leanback/leanback/src/main/java/androidx/leanback/app/VerticalGridSupportFragment.java

/*
 * Copyright (C) 2014 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 androidx.leanback.app;

import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.leanback.R;
import androidx.leanback.transition.TransitionHelper;
import androidx.leanback.util.StateMachine.State;
import androidx.leanback.widget.BrowseFrameLayout;
import androidx.leanback.widget.ObjectAdapter;
import androidx.leanback.widget.OnChildLaidOutListener;
import androidx.leanback.widget.OnItemViewClickedListener;
import androidx.leanback.widget.OnItemViewSelectedListener;
import androidx.leanback.widget.Presenter;
import androidx.leanback.widget.Row;
import androidx.leanback.widget.RowPresenter;
import androidx.leanback.widget.VerticalGridPresenter;

/**
 * A fragment for creating leanback vertical grids.
 *
 * <p>Renders a vertical grid of objects given a {@link VerticalGridPresenter} and
 * an {@link ObjectAdapter}.
 */
public class VerticalGridSupportFragment extends BaseSupportFragment {
    static final String TAG = "VerticalGF";
    static final boolean DEBUG = false;

    private ObjectAdapter mAdapter;
    private VerticalGridPresenter mGridPresenter;
    VerticalGridPresenter.ViewHolder mGridViewHolder;
    OnItemViewSelectedListener mOnItemViewSelectedListener;
    private OnItemViewClickedListener mOnItemViewClickedListener;
    private Object mSceneAfterEntranceTransition;
    private int mSelectedPosition = -1;

    /**
     * State to setEntranceTransitionState(false)
     */
    final State STATE_SET_ENTRANCE_START_STATE = new State("SET_ENTRANCE_START_STATE") {
        @Override
        public void run() {
            setEntranceTransitionState(false);
        }
    };

    @Override
    void createStateMachineStates() {
        super.createStateMachineStates();
        mStateMachine.addState(STATE_SET_ENTRANCE_START_STATE);
    }

    @Override
    void createStateMachineTransitions() {
        super.createStateMachineTransitions();
        mStateMachine.addTransition(STATE_ENTRANCE_ON_PREPARED,
                STATE_SET_ENTRANCE_START_STATE, EVT_ON_CREATEVIEW);
    }

    /**
     * Sets the grid presenter.
     */
    public void setGridPresenter(@NonNull VerticalGridPresenter gridPresenter) {
        if (gridPresenter == null) {
            throw new IllegalArgumentException("Grid presenter may not be null");
        }
        mGridPresenter = gridPresenter;
        mGridPresenter.setOnItemViewSelectedListener(mViewSelectedListener);
        if (mOnItemViewClickedListener != null) {
            mGridPresenter.setOnItemViewClickedListener(mOnItemViewClickedListener);
        }
    }

    /**
     * Returns the grid presenter.
     */
    @Nullable
    public VerticalGridPresenter getGridPresenter() {
        return mGridPresenter;
    }

    /**
     * Sets the object adapter for the fragment.
     */
    public void setAdapter(@Nullable ObjectAdapter adapter) {
        mAdapter = adapter;
        updateAdapter();
    }

    /**
     * Returns the object adapter.
     */
    @Nullable
    public ObjectAdapter getAdapter() {
        return mAdapter;
    }

    final private OnItemViewSelectedListener mViewSelectedListener =
            new OnItemViewSelectedListener() {
        @Override
        public void onItemSelected(Presenter.ViewHolder itemViewHolder, Object item,
                RowPresenter.ViewHolder rowViewHolder, Row row) {
            int position = mGridViewHolder.getGridView().getSelectedPosition();
            if (DEBUG) Log.v(TAG, "grid selected position " + position);
            gridOnItemSelected(position);
            if (mOnItemViewSelectedListener != null) {
                mOnItemViewSelectedListener.onItemSelected(itemViewHolder, item,
                        rowViewHolder, row);
            }
        }
    };

    final private OnChildLaidOutListener mChildLaidOutListener =
            new OnChildLaidOutListener() {
        @Override
        public void onChildLaidOut(
                @NonNull ViewGroup parent,
                @NonNull View view,
                int position,
                long id
        ) {
            if (position == 0) {
                showOrHideTitle();
            }
        }
    };

