ios - 将 CATransform3D 转换为 CIVector 的 CIPerspectiveTransform，替换 UIGetScreenImage

Question

是否可以将 CATransform3D 转换为一组 CIVectors，以便使用 CATransform3D UIImage?

我相信现在终于有可能取代 UIGetScreenImage() 通过遍历 View 层次结构和渲染将 UIView/CALayer 的 3D 变换展平为图像的能力单个图像，然后将 CATransform3D 应用于创建的图像。

我开始使用 GPUImage，它确实接受 CATransform3Ds 以应用于 UIImage，但遗憾的是没有成功。附件是我使用的代码，以及生成的图像的链接。

Screenshot of Simulator

Image Produced

- (UIImage*)iterateLayerHierarchy:(CALayer*)layer
{
    UIGraphicsBeginImageContextWithOptions(CGSizeMake(layer.frame.size.width,
                                                      layer.frame.size.height),
                                           NO,
                                           0.0);


    for (CALayer *sublayer in layer.sublayers)
    {
        UIImage* subImage;

        if (sublayer.sublayers.count > 1) {
            subImage = [self iterateLayerHierarchy:sublayer];
        } else {
            subImage = [UIView getImageFromLayer:sublayer];
        }
        CGRect imageRect;
        if (isRetina()) {
            imageRect = CGRectMake(sublayer.position.x-subImage.size.width/4,
                                   sublayer.position.y-subImage.size.height/4,
                                   subImage.size.width,
                                   subImage.size.height);
        }else{
            imageRect = CGRectMake(sublayer.position.x-subImage.size.width/2,
                                   sublayer.position.y-subImage.size.height/2,
                                   subImage.size.width,
                                   subImage.size.height);
        }
        [subImage drawInRect:imageRect];
        //sublayer.hidden = YES;
    }

    UIImage * img = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return img;
}


+ (UIImage*) getImageFromLayer:(CALayer *)layer
{
    UIGraphicsBeginImageContextWithOptions(CGSizeMake(layer.bounds.size.width,
                                                      layer.bounds.size.height),
                                           NO,
                                           0.0);

    [layer renderInContext:UIGraphicsGetCurrentContext()];

    UIImage * img = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    if (!CATransform3DEqualToTransform(layer.transform, CATransform3DIdentity))
    {
        GPUImageTransformFilter *transformFilter = [[GPUImageTransformFilter alloc] init];
        transformFilter.transform3D = layer.transform;
        img = [transformFilter imageByFilteringImage:img];
    }

    return img;
}

Answer 1

虽然不是问题的直接答案，但从 iOS 7 开始，不再需要解决这个问题。 “UIGetScreenImage()”实际上已被“drawViewHierarchyInRect:”取代，后者能够同时捕获 OpenGL 层和基于 UIKit 的 View 。