[BottomNavigationView][NavigationRailView] Modifying NavigationBarView to match more to specs and restructuring layout to prepare for expressive changes

Changes:
- minHeight for BottomNavigationView is actually a minimum height, not an exact height; the bar height now wraps content properly
- For BottomNavigationView, bottom item padding now counts from the bottom of the label group instead of from the lowest label baseline. The label TextViews also have a min height of the line height supplied by the provided TextAppearance. This aligns with our m3 specs
- Structural changes in navigation item layouts. Previously the label and the icon were not aware of each other in a FrameLayout and could potentially overlap; this is no longer the case as they are in a LinearLayout
- padding between icon and label is 4dp as per specs
- Centering logic changed to center the icon and label as a group, not separately
PiperOrigin-RevId: 635922505

Author: imhappi

lib/java/com/google/android/material/bottomnavigation/BottomNavigationMenuView.java

@@ -77,7 +77,7 @@ protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
     tempChildWidths.clear();
 
     int parentHeight = MeasureSpec.getSize(heightMeasureSpec);
-    final int heightSpec = MeasureSpec.makeMeasureSpec(parentHeight, MeasureSpec.EXACTLY);
+    final int heightSpec = MeasureSpec.makeMeasureSpec(parentHeight, MeasureSpec.AT_MOST);
 
     if (isShifting(getLabelVisibilityMode(), visibleCount)
         && isItemHorizontalTranslationEnabled()) {
@@ -131,6 +131,7 @@ && isItemHorizontalTranslationEnabled()) {
     }
 
     int totalWidth = 0;
+    int maxHeight = 0;
     for (int i = 0; i < totalCount; i++) {
       final View child = getChildAt(i);
       if (child.getVisibility() == GONE) {
@@ -141,9 +142,10 @@ && isItemHorizontalTranslationEnabled()) {
       ViewGroup.LayoutParams params = child.getLayoutParams();
       params.width = child.getMeasuredWidth();
       totalWidth += child.getMeasuredWidth();
+      maxHeight = Math.max(maxHeight, child.getMeasuredHeight());
     }
 
-    setMeasuredDimension(totalWidth, parentHeight);
+    setMeasuredDimension(totalWidth, Math.max(maxHeight, getSuggestedMinimumHeight()));
   }
 
   @Override

lib/java/com/google/android/material/bottomnavigation/BottomNavigationView.java

@@ -19,7 +19,6 @@
 import com.google.android.material.R;
 
 import static androidx.annotation.RestrictTo.Scope.LIBRARY_GROUP;
-import static java.lang.Math.min;
 
 import android.content.Context;
 import android.os.Build.VERSION;
@@ -168,6 +167,13 @@ public WindowInsetsCompat onApplyWindowInsets(
   protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
     int minHeightSpec = makeMinHeightSpec(heightMeasureSpec);
     super.onMeasure(widthMeasureSpec, minHeightSpec);
+    if (MeasureSpec.getMode(heightMeasureSpec) != MeasureSpec.EXACTLY) {
+      setMeasuredDimension(
+          getMeasuredWidth(),
+          Math.max(
+              getMeasuredHeight(),
+              getSuggestedMinimumHeight() + getPaddingTop() + getPaddingBottom()));
+    }
   }
 
   private int makeMinHeightSpec(int measureSpec) {
@@ -176,7 +182,7 @@ private int makeMinHeightSpec(int measureSpec) {
       minHeight += getPaddingTop() + getPaddingBottom();
 
       return MeasureSpec.makeMeasureSpec(
-          min(MeasureSpec.getSize(measureSpec), minHeight), MeasureSpec.EXACTLY);
+          Math.max(MeasureSpec.getSize(measureSpec), minHeight), MeasureSpec.AT_MOST);
     }
 
     return measureSpec;

lib/java/com/google/android/material/bottomnavigation/res/layout/design_bottom_navigation_item.xml

