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/*
* Copyright (C) 2006 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 android.text.style;
import android.text.TextPaint;
/**
* The classes that affect character-level text formatting extend this
* class. Most extend its subclass {@link MetricAffectingSpan}, but simple
* ones may just implement {@link UpdateAppearance}.
*/
public abstract class CharacterStyle {
public abstract void updateDrawState(TextPaint tp);
/**
* A given CharacterStyle can only applied to a single region of a given
* Spanned. If you need to attach the same CharacterStyle to multiple
* regions, you can use this method to wrap it with a new object that
* will have the same effect but be a distinct object so that it can
* also be attached without conflict.
*/
public static CharacterStyle wrap(CharacterStyle cs) {
if (cs instanceof MetricAffectingSpan) {
return new MetricAffectingSpan.Passthrough((MetricAffectingSpan) cs);
} else {
return new Passthrough(cs);
}
}
/**
* Returns "this" for most CharacterStyles, but for CharacterStyles
* that were generated by {@link #wrap}, returns the underlying
* CharacterStyle.
*/
public CharacterStyle getUnderlying() {
return this;
}
/**
* A Passthrough CharacterStyle is one that
* passes {@link #updateDrawState} calls through to the
* specified CharacterStyle while still being a distinct object,
* and is therefore able to be attached to the same Spannable
* to which the specified CharacterStyle is already attached.
*/
private static class Passthrough extends CharacterStyle {
private CharacterStyle mStyle;
/**
* Creates a new Passthrough of the specfied CharacterStyle.
*/
public Passthrough(CharacterStyle cs) {
mStyle = cs;
}
/**
* Passes updateDrawState through to the underlying CharacterStyle.
*/
@Override
public void updateDrawState(TextPaint tp) {
mStyle.updateDrawState(tp);
}
/**
* Returns the CharacterStyle underlying this one, or the one
* underlying it if it too is a Passthrough.
*/
@Override
public CharacterStyle getUnderlying() {
return mStyle.getUnderlying();
}
}
}
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