Feat/system palette

android/app/src/main/kotlin/dev/so1ve/bitree/BuildingColors.kt

@@ -2,19 +2,64 @@ package dev.so1ve.bitree
 
 import android.content.Context
 import android.content.res.Configuration
+import android.util.Log
 import org.json.JSONArray
 import org.json.JSONObject
 
 internal object BuildingColors {
     private data class Palette(val light: IntArray, val dark: IntArray)
-    private data class Rule(val name: String, val pattern: Regex, val palette: Palette)
+    private data class Rule(
+        val name: String,
+        val area: String?,
+        val pattern: Regex,
+        val palette: Palette,
+    )
     private data class Match(val start: Int, val end: Int, val rule: Rule)
     private data class Table(val neutral: Palette, val rules: List<Rule>)
 
     private var table: Table? = null
+    private val customColors = mutableMapOf<Boolean, Map<String, IntArray>>()
+    private const val PREFERENCES = "widget_appearance"
+    private fun colorsKey(dark: Boolean) = if (dark) "darkCourseColors" else "lightCourseColors"
     private val otherCampuses = Regex("中关村|西山|珠海|雄安|怀来")
     private val spacing = Regex("[\\s\\u00A0\\u3000·._\\-—–（）()\\[\\]【】]")
 
+    fun savePalette(context: Context, dark: Boolean, colors: Map<String, List<Number>>) {
+        context.getSharedPreferences(PREFERENCES, Context.MODE_PRIVATE).edit()
+            .putString(colorsKey(dark), JSONObject(colors).toString()).apply()
+        customColors[dark] = colors.mapValues { (_, values) ->
+            values.map { it.toInt() }.toIntArray()
+        }
+    }
+
+    private fun readPalette(context: Context, dark: Boolean): Map<String, IntArray> {
+        return customColors[dark] ?: run {
+            try {
+                val saved = context.getSharedPreferences(PREFERENCES, Context.MODE_PRIVATE)
+                    .getString(colorsKey(dark), "{}") ?: "{}"
+                val json = JSONObject(saved)
+                json.keys().asSequence().associateWith { area ->
+                    val values = json.getJSONArray(area)
+                    require(values.length() == 2)
+                    IntArray(2) { values.getLong(it).toInt() }
+                }
+            } catch (error: Exception) {
+                Log.w("BITree", "无法读取桌面组件的课程配色", error)
+                emptyMap()
+            }.also { customColors[dark] = it }
+        }
+    }
+
+    fun widgetBackground(context: Context): Int {
+        val fallback = context.getColor(R.color.widget_surface)
+        if (!isDark(context)) return fallback
+        return readPalette(context, true)["surface"]?.firstOrNull() ?: fallback
+    }
+
+    private fun isDark(context: Context): Boolean =
+        context.resources.configuration.uiMode and
+            Configuration.UI_MODE_NIGHT_MASK == Configuration.UI_MODE_NIGHT_YES
+
     fun forCourse(context: Context, room: String, campus: String): IntArray {
         val data = table ?: read(context).also { table = it }
         val normalized = room.map { char ->
@@ -33,10 +78,12 @@ internal object BuildingColors {
                     other.end - other.start > match.end - match.start
             }
         }.map { it.rule }.distinctBy { it.name }
-        val palette = buildings.singleOrNull()?.palette ?: data.neutral
-        val dark = context.resources.configuration.uiMode and
-            Configuration.UI_MODE_NIGHT_MASK == Configuration.UI_MODE_NIGHT_YES
-        return if (dark) palette.dark else palette.light
+        val building = buildings.singleOrNull()
+        val palette = building?.palette ?: data.neutral
+        WidgetColors.course(context, building?.area)?.let { return it }
+        val dark = isDark(context)
+        return readPalette(context, dark)[building?.area ?: "neutral"]
+            ?: if (dark) palette.dark else palette.light
     }
 
     private fun read(context: Context): Table {
@@ -52,7 +99,12 @@ internal object BuildingColors {
             palette(json.getJSONObject("neutral")),
             (0 until rows.length()).map { index ->
                 val row = rows.getJSONObject(index)
-                Rule(row.getString("name"), Regex(row.getString("pattern")), palette(row))
+                Rule(
+                    row.getString("name"),
+                    row.optString("area").takeIf { it.isNotEmpty() },
+                    Regex(row.getString("pattern")),
+                    palette(row),
+                )
             },
         )
     }

