Add a chip widget for the new Download Home UI.

This adds the complete MVC structure for a generic horizontal list of
chip views for filter selection.  This will be first used by the new
Download Home UI.

BUG=839489

Screenshot of widget placed in UI: https://drive.google.com/open?id=1Em7em1jg-GnEdyoGLwHUezfgryuJ-cja

Change-Id: I6a7f8a29280c5aeaf01c7be86c15f3fb64ba0288
Reviewed-on: https://chromium-review.googlesource.com/1042813Reviewed-by: Ted Choc <tedchoc@chromium.org>
Commit-Queue: David Trainor <dtrainor@chromium.org>
Cr-Commit-Position: refs/heads/master@{#559224}

chrome/android/java/res/drawable/chip_bg.xml

+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright 2018 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.
+-->
+
+<!-- TODO(crbug.com/839489): Update based on specs. -->
+<shape xmlns:android="http://schemas.android.com/apk/res/android">
+    <solid android:color="@color/google_grey_300" />
+    <stroke android:width="2dp" android:color="@color/google_blue_300" />
+    <corners android:radius="3dp" />
+    <padding android:left="3dp" android:top="3dp" android:right="3dp" android:bottom="3dp" />
+</shape>
\ No newline at end of file

chrome/android/java/res/layout/chip.xml

+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright 2018 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.
+-->
+
+<!-- TODO(crbug.com/839489): Update values based on specs. -->
+<org.chromium.chrome.browser.download.home.filter.chips.ChipView
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="wrap_content"
+    android:layout_height="wrap_content"
+    android:minHeight="32dp"
+    android:gravity="center"
+    android:maxLines="1"
+    android:paddingStart="13dp"
+    android:paddingEnd="13dp"
+    android:textAlignment="center"
+    android:clickable="true"
+    android:textAppearance="@style/BlueButtonText2"
+    android:background="@drawable/chip_bg" />
\ No newline at end of file

chrome/android/java/res/values/dimens.xml

@@ -563,4 +563,7 @@
     <item type="dimen" name="dialog_fixed_width_minor">100%</item>
     <item type="dimen" name="dialog_fixed_height_major">100%</item>
     <item type="dimen" name="dialog_fixed_height_minor">100%</item>
+
+    <!-- Chip list dimensions -->
+    <dimen name="chip_list_padding">2.5dp</dimen>
 </resources>

chrome/android/java/src/org/chromium/chrome/browser/download/home/filter/FilterChipsProvider.java

