Don't persist cutout clip in ContextHandler (#1177)

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

@@ -1375,14 +1375,13 @@ class SkiaLayerTest {
             }
 
             swingComponent.bounds = Rectangle(0, 200, 300, 100)
-            layer.clipComponents.add(
-                ClipRectangle(
-                    x = swingComponent.x.toFloat(),
-                    y = swingComponent.y.toFloat(),
-                    width = swingComponent.width.toFloat(),
-                    height = swingComponent.height.toFloat()
-                )
+            val clipRect = ClipRectangle(
+                x = swingComponent.x.toFloat(),
+                y = swingComponent.y.toFloat(),
+                width = swingComponent.width.toFloat(),
+                height = swingComponent.height.toFloat()
             )
+            layer.clipComponents.add(clipRect)
 
             layeredPane.add(layer, BorderLayout.CENTER)
             layeredPane.add(swingComponent, BorderLayout.CENTER, 0)
@@ -1396,6 +1395,7 @@ class SkiaLayerTest {
             window.isUndecorated = true
             window.isVisible = true
 
+            delay(100)
             withContext(Dispatchers.Default) {
                 Robot().waitForIdle()
             }
@@ -1404,7 +1404,21 @@ class SkiaLayerTest {
             // - Red, from the layer content
             // - Yellow, from the layer background
             // - Green, from the Swing component
-            screenshots.assert(window.bounds, "frame")
+            screenshots.assert(window.bounds, "frame_1")
+
+            // Remove the swingComponent and its clip
+            layeredPane.remove(swingComponent)
+            layer.clipComponents.remove(clipRect)
+
+            delay(100)
+            withContext(Dispatchers.Default) {
+                Robot().waitForIdle()
+            }
+
+            // Expect to see two layers:
+            // - Red, from the layer content
+            // - Yellow, from the layer background (twice as tall as the Red)
+            screenshots.assert(window.bounds, "frame_2")
         } finally {
             window.close()
         }

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

@@ -40,7 +40,7 @@ internal abstract class ContextHandler(
             throw RenderException("Cannot init graphic context")
         }
         initCanvas()
-        canvas?.apply {
+        canvas?.runRestoringState {
             clear(Color.TRANSPARENT)
 
             val scale = layer.contentScale
@@ -83,4 +83,13 @@ internal inline fun Canvas.cutoutFromClip(rectangle: ClipRectangle, scale: Float
         mode = ClipMode.DIFFERENCE,
         antiAlias = true
     )
+}
+
+private inline fun Canvas.runRestoringState(block: Canvas.() -> Unit) {
+    val restoreCount = save()
+    try {
+        block()
+    } finally {
+        restoreToCount(restoreCount)
+    }
 }
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