android/app/src/main/kotlin/dev/so1ve/bitree/MainActivity.kt

@@ -1,20 +1,61 @@
 package dev.so1ve.bitree
 
+import android.content.res.Configuration
 import io.flutter.embedding.android.FlutterActivity
 import io.flutter.embedding.engine.FlutterEngine
 import io.flutter.plugin.common.MethodChannel
 
 class MainActivity : FlutterActivity() {
+    private var themeChannel: MethodChannel? = null
+
+    override fun onResume() {
+        super.onResume()
+        // Wallpaper colours may have changed while the app was in the background.
+        themeChannel?.invokeMethod("changed", null)
+    }
+
+    override fun onConfigurationChanged(newConfig: Configuration) {
+        super.onConfigurationChanged(newConfig)
+        TimetableWidget.updateAll(this)
+        themeChannel?.invokeMethod("changed", null)
+    }
+
     override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
         super.configureFlutterEngine(flutterEngine)
+        themeChannel = MethodChannel(
+            flutterEngine.dartExecutor.binaryMessenger, "dev.so1ve.bitree/theme",
+        ).also { channel ->
+            channel.setMethodCallHandler { call, result ->
+                if (call.method == "getSystemPalette") {
+                    result.success(SystemPalette.read(this))
+                } else {
+                    result.notImplemented()
+                }
+            }
+        }
         MethodChannel(flutterEngine.dartExecutor.binaryMessenger, "dev.so1ve.bitree/widget")
             .setMethodCallHandler { call, result ->
                 if (call.method == "update") {
+                    call.argument<Map<String, List<Number>>>("lightCourseColors")?.let {
+                        BuildingColors.savePalette(this, false, it)
+                    }
+                    call.argument<Map<String, List<Number>>>("darkCourseColors")?.let {
+                        BuildingColors.savePalette(this, true, it)
+                    }
+                    call.argument<Boolean>("useSystemPalette")?.let {
+                        WidgetColors.saveUseSystemPalette(this, it)
+                    }
                     TimetableWidget.updateAll(this)
                     result.success(null)
                 } else {
                     result.notImplemented()
                 }
             }
     }
+
+    override fun cleanUpFlutterEngine(flutterEngine: FlutterEngine) {
+        themeChannel?.setMethodCallHandler(null)
+        themeChannel = null
+        super.cleanUpFlutterEngine(flutterEngine)
+    }
 }

android/app/src/main/kotlin/dev/so1ve/bitree/SystemPalette.kt

@@ -0,0 +1,49 @@
+package dev.so1ve.bitree
+
+import android.content.Context
+import android.os.Build
+
+/** Export Android 12+ tonal resources; older devices retain the app palette. */
+internal object SystemPalette {
+    fun read(context: Context): Map<String, List<Int>>? {
+        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.S) return null
+        val families = mapOf(
+            "accent1" to intArrayOf(
+                android.R.color.system_accent1_0, android.R.color.system_accent1_10, android.R.color.system_accent1_50,
+                android.R.color.system_accent1_100, android.R.color.system_accent1_200, android.R.color.system_accent1_300,
+                android.R.color.system_accent1_400, android.R.color.system_accent1_500, android.R.color.system_accent1_600,
+                android.R.color.system_accent1_700, android.R.color.system_accent1_800, android.R.color.system_accent1_900,
+                android.R.color.system_accent1_1000,
+            ),
+            "accent2" to intArrayOf(
+                android.R.color.system_accent2_0, android.R.color.system_accent2_10, android.R.color.system_accent2_50,
+                android.R.color.system_accent2_100, android.R.color.system_accent2_200, android.R.color.system_accent2_300,
+                android.R.color.system_accent2_400, android.R.color.system_accent2_500, android.R.color.system_accent2_600,
+                android.R.color.system_accent2_700, android.R.color.system_accent2_800, android.R.color.system_accent2_900,
+                android.R.color.system_accent2_1000,
+            ),
+            "accent3" to intArrayOf(
+                android.R.color.system_accent3_0, android.R.color.system_accent3_10, android.R.color.system_accent3_50,
+                android.R.color.system_accent3_100, android.R.color.system_accent3_200, android.R.color.system_accent3_300,
+                android.R.color.system_accent3_400, android.R.color.system_accent3_500, android.R.color.system_accent3_600,
+                android.R.color.system_accent3_700, android.R.color.system_accent3_800, android.R.color.system_accent3_900,
+                android.R.color.system_accent3_1000,
+            ),
+            "neutral1" to intArrayOf(
+                android.R.color.system_neutral1_0, android.R.color.system_neutral1_10, android.R.color.system_neutral1_50,
+                android.R.color.system_neutral1_100, android.R.color.system_neutral1_200, android.R.color.system_neutral1_300,
+                android.R.color.system_neutral1_400, android.R.color.system_neutral1_500, android.R.color.system_neutral1_600,
+                android.R.color.system_neutral1_700, android.R.color.system_neutral1_800, android.R.color.system_neutral1_900,
+                android.R.color.system_neutral1_1000,
+            ),
+            "neutral2" to intArrayOf(
+                android.R.color.system_neutral2_0, android.R.color.system_neutral2_10, android.R.color.system_neutral2_50,
+                android.R.color.system_neutral2_100, android.R.color.system_neutral2_200, android.R.color.system_neutral2_300,
+                android.R.color.system_neutral2_400, android.R.color.system_neutral2_500, android.R.color.system_neutral2_600,
+                android.R.color.system_neutral2_700, android.R.color.system_neutral2_800, android.R.color.system_neutral2_900,
+                android.R.color.system_neutral2_1000,
+            ),
+        )
+        return families.mapValues { (_, colors) -> colors.map { context.getColor(it) } }
+    }
+}

