ConversationOverlayItem.java revision 31c38a8247b4583ac1cc506acf8454d8922ee491 
1/*
2 * Copyright (C) 2012 Google Inc.
3 * Licensed to The Android Open Source Project.
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
8 *
9 *      http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18package com.android.mail.browse;
19
20import android.content.Context;
21import android.view.LayoutInflater;
22import android.view.View;
23import android.view.ViewGroup;
24import android.widget.Adapter;
25import android.widget.CursorAdapter;
26
27import com.android.mail.ui.ConversationViewFragment;
28import com.android.mail.utils.LogUtils;
29
30public abstract class ConversationOverlayItem {
31    private int mHeight;  // in px
32    private int mTop;  // in px
33    private boolean mNeedsMeasure;
34
35    public static final String LOG_TAG = ConversationViewFragment.LAYOUT_TAG;
36
37    /**
38     * @see Adapter#getItemViewType(int)
39     */
40    public abstract int getType();
41    /**
42     * Inflate and perform one-time initialization on a view for later binding.
43     */
44    public abstract View createView(Context context, LayoutInflater inflater,
45            ViewGroup parent);
46
47    /**
48     * @see CursorAdapter#bindView(View, Context, android.database.Cursor)
49     * @param v a view to bind to
50     * @param measureOnly true iff we are binding this view only to measure its height (so items
51     * know they can cut certain corners that do not affect a view's height)
52     */
53    public abstract void bindView(View v, boolean measureOnly);
54    /**
55     * Returns true if this overlay view is meant to be positioned right on top of the overlay
56     * below. This special positioning allows {@link ConversationContainer} to stack overlays
57     * together even when zoomed into a conversation, when the overlay spacers spread farther
58     * apart.
59     */
60    public abstract boolean isContiguous();
61
62    /**
63     * This method's behavior is critical and requires some 'splainin.
64     * <p>
65     * Subclasses that return a zero-size height to the {@link ConversationContainer} will
66     * cause the scrolling/recycling logic there to remove any matching view from the container.
67     * The item should switch to returning a non-zero height when its view should re-appear.
68     * <p>
69     * It's imperative that this method stay in sync with the current height of the HTML spacer
70     * that matches this overlay.
71     */
72    public int getHeight() {
73        return mHeight;
74    }
75
76    public void setHeight(int h) {
77        LogUtils.i(LOG_TAG, "IN setHeight=%dpx of overlay item: %s", h, this);
78        if (mHeight != h) {
79            mHeight = h;
80            mNeedsMeasure = true;
81        }
82    }
83
84    public int getTop() {
85        return mTop;
86    }
87
88    public void setTop(int top) {
89        mTop = top;
90    }
91
92    public boolean isMeasurementValid() {
93        return !mNeedsMeasure;
94    }
95
96    public void markMeasurementValid() {
97        mNeedsMeasure = false;
98    }
99
100    public void invalidateMeasurement() {
101        mNeedsMeasure = true;
102    }
103
104    public boolean canBecomeSnapHeader() {
105        return false;
106    }
107
108    public boolean canPushSnapHeader() {
109        return false;
110    }
111
112}
113