Html.java

/*
 * 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 com.wisedu.scc.love.widget.html;

import android.content.Context;
import android.content.res.ColorStateList;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Typeface;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.text.Editable;
import android.text.Spannable;
import android.text.SpannableStringBuilder;
import android.text.Spanned;
import android.text.TextUtils;
import android.text.style.ForegroundColorSpan;
import android.text.style.ImageSpan;
import android.text.style.ParagraphStyle;
import android.text.style.QuoteSpan;
import android.text.style.RelativeSizeSpan;
import android.text.style.StyleSpan;
import android.text.style.SubscriptSpan;
import android.text.style.SuperscriptSpan;
import android.text.style.TextAppearanceSpan;
import android.text.style.TypefaceSpan;
import android.text.style.UnderlineSpan;

import com.wisedu.scc.love.R;
import com.wisedu.scc.love.widget.emoji.EmojiConversionUtil;
import com.wisedu.scc.love.widget.html.span.AdvancedUrlSpan;

import org.xml.sax.Attributes;
import org.xml.sax.ContentHandler;
import org.xml.sax.InputSource;
import org.xml.sax.Locator;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;

import java.io.IOException;
import java.io.StringReader;
import java.net.URL;
import java.util.HashMap;

/**
 * This class processes HTML strings into displayable styled text. Not all HTML
 * tags are supported.
 */
public class Html {
	/**
	 * Retrieves images for HTML <img> tags.
	 */
	public static interface ImageGetter {
		/**
		 * This methos is called when the HTML parser encounters an <img>
		 * tag. The <code>source</code> argument is the string from the "src"
		 * attribute; the return value should be a Drawable representation of
		 * the image or <code>null</code> for a generic replacement image. Make
		 * sure you call setBounds() on your Drawable if it doesn't already have
		 * its bounds set.
		 */
		public Drawable getDrawable(String source);
	}

	/**
	 * Is notified when HTML tags are encountered that the parser does not know
	 * how to interpret.
	 */
	public static interface TagHandler {
		/**
		 * This method will be called whenn the HTML parser encounters a tag
		 * that it does not know how to interpret.
		 */
		public void handleTag(boolean opening, String tag, Editable output,
                              XMLReader xmlReader);
	}
	
	private static int size;
	
	private static Context context;
	
	private static ImageGetter defImageGetter  = new ImageGetter() {
		
		@Override
		public Drawable getDrawable(String source) {
			Bitmap bitmap = loadBitmap(source);

			if (bitmap != null) {
				Drawable drawable = new BitmapDrawable(bitmap);
				return drawable;
			}
			return null;
		}
		
		/**
		 * Loads a Bitmap from the given url.
		 * 
		 * @param url
		 * @return a Bitmap, or null if it could not be loaded.
		 */
		protected Bitmap loadBitmap(String url) {
			try {
				return BitmapFactory.decodeStream(new URL(url).openStream());
			} catch (IOException io) {
				return null;
			}
		}
	};
	
	public static Context getContext() {
		return context;
	}

	public static void setContext(Context context) {
		Html.context = context;
	}

	public static int getEmSize() {
		return size;
	}

	public static void setEmSize(int size) {
		// 用EditText的size会使得表情添加上去略小，这边hack一下
		Html.size = size + 10;
	}

	private Html() {
	}

	/**
	 * Returns displayable styled text from the provided HTML string. Any
	 * <img> tags in the HTML will display as a generic replacement image
	 * which your program can then go through and replace with real images.
	 *
	 * <p>
	 * This uses TagSoup to handle real HTML, including all of the brokenness
	 * found in the wild.
	 */
	public static Spanned fromHtml(String source) {
		return fromHtml(source, defImageGetter, null);
	}

	/**
	 * Lazy initialization holder for HTML parser. This class will a) be
	 * preloaded by the zygote, or b) not loaded until absolutely necessary.
	 */
	private static class HtmlParser {
		private static final HTMLSchema schema = new HTMLSchema();
	}

