[英]How to get two views to be the same width and height using CGAffineTransform
如果我想獲得 2 個具有相同寬度和高度的視圖,並且它們的中心都位於屏幕中間,我使用下面的代碼可以正常工作。 兩者並排在屏幕中間,具有相同的確切寬度和高度。
let width = view.frame.width
let insideRect = CGRect(x: 0, y: 0, width: width / 2, height: .infinity)
let rect = AVMakeRect(aspectRatio: CGSize(width: 9, height: 16), insideRect: insideRect)
// blue
leftView.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true
leftView.leadingAnchor.constraint(equalTo: view.leadingAnchor).isActive = true
leftView.widthAnchor.constraint(equalToConstant: rect.width).isActive = true
leftView.heightAnchor.constraint(equalToConstant: rect.height).isActive = true
// purple
rightView.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true
rightView.trailingAnchor.constraint(equalTo: view.trailingAnchor).isActive = true
rightView.widthAnchor.constraint(equalToConstant: leftView.widthAnchor).isActive = true
rightView.heightAnchor.constraint(equalToConstant: leftView.heightAnchor).isActive = true
如何使用CGAffineTransform
做同樣的事情? 我試圖找到一種方法使 rightView 與左視圖的大小相同,但不能。 leftView 框架的頂部位於屏幕中間而不是其中心,而 rightView 完全關閉。
let width = view.frame.width
let insideRect = CGRect(x: 0, y: 0, width: width / 2, height: .infinity)
let rect = AVMakeRect(aspectRatio: CGSize(width: 9, height: 16), insideRect: insideRect)
leftView.transform = CGAffineTransform(scaleX: 0.5, y: 0.5)
leftView.transform = CGAffineTransform(translationX: 0, y: view.frame.height / 2)
rightView.transform = leftView.transform
rightView.transform = CGAffineTransform(translationX: rect.width, y: view.frame.height / 2)
您需要根據合成視頻的output大小 - 它的.renderSize
進行轉換。
根據你的另一個問題...
因此,如果您有兩個1280.0 x 720.0
視頻,並且您希望它們在640 x 480
渲染幀中並排顯示,您需要:
320 x 480
0, 0
然后:
320 x 480
320, 0
所以你的比例變換將是:
let targetWidth = renderSize.width / 2.0
let targetHeight = renderSize.height
let widthScale = targetWidth / sourceVideoSize.width
let heightScale = targetHeight / sourceVideoSize.height
let scale = CGAffineTransform(scaleX: widthScale, y: heightScale)
那應該讓你到那里---除了......
在我的測試中,我拍攝了 4 個 8 秒的橫向視頻。
由於我不知道的原因-“本機”preferredTransforms 是:
Videos 1 & 3
[-1, 0, 0, -1, 1280, 720]
Videos 2 & 4
[1, 0, 0, 1, 0, 0]
因此,推薦的track.naturalSize.applying(track.preferredTransform)
返回的尺寸最終為:
Videos 1 & 3
-1280 x -720
Videos 2 & 4
1280 x 720
這與變換混淆。
經過一些實驗,如果大小為負數,我們需要:
這是一個完整的實現(最后沒有保存到磁盤):
import UIKit
import AVFoundation
class VideoViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
view.backgroundColor = .systemYellow
}
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
guard let originalVideoURL1 = Bundle.main.url(forResource: "video1", withExtension: "mov"),
let originalVideoURL2 = Bundle.main.url(forResource: "video2", withExtension: "mov")
else { return }
let firstAsset = AVURLAsset(url: originalVideoURL1)
let secondAsset = AVURLAsset(url: originalVideoURL2)
let mixComposition = AVMutableComposition()
guard let firstTrack = mixComposition.addMutableTrack(withMediaType: .video, preferredTrackID: Int32(kCMPersistentTrackID_Invalid)) else { return }
let timeRange1 = CMTimeRangeMake(start: .zero, duration: firstAsset.duration)
do {
try firstTrack.insertTimeRange(timeRange1, of: firstAsset.tracks(withMediaType: .video)[0], at: .zero)
} catch {
return
}
guard let secondTrack = mixComposition.addMutableTrack(withMediaType: .video, preferredTrackID: Int32(kCMPersistentTrackID_Invalid)) else { return }
let timeRange2 = CMTimeRangeMake(start: .zero, duration: secondAsset.duration)
do {
try secondTrack.insertTimeRange(timeRange2, of: secondAsset.tracks(withMediaType: .video)[0], at: .zero)
} catch {
return
}
let mainInstruction = AVMutableVideoCompositionInstruction()
mainInstruction.timeRange = CMTimeRangeMake(start: .zero, duration: CMTimeMaximum(firstAsset.duration, secondAsset.duration))
var track: AVAssetTrack!
track = firstAsset.tracks(withMediaType: .video).first
let firstSize = track.naturalSize.applying(track.preferredTransform)
track = secondAsset.tracks(withMediaType: .video).first
let secondSize = track.naturalSize.applying(track.preferredTransform)
// debugging
print("firstSize:", firstSize)
print("secondSize:", secondSize)
let renderSize = CGSize(width: 640, height: 480)
var scale: CGAffineTransform!
var move: CGAffineTransform!
let firstLayerInstruction = AVMutableVideoCompositionLayerInstruction(assetTrack: firstTrack)
scale = .identity
move = .identity
if (firstSize.width < 0) {
scale = CGAffineTransform(rotationAngle: .pi)
}
scale = scale.scaledBy(x: abs(renderSize.width / 2.0 / firstSize.width), y: abs(renderSize.height / firstSize.height))
move = CGAffineTransform(translationX: 0, y: 0)
if (firstSize.width < 0) {
move = CGAffineTransform(translationX: renderSize.width / 2.0, y: renderSize.height)
}
firstLayerInstruction.setTransform(scale.concatenating(move), at: .zero)
let secondLayerInstruction = AVMutableVideoCompositionLayerInstruction(assetTrack: secondTrack)
scale = .identity
move = .identity
if (secondSize.width < 0) {
scale = CGAffineTransform(rotationAngle: .pi)
}
scale = scale.scaledBy(x: abs(renderSize.width / 2.0 / secondSize.width), y: abs(renderSize.height / secondSize.height))
move = CGAffineTransform(translationX: renderSize.width / 2.0, y: 0)
if (secondSize.width < 0) {
move = CGAffineTransform(translationX: renderSize.width, y: renderSize.height)
}
secondLayerInstruction.setTransform(scale.concatenating(move), at: .zero)
mainInstruction.layerInstructions = [firstLayerInstruction, secondLayerInstruction]
let mainCompositionInst = AVMutableVideoComposition()
mainCompositionInst.instructions = [mainInstruction]
mainCompositionInst.frameDuration = CMTime(value: 1, timescale: 30)
mainCompositionInst.renderSize = renderSize
let newPlayerItem = AVPlayerItem(asset: mixComposition)
newPlayerItem.videoComposition = mainCompositionInst
let player = AVPlayer(playerItem: newPlayerItem)
let playerLayer = AVPlayerLayer(player: player)
playerLayer.frame = view.bounds
view.layer.addSublayer(playerLayer)
player.seek(to: .zero)
player.play()
// video export code goes here...
}
}
對於前置/后置攝像頭、鏡像等,preferredTransforms 也可能不同。但我會讓你自己解決。
編輯
示例項目位於: https://github.com/DonMag/VideoTest
制作(使用兩個720 x 1280
視頻剪輯):
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