Navigation rails make it easy for users to explore and switch between top-level views in a * single tap. They should be placed at the side edge of large screen devices such as tablets, when * an application has three to seven top-level destinations. * *
The bar contents can be populated by specifying a menu resource file. Each menu item title, * icon and enabled state will be used for displaying navigation rail bar items. Menu items can also * be used for programmatically selecting which destination is currently active. It can be done * using {@code MenuItem#setChecked(true)}. * *
A header view (such as a {@link * com.google.android.material.floatingactionbutton.FloatingActionButton}, logo, etc.) can be added * with the {@code app:headerLayout} attribute or by using {@link #addHeaderView}. * *
* layout resource file: * <com.google.android.material.navigationrail.NavigationRailView * xmlns:android="http://schemas.android.com/apk/res/android" * xmlns:app="http://schema.android.com/apk/res/res-auto" * android:id="@+id/navigation" * android:layout_width="wrap_content" * android:layout_height="match_parent" * app:menu="@menu/my_navigation_items" * app:headerLayout="@layout/my_navigation_rail_fab" /> * * res/menu/my_navigation_items.xml: * <menu xmlns:android="http://schemas.android.com/apk/res/android"> * <item android:id="@+id/action_search" * android:title="@string/menu_search" * android:icon="@drawable/ic_search" /> * <item android:id="@+id/action_settings" * android:title="@string/menu_settings" * android:icon="@drawable/ic_add" /> * <item android:id="@+id/action_navigation" * android:title="@string/menu_navigation" * android:icon="@drawable/ic_action_navigation_menu" /> * </menu> * * res/layout/my_navigation_rail_fab.xml: * <com.google.android.material.floatingactionbutton.FloatingActionButton * xmlns:android="http://schemas.android.com/apk/res/android" * xmlns:app="http://schemas.android.com/apk/res-auto" * android:id="@+id/my_navigation_rail_fab" * android:layout_width="wrap_content" * android:layout_height="wrap_content" * android:contentDescription="@string/my_navigation_rail_fab_content_desc" * app:srcCompat="@drawable/ic_add" /> ** *
For more information, see the component * developer guidance and design guidelines. */ public class NavigationRailView extends NavigationBarView { static final int DEFAULT_MENU_GRAVITY = Gravity.TOP | Gravity.CENTER_HORIZONTAL; static final int COLLAPSED_MAX_ITEM_COUNT = 7; private static final int DEFAULT_HEADER_GRAVITY = Gravity.TOP | Gravity.CENTER_HORIZONTAL; static final int NO_ITEM_MINIMUM_HEIGHT = -1; // These are the values for the cubic bezier curve to mimic the spring curve with a damping // ratio of 0.8 and stiffness value of 380. private static final int EXPAND_DURATION = 500; private static final TimeInterpolator CUBIC_BEZIER_INTERPOLATOR = new PathInterpolator(0.38f, 1.21f, 0.22f, 1.00f); private static final int FADE_DURATION = 100; private final int contentMarginTop; private final int headerMarginBottom; private final int minExpandedWidth; private final int maxExpandedWidth; private final boolean scrollingEnabled; private boolean submenuDividersEnabled; @Nullable private View headerView; @Nullable private Boolean paddingTopSystemWindowInsets = null; @Nullable private Boolean paddingBottomSystemWindowInsets = null; @Nullable private Boolean paddingStartSystemWindowInsets = null; private boolean expanded = false; private int collapsedItemSpacing; private int collapsedItemMinHeight = NO_ITEM_MINIMUM_HEIGHT; @ItemIconGravity private int collapsedIconGravity = ITEM_ICON_GRAVITY_TOP; @ItemGravity private int collapsedItemGravity = ITEM_GRAVITY_TOP_CENTER; private int expandedItemMinHeight; @ItemIconGravity private int expandedIconGravity; @ItemGravity private int expandedItemGravity; private int expandedItemSpacing; private NavigationRailFrameLayout contentContainer; public NavigationRailView(@NonNull Context context) { this(context, null); } public NavigationRailView(@NonNull Context context, @Nullable