Move canvas preparation from ContextHandler.draw to SkiaLayer.awt.update() (#1178)

skiko/src/androidMain/kotlin/org/jetbrains/skiko/Actuals.android.kt

@@ -4,6 +4,7 @@ import android.content.*
 import android.content.res.Configuration
 import android.view.View
 import org.jetbrains.skiko.redrawer.Redrawer
+import org.jetbrains.skiko.redrawer.defaultIsTransparentBackgroundSupported
 
 actual fun setSystemLookAndFeel(): Unit = TODO()
 
@@ -15,6 +16,7 @@ internal class AndroidOpenGLRedrawer(
     override fun needRender(canUpdateImmediately: Boolean) = TODO()
     override fun renderImmediately() = TODO()
     override fun update(nanoTime: Long) = TODO()
+    override fun isTransparentBackgroundSupported() = defaultIsTransparentBackgroundSupported(layer)
 
     override val renderInfo: String get() = "Android renderer"
 }

skiko/src/androidMain/kotlin/org/jetbrains/skiko/SkiaLayer.android.kt

@@ -20,21 +20,6 @@ actual open class SkiaLayer {
             if (value) throw IllegalArgumentException("changing fullscreen is unsupported")
         }
 
-    actual var transparency: Boolean
-        get() = false
-        set(value) {
-            if (value) throw IllegalArgumentException("transparency unsupported")
-        }
-
-    /**
-     * The background color of the layer.
-     */
-    actual internal var backgroundColor: Int = Color.WHITE
-        set(value) {
-            field = value
-            needRender()
-        }
-
     actual var renderDelegate: SkikoRenderDelegate? = null
 
     actual fun attachTo(container: Any) {
@@ -81,8 +66,5 @@ actual open class SkiaLayer {
     actual val component: Any?
         get() = this.container
 
-    actual internal val cutoutRectangles: List<ClipRectangle>
-        get() = emptyList()
-
     internal actual fun draw(canvas: Canvas): Unit = TODO()
 }
\ No newline at end of file

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

@@ -194,18 +194,16 @@ actual open class SkiaLayer internal constructor(
     }
 
     private var _transparency: Boolean = false
-    actual var transparency: Boolean
+
+    /**
+     * Whether transparency is enabled.
+     */
+    var transparency: Boolean
         get() = _transparency
         set(value) {
             configureBackground(value, _background)
         }
 
-    internal actual var backgroundColor: Int
-        get() = background.rgb  // Will return an ancestor's non-null background after setBackground(null).
-        set(value) {
-            configureBackground(_transparency, Color(value, true))
-        }
-
     // This is needed because after setBackground(null), getBackground() will not return null, but an ancestor's
     // non-null background. But we need to preserve the null value when modifying `transparency`.
     private var _background: Color? = null
@@ -333,11 +331,11 @@ actual open class SkiaLayer internal constructor(
         jComponent.add(this)
     }
 
+    /**
+     * A list of rectangles to cut out from the rendered content; No content will be drawn inside them.
+     */
     val clipComponents = mutableListOf<ClipRectangle>()
 
-    internal actual val cutoutRectangles: List<ClipRectangle>
-        get() = clipComponents
-
     @Volatile
     private var isDisposed = false
 
@@ -603,13 +601,27 @@ actual open class SkiaLayer internal constructor(
         // If this approach will be changed, create an issue in https://youtrack.jetbrains.com/issues/CMP for changing it in
         // https://github.com/JetBrains/compose-multiplatform/blob/e4e2d329709cded91a09cc612d4defbce37aad96/benchmarks/multiplatform/benchmarks/src/commonMain/kotlin/MeasureComposable.kt#L151 as well
 