android/app/src/main/kotlin/dev/so1ve/bitree/TimetableWidget.kt

@@ -75,6 +75,12 @@ open class TimetableWidget : AppWidgetProvider() {
             )
             widgets.forEach { (id, columns) ->
                 val views = RemoteViews(context.packageName, R.layout.timetable_widget)
+                views.setInt(
+                    R.id.widget_content, "setBackgroundColor", WidgetColors.background(context),
+                )
+                views.setTextColor(R.id.widget_date, WidgetColors.text(context))
+                views.setTextColor(R.id.widget_empty, WidgetColors.muted(context))
+                views.setTextColor(R.id.widget_message, WidgetColors.accent(context))
                 views.setTextViewText(R.id.widget_date, content.heading)
                 views.setTextViewText(R.id.widget_empty, content.emptyMessage)
                 views.setEmptyView(R.id.widget_courses, R.id.widget_empty)

android/app/src/main/kotlin/dev/so1ve/bitree/WidgetColors.kt

@@ -0,0 +1,91 @@
+package dev.so1ve.bitree
+
+import android.content.Context
+import android.content.res.Configuration
+import android.os.Build
+
+/** Widget surfaces follow Android; courses opt into the system palette separately. */
+internal object WidgetColors {
+    private const val PREFERENCES = "widget_appearance"
+    private const val USE_SYSTEM_PALETTE = "useSystemPalette"
+
+    fun saveUseSystemPalette(context: Context, enabled: Boolean) {
+        context.getSharedPreferences(PREFERENCES, Context.MODE_PRIVATE).edit()
+            .putBoolean(USE_SYSTEM_PALETTE, enabled).apply()
+    }
+
+    fun background(context: Context): Int =
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) {
+            context.getColor(R.color.widget_system_surface)
+        } else {
+            BuildingColors.widgetBackground(context)
+        }
+
+    fun text(context: Context): Int = context.getColor(
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) R.color.widget_system_text
+        else R.color.widget_text,
+    )
+
+    fun muted(context: Context): Int = context.getColor(
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) R.color.widget_system_muted
+        else R.color.widget_muted,
+    )
+
+    fun accent(context: Context): Int = context.getColor(
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) R.color.widget_system_accent
+        else R.color.widget_accent,
+    )
+
+    /** Preserve campus grouping with three system accent families and tonal variations. */
+    fun course(context: Context, area: String?): IntArray? {
+        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.S) return null
+        if (!context.getSharedPreferences(PREFERENCES, Context.MODE_PRIVATE)
+                .getBoolean(USE_SYSTEM_PALETTE, false)) return null
+        val dark = context.resources.configuration.uiMode and
+            Configuration.UI_MODE_NIGHT_MASK == Configuration.UI_MODE_NIGHT_YES
+        val colors = if (dark) {
+            when (area) {
+                "northTeaching" -> intArrayOf(
+                    android.R.color.system_accent1_700, android.R.color.system_accent1_100,
+                )
+                "wencui" -> intArrayOf(
+                    android.R.color.system_accent2_700, android.R.color.system_accent2_100,
+                )
+                "southScience" -> intArrayOf(
+                    android.R.color.system_accent3_700, android.R.color.system_accent3_100,
+                )
+                "eastFacilities" -> intArrayOf(
+                    android.R.color.system_accent1_800, android.R.color.system_accent1_100,
+                )
+                "southEngineering" -> intArrayOf(
+                    android.R.color.system_accent3_800, android.R.color.system_accent3_100,
+                )
+                else -> intArrayOf(
+                    android.R.color.system_neutral2_700, android.R.color.system_neutral2_100,
+                )
+            }
+        } else {
+            when (area) {
+                "northTeaching" -> intArrayOf(
+                    android.R.color.system_accent1_100, android.R.color.system_accent1_900,
+                )
+                "wencui" -> intArrayOf(
+                    android.R.color.system_accent2_100, android.R.color.system_accent2_900,
+                )
+                "southScience" -> intArrayOf(
+                    android.R.color.system_accent3_100, android.R.color.system_accent3_900,
+                )
+                "eastFacilities" -> intArrayOf(
+                    android.R.color.system_accent1_50, android.R.color.system_accent1_900,
+                )
+                "southEngineering" -> intArrayOf(
+                    android.R.color.system_accent3_50, android.R.color.system_accent3_900,
+                )
+                else -> intArrayOf(
+                    android.R.color.system_neutral2_100, android.R.color.system_neutral2_900,
+                )
+            }
+        }
+        return colors.map { context.getColor(it) }.toIntArray()
+    }
+}

