Call the listeners of PropertyKind.Renderer on render API fallback (#1033)

skiko/src/awtMain/kotlin/org/jetbrains/skiko/Actuals.awt.kt

@@ -8,7 +8,6 @@ import java.awt.datatransfer.DataFlavor
 import java.awt.datatransfer.StringSelection
 import java.awt.datatransfer.UnsupportedFlavorException
 import java.io.IOException
-import java.net.MalformedURLException
 import java.net.URI
 import java.net.URL
 import javax.swing.UIManager
@@ -16,13 +15,8 @@ import javax.swing.UIManager
 actual fun setSystemLookAndFeel() = UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName())
 
 internal actual fun makeDefaultRenderFactory(): RenderFactory =
-    object : RenderFactory {
-        override fun createRedrawer(
-            layer: SkiaLayer,
-            renderApi: GraphicsApi,
-            analytics: SkiaLayerAnalytics,
-            properties: SkiaLayerProperties
-        ): Redrawer = when (hostOs) {
+    RenderFactory { layer, renderApi, analytics, properties ->
+        when (hostOs) {
             OS.MacOS -> when (renderApi) {
                 GraphicsApi.SOFTWARE_COMPAT, GraphicsApi.SOFTWARE_FAST -> SoftwareRedrawer(layer, analytics, properties)
                 else -> MetalRedrawer(layer, analytics, properties)

skiko/src/awtMain/kotlin/org/jetbrains/skiko/SkiaLayer.awt.kt

@@ -284,22 +284,22 @@ actual open class SkiaLayer internal constructor(
     @Volatile
     private var isDisposed = false
 
-    private val redrawerManager = RedrawerManager<Redrawer>(properties.renderApi) { renderApi, oldRedrawer ->
-        oldRedrawer?.dispose()
-        val newRedrawer = renderFactory.createRedrawer(this, renderApi, analytics, properties)
-        newRedrawer.syncBounds()
-        newRedrawer
-    }
-
-    internal val redrawer: Redrawer?
-        get() = redrawerManager.redrawer
-
-    actual var renderApi: GraphicsApi
-        get() = redrawerManager.renderApi
-        set(value) {
-            redrawerManager.forceRenderApi(value)
+    private val redrawerManager = RedrawerManager<Redrawer>(
+        defaultRenderApi = properties.renderApi,
+        redrawerFactory = { renderApi, oldRedrawer ->
+            oldRedrawer?.dispose()
+            renderFactory.createRedrawer(this, renderApi, analytics, properties).also {
+                it.syncBounds()
+            }
+        },
+        onRenderApiChanged = {
             notifyChange(PropertyKind.Renderer)
         }
+    )
+
+    internal val redrawer: Redrawer? by redrawerManager::redrawer
+
+    actual var renderApi: GraphicsApi by redrawerManager::renderApi
 
     val renderInfo: String
         get() = if (redrawer == null)
@@ -320,15 +320,15 @@ actual open class SkiaLayer internal constructor(
         isInited = true
     }
 
-    private val stateHandlers =
+    private val stateChangeListeners =
         mutableMapOf<PropertyKind, MutableList<(SkiaLayer) -> Unit>>()
 
     fun onStateChanged(kind: PropertyKind, handler: (SkiaLayer) -> Unit) {
-        stateHandlers.getOrPut(kind, { mutableListOf() }) += handler
+        stateChangeListeners.getOrPut(kind, ::mutableListOf) += handler
     }
 
     private fun notifyChange(kind: PropertyKind) {
-        stateHandlers.get(kind)?.let { handlers ->
+        stateChangeListeners[kind]?.let { handlers ->
             handlers.forEach { it(this) }
         }
     }
@@ -583,7 +583,7 @@ actual open class SkiaLayer internal constructor(
         }
     }
 
-    actual internal fun draw(canvas: Canvas) {
+    internal actual fun draw(canvas: Canvas) {
         check(!isDisposed) { "SkiaLayer is disposed" }
         lockPicture {
             canvas.drawPicture(it.instance)

skiko/src/awtMain/kotlin/org/jetbrains/skiko/redrawer/RedrawerManager.kt

@@ -7,17 +7,19 @@ import org.jetbrains.skiko.SkikoProperties
 
 internal class RedrawerManager<R>(
     defaultRenderApi: GraphicsApi,
-    private val redrawerFactory: (renderApi: GraphicsApi, oldRedrawer: R?) -> R
+    private val redrawerFactory: (renderApi: GraphicsApi, oldRedrawer: R?) -> R,
+    private val onRenderApiChanged: ((GraphicsApi) -> Unit)? = null
 ) {
-    private var _redrawer: R? = null
     private val fallbackRenderApiQueue = SkikoProperties.fallbackRenderApiQueue(defaultRenderApi).toMutableList()
-    private var _renderApi = fallbackRenderApiQueue[0]
 
