[List UI Unification] Basic list unification for phones

chrome/android/java/src/org/chromium/chrome/browser/widget/selection/SelectableListLayout.java

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.chrome.browser.widget.selection;
 
 import android.content.Context;
 import android.content.res.Configuration;
 import android.content.res.Resources;
+import android.graphics.Rect;
 import android.graphics.drawable.Drawable;
+import android.support.annotation.VisibleForTesting;
 import android.support.v4.widget.DrawerLayout;
 import android.support.v7.widget.LinearLayoutManager;
 import android.support.v7.widget.RecyclerView;
 import android.support.v7.widget.RecyclerView.Adapter;
 import android.support.v7.widget.RecyclerView.AdapterDataObserver;
+import android.support.v7.widget.RecyclerView.ItemAnimator;
+import android.support.v7.widget.RecyclerView.OnScrollListener;
 import android.support.v7.widget.Toolbar.OnMenuItemClickListener;
 import android.util.AttributeSet;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewStub;
 import android.widget.RelativeLayout;
 import android.widget.TextView;
 
 import org.chromium.base.ApiCompatibilityUtils;
 import org.chromium.chrome.R;
 import org.chromium.chrome.browser.widget.FadingShadow;
 import org.chromium.chrome.browser.widget.FadingShadowView;
 import org.chromium.chrome.browser.widget.LoadingView;
 import org.chromium.chrome.browser.widget.displaystyle.DisplayStyleObserver;
 import org.chromium.chrome.browser.widget.displaystyle.HorizontalDisplayStyle;
 import org.chromium.chrome.browser.widget.displaystyle.UiConfig;
 import org.chromium.chrome.browser.widget.displaystyle.UiConfig.DisplayStyle;
+import org.chromium.chrome.browser.widget.selection.SelectionDelegate.SelectionObserver;
 import org.chromium.ui.base.DeviceFormFactor;
 
+import java.util.List;
+
 import javax.annotation.Nullable;
 
 /**
  * Contains UI elements common to selectable list views: a loading view, empty view, selection
  * toolbar, shadow, and RecyclerView.
  *
  * After the SelectableListLayout is inflated, it should be initialized through calls to
  * #initializeRecyclerView(), #initializeToolbar(), and #initializeEmptyView().
  *
  * @param <E> The type of the selectable items this layout holds.
  */
-public class SelectableListLayout<E> extends RelativeLayout implements DisplayStyleObserver {
+public class SelectableListLayout<E>
+        extends RelativeLayout implements DisplayStyleObserver, SelectionObserver<E> {
+    /**
+     * @param res Resources used to retrieve drawables and dimensions.
+     * @return The default list item lateral margin size in pixels. This value should be used in
+     *         {@link HorizontalDisplayStyle#REGULAR} to hide the lateral shadow and rounded edges
+     *         on items that use the list_item* 9-patches as a background.
+     */
+    public static int getDefaultListItemLateralMarginPx(Resources res) {
+        if (sDefaultListItemLateralMarginPx == null) {
+            Rect listItemShadow = new Rect();
+            ApiCompatibilityUtils.getDrawable(res, R.drawable.card_middle)
+                    .getPadding(listItemShadow);
+            int cardCornerRadius = res.getDimensionPixelSize(R.dimen.list_item_corner_radius);
+
+            assert listItemShadow.left == listItemShadow.right;
+            // A negative margin is used in HorizontalDisplayStyle#REGULAR to hide the lateral
+            // shadow.

[gone, 2017/02/17 01:45:02]

Swap assert and comment to avoid comment sandwich, or move assert under
getPadding() when you pull it out.

[Theresa, 2017/02/17 17:34:28]

I added an extra blank line between the assert and the comment to avoid the
dreaded comment sandwich.

[gone, 2017/02/17 17:57:51]

My sensibilities thank you.

+            sDefaultListItemLateralMarginPx = -(listItemShadow.left + cardCornerRadius);
+        }
+
+        return sDefaultListItemLateralMarginPx;
+    }
+
     private static final int WIDE_DISPLAY_MIN_PADDING_DP = 16;
 
+    private static Integer sDefaultListItemLateralMarginPx;

[gone, 2017/02/17 01:45:02]

maybe use a regular int and -1?

[Theresa, 2017/02/17 17:34:28]

Done.

