[Home] Add a bottom navigation bar for the BottomSheet

chrome/android/java/src/org/chromium/chrome/browser/widget/BottomSheetContentController.java

Index: chrome/android/java/src/org/chromium/chrome/browser/widget/BottomSheetContentController.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/widget/BottomSheetContentController.java b/chrome/android/java/src/org/chromium/chrome/browser/widget/BottomSheetContentController.java
new file mode 100644
index 0000000000000000000000000000000000000000..69a7938297ece1dbfd24e38cc334ef84b084c663
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+++ b/chrome/android/java/src/org/chromium/chrome/browser/widget/BottomSheetContentController.java
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+// Copyright 2017 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;
+
+import android.content.Context;
+import android.content.res.Resources;
+import android.support.design.internal.BottomNavigationItemView;
+import android.support.design.internal.BottomNavigationMenuView;
+import android.support.design.widget.BottomNavigationView;
+import android.support.design.widget.BottomNavigationView.OnNavigationItemSelectedListener;
+import android.util.AttributeSet;
+import android.view.MenuItem;
+import android.view.View;
+
+import org.chromium.chrome.R;
+import org.chromium.chrome.browser.util.MathUtils;
+import org.chromium.ui.widget.Toast;
+
+import java.lang.reflect.Field;
+
+/**
+ * Displays and controls a {@link BottomNavigationView} fixed to the bottom of the
+ * {@link BottomSheet}.
+ */
+public class BottomSheetContentController extends BottomNavigationView
+        implements BottomSheetObserver, OnNavigationItemSelectedListener {
+    private BottomSheet mBottomSheet;
+    private float mDistanceBelowToolbarPx;
+
+    public BottomSheetContentController(Context context, AttributeSet atts) {
+        super(context, atts);
+    }
+
+    /**
+     * Initializes the {@link BottomSheetContentController}.
+     * @param bottomSheet The {@link BottomSheet} associated with this bottom nav.
+     * @param controlContainerHeight The height of the control container in px.
+     */
+    public void init(BottomSheet bottomSheet, int controlContainerHeight) {
+        mBottomSheet = bottomSheet;
+        mBottomSheet.addObserver(this);
+
+        Resources res = getContext().getResources();
+        mDistanceBelowToolbarPx = controlContainerHeight
+                + res.getDimensionPixelOffset(R.dimen.bottom_nav_space_from_toolbar);
+
+        setOnNavigationItemSelectedListener(this);
+        disableShiftingMode();
+    }
+
+    @Override
+    public boolean onNavigationItemSelected(MenuItem item) {
+        Toast.makeText(getContext(), "Not implemented", Toast.LENGTH_SHORT).show();
+        return false;
+    }
+
+    @Override
+    public void onTransitionPeekToHalf(float transitionFraction) {
+        float offsetY = (mBottomSheet.getMinOffset() - mBottomSheet.getSheetOffsetFromBottom())
+                + mDistanceBelowToolbarPx;
+        setTranslationY((int) Math.max(offsetY, 0f));
+        setVisibility(MathUtils.areFloatsEqual(transitionFraction, 0f) ? View.GONE : View.VISIBLE);
+    }
+
+    @Override
+    public void onSheetOpened() {}
+
+    @Override
+    public void onSheetClosed() {}
+
+    @Override
+    public void onLoadUrl(String url) {}
+
+    @Override
+    public void onSheetOffsetChanged(float heightFraction) {}
+
+    // TODO(twellington): remove this once the support library is updated to allow disabling
+    //                    shifting mode or determines shifting mode based on the width of the
+    //                    child views.
+    private void disableShiftingMode() {
+        BottomNavigationMenuView menuView = (BottomNavigationMenuView) getChildAt(0);
+        try {
+            Field shiftingMode = menuView.getClass().getDeclaredField("mShiftingMode");
+            shiftingMode.setAccessible(true);
+            shiftingMode.setBoolean(menuView, false);
+            shiftingMode.setAccessible(false);
+            for (int i = 0; i < menuView.getChildCount(); i++) {
+                BottomNavigationItemView item = (BottomNavigationItemView) menuView.getChildAt(i);
+                item.setShiftingMode(false);
+                // Set the checked value so that the view will be updated.
+                item.setChecked(item.getItemData().isChecked());
+            }
+        } catch (NoSuchFieldException | IllegalAccessException e) {
+            // Do nothing if reflection fails.
+        }
+    }
+}