From 0b1d89f06dfdf6e99335c3aff904cc5fb381fddb Mon Sep 17 00:00:00 2001
From: xfy <i@rua.plus>
Date: Tue, 19 May 2026 17:34:43 +0800
Subject: [PATCH] =?UTF-8?q?feat:=20=E6=96=B0=E5=A2=9E=20BackHandler=20expe?=
 =?UTF-8?q?ct/actual=20=E6=8B=A6=E6=88=AA=E7=B3=BB=E7=BB=9F=E8=BF=94?=
 =?UTF-8?q?=E5=9B=9E=E6=89=8B=E5=8A=BF?=
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Android 通过 androidx.activity.compose.BackHandler 接管返回键，
在关于页与许可页返回上一级；iOS 无系统返回键，actual 为空实现。

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
---
 .../plus/rua/project/Platform.android.kt      |  8 +++++++-
 .../commonMain/kotlin/plus/rua/project/App.kt | 20 ++++++++++++-------
 .../kotlin/plus/rua/project/Platform.kt       | 13 +++++++++++-
 .../kotlin/plus/rua/project/Platform.ios.kt   |  8 +++++++-
 4 files changed, 39 insertions(+), 10 deletions(-)

diff --git a/shared/src/androidMain/kotlin/plus/rua/project/Platform.android.kt b/shared/src/androidMain/kotlin/plus/rua/project/Platform.android.kt
index e0ddf8b..39289ab 100644
--- a/shared/src/androidMain/kotlin/plus/rua/project/Platform.android.kt
+++ b/shared/src/androidMain/kotlin/plus/rua/project/Platform.android.kt
@@ -1,6 +1,7 @@
 package plus.rua.project
 
 import android.os.Build
+import androidx.compose.runtime.Composable
 
 class AndroidPlatform : Platform {
     override val name: String = "Android ${Build.VERSION.SDK_INT}"
@@ -10,4 +11,9 @@ actual fun getPlatform(): Platform = AndroidPlatform()
 
 actual fun getGifUri(gifFile: String): String = "file:///android_asset/gifs/$gifFile"
 
-actual fun getAppIconUri(): String = "file:///android_asset/app_icon.png"
\ No newline at end of file
+actual fun getAppIconUri(): String = "file:///android_asset/app_icon.png"
+
+@Composable
+actual fun BackHandler(enabled: Boolean, onBack: () -> Unit) {
+    androidx.activity.compose.BackHandler(enabled = enabled, onBack = onBack)
+}
\ No newline at end of file
diff --git a/shared/src/commonMain/kotlin/plus/rua/project/App.kt b/shared/src/commonMain/kotlin/plus/rua/project/App.kt
index abc6d21..ed79e01 100644
--- a/shared/src/commonMain/kotlin/plus/rua/project/App.kt
+++ b/shared/src/commonMain/kotlin/plus/rua/project/App.kt
@@ -32,13 +32,19 @@ fun App() {
                 modifier = Modifier,
                 onNavigateToAbout = { currentScreen = Screen.About }
             )
-            Screen.About -> AboutScreen(
-                onBack = { currentScreen = Screen.Main },
-                onNavigateToLicenses = { currentScreen = Screen.Licenses }
-            )
-            Screen.Licenses -> LicensesScreen(
-                onBack = { currentScreen = Screen.About }
-            )
+            Screen.About -> {
+                BackHandler { currentScreen = Screen.Main }
+                AboutScreen(
+                    onBack = { currentScreen = Screen.Main },
+                    onNavigateToLicenses = { currentScreen = Screen.Licenses }
+                )
+            }
+            Screen.Licenses -> {
+                BackHandler { currentScreen = Screen.About }
+                LicensesScreen(
+                    onBack = { currentScreen = Screen.About }
+                )
+            }
         }
     }
 }
diff --git a/shared/src/commonMain/kotlin/plus/rua/project/Platform.kt b/shared/src/commonMain/kotlin/plus/rua/project/Platform.kt
index d76804f..6faab22 100644
--- a/shared/src/commonMain/kotlin/plus/rua/project/Platform.kt
+++ b/shared/src/commonMain/kotlin/plus/rua/project/Platform.kt
@@ -1,5 +1,7 @@
 package plus.rua.project
 
+import androidx.compose.runtime.Composable
+
 interface Platform {
     val name: String
 }
@@ -14,4 +16,13 @@ expect fun getPlatform(): Platform
  */
 expect fun getGifUri(gifFile: String): String
 
-expect fun getAppIconUri(): String
\ No newline at end of file
+expect fun getAppIconUri(): String
+
+/**
+ * 拦截系统返回手势。
+ *
+ * @param enabled 是否启用拦截
+ * @param onBack 返回回调
+ */
+@Composable
+expect fun BackHandler(enabled: Boolean = true, onBack: () -> Unit)
\ No newline at end of file
diff --git a/shared/src/iosMain/kotlin/plus/rua/project/Platform.ios.kt b/shared/src/iosMain/kotlin/plus/rua/project/Platform.ios.kt
index 09db9f7..3c1efc8 100644
--- a/shared/src/iosMain/kotlin/plus/rua/project/Platform.ios.kt
+++ b/shared/src/iosMain/kotlin/plus/rua/project/Platform.ios.kt
@@ -1,5 +1,6 @@
 package plus.rua.project
 
+import androidx.compose.runtime.Composable
 import platform.UIKit.UIDevice
 
 class IOSPlatform : Platform {
@@ -11,4 +12,9 @@ actual fun getPlatform(): Platform = IOSPlatform()
 
 actual fun getGifUri(gifFile: String): String = "compose.resource://files/$gifFile"
 
-actual fun getAppIconUri(): String = "compose.resource://files/app_icon.png"
\ No newline at end of file
+actual fun getAppIconUri(): String = "compose.resource://files/app_icon.png"
+
+@Composable
+actual fun BackHandler(enabled: Boolean, onBack: () -> Unit) {
+    // iOS 没有系统返回键，由导航栏按钮处理
+}
\ No newline at end of file