Vsync: review feedback

samples/SkijaInjectSample/build.gradle

@@ -61,7 +61,7 @@ run {
 test {
     systemProperty("skiko.test.screenshots.dir", new File(project.projectDir, "src/test/screenshots").absolutePath)
 
-    // Tests should be determined, so disable scaling.
+    // Tests should be deterministic, so disable scaling.
     // On MacOs we need the actual scale, otherwise we will have aliased screenshots because of scaling.
     if (System.getProperty("os.name") != "Mac OS X") {
         systemProperty("sun.java2d.dpiaware", "false")

samples/SkijaInjectSample/src/main/kotlin/SkijaInjectSample/SwingSkia.kt

@@ -7,10 +7,7 @@ import java.awt.event.ComponentAdapter
 import java.awt.event.ComponentEvent
 import java.awt.event.MouseEvent
 import java.awt.event.MouseMotionAdapter
-import javax.swing.JButton
-import javax.swing.JFrame
-import javax.swing.JPanel
-import javax.swing.WindowConstants
+import javax.swing.*
 
 
 fun Button(text: String): JButton {
@@ -19,7 +16,7 @@ fun Button(text: String): JButton {
     return btn
 }
 
-fun SwingSkia() {
+fun SwingSkia() = SwingUtilities.invokeLater {
 
     val window = JFrame()
     window.defaultCloseOperation = WindowConstants.EXIT_ON_CLOSE

samples/SkijaInjectSample/src/test/kotlin/org/jetbrains/skiko/ScreenshotTestRule.kt

@@ -8,7 +8,10 @@ import java.awt.Robot
 import java.io.File
 import javax.imageio.ImageIO
 
-// TODO macOs has wrong colors. Only white, black, red and green are correct
+// WARNING!!!
+// macOS has wrong colors ([128, 128, 128] isn't [128, 128, 128] on screenshot). Only white, black, red and green are correct.
+// So use only these color for cross-platform screenshots tests.
+// TODO fix colors on macOS
 class ScreenshotTestRule(private val robot: Robot) : TestRule {
     private lateinit var testIdentifier: String
     private val screenshotsDir = File(System.getProperty("skiko.test.screenshots.dir")!!)

skiko/src/jvmMain/kotlin/org/jetbrains/skiko/FPSCounter.kt

@@ -15,9 +15,8 @@ internal class FPSCounter(
      * [value] 0.0 - min, 1.0 - max, 0.5 - median
      */
     private fun MutableList<Double>.quantile(value: Double) : Double {
-        sort()
         val index = (value * (size - 1)).toInt()
-        return this[index]
+        return sorted()[index]
     }
 
     fun tick() {

skiko/src/jvmMain/kotlin/org/jetbrains/skiko/HardwareLayer.kt

@@ -26,7 +26,7 @@ abstract class HardwareLayer : Canvas() {
 
     private fun checkIsShowing() {
         if (!isInit && isShowing) {
-            _contentScale = platformOperations.getDpiScale(this)
+            _contentScale = getDpiScale()
             init()
             isInit = true
         }
@@ -38,13 +38,19 @@ abstract class HardwareLayer : Canvas() {
     protected open fun contentScaleChanged() = Unit
 
     override fun paint(g: Graphics) {
-        val contentScale = platformOperations.getDpiScale(this)
+        val contentScale = getDpiScale()
         if (contentScale != _contentScale) {
             _contentScale = contentScale
             contentScaleChanged()
         }
     }
 
+    private fun getDpiScale(): Float {
+        val scale = platformOperations.getDpiScale(this)
+        check(scale > 0) { "HardwareLayer.contentScale isn't positive: $contentScale"}
+        return scale
+    }
+
     // Should be called in Swing thread
     internal abstract suspend fun update(nanoTime: Long)
 

skiko/src/jvmMain/kotlin/org/jetbrains/skiko/SkiaLayer.kt

@@ -42,6 +42,7 @@ open class SkiaLayer : HardwareLayer() {
     private val pictureLock = Any()
 
     override fun init() {
+        super.init()
         redrawer = platformOperations.createHardwareRedrawer(this)
         redrawer?.syncSize()
         needRedraw()

skiko/src/jvmMain/kotlin/org/jetbrains/skiko/redrawer/MacOsRedrawer.kt

@@ -18,9 +18,9 @@ internal class MacOsRedrawer(
         override fun draw() = layer.draw()
     }
 
-    // use separate layer for vsync, because with single layer we cannot asynchronously update layer
+    // use a separate layer for vsync, because with single layer we cannot asynchronously update layer
     // `update` is suspend, and runBlocking(Dispatchers.Swing) causes dead lock with AppKit Thread.
-    // AWT has internal method to avoid dead locks but it is internal (sun.lwawt.macosx.LWCToolkit.invokeAndWait)
+    // AWT has a method to avoid dead locks but it is internal (sun.lwawt.macosx.LWCToolkit.invokeAndWait)
     private val vsyncLayer = object : AWTGLLayer(containerLayerPtr) {
         @Volatile
         private var needDraw: CompletableDeferred<Unit>? = null