cosf(angle)), 0.0);
transform = CATransform3DRotate(transform, angle, 0, 0, 1);
transform = CATransform3DScale(transform, 1/(f*shrinkFactor+1.0f), 1/(f*shrinkFactor+1.0f), 1.0);
return transform;
}

也许有更好的方法，但我对转换还不熟悉:)