AttributeSet attrs) { this(context, attrs, R.attr.navigationRailStyle); } public NavigationRailView( @NonNull Context context, @Nullable AttributeSet attrs, int defStyleAttr) { this(context, attrs, defStyleAttr, R.style.Widget_MaterialComponents_NavigationRailView); } public NavigationRailView( @NonNull Context context, @Nullable AttributeSet attrs, int defStyleAttr, int defStyleRes) { super(context, attrs, defStyleAttr, defStyleRes); // Ensure we are using the correctly themed context rather than the context that was passed in. context = getContext(); expandedItemSpacing = getContext() .getResources() .getDimensionPixelSize(R.dimen.m3_navigation_rail_expanded_item_spacing); expandedItemGravity = ITEM_GRAVITY_START_CENTER; expandedIconGravity = ITEM_ICON_GRAVITY_START; /* Custom attributes */ TintTypedArray attributes = ThemeEnforcement.obtainTintedStyledAttributes( context, attrs, R.styleable.NavigationRailView, defStyleAttr, defStyleRes); contentMarginTop = attributes.getDimensionPixelSize( R.styleable.NavigationRailView_contentMarginTop, getResources().getDimensionPixelSize(R.dimen.mtrl_navigation_rail_margin)); headerMarginBottom = attributes.getDimensionPixelSize(R.styleable.NavigationRailView_headerMarginBottom, getResources().getDimensionPixelSize(R.dimen.mtrl_navigation_rail_margin)); scrollingEnabled = attributes.getBoolean(R.styleable.NavigationRailView_scrollingEnabled, false); setSubmenuDividersEnabled(attributes.getBoolean(R.styleable.NavigationRailView_submenuDividersEnabled, false)); addContentContainer(); int headerLayoutRes = attributes.getResourceId(R.styleable.NavigationRailView_headerLayout, 0); if (headerLayoutRes != 0) { addHeaderView(headerLayoutRes); } setMenuGravity( attributes.getInt(R.styleable.NavigationRailView_menuGravity, DEFAULT_MENU_GRAVITY)); int collapsedItemMinHeight = attributes.getDimensionPixelSize( R.styleable.NavigationRailView_itemMinHeight, NO_ITEM_MINIMUM_HEIGHT); int expandedItemMinHeight = attributes.getDimensionPixelSize( R.styleable.NavigationRailView_itemMinHeight, NO_ITEM_MINIMUM_HEIGHT); if (attributes.hasValue(R.styleable.NavigationRailView_collapsedItemMinHeight)) { collapsedItemMinHeight = attributes.getDimensionPixelSize( R.styleable.NavigationRailView_collapsedItemMinHeight, NO_ITEM_MINIMUM_HEIGHT); } if (attributes.hasValue(R.styleable.NavigationRailView_expandedItemMinHeight)) { expandedItemMinHeight = attributes.getDimensionPixelSize( R.styleable.NavigationRailView_expandedItemMinHeight, NO_ITEM_MINIMUM_HEIGHT); } setCollapsedItemMinimumHeight(collapsedItemMinHeight); setExpandedItemMinimumHeight(expandedItemMinHeight); minExpandedWidth = attributes.getDimensionPixelSize( R.styleable.NavigationRailView_expandedMinWidth, context .getResources() .getDimensionPixelSize(R.dimen.m3_navigation_rail_min_expanded_width)); maxExpandedWidth = attributes.getDimensionPixelSize( R.styleable.NavigationRailView_expandedMaxWidth, context .getResources() .getDimensionPixelSize(R.dimen.m3_navigation_rail_max_expanded_width)); if (attributes.hasValue(R.styleable.NavigationRailView_paddingTopSystemWindowInsets)) { paddingTopSystemWindowInsets = attributes.getBoolean(R.styleable.NavigationRailView_paddingTopSystemWindowInsets, false); } if (attributes.hasValue(R.styleable.NavigationRailView_paddingBottomSystemWindowInsets)) { paddingBottomSystemWindowInsets = attributes.getBoolean( R.styleable.NavigationRailView_paddingBottomSystemWindowInsets, false); } if (attributes.hasValue(R.styleable.NavigationRailView_paddingStartSystemWindowInsets)) { paddingStartSystemWindowInsets = attributes.getBoolean( R.styleable.NavigationRailView_paddingStartSystemWindowInsets, false); } int largeFontTopPadding = getResources() .getDimensionPixelOffset(R.dimen.m3_navigation_rail_item_padding_top_with_large_font); int largeFontBottomPadding = getResources() .getDimensionPixelOffset( R.dimen.m3_navigation_rail_item_padding_bottom_with_large_font); float progress = AnimationUtils.lerp(0F, 1F, .3F, 