Android example source code file (MetricAffectingSpan.java)

This example Android source code file (MetricAffectingSpan.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" ^TM.

Java - Android tags/keywords

android, characterstyle, drawing, graphics, metricaffectingspan, override, paint, passthrough, text, ui, updatelayout

The MetricAffectingSpan.java Android example source code

/*
 * 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.graphics.Paint;
import android.text.TextPaint;

/**
 * The classes that affect character-level text formatting in a way that
 * changes the width or height of characters extend this class.
 */
public abstract class MetricAffectingSpan
extends CharacterStyle
implements UpdateLayout {

	public abstract void updateMeasureState(TextPaint p);

    /**
     * Returns "this" for most MetricAffectingSpans, but for 
     * MetricAffectingSpans that were generated by {@link #wrap},
     * returns the underlying MetricAffectingSpan.
     */
    @Override
    public MetricAffectingSpan getUnderlying() {
        return this;
    }

    /**
     * A Passthrough MetricAffectingSpan is one that
     * passes {@link #updateDrawState} and {@link #updateMeasureState}
     * calls through to the specified MetricAffectingSpan 
     * while still being a distinct object,
     * and is therefore able to be attached to the same Spannable
     * to which the specified MetricAffectingSpan is already attached.
     */
    /* package */ static class Passthrough extends MetricAffectingSpan {
        private MetricAffectingSpan mStyle;
        
        /**
         * Creates a new Passthrough of the specfied MetricAffectingSpan.
         */
        public Passthrough(MetricAffectingSpan cs) {
            mStyle = cs;
        }

        /**
         * Passes updateDrawState through to the underlying MetricAffectingSpan.
         */
        @Override
        public void updateDrawState(TextPaint tp) {
            mStyle.updateDrawState(tp);
        }

        /**
         * Passes updateMeasureState through to the underlying MetricAffectingSpan.
         */
        @Override
        public void updateMeasureState(TextPaint tp) {
            mStyle.updateMeasureState(tp);
        }
    
        /**
         * Returns the MetricAffectingSpan underlying this one, or the one
         * underlying it if it too is a Passthrough.
         */
        @Override
        public MetricAffectingSpan getUnderlying() {
            return mStyle.getUnderlying();
        }
    }
}