-    val redrawer: R?
-        get() = _redrawer
+    var redrawer: R? = null
+        private set
 
-    val renderApi: GraphicsApi
-        get() = _renderApi
+    var renderApi: GraphicsApi = fallbackRenderApiQueue[0]
+        set(value) {
+            field = value
+            onRenderApiChanged?.invoke(value)
+        }
 
     fun findNextWorkingRenderApi(recreation: Boolean = false) {
         if (recreation) {
@@ -27,10 +29,10 @@ internal class RedrawerManager<R>(
         do {
             thrown = false
             try {
-                _renderApi = fallbackRenderApiQueue.removeAt(0)
-                _redrawer = redrawerFactory(_renderApi, redrawer)
+                renderApi = fallbackRenderApiQueue.removeAt(0)
+                redrawer = redrawerFactory(renderApi, redrawer)
             } catch (e: RenderException) {
-                _redrawer = null
+                redrawer = null
                 Logger.warn(e) { "Fallback to next API" }
                 thrown = true
             }
@@ -41,11 +43,7 @@ internal class RedrawerManager<R>(
         }
     }
 
-    fun forceRenderApi(renderApi: GraphicsApi) {
-        _renderApi = renderApi
-    }
-
     fun dispose() {
-        _redrawer = null
+        redrawer = null
     }
 }
\ No newline at end of file

skiko/src/awtMain/kotlin/org/jetbrains/skiko/swing/SkiaSwingLayer.kt

@@ -4,11 +4,11 @@ import org.jetbrains.skia.Canvas
 import org.jetbrains.skiko.*
 import org.jetbrains.skiko.redrawer.RedrawerManager
 import java.awt.Component
+import java.awt.Graphics
 import java.awt.Graphics2D
 import java.awt.GraphicsConfiguration
 import javax.accessibility.Accessible
 import javax.accessibility.AccessibleContext
-import javax.swing.JComponent
 import javax.swing.JPanel
 import javax.swing.SwingUtilities.isEventDispatchThread
 
@@ -65,10 +65,13 @@ open class SkiaSwingLayer(
             get() = this@SkiaSwingLayer.properties.adapterPriority
     }
 
-    private val redrawerManager = RedrawerManager<SwingRedrawer>(properties.renderApi) { renderApi, oldRedrawer ->
-        oldRedrawer?.dispose()
-        createSwingRedrawer(swingLayerProperties, renderDelegateWithClipping, renderApi, analytics)
-    }
+    private val redrawerManager = RedrawerManager<SwingRedrawer>(
+        properties.renderApi,
+        redrawerFactory = { renderApi, oldRedrawer ->
+            oldRedrawer?.dispose()
+            createSwingRedrawer(swingLayerProperties, renderDelegateWithClipping, renderApi, analytics)
+        }
+    )
 
     private val redrawer: SwingRedrawer?
         get() = redrawerManager.redrawer
@@ -109,7 +112,7 @@ open class SkiaSwingLayer(
         }
     }
 
-    override fun paint(g: java.awt.Graphics) {
+    override fun paint(g: Graphics) {
         try {
             redrawer?.redraw(g as Graphics2D)
         } catch (e: RenderException) {

skiko/src/awtTest/kotlin/org/jetbrains/skiko/SkiaLayerTest.kt

@@ -541,63 +541,41 @@ class SkiaLayerTest {
         }
     }
 
+    private abstract class BaseTestRedrawer: Redrawer {
+        override fun dispose() = Unit
+        override fun needRedraw() = Unit
+        override fun redrawImmediately() = Unit
+        override val renderInfo: String
+            get() = ""
+    }
+
     @Test(timeout = 60000)
     fun `fallback to software renderer, fail on init context`() = uiTest {
-        testFallbackToSoftware(
-            object : RenderFactory {
-                override fun createRedrawer(
-                    layer: SkiaLayer,
-                    renderApi: GraphicsApi,
-                    analytics: SkiaLayerAnalytics,
-                    properties: SkiaLayerProperties
-                ) = object : Redrawer {
-                    private val contextHandler = object : JvmContextHandler(layer) {
-                        override fun initContext() = false
-                        override fun initCanvas() = Unit
-                    }
-
-                    override fun dispose() = Unit
-                    override fun needRedraw() = Unit
-                    override fun redrawImmediately() = layer.inDrawScope(contextHandler::draw)
-                    override val renderInfo = ""
+        testFallbackToSoftware { layer, _, _, _ ->
+            object : BaseTestRedrawer() {
+                private val contextHandler = object : JvmContextHandler(layer) {
+                    override fun initContext() = false
+                    override fun initCanvas() = Unit
                 }
+                override fun redrawImmediately() = layer.inDrawScope(contextHandler::draw)
             }
-        )
+        }
     }
 
