来自SKTexture的UIImage

Question

如何获得UIImage的SKTexture？

我试图让UIImage从SKTextureAtlas,但似乎不是工作压力太大:

// p40_prop1 is a part of SKTextureAtlas
UIImage *image = [UIImage imageNamed:@"p40_prop1"];

image 没有.

Answer 1

这似乎对我有用:

- (UIImage*) imageWithView:(UIView *)view
{
    UIGraphicsBeginImageContextWithOptions(view.bounds.size, view.opaque, 0.0);

    [view drawViewHierarchyInRect:view.bounds afterScreenUpdates:YES];

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

    return img;
}


- (UIImage*) imageFromNode:(SKNode*)node
{
    SKTexture*      tex     = [self.scene.view textureFromNode:node];
    SKView*         view    = [[SKView alloc]initWithFrame:CGRectMake(0, 0, tex.size.width, tex.size.height)];
    SKScene*        scene   = [SKScene sceneWithSize:tex.size];
    SKSpriteNode*   sprite  = [SKSpriteNode spriteNodeWithTexture:tex];
    sprite.position = CGPointMake( CGRectGetMidX(view.frame), CGRectGetMidY(view.frame) );
    [scene addChild:sprite];
    [view presentScene:scene];

    return [self imageWithView:view];
}

1. 使用当前的SKView获取节点的SKTexture
2. 制作另一个足够大的纹理SKView
3. 将带有纹理的SKSpriteNode添加到新场景中,将其放在中间
4. 将视图渲染到图形上下文中

或者对于喜欢Swift的人:

func imageWithView(view : UIView) -> UIImage {
    UIGraphicsBeginImageContextWithOptions(view.bounds.size, view.opaque, 0.0)
    view.drawViewHierarchyInRect(view.bounds, afterScreenUpdates: true)
    let img = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    return img
}

func imageFromNode(node : SKNode) -> UIImage? {
    if let tex = self.scene?.view?.textureFromNode(node) {
        let view = SKView(frame:CGRectMake(0, 0, tex.size().width, tex.size().height))
        let scene = SKScene(size: tex.size())
        let sprite  = SKSpriteNode(texture: tex)
        sprite.position = CGPoint(x: CGRectGetMidX(view.frame), y: CGRectGetMidY(view.frame))
        scene.addChild(sprite)
        view.presentScene(scene)
        return self.imageWithView(view)
    }
    return nil
}

Answer 2

从iOS 9开始,这是一块蛋糕.SKTexture现在有CGImage属性,属于CGImageRef类型.因此,从纹理中获取图像现在只需一行:

let image : UIImage = UIImage(CGImage:texture.CGImage)

Answer 3

实际上有一种方法可以在iOS 7.0中从SKView中获取UIImage!

它使用常规UIView API将视图呈现为ImageContext,然后从中拉出UIImage.但是,该解决方案的范围非常有限.它将SKView绘制到UIImage中,然后裁剪生成的图像以适合给定节点的帧.因此,一定不能覆盖要快照的节点.此外,视图和场景都必须在屏幕上可见(这比通常的-[SKView textureFromNode:]方法更严格).甚至还有一些我没有发现的限制.

鉴于这一切,这个程序仍然足以满足我的需要,所以我认为值得分享.

+(UIImage *)imageFromNode:(SKNode *)node {
    SKView *view = node.scene.view;
    CGFloat scale = [UIScreen mainScreen].scale;
    CGRect nodeFrame = [node calculateAccumulatedFrame];

    // render SKView into UIImage
    UIGraphicsBeginImageContextWithOptions(view.bounds.size, YES, 0.0);
    [view drawViewHierarchyInRect:view.bounds afterScreenUpdates:YES];
    UIImage *sceneSnapshot = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    // crop to the requested node (making sure to flip the y-coordinate)
    CGFloat originY = sceneSnapshot.size.height*scale - nodeFrame.origin.y*scale - nodeFrame.size.height*scale;   
    CGRect cropRect = CGRectMake(nodeFrame.origin.x * scale, originY, nodeFrame.size.width*scale, nodeFrame.size.height*scale);
    CGImageRef croppedSnapshot = CGImageCreateWithImageInRect(sceneSnapshot.CGImage, cropRect);
    UIImage *nodeSnapshot = [UIImage imageWithCGImage:croppedSnapshot];
    CGImageRelease(croppedSnapshot);

    return nodeSnapshot;
}

我在模拟器上用3.5英寸和4英寸视网膜iPhone,视网膜和非视网膜iPad测试了这个.至于实际设备,它适用于iPhone 4S,iPhone 5S和iPad 2,均运行7.0.4.