@@ -15,53 +15,65 @@
   ~ limitations under the License.
   -->
 <merge xmlns:android="http://schemas.android.com/apk/res/android">
-
-  <FrameLayout
-    android:id="@id/navigation_bar_item_icon_container"
+  <LinearLayout
+    android:id="@id/navigation_bar_item_content_container"
     android:layout_width="wrap_content"
     android:layout_height="wrap_content"
-    android:layout_gravity="center_horizontal"
+    android:layout_gravity="top|center_horizontal"
+    android:clipChildren="false"
+    android:duplicateParentState="true"
+    android:gravity="center"
     android:layout_marginTop="@dimen/design_bottom_navigation_margin"
-    android:layout_marginBottom="@dimen/design_bottom_navigation_margin"
-    android:duplicateParentState="true">
-    <View
-      android:id="@id/navigation_bar_item_active_indicator_view"
-      android:layout_width="0dp"
-      android:layout_height="0dp"
-      android:layout_gravity="center" />
-    <ImageView
-      android:id="@id/navigation_bar_item_icon_view"
-      android:layout_width="24dp"
-      android:layout_height="24dp"
+    android:orientation="vertical">
+    <FrameLayout
+      android:id="@id/navigation_bar_item_icon_container"
+      android:layout_width="wrap_content"
+      android:layout_height="wrap_content"
       android:layout_gravity="center"
-      android:contentDescription="@null"
-      android:duplicateParentState="true"/>
-  </FrameLayout>
-  <com.google.android.material.internal.BaselineLayout
+      android:duplicateParentState="true">
+      <View
+        android:id="@id/navigation_bar_item_active_indicator_view"
+        android:layout_width="0dp"
+        android:layout_height="0dp"
+        android:layout_gravity="center" />
+      <ImageView
+        android:id="@id/navigation_bar_item_icon_view"
+        android:layout_width="@dimen/design_bottom_navigation_icon_size"
+        android:layout_height="@dimen/design_bottom_navigation_icon_size"
+        android:layout_gravity="center"
+        android:contentDescription="@null"
+        android:duplicateParentState="true" />
+    </FrameLayout>
+    <com.google.android.material.internal.BaselineLayout
       android:id="@id/navigation_bar_item_labels_group"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
-      android:layout_gravity="bottom|center_horizontal"
-      android:paddingBottom="@dimen/design_bottom_navigation_label_padding"
+      android:paddingBottom="@dimen/m3_bottom_nav_item_padding_bottom"
       android:clipChildren="false"
       android:clipToPadding="false"
+      android:layout_gravity="center"
       android:duplicateParentState="true">
-    <TextView
+      <TextView
         android:id="@id/navigation_bar_item_small_label_view"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:duplicateParentState="true"
         android:ellipsize="end"
         android:maxLines="1"
-        android:textSize="@dimen/design_bottom_navigation_text_size"/>
-    <TextView
+        android:includeFontPadding="false"
+        android:gravity="center_vertical"
+        android:textSize="@dimen/design_bottom_navigation_text_size" />
+      <TextView
         android:id="@id/navigation_bar_item_large_label_view"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:duplicateParentState="true"
         android:ellipsize="end"
         android:maxLines="1"
+        android:gravity="center_vertical"
+        android:includeFontPadding="false"
         android:textSize="@dimen/design_bottom_navigation_active_text_size"
-        android:visibility="invisible"/>
-  </com.google.android.material.internal.BaselineLayout>
+        android:visibility="invisible" />
+    </com.google.android.material.internal.BaselineLayout>
+  </LinearLayout>
 </merge>