+
     private Adapter<RecyclerView.ViewHolder> mAdapter;
     private ViewStub mToolbarStub;
     private TextView mEmptyView;
     private LoadingView mLoadingView;
     private RecyclerView mRecyclerView;
+    private ItemAnimator mItemAnimator;
     SelectableListToolbar<E> mToolbar;
+    private FadingShadowView mToolbarShadow;
+
+    private boolean mToolbarPermanentlyHidden;
+    private int mEmptyStringResId;
+    private int mSearchEmptyStringResId;
 
     private UiConfig mUiConfig;
 
     private final AdapterDataObserver mAdapterObserver = new AdapterDataObserver() {
         @Override
         public void onChanged() {
             super.onChanged();
             if (mAdapter.getItemCount() == 0) {
                 mEmptyView.setVisibility(View.VISIBLE);
                 mRecyclerView.setVisibility(View.GONE);
@@ skipping 14 matching lines @@
             updateEmptyViewVisibility();
         }
 
         @Override
         public void onItemRangeRemoved(int positionStart, int itemCount) {
             super.onItemRangeRemoved(positionStart, itemCount);
             updateEmptyViewVisibility();
         }
     };
 
-    /**
-     * Unlike ListView or GridView, RecyclerView does not provide default empty
-     * view implementation. We need to check it ourselves.
-     */
-    private void updateEmptyViewVisibility() {
-        mEmptyView.setVisibility(mAdapter.getItemCount() == 0 ? View.VISIBLE : View.GONE);
-    }
-
     public SelectableListLayout(Context context, AttributeSet attrs) {
         super(context, attrs);
     }
 
     @Override
     protected void onFinishInflate() {
         super.onFinishInflate();
 
         LayoutInflater.from(getContext()).inflate(R.layout.selectable_list_layout, this);
 
@@ skipping 21 matching lines @@
      *                that are displayed within the RecyclerView.
      * @return The RecyclerView itself.
      */
     public RecyclerView initializeRecyclerView(Adapter<RecyclerView.ViewHolder> adapter) {
         mAdapter = adapter;
         mAdapter.registerAdapterDataObserver(mAdapterObserver);
 
         mRecyclerView = (RecyclerView) findViewById(R.id.recycler_view);
         mRecyclerView.setAdapter(mAdapter);
         mRecyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
+
         mRecyclerView.setHasFixedSize(true);
+        mRecyclerView.addOnScrollListener(new OnScrollListener() {
+            @Override
+            public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
+                setToolbarShadowVisibility();
+            }
+        });
+
+        mItemAnimator = mRecyclerView.getItemAnimator();
 
         return mRecyclerView;
     }
 
     /**
      * Initializes the SelectionToolbar.
      *
      * @param toolbarLayoutId The resource id of the toolbar layout. This will be inflated into
      *                        a ViewStub.
      * @param delegate The SelectionDelegate that will inform the toolbar of selection changes.
      * @param titleResId The resource id of the title string. May be 0 if this class shouldn't set
      *                   set a title when the selection is cleared.
      * @param drawerLayout The DrawerLayout whose navigation icon is displayed in this toolbar.
      * @param normalGroupResId The resource id of the menu group to show when a selection isn't
      *                         established.
      * @param selectedGroupResId The resource id of the menu item to show when a selection is
      *                           established.
      * @param normalBackgroundColorResId The resource id of the color to use as the background color
      *                                   when selection is not enabled. If null the default appbar
      *                                   background color will be used.
      * @param hideShadowOnLargeTablets Whether the toolbar shadow should be hidden on large tablets.
      * @param listener The OnMenuItemClickListener to set on the toolbar.
      * @return The initialized SelectionToolbar.
      */
     public SelectableListToolbar<E> initializeToolbar(int toolbarLayoutId,
             SelectionDelegate<E> delegate, int titleResId, @Nullable DrawerLayout drawerLayout,
             int normalGroupResId, int selectedGroupResId,
             @Nullable Integer normalBackgroundColorResId, boolean hideShadowOnLargeTablets,
             @Nullable OnMenuItemClickListener listener) {
-        FadingShadowView shadow = (FadingShadowView) findViewById(R.id.shadow);
-        if (hideShadowOnLargeTablets && DeviceFormFactor.isLargeTablet(getContext())) {
-            shadow.setVisibility(View.GONE);
-        } else {
-            shadow.init(ApiCompatibilityUtils.getColor(getResources(),
-                    R.color.toolbar_shadow_color), FadingShadow.POSITION_TOP);
-        }
-
         mToolbarStub.setLayoutResource(toolbarLayoutId);
         @SuppressWarnings("unchecked")
         SelectableListToolbar<E> toolbar = (SelectableListToolbar<E>) mToolbarStub.inflate();
         mToolbar = toolbar;
         mToolbar.initialize(delegate, titleResId, drawerLayout, normalGroupResId,
                 selectedGroupResId, normalBackgroundColorResId);
 
         if (listener != null) {
             mToolbar.setOnMenuItemClickListener(listener);
         }
 
+        mToolbarShadow = (FadingShadowView) findViewById(R.id.shadow);
+        if (hideShadowOnLargeTablets && DeviceFormFactor.isLargeTablet(getContext())) {
+            mToolbarPermanentlyHidden = true;
+            mToolbarShadow.setVisibility(View.GONE);
+        } else {
+            mToolbarShadow.init(
+                    ApiCompatibilityUtils.getColor(getResources(), R.color.toolbar_shadow_color),
+                    FadingShadow.POSITION_TOP);
+            delegate.addObserver(this);
+            setToolbarShadowVisibility();
+        }
+
         return mToolbar;
     }
 
