Swift 4 версия, которая использует вид документа в среде auto-layout .
Основано на статье Apple Синхронизация видов прокрутки с той разницей, что NSView.boundsDidChangeNotification временно игнорируется при просмотре клипа при синхронизации с другим видом прокрутки.
Для скрытия вертикального скроллера используется многоразовый тип InvisibleScroller.
Файл SynchronedScrollViewController.swift - Просмотр контроллеров с двумя видами прокрутки.
class SynchronedScrollViewController: ViewController {
private lazy var leftView = TestView().autolayoutView()
private lazy var rightView = TestView().autolayoutView()
private lazy var leftScrollView = ScrollView(horizontallyScrolledDocumentView: leftView).autolayoutView()
private lazy var rightScrollView = ScrollView(horizontallyScrolledDocumentView: rightView).autolayoutView()
override func setupUI() {
view.addSubviews(leftScrollView, rightScrollView)
leftView.backgroundColor = .red
rightView.backgroundColor = .blue
contentView.backgroundColor = .green
leftScrollView.verticalScroller = InvisibleScroller()
leftView.setIntrinsicContentSize(CGSize(intrinsicHeight: 720)) // Some fake height
rightView.setIntrinsicContentSize(CGSize(intrinsicHeight: 720)) // Some fake height
}
override func setupHandlers() {
(leftScrollView.contentView as? ClipView)?.onBoundsDidChange = { [weak self] in
print("\(Date().timeIntervalSinceReferenceDate) : Left scroll view changed")
self?.syncScrollViews(origin: $0)
}
(rightScrollView.contentView as? ClipView)?.onBoundsDidChange = { [weak self] in
print("\(Date().timeIntervalSinceReferenceDate) : Right scroll view changed.")
self?.syncScrollViews(origin: $0)
}
}
override func setupLayout() {
LayoutConstraint.pin(to: .vertically, leftScrollView, rightScrollView).activate()
LayoutConstraint.withFormat("|[*(==40)]-[*]|", leftScrollView, rightScrollView).activate()
}
private func syncScrollViews(origin: NSClipView) {
// See also:
// https://developer.apple.com/library/archive/documentation/Cocoa/Conceptual/NSScrollViewGuide/Articles/SynchroScroll.html
let changedBoundsOrigin = origin.documentVisibleRect.origin
let targetScrollView = leftScrollView.contentView == origin ? rightScrollView : leftScrollView
let curOffset = targetScrollView.contentView.bounds.origin
var newOffset = curOffset
newOffset.y = changedBoundsOrigin.y
if curOffset != changedBoundsOrigin {
(targetScrollView.contentView as? ClipView)?.scroll(newOffset, shouldNotifyBoundsChange: false)
targetScrollView.reflectScrolledClipView(targetScrollView.contentView)
}
}
}
Файл: TestView.swift - Тестовый просмотр. Рисует линию каждые 20 очков.
class TestView: View {
override init() {
super.init()
setIsFlipped(true)
}
override func setupLayout() {
needsDisplay = true
}
required init?(coder decoder: NSCoder) {
fatalError()
}
override func draw(_ dirtyRect: NSRect) {
super.draw(dirtyRect)
guard let context = NSGraphicsContext.current else {
return
}
context.saveGraphicsState()
let cgContext = context.cgContext
cgContext.setStrokeColor(NSColor.white.cgColor)
for x in stride(from: CGFloat(20), through: bounds.height, by: 20) {
cgContext.addLines(between: [CGPoint(x: 0, y: x), CGPoint(x: bounds.width, y: x)])
NSString(string: "\(Int(x))").draw(at: CGPoint(x: 0, y: x), withAttributes: nil)
}
cgContext.strokePath()
context.restoreGraphicsState()
}
}
Файл: NSScrollView.swift - Многоразовое расширение.
extension NSScrollView {
public convenience init(documentView view: NSView) {
let frame = CGRect(dimension: 10) // Some dummy non zero value
self.init(frame: frame)
let clipView = ClipView(frame: frame)
clipView.documentView = view
clipView.autoresizingMask = [.height, .width]
contentView = clipView
view.frame = frame
view.translatesAutoresizingMaskIntoConstraints = true
view.autoresizingMask = [.width, .height]
}
public convenience init(horizontallyScrolledDocumentView view: NSView) {
self.init(documentView: view)
contentView.setIsFlipped(true)
view.translatesAutoresizingMaskIntoConstraints = false
LayoutConstraint.pin(in: contentView, to: .horizontally, view).activate()
view.topAnchor.constraint(equalTo: contentView.topAnchor).activate()
hasVerticalScroller = true // Without this scroll might not work properly. Seems Apple bug.
}
}
Файл: InvisibleScroller.swift - Многоразовый невидимый скроллер.
// Disabling scroll view indicators.
// See: /6849417/skryt-skrollery-ostaviv-prokrutku-vklychennoi-v-nsscrollview
public class InvisibleScroller: Scroller {
public override class var isCompatibleWithOverlayScrollers: Bool {
return true
}
public override class func scrollerWidth(for controlSize: NSControl.ControlSize, scrollerStyle: NSScroller.Style) -> CGFloat {
return CGFloat.leastNormalMagnitude // Dimension of scroller is equal to `FLT_MIN`
}
public override func setupUI() {
// Below assignments not really needed, but why not.
scrollerStyle = .overlay
alphaValue = 0
}
}
Файл: ClipView.swift - Индивидуальный подкласс NSClipView.
open class ClipView: NSClipView {
public var onBoundsDidChange: ((NSClipView) -> Void)? {
didSet {
setupBoundsChangeObserver()
}
}
private var boundsChangeObserver: NotificationObserver?
private var mIsFlipped: Bool?
open override var isFlipped: Bool {
return mIsFlipped ?? super.isFlipped
}
// MARK: -
public func setIsFlipped(_ value: Bool?) {
mIsFlipped = value
}
open func scroll(_ point: NSPoint, shouldNotifyBoundsChange: Bool) {
if shouldNotifyBoundsChange {
scroll(to: point)
} else {
boundsChangeObserver?.isActive = false
scroll(to: point)
boundsChangeObserver?.isActive = true
}
}
// MARK: - Private
private func setupBoundsChangeObserver() {
postsBoundsChangedNotifications = onBoundsDidChange != nil
boundsChangeObserver = nil
if postsBoundsChangedNotifications {
boundsChangeObserver = NotificationObserver(name: NSView.boundsDidChangeNotification, object: self) { [weak self] _ in
guard let this = self else { return }
self?.onBoundsDidChange?(this)
}
}
}
}
Файл: NotificationObserver.swift - Многоразовый наблюдатель уведомлений.
public class NotificationObserver: NSObject {
public typealias Handler = ((Foundation.Notification) -> Void)
private var notificationObserver: NSObjectProtocol!
private let notificationObject: Any?
public var handler: Handler?
public var isActive: Bool = true
public private(set) var notificationName: NSNotification.Name
public init(name: NSNotification.Name, object: Any? = nil, queue: OperationQueue = .main, handler: Handler? = nil) {
notificationName = name
notificationObject = object
self.handler = handler
super.init()
notificationObserver = NotificationCenter.default.addObserver(forName: name, object: object, queue: queue) { [weak self] in
guard let this = self else { return }
if this.isActive {
self?.handler?($0)
}
}
}
deinit {
NotificationCenter.default.removeObserver(notificationObserver, name: notificationName, object: notificationObject)
}
}
Результат:
