src/com/android/providers/media/photopicker/ui/PhotosTabFragment.java

/*
 * Copyright (C) 2021 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 com.android.providers.media.photopicker.ui;

import static com.android.providers.media.photopicker.ui.PhotosTabAdapter.COLUMN_COUNT;

import android.os.Bundle;
import android.text.TextUtils;
import android.view.View;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentManager;
import androidx.fragment.app.FragmentTransaction;
import androidx.recyclerview.widget.GridLayoutManager;

import com.android.providers.media.R;

import com.android.providers.media.photopicker.PhotoPickerActivity;
import com.android.providers.media.photopicker.data.model.Category;
import com.android.providers.media.photopicker.data.model.Category.CategoryType;
import com.android.providers.media.photopicker.data.model.Item;
import com.android.providers.media.photopicker.util.LayoutModeUtils;

import com.google.android.material.snackbar.Snackbar;

import java.text.NumberFormat;
import java.util.Locale;
import src.com.android.providers.media.util.StringUtils;

/**
 * Photos tab fragment for showing the photos
 */
public class PhotosTabFragment extends TabFragment {

    private static final int MINIMUM_SPAN_COUNT = 3;
    private static final String FRAGMENT_TAG = "PhotosTabFragment";
    private static final String EXTRA_CATEGORY_TYPE = "category_type";
    private static final String EXTRA_CATEGORY_NAME = "category_name";

    private boolean mIsDefaultCategory;
    @CategoryType
    private String mCategoryType;
    private String mCategoryName;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // After the configuration is changed, if the fragment is now shown, onViewCreated will not
        // be triggered. We need to restore the savedInstanceState in onCreate.
        // E.g. Click the albums -> preview one item -> rotate the device
        if (savedInstanceState != null) {
            mCategoryType = savedInstanceState.getString(EXTRA_CATEGORY_TYPE,
                    Category.CATEGORY_DEFAULT);
            mCategoryName = savedInstanceState.getString(EXTRA_CATEGORY_NAME,
                    /* defaultValue= */ "");
        }
    }

    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);

        final PhotosTabAdapter adapter = new PhotosTabAdapter(mSelection, mImageLoader,
                this::onItemClick, this::onItemLongClick);
        setEmptyMessage(R.string.picker_photos_empty_message);
        mIsDefaultCategory = TextUtils.equals(Category.CATEGORY_DEFAULT, mCategoryType);
        if (mIsDefaultCategory) {
            mPickerViewModel.getItems().observe(this, itemList -> {
                adapter.updateItemList(itemList);
                // Handle emptyView's visibility
                updateVisibilityForEmptyView(/* shouldShowEmptyView */ itemList.size() == 0);
            });
        } else {
            mPickerViewModel.getCategoryItems(mCategoryType).observe(this, itemList -> {
                // If the item count of the albums is zero, albums are not shown on the Albums tab.
                // The user can't launch the album items page when the album has zero items. So, we
                // don't need to show emptyView in the case.
                updateVisibilityForEmptyView(/* shouldShowEmptyView */ false);

                adapter.updateItemList(itemList);
            });
        }

        final GridLayoutManager layoutManager = new GridLayoutManager(getContext(), COLUMN_COUNT);
        final GridLayoutManager.SpanSizeLookup lookup = adapter.createSpanSizeLookup(layoutManager);
        layoutManager.setSpanSizeLookup(lookup);

        final PhotosTabItemDecoration itemDecoration = new PhotosTabItemDecoration(
                view.getContext());

        final int spacing = getResources().getDimensionPixelSize(R.dimen.picker_photo_item_spacing);
        final int photoSize = getResources().getDimensionPixelSize(R.dimen.picker_photo_size);
        mRecyclerView.setColumnWidth(photoSize + spacing);
        mRecyclerView.setMinimumSpanCount(MINIMUM_SPAN_COUNT);

        mRecyclerView.setLayoutManager(layoutManager);
        mRecyclerView.setAdapter(adapter);
        mRecyclerView.addItemDecoration(itemDecoration);
    }

