加载整个图像并使用 CATiledLayer

Question

我不确定我是否很好地理解了苹果文档中的内容。我正在考虑使用 CATiledLayer 来显示 JPEG 图像。然而，我只有整个 JPEG 文件可供使用，没有小图块。是否仍然可以使用 CATiledLayer 并让它“平铺”JPEG？

谢谢！

Answer 1

不可以。不幸的是，您必须自己贴瓷砖。 Core Animation 上的WWDC 2010 视频讨论了如何执行此操作并在其示例代码中，他们演示了当图块已经存在时如何使用 CATileLayer。

更正

我的意思是观看滚动视图会话。第 104 节“使用滚动视图设计应用程序”

Answer 2

您可以使用它在滚动视图中制作具有图像和缩放功能的 CATileLayer。

- (void)viewDidLoad
{
    [super viewDidLoad];

    // You do not need to and must not autorelease [NSBundle mainBundle]
    NSString *path = [[NSBundle mainBundle] pathForResource:@"img" ofType:@"jpg"];
    NSData *data = [NSData dataWithContentsOfFile:path];
    image = [UIImage imageWithData:data];

    //    CGRect pageRect = CGRectMake(0,  0,  1600, 2400);

    CGRect pageRect = CGRectMake(0.0, 0.0,  image.size.width, image.size.height);


    CATiledLayer *tiledLayer = [CATiledLayer layer];
    tiledLayer.delegate = self;
    tiledLayer.tileSize = CGSizeMake(256.0, 256.0);
    tiledLayer.levelsOfDetail = 5; // was 1000, which makes no sense. Each level of detail is a power of 2.
    tiledLayer.levelsOfDetailBias = 5; // was 1000, which also makes no sense.
    // Do not change the tiledLayer.frame.
    tiledLayer.bounds = pageRect; // I think you meant bounds instead of frame.
    // Flip the image vertically.
    tiledLayer.transform = CATransform3DMakeScale(1.0f, -1.0F, 1.0f);

    myContentView = [[UIView alloc] initWithFrame:CGRectMake(500,400,image.size.width,image.size.height)];
    [myContentView.layer addSublayer:tiledLayer];

    //    UIScrollView *scrollView = [[UIScrollView alloc] initWithFrame:self.view.bounds];
    scrollView=[[UIScrollView alloc]initWithFrame:CGRectMake(10, 10, 300, 400)];
    scrollView.backgroundColor = [UIColor whiteColor];
    //  [scrollView setContentSize:CGSizeMake(image.size.width,image.size.height)];
    [scrollView setContentSize:image.size];
    scrollView.maximumZoomScale = 32; // = 2 ^ 5
    scrollView.delegate = self;
    //    scrollView.contentSize = pageRect.size;


    [scrollView addSubview:myContentView];

    [self.view addSubview:scrollView];

}

- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
    return myContentView;
}

- (void)drawLayer:(CALayer *)layer inContext:(CGContextRef)context
{
    NSString *path = [[NSBundle mainBundle] pathForResource:@"img" ofType:@"jpg"];
    NSData *data = [NSData dataWithContentsOfFile:path];
    image = [UIImage imageWithData:data];
    CGRect imageRect = CGRectMake (0.0, 0.0, image.size.width, image.size.height);

    CGContextDrawImage (context, imageRect, [image CGImage]);
}

Answer 3

更简单的方法是缩小图像直到适合（我认为设备最多支持 2044x2044 左右）。您可以使用 CGImageCreateWithImageInRect() 创建 CGImage 的子图像