1F, MaterialResources.getFontScale(context) - 1F); float topPadding = AnimationUtils.lerp(getItemPaddingTop(), largeFontTopPadding, progress); float bottomPadding = AnimationUtils.lerp(getItemPaddingBottom(), largeFontBottomPadding, progress); setItemPaddingTop(Math.round(topPadding)); setItemPaddingBottom(Math.round(bottomPadding)); setCollapsedItemSpacing( attributes.getDimensionPixelSize(R.styleable.NavigationRailView_itemSpacing, 0)); setExpanded(attributes.getBoolean(R.styleable.NavigationRailView_expanded, false)); attributes.recycle(); applyWindowInsets(); } private void startTransitionAnimation() { if (!isLaidOut()) { return; } Transition changeBoundsTransition = new ChangeBounds().setDuration(EXPAND_DURATION) .setInterpolator(CUBIC_BEZIER_INTERPOLATOR); Transition labelFadeInTransition = new Fade().setDuration(FADE_DURATION); Transition labelFadeOutTransition = new Fade().setDuration(FADE_DURATION); Transition labelHorizontalMoveTransition = new LabelMoveTransition(); Transition fadingItemsTransition = new Fade().setDuration(FADE_DURATION); // Remove all label groups from being targeted by ChangeBounds as we want a different transition // for it int childCount = getNavigationRailMenuView().getChildCount(); for (int i = 0; i < childCount; i++) { View item = getNavigationRailMenuView().getChildAt(i); if (item instanceof NavigationBarItemView) { // Exclude labels from ChangeBounds transition changeBoundsTransition.excludeTarget(((NavigationBarItemView) item).getLabelGroup(), true); changeBoundsTransition.excludeTarget( ((NavigationBarItemView) item).getExpandedLabelGroup(), true); // If currently expanded, we are fading out the expanded label group and fading in the // collapsed label group if (expanded) { labelFadeOutTransition.addTarget(((NavigationBarItemView) item).getExpandedLabelGroup()); labelFadeInTransition.addTarget(((NavigationBarItemView) item).getLabelGroup()); } else { // Otherwise if we are collapsed, we fade out the collapsed label group and fade in the // expanded labelFadeOutTransition.addTarget(((NavigationBarItemView) item).getLabelGroup()); labelFadeInTransition.addTarget(((NavigationBarItemView) item).getExpandedLabelGroup()); } labelHorizontalMoveTransition.addTarget( ((NavigationBarItemView) item).getExpandedLabelGroup()); } fadingItemsTransition.addTarget(item); } TransitionSet changeBoundsFadeLabelInTransition = new TransitionSet(); changeBoundsFadeLabelInTransition.setOrdering(TransitionSet.ORDERING_TOGETHER); changeBoundsFadeLabelInTransition .addTransition(changeBoundsTransition) .addTransition(labelFadeInTransition) .addTransition(labelHorizontalMoveTransition); // If collapsed, we want to fade in the hidden nav items with the labels if (!expanded) { changeBoundsFadeLabelInTransition.addTransition(fadingItemsTransition); } TransitionSet fadeOutTransitions = new TransitionSet(); fadeOutTransitions.setOrdering(TransitionSet.ORDERING_TOGETHER); fadeOutTransitions.addTransition(labelFadeOutTransition); // If expanded, we want to fade out the nav items to hide with the labels if (expanded) { fadeOutTransitions.addTransition(fadingItemsTransition); } TransitionSet transitionSet = new TransitionSet(); transitionSet.setOrdering(TransitionSet.ORDERING_SEQUENTIAL); transitionSet .addTransition(fadeOutTransitions) .addTransition(changeBoundsFadeLabelInTransition); TransitionManager.beginDelayedTransition((ViewGroup) getParent(), transitionSet); } @Override public void setItemIconGravity(int itemIconGravity) { collapsedIconGravity = itemIconGravity; expandedIconGravity = itemIconGravity; super.setItemIconGravity(itemIconGravity); } @Override public int getItemIconGravity() { return getNavigationRailMenuView().getItemIconGravity(); } @Override public void setItemGravity(int itemGravity) { collapsedItemGravity = itemGravity; expandedItemGravity = itemGravity; super.setItemGravity(itemGravity); } @Override public int getItemGravity() { return getNavigationRailMenuView().getItemGravity(); } private void setExpanded(boolean expanded) { if (this.expanded == expanded) { return; } startTransitionAnimation(); this.expanded = expanded; int iconGravity = collapsedIconGravity; int itemSpacing = collapsedItemSpacing; int itemMinHeight = collapsedItemMinHeight; int itemGravity = collapsedItemGravity; if (expanded) { iconGravity = expandedIconGravity; itemSpacing = expandedItemSpacing; itemMinHeight = expandedItemMinHeight; itemGravity = expandedItemGravity; } getNavigationRailMenuView().setItemGravity(itemGravity); super.setItemIconGravity(iconGravity); getNavigationRailMenuView().setItemSpacing(itemSpacing); getNavigationRailMenuView().setItemMinimumHeight(itemMinHeight); getNavigationRailMenuView().setExpanded(expanded); } /** Expand the navigation rail. */ public void expand() { if (expanded) { return; } setExpanded(true); announceForAccessibility(getResources().getString(R.string.nav_rail_expanded_a11y_label)); } /** Returns whether or not the navigation rail is currently expanded. **/ public boolean isExpanded() { return expanded; } /** Collapse the navigation rail. */ public void collapse() { if (!expanded) { return; } setExpanded(false); announceForAccessibility(getResources().getString(R.string.nav_rail_collapsed_a11y_label)); } private void applyWindowInsets() { ViewUtils.doOnApplyWindowInsets( this, new ViewUtils.OnApplyWindowInsetsListener() { @NonNull @Override public WindowInsetsCompat onApplyWindowInsets( View view, @NonNull WindowInsetsCompat insets, @NonNull RelativePadding initialPadding) { // Apply the top, bottom, and start padding for a start edge aligned // NavigationRailView to dodge the system status/navigation bars and display cutouts Insets systemBarInsets = insets.getInsets(WindowInsetsCompat.Type.systemBars()); Insets displayCutoutInsets = insets.getInsets(WindowInsetsCompat.Type.displayCutout()); if (shouldApplyWindowInsetPadding(paddingTopSystemWindowInsets)) { initialPadding.top += systemBarInsets.top; } if (shouldApplyWindowInsetPadding(paddingBottomSystemWindowInsets)) { initialPadding.bottom += systemBarInsets.bottom; } if (shouldApplyWindowInsetPadding(paddingStartSystemWindowInsets)) { if (ViewUtils.isLayoutRtl(view)) { initialPadding.start += max(systemBarInsets.right, displayCutoutInsets.right); } else { initialPadding.start += max(systemBarInsets.left, displayCutoutInsets.left); } } initialPadding.applyToView(view); return insets; } }); } /** * Whether the top or bottom of this view should be padded in to avoid the system window insets. * *
If the {@code paddingInsetFlag} is set, that value will take precedent. Otherwise, * fitsSystemWindow will be used. */ private boolean shouldApplyWindowInsetPadding(Boolean paddingInsetFlag) { return paddingInsetFlag != null ? paddingInsetFlag : getFitsSystemWindows(); } private int getMaxChildWidth() { int childCount = getNavigationRailMenuView().getChildCount(); int maxChildWidth = 0; for (int i = 0; i < childCount; i++) { View child = getNavigationRailMenuView().getChildAt(i); if (child.getVisibility() != GONE && !(child instanceof NavigationBarDividerView)) { maxChildWidth = max(maxChildWidth, child.getMeasuredWidth()); } } return maxChildWidth; } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { int minWidthSpec = makeMinWidthSpec(widthMeasureSpec); if (expanded) { // Try measuring child with no other restrictions than existing measure spec measureChild(getNavigationRailMenuView(), widthMeasureSpec, heightMeasureSpec); if (headerView != null) { measureChild(headerView, widthMeasureSpec, heightMeasureSpec); } // Measure properly with the max child width minWidthSpec = makeExpandedWidthMeasureSpec(widthMeasureSpec, getMaxChildWidth()); // If the active indicator is match_parent, it should be notified to update its width if (getItemActiveIndicatorExpandedWidth() == MATCH_PARENT) { getNavigationRailMenuView().updateActiveIndicator(MeasureSpec.getSize(minWidthSpec)); } } super.onMeasure(minWidthSpec, heightMeasureSpec); // If the content container is measured to be less than the measured height of the nav