android/app/src/main/res/layout/timetable_widget.xml

@@ -1,41 +1,46 @@
 <?xml version="1.0" encoding="utf-8"?>
-<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:id="@+id/widget_root"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
-    android:orientation="vertical"
-    android:paddingStart="@dimen/widget_padding"
-    android:paddingEnd="@dimen/widget_padding"
-    android:paddingTop="8dp"
-    android:paddingBottom="8dp"
     android:background="@drawable/widget_background"
     android:clipToOutline="true">
-    <include layout="@layout/widget_header" />
-    <FrameLayout
+    <LinearLayout
+        android:id="@+id/widget_content"
         android:layout_width="match_parent"
-        android:layout_height="0dp"
-        android:layout_weight="1"
-        android:layout_marginTop="6dp">
-        <ListView
-            android:id="@+id/widget_courses"
+        android:layout_height="match_parent"
+        android:orientation="vertical"
+        android:paddingStart="@dimen/widget_padding"
+        android:paddingEnd="@dimen/widget_padding"
+        android:paddingTop="8dp"
+        android:paddingBottom="8dp">
+        <include layout="@layout/widget_header" />
+        <FrameLayout
             android:layout_width="match_parent"
-            android:layout_height="wrap_content"
-            android:divider="@null"
-            android:dividerHeight="0dp"
-            android:scrollbars="vertical"
-            android:scrollbarStyle="insideOverlay"
-            android:scrollbarSize="2dp"
-            android:clipToPadding="false"
-            android:requiresFadingEdge="vertical"
-            android:fadingEdgeLength="12dp"
-            android:cacheColorHint="@color/widget_surface" />
-        <TextView
-            android:id="@+id/widget_empty"
-            android:layout_width="match_parent"
-            android:layout_height="match_parent"
-            android:gravity="center"
-            android:text="@string/widget_today_empty"
-            android:textColor="@color/widget_muted"
-            android:textSize="13sp" />
-    </FrameLayout>
-</LinearLayout>
+            android:layout_height="0dp"
+            android:layout_weight="1"
+            android:layout_marginTop="6dp">
+            <ListView
+                android:id="@+id/widget_courses"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:divider="@null"
+                android:dividerHeight="0dp"
+                android:scrollbars="vertical"
+                android:scrollbarStyle="insideOverlay"
+                android:scrollbarSize="2dp"
+                android:clipToPadding="false"
+                android:requiresFadingEdge="vertical"
+                android:fadingEdgeLength="12dp"
+                android:cacheColorHint="@android:color/transparent" />
+            <TextView
+                android:id="@+id/widget_empty"
+                android:layout_width="match_parent"
+                android:layout_height="match_parent"
+                android:gravity="center"
+                android:text="@string/widget_today_empty"
+                android:textColor="@color/widget_muted"
+                android:textSize="13sp" />
+        </FrameLayout>
+    </LinearLayout>
+</FrameLayout>