+        val contentScale = this.contentScale
         val pictureWidth = (backedLayer.width * contentScale).coerceAtLeast(0f)
         val pictureHeight = (backedLayer.height * contentScale).coerceAtLeast(0f)
         val intWidth = pictureWidth.toInt()
         val intHeight = pictureHeight.toInt()
 
         val pictureRecorder = pictureRecorder!!
-        val canvas = pictureRecorder.beginRecording(0f, 0f, pictureWidth, pictureHeight)
+        val canvas = pictureRecorder.beginRecording(0f, 0f, pictureWidth, pictureHeight).apply {
+            for (component in clipComponents) {
+                cutoutFromClip(component, contentScale)
+            }
+
+            val layerBg = background.rgb  // Will return an ancestor's non-null background after setBackground(null).
+            clear(
+                if (transparency && (redrawer?.isTransparentBackgroundSupported() == true)) {
+                    layerBg
+                } else {
+                    layerBg or 0xFF000000.toInt()
+                }
+            )
+        }
 
         try {
             isRendering = true

skiko/src/awtMain/kotlin/org/jetbrains/skiko/context/SoftwareContextHandler.kt

@@ -10,11 +10,6 @@ import java.awt.color.ColorSpace
 import java.awt.image.*
 
 internal class SoftwareContextHandler(layer: SkiaLayer) : ContextFreeContextHandler(layer) {
-    override fun isTransparentBackgroundSupported(): Boolean {
-        // TODO: why Software rendering has another transparency logic from the beginning
-        return hostOs == OS.MacOS
-    }
-
     val colorModel = ComponentColorModel(
         ColorSpace.getInstance(ColorSpace.CS_sRGB),
         true,

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

@@ -74,4 +74,6 @@ internal abstract class AWTRedrawer(
     protected fun checkDisposed() {
         check(!isDisposed) { "${this.javaClass.simpleName} is disposed" }
     }
+
+    override fun isTransparentBackgroundSupported() = defaultIsTransparentBackgroundSupported(layer)
 }
\ No newline at end of file

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

@@ -55,4 +55,9 @@ internal class SoftwareRedrawer(
             }
         }
     }
+
+    override fun isTransparentBackgroundSupported(): Boolean {
+        // TODO: why Software rendering has another transparency logic from the beginning
+        return hostOs == OS.MacOS
+    }
 }
\ No newline at end of file

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

 package org.jetbrains.skiko.swing
 
 import org.jetbrains.skiko.*
-import org.jetbrains.skiko.context.cutoutFromClip
 import org.jetbrains.skiko.redrawer.RedrawerManager
 import java.awt.Component
 import java.awt.Graphics
@@ -46,8 +45,8 @@ open class SkiaSwingLayer(
         val scale = graphicsConfiguration.defaultTransform.scaleX.toFloat()
         // clipping
         for (index in clipComponents.indices) {
-            val item = clipComponents[index]
-            canvas.cutoutFromClip(item, scale)
+            val component = clipComponents[index]
+            canvas.cutoutFromClip(component, scale)
         }
         renderDelegate.onRender(canvas, width, height, nanoTime)
     }

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

@@ -15,6 +15,7 @@ import org.jetbrains.skiko.context.JvmContextHandler
 import org.jetbrains.skiko.redrawer.MetalRedrawer
 import org.jetbrains.skiko.redrawer.MetalVSyncer
 import org.jetbrains.skiko.redrawer.Redrawer
+import org.jetbrains.skiko.redrawer.defaultIsTransparentBackgroundSupported
 import org.jetbrains.skiko.swing.SkiaSwingLayer
 import org.jetbrains.skiko.util.ScreenshotTestRule
 import org.jetbrains.skiko.util.UiTestScope
@@ -565,6 +566,7 @@ class SkiaLayerTest {
         override fun needRender(throttledToVsync: Boolean) = frameDispatcher.scheduleFrame()
         override fun renderImmediately() = Unit
         override fun update(nanoTime: Long) = layer.update(nanoTime)
+        override fun isTransparentBackgroundSupported() = defaultIsTransparentBackgroundSupported(layer)
 
         override val renderInfo: String
             get() = ""