+// Copyright 2018 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.download.home.filter;
+
+import org.chromium.base.ObserverList;
+import org.chromium.chrome.R;
+import org.chromium.chrome.browser.download.home.filter.Filters.FilterType;
+import org.chromium.chrome.browser.download.home.filter.chips.Chip;
+import org.chromium.chrome.browser.download.home.filter.chips.ChipsProvider;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * A {@link ChipsProvider} implementation that wraps a subset of {@link Filters} to be used as a
+ * chip selector for filtering downloads.
+ * TODO(dtrainor): Hook in as an observer to the download list data source.
+ */
+public class FilterChipsProvider implements ChipsProvider {
+    private static final int INVALID_INDEX = -1;
+
+    private final ObserverList<Observer> mObservers = new ObserverList<ChipsProvider.Observer>();
+    private final List<Chip> mSortedChips = new ArrayList<>();
+
+    /** Builds a new FilterChipsBackend. */
+    public FilterChipsProvider() {
+        Chip noneChip = new Chip(Filters.NONE, R.string.download_manager_ui_all_downloads,
+                R.string.download_manager_ui_all_downloads, R.drawable.ic_play_arrow_white_24dp,
+                () -> onChipSelected(Filters.NONE));
+        Chip videosChip = new Chip(Filters.VIDEOS, R.string.download_manager_ui_video,
+                R.string.download_manager_ui_video, R.drawable.ic_play_arrow_white_24dp,
+                () -> onChipSelected(Filters.VIDEOS));
+        Chip musicChip = new Chip(Filters.MUSIC, R.string.download_manager_ui_audio,
+                R.string.download_manager_ui_audio, R.drawable.ic_play_arrow_white_24dp,
+                () -> onChipSelected(Filters.MUSIC));
+        Chip imagesChip = new Chip(Filters.IMAGES, R.string.download_manager_ui_images,
+                R.string.download_manager_ui_images, R.drawable.ic_play_arrow_white_24dp,
+                () -> onChipSelected(Filters.IMAGES));
+        Chip sitesChip = new Chip(Filters.SITES, R.string.download_manager_ui_pages,
+                R.string.download_manager_ui_pages, R.drawable.ic_play_arrow_white_24dp,
+                () -> onChipSelected(Filters.SITES));
+        Chip otherChip = new Chip(Filters.OTHER, R.string.download_manager_ui_other,
+                R.string.download_manager_ui_other, R.drawable.ic_play_arrow_white_24dp,
+                () -> onChipSelected(Filters.OTHER));
+
+        mSortedChips.add(noneChip);
+        mSortedChips.add(videosChip);
+        mSortedChips.add(musicChip);
+        mSortedChips.add(imagesChip);
+        mSortedChips.add(sitesChip);
+        mSortedChips.add(otherChip);
+    }
+
+    /**
+     * Sets whether or not a filter is enabled.
+     * @param type    The type of filter to enable.
+     * @param enabled Whether or not that filter is enabled.
+     */
+    public void setFilterEnabled(@FilterType int type, boolean enabled) {
+        int chipIndex = getChipIndex(type);
+        if (chipIndex == INVALID_INDEX) return;
+        Chip chip = mSortedChips.get(chipIndex);
+
+        if (enabled == chip.enabled) return;
+        chip.enabled = enabled;
+        for (Observer observer : mObservers) observer.onChipChanged(chipIndex, chip);
+    }
+
+    /**
+     * Sets the filter that is currently selected.
+     * @param type The type of filter to select.
+     */
+    public void setFilterSelected(@FilterType int type) {
+        for (int i = 0; i < mSortedChips.size(); i++) {
+            Chip chip = mSortedChips.get(i);
+            boolean willSelect = chip.id == type;
+
+            // Early out if we're already selecting the appropriate Chip type.
+            if (chip.selected && willSelect) return;
+            if (chip.selected == willSelect) continue;
+            chip.selected = willSelect;
+
+            for (Observer observer : mObservers) observer.onChipChanged(i, chip);
+        }
+    }
+
+    // ChipsProvider implementation.
+    @Override
+    public void addObserver(Observer observer) {
+        mObservers.addObserver(observer);
+    }
+
+    @Override
+    public void removeObserver(Observer observer) {
+        mObservers.removeObserver(observer);
+    }
+
+    @Override
+    public List<Chip> getChips() {
+        return mSortedChips;
+    }
+
+    private void onChipSelected(int id) {
+        setFilterSelected(id);
+        // TODO(dtrainor): Notify external sources.
+    }
+
+    private int getChipIndex(@FilterType int type) {
+        for (int i = 0; i < mSortedChips.size(); i++) {
+            if (mSortedChips.get(i).id == type) return i;
+        }
+
+        return INVALID_INDEX;
+    }
+}
\ No newline at end of file

chrome/android/java/src/org/chromium/chrome/browser/download/home/filter/Filters.java

+// Copyright 2018 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.download.home.filter;
+
+import android.support.annotation.IntDef;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
+/** A list of possible filter types on offlined items. */
+public interface Filters {
+    @Retention(RetentionPolicy.SOURCE)
+    @IntDef({NONE, VIDEOS, MUSIC, IMAGES, SITES, OTHER})
+    public @interface FilterType {}
+    public static final int NONE = 0;
+    public static final int VIDEOS = 1;
+    public static final int MUSIC = 2;
+    public static final int IMAGES = 3;
+    public static final int SITES = 4;
+    public static final int OTHER = 5;
+}
\ No newline at end of file

chrome/android/java/src/org/chromium/chrome/browser/download/home/filter/chips/Chip.java

+// Copyright 2018 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.download.home.filter.chips;
+
+import android.support.annotation.DrawableRes;
+import android.support.annotation.StringRes;
+
+/**
+ * A generic visual representation of a Chip. Most of the visuals are immutable, but the selection
+ * and enable states are not.
+ */
+public class Chip {
+    /** An id used to identify this chip. */
+    public final int id;
+
+    /** The resource id for the text to show in the chip. */
+    public final @StringRes int text;
+
+    /** The resource id for the accessibility text to use for the chip. */
+    public final @StringRes int contentDescription;
+
+    /** The resource id for the icon to use in the chip. */
+    public final @DrawableRes int icon;
+
+    /** The {@link Runnable} to trigger when this chip is selected by the UI. */
+    public final Runnable chipSelectedListener;
+
+    /** Whether or not this Chip is enabled. */
+    public boolean enabled;
+
+    /** Whether or not this Chip is selected. */
+    public boolean selected;
+
+    /** Builds a new {@link Chip} instance.  These properties cannot be changed. */
+    public Chip(int id, @StringRes int text, @StringRes int contentDescription,
+            @DrawableRes int icon, Runnable chipSelectedListener) {
+        this.id = id;
+        this.text = text;
+        this.contentDescription = contentDescription;
+        this.icon = icon;
+        this.chipSelectedListener = chipSelectedListener;
+    }
+}
\ No newline at end of file