	/**
	 * Returns displayable styled text from the provided HTML string. Any
	 * <img> tags in the HTML will use the specified ImageGetter to
	 * request a representation of the image (use null if you don't want this)
	 * and the specified TagHandler to handle unknown tags (specify null if you
	 * don't want this).
	 *
	 * <p>
	 * This uses TagSoup to handle real HTML, including all of the brokenness
	 * found in the wild.
	 */
	public static Spanned fromHtml(String source, ImageGetter imageGetter,
			TagHandler tagHandler) {
		Parser parser = new Parser();
		try {
			parser.setProperty(Parser.schemaProperty, HtmlParser.schema);
		} catch (org.xml.sax.SAXNotRecognizedException e) {
			// Should not happen.
			throw new RuntimeException(e);
		} catch (org.xml.sax.SAXNotSupportedException e) {
			// Should not happen.
			throw new RuntimeException(e);
		}

		HtmlToSpannedConverter converter = new HtmlToSpannedConverter(source,
				imageGetter, tagHandler, parser);
		return converter.convert();
	}
}

class HtmlToSpannedConverter implements ContentHandler {

	private static final float[] HEADER_SIZES = { 1.5f, 1.4f, 1.3f, 1.2f, 1.1f,
			1f, };

	private String mSource;
	private XMLReader mReader;
	private SpannableStringBuilder mSpannableStringBuilder;
	private Html.ImageGetter mImageGetter;
	private Html.TagHandler mTagHandler;

	public HtmlToSpannedConverter(String source, Html.ImageGetter imageGetter,
			Html.TagHandler tagHandler, Parser parser) {
		mSource = source;
		mSpannableStringBuilder = new SpannableStringBuilder();
		mImageGetter = imageGetter;
		mTagHandler = tagHandler;
		mReader = parser;
	}

	public Spanned convert() {
		mReader.setContentHandler(this);
		try {
			mReader.parse(new InputSource(new StringReader(mSource)));
		} catch (IOException e) {
			// We are reading from a string. There should not be IO problems.
			throw new RuntimeException(e);
		} catch (SAXException e) {
			// TagSoup doesn't throw parse exceptions.
			throw new RuntimeException(e);
		}

		// Fix flags and range for paragraph-type markup.
		Object[] obj = mSpannableStringBuilder.getSpans(0,
				mSpannableStringBuilder.length(), ParagraphStyle.class);
		for (int i = 0; i < obj.length; i++) {
			int start = mSpannableStringBuilder.getSpanStart(obj[i]);
			int end = mSpannableStringBuilder.getSpanEnd(obj[i]);

			// If the last line of the range is blank, back off by one.
			if (end - 2 >= 0) {
				if (mSpannableStringBuilder.charAt(end - 1) == '\n'
						&& mSpannableStringBuilder.charAt(end - 2) == '\n') {
					end--;
				}
			}

			if (end == start) {
				mSpannableStringBuilder.removeSpan(obj[i]);
			} else {
				mSpannableStringBuilder.setSpan(obj[i], start, end,
						Spannable.SPAN_PARAGRAPH);
			}
		}

		return mSpannableStringBuilder;
	}

	private void handleStartTag(String tag, Attributes attributes) {
		if (tag.equalsIgnoreCase("br")) {
			// We don't need to handle this. TagSoup will ensure that there's a
			// </br> for each <br>
			// so we can safely emite the linebreaks when we handle the close
			// tag.
		} else if (tag.equalsIgnoreCase("p")) {
			handleP(mSpannableStringBuilder);
		} else if (tag.equalsIgnoreCase("div")) {
			handleP(mSpannableStringBuilder);
		} else if (tag.equalsIgnoreCase("strong")) {
			start(mSpannableStringBuilder, new Bold());
		} else if (tag.equalsIgnoreCase("b")) {
			start(mSpannableStringBuilder, new Bold());
		} else if (tag.equalsIgnoreCase("em")) {
			start(mSpannableStringBuilder, new Em());
		} else if (tag.equalsIgnoreCase("cite")) {
			start(mSpannableStringBuilder, new Italic());
		} else if (tag.equalsIgnoreCase("dfn")) {
			start(mSpannableStringBuilder, new Italic());
		} else if (tag.equalsIgnoreCase("i")) {
			start(mSpannableStringBuilder, new Italic());
		} else if (tag.equalsIgnoreCase("big")) {
			start(mSpannableStringBuilder, new Big());
		} else if (tag.equalsIgnoreCase("small")) {
			start(mSpannableStringBuilder, new Small());
		} else if (tag.equalsIgnoreCase("font")) {
			startFont(mSpannableStringBuilder, attributes);
		} else if (tag.equalsIgnoreCase("blockquote")) {
			handleP(mSpannableStringBuilder);
			start(mSpannableStringBuilder, new Blockquote());
		} else if (tag.equalsIgnoreCase("tt")) {
			start(mSpannableStringBuilder, new Monospace());
		} else if (tag.equalsIgnoreCase("a")) {
			startA(mSpannableStringBuilder, attributes);
		} else if (tag.equalsIgnoreCase("u")) {
			start(mSpannableStringBuilder, new Underline());
		} else if (tag.equalsIgnoreCase("sup")) {
			start(mSpannableStringBuilder, new Super());
		} else if (tag.equalsIgnoreCase("sub")) {
			start(mSpannableStringBuilder, new Sub());
		} else if (tag.length() == 2
				&& Character.toLowerCase(tag.charAt(0)) == 'h'
				&& tag.charAt(1) >= '1' && tag.charAt(1) <= '6') {
			handleP(mSpannableStringBuilder);
			start(mSpannableStringBuilder, new Header(tag.charAt(1) - '1'));
		} else if (tag.equalsIgnoreCase("img")) {
			startImg(mSpannableStringBuilder, attributes, mImageGetter);
		} else if (mTagHandler != null) {
			mTagHandler.handleTag(true, tag, mSpannableStringBuilder, mReader);
		}
	}

