Add keyboard preview on ThemeScreen (#1422)

Signed-off-by: Aleksandras Kostarevas <[email protected]>

Author: barmiro

java/src/org/futo/inputmethod/latin/uix/settings/pages/ThemeScreen.kt

@@ -1,30 +1,111 @@
 package org.futo.inputmethod.latin.uix.settings.pages
 
+import android.app.Activity
+import android.os.Build
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.padding
+import androidx.compose.material3.FabPosition
+import androidx.compose.material3.Scaffold
+import androidx.compose.material3.SmallFloatingActionButton
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.DisposableEffect
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.platform.LocalContext
+import androidx.compose.ui.platform.LocalTextInputService
 import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.text.input.ImeOptions
+import androidx.compose.ui.text.input.PlatformImeOptions
+import androidx.compose.ui.text.input.TextFieldValue
+import androidx.compose.ui.text.input.TextInputSession
 import androidx.compose.ui.tooling.preview.Preview
+import androidx.core.view.ViewCompat
+import androidx.core.view.WindowInsetsCompat
 import androidx.navigation.NavHostController
 import androidx.navigation.compose.rememberNavController
 import org.futo.inputmethod.latin.uix.THEME_KEY
 import org.futo.inputmethod.latin.uix.settings.ScreenTitle
 import org.futo.inputmethod.latin.uix.settings.useDataStore
 import org.futo.inputmethod.latin.uix.theme.selector.ThemePicker
 import org.futo.inputmethod.latin.R
+import org.futo.inputmethod.latin.uix.settings.RotatingChevronIcon
 
 @Preview
 @Composable
 fun ThemeScreen(navController: NavHostController = rememberNavController()) {
     val (theme, setTheme) = useDataStore(THEME_KEY.key, THEME_KEY.default)
 
     val context = LocalContext.current
-    Column(modifier = Modifier.fillMaxSize()) {
-        ScreenTitle(stringResource(R.string.theme_settings_title), showBack = true, navController)
-        ThemePicker {
-            setTheme(it.key)
+    val enableKeyboardPreview = Build.VERSION.SDK_INT >= Build.VERSION_CODES.R
+    var showKeyboard by remember { mutableStateOf(false) }
+
+    if (enableKeyboardPreview) {
+        val textInputService = LocalTextInputService.current
+        val rootView = (context as? Activity)?.window?.decorView?.rootView
+        val session = remember { mutableStateOf<TextInputSession?>(null) }
+
+        DisposableEffect(showKeyboard, theme) {
+            val service = textInputService ?: return@DisposableEffect onDispose { }
+
+            if (showKeyboard) {
+                session.value = service.startInput(
+                    TextFieldValue(""),
+                    imeOptions = ImeOptions.Default.copy(
+                        platformImeOptions = PlatformImeOptions(
+                            privateImeOptions = "org.futo.inputmethod.latin.NoSuggestions=1"
+                        )
+                    ),
+                    onEditCommand = { },
+                    onImeActionPerformed = { }
+                )
+            }
+
+            onDispose {
+                service.stopInput(session.value ?: return@onDispose)
+            }
+        }
+
+        // Detect manual keyboard dismissal (e.g., back button press)
+        rootView?.let { view ->
+            DisposableEffect(view) {
+                ViewCompat.setOnApplyWindowInsetsListener(view) { _, insets ->
+                    val isKeyboardVisible = insets.isVisible(WindowInsetsCompat.Type.ime())
+                    if (!isKeyboardVisible && showKeyboard) {
+                        showKeyboard = false
+                    }
+                    insets
+                }
+
+                onDispose {
+                    ViewCompat.setOnApplyWindowInsetsListener(view, null)
+                }
+            }
+        }
+    }
+
+    Scaffold(
+        floatingActionButton = {
+            if (enableKeyboardPreview) {
+                SmallFloatingActionButton(
+                    onClick = {
+                        showKeyboard = !showKeyboard
+                    }
+                ) {
+                    RotatingChevronIcon(!showKeyboard)
+                }
+            }
+        },
+        floatingActionButtonPosition = FabPosition.Start
+    ) { innerPadding ->
+        Column(modifier = Modifier.fillMaxSize().padding(innerPadding)) {
+            ScreenTitle(stringResource(R.string.theme_settings_title), showBack = true, navController)
+            ThemePicker {
+                setTheme(it.key)
+            }
         }
     }
 }