content: /*
   * 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();
          }
      }
  }
  