chrome/android/java/src/org/chromium/chrome/browser/download/home/filter/chips/ChipView.java

+// Copyright 2018 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.download.home.filter.chips;
+
+import android.content.Context;
+import android.content.res.ColorStateList;
+import android.graphics.drawable.Drawable;
+import android.support.annotation.DrawableRes;
+import android.support.v4.graphics.drawable.DrawableCompat;
+import android.support.v7.widget.AppCompatTextView;
+import android.util.AttributeSet;
+
+import org.chromium.base.ApiCompatibilityUtils;
+
+/**
+ * A {@link AppCompatTextView} that visually represents a {@link Chip} in a chip list.  The way to
+ * get a properly set up {@link ChipView} with the proper properties would be to inflate
+ * R.layout.chip.
+ */
+public class ChipView extends AppCompatTextView {
+    public ChipView(Context context, AttributeSet attrs) {
+        super(context, attrs);
+    }
+
+    /**
+     * Used to effectively set the start compound drawable on the {@link TextView}.  Currently there
+     * is no compat method to handle setting the {@link ColorStateList} for compound drawables.
+     * @param icon The drawable id that represents the icon to use in the chip.
+     */
+    public void setChipIcon(@DrawableRes int icon) {
+        Drawable drawable =
+                DrawableCompat.wrap(ApiCompatibilityUtils.getDrawable(getResources(), icon));
+
+        ColorStateList textColor = getTextColors();
+        if (textColor != null) DrawableCompat.setTintList(drawable.mutate(), textColor);
+        ApiCompatibilityUtils.setCompoundDrawablesRelativeWithIntrinsicBounds(
+                this, drawable, null, null, null);
+    }
+}
\ No newline at end of file

chrome/android/java/src/org/chromium/chrome/browser/download/home/filter/chips/ChipsCoordinator.java