    /**
     * Called when owning activity is saving state to be used to restore state during creation.
     *
     * @param state Bundle to save state
     */
    public void onSaveInstanceState(Bundle state) {
        super.onSaveInstanceState(state);
        state.putString(EXTRA_CATEGORY_TYPE, mCategoryType);
        state.putString(EXTRA_CATEGORY_NAME, mCategoryName);
    }

    @Override
    public void onResume() {
        super.onResume();

        if (mIsDefaultCategory) {
            ((PhotoPickerActivity) getActivity()).updateCommonLayouts(
                    LayoutModeUtils.MODE_PHOTOS_TAB, /* title */ "");
            hideProfileButton(/* hide */ false);
        } else {
            hideProfileButton(/* hide */ true);
            String categoryName = Category.getCategoryName(getContext(), mCategoryType);

            if (TextUtils.isEmpty(categoryName)) {
                categoryName = mCategoryName;
            }
            ((PhotoPickerActivity) getActivity()).updateCommonLayouts(
                    LayoutModeUtils.MODE_ALBUM_PHOTOS_TAB, categoryName);
        }
    }

    private void onItemClick(@NonNull View view) {
        if (mSelection.canSelectMultiple()) {
            final boolean isSelectedBefore = view.isSelected();

            if (isSelectedBefore) {
                mSelection.removeSelectedItem((Item) view.getTag());
            } else {
                if (!mSelection.isSelectionAllowed()) {
                    final int maxCount = mSelection.getMaxSelectionLimit();
                    final CharSequence quantityText =
                        StringUtils.getICUFormatString(
                            getResources(), maxCount, R.string.select_up_to);
                    final String itemCountString = NumberFormat.getInstance(Locale.getDefault())
                        .format(maxCount);
                    final CharSequence message = TextUtils.expandTemplate(quantityText,
                        itemCountString);
                    Snackbar.make(view, message, Snackbar.LENGTH_SHORT).show();
                    return;
                } else {
                    mSelection.addSelectedItem((Item) view.getTag());
                }
            }
            view.setSelected(!isSelectedBefore);
        } else {
            Item item = (Item) view.getTag();
            mSelection.setSelectedItem(item);
            ((PhotoPickerActivity) getActivity()).setResultAndFinishSelf();
        }
    }

    private boolean onItemLongClick(@NonNull View view) {
        Item item = (Item) view.getTag();
        if (!mSelection.canSelectMultiple()) {
            // In single select mode, if the item is previewed, we set it as selected item. This is
            // will assist in "Add" button click to return all selected items.
            // For multi select, long click only previews the item, and until user selects the item,
            // it doesn't get added to selected items. Also, there is no "Add" button in the preview
            // layout that can return selected items.
            mSelection.setSelectedItem(item);
        }
        mSelection.prepareItemForPreviewOnLongPress(item);
        // Transition to PreviewFragment.
        PreviewFragment.show(getActivity().getSupportFragmentManager(),
                PreviewFragment.getArgsForPreviewOnLongPress());
        return true;
    }

    /**
     * Create the fragment with the category and add it into the FragmentManager
     *
     * @param fm the fragment manager
     * @param category the category
     */
    public static void show(FragmentManager fm, Category category) {
        final FragmentTransaction ft = fm.beginTransaction();
        final PhotosTabFragment fragment = new PhotosTabFragment();
        fragment.mCategoryType = category.getCategoryType();
        fragment.mCategoryName = category.getCategoryName(/* context= */ null);
        ft.replace(R.id.fragment_container, fragment, FRAGMENT_TAG);
        if (!TextUtils.equals(category.getCategoryType(), Category.CATEGORY_DEFAULT)) {
            ft.addToBackStack(FRAGMENT_TAG);
        }
        ft.commitAllowingStateLoss();
    }

    /**
     * Get the fragment in the FragmentManager
     *
     * @param fm The fragment manager
     */
    public static Fragment get(FragmentManager fm) {
        return fm.findFragmentByTag(FRAGMENT_TAG);
    }
}