leanback/widget/AbstractMediaItemPresenter.java

/*
 * Copyright (C) 2016 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 android.support.v17.leanback.widget;


import android.animation.ValueAnimator;
import android.content.Context;
import android.graphics.Color;
import android.graphics.Rect;
import android.support.v17.leanback.R;
import android.support.v4.view.ViewCompat;
import android.util.TypedValue;
import android.view.ContextThemeWrapper;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.animation.DecelerateInterpolator;
import android.widget.TextView;
import android.widget.ViewFlipper;

import java.util.ArrayList;
import java.util.List;

/**
 * Abstract {@link Presenter} class for rendering media items in a playlist format.
 * Media item data provided for this presenter can implement the interface
 * {@link MultiActionsProvider}, if the media rows wish to contain custom actions.
 * Media items in the playlist are arranged as a vertical list with each row holding each media
 * item's details provided by the user of this class and a set of optional custom actions.
 * Each media item's details and actions are separately focusable.
 * The appearance of each one of the media row components can be controlled through setting
 * theme's attributes.
 * Each media item row provides a view flipper for switching between different views depending on
 * the playback state.
 * A default layout is provided by this presenter for rendering different playback states, or a
 * custom layout can be provided by the user by overriding the
 * playbackMediaItemNumberViewFlipperLayout attribute in the currently specified theme.
 * Subclasses should also override {@link #getMediaPlayState(Object)} to provide the current play
 * state of their media item model in case they wish to use different views depending on the
 * playback state.
 * The presenter can optionally provide line separators between media rows by setting
 * {@link #setHasMediaRowSeparator(boolean)} to true.
 * <p>
 *     Subclasses must override {@link #onBindMediaDetails} to implement their media item model
 *     data binding to each row view.
 * </p>
 * <p>
 *     The {@link OnItemViewClickedListener} and {@link OnItemViewSelectedListener}
 *     can be used in the same fashion to handle selection or click events on either of
 *     media details or each individual action views.
 * </p>
 * <p>
 *     {@link AbstractMediaListHeaderPresenter} can be used in conjunction with this presenter in
 *     order to display a playlist with a header view.
 * </p>
 */
public abstract class AbstractMediaItemPresenter extends RowPresenter {

    /**
     * Different playback states of a media item
     */

    /**
     * Indicating that the media item is currently neither playing nor paused.
     */
    public static final int PLAY_STATE_INITIAL = 0;
    /**
     * Indicating that the media item is currently paused.
     */
    public static final int PLAY_STATE_PAUSED = 1;
    /**
     * Indicating that the media item is currently playing
     */
    public static final int PLAY_STATE_PLAYING = 2;

    final static Rect sTempRect = new Rect();
    private int mBackgroundColor = Color.TRANSPARENT;
    private boolean mBackgroundColorSet;
    private boolean mMediaRowSeparator;
    private int mThemeId;

    private Presenter mMediaItemActionPresenter = new MediaItemActionPresenter();

    /**
     * Constructor used for creating an abstract media item presenter.
     */
    public AbstractMediaItemPresenter() {
        this(0);
    }

    /**
     * Constructor used for creating an abstract media item presenter.
     * @param themeId The resource id of the theme that defines attributes controlling the
     *                appearance of different widgets in a media item row.
     */
    public AbstractMediaItemPresenter(int themeId) {
        mThemeId = themeId;
        setHeaderPresenter(null);
    }

    /**
     * Sets the theme used to style a media item row components.
     * @param themeId The resource id of the theme that defines attributes controlling the
     *                appearance of different widgets in a media item row.
     */
    public void setThemeId(int themeId) {
        mThemeId = themeId;
    }

    /**
     * Return The resource id of the theme that defines attributes controlling the appearance of
     * different widgets in a media item row.
     *
     * @return The resource id of the theme that defines attributes controlling the appearance of
     * different widgets in a media item row.
     */
    public int getThemeId() {
        return mThemeId;
    }

