Android Canvas.drawText()的双十进制数字未正确呈现

Question

当我试图呈现一些带有数字的文本时，会出现奇怪的行为。问题可能与线程有关。我的问题是，当我用Canvas.drawText((绘制时，数字总是显示为0.0，但如果我用Log.d((绘制，数字不是0.0，而是大约60。

这是我的代码：

GameView:

class GameView(
context: Context?,
attrs: AttributeSet
) : SurfaceView(context, attrs), SurfaceHolder.Callback {
private var gameLoop: GameLoop = GameLoop(this, holder)
private val paint: Paint = Paint()
init {
holder.addCallback(this)
isFocusable = true
}
fun update() {
// TODO: update game state
}
override fun surfaceCreated(surfaceHolder: SurfaceHolder) {
gameLoop.startLoop()
}
override fun surfaceChanged(surfaceHolder: SurfaceHolder, p1: Int, p2: Int, p3: Int) {
// do nothing
}
override fun surfaceDestroyed(surfaceHolder: SurfaceHolder) {
gameLoop.stopLoop()
}
override fun draw(drawCanvas: Canvas) {
super.draw(drawCanvas)
drawInfo(drawCanvas)
}
private fun drawInfo(canvas: Canvas) {
val averageUps = gameLoop.getAverageUps()
val averageFps = gameLoop.getAverageFps()
val color = ContextCompat.getColor(context, DEBUG_TEXT_COLOR)
paint.color = color
paint.textSize = DEBUG_TEXT_SIZE
canvas.drawText("UPS: $averageUps", 40f, DEBUG_TEXT_SIZE, paint)
canvas.drawText("FPS: $averageFps", 40f, DEBUG_TEXT_SIZE*2 + 10f, paint)
}
companion object {
const val DEBUG_TEXT_SIZE = 40f
const val DEBUG_TEXT_COLOR = R.color.light_blue_A200
}
}

GameLoop:

class GameLoop(
private val gameView: GameView,
private val surfaceHolder: SurfaceHolder
) : Thread() {
private var isRunning: Boolean = false
private var averageUps: Double = 0.0
private var averageFps: Double = 0.0
fun getAverageUps(): Double {
return averageUps
}
fun getAverageFps(): Double {
return averageFps
}
fun startLoop() {
isRunning = true
start()
}
override fun run() {
super.run()
var updateCount = 0
var frameCount = 0
var startTime = 0L
var elapsedTime = 0L
var sleepTime = 0L
var canvas: Canvas? = null
startTime = System.currentTimeMillis()
while (isRunning) {
try {
canvas = surfaceHolder.lockCanvas()
synchronized(canvas) {
gameView.update()
updateCount++
gameView.draw(canvas)
}
} catch (iae: IllegalArgumentException) {
iae.printStackTrace()
} finally {
if (canvas != null) {
surfaceHolder.unlockCanvasAndPost(canvas)
frameCount++
}
}
elapsedTime = System.currentTimeMillis() - startTime
sleepTime = (updateCount*UPS_PERIOD - elapsedTime)
if (sleepTime > 0) {
try {
sleep(sleepTime)
} catch (ie: InterruptedException) {
ie.printStackTrace()
}
}
while (sleepTime < 0 && updateCount < MAX_UPS-1) {
gameView.update()
updateCount++
elapsedTime = System.currentTimeMillis() - startTime
sleepTime = (updateCount*UPS_PERIOD - elapsedTime)
}
elapsedTime = System.currentTimeMillis() - startTime
if (elapsedTime >= 1000.0) {
averageUps = updateCount.toDouble() / (elapsedTime/1000.0)
averageFps = frameCount.toDouble() / (elapsedTime/1000.0)
updateCount = 0
frameCount = 0
startTime = System.currentTimeMillis()
}
}
}
fun stopLoop() {
// TODO: finish me...
}
companion object {
private const val MAX_UPS: Long = 60
const val UPS_PERIOD: Long = 1000/MAX_UPS
}
}

问题出现在GameView.drawInfo(canvas：canvas(中。输出总是"；UPS:0.0 FPS:0.0〃；但当我注销averageUps和averageFps时，它们都在~60左右。

我希望你能帮我解决这个问题：-(

Answer 1

要回答我自己的问题：问题出现在包含GameView的活动中。我在xml中有GameView。当我手动实例化GameView并将其与setContentView(GameView(一起放置时，所有渲染都开始工作。