1/*
2 * Copyright (C) 2006 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package android.text.style;
18
19import android.graphics.Canvas;
20import android.graphics.Paint;
21import android.graphics.Rect;
22import android.graphics.drawable.Drawable;
23
24import java.lang.ref.WeakReference;
25
26/**
27 *
28 */
29public abstract class DynamicDrawableSpan extends ReplacementSpan {
30    private static final String TAG = "DynamicDrawableSpan";
31
32    /**
33     * A constant indicating that the bottom of this span should be aligned
34     * with the bottom of the surrounding text, i.e., at the same level as the
35     * lowest descender in the text.
36     */
37    public static final int ALIGN_BOTTOM = 0;
38
39    /**
40     * A constant indicating that the bottom of this span should be aligned
41     * with the baseline of the surrounding text.
42     */
43    public static final int ALIGN_BASELINE = 1;
44
45    protected final int mVerticalAlignment;
46
47    public DynamicDrawableSpan() {
48        mVerticalAlignment = ALIGN_BOTTOM;
49    }
50
51    /**
52     * @param verticalAlignment one of {@link #ALIGN_BOTTOM} or {@link #ALIGN_BASELINE}.
53     */
54    protected DynamicDrawableSpan(int verticalAlignment) {
55        mVerticalAlignment = verticalAlignment;
56    }
57
58    /**
59     * Returns the vertical alignment of this span, one of {@link #ALIGN_BOTTOM} or
60     * {@link #ALIGN_BASELINE}.
61     */
62    public int getVerticalAlignment() {
63        return mVerticalAlignment;
64    }
65
66    /**
67     * Your subclass must implement this method to provide the bitmap
68     * to be drawn.  The dimensions of the bitmap must be the same
69     * from each call to the next.
70     */
71    public abstract Drawable getDrawable();
72
73    @Override
74    public int getSize(Paint paint, CharSequence text,
75                         int start, int end,
76                         Paint.FontMetricsInt fm) {
77        Drawable d = getCachedDrawable();
78        Rect rect = d.getBounds();
79
80        if (fm != null) {
81            fm.ascent = -rect.bottom;
82            fm.descent = 0;
83
84            fm.top = fm.ascent;
85            fm.bottom = 0;
86        }
87
88        return rect.right;
89    }
90
91    @Override
92    public void draw(Canvas canvas, CharSequence text,
93                     int start, int end, float x,
94                     int top, int y, int bottom, Paint paint) {
95        Drawable b = getCachedDrawable();
96        canvas.save();
97
98        int transY = bottom - b.getBounds().bottom;
99        if (mVerticalAlignment == ALIGN_BASELINE) {
100            transY -= paint.getFontMetricsInt().descent;
101        }
102
103        canvas.translate(x, transY);
104        b.draw(canvas);
105        canvas.restore();
106    }
107
108    private Drawable getCachedDrawable() {
109        WeakReference<Drawable> wr = mDrawableRef;
110        Drawable d = null;
111
112        if (wr != null)
113            d = wr.get();
114
115        if (d == null) {
116            d = getDrawable();
117            mDrawableRef = new WeakReference<Drawable>(d);
118        }
119
120        return d;
121    }
122
123    private WeakReference<Drawable> mDrawableRef;
124}
125
126