    /**
     * Sets the action presenter rendering each optional custom action within each media item row.
     * @param actionPresenter the presenter to be used for rendering a media item row actions.
     */
    public void setActionPresenter(Presenter actionPresenter) {
        mMediaItemActionPresenter = actionPresenter;
    }

    /**
     * Return the presenter used to render a media item row actions.
     *
     * @return the presenter used to render a media item row actions.
     */
    public Presenter getActionPresenter() {
        return mMediaItemActionPresenter;
    }

    /**
     * The ViewHolder for the {@link AbstractMediaItemPresenter}. It references different views
     * that place different meta-data corresponding to a media item details, actions, selector,
     * listeners, and presenters,
     */
    public static class ViewHolder extends RowPresenter.ViewHolder {

        private final View mMediaRowView;
        private final View mSelectorView;
        private final View mMediaItemDetailsView;
        private final ViewFlipper mMediaItemNumberViewFlipper;
        private final TextView mMediaItemNumberView;
        private final View mMediaItemPausedView;

        private final View mMediaItemPlayingView;
        private final TextView mMediaItemNameView;
        private final TextView mMediaItemDurationView;
        private final View mMediaItemRowSeparator;
        private final ViewGroup mMediaItemActionsContainer;
        private final List<Presenter.ViewHolder> mActionViewHolders;
        private MultiActionsProvider.MultiAction[] mMediaItemRowActions;
        AbstractMediaItemPresenter mRowPresenter;
        private ValueAnimator mFocusViewAnimator;

        public ViewHolder(View view) {
            super(view);
            mSelectorView = view.findViewById(R.id.mediaRowSelector);
            mMediaRowView  = view.findViewById(R.id.mediaItemRow);
            mMediaItemDetailsView = view.findViewById(R.id.mediaItemDetails);
            mMediaItemNameView = (TextView) view.findViewById(R.id.mediaItemName);
            mMediaItemDurationView = (TextView) view.findViewById(R.id.mediaItemDuration);
            mMediaItemRowSeparator = view.findViewById(R.id.mediaRowSeparator);
            mMediaItemActionsContainer = (ViewGroup) view.findViewById(
                    R.id.mediaItemActionsContainer);
            mActionViewHolders = new ArrayList<Presenter.ViewHolder>();
            getMediaItemDetailsView().setOnClickListener(new View.OnClickListener(){
                @Override
                public void onClick(View view) {
                    if (getOnItemViewClickedListener() != null) {
                        getOnItemViewClickedListener().onItemClicked(null, null,
                                ViewHolder.this, getRowObject());
                    }
                }
            });
            getMediaItemDetailsView().setOnFocusChangeListener(new View.OnFocusChangeListener() {
                @Override
                public void onFocusChange(View view, boolean hasFocus) {
                    mFocusViewAnimator = updateSelector(mSelectorView, view, mFocusViewAnimator,
                            true);
                }
            });
            mMediaItemNumberViewFlipper =
                    (ViewFlipper) view.findViewById(R.id.mediaItemNumberViewFlipper);

            TypedValue typedValue = new TypedValue();
            boolean found = view.getContext().getTheme().resolveAttribute(
                    R.attr.playbackMediaItemNumberViewFlipperLayout, typedValue, true);
            View mergeView = LayoutInflater.from(view.getContext()).
                    inflate(found ? typedValue.resourceId :
                            R.layout.lb_media_item_number_view_flipper,
                            mMediaItemNumberViewFlipper, true);

            mMediaItemNumberView = (TextView) mergeView.findViewById(R.id.initial);
            mMediaItemPausedView = mergeView.findViewById(R.id.paused);
            mMediaItemPlayingView = mergeView.findViewById(R.id.playing);
        }

        /**
         * Binds the actions in a media item row object to their views. This consists of creating
         * (or reusing the existing) action view holders, and populating them with the actions'
         * icons.
         */
        public void onBindRowActions() {
            for (int i = getMediaItemActionsContainer().getChildCount() - 1;
                 i >= mActionViewHolders.size(); i--) {
                getMediaItemActionsContainer().removeViewAt(i);
                mActionViewHolders.remove(i);
            }
            mMediaItemRowActions = null;

