DiffText.java

/*
 * Copyright (c) 2011, 2012 Roberto Tyley
 *
 * This file is part of 'Agit' - an Android Git client.
 *
 * Agit is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Agit is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see http://www.gnu.org/licenses/ .
 */

package com.madgag.agit.diff;

import static android.text.Spanned.SPAN_EXCLUSIVE_EXCLUSIVE;
import static com.google.common.collect.Lists.newArrayList;
import static name.fraser.neil.plaintext.diff_match_patch.Operation.INSERT;
import android.text.Editable;
import android.text.style.CharacterStyle;

import java.util.LinkedList;
import java.util.List;

import name.fraser.neil.plaintext.diff_match_patch.Diff;
import name.fraser.neil.plaintext.diff_match_patch.Operation;

public class DiffText {

    private List<CharacterStyle> insertSpans, deleteSpans;

    private final Editable spannableText;

    public DiffText(Editable spannableText) {
        this.spannableText = spannableText;
    }

    public void setTransitionProgress(float proportion) {
        updateDisplayWith(proportion);
    }

    void updateDisplayWith(float proportion) {
        DeltaSpan insertSpan = new DeltaSpan(true, proportion);
        DeltaSpan deleteSpan = new DeltaSpan(false, proportion);
        replace(insertSpans, insertSpan);
        replace(deleteSpans, deleteSpan);
    }

    private void replace(List<CharacterStyle> deltaSpans, CharacterStyle spanStyle) {
        for (int i = 0; i < deltaSpans.size(); ++i) {
            CharacterStyle oldSpanStyle = deltaSpans.get(i);
            int start = spannableText.getSpanStart(oldSpanStyle), end = spannableText.getSpanEnd(oldSpanStyle);
            spannableText.removeSpan(oldSpanStyle);
            CharacterStyle mySpanStyle = CharacterStyle.wrap(spanStyle);
            spannableText.setSpan(mySpanStyle, start, end, SPAN_EXCLUSIVE_EXCLUSIVE);
            deltaSpans.set(i, mySpanStyle);
        }
    }

    public void initWith(LinkedList<Diff> diffs, float state) {
        DeltaSpan insertSpan = new DeltaSpan(true, state);
        DeltaSpan deleteSpan = new DeltaSpan(false, state);
        insertSpans = newArrayList();
        deleteSpans = newArrayList();
        spannableText.clear();
        for (Diff diff : diffs) {
            spannableText.append(diff.text);
            if (diff.operation != Operation.EQUAL) {
                boolean insertNotDelete = diff.operation == INSERT;
                CharacterStyle deltaSpan = CharacterStyle.wrap(insertNotDelete ? insertSpan : deleteSpan);
                spannableText.setSpan(deltaSpan, spannableText.length() - diff.text.length(), spannableText.length(),
                        SPAN_EXCLUSIVE_EXCLUSIVE);
                (insertNotDelete ? insertSpans : deleteSpans).add(deltaSpan);
            }
        }
    }
}