[NavigationRail] Fixed issue where top padding was not respected if menu gravity was center or bottom in certain scenarios

PiperOrigin-RevId: 675656279

Author: imhappi

lib/java/com/google/android/material/navigation/NavigationBarView.java

@@ -38,6 +38,7 @@
 import android.view.Menu;
 import android.view.MenuInflater;
 import android.view.MenuItem;
+import android.view.ViewGroup;
 import android.widget.FrameLayout;
 import androidx.annotation.AttrRes;
 import androidx.annotation.DimenRes;
@@ -400,7 +401,9 @@ public NavigationBarView(
 
     attributes.recycle();
 
-    addView(menuView);
+    if (!shouldAddMenuView()) {
+      addView(menuView);
+    }
 
     this.menu.setCallback(
         new MenuBuilder.Callback() {
@@ -418,6 +421,18 @@ public void onMenuModeChange(MenuBuilder menu) {}
         });
   }
 
+  /**
+   * Whether or not to add the menu view; if true, the menu view is added to the NavigationBarView
+   * in the constructor. Otherwise, the menu view should be added to the NavigationBarView as a
+   * descendant view somewhere else.
+   *
+   * @hide
+   */
+  @RestrictTo(LIBRARY_GROUP)
+  public boolean shouldAddMenuView() {
+    return false;
+  }
+
   @Override
   protected void onAttachedToWindow() {
     super.onAttachedToWindow();
@@ -476,6 +491,14 @@ public MenuView getMenuView() {
     return menuView;
   }
 
+  /**
+   * Returns the {@link android.view.ViewGroup} associated with the navigation bar menu.
+   */
+  @NonNull
+  public ViewGroup getMenuViewGroup() {
+    return menuView;
+  }
+
   /**
    * Inflate a menu resource into this navigation view.
    *

lib/java/com/google/android/material/navigationrail/NavigationRailFrameLayout.java

@@ -0,0 +1,96 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.android.material.navigationrail;
+
+import static androidx.annotation.RestrictTo.Scope.LIBRARY_GROUP;
+import static java.lang.Math.max;
+
+import android.content.Context;
+import android.view.View;
+import android.widget.FrameLayout;
+import androidx.annotation.NonNull;
+import androidx.annotation.RestrictTo;
+
+/**
+ * A {@link FrameLayout} implementation that lays out its children such that there is no vertical
+ * overlap.
+ *
+ * @hide
+ */
+@RestrictTo(LIBRARY_GROUP)
+public class NavigationRailFrameLayout extends FrameLayout {
+
+  int paddingTop = 0;
+
+  public NavigationRailFrameLayout(@NonNull Context context) {
+    super(context);
+  }
+
+  public void setPaddingTop(int paddingTop) {
+    this.paddingTop = paddingTop;
+  }
+
+  @Override
+  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
+    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
+    int childCount = getChildCount();
+    int totalHeaderHeight = 0;
+    View menuView = getChildAt(0);
+    int menuHeightSpec = heightMeasureSpec;
+
+    // If there's more than one child, the header should be first
+    if (childCount > 1) {
+      // Measure header
+      View headerView = getChildAt(0);
+      measureChild(headerView, widthMeasureSpec, heightMeasureSpec);
+      LayoutParams headerLp = (LayoutParams) headerView.getLayoutParams();
+      totalHeaderHeight =
+          headerView.getMeasuredHeight() + headerLp.bottomMargin + headerLp.topMargin;
+      int maxMenuHeight = getMeasuredHeight() - totalHeaderHeight - paddingTop;
+
+      // Measure menu
+      menuView = getChildAt(1);
+      menuHeightSpec = MeasureSpec.makeMeasureSpec(maxMenuHeight, MeasureSpec.AT_MOST);
+    }
+    LayoutParams menuLp = (LayoutParams) menuView.getLayoutParams();
+    measureChild(menuView, widthMeasureSpec, menuHeightSpec);
+    int totalMenuHeight = menuView.getMeasuredHeight() + menuLp.bottomMargin + menuLp.topMargin;
+    int totalHeight = max(getMeasuredHeight(), paddingTop + totalHeaderHeight + totalMenuHeight);
+
+    setMeasuredDimension(getMeasuredWidth(), totalHeight);
+  }
+
+  @Override
+  protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
+    super.onLayout(changed, left, top, right, bottom);
+    // We want to leave everything placed as is in the FrameLayout, but bumped down if it's
+    // overlaying with something
+    int childCount = getChildCount();
+    int y = paddingTop;
+    for (int i = 0; i < childCount; i++) {
+      View child = getChildAt(i);
+      FrameLayout.LayoutParams lp = (LayoutParams) child.getLayoutParams();
+      y = max(y, child.getTop());
+      y += lp.topMargin;
+      child.layout(
+          child.getLeft(),
+          y,
+          child.getRight(),
+          y + child.getMeasuredHeight());
+      y += child.getMeasuredHeight() + lp.bottomMargin;
+    }
+  }
+}

lib/java/com/google/android/material/navigationrail/NavigationRailMenuView.java

@@ -25,7 +25,6 @@
 import static java.lang.Math.min;
 
 import android.content.Context;
-import android.view.Gravity;
 import android.view.View;
 import android.widget.FrameLayout;
 import androidx.annotation.NonNull;
@@ -218,8 +217,4 @@ public void setItemSpacing(@Px int spacing) {
   public int getItemSpacing() {
     return this.itemSpacing;
   }
-
-  boolean isTopGravity() {
-    return (layoutParams.gravity & Gravity.VERTICAL_GRAVITY_MASK) == Gravity.TOP;
-  }
 }

lib/java/com/google/android/material/navigationrail/NavigationRailView.java

@@ -18,6 +18,7 @@
 
 import com.google.android.material.R;
 