            Object rowObject = getRowObject();
            final MultiActionsProvider.MultiAction[] actionList;
            if (rowObject instanceof MultiActionsProvider) {
                actionList = ((MultiActionsProvider) rowObject).getActions();
            } else {
                return;
            }
            Presenter actionPresenter = mRowPresenter.getActionPresenter();
            if (actionPresenter == null) {
                return;
            }

            mMediaItemRowActions = actionList;
            for (int i = mActionViewHolders.size(); i < actionList.length; i++) {
                final int actionIndex = i;
                final Presenter.ViewHolder actionViewHolder = actionPresenter.
                        onCreateViewHolder(getMediaItemActionsContainer());
                getMediaItemActionsContainer().addView(actionViewHolder.view);
                mActionViewHolders.add(actionViewHolder);
                actionViewHolder.view.setOnFocusChangeListener(new View.OnFocusChangeListener() {
                    @Override
                    public void onFocusChange(View view, boolean hasFocus) {
                        mFocusViewAnimator = updateSelector(mSelectorView, view,
                                mFocusViewAnimator, false);
                    }
                });
                actionViewHolder.view.setOnClickListener(
                        new View.OnClickListener() {
                            @Override
                            public void onClick(View view) {
                                if (getOnItemViewClickedListener() != null) {
                                    getOnItemViewClickedListener().onItemClicked(
                                            actionViewHolder, mMediaItemRowActions[actionIndex],
                                            ViewHolder.this, getRowObject());
                                }
                            }
                        });
            }

            if (mMediaItemActionsContainer != null) {
                for (int i = 0; i < actionList.length; i++) {
                    Presenter.ViewHolder avh = mActionViewHolders.get(i);
                    actionPresenter.onUnbindViewHolder(avh);
                    actionPresenter.onBindViewHolder(avh, mMediaItemRowActions[i]);
                }
            }

        }

        int findActionIndex(MultiActionsProvider.MultiAction action) {
            if (mMediaItemRowActions != null) {
                for (int i = 0; i < mMediaItemRowActions.length; i++) {
                    if (mMediaItemRowActions[i] == action) {
                        return i;
                    }
                }
            }
            return -1;
        }

        /**
         * Notifies an action has changed in this media row and the UI needs to be updated
         * @param action The action whose state has changed
         */
        public void notifyActionChanged(MultiActionsProvider.MultiAction action) {
            Presenter actionPresenter = mRowPresenter.getActionPresenter();
            if (actionPresenter == null) {
                return;
            }
            int actionIndex = findActionIndex(action);
            if (actionIndex >= 0) {
                Presenter.ViewHolder actionViewHolder = mActionViewHolders.get(actionIndex);
                actionPresenter.onUnbindViewHolder(actionViewHolder);
                actionPresenter.onBindViewHolder(actionViewHolder, action);
            }
        }

        /**
         * Notifies the content of the media item details in a row has changed and triggers updating
         * the UI. This causes {@link #onBindMediaDetails(ViewHolder, Object)}
         * on the user's provided presenter to be called back, allowing them to update UI
         * accordingly.
         */
        public void notifyDetailsChanged() {
            mRowPresenter.onUnbindMediaDetails(this);
            mRowPresenter.onBindMediaDetails(this, getRowObject());
        }

        /**
         * Notifies the playback state of the media item row has changed. This in turn triggers
         * updating of the UI for that media item row if corresponding views are specified for each
         * playback state.
         * By default, 3 views are provided for each playback state, or these views can be provided
         * by the user.
         */
        public void notifyPlayStateChanged() {
            mRowPresenter.onBindMediaPlayState(this);
        }

        /**
         * @return The SelectorView responsible for highlighting the in-focus view within each
         * media item row
         */
        public View getSelectorView() {
            return mSelectorView;
        }

