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 
17 package android.text.style;
18 
19 import android.text.TextPaint;
20 
21 /**
22  * The classes that affect character-level text formatting in a way that
23  * changes the width or height of characters extend this class.
24  */
25 public abstract class MetricAffectingSpan
26 extends CharacterStyle
27 implements UpdateLayout {
28 
updateMeasureState(TextPaint p)29     public abstract void updateMeasureState(TextPaint p);
30 
31     /**
32      * Returns "this" for most MetricAffectingSpans, but for
33      * MetricAffectingSpans that were generated by {@link #wrap},
34      * returns the underlying MetricAffectingSpan.
35      */
36     @Override
getUnderlying()37     public MetricAffectingSpan getUnderlying() {
38         return this;
39     }
40 
41     /**
42      * A Passthrough MetricAffectingSpan is one that
43      * passes {@link #updateDrawState} and {@link #updateMeasureState}
44      * calls through to the specified MetricAffectingSpan
45      * while still being a distinct object,
46      * and is therefore able to be attached to the same Spannable
47      * to which the specified MetricAffectingSpan is already attached.
48      */
49     /* package */ static class Passthrough extends MetricAffectingSpan {
50         private MetricAffectingSpan mStyle;
51 
52         /**
53          * Creates a new Passthrough of the specfied MetricAffectingSpan.
54          */
Passthrough(MetricAffectingSpan cs)55         public Passthrough(MetricAffectingSpan cs) {
56             mStyle = cs;
57         }
58 
59         /**
60          * Passes updateDrawState through to the underlying MetricAffectingSpan.
61          */
62         @Override
updateDrawState(TextPaint tp)63         public void updateDrawState(TextPaint tp) {
64             mStyle.updateDrawState(tp);
65         }
66 
67         /**
68          * Passes updateMeasureState through to the underlying MetricAffectingSpan.
69          */
70         @Override
updateMeasureState(TextPaint tp)71         public void updateMeasureState(TextPaint tp) {
72             mStyle.updateMeasureState(tp);
73         }
74 
75         /**
76          * Returns the MetricAffectingSpan underlying this one, or the one
77          * underlying it if it too is a Passthrough.
78          */
79         @Override
getUnderlying()80         public MetricAffectingSpan getUnderlying() {
81             return mStyle.getUnderlying();
82         }
83     }
84 }
85