skiko/src/awtTest/kotlin/org/jetbrains/skiko/util/UiTest.kt

@@ -15,7 +15,7 @@ internal fun uiTest(
     block: suspend UiTestScope.() -> Unit
 ) {
     assumeFalse(GraphicsEnvironment.isHeadless())
-    assumeTrue(System.getProperty("skiko.test.ui.enabled", "false") == "true")
+//    assumeTrue(System.getProperty("skiko.test.ui.enabled", "false") == "true")
 
     val renderApiProperty = System.getProperty("skiko.test.ui.renderApi", "all")
 

skiko/src/commonMain/kotlin/org/jetbrains/skia/Canvas.kt

@@ -1849,3 +1849,12 @@ private external fun _nRestore(ptr: NativePointer)
 
 @ExternalSymbolName("org_jetbrains_skia_Canvas__1nRestoreToCount")
 private external fun _nRestoreToCount(ptr: NativePointer, saveCount: Int)
+
+internal inline fun Canvas.runRestoringState(block: Canvas.() -> Unit) {
+    val restoreCount = save()
+    try {
+        block()
+    } finally {
+        restoreToCount(restoreCount)
+    }
+}
\ No newline at end of file

skiko/src/commonMain/kotlin/org/jetbrains/skiko/ClipRectangle.kt

 package org.jetbrains.skiko
 
+import org.jetbrains.skia.Canvas
+import org.jetbrains.skia.ClipMode
+
 /**
  * Rectangle used for clipping.
  */
@@ -18,4 +21,18 @@ internal fun ClipRectangle(x: Float, y: Float, width: Float, height: Float) = ob
     override val y: Float = y
     override val width: Float = width
     override val height: Float = height
-}
+}
\ No newline at end of file
+
+@Suppress("NOTHING_TO_INLINE")
+internal inline fun Canvas.cutoutFromClip(rect: ClipRectangle, scale: Float) {
+    val x = rect.x
+    val y = rect.y
+    clipRect(
+        left = x * scale,
+        top = y * scale,
+        right = (x + rect.width) * scale,
+        bottom = (y + rect.height) * scale,
+        mode = ClipMode.DIFFERENCE,
+        antiAlias = true
+    )
+}

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

@@ -28,26 +28,11 @@ expect open class SkiaLayer {
      */
     var fullscreen: Boolean
 
-    /**
-     * If transparency is enabled.
-     */
-    var transparency: Boolean
-
-    /**
-     * The color, in ARGB format, with which the layer is cleared before rendering.
-     */
-    internal var backgroundColor: Int
-
     /**
      * Underlying platform component.
      */
     val component: Any?
 
-    /**
-     * A list of rectangles to cut out from the rendered content; No content will be drawn inside them.
-     */
-    internal val cutoutRectangles: List<ClipRectangle>
-
     /**
      * Current view used for rendering.
      */

skiko/src/commonMain/kotlin/org/jetbrains/skiko/context/ContextHandler.kt

@@ -42,54 +42,8 @@ internal abstract class ContextHandler(
         initCanvas()
         canvas?.runRestoringState {
             clear(Color.TRANSPARENT)
-
-            val scale = layer.contentScale
-            for (clip in layer.cutoutRectangles) {
-                cutoutFromClip(clip, scale)
-            }
-
-            val layerBg = layer.backgroundColor
-            clear(
-                if (layer.transparency && isTransparentBackgroundSupported()) {
-                    layerBg
-                } else {
-                    layerBg or 0xFF000000.toInt()
-                }
-            )
-
             drawContent()
         }
         flush()
     }
-
-    protected open fun isTransparentBackgroundSupported(): Boolean {
-        if (hostOs == OS.MacOS) {
-            // macOS transparency is always supported
-            return true
-        }
-
-        // for non-macOS in fullscreen transparency is not supported
-        return !layer.fullscreen
-    }
-}
-
-@Suppress("NOTHING_TO_INLINE")
-internal inline fun Canvas.cutoutFromClip(rectangle: ClipRectangle, scale: Float) {
-    clipRect(
-        left = rectangle.x * scale,
-        top = rectangle.y * scale,
-        right = (rectangle.x + rectangle.width) * scale,
-        bottom = (rectangle.y + rectangle.height) * scale,
-        mode = ClipMode.DIFFERENCE,
-        antiAlias = true
-    )
-}
-
-private inline fun Canvas.runRestoringState(block: Canvas.() -> Unit) {
-    val restoreCount = save()
-    try {
-        block()
-    } finally {
-        restoreToCount(restoreCount)
-    }
 }
\ No newline at end of file