        /**
         * @return The FlipperView responsible for flipping between different media item number
         * views depending on the playback state
         */
        public ViewFlipper getMediaItemNumberViewFlipper() {
            return mMediaItemNumberViewFlipper;
        }

        /**
         * @return The TextView responsible for rendering the media item number.
         * This view is rendered when the media item row is neither playing nor paused.
         */
        public TextView getMediaItemNumberView() {
            return mMediaItemNumberView;
        }

        /**
         * @return The view rendered when the media item row is paused.
         */
        public View getMediaItemPausedView() {
            return mMediaItemPausedView;
        }

        /**
         * @return The view rendered when the media item row is playing.
         */
        public View getMediaItemPlayingView() {
            return mMediaItemPlayingView;
        }


        /**
         * Flips to the view at index 'position'. This position corresponds to the index of a
         * particular view within the ViewFlipper layout specified for the MediaItemNumberView
         * (see playbackMediaItemNumberViewFlipperLayout attribute).
         * @param position The index of the child view to display.
         */
        public void setSelectedMediaItemNumberView(int position) {
            if (position >= 0 & position < mMediaItemNumberViewFlipper.getChildCount()) {
                mMediaItemNumberViewFlipper.setDisplayedChild(position);
            }
        }
        /**
         * Returns the view displayed when the media item is neither playing nor paused,
         * corresponding to the playback state of PLAY_STATE_INITIAL.
         * @return The TextView responsible for rendering the media item name.
         */
        public TextView getMediaItemNameView() {
            return mMediaItemNameView;
        }

        /**
         * @return The TextView responsible for rendering the media item duration
         */
        public TextView getMediaItemDurationView() {
            return mMediaItemDurationView;
        }

        /**
         * @return The view container of media item details
         */
        public View getMediaItemDetailsView() {
            return mMediaItemDetailsView;
        }

        /**
         * @return The view responsible for rendering the separator line between media rows
         */
        public View getMediaItemRowSeparator() {
            return mMediaItemRowSeparator;
        }

        /**
         * @return The view containing the set of custom actions
         */
        public ViewGroup getMediaItemActionsContainer() {
            return mMediaItemActionsContainer;
        }

        /**
         * @return Array of MultiActions displayed for this media item row
         */
        public MultiActionsProvider.MultiAction[] getMediaItemRowActions() {
            return mMediaItemRowActions;
        }
    }

    @Override
    protected RowPresenter.ViewHolder createRowViewHolder(ViewGroup parent) {
        Context context = parent.getContext();
        if (mThemeId != 0) {
            context = new ContextThemeWrapper(context, mThemeId);
        }
        View view = LayoutInflater.from(context).
                inflate(R.layout.lb_row_media_item, parent, false);
        final ViewHolder vh = new ViewHolder(view);
        vh.mRowPresenter = this;
        if (mBackgroundColorSet) {
            vh.mMediaRowView.setBackgroundColor(mBackgroundColor);
        }
        return vh;
    }

    @Override
    public boolean isUsingDefaultSelectEffect() {
        return false;
    }

    @Override
    protected boolean isClippingChildren() {
        return true;
    }

    @Override
    protected void onBindRowViewHolder(RowPresenter.ViewHolder vh, Object item) {
        super.onBindRowViewHolder(vh, item);

        final ViewHolder mvh = (ViewHolder) vh;

        onBindRowActions(mvh);

        mvh.getMediaItemRowSeparator().setVisibility(hasMediaRowSeparator() ? View.VISIBLE :
                View.GONE);

        onBindMediaPlayState(mvh);
        onBindMediaDetails((ViewHolder) vh, item);
    }

    /**
     * Binds the given media item object action to the given ViewHolder's action views.
     * @param vh ViewHolder for the media item.
     */
    protected void onBindRowActions(ViewHolder vh) {
        vh.onBindRowActions();
    }

