Android example source code file (ReplacementTransformationMethod.java)

This example Android source code file (ReplacementTransformationMethod.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, charsequence, class, drawing, editable, getchars, paint, rect, replacementcharsequence, replacementtransformationmethod, spannable, spanned, spannedreplacementcharsequence, spannedstring, string, text, ui, view

The ReplacementTransformationMethod.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.method;

import android.graphics.Rect;
import android.text.Editable;
import android.text.GetChars;
import android.text.Spannable;
import android.text.Spanned;
import android.text.SpannedString;
import android.text.TextUtils;
import android.view.View; 

/**
 * This transformation method causes the characters in the {@link #getOriginal}
 * array to be replaced by the corresponding characters in the
 * {@link #getReplacement} array.
 */
public abstract class ReplacementTransformationMethod
implements TransformationMethod
{
    /**
     * Returns the list of characters that are to be replaced by other
     * characters when displayed.
     */
    protected abstract char[] getOriginal();
    /**
     * Returns a parallel array of replacement characters for the ones
     * that are to be replaced.
     */
    protected abstract char[] getReplacement();

    /**
     * Returns a CharSequence that will mirror the contents of the
     * source CharSequence but with the characters in {@link #getOriginal}
     * replaced by ones from {@link #getReplacement}.
     */
    public CharSequence getTransformation(CharSequence source, View v) {
        char[] original = getOriginal();
        char[] replacement = getReplacement();

        /*
         * Short circuit for faster display if the text will never change.
         */
        if (!(source instanceof Editable)) {
            /*
             * Check whether the text does not contain any of the
             * source characters so can be used unchanged.
             */
            boolean doNothing = true;
            int n = original.length;
            for (int i = 0; i < n; i++) {
                if (TextUtils.indexOf(source, original[i]) >= 0) {
                    doNothing = false;
                    break;
                }
            }
            if (doNothing) {
                return source;
            }

            if (!(source instanceof Spannable)) {
                /*
                 * The text contains some of the source characters,
                 * but they can be flattened out now instead of
                 * at display time.
                 */
                if (source instanceof Spanned) {
                    return new SpannedString(new SpannedReplacementCharSequence(
                                                        (Spanned) source,
                                                        original, replacement));
                } else {
                    return new ReplacementCharSequence(source,
                                                       original,
                                                       replacement).toString();
                }
            }
        }

        if (source instanceof Spanned) {
            return new SpannedReplacementCharSequence((Spanned) source,
                                                      original, replacement);
        } else {
            return new ReplacementCharSequence(source, original, replacement);
        }
    }

    public void onFocusChanged(View view, CharSequence sourceText,
                               boolean focused, int direction,
                               Rect previouslyFocusedRect) {
        // This callback isn't used.
    }

    private static class ReplacementCharSequence
    implements CharSequence, GetChars {
        private char[] mOriginal, mReplacement;

        public ReplacementCharSequence(CharSequence source, char[] original,
                                       char[] replacement) {
            mSource = source;
            mOriginal = original;
            mReplacement = replacement;
        }

        public int length() {
            return mSource.length();
        }

        public char charAt(int i) {
            char c = mSource.charAt(i);

            int n = mOriginal.length;
            for (int j = 0; j < n; j++) {
                if (c == mOriginal[j]) {
                    c = mReplacement[j];
                }
            }

            return c;
        }

        public CharSequence subSequence(int start, int end) {
            char[] c = new char[end - start];

            getChars(start, end, c, 0);
            return new String(c);
        }

        public String toString() {
            char[] c = new char[length()];

            getChars(0, length(), c, 0);
            return new String(c);
        }

        public void getChars(int start, int end, char[] dest, int off) {
            TextUtils.getChars(mSource, start, end, dest, off);
            int offend = end - start + off;
            int n = mOriginal.length;

            for (int i = off; i < offend; i++) {
                char c = dest[i];

                for (int j = 0; j < n; j++) {
                    if (c == mOriginal[j]) {
                        dest[i] = mReplacement[j];
                    }
                }
            }
        }

        private CharSequence mSource;
    }

    private static class SpannedReplacementCharSequence
    extends ReplacementCharSequence
    implements Spanned
    {
        public SpannedReplacementCharSequence(Spanned source, char[] original,
                                              char[] replacement) {
            super(source, original, replacement);
            mSpanned = source;
        }

        public CharSequence subSequence(int start, int end) {
            return new SpannedString(this).subSequence(start, end);
        }

        public <T> T[] getSpans(int start, int end, Class type) {
            return mSpanned.getSpans(start, end, type);
        }

        public int getSpanStart(Object tag) {
            return mSpanned.getSpanStart(tag);
        }

        public int getSpanEnd(Object tag) {
            return mSpanned.getSpanEnd(tag);
        }

        public int getSpanFlags(Object tag) {
            return mSpanned.getSpanFlags(tag);
        }

        public int nextSpanTransition(int start, int end, Class type) {
            return mSpanned.nextSpanTransition(start, end, type);
        }

        private Spanned mSpanned;
    }
}