PlaybackClock.kt

src/jvmMain/kotlin/afield/graphics/texture/video/PlaybackClock.kt · 81 lines

Defines PlaybackClock, the time source VideoTexture reads to choose a frame, with two implementations: SystemClock (a monotonic clock with play, pause and seek) and AudioClock (time taken from an AudioPlayer).

package afield.graphics.texture.video

interface PlaybackClock

Time source consumed by VideoTexture when selecting the frame for the current update.

interface PlaybackClock {

fun getCurrentTime(): Double

Get the current playback time in seconds. @return Current time in seconds from the start of playback

fun isPlaying(): Boolean

Check if the clock is currently active/playing. @return true if the clock is running

class SystemClock : PlaybackClock

Monotonic process clock with explicit play, pause, seek, and reset state.

VideoTexture creates this implementation internally when no external PlaybackClock is given.

class SystemClock : PlaybackClock {
    private var startTime: Long = 0
    private var pausedTime: Double = 0.0
    private var isActive: Boolean = false

override fun getCurrentTime(): Double

    override fun getCurrentTime(): Double {
        if (!isActive) return pausedTime

        val elapsed = (System.nanoTime() - startTime) / 1_000_000_000.0
        return pausedTime + elapsed
    }

override fun isPlaying(): Boolean = isActive

fun play()

    fun play() {
        if (!isActive) {
            startTime = System.nanoTime()
            isActive = true
        }
    }

fun pause()

    fun pause() {
        if (isActive) {
            pausedTime = getCurrentTime()
            isActive = false
        }
    }

fun seek(timestamp: Double)

    fun seek(timestamp: Double) {
        pausedTime = timestamp
        if (isActive) {
            startTime = System.nanoTime()
        }
    }

fun reset()

    fun reset() {
        startTime = System.nanoTime()
        pausedTime = 0.0
        isActive = false
    }
}

class AudioClock(private val audioPlayer: AudioPlayer) : PlaybackClock

Delegates time and playing state to AudioPlayer's processed-sample and OpenAL-offset clock.

override fun getCurrentTime(): Double

    override fun getCurrentTime(): Double {
        return audioPlayer.getCurrentTime()
    }

override fun isPlaying(): Boolean

    override fun isPlaying(): Boolean {
        return audioPlayer.isCurrentlyPlaying()
    }
}