lib/java/com/google/android/material/bottomnavigation/res/values/styles.xml

@@ -26,7 +26,8 @@
     <item name="itemIconSize">@dimen/design_bottom_navigation_icon_size</item>
     <item name="labelVisibilityMode">auto</item>
     <item name="itemPaddingTop">@dimen/design_bottom_navigation_margin</item>
-    <item name="itemPaddingBottom">@dimen/design_bottom_navigation_label_padding</item>
+    <item name="itemPaddingBottom">0dp</item>
+    <item name="activeIndicatorLabelPadding">1dp</item>
     <item name="itemActiveIndicatorStyle">@null</item>
     <item name="android:minHeight">@dimen/design_bottom_navigation_height</item>
   </style>
@@ -80,6 +81,7 @@
     <item name="android:minHeight">@dimen/m3_bottom_nav_min_height</item>
     <item name="materialThemeOverlay">@style/ThemeOverlay.Material3.BottomNavigationView</item>
     <item name="shapeAppearance">@style/ShapeAppearance.M3.Comp.NavigationBar.Container.Shape</item>
+    <item name="activeIndicatorLabelPadding">@dimen/m3_navigation_item_active_indicator_label_padding</item>
   </style>
 
   <style name="Widget.Material3.BottomNavigationView" parent="Base.Widget.Material3.BottomNavigationView">

lib/java/com/google/android/material/internal/BaselineLayout.java

@@ -22,14 +22,18 @@
 import android.view.ViewGroup;
 
 /**
- * A simple ViewGroup that aligns all the views inside on a baseline. Note: bottom padding for this
- * view will be measured starting from the baseline.
+ * A simple ViewGroup that aligns all the views inside on a baseline.
+ *
+ * <p>If {@link BaselineLayout#measurePaddingFromBaseline} is true, bottom padding for this view
+ * will be measured starting from the baseline.
  *
  * @hide
  */
 public class BaselineLayout extends ViewGroup {
   private int baseline = -1;
 
+  private boolean measurePaddingFromBaseline;
+
   public BaselineLayout(Context context) {
     super(context, null, 0);
   }
@@ -42,13 +46,19 @@ public BaselineLayout(Context context, AttributeSet attrs, int defStyleAttr) {
     super(context, attrs, defStyleAttr);
   }
 
+  // TODO(b/338647654): We can remove this once navigation rail is updated to current specs
+  public void setMeasurePaddingFromBaseline(boolean measurePaddingFromBaseline) {
+    this.measurePaddingFromBaseline = measurePaddingFromBaseline;
+  }
+
   @Override
   protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
     final int count = getChildCount();
     int maxWidth = 0;
     int maxHeight = 0;
     int maxChildBaseline = -1;
     int maxChildDescent = -1;
+    int maxMeasuredHeight = 0;
     int childState = 0;
 
     for (int i = 0; i < count; i++) {
@@ -58,6 +68,7 @@ protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
       }
 
       measureChild(child, widthMeasureSpec, heightMeasureSpec);
+      maxMeasuredHeight = Math.max(maxMeasuredHeight, child.getMeasuredHeight());
       final int baseline = child.getBaseline();
       if (baseline != -1) {
         maxChildBaseline = Math.max(maxChildBaseline, baseline);
@@ -68,11 +79,15 @@ protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
       childState = View.combineMeasuredStates(childState, child.getMeasuredState());
     }
     if (maxChildBaseline != -1) {
-      maxChildDescent = Math.max(maxChildDescent, getPaddingBottom());
-      maxHeight = Math.max(maxHeight, maxChildBaseline + maxChildDescent);
+      if (measurePaddingFromBaseline) {
+        maxChildDescent = Math.max(maxChildDescent, getPaddingBottom());
+        maxHeight = Math.max(maxHeight, maxChildBaseline + maxChildDescent);
+      }
       this.baseline = maxChildBaseline;
     }
-    maxHeight = Math.max(maxHeight, getSuggestedMinimumHeight());
+    maxHeight = Math.max(
+        measurePaddingFromBaseline ? maxHeight : maxMeasuredHeight + getPaddingBottom(),
+        getSuggestedMinimumHeight());
     maxWidth = Math.max(maxWidth, getSuggestedMinimumWidth());
     setMeasuredDimension(
         View.resolveSizeAndState(maxWidth, widthMeasureSpec, childState),