     /**
      * Initializes the view shown when the selectable list is empty.
      *
      * @param emptyDrawable The Drawable to show when the selectable list is empty.
      * @param emptyStringResId The string to show when the selectable list is empty.
+     * @param searchEmptyStringResId The string to show when the selectable list is empty during
+     *                               a search.
      * @return The {@link TextView} displayed when the list is empty.
      */
-    public TextView initializeEmptyView(Drawable emptyDrawable, int emptyStringResId) {
+    public TextView initializeEmptyView(
+            Drawable emptyDrawable, int emptyStringResId, int searchEmptyStringResId) {
+        mEmptyStringResId = emptyStringResId;
+        mSearchEmptyStringResId = searchEmptyStringResId;
+
         mEmptyView.setCompoundDrawablesWithIntrinsicBounds(null, emptyDrawable, null, null);
-        mEmptyView.setText(emptyStringResId);
+        mEmptyView.setText(mEmptyStringResId);
         return mEmptyView;
     }
 
     /**
-     * @param emptyStringResId The string to show when the selectable list is empty.
-     */
-    public void setEmptyViewText(int emptyStringResId) {
-        mEmptyView.setText(emptyStringResId);
-    }
-
-    /**
      * Called when the view that owns the SelectableListLayout is destroyed.
      */
     public void onDestroyed() {
         mAdapter.unregisterAdapterDataObserver(mAdapterObserver);
+        mToolbar.getSelectionDelegate().removeObserver(this);
     }
 
     /**
      * When this layout has a wide display style, it will be width constrained to
      * {@link UiConfig#WIDE_DISPLAY_STYLE_MIN_WIDTH_DP}. If the current screen width is greater than
      * UiConfig#WIDE_DISPLAY_STYLE_MIN_WIDTH_DP, the SelectableListLayout will be visually centered
      * by adding padding to both sides.
      *
      * This method should be called after the toolbar and RecyclerView are initialized.
      *
@@ skipping 16 matching lines @@
 
     @Override
     public void onDisplayStyleChanged(DisplayStyle newDisplayStyle) {
         int padding = getPaddingForDisplayStyle(newDisplayStyle, getResources());
 
         ApiCompatibilityUtils.setPaddingRelative(mRecyclerView,
                 padding, mRecyclerView.getPaddingTop(),
                 padding, mRecyclerView.getPaddingBottom());
     }
 
+    @Override
+    public void onSelectionStateChange(List<E> selectedItems) {
+        setToolbarShadowVisibility();
+    }
+
+    /**
+     * Called when a search is starting.
+     */
+    public void onStartSearch() {
+        mRecyclerView.setItemAnimator(null);
+        mToolbarShadow.setVisibility(View.VISIBLE);
+        mEmptyView.setText(mSearchEmptyStringResId);
+    }
+
+    /**
+     * Called when a search has ended.
+     */
+    public void onEndSearch() {
+        mRecyclerView.setItemAnimator(mItemAnimator);
+        setToolbarShadowVisibility();
+        mEmptyView.setText(mEmptyStringResId);
+    }
+
     /**
      * @param displayStyle The current display style..
      * @param resources The {@link Resources} used to retrieve configuration and display metrics.
      * @return The lateral padding to use for the current display style.
      */
     public static int getPaddingForDisplayStyle(DisplayStyle displayStyle, Resources resources) {
         int padding = 0;
         if (displayStyle.horizontal == HorizontalDisplayStyle.WIDE) {
             int screenWidthDp = resources.getConfiguration().screenWidthDp;
             float dpToPx = resources.getDisplayMetrics().density;
             padding = (int) (((screenWidthDp - UiConfig.WIDE_DISPLAY_STYLE_MIN_WIDTH_DP) / 2.f)
                     * dpToPx);
             padding = (int) Math.max(WIDE_DISPLAY_MIN_PADDING_DP * dpToPx, padding);
         }
         return padding;
     }
+
+    private void setToolbarShadowVisibility() {
+        if (mToolbarPermanentlyHidden || mToolbar == null || mRecyclerView == null) return;
+
+        boolean showShadow = mRecyclerView.computeVerticalScrollOffset() != 0
+                || mToolbar.isSearching() || mToolbar.getSelectionDelegate().isSelectionEnabled();
+        mToolbarShadow.setVisibility(showShadow ? View.VISIBLE : View.GONE);
+    }
+
+    /**
+     * Unlike ListView or GridView, RecyclerView does not provide default empty
+     * view implementation. We need to check it ourselves.
+     */
+    private void updateEmptyViewVisibility() {
+        mEmptyView.setVisibility(mAdapter.getItemCount() == 0 ? View.VISIBLE : View.GONE);
+    }
+
+    @VisibleForTesting
+    public View getToolbarShadowForTests() {
+        return mToolbarShadow;
+    }
 }