tds.itemrenderer.processing.ITSUrlBase64.java Source code

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Here is the source code for tds.itemrenderer.processing.ITSUrlBase64.java

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/*******************************************************************************
 * Educational Online Test Delivery System 
 * Copyright (c) 2014 American Institutes for Research
 *   
 * Distributed under the AIR Open Source License, Version 1.0 
 * See accompanying file AIR-License-1_0.txt or at
 * http://www.smarterapp.org/documents/American_Institutes_for_Research_Open_Source_Software_License.pdf
 ******************************************************************************/
package tds.itemrenderer.processing;

import java.io.File;
import java.io.IOException;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import javax.xml.bind.DatatypeConverter;
import org.apache.commons.io.FileUtils;
import AIR.Common.Utilities.Path;

/**
 * 
 * @author jmambo
 * 
 */

/**
 * Used for resolving img tags into base64.
 * 
 * Remark: This is just for testing and is not production ready.
 */
public class ITSUrlBase64 extends ITSUrlResolver {

    public ITSUrlBase64(String filePath) {
        super(filePath);
    }

    private String replaceHtmlMatch(Matcher matcher) {
        String basePath = _filePath.replace(Path.getFileName(_filePath), "");
        String imageFile = matcher.group("src");
        String imagePath = Path.combine(basePath, imageFile);

        byte[] binaryData = null;
        try {
            binaryData = FileUtils.readFileToByteArray(new File(imagePath));
        } catch (IOException e) {
            throw new ITSDocumentProcessingException(e);
        }

        final String base64Format = "data:image/%s;base64,%s";
        String extension = Path.getExtension(imageFile).replace(".", "");
        String base64 = String.format(base64Format, extension, DatatypeConverter.printBase64Binary(binaryData));

        String imageTag = matcher.group("img");

        Matcher matcher2 = matcher.pattern().matcher(imageTag);
        StringBuilder sb = new StringBuilder(imageTag);
        matcher2.find();
        return sb.replace(matcher2.start(2), matcher2.end(2), base64).toString();

    }

    /**
     * Return the images links in a given URL as an array of Strings.
     * 
     * @param html
     * @param tag
     * @param attribute
     * @return String array of all images on a page
     */
    private String replaceHtmlMatches(String html, String tag, String attribute) {
        final String tagPattern = "(?s)(?<" + tag + "><" + tag + "\\s[^>]*?" + attribute + "\\s*=\\s*['\\\"](?<"
                + attribute + ">[^'\\\"]*?)['\\\"][^>]*?>)";
        Pattern pattern = Pattern.compile(tagPattern, Pattern.CASE_INSENSITIVE);
        Matcher matcher = pattern.matcher(html);
        StringBuffer sb = new StringBuffer();
        while (matcher.find()) {
            matcher.appendReplacement(sb, replaceHtmlMatch(matcher));
        }
        matcher.appendTail(sb);

        return sb.toString();
    }

    /**
     * Sets the URL for images and links (e.x., ELPA audio).
     * 
     * @param content
     *          HTML to fix
     */
    @Override
    public String resolveResourceUrls(String content) {
        return replaceHtmlMatches(content, "img