	private void handleEndTag(String tag) {
		if (tag.equalsIgnoreCase("br")) {
			handleBr(mSpannableStringBuilder);
		} else if (tag.equalsIgnoreCase("p")) {
			handleP(mSpannableStringBuilder);
		} else if (tag.equalsIgnoreCase("div")) {
			handleP(mSpannableStringBuilder);
		} else if (tag.equalsIgnoreCase("strong")) {
			end(mSpannableStringBuilder, Bold.class, new StyleSpan(
					Typeface.BOLD));
		} else if (tag.equalsIgnoreCase("b")) {
			end(mSpannableStringBuilder, Bold.class, new StyleSpan(
					Typeface.BOLD));
		} else if (tag.equalsIgnoreCase("em")) {
			endEm(mSpannableStringBuilder);
		} else if (tag.equalsIgnoreCase("cite")) {
			end(mSpannableStringBuilder, Italic.class, new StyleSpan(
					Typeface.ITALIC));
		} else if (tag.equalsIgnoreCase("dfn")) {
			end(mSpannableStringBuilder, Italic.class, new StyleSpan(
					Typeface.ITALIC));
		} else if (tag.equalsIgnoreCase("i")) {
			end(mSpannableStringBuilder, Italic.class, new StyleSpan(
					Typeface.ITALIC));
		} else if (tag.equalsIgnoreCase("big")) {
			end(mSpannableStringBuilder, Big.class, new RelativeSizeSpan(1.25f));
		} else if (tag.equalsIgnoreCase("small")) {
			end(mSpannableStringBuilder, Small.class,
					new RelativeSizeSpan(0.8f));
		} else if (tag.equalsIgnoreCase("font")) {
			endFont(mSpannableStringBuilder);
		} else if (tag.equalsIgnoreCase("blockquote")) {
			handleP(mSpannableStringBuilder);
			end(mSpannableStringBuilder, Blockquote.class, new QuoteSpan());
		} else if (tag.equalsIgnoreCase("tt")) {
			end(mSpannableStringBuilder, Monospace.class, new TypefaceSpan(
					"monospace"));
		} else if (tag.equalsIgnoreCase("a")) {
			endA(mSpannableStringBuilder);
		} else if (tag.equalsIgnoreCase("u")) {
			end(mSpannableStringBuilder, Underline.class, new UnderlineSpan());
		} else if (tag.equalsIgnoreCase("sup")) {
			end(mSpannableStringBuilder, Super.class, new SuperscriptSpan());
		} else if (tag.equalsIgnoreCase("sub")) {
			end(mSpannableStringBuilder, Sub.class, new SubscriptSpan());
		} else if (tag.length() == 2
				&& Character.toLowerCase(tag.charAt(0)) == 'h'
				&& tag.charAt(1) >= '1' && tag.charAt(1) <= '6') {
			handleP(mSpannableStringBuilder);
			endHeader(mSpannableStringBuilder);
		} else if (mTagHandler != null) {
			mTagHandler.handleTag(false, tag, mSpannableStringBuilder, mReader);
		}
	}

	private static void handleP(SpannableStringBuilder text) {
		int len = text.length();

		if (len >= 1 && text.charAt(len - 1) == '\n') {
			if (len >= 2 && text.charAt(len - 2) == '\n') {
				return;
			}

			text.append("\n");
			return;
		}

		if (len != 0) {
			text.append("\n\n");
		}
	}

	private static void handleBr(SpannableStringBuilder text) {
		text.append("\n");
	}

	private static Object getLast(Spanned text, Class kind) {
		/*
		 * This knows that the last returned object from getSpans() will be the
		 * most recently added.
		 */
		Object[] objs = text.getSpans(0, text.length(), kind);

		if (objs.length == 0) {
			return null;
		} else {
			return objs[objs.length - 1];
		}
	}

	private static void start(SpannableStringBuilder text, Object mark) {
		int len = text.length();
		text.setSpan(mark, len, len, Spannable.SPAN_MARK_MARK);
	}

	private static void end(SpannableStringBuilder text, Class kind, Object repl) {
		int len = text.length();
		Object obj = getLast(text, kind);
		int where = text.getSpanStart(obj);

		text.removeSpan(obj);

		if (where != len) {
			text.setSpan(repl, where, len, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
		}

		return;
	}

	private static void startImg(SpannableStringBuilder text,
			Attributes attributes, Html.ImageGetter img) {
		String src = attributes.getValue("", "src");
		Drawable d = null;
		if (img != null) {
			d = img.getDrawable(src);
		}
		if (d == null) {
			d = Html.getContext().getResources()
					.getDrawable(R.drawable.unknown_image);
		}
		d.setBounds(0, 0, d.getIntrinsicWidth(), d.getIntrinsicHeight());

		text.append("\n");
		int len = text.length();
		text.append("\uFFFC");
		text.setSpan(new ImageSpan(d, src), len, text.length(),
				Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
		text.append("\n");
	}

	private static void startFont(SpannableStringBuilder text,
			Attributes attributes) {
		String color = attributes.getValue("", "color");
		String face = attributes.getValue("", "face");

		int len = text.length();
		text.setSpan(new Font(color, face), len, len, Spannable.SPAN_MARK_MARK);
	}
	
	private static void endFont(SpannableStringBuilder text) {
		int len = text.length();
		Object obj = getLast(text, Font.class);
		int where = text.getSpanStart(obj);

		text.removeSpan(obj);

		if (where != len) {
			Font f = (Font) obj;

			if (!TextUtils.isEmpty(f.mColor)) {
				if (f.mColor.startsWith("@")) {
					Resources res = Resources.getSystem();
					String name = f.mColor.substring(1);
					int colorRes = res.getIdentifier(name, "color", "android");
					if (colorRes != 0) {
						ColorStateList colors = res.getColorStateList(colorRes);
						text.setSpan(new TextAppearanceSpan(null, 0, 0, colors,
								null), where, len,
								Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
					}
				} else {
					int c = getHtmlColor(f.mColor);
					if (c != -1) {
						text.setSpan(new ForegroundColorSpan(c | 0xFF000000),
								where, len, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
					}
				}
			}

			if (f.mFace != null) {
				text.setSpan(new TypefaceSpan(f.mFace), where, len,
						Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
			}
		}
	}
	
	private static void endEm(SpannableStringBuilder text) {
		int len = text.length();
		Object obj = getLast(text, Em.class);
		int where = text.getSpanStart(obj);

		text.removeSpan(obj);
		if (where != len) {
			final String content = text.subSequence(where, len).toString();
			text.setSpan(
					EmojiConversionUtil
							.getInstace(Html.getContext())
							.dealExpression(content, Html.getEmSize()), where, len,
					Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
		}
	}

	private static void startA(SpannableStringBuilder text,
			Attributes attributes) {
		String href = attributes.getValue("", "href");

		int len = text.length();
		text.setSpan(new Href(href), len, len, Spannable.SPAN_MARK_MARK);
	}

	private static void endA(SpannableStringBuilder text) {
		int len = text.length();
		Object obj = getLast(text, Href.class);
		int where = text.getSpanStart(obj);

		text.removeSpan(obj);

		if (where != len) {
			Href h = (Href) obj;

			if (h.mHref != null) {
				text.setSpan(new AdvancedUrlSpan(h.mHref), where, len,
						Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
			}
		}
	}

	private static void endHeader(SpannableStringBuilder text) {
		int len = text.length();
		Object obj = getLast(text, Header.class);

		int where = text.getSpanStart(obj);

		text.removeSpan(obj);

		// Back off not to change only the text, not the blank line.
		while (len > where && text.charAt(len - 1) == '\n') {
			len--;
		}

		if (where != len) {
			Header h = (Header) obj;

			text.setSpan(new RelativeSizeSpan(HEADER_SIZES[h.mLevel]), where,
					len, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
			text.setSpan(new StyleSpan(Typeface.BOLD), where, len,
					Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
		}
	}

	public void setDocumentLocator(Locator locator) {
	}

	public void startDocument() throws SAXException {
	}

	public void endDocument() throws SAXException {
	}

	public void startPrefixMapping(String prefix, String uri)
			throws SAXException {
	}

	public void endPrefixMapping(String prefix) throws SAXException {
	}

	public void startElement(String uri, String localName, String qName,
			Attributes attributes) throws SAXException {
		handleStartTag(localName, attributes);
	}

	public void endElement(String uri, String localName, String qName)
			throws SAXException {
		handleEndTag(localName);
	}

	public void characters(char ch[], int start, int length)
			throws SAXException {
		StringBuilder sb = new StringBuilder();

		/*
		 * Ignore whitespace that immediately follows other whitespace; newlines
		 * count as spaces.
		 */
		for (int i = 0; i < length; i++) {
			char c = ch[i + start];
			
//			if (c == ' ' || c == '\n') {
//				char pred;
//				int len = sb.length();
//
//				if (len == 0) {
//					len = mSpannableStringBuilder.length();
//
//					if (len == 0) {
//						pred = '\n';
//					} else {
//						pred = mSpannableStringBuilder.charAt(len - 1);
//					}
//				} else {
//					pred = sb.charAt(len - 1);
//				}
//
//				if (pred != ' ' && pred != '\n') {
//					sb.append(' ');
//				}
//			} else {
//				sb.append(c);
//			}
			sb.append(c);
		}

		mSpannableStringBuilder.append(sb);
	}

	public void ignorableWhitespace(char ch[], int start, int length)
			throws SAXException {
	}

	public void processingInstruction(String target, String data)
			throws SAXException {
	}

	public void skippedEntity(String name) throws SAXException {
	}
	
	private static class Em {
	}

	private static class Bold {
	}

	private static class Italic {
	}

	private static class Underline {
	}

	private static class Big {
	}

	private static class Small {
	}

	private static class Monospace {
	}

	private static class Blockquote {
	}

	private static class Super {
	}

	private static class Sub {
	}

	private static class Font {
		public String mColor;
		public String mFace;

		public Font(String color, String face) {
			mColor = color;
			mFace = face;
		}
	}

	private static class Href {
		public String mHref;

		public Href(String href) {
			mHref = href;
		}
	}

	private static class Header {
		private int mLevel;

		public Header(int level) {
			mLevel = level;
		}
	}

	private static HashMap<String, Integer> COLORS = buildColorMap();

	private static HashMap<String, Integer> buildColorMap() {
		HashMap<String, Integer> map = new HashMap<String, Integer>();
		map.put("aqua", 0x00FFFF);
		map.put("black", 0x000000);
		map.put("blue", 0x0000FF);
		map.put("fuchsia", 0xFF00FF);
		map.put("green", 0x008000);
		map.put("grey", 0x808080);
		map.put("lime", 0x00FF00);
		map.put("maroon", 0x800000);
		map.put("navy", 0x000080);
		map.put("olive", 0x808000);
		map.put("purple", 0x800080);
		map.put("red", 0xFF0000);
		map.put("silver", 0xC0C0C0);
		map.put("teal", 0x008080);
		map.put("white", 0xFFFFFF);
		map.put("yellow", 0xFFFF00);
		return map;
	}

	/**
	 * Converts an HTML color (named or numeric) to an integer RGB value.
	 *
	 * @param color
	 *            Non-null color string.
	 * @return A color value, or {@code -1} if the color string could not be
	 *         interpreted.
	 */
	private static int getHtmlColor(String color) {
		Integer i = COLORS.get(color.toLowerCase());
		if (i != null) {
			return i;
		} else {
			try {
				return XmlUtils.convertValueToInt(color, -1);
			} catch (NumberFormatException nfe) {
				return -1;
			}
		}
	}

}