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.annotation.NonNull;
20 import android.os.Parcel;
21 import android.text.Layout;
22 import android.text.ParcelableSpan;
23 import android.text.TextUtils;
24 
25 /**
26  * Span that allows defining the alignment of text at the paragraph level.
27  */
28 public interface AlignmentSpan extends ParagraphStyle {
29 
30     /**
31      * Returns the alignment of the text.
32      *
33      * @return the text alignment
34      */
getAlignment()35     Layout.Alignment getAlignment();
36 
37     /**
38      * Default implementation of the {@link AlignmentSpan}.
39      * <p>
40      * For example, a text written in a left to right language, like English, which is by default
41      * aligned to the left, can be aligned opposite to the layout direction like this:
42      * <pre>{@code SpannableString string = new SpannableString("Text with opposite alignment");
43      *string.setSpan(new AlignmentSpan.Standard(Layout.Alignment.ALIGN_OPPOSITE), 0,
44      *string.length(), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);}</pre>
45      * <img src="{@docRoot}reference/android/images/text/style/ltralignmentspan.png" />
46      * <figcaption>Align left to right text opposite to the layout direction.</figcaption>
47      * <p>
48      * A text written in a right to left language, like Hebrew, which is by default aligned to the
49      * right, can be aligned opposite to the layout direction like this:
50      * <pre>{@code SpannableString string = new SpannableString("טקסט עם יישור הפוך");
51      *string.setSpan(new AlignmentSpan.Standard(Layout.Alignment.ALIGN_OPPOSITE), 0,
52      *string.length(), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);}</pre>
53      * <img src="{@docRoot}reference/android/images/text/style/rtlalignmentspan.png" />
54      * <figcaption>Align right to left text opposite to the layout direction.</figcaption>
55      */
56     class Standard implements AlignmentSpan, ParcelableSpan {
57         private final Layout.Alignment mAlignment;
58 
59         /**
60          * Constructs a {@link Standard} from an alignment.
61          */
Standard(@onNull Layout.Alignment align)62         public Standard(@NonNull Layout.Alignment align) {
63             mAlignment = align;
64         }
65 
66         /**
67          * Constructs a {@link Standard} from a parcel.
68          */
Standard(@onNull Parcel src)69         public Standard(@NonNull Parcel src) {
70             mAlignment = Layout.Alignment.valueOf(src.readString());
71         }
72 
73         @Override
getSpanTypeId()74         public int getSpanTypeId() {
75             return getSpanTypeIdInternal();
76         }
77 
78         /** @hide */
79         @Override
getSpanTypeIdInternal()80         public int getSpanTypeIdInternal() {
81             return TextUtils.ALIGNMENT_SPAN;
82         }
83 
84         @Override
describeContents()85         public int describeContents() {
86             return 0;
87         }
88 
89         @Override
writeToParcel(@onNull Parcel dest, int flags)90         public void writeToParcel(@NonNull Parcel dest, int flags) {
91             writeToParcelInternal(dest, flags);
92         }
93 
94         /** @hide */
95         @Override
writeToParcelInternal(@onNull Parcel dest, int flags)96         public void writeToParcelInternal(@NonNull Parcel dest, int flags) {
97             dest.writeString(mAlignment.name());
98         }
99 
100         @Override
getAlignment()101         public Layout.Alignment getAlignment() {
102             return mAlignment;
103         }
104     }
105 }
106