     @Test(timeout = 60000)
     fun `fallback to software renderer, fail on create redrawer`() = uiTest {
-        testFallbackToSoftware(
-            object : RenderFactory {
-                override fun createRedrawer(
-                    layer: SkiaLayer,
-                    renderApi: GraphicsApi,
-                    analytics: SkiaLayerAnalytics,
-                    properties: SkiaLayerProperties
-                ) = throw RenderException()
-            }
-        )
+        testFallbackToSoftware { _, _, _, _ -> throw RenderException() }
     }
 
     @Test(timeout = 60000)
     fun `fallback to software renderer, fail on draw`() = uiTest {
-        testFallbackToSoftware(
-            object : RenderFactory {
-                override fun createRedrawer(
-                    layer: SkiaLayer,
-                    renderApi: GraphicsApi,
-                    analytics: SkiaLayerAnalytics,
-                    properties: SkiaLayerProperties
-                ) = object : Redrawer {
-                    override fun dispose() = Unit
-                    override fun needRedraw() = Unit
-                    override fun redrawImmediately() = layer.inDrawScope {
-                        throw RenderException()
-                    }
-                    override val renderInfo = ""
+        testFallbackToSoftware { layer, _, _, _ ->
+            object : BaseTestRedrawer() {
+                override fun redrawImmediately() = layer.inDrawScope {
+                    throw RenderException()
                 }
             }
-        )
+        }
     }
 
     private suspend fun UiTestScope.testFallbackToSoftware(nonSoftwareRenderFactory: RenderFactory) {
@@ -644,6 +622,35 @@ class SkiaLayerTest {
         }
     }
 
+    @Test(timeout = 60000)
+    fun `renderApi change callback is invoked on fallback`() = uiTest {
+        val window = UiTestWindow(
+            renderFactory = OverrideNonSoftwareRenderFactory { layer, _, _, _ ->
+                object : BaseTestRedrawer() {
+                    override fun redrawImmediately() = layer.inDrawScope {
+                        throw RenderException()
+                    }
+                }
+            }
+        )
+        try {
+            var rendererChangedCallbackInvoked = false
+            window.layer.onStateChanged(SkiaLayer.PropertyKind.Renderer) {
+                rendererChangedCallbackInvoked = true
+            }
+            window.setLocation(200, 200)
+            window.setSize(400, 200)
+            window.isVisible = true
+
+            delay(1000)
+
+            assertEquals(GraphicsApi.SOFTWARE_COMPAT, window.layer.renderApi)
+            assertTrue(rendererChangedCallbackInvoked)
+        } finally {
+            window.close()
+        }
+    }
+
     @Test(timeout = 20000)
     fun `render continuously empty content without vsync`() = uiTest {
         val targetDrawCount = 500
@@ -981,21 +988,25 @@ class SkiaLayerTest {
             }
             contentPane.add(layer)
         }
-        window.size = Dimension(400, 400)
-        window.isVisible = true
+        try {
+            window.size = Dimension(400, 400)
+            window.isVisible = true
 
-        repeat(20) {
-            window.location = window.location.let {
-                java.awt.Point(it.x + 10, it.y + 10)
+            repeat(20) {
+                window.location = window.location.let {
+                    java.awt.Point(it.x + 10, it.y + 10)
+                }
+                delay(50)
             }
-            delay(50)
-        }
 
-        // Ideally, layoutCount would be just 1, but Swing appears to call layout one extra time, so it ends up being 2.
-        // Compare to 3 just to avoid a false-failure if there's another layout for whatever reason.
-        // What we're interested to validate is that there's no layout occurring on every window move.
-        assert(layoutCount <= 3) {
-            "Layout count: $layoutCount"
+            // Ideally, layoutCount would be just 1, but Swing appears to call layout one extra time, so it ends up being 2.
+            // Compare to 3 just to avoid a false-failure if there's another layout for whatever reason.
+            // What we're interested to validate is that there's no layout occurring on every window move.
+            assert(layoutCount <= 3) {
+                "Layout count: $layoutCount"
+            }
+        } finally {
+            window.dispose()
         }
     }
 

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

@@ -2,7 +2,7 @@ package org.jetbrains.skiko
 
 import org.jetbrains.skiko.redrawer.*
 
-internal interface RenderFactory {
+internal fun interface RenderFactory {
     fun createRedrawer(
         layer: SkiaLayer,
         renderApi: GraphicsApi,