From 9e7dfc4cfcee8f60e31bc016f21fd09836033625 Mon Sep 17 00:00:00 2001
From: Alexander Maryanovsky <msasha@gmail.com>
Date: Thu, 9 May 2024 18:56:26 +0300
Subject: [PATCH] Fix ComposePanel.requestFocus

---
 .../compose/ui/awt/ComposePanel.desktop.kt    |  5 +-
 .../compose/ui/awt/ComposePanelTest.kt        | 62 ++++++++++++++++++-
 2 files changed, 63 insertions(+), 4 deletions(-)

diff --git a/compose/ui/ui/src/desktopMain/kotlin/androidx/compose/ui/awt/ComposePanel.desktop.kt b/compose/ui/ui/src/desktopMain/kotlin/androidx/compose/ui/awt/ComposePanel.desktop.kt
index 6ea597857be97..d726f2c01eba8 100644
--- a/compose/ui/ui/src/desktopMain/kotlin/androidx/compose/ui/awt/ComposePanel.desktop.kt
+++ b/compose/ui/ui/src/desktopMain/kotlin/androidx/compose/ui/awt/ComposePanel.desktop.kt
@@ -216,11 +216,12 @@ class ComposePanel @ExperimentalComposeUiApi constructor(
                             FocusEvent.Cause.TRAVERSAL_FORWARD -> {
                                 focusManager.moveFocus(FocusDirection.Next)
                             }
-
                             FocusEvent.Cause.TRAVERSAL_BACKWARD -> {
                                 focusManager.moveFocus(FocusDirection.Previous)
                             }
-
+                            FocusEvent.Cause.UNKNOWN, FocusEvent.Cause.ACTIVATION -> {
+                                focusManager.moveFocus(FocusDirection.Enter)
+                            }
                             else -> Unit
                         }
                     }
diff --git a/compose/ui/ui/src/desktopTest/kotlin/androidx/compose/ui/awt/ComposePanelTest.kt b/compose/ui/ui/src/desktopTest/kotlin/androidx/compose/ui/awt/ComposePanelTest.kt
index dad5e503218ea..a9289d0299522 100644
--- a/compose/ui/ui/src/desktopTest/kotlin/androidx/compose/ui/awt/ComposePanelTest.kt
+++ b/compose/ui/ui/src/desktopTest/kotlin/androidx/compose/ui/awt/ComposePanelTest.kt
@@ -15,7 +15,9 @@
  */
 package androidx.compose.ui.awt
 
+import androidx.compose.foundation.focusable
 import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.requiredSize
 import androidx.compose.foundation.layout.size
@@ -29,6 +31,7 @@ import androidx.compose.runtime.remember
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.ExperimentalComposeUiApi
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.focus.onFocusChanged
 import androidx.compose.ui.geometry.Size
 import androidx.compose.ui.input.pointer.PointerEventType
 import androidx.compose.ui.input.pointer.onPointerEvent
@@ -36,7 +39,6 @@ import androidx.compose.ui.layout.layout
 import androidx.compose.ui.layout.onGloballyPositioned
 import androidx.compose.ui.sendMouseEvent
 import androidx.compose.ui.unit.Constraints
-import androidx.compose.ui.unit.IntSize
 import androidx.compose.ui.unit.dp
 import androidx.compose.ui.unit.toSize
 import androidx.compose.ui.util.ThrowUncaughtExceptionRule
@@ -47,6 +49,7 @@ import java.awt.BorderLayout
 import java.awt.Dimension
 import java.awt.GraphicsEnvironment
 import java.awt.event.MouseEvent
+import javax.swing.JButton
 import javax.swing.JFrame
 import javax.swing.JPanel
 import junit.framework.TestCase.assertTrue
@@ -459,4 +462,59 @@ class ComposePanelTest {
             window.dispose()
         }
     }
-}
\ No newline at end of file
+
+    @Test
+    fun `requestFocus assigns focus to first focusable element`() = runApplicationTest {
+        assumeFalse(GraphicsEnvironment.getLocalGraphicsEnvironment().isHeadlessInstance)
+
+        var focusedElement: String? = null
+        val composePanel = ComposePanel()
+        composePanel.setBounds(0, 25, 100, 100)
+        composePanel.setContent {
+            Column {
+                Box(Modifier
+                    .size(10.dp)
+                    .onFocusChanged {
+                        focusedElement = if (it.isFocused) "first" else null
+                    }
+                    .focusable()
+                )
+                Box(Modifier
+                    .size(10.dp)
+                    .onFocusChanged {
+                        focusedElement = if (it.isFocused) "second" else null
+                    }
+                    .focusable()
+                )
+            }
+        }
+
+        val frame = JFrame()
+        try {
+            val button = JButton("Button")
+            frame.size = Dimension(500, 500)
+            frame.contentPane.add(button, BorderLayout.NORTH)
+            frame.contentPane.add(composePanel, BorderLayout.CENTER)
+            frame.isVisible = true
+
+            assertEquals(null, focusedElement)
+
+            // The first requestFocus sends a focusGained(Cause.ACTIVATION) event
+            composePanel.requestFocus()
+            awaitIdle()
+            assertEquals("first", focusedElement)
+
+            // Switch focus back to Swing
+            button.requestFocus()
+            awaitIdle()
+            assertEquals(null, focusedElement)
+
+            // The 2nd requestFocus sends a focusGained(Cause.UNKNOWN) event; we want to test both
+            composePanel.requestFocus()
+            awaitIdle()
+            assertEquals("first", focusedElement)
+        } finally {
+            frame.dispose()
+        }
+    }
+}