+import static android.view.ViewGroup.LayoutParams.MATCH_PARENT;
 import static android.view.ViewGroup.LayoutParams.WRAP_CONTENT;
 import static androidx.annotation.RestrictTo.Scope.LIBRARY_GROUP;
 import static java.lang.Math.max;
@@ -127,6 +128,7 @@ public class NavigationRailView extends NavigationBarView {
   @ItemIconGravity private int expandedIconGravity;
   @ItemGravity private int expandedItemGravity;
   private int expandedItemSpacing;
+  private NavigationRailFrameLayout contentContainer;
 
   public NavigationRailView(@NonNull Context context) {
     this(context, null);
@@ -178,6 +180,8 @@ public NavigationRailView(
         attributes.getDimensionPixelSize(R.styleable.NavigationRailView_headerMarginBottom,
             getResources().getDimensionPixelSize(R.dimen.mtrl_navigation_rail_margin));
 
+    addContentContainer();
+
     int headerLayoutRes = attributes.getResourceId(R.styleable.NavigationRailView_headerLayout, 0);
     if (headerLayoutRes != 0) {
       addHeaderView(headerLayoutRes);
@@ -337,37 +341,10 @@ protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
       minWidthSpec = makeExpandedWidthMeasureSpec(widthMeasureSpec, getMaxChildWidth());
     }
     super.onMeasure(minWidthSpec, heightMeasureSpec);
-    if (isHeaderViewVisible()) {
-      int maxMenuHeight = getMeasuredHeight() - headerView.getMeasuredHeight() - contentMarginTop
-          - headerMarginBottom;
-      int menuHeightSpec = MeasureSpec.makeMeasureSpec(maxMenuHeight, MeasureSpec.AT_MOST);
-      measureChild(getNavigationRailMenuView(), minWidthSpec, menuHeightSpec);
-    }
-  }
-
-  @Override
-  protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
-    super.onLayout(changed, left, top, right, bottom);
-
-    NavigationRailMenuView menuView = getNavigationRailMenuView();
-    int offsetY = 0;
-    if (isHeaderViewVisible()) {
-      int usedTop = headerView.getBottom() + headerMarginBottom;
-      int menuTop = menuView.getTop();
-      if (menuTop < usedTop) {
-        offsetY = usedTop - menuTop;
-      }
-    } else if (menuView.isTopGravity()) {
-      offsetY = contentMarginTop;
-    }
-
-    if (offsetY > 0) {
-      menuView.layout(
-          menuView.getLeft(),
-          menuView.getTop() + offsetY,
-          menuView.getRight(),
-          menuView.getBottom() + offsetY);
-    }
+    measureChild(
+        contentContainer,
+        minWidthSpec,
+        MeasureSpec.makeMeasureSpec(getMeasuredHeight(), MeasureSpec.EXACTLY));
   }
 
   /**
@@ -399,8 +376,8 @@ public void addHeaderView(@NonNull View headerView) {
 
     FrameLayout.LayoutParams params = new FrameLayout.LayoutParams(WRAP_CONTENT, WRAP_CONTENT);
     params.gravity = DEFAULT_HEADER_GRAVITY;
-    params.topMargin = contentMarginTop;
-    addView(headerView, /* index= */ 0, params);
+    params.bottomMargin = headerMarginBottom;
+    contentContainer.addView(headerView, /* index= */ 0, params);
   }
 
   /**
@@ -425,7 +402,7 @@ public View getHeaderView() {
    */
   public void removeHeaderView() {
     if (headerView != null) {
-      removeView(headerView);
+      contentContainer.removeView(headerView);
       headerView = null;
     }
   }
@@ -527,7 +504,20 @@ private int makeExpandedWidthMeasureSpec(int measureSpec, int measuredWidth) {
     return measureSpec;
   }
 
-  private boolean isHeaderViewVisible() {
-    return headerView != null && headerView.getVisibility() != View.GONE;
+  private void addContentContainer() {
+    View menuView = (View) getMenuView();
+    contentContainer = new NavigationRailFrameLayout(getContext());
+    contentContainer.setPaddingTop(contentMarginTop);
+    contentContainer.setLayoutParams(new FrameLayout.LayoutParams(MATCH_PARENT, MATCH_PARENT));
+    menuView.setLayoutParams(new FrameLayout.LayoutParams(WRAP_CONTENT, WRAP_CONTENT));
+    contentContainer.addView(menuView);
+    addView(contentContainer);
+  }
+
+  /** @hide */
+  @RestrictTo(LIBRARY_GROUP)
+  @Override
+  public boolean shouldAddMenuView() {
+    return true;
   }
 }