feat(splash): add reusable SplashScreen composable

core/src/main/kotlin/plus/rua/project/ui/SplashScreen.kt

@@ -0,0 +1,77 @@
+package plus.rua.project.ui
+
+import androidx.compose.foundation.Image
+import androidx.compose.foundation.background
+import androidx.compose.foundation.isSystemInDarkTheme
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.WindowInsets
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.layout.statusBars
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.painter.Painter
+import androidx.compose.ui.layout.ContentScale
+import androidx.compose.ui.platform.LocalConfiguration
+import androidx.compose.ui.platform.LocalDensity
+import androidx.compose.ui.unit.dp
+
+private const val DarkOverlayAlpha = 0.4f
+private val SplashIconSize = 80.dp
+
+/**
+ * 品牌启动页 UI。
+ *
+ * 背景图铺满全屏，暗色模式下叠加半透明黑色蒙层降低亮度。
+ * app icon 水平居中，其垂直中心位于状态栏下方可用区域高度的约 25% 处。
+ * 图片仅用于装饰，因此 contentDescription 为 null。
+ *
+ * @param backgroundPainter 启动背景图的 Painter
+ * @param iconPainter app icon 的 Painter
+ * @param modifier 外部传入的 Modifier
+ */
+@Composable
+fun SplashScreen(
+    backgroundPainter: Painter,
+    iconPainter: Painter,
+    modifier: Modifier = Modifier,
+) {
+    val configuration = LocalConfiguration.current
+    val density = LocalDensity.current
+    val screenHeightDp = configuration.screenHeightDp.dp
+    val statusBarHeight = with(density) { WindowInsets.statusBars.getTop(this).toDp() }
+    val availableHeight = screenHeightDp - statusBarHeight
+    val iconTopPadding = statusBarHeight + (availableHeight * 0.25f) - (SplashIconSize / 2)
+    val isDark = isSystemInDarkTheme()
+
+    Box(
+        modifier = modifier.fillMaxSize(),
+    ) {
+        Image(
+            painter = backgroundPainter,
+            contentDescription = null,
+            contentScale = ContentScale.Crop,
+            modifier = Modifier.fillMaxSize(),
+        )
+
+        if (isDark) {
+            Box(
+                modifier = Modifier
+                    .fillMaxSize()
+                    .background(Color.Black.copy(alpha = DarkOverlayAlpha)),
+            )
+        }
+
+        Image(
+            painter = iconPainter,
+            contentDescription = null,
+            modifier = Modifier
+                .align(Alignment.TopCenter)
+                .padding(top = iconTopPadding.coerceAtLeast(statusBarHeight))
+                .size(SplashIconSize),
+        )
+    }
+}