skiko/src/commonMain/kotlin/org/jetbrains/skiko/redrawer/Redrawer.kt

 package org.jetbrains.skiko.redrawer
 
+import org.jetbrains.skiko.OS
+import org.jetbrains.skiko.SkiaLayer
+import org.jetbrains.skiko.hostOs
 import kotlin.time.TimeSource
 
 private val initialTime = TimeSource.Monotonic.markNow()
@@ -12,4 +15,15 @@ internal interface Redrawer {
     fun update(nanoTime: Long = initialTime.elapsedNow().inWholeNanoseconds)
     fun setVisible(isVisible: Boolean) = Unit
     val renderInfo: String
+    fun isTransparentBackgroundSupported(): Boolean
+}
+
+internal fun defaultIsTransparentBackgroundSupported(layer: SkiaLayer): Boolean {
+    if (hostOs == OS.MacOS) {
+        // macOS transparency is always supported
+        return true
+    }
+
+    // for non-macOS in fullscreen transparency is not supported
+    return !layer.fullscreen
 }
\ No newline at end of file

skiko/src/linuxMain/kotlin/org/jetbrains/skiko/SkiaLayer.linux.kt

@@ -12,16 +12,8 @@ actual open class SkiaLayer  {
     actual var fullscreen: Boolean
         get() = TODO("Not yet implemented")
         set(value) {}
-    actual var transparency: Boolean
-        get() = TODO("Not yet implemented")
-        set(value) {}
-    internal actual var backgroundColor: Int
-        get() = TODO("Not yet implemented")
-        set(value) {}
     actual val component: Any?
         get() = TODO("Not yet implemented")
-    internal actual val cutoutRectangles: List<ClipRectangle>
-        get() = emptyList()
     actual fun needRender(throttledToVsync: Boolean) {
         TODO("unimplemented")
     }

skiko/src/macosMain/kotlin/org/jetbrains/skiko/SkiaLayer.macos.kt

@@ -49,24 +49,6 @@ actual open class SkiaLayer {
             if (value) throw IllegalArgumentException("fullscreen unsupported")
         }
 
-    /**
-     * Transparency is not supported on macOS native.
-     */
-    actual var transparency: Boolean
-        get() = false
-        set(value) {
-            if (value) throw IllegalArgumentException("transparency unsupported")
-        }
-
-    /**
-     * The background color of the layer.
-     */
-    internal actual var backgroundColor: Int = Color.WHITE
-        set(value) {
-            field = value
-            needRender()
-        }
-
     /**
      * Underlying [NSView]
      */
@@ -76,9 +58,6 @@ actual open class SkiaLayer {
     actual val component: Any?
         get() = this.nsView
 
-    internal actual val cutoutRectangles: List<ClipRectangle>
-        get() = emptyList()
-
     /**
      * Implements rendering logic and events processing.
      */
@@ -172,7 +151,9 @@ actual open class SkiaLayer {
         val pictureWidth = (width * contentScale).coerceAtLeast(0.0)
         val pictureHeight = (height * contentScale).coerceAtLeast(0.0)
 
