Add dedicated feature flags class for desktop

compose/ui/ui/src/desktopMain/kotlin/androidx/compose/ui/ComposeFeatureFlags.kt

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package androidx.compose.ui
+
+import androidx.compose.ui.window.Dialog
+import androidx.compose.ui.window.Popup
+
+/**
+ * The helper singleton object that provides the access to feature flags that
+ * configure Compose behaviour.
+ */
+internal object ComposeFeatureFlags {
+    /**
+     * Indicates whether the Compose should use Swing graphics for rendering.
+     * This prevents transitional rendering issues when panels are being shown, hidden, or resized.
+     * It also enables proper layering when combining Swing components and compose panels.
+     *
+     * Please note that it requires additional copy from offscreen texture to Swing graphics,
+     * so it has some performance penalty.
+     */
+    val useSwingGraphics: Boolean
+        get() = System.getProperty("compose.swing.render.on.graphics").toBoolean()
+
+    /**
+     * Indicates whether interop blending is enabled.
+     * It allows drawing compose elements above interop and apply clip/shape modifiers to it.
+     *
+     * Note that it currently works only with Metal, DirectX and offscreen rendering.
+     */
+    val useInteropBlending: Boolean
+        get() = System.getProperty("compose.interop.blending").toBoolean()
+}

compose/ui/ui/src/desktopMain/kotlin/androidx/compose/ui/awt/ComposePanel.desktop.kt

@@ -17,6 +17,7 @@ package androidx.compose.ui.awt
 
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.CompositionLocalProvider
+import androidx.compose.ui.ComposeFeatureFlags
 import androidx.compose.ui.ExperimentalComposeUiApi
 import androidx.compose.ui.focus.FocusDirection
 import androidx.compose.ui.window.WindowExceptionHandler
@@ -200,13 +201,9 @@ class ComposePanel @ExperimentalComposeUiApi constructor(
     private val componentLayer: Int
         get() = if (interopBlending) 0 else 20
 
-    private val renderOnGraphics: Boolean
-        get() = System.getProperty("compose.swing.render.on.graphics").toBoolean()
-    private val _interopBlending: Boolean
-        get() = System.getProperty("compose.interop.blending").toBoolean()
     private val interopBlending: Boolean
-        get() = _interopBlending &&
-            (renderOnGraphics || requireNotNull(bridge).interopBlendingSupported)
+        get() = ComposeFeatureFlags.useInteropBlending &&
+            (ComposeFeatureFlags.useSwingGraphics || requireNotNull(bridge).interopBlendingSupported)
 
     override fun addNotify() {
         super.addNotify()
@@ -223,7 +220,7 @@ class ComposePanel @ExperimentalComposeUiApi constructor(
     }
 
     private fun createComposeBridge(): ComposeBridge {
-        val bridge: ComposeBridge = if (renderOnGraphics) {
+        val bridge: ComposeBridge = if (ComposeFeatureFlags.useSwingGraphics) {
             SwingComposeBridge(skiaLayerAnalytics, layoutDirectionFor(this))
         } else {
             WindowComposeBridge(skiaLayerAnalytics, layoutDirectionFor(this))

compose/ui/ui/src/desktopMain/kotlin/androidx/compose/ui/awt/ComposeWindowDelegate.desktop.kt

@@ -19,6 +19,7 @@ package androidx.compose.ui.awt
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.CompositionLocalContext
 import androidx.compose.runtime.CompositionLocalProvider
+import androidx.compose.ui.ComposeFeatureFlags
 import androidx.compose.ui.ExperimentalComposeUiApi
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.input.key.KeyEvent
@@ -93,10 +94,8 @@ internal class ComposeWindowDelegate(
     val renderApi: GraphicsApi
         get() = bridge.renderApi
 
-    private val _interopBlending: Boolean
-        get() = System.getProperty("compose.interop.blending").toBoolean()
     private val interopBlending: Boolean
-        get() = _interopBlending && bridge.interopBlendingSupported
+        get() = ComposeFeatureFlags.useInteropBlending && bridge.interopBlendingSupported
 
     var isWindowTransparent: Boolean = false
         set(value) {