feat(compose): add MaterialTheme.dimensions spacing tokens

Author: criticalAY

AnkiDroid/src/main/java/com/ichi2/compose/theme/Dimensions.kt

@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+// SPDX-FileCopyrightText: 2026 Ashish Yadav <mailtoashish693@gmail.com>
+
+package com.ichi2.compose.theme
+
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.Immutable
+import androidx.compose.runtime.ReadOnlyComposable
+import androidx.compose.runtime.staticCompositionLocalOf
+import androidx.compose.ui.unit.Dp
+import androidx.compose.ui.unit.dp
+
+/**
+ * Semantic spacing tokens for Compose screens, defined by intent rather than exact pixels.
+ * * Access these via [MaterialTheme.dimensions] to keep spacing consistent with
+ * Material 3 colors and typography (e.g., `MaterialTheme.dimensions.screenEdge`).
+ *
+ * @property screenEdge Outer padding between content and the device edge.
+ * @property sectionGap Gap between independent UI sections.
+ * @property itemGap Gap between related items in a row or column.
+ * @property tightGap Fine-grained spacing inside compound elements.
+ * @property microGap Sub-element spacing (e.g., an eyebrow text above a title).
+ */
+@Immutable
+data class Dimensions(
+    val screenEdge: Dp = 24.dp,
+    val sectionGap: Dp = 16.dp,
+    val itemGap: Dp = 12.dp,
+    val tightGap: Dp = 8.dp,
+    val microGap: Dp = 4.dp,
+)
+
+/**
+ * Provides the active [Dimensions] down the Compose tree.
+ * * For cleaner code, read from [MaterialTheme.dimensions] instead of using this directly.
+ * You only need to use this directly when overriding tokens via `CompositionLocalProvider`.
+ */
+val LocalDimensions = staticCompositionLocalOf { Dimensions() }
+
+/**
+ * A handy extension to access spacing tokens the exact same way you access
+ * [MaterialTheme.colorScheme] or [MaterialTheme.typography].
+ */
+val MaterialTheme.dimensions: Dimensions
+    @Composable
+    @ReadOnlyComposable
+    get() = LocalDimensions.current

AnkiDroid/src/main/java/com/ichi2/compose/theme/Theme.kt

@@ -12,6 +12,7 @@ import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.darkColorScheme
 import androidx.compose.material3.lightColorScheme
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.CompositionLocalProvider
 import androidx.compose.runtime.remember
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.graphics.toArgb
@@ -36,7 +37,9 @@ import com.ichi2.anki.R
 fun Theme(content: @Composable () -> Unit) {
     val context = LocalContext.current
     val colorScheme = remember(context) { context.toMaterial3ColorScheme() }
-    MaterialTheme(colorScheme = colorScheme, content = content)
+    CompositionLocalProvider(LocalDimensions provides Dimensions()) {
+        MaterialTheme(colorScheme = colorScheme, content = content)
+    }
 }
 
 @VisibleForTesting