core/java/com/android/internal/view/menu/MenuPopupHelper.java

/*
 * Copyright (C) 2010 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.internal.view.menu;

import android.content.Context;
import android.util.DisplayMetrics;
import android.view.KeyEvent;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.MeasureSpec;
import android.view.ViewGroup;
import android.view.ViewTreeObserver;
import android.widget.AdapterView;
import android.widget.BaseAdapter;
import android.widget.ListAdapter;
import android.widget.ListPopupWindow;
import android.widget.PopupWindow;

import java.util.ArrayList;

/**
 * Presents a menu as a small, simple popup anchored to another view.
 * @hide
 */
public class MenuPopupHelper implements AdapterView.OnItemClickListener, View.OnKeyListener,
        ViewTreeObserver.OnGlobalLayoutListener, PopupWindow.OnDismissListener,
        View.OnAttachStateChangeListener, MenuPresenter {
    private static final String TAG = "MenuPopupHelper";

    static final int ITEM_LAYOUT = com.android.internal.R.layout.popup_menu_item_layout;

    private Context mContext;
    private LayoutInflater mInflater;
    private ListPopupWindow mPopup;
    private MenuBuilder mMenu;
    private int mPopupMaxWidth;
    private View mAnchorView;
    private boolean mOverflowOnly;
    private ViewTreeObserver mTreeObserver;

    private MenuAdapter mAdapter;

    private Callback mPresenterCallback;

    public MenuPopupHelper(Context context, MenuBuilder menu) {
        this(context, menu, null, false);
    }

    public MenuPopupHelper(Context context, MenuBuilder menu, View anchorView) {
        this(context, menu, anchorView, false);
    }

    public MenuPopupHelper(Context context, MenuBuilder menu,
            View anchorView, boolean overflowOnly) {
        mContext = context;
        mInflater = LayoutInflater.from(context);
        mMenu = menu;
        mOverflowOnly = overflowOnly;

        final DisplayMetrics metrics = context.getResources().getDisplayMetrics();
        mPopupMaxWidth = metrics.widthPixels / 2;

        mAnchorView = anchorView;

        menu.addMenuPresenter(this);
    }

    public void setAnchorView(View anchor) {
        mAnchorView = anchor;
    }

    public void show() {
        if (!tryShow()) {
            throw new IllegalStateException("MenuPopupHelper cannot be used without an anchor");
        }
    }

    public boolean tryShow() {
        mPopup = new ListPopupWindow(mContext, null, com.android.internal.R.attr.popupMenuStyle);
        mPopup.setOnDismissListener(this);
        mPopup.setOnItemClickListener(this);

        mAdapter = new MenuAdapter(mMenu);
        mPopup.setAdapter(mAdapter);
        mPopup.setModal(true);

        View anchor = mAnchorView;
        if (anchor != null) {
            final boolean addGlobalListener = mTreeObserver == null;
            mTreeObserver = anchor.getViewTreeObserver(); // Refresh to latest
            if (addGlobalListener) mTreeObserver.addOnGlobalLayoutListener(this);
            anchor.addOnAttachStateChangeListener(this);
            mPopup.setAnchorView(anchor);
        } else {
            return false;
        }

        mPopup.setContentWidth(Math.min(measureContentWidth(mAdapter), mPopupMaxWidth));
        mPopup.setInputMethodMode(PopupWindow.INPUT_METHOD_NOT_NEEDED);
        mPopup.show();
        mPopup.getListView().setOnKeyListener(this);
        return true;
    }

    public void dismiss() {
        if (isShowing()) {
            mPopup.dismiss();
        }
    }

    public void onDismiss() {
        mPopup = null;
        if (mTreeObserver != null) {
            if (!mTreeObserver.isAlive()) mTreeObserver = mAnchorView.getViewTreeObserver();
            mTreeObserver.removeGlobalOnLayoutListener(this);
            mTreeObserver = null;
        }
        mAnchorView.removeOnAttachStateChangeListener(this);
    }

    public boolean isShowing() {
        return mPopup != null && mPopup.isShowing();
    }