    /**
     * Sets an item selection listener.
     */
    public void setOnItemViewSelectedListener(@Nullable OnItemViewSelectedListener listener) {
        mOnItemViewSelectedListener = listener;
    }

    void gridOnItemSelected(int position) {
        if (position != mSelectedPosition) {
            mSelectedPosition = position;
            showOrHideTitle();
        }
    }

    void showOrHideTitle() {
        if (mGridViewHolder.getGridView().findViewHolderForAdapterPosition(mSelectedPosition)
                == null) {
            return;
        }
        if (!mGridViewHolder.getGridView().hasPreviousViewInSameRow(mSelectedPosition)) {
            showTitle(true);
        } else {
            showTitle(false);
        }
    }

    /**
     * Sets an item clicked listener.
     */
    public void setOnItemViewClickedListener(@Nullable OnItemViewClickedListener listener) {
        mOnItemViewClickedListener = listener;
        if (mGridPresenter != null) {
            mGridPresenter.setOnItemViewClickedListener(mOnItemViewClickedListener);
        }
    }

    /**
     * Returns the item clicked listener.
     */
    @Nullable
    public OnItemViewClickedListener getOnItemViewClickedListener() {
        return mOnItemViewClickedListener;
    }

    @Override
    @Nullable
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container,
            @Nullable Bundle savedInstanceState) {
        ViewGroup root = (ViewGroup) inflater.inflate(R.layout.lb_vertical_grid_fragment,
                container, false);
        ViewGroup gridFrame = (ViewGroup) root.findViewById(R.id.grid_frame);
        installTitleView(inflater, gridFrame, savedInstanceState);
        getProgressBarManager().setRootView(root);

        ViewGroup gridDock = (ViewGroup) root.findViewById(R.id.browse_grid_dock);
        mGridViewHolder = mGridPresenter.onCreateViewHolder(gridDock);
        gridDock.addView(mGridViewHolder.view);
        mGridViewHolder.getGridView().setOnChildLaidOutListener(mChildLaidOutListener);

        mSceneAfterEntranceTransition = TransitionHelper.createScene(gridDock, new Runnable() {
            @Override
            public void run() {
                setEntranceTransitionState(true);
            }
        });

        updateAdapter();
        return root;
    }

    private void setupFocusSearchListener() {
        BrowseFrameLayout browseFrameLayout = (BrowseFrameLayout) getView().findViewById(
                R.id.grid_frame);
        browseFrameLayout.setOnFocusSearchListener(getTitleHelper().getOnFocusSearchListener());
    }

    @Override
    public void onStart() {
        super.onStart();
        setupFocusSearchListener();
    }

    @Override
    public void onDestroyView() {
        super.onDestroyView();
        mGridViewHolder.getGridView().swapAdapter(null, true);
        mGridViewHolder = null;
        mSceneAfterEntranceTransition = null;
    }

    /**
     * Sets the selected item position.
     */
    public void setSelectedPosition(int position) {
        mSelectedPosition = position;
        if(mGridViewHolder != null && mGridViewHolder.getGridView().getAdapter() != null) {
            mGridViewHolder.getGridView().setSelectedPositionSmooth(position);
        }
    }

    private void updateAdapter() {
        if (mGridViewHolder != null) {
            mGridPresenter.onBindViewHolder(mGridViewHolder, mAdapter);
            if (mSelectedPosition != -1) {
                mGridViewHolder.getGridView().setSelectedPosition(mSelectedPosition);
            }
        }
    }

    @Override
    @NonNull
    protected Object createEntranceTransition() {
        return TransitionHelper.loadTransition(getContext(),
                R.transition.lb_vertical_grid_entrance_transition);
    }

    @Override
    protected void runEntranceTransition(@Nullable Object entranceTransition) {
        TransitionHelper.runTransition(mSceneAfterEntranceTransition, entranceTransition);
    }

    void setEntranceTransitionState(boolean afterTransition) {
        mGridPresenter.setEntranceTransitionState(mGridViewHolder, afterTransition);
    }
}