+// Copyright 2018 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.download.home.filter.chips;
+
+import android.content.Context;
+import android.graphics.Rect;
+import android.support.v7.widget.LinearLayoutManager;
+import android.support.v7.widget.RecyclerView;
+import android.support.v7.widget.RecyclerView.ItemDecoration;
+import android.support.v7.widget.RecyclerView.State;
+import android.view.View;
+
+import org.chromium.chrome.R;
+import org.chromium.chrome.browser.modelutil.RecyclerViewAdapter;
+import org.chromium.chrome.browser.modelutil.RecyclerViewAdapter.ViewBinder;
+import org.chromium.chrome.browser.modelutil.RecyclerViewModelChangeProcessor;
+
+/**
+ * The coordinator responsible for managing a list of chips.  To get the {@link View} that
+ * represents this coordinator use {@link #getView()}.
+ */
+public class ChipsCoordinator implements ChipsProvider.Observer {
+    private final ChipsProvider mProvider;
+    private final ChipsModel mModel;
+    private final RecyclerViewModelChangeProcessor<ChipsModel, ChipsViewBinder.ChipsViewHolder>
+            mModelChangeProcessor;
+    private final RecyclerView mView;
+
+    /**
+     * Builds and initializes this coordinator, including all sub-components.
+     * @param context The {@link Context} to use to grab all of the resources.
+     * @param provider The source for the underlying Chip state.
+     */
+    public ChipsCoordinator(Context context, ChipsProvider provider) {
+        assert context != null;
+        assert provider != null;
+
+        mProvider = provider;
+
+        // Build the underlying components.
+        mModel = new ChipsModel();
+        mView = createView(context);
+        ViewBinder<ChipsModel, ChipsViewBinder.ChipsViewHolder> viewBinder = new ChipsViewBinder();
+        RecyclerViewAdapter<ChipsModel, ChipsViewBinder.ChipsViewHolder> adapter =
+                new RecyclerViewAdapter<>(mModel, viewBinder);
+        mModelChangeProcessor =
+                new RecyclerViewModelChangeProcessor<ChipsModel, ChipsViewBinder.ChipsViewHolder>(
+                        adapter);
+
+        mView.setAdapter(adapter);
+        adapter.setViewBinder(viewBinder);
+        mModel.addObserver(mModelChangeProcessor);
+
+        mProvider.addObserver(this);
+        mModel.setChips(mProvider.getChips());
+    }
+
+    /**
+     * Destroys the coordinator.  This should be called when the coordinator is no longer in use.
+     * The coordinator should not be used after that point.
+     */
+    public void destroy() {
+        mProvider.removeObserver(this);
+    }
+
+    /** @return The {@link View} that represents this coordinator. */
+    public View getView() {
+        return mView;
+    }
+
+    // ChipsProvider.Observer implementation.
+    @Override
+    public void onChipChanged(int position, Chip chip) {
+        mModel.updateChip(position, chip);
+        mModel.setChips(mProvider.getChips());
+    }
+
+    private static RecyclerView createView(Context context) {
+        RecyclerView view = new RecyclerView(context);
+        view.setLayoutManager(
+                new LinearLayoutManager(context, LinearLayoutManager.HORIZONTAL, false));
+        view.addItemDecoration(new SpaceItemDecoration(context));
+        view.getItemAnimator().setChangeDuration(0);
+        return view;
+    }
+
+    private static class SpaceItemDecoration extends ItemDecoration {
+        private final int mPaddingPx;
+
+        public SpaceItemDecoration(Context context) {
+            mPaddingPx = (int) context.getResources().getDimension(R.dimen.chip_list_padding);
+        }
+
+        @Override
+        public void getItemOffsets(Rect outRect, View view, RecyclerView parent, State state) {
+            int position = parent.getChildAdapterPosition(view);
+            boolean isFirst = position == 0;
+            boolean isLast = position == parent.getAdapter().getItemCount() - 1;
+
+            outRect.left = isFirst ? 2 * mPaddingPx : mPaddingPx;
+            outRect.right = isLast ? 2 * mPaddingPx : mPaddingPx;
+        }
+    }
+}
\ No newline at end of file

chrome/android/java/src/org/chromium/chrome/browser/download/home/filter/chips/ChipsModel.java

+// Copyright 2018 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.download.home.filter.chips;
+
+import org.chromium.chrome.browser.modelutil.ListObservable;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * A model that holds a list of chips to visually represent in the UI.
+ * TODO(dtrainor): Move to SimpleListObservable once that is supported.
+ */
+class ChipsModel extends ListObservable {
+    private final List<Chip> mChips = new ArrayList<>();
+
+    // ListObservable implementation.
+    @Override
+    public int getItemCount() {
+        return mChips.size();
+    }
+
+    /**
+     * Populates the model with a list of {@link Chip}s.  The list of chips is copied but the
+     * internal {@link Chip} objects are not.
+     * @param chips The new list of {@link Chip}s to store in the model.
+     */
+    public void setChips(List<Chip> chips) {
+        if (chips.size() == mChips.size()) {
+            // Avoid complete list rebuilds for the case where the Chip count is the same.
+            mChips.clear();
+            mChips.addAll(chips);
+            notifyItemRangeChanged(0, mChips.size(), null);
+        } else {
+            if (!mChips.isEmpty()) {
+                int size = mChips.size();
+                mChips.clear();
+                notifyItemRangeRemoved(0, size);
+            }
+
+            if (!chips.isEmpty()) {
+                mChips.addAll(chips);
+                notifyItemRangeInserted(0, mChips.size());
+            }
+        }
+    }
+
+    /** Updates an individual item in the list of Chips. */
+    public void updateChip(int position, Chip chip) {
+        assert position >= 0 && position < mChips.size();
+        mChips.set(position, chip);
+        notifyItemRangeChanged(position, 1, null);
+    }
+
+    /**
+     * @param position The position of the {@link Chip} in the list of chips to return.
+     * @return The {@link Chip} stored at {@code position} in the list of chips.
+     */
+    public Chip getItemAt(int position) {
+        assert position >= 0 && position < mChips.size();
+        return mChips.get(position);
+    }
+}
\ No newline at end of file

chrome/android/java/src/org/chromium/chrome/browser/download/home/filter/chips/ChipsProvider.java