    @Override
    public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
        MenuAdapter adapter = mAdapter;
        adapter.mAdapterMenu.performItemAction(adapter.getItem(position), 0);
    }

    public boolean onKey(View v, int keyCode, KeyEvent event) {
        if (event.getAction() == KeyEvent.ACTION_UP && keyCode == KeyEvent.KEYCODE_MENU) {
            dismiss();
            return true;
        }
        return false;
    }

    private int measureContentWidth(ListAdapter adapter) {
        // Menus don't tend to be long, so this is more sane than it looks.
        int width = 0;
        View itemView = null;
        int itemType = 0;
        final int widthMeasureSpec =
            MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);
        final int heightMeasureSpec =
            MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);
        final int count = adapter.getCount();
        for (int i = 0; i < count; i++) {
            final int positionType = adapter.getItemViewType(i);
            if (positionType != itemType) {
                itemType = positionType;
                itemView = null;
            }
            itemView = adapter.getView(i, itemView, null);
            itemView.measure(widthMeasureSpec, heightMeasureSpec);
            width = Math.max(width, itemView.getMeasuredWidth());
        }
        return width;
    }

    @Override
    public void onGlobalLayout() {
        if (isShowing()) {
            final View anchor = mAnchorView;
            if (anchor == null || !anchor.isShown()) {
                dismiss();
            } else if (isShowing()) {
                // Recompute window size and position
                mPopup.show();
            }
        }
    }

    @Override
    public void onViewAttachedToWindow(View v) {
    }

    @Override
    public void onViewDetachedFromWindow(View v) {
        if (mTreeObserver != null) {
            if (!mTreeObserver.isAlive()) mTreeObserver = v.getViewTreeObserver();
            mTreeObserver.removeGlobalOnLayoutListener(this);
        }
        v.removeOnAttachStateChangeListener(this);
    }

    @Override
    public void initForMenu(Context context, MenuBuilder menu) {
        // Don't need to do anything; we added as a presenter in the constructor.
    }

    @Override
    public MenuView getMenuView(ViewGroup root) {
        throw new UnsupportedOperationException("MenuPopupHelpers manage their own views");
    }

    @Override
    public void updateMenuView(boolean cleared) {
        if (mAdapter != null) mAdapter.notifyDataSetChanged();
    }

    @Override
    public void setCallback(Callback cb) {
        mPresenterCallback = cb;
    }

    @Override
    public boolean onSubMenuSelected(SubMenuBuilder subMenu) {
        if (subMenu.hasVisibleItems()) {
            MenuPopupHelper subPopup = new MenuPopupHelper(mContext, subMenu, mAnchorView, false);
            subPopup.setCallback(mPresenterCallback);
            if (subPopup.tryShow()) {
                if (mPresenterCallback != null) {
                    mPresenterCallback.onOpenSubMenu(subMenu);
                }
                return true;
            }
        }
        return false;
    }

    @Override
    public void onCloseMenu(MenuBuilder menu, boolean allMenusAreClosing) {
        // Only care about the (sub)menu we're presenting.
        if (menu != mMenu) return;

        dismiss();
        if (mPresenterCallback != null) {
            mPresenterCallback.onCloseMenu(menu, allMenusAreClosing);
        }
    }

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

    private class MenuAdapter extends BaseAdapter {
        private MenuBuilder mAdapterMenu;

        public MenuAdapter(MenuBuilder menu) {
            mAdapterMenu = menu;
        }

        public int getCount() {
            ArrayList<MenuItemImpl> items = mOverflowOnly ?
                    mAdapterMenu.getNonActionItems() : mAdapterMenu.getVisibleItems();
            return items.size();
        }

        public MenuItemImpl getItem(int position) {
            ArrayList<MenuItemImpl> items = mOverflowOnly ?
                    mAdapterMenu.getNonActionItems() : mAdapterMenu.getVisibleItems();
            return items.get(position);
        }

        public long getItemId(int position) {
            // Since a menu item's ID is optional, we'll use the position as an
            // ID for the item in the AdapterView
            return position;
        }

        public View getView(int position, View convertView, ViewGroup parent) {
            if (convertView == null) {
                convertView = mInflater.inflate(ITEM_LAYOUT, parent, false);
            }

            MenuView.ItemView itemView = (MenuView.ItemView) convertView;
            itemView.initialize(getItem(position), 0);
            return convertView;
        }
    }
}