/*
* Copyright (C) 2015 Matthew Lee
* Copyright (C) 2007 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 io.github.mthli.knife;
import android.graphics.Typeface;
import android.text.Html;
import android.text.Spanned;
import android.text.TextUtils;
import android.text.style.BulletSpan;
import android.text.style.CharacterStyle;
import android.text.style.ImageSpan;
import android.text.style.ParagraphStyle;
import android.text.style.QuoteSpan;
import android.text.style.StrikethroughSpan;
import android.text.style.StyleSpan;
import android.text.style.URLSpan;
import android.text.style.UnderlineSpan;
public class KnifeParser {
public static Spanned fromHtml(String source) {
return Html.fromHtml(source, null, new KnifeTagHandler());
}
public static String toHtml(Spanned text) {
StringBuilder out = new StringBuilder();
withinHtml(out, text);
return tidy(out.toString());
}
private static void withinHtml(StringBuilder out, Spanned text) {
int next;
for (int i = 0; i < text.length(); i = next) {
next = text.nextSpanTransition(i, text.length(), ParagraphStyle.class);
ParagraphStyle[] styles = text.getSpans(i, next, ParagraphStyle.class);
if (styles.length == 2) {
if (styles[0] instanceof BulletSpan && styles[1] instanceof QuoteSpan) {
// Let a <br> follow the BulletSpan or QuoteSpan end, so next++
withinBulletThenQuote(out, text, i, next++);
} else if (styles[0] instanceof QuoteSpan && styles[1] instanceof BulletSpan) {
withinQuoteThenBullet(out, text, i, next++);
} else {
withinContent(out, text, i, next);
}
} else if (styles.length == 1) {
if (styles[0] instanceof BulletSpan) {
withinBullet(out, text, i, next++);
} else if (styles[0] instanceof QuoteSpan) {
withinQuote(out, text, i, next++);
} else {
withinContent(out, text, i, next);
}
} else {
withinContent(out, text, i, next);
}
}
}
private static void withinBulletThenQuote(StringBuilder out, Spanned text, int start, int end) {
out.append("<ul><li>");
withinQuote(out, text, start, end);
out.append("</li></ul>");
}
private static void withinQuoteThenBullet(StringBuilder out, Spanned text, int start, int end) {
out.append("<blockquote>");
withinBullet(out, text, start, end);
out.append("</blockquote>");
}
private static void withinBullet(StringBuilder out, Spanned text, int start, int end) {
out.append("<ul>");
int next;
for (int i = start; i < end; i = next) {
next = text.nextSpanTransition(i, end, BulletSpan.class);
BulletSpan[] spans = text.getSpans(i, next, BulletSpan.class);
for (BulletSpan span : spans) {
out.append("<li>");
}
withinContent(out, text, i, next);
for (BulletSpan span : spans) {
out.append("</li>");
}
}
out.append("</ul>");
}
private static void withinQuote(StringBuilder out, Spanned text, int start, int end) {
int next;
for (int i = start; i < end; i = next) {
next = text.nextSpanTransition(i, end, QuoteSpan.class);
QuoteSpan[] quotes = text.getSpans(i, next, QuoteSpan.class);
for (QuoteSpan quote : quotes) {
out.append("<blockquote>");
}
withinContent(out, text, i, next);
for (QuoteSpan quote : quotes) {
out.append("</blockquote>");
}
}
}
private static void withinContent(StringBuilder out, Spanned text, int start, int end) {
int next;
for (int i = start; i < end; i = next) {
next = TextUtils.indexOf(text, '\n', i, end);
if (next < 0) {
next = end;
}
int nl = 0;
while (next < end && text.charAt(next) == '\n') {
next++;
nl++;
}
withinParagraph(out, text, i, next - nl, nl);
}
}
// Copy from https://android.googlesource.com/platform/frameworks/base/+/master/core/java/android/text/Html.java,
// remove some tag because we don't need them in Knife.
private static void withinParagraph(StringBuilder out, Spanned text, int start, int end, int nl) {
int next;
for (int i = start; i < end; i = next) {
next = text.nextSpanTransition(i, end, CharacterStyle.class);
CharacterStyle[] spans = text.getSpans(i, next, CharacterStyle.class);
for (int j = 0; j < spans.length; j++) {
if (spans[j] instanceof StyleSpan) {
int style = ((StyleSpan) spans[j]).getStyle();
if ((style & Typeface.BOLD) != 0) {
out.append("<b>");
}
if ((style & Typeface.ITALIC) != 0) {
out.append("<i>");
}
}
if (spans[j] instanceof UnderlineSpan) {
out.append("<u>");
}
// Use standard strikethrough tag <del> rather than <s> or <strike>
if (spans[j] instanceof StrikethroughSpan) {
out.append("<del>");
}
if (spans[j] instanceof URLSpan) {
out.append("<a href=\"");
out.append(((URLSpan) spans[j]).getURL());
out.append("\">");
}
if (spans[j] instanceof ImageSpan) {
out.append("<img src=\"");
out.append(((ImageSpan) spans[j]).getSource());
out.append("\">");
// Don't output the dummy character underlying the image.
i = next;
}
}
withinStyle(out, text, i, next);
for (int j = spans.length - 1; j >= 0; j--) {
if (spans[j] instanceof URLSpan) {
out.append("</a>");
}
if (spans[j] instanceof StrikethroughSpan) {
out.append("</del>");
}
if (spans[j] instanceof UnderlineSpan) {
out.append("</u>");
}
if (spans[j] instanceof StyleSpan) {
int style = ((StyleSpan) spans[j]).getStyle();
if ((style & Typeface.BOLD) != 0) {
out.append("</b>");
}
if ((style & Typeface.ITALIC) != 0) {
out.append("</i>");
}
}
}
}
for (int i = 0; i < nl; i++) {
out.append("<br>");
}
}
private static void withinStyle(StringBuilder out, CharSequence text, int start, int end) {
for (int i = start; i < end; i++) {
char c = text.charAt(i);
if (c == '<') {
out.append("<");
} else if (c == '>') {
out.append(">");
} else if (c == '&') {
out.append("&");
} else if (c >= 0xD800 && c <= 0xDFFF) {
if (c < 0xDC00 && i + 1 < end) {
char d = text.charAt(i + 1);
if (d >= 0xDC00 && d <= 0xDFFF) {
i++;
int codepoint = 0x010000 | (int) c - 0xD800 << 10 | (int) d - 0xDC00;
out.append("&#").append(codepoint).append(";");
}
}
} else if (c > 0x7E || c < ' ') {
out.append("&#").append((int) c).append(";");
} else if (c == ' ') {
while (i + 1 < end && text.charAt(i + 1) == ' ') {
out.append(" ");
i++;
}
out.append(' ');
} else {
out.append(c);
}
}
}
private static String tidy(String html) {
return html.replaceAll("</ul>(<br>)?", "</ul>").replaceAll("</blockquote>(<br>)?", "</blockquote>");
}
}
