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MacOS swift marquee scrolling text view
import Cocoa
open class ScrollingTextView: NSView {
// MARK: - Open variables
/// Text to scroll
open var text: NSString?
/// Font for scrolling text
open var font: NSFont?
/// Scrolling text color
open var textColor: NSColor = .headerTextColor
/// Determines if the text should be delayed before starting scroll
open var isDelayed: Bool = true
/// Spacing between the tail and head of the scrolling text
open var spacing: CGFloat = 20
/// Length of the scrolling text view
open var length: CGFloat = 0 {
didSet {
updateTraits()
}
}
/// Amount of time the text is delayed before scrolling
open var delay: TimeInterval = 2 {
didSet {
updateTraits()
}
}
/// Speed at which the text scrolls. This number is divided by 100.
open var speed: Double = 4 {
didSet {
updateTraits()
}
}
// MARK: - Private variables
private var timer: Timer?
private var point = NSPoint(x: 0, y: 0)
private var timeInterval: TimeInterval?
private(set) var stringSize = NSSize(width: 0, height: 0) {
didSet {
point.x = 0
}
}
private var timerSpeed: Double? {
return speed / 100
}
private lazy var textFontAttributes: [NSAttributedString.Key: Any] = {
return [NSAttributedString.Key.font: font ?? NSFont.systemFont(ofSize: 14)]
}()
// MARK: - Open functions
/**
Sets up the scrolling text view
- Parameters:
- string: The string that will be used as the text in the view
*/
open func setup(string: String) {
text = string as NSString
stringSize = text?.size(withAttributes: textFontAttributes) ?? NSSize(width: 0, height: 0)
setNeedsDisplay(NSRect(x: 0, y: 0, width: frame.width, height: frame.height))
updateTraits()
}
}
// MARK: - Private extension
private extension ScrollingTextView {
func setSpeed(newInterval: TimeInterval) {
clearTimer()
timeInterval = newInterval
guard let timeInterval = timeInterval else { return }
if timer == nil, timeInterval > 0.0, text != nil {
if #available(OSX 10.12, *) {
timer = Timer.scheduledTimer(timeInterval: newInterval, target: self, selector: #selector(update(_:)), userInfo: nil, repeats: true)
guard let timer = timer else { return }
RunLoop.main.add(timer, forMode: .common)
} else {
// Fallback on earlier versions
}
} else {
clearTimer()
point.x = 0
}
}
func updateTraits() {
clearTimer()
if stringSize.width > length {
guard let speed = timerSpeed else { return }
if #available(OSX 10.12, *), isDelayed {
timer = Timer.scheduledTimer(withTimeInterval: delay, repeats: false, block: { [weak self] timer in
self?.setSpeed(newInterval: speed)
})
} else {
setSpeed(newInterval: speed)
}
} else {
setSpeed(newInterval: 0.0)
}
}
func clearTimer() {
timer?.invalidate()
timer = nil
}
@objc
func update(_ sender: Timer) {
point.x = point.x - 1
setNeedsDisplay(NSRect(x: 0, y: 0, width: frame.width, height: frame.height))
}
}
// MARK: - Overrides
extension ScrollingTextView {
override open func draw(_ dirtyRect: NSRect) {
if point.x + stringSize.width < 0 {
point.x += stringSize.width + spacing
}
textFontAttributes[NSAttributedString.Key.foregroundColor] = textColor
text?.draw(at: point, withAttributes: textFontAttributes)
if point.x < 0 {
var otherPoint = point
otherPoint.x += stringSize.width + spacing
text?.draw(at: otherPoint, withAttributes: textFontAttributes)
}
}
override open func layout() {
super.layout()
point.y = (frame.height - stringSize.height) / 2
}
}
@NicholasBellucci
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Author

NicholasBellucci commented Nov 8, 2018

Big thanks to Dave for the starting point. https://stackoverflow.com/a/3233802/9493278.

Example

demo

@kartik-venugopal
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kartik-venugopal commented Jun 29, 2021

Nice work ! Code could use some polishing, but works well.

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