    /**
     * Sets the background color for the row views within the playlist.
     * If this is not set, a default color, defaultBrandColor, from theme is used.
     * This defaultBrandColor defaults to android:attr/colorPrimary on v21, if it's specified.
     * @param color The ARGB color used to set as the media list background color.
     */
    public void setBackgroundColor(int color) {
        mBackgroundColorSet = true;
        mBackgroundColor = color;
    }

    /**
     * Specifies whether a line separator should be used between media item rows.
     * @param hasSeparator true if a separator should be displayed, false otherwise.
     */
    public void setHasMediaRowSeparator(boolean hasSeparator) {
        mMediaRowSeparator = hasSeparator;
    }

    public boolean hasMediaRowSeparator() {
        return mMediaRowSeparator;
    }
    /**
     * Binds the media item details to their views provided by the
     * {@link AbstractMediaItemPresenter}.
     * This method is to be overridden by the users of this presenter.
     * The subclasses of this presenter can access and bind individual views for either of the
     * media item number, name, or duration (depending on whichever views are visible according to
     * the providing theme attributes), by calling {@link ViewHolder#getMediaItemNumberView()},
     * {@link ViewHolder#getMediaItemNameView()}, and {@link ViewHolder#getMediaItemDurationView()},
     * on the {@link ViewHolder} provided as the argument {@code vh} of this presenter.
     *
     * @param vh The ViewHolder for this {@link AbstractMediaItemPresenter}.
     * @param item The media item row object being presented.
     */
    protected abstract void onBindMediaDetails(ViewHolder vh, Object item);

    /**
     * Unbinds the media item details from their views provided by the
     * {@link AbstractMediaItemPresenter}.
     * This method can be overridden by the subclasses of this presenter if required.
     * @param vh ViewHolder to unbind from.
     */
    protected void onUnbindMediaDetails(ViewHolder vh) {
    }

    /**
     * Binds the media item number view to the appropriate play state view of the media item.
     * The play state of the media item is extracted by calling {@link #getMediaPlayState(Object)} for
     * the media item embedded within this view.
     * This method triggers updating of the playback state UI if corresponding views are specified
     * for the current playback state.
     * By default, 3 views are provided for each playback state, or these views can be provided
     * by the user.
     */
    public void onBindMediaPlayState(ViewHolder vh) {
        int childIndex = calculateMediaItemNumberFlipperIndex(vh);
        if (childIndex != -1 && vh.mMediaItemNumberViewFlipper.getDisplayedChild() != childIndex) {
            vh.mMediaItemNumberViewFlipper.setDisplayedChild(childIndex);
        }
    }

    static int calculateMediaItemNumberFlipperIndex(ViewHolder vh) {
        int childIndex = -1;
        int newPlayState = vh.mRowPresenter.getMediaPlayState(vh.getRowObject());
        switch (newPlayState) {
            case PLAY_STATE_INITIAL:
                childIndex = (vh.mMediaItemNumberView == null) ? -1 :
                        vh.mMediaItemNumberViewFlipper.indexOfChild(vh.mMediaItemNumberView);
                break;
            case PLAY_STATE_PAUSED:
                childIndex = (vh.mMediaItemPausedView == null) ? -1 :
                        vh.mMediaItemNumberViewFlipper.indexOfChild(vh.mMediaItemPausedView);
                break;
            case PLAY_STATE_PLAYING:
                childIndex = (vh.mMediaItemPlayingView == null) ? -1 :
                        vh.mMediaItemNumberViewFlipper.indexOfChild(vh.mMediaItemPlayingView);
        }
        return childIndex;
    }

    /**
     * Called when the given ViewHolder wants to unbind the play state view.
     * @param vh The ViewHolder to unbind from.
     */
    public void onUnbindMediaPlayState(ViewHolder vh) {
    }