+// Copyright 2018 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.download.home.filter.chips;
+
+import java.util.List;
+
+/** A source of Chips meant to be visually represented by a {@link ChipCoordinator}. */
+public interface ChipsProvider {
+    /** Interface to be called a Chip's state changes. */
+    interface Observer {
+        /** Called whenever the list of Chips changes. */
+        void onChipChanged(int position, Chip chip);
+    }
+
+    /** Adds an {@link Observer} to be notified of Chip state changes. */
+    void addObserver(Observer observer);
+
+    /** Removes an {@link Observer} to be notified of Chip state changes. */
+    void removeObserver(Observer observer);
+
+    /** @return A list of {@link Chip} objects. */
+    List<Chip> getChips();
+}
\ No newline at end of file

chrome/android/java/src/org/chromium/chrome/browser/download/home/filter/chips/ChipsViewBinder.java

+// Copyright 2018 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.download.home.filter.chips;
+
+import android.support.v7.widget.RecyclerView.ViewHolder;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+
+import org.chromium.chrome.R;
+import org.chromium.chrome.browser.modelutil.RecyclerViewAdapter.ViewBinder;
+
+/** Responsible for binding the {@link ChipsModel} to {@link ViewHolder}s in the RecyclerView. */
+class ChipsViewBinder implements ViewBinder<ChipsModel, ChipsViewBinder.ChipsViewHolder> {
+    /** The {@link ViewHolder} responsible for reflecting a {@link Chip} to a {@link ChipView}. */
+    public static class ChipsViewHolder extends ViewHolder {
+        /**
+         * Builds a ChipsViewHolder around a specific {@link ChipView}.
+         * @param itemView
+         */
+        public ChipsViewHolder(View itemView) {
+            super(itemView);
+
+            assert itemView instanceof ChipView;
+        }
+
+        /**
+         * Pushes the properties of {@code chip} to {@code itemView}.
+         * @param chip The {@link Chip} to visually reflect in the stored {@link ChipView}.
+         */
+        public void bind(Chip chip) {
+            ChipView view = (ChipView) itemView;
+
+            view.setEnabled(chip.enabled);
+            view.setSelected(chip.selected);
+            view.setOnClickListener(v -> chip.chipSelectedListener.run());
+
+            view.setChipIcon(chip.icon);
+            view.setText(chip.text);
+            view.setContentDescription(view.getContext().getText(chip.contentDescription));
+        }
+    }
+
+    // ViewBinder implementation.
+    @Override
+    public ChipsViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
+        return new ChipsViewHolder(
+                LayoutInflater.from(parent.getContext()).inflate(R.layout.chip, null));
+    }
+
+    @Override
+    public void onBindViewHolder(ChipsModel model, ChipsViewHolder holder, int position) {
+        holder.bind(model.getItemAt(position));
+    }
+}
\ No newline at end of file

chrome/android/java_sources.gni

@@ -416,6 +416,14 @@ chrome_java_sources = [
   "java/src/org/chromium/chrome/browser/download/OMADownloadHandler.java",
   "java/src/org/chromium/chrome/browser/download/SystemDownloadNotifier.java",
   "java/src/org/chromium/chrome/browser/download/SystemDownloadNotifier2.java",
+  "java/src/org/chromium/chrome/browser/download/home/filter/Filters.java",
+  "java/src/org/chromium/chrome/browser/download/home/filter/FilterChipsProvider.java",
+  "java/src/org/chromium/chrome/browser/download/home/filter/chips/Chip.java",
+  "java/src/org/chromium/chrome/browser/download/home/filter/chips/ChipsCoordinator.java",
+  "java/src/org/chromium/chrome/browser/download/home/filter/chips/ChipsModel.java",
+  "java/src/org/chromium/chrome/browser/download/home/filter/chips/ChipsProvider.java",
+  "java/src/org/chromium/chrome/browser/download/home/filter/chips/ChipsViewBinder.java",
+  "java/src/org/chromium/chrome/browser/download/home/filter/chips/ChipView.java",
   "java/src/org/chromium/chrome/browser/download/items/OfflineContentAggregatorFactory.java",
   "java/src/org/chromium/chrome/browser/download/items/OfflineContentAggregatorNotificationBridgeUi.java",
   "java/src/org/chromium/chrome/browser/download/items/OfflineContentAggregatorNotificationBridgeUiFactory.java",