src/com/android/documentsui/dirlist/DocumentHolder.java

/*
 * Copyright (C) 2015 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.documentsui.dirlist;

import android.annotation.ColorInt;
import android.content.Context;
import android.database.Cursor;
import android.graphics.Rect;
import android.os.Build;
import android.support.v7.widget.RecyclerView;
import android.text.TextUtils;
import android.view.KeyEvent;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewPropertyAnimator;
import android.widget.FrameLayout;
import android.widget.ImageView;

import com.android.documentsui.R;
import com.android.documentsui.base.DebugFlags;
import com.android.documentsui.base.DocumentInfo;
import com.android.documentsui.base.Events.InputEvent;
import com.android.documentsui.base.Shared;
import com.android.documentsui.ui.DocumentDebugInfo;

import javax.annotation.Nullable;

public abstract class DocumentHolder
        extends RecyclerView.ViewHolder
        implements View.OnKeyListener, DocumentDetails {

    static final float DISABLED_ALPHA = 0.3f;

    protected final Context mContext;
    protected final @ColorInt int mDefaultBgColor;
    protected final @ColorInt int mSelectedBgColor;
    protected final @ColorInt int mDroppableBgColor;
    protected final @ColorInt int mNotDroppableBgColor;

    protected @Nullable String mModelId;

    private final View mSelectionHotspot;
    private final @Nullable FrameLayout mDebugContainer;
    private @Nullable DocumentDebugInfo mDebugInfo;

    // See #addKeyEventListener for details on the need for this field.
    private KeyboardEventListener mKeyEventListener;

    public DocumentHolder(Context context, ViewGroup parent, int layout) {
        this(context, inflateLayout(context, parent, layout));
    }

    public DocumentHolder(Context context, View item) {
        super(item);

        itemView.setOnKeyListener(this);

        mContext = context;

        mDefaultBgColor = context.getColor(R.color.item_doc_background);
        mSelectedBgColor = context.getColor(R.color.item_doc_background_selected);
        mDroppableBgColor = context.getColor(R.color.item_doc_droppable_background);
        mNotDroppableBgColor = context.getColor(R.color.item_doc_not_droppable_background);

        mSelectionHotspot = itemView.findViewById(R.id.icon_check);

        mDebugContainer = (FrameLayout) itemView.findViewById(R.id.debug_info);
    }

    /**
     * Binds the view to the given item data.
     * @param cursor
     * @param modelId
     * @param state
     */
    public abstract void bind(Cursor cursor, String modelId);

    @Override
    public boolean hasModelId() {
        return !TextUtils.isEmpty(mModelId);
    }

    @Override
    public String getModelId() {
        return mModelId;
    }

    /**
     * Makes the associated item view appear selected. Note that this merely affects the appearance
     * of the view, it doesn't actually select the item.
     * TODO: Use the DirectoryItemAnimator instead of manually controlling animation using a boolean
     * flag.
     *
     * @param selected
     * @param animate Whether or not to animate the change. Only selection changes initiated by the
     *            selection manager should be animated. See
     *            {@link ModelBackedDocumentsAdapter#onBindViewHolder(DocumentHolder, int, java.util.List)}
     */
    public void setSelected(boolean selected, boolean animate) {
        // Note: the animate param doesn't apply for this base implementation, because the
        // DirectoryItemAnimator takes care of it. It's required by subclasses, which perform their
        // own animation.
        itemView.setActivated(selected);
        itemView.setBackgroundColor(selected ? mSelectedBgColor : mDefaultBgColor);
    }

    /**
     * Highlights the associated item view to indicate it's droppable.
     */
    public void setDroppableHighlight(boolean droppable) {
        // If item is already selected, its highlight should not be changed.
        if (itemView.isActivated()) {
            return;
        }

        itemView.setBackgroundColor(droppable ? mDroppableBgColor : mNotDroppableBgColor);
    }

    /**
     * Reset the associated item view's droppable background highlight.
     */
    public void resetDropHighlight() {
        if (itemView.isActivated()) {
            return;
        }

        itemView.setBackgroundColor(mDefaultBgColor);
    }

    public void setEnabled(boolean enabled) {
        setEnabledRecursive(itemView, enabled);
    }

    @Override
    public boolean onKey(View v, int keyCode, KeyEvent event) {
        assert(mKeyEventListener != null);
        return mKeyEventListener.onKey(this,  keyCode,  event);
    }

    /**
     * Installs a delegate to receive keyboard input events. This arrangement is necessitated
     * by the fact that a single listener cannot listen to all keyboard events
     * on RecyclerView (our parent view). Not sure why this is, but have been
     * assured it is the case.
     *
     * <p>Ideally we'd not involve DocumentHolder in propagation of events like this.
     */
    public void addKeyEventListener(KeyboardEventListener listener) {
        assert(mKeyEventListener == null);
        mKeyEventListener = listener;
    }

    @Override
    public boolean isInSelectionHotspot(InputEvent event) {
        // Do everything in global coordinates - it makes things simpler.
        int[] coords = new int[2];
        mSelectionHotspot.getLocationOnScreen(coords);
        Rect rect = new Rect(coords[0], coords[1], coords[0] + mSelectionHotspot.getWidth(),
                coords[1] + mSelectionHotspot.getHeight());

        // If the tap occurred within the icon rect, consider it a selection.
        return rect.contains((int) event.getRawX(), (int) event.getRawY());
    }

    @Override
    public boolean isInDragHotspot(InputEvent event) {
        return false;
    }

    protected void includeDebugInfo(DocumentInfo doc) {
        if (mDebugContainer == null) {
            return;
        }
        if (DebugFlags.getDocumentDetailsEnabled()) {
            assert(Build.IS_DEBUGGABLE);
            if (mDebugInfo == null) {
                assert(mDebugContainer.getChildAt(0) == null);
                mDebugInfo = inflateLayout(mContext, mDebugContainer, R.layout.document_debug_info);
                mDebugContainer.addView(mDebugInfo);
            }
            mDebugInfo.update(doc);
            mDebugContainer.setVisibility(View.VISIBLE);
        } else {
            mDebugContainer.setVisibility(View.GONE);
        }
    }

    static void setEnabledRecursive(View itemView, boolean enabled) {
        if (itemView == null || itemView.isEnabled() == enabled) {
            return;
        }
        itemView.setEnabled(enabled);

        if (itemView instanceof ViewGroup) {
            final ViewGroup vg = (ViewGroup) itemView;
            for (int i = vg.getChildCount() - 1; i >= 0; i--) {
                setEnabledRecursive(vg.getChildAt(i), enabled);
            }
        }
    }

    private static <V extends View> V inflateLayout(Context context, ViewGroup parent, int layout) {
        final LayoutInflater inflater = LayoutInflater.from(context);
        return (V) inflater.inflate(layout, parent, false);
    }

    static ViewPropertyAnimator fade(ImageView view, float alpha) {
        return view.animate().setDuration(Shared.CHECK_ANIMATION_DURATION).alpha(alpha);
    }

    /**
     * Implement this in order to be able to respond to events coming from DocumentHolders.
     * TODO: Make this bubble up logic events rather than having imperative commands.
     */
    interface KeyboardEventListener {

        /**
         * Handles key events on the document holder.
         *
         * @param doc The target DocumentHolder.
         * @param keyCode Key code for the event.
         * @param event KeyEvent for the event.
         * @return Whether the event was handled.
         */
        public boolean onKey(DocumentHolder doc, int keyCode, KeyEvent event);
    }
}