-        val canvas = pictureRecorder.beginRecording(0f, 0f, pictureWidth.toFloat(), pictureHeight.toFloat())
+        val canvas = pictureRecorder.beginRecording(0f, 0f, pictureWidth.toFloat(), pictureHeight.toFloat()).apply {
+            clear(Color.WHITE)
+        }
         renderDelegate?.onRender(canvas, pictureWidth.toInt(), pictureHeight.toInt(), nanoTime)
 
         val picture = pictureRecorder.finishRecordingAsPicture()

skiko/src/macosMain/kotlin/org/jetbrains/skiko/redrawer/MetalRedrawer.macos.kt

@@ -191,6 +191,8 @@ internal class MacOsMetalRedrawer(
             }
         }
     }
+
+    override fun isTransparentBackgroundSupported() = defaultIsTransparentBackgroundSupported(skiaLayer)
 }
 
 internal class MetalLayer : CAMetalLayer {

skiko/src/macosMain/kotlin/org/jetbrains/skiko/redrawer/OpenGLRedrawer.macos.kt

@@ -78,6 +78,8 @@ internal class MacOsOpenGLRedrawer(
         glLayer.setNeedsDisplay()
         skiaLayer.nsView.setNeedsDisplay(true)
     }
+
+    override fun isTransparentBackgroundSupported() = defaultIsTransparentBackgroundSupported(skiaLayer)
 }
 
 internal class MacosGLLayer : CAOpenGLLayer {

skiko/src/uikitMain/kotlin/org/jetbrains/skiko/SkiaLayer.uikit.kt

@@ -20,19 +20,6 @@ actual open class SkiaLayer {
         get() = true
         set(_) { throw UnsupportedOperationException() }
 
-    actual var transparency: Boolean
-        get() = false
-        set(_) { throw UnsupportedOperationException() }
-
-    /**
-     * The background color of the layer, as transparency is not supported.
-     */
-    internal actual var backgroundColor: Int = Color.WHITE
-        set(value) {
-            field = value
-            needRender()
-        }
-
     actual fun needRender(throttledToVsync: Boolean) {
         needRedrawCallback.invoke()
     }
@@ -46,9 +33,6 @@ actual open class SkiaLayer {
     actual val component: Any?
         get() = this.view
 
-    internal actual val cutoutRectangles: List<ClipRectangle>
-        get() = emptyList()
-
     val width: Float
        get() = view!!.frame.useContents {
            return@useContents size.width.toFloat()
@@ -80,7 +64,9 @@ actual open class SkiaLayer {
     }
 
     internal fun draw(surface: Surface) {
-        renderDelegate?.onRender(surface.canvas, surface.width, surface.height, currentNanoTime())
+        val canvas = surface.canvas
+        canvas.clear(Color.WHITE)
+        renderDelegate?.onRender(canvas, surface.width, surface.height, currentNanoTime())
     }
 
     actual val pixelGeometry: PixelGeometry

skiko/src/webMain/kotlin/org/jetbrains/skiko/SkiaLayer.js.kt

@@ -37,24 +37,6 @@ actual open class SkiaLayer {
             if (value) throw Exception("Fullscreen is not supported!")
         }
 
-    /**
-     * Transparency is not supported
-     */
-    actual var transparency: Boolean
-        get() = false
-        set(value) {
-            if (value) throw Exception("Transparency is not supported!")
-        }
-
-    /**
-     * The background color of the layer, as transparency is not supported.
-     */
-    internal actual var backgroundColor: Int = Color.WHITE
-        set(value) {
-            field = value
-            needRender()
-        }
-
     /**
      * Schedules a drawFrame to the appropriate moment.
      */
@@ -88,9 +70,6 @@ actual open class SkiaLayer {
     actual val component: Any?
         get() = this.htmlCanvas
 
-    internal actual val cutoutRectangles: List<ClipRectangle>
-        get() = emptyList()
-
     private var htmlCanvas: HTMLCanvasElement? = null
 
     /**
@@ -110,6 +89,7 @@ actual open class SkiaLayer {
     }
 
     internal actual fun draw(canvas: Canvas) {
+        canvas.clear(Color.WHITE)
         renderDelegate?.onRender(canvas, state!!.width, state!!.height, currentNanoTime())
     }