    /**
     * Returns the current play state of the given media item. By default, this method returns
     * PLAY_STATE_INITIAL which causes the media item number
     * {@link ViewHolder#getMediaItemNameView()} to be displayed for different
     * playback states. Users of this class should override this method in order to provide the
     * play state of their custom media item data model.
     * @param item The media item
     * @return The current play state of this media item
     */
    protected int getMediaPlayState(Object item) {
        return PLAY_STATE_INITIAL;
    }
    /**
     * Each media item row can have multiple focusable elements; the details on the left and a set
     * of optional custom actions on the right.
     * The selector is a highlight that moves to highlight to cover whichever views is in focus.
     *
     * @param selectorView the selector view used to highlight an individual element within a row.
     * @param focusChangedView The component within the media row whose focus got changed.
     * @param layoutAnimator the ValueAnimator producing animation frames for the selector's width
     *                       and x-translation, generated by this method and stored for the each
     *                       {@link ViewHolder}.
     * @param isDetails Whether the changed-focused view is for a media item details (true) or
     *                  an action (false).
     */
    private static ValueAnimator updateSelector(final View selectorView,
            View focusChangedView, ValueAnimator layoutAnimator, boolean isDetails) {
        int animationDuration = focusChangedView.getContext().getResources()
                .getInteger(android.R.integer.config_shortAnimTime);
        DecelerateInterpolator interpolator = new DecelerateInterpolator();

        int layoutDirection = ViewCompat.getLayoutDirection(selectorView);
        if (!focusChangedView.hasFocus()) {
            // if neither of the details or action views are in focus (ie. another row is in focus),
            // animate the selector out.
            selectorView.animate().cancel();
            selectorView.animate().alpha(0f).setDuration(animationDuration)
                    .setInterpolator(interpolator).start();
            // keep existing layout animator
            return layoutAnimator;
        } else {
            // cancel existing layout animator
            if (layoutAnimator != null) {
                layoutAnimator.cancel();
                layoutAnimator = null;
            }
            float currentAlpha = selectorView.getAlpha();
            selectorView.animate().alpha(1f).setDuration(animationDuration)
                    .setInterpolator(interpolator).start();

            final ViewGroup.MarginLayoutParams lp = (ViewGroup.MarginLayoutParams)
                    selectorView.getLayoutParams();
            ViewGroup rootView = (ViewGroup) selectorView.getParent();
            sTempRect.set(0, 0, focusChangedView.getWidth(), focusChangedView.getHeight());
            rootView.offsetDescendantRectToMyCoords(focusChangedView, sTempRect);
            if (isDetails) {
                if (layoutDirection == View.LAYOUT_DIRECTION_RTL ) {
                    sTempRect.right += rootView.getHeight();
                    sTempRect.left -= rootView.getHeight() / 2;
                } else {
                    sTempRect.left -= rootView.getHeight();
                    sTempRect.right += rootView.getHeight() / 2;
                }
            }
            final int targetLeft = sTempRect.left;
            final int targetWidth = sTempRect.width();
            final float deltaWidth = lp.width - targetWidth;
            final float deltaLeft = lp.leftMargin - targetLeft;

            if (deltaLeft == 0f && deltaWidth == 0f)
            {
                // no change needed
            } else if (currentAlpha == 0f) {
                // change selector to the proper width and marginLeft without animation.
                lp.width = targetWidth;
                lp.leftMargin = targetLeft;
                selectorView.requestLayout();
            } else {
                // animate the selector to the proper width and marginLeft.
                layoutAnimator = ValueAnimator.ofFloat(0f, 1f);
                layoutAnimator.setDuration(animationDuration);
                layoutAnimator.setInterpolator(interpolator);

                layoutAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
                    @Override
                    public void onAnimationUpdate(ValueAnimator valueAnimator) {
                        // Set width to the proper width for this animation step.
                        float fractionToEnd = 1f - valueAnimator.getAnimatedFraction();
                        lp.leftMargin = Math.round(targetLeft + deltaLeft * fractionToEnd);
                        lp.width = Math.round(targetWidth + deltaWidth * fractionToEnd);
                        selectorView.requestLayout();
                    }
                });
                layoutAnimator.start();
            }
            return layoutAnimator;

        }
    }
}