我正在根据图像创建视频,并在其上添加叠加层。问题是当我尝试将CATextLayer添加到视频时。文本已像素化,请查看图像
这是用于生成CATextLayer的代码:
private func generateTextLayer(for text: String, at frame: CGRect, in layer: CALayer) -> CATextLayer {
let textLayer = CATextLayer()
textLayer.frame = frame.integral
textLayer.contentsScale = UIScreen.main.scale
textLayer.isWrapped = true
textLayer.isHidden = true
textLayer.foregroundColor = UIColor.white.cgColor
textLayer.backgroundColor = UIColor.clear.cgColor
let fontHeight = resolution.fontHeight
textLayer.font = UIFont.systemFont(ofSize: fontHeight)
textLayer.fontSize = fontHeight
textLayer.string = text
textLayer.truncationMode = .end
textLayer.alignmentMode = .center
textLayer.contentsScale = UIScreen.main.scale
layer.addSublayer(textLayer)
return textLayer
}
并且此代码用于生成带有图像的CALayer:
private func generateImageLayer(for image: CGImage?, at frame: CGRect, in layer: CALayer) -> CALayer {
let imageLayer = CALayer()
imageLayer.frame = frame.integral
imageLayer.contents = image
imageLayer.contentsGravity = .resizeAspectFill
imageLayer.isHidden = true
imageLayer.backgroundColor = UIColor.clear.cgColor
layer.addSublayer(imageLayer)
return imageLayer
}
由于生成的视频中不同图像层的动画,图像层被隐藏。这是用于生成图层的代码:
let size = backgroundTrack.naturalSize.applying(backgroundTrack.preferredTransform)
let parentlayer = CALayer()
parentlayer.frame = CGRect(origin: .zero, size: size).integral
parentlayer.backgroundColor = UIColor.black.cgColor
parentlayer.isOpaque = true
let backgroundVideoLayer = CALayer()
backgroundVideoLayer.frame = parentlayer.bounds
backgroundVideoLayer.backgroundColor = UIColor.black.cgColor
backgroundVideoLayer.isOpaque = true
parentlayer.addSublayer(backgroundVideoLayer)
var currentTime: Double = 0
for source in videoSources {
// This will generate blurred background layer
let blurrLayer = generateImageLayer(for: source.blurredImage, at: backgroundVideoLayer.bounds, in: backgroundVideoLayer)
blurrLayer.contentsGravity = .resizeAspectFill
// Adds image to blurrLayer
if let image = source.image {
let frame = calculateFrame(for: image.size)
let imageLayer = generateImageLayer(for: image.cgImage, at: frame, in: blurrLayer)
imageLayer.isHidden = false
Animations.fadeInOut(layer: blurrLayer, beginTime: currentTime, duration: duration.value)
}
// Adds CATextLayer
if let text = source.title {
let frame = parentlayer.bounds.offsetBy(dx: 0, dy: 100)
let titleLayer = generateTextLayer(for: text, at: frame, in: parentlayer)
Animations.fadeInOut(layer: titleLayer, beginTime: currentTime, duration: duration.value)
}
currentTime += duration.value
}
我尝试将rasterizationScale设置为UIScreen.main.scale,应该将rasterize设置为true,contentsScale设置为UIScreen.main.scale,各种不同的选项,甚至尝试对UILabel进行快照并将其设置为图像(甚至本地保存并检查图像,质量很好),但结果再次是像素化写作。
Animate fadeInOut基本上是三种动画,一种是将隐藏参数设置为true或false,另一种是添加CATransition显示动画,以便在层之间进行入口和出口过渡。
static func fadeInOut(layer: CALayer, beginTime: Double, duration: Double, skipEntry: Bool = false) {
let t = beginTime < 1 ? -0.0001 : beginTime
let d = beginTime < 1 ? duration + 0.0001 : duration - 0.0001
if !skipEntry {
let entryTransition = CATransition()
entryTransition.beginTime = t
entryTransition.duration = 0.5
entryTransition.type = CATransitionType.reveal
entryTransition.subtype = CATransitionSubtype.fromTop
entryTransition.isRemovedOnCompletion = false
layer.add(entryTransition, forKey: "entry")
}
let exitTransition = CATransition()
exitTransition.beginTime = d - 0.5
exitTransition.duration = 0.5
exitTransition.startProgress = 1
exitTransition.endProgress = 0
exitTransition.type = CATransitionType.reveal
exitTransition.subtype = CATransitionSubtype.fromTop
exitTransition.isRemovedOnCompletion = false
layer.add(exitTransition, forKey: "exit")
let fadeInOutAnimation = CABasicAnimation(keyPath: "hidden")
fadeInOutAnimation.fromValue = false
fadeInOutAnimation.toValue = false
fadeInOutAnimation.beginTime = t
fadeInOutAnimation.duration = d
fadeInOutAnimation.isRemovedOnCompletion = false
layer.add(fadeInOutAnimation, forKey: "opacity")
}
在将我的问题标记为已经看到并回答之前,我花了很多时间尝试搜索可能的结果,并尝试了很多事情,但是结果仍然相同。
尝试在.contentsScale属性附近播放。我认为视频以videoComposition的比例呈现,而不是UIScreen.main.scale
因此,为了在生成视频时获得高质量的图像或文本,必须注意contentScale将其设置为1。我遇到的另一个问题是某些框架的问题,其中UIImageView或UITextField可以缩放所有内容以使其看起来清晰,而contentMode可以处理所有事情,而使用视频逻辑生成视频开发者必须特别注意这一点
我的意思是,如果图像比图层框架大,图像将缩小,但看起来像素化。为图层提供与图像相同的帧将使图像看起来不错。这在水印图像上尤为明显,在水印图像中,我们将图像放置到具有1x,2x和3x尺寸的资源中。使用UIImage(名称为“ my_watermark”)获取此图像后,它将加载3x尺寸,由于视频比例== 1,我们需要1x尺寸的视频。删除2x和3x尺寸可以解决此问题。
[当我们发现这一点时,我们对CATextLayer进行了相同的测试,因此将contentScale设置为1,并注意框架,就可以了。
通过遵循此逻辑生成的视频在内部具有高质量的文本和图像。最大的问题实际上是在播放设置后需要检查输出结果的时间,在这种情况下,生成视频会花费一些时间,然后将其传输到更大的屏幕上以检查所有内容都非常耗时。
希望此答案对某人有帮助!