rail, // we want to measure it to be exactly the height of the nav rail. if (contentContainer.getMeasuredHeight() < getMeasuredHeight()) { measureChild( contentContainer, minWidthSpec, MeasureSpec.makeMeasureSpec(getMeasuredHeight(), MeasureSpec.EXACTLY)); } } /** * Adds the specified {@link View} layout resource, to appear at the top of the {@link * NavigationRailView}. If the view already has a header view attached to it, it will be removed * first. * * @param layoutRes the unique resource identifier to the layout that should be attached. * @see #addHeaderView(View) * @see #removeHeaderView() * @see #getHeaderView() */ public void addHeaderView(@LayoutRes int layoutRes) { addHeaderView(LayoutInflater.from(getContext()).inflate(layoutRes, this, false)); } /** * Adds the specified {@link View} if any, to appear at the top of the {@link NavigationRailView}. * If the view already has a header view attached to it, it will be removed first. * * @param headerView reference to the {@link View} that should be attached. * @see #addHeaderView(int) * @see #removeHeaderView() * @see #getHeaderView() */ public void addHeaderView(@NonNull View headerView) { removeHeaderView(); this.headerView = headerView; FrameLayout.LayoutParams params = new FrameLayout.LayoutParams(WRAP_CONTENT, WRAP_CONTENT); params.gravity = DEFAULT_HEADER_GRAVITY; params.bottomMargin = headerMarginBottom; contentContainer.addView(headerView, /* index= */ 0, params); } /** * Returns reference to the header view if any, that is currently attached the {@link * NavigationRailView}. * * @see #addHeaderView(int) * @see #addHeaderView(View) * @see #removeHeaderView() */ @Nullable public View getHeaderView() { return headerView; } /** * Removes the current header view if any, from the {@link NavigationRailView}. * * @see #addHeaderView(int) * @see #addHeaderView(View) * @see #getHeaderView() */ public void removeHeaderView() { if (headerView != null) { contentContainer.removeView(headerView); headerView = null; } } /** Sets how destinations in the menu view will be grouped. */ public void setMenuGravity(int gravity) { getNavigationRailMenuView().setMenuGravity(gravity); } /** Gets the current gravity setting for how destinations in the menu view will be grouped. */ public int getMenuGravity() { return getNavigationRailMenuView().getMenuGravity(); } /** Get the current minimum height each item in the navigation rail's menu should be. */ public int getItemMinimumHeight() { return getNavigationRailMenuView().getItemMinimumHeight(); } /** * Set the minimum height each item in the navigation rail's menu should use. * *
If this is unset (-1), each item will be at least as tall as the navigation rail is wide. */ public void setItemMinimumHeight(@Px int minHeight) { collapsedItemMinHeight = minHeight; expandedItemMinHeight = minHeight; NavigationRailMenuView menuView = (NavigationRailMenuView) getMenuView(); menuView.setItemMinimumHeight(minHeight); } /** * Sets the minimum height of a navigation rail menu item when the navigation rail is collapsed. * * @param minHeight the min height of the item when the nav rail is collapsed */ public void setCollapsedItemMinimumHeight(@Px int minHeight) { collapsedItemMinHeight = minHeight; if (!expanded) { ((NavigationRailMenuView) getMenuView()).setItemMinimumHeight(minHeight); } } /** * Gets the minimum height of a navigation rail menu item when the navigation rail is collapsed. */ public int getCollapsedItemMinimumHeight() { return collapsedItemMinHeight; } /** * Sets the minimum height of a navigation rail menu item when the navigation rail is expanded. * * @param minHeight the min height of the item when the nav rail is collapsed */ public void setExpandedItemMinimumHeight(@Px int minHeight) { expandedItemMinHeight = minHeight; if (expanded) { ((NavigationRailMenuView) getMenuView()).setItemMinimumHeight(minHeight); } } /** * Gets the minimum height of a navigation rail menu item when the navigation rail is expanded. */ public int getExpandedItemMinimumHeight() { return expandedItemMinHeight; } /** * Set whether or not to enable the dividers which go between each subgroup in the menu. */ public void setSubmenuDividersEnabled(boolean submenuDividersEnabled) { if (this.submenuDividersEnabled == submenuDividersEnabled) { return; } this.submenuDividersEnabled = submenuDividersEnabled; getNavigationRailMenuView().setSubmenuDividersEnabled(submenuDividersEnabled); } /** * Get whether or not to enable the dividers which go between each subgroup in the menu. */ public boolean getSubmenuDividersEnabled() { return submenuDividersEnabled; } /** * Set the padding in between the navigation rail menu items. */ public void setItemSpacing(@Px int itemSpacing) { this.collapsedItemSpacing = itemSpacing; this.expandedItemSpacing = itemSpacing; getNavigationRailMenuView().setItemSpacing(itemSpacing); } /** * Sets the padding in between the navigation rail menu items when the navigation rail is * collapsed. * * @param itemSpacing the desired item spacing in between the items when the nav rail is collapsed */ public void setCollapsedItemSpacing(@Px int itemSpacing) { this.collapsedItemSpacing = itemSpacing; if (!expanded) { getNavigationRailMenuView().setItemSpacing(itemSpacing); } } /** Get the current padding in between the navigation rail menu items. */ public int getItemSpacing() { return getNavigationRailMenuView().getItemSpacing(); } @Override public int getMaxItemCount() { return NO_MAX_ITEM_LIMIT; } /** @hide */ @RestrictTo(LIBRARY_GROUP) @Override public int getCollapsedMaxItemCount() { return COLLAPSED_MAX_ITEM_COUNT; } private NavigationRailMenuView getNavigationRailMenuView() { return (NavigationRailMenuView) getMenuView(); } /** @hide */ @RestrictTo(LIBRARY_GROUP) @Override @NonNull protected NavigationRailMenuView createNavigationBarMenuView(@NonNull Context context) { return new NavigationRailMenuView(context); } private int makeMinWidthSpec(int measureSpec) { int minWidth = getSuggestedMinimumWidth(); if (MeasureSpec.getMode(measureSpec) != MeasureSpec.EXACTLY && minWidth > 0) { minWidth += getPaddingLeft() + getPaddingRight(); return MeasureSpec.makeMeasureSpec( min(MeasureSpec.getSize(measureSpec), minWidth), MeasureSpec.EXACTLY); } return measureSpec; } private int makeExpandedWidthMeasureSpec(int measureSpec, int measuredWidth) { int minWidth = min(minExpandedWidth, MeasureSpec.getSize(measureSpec)); if (MeasureSpec.getMode(measureSpec) != MeasureSpec.EXACTLY) { int newWidth = max(measuredWidth, minWidth); // Also take into account header view max if (headerView != null) { newWidth = max(newWidth, headerView.getMeasuredWidth()); } newWidth = max(getSuggestedMinimumWidth(), min(newWidth, maxExpandedWidth)); return MeasureSpec.makeMeasureSpec(newWidth, MeasureSpec.EXACTLY); } return measureSpec; } @Override protected boolean isSubMenuSupported() { return true; } private void addContentContainer() { View menuView = (View) getMenuView(); contentContainer = new NavigationRailFrameLayout(getContext()); contentContainer.setPaddingTop(contentMarginTop); contentContainer.setScrollingEnabled(scrollingEnabled); contentContainer.setClipChildren(false); contentContainer.setLayoutParams(new FrameLayout.LayoutParams(MATCH_PARENT, MATCH_PARENT)); menuView.setLayoutParams(new FrameLayout.LayoutParams(WRAP_CONTENT, WRAP_CONTENT)); contentContainer.addView(menuView); if (!scrollingEnabled) { addView(contentContainer); return; } ScrollView scrollView = new ScrollView(getContext()); scrollView.setVerticalScrollBarEnabled(false); scrollView.addView(contentContainer); scrollView.setLayoutParams(new FrameLayout.LayoutParams(MATCH_PARENT, MATCH_PARENT)); addView(scrollView); } /** @hide */ @RestrictTo(LIBRARY_GROUP) @Override public boolean shouldAddMenuView() { return true; } @SuppressLint("ClickableViewAccessibility") @Override public boolean onTouchEvent(@NonNull MotionEvent event) { super.onTouchEvent(event); // Consume all events to avoid views under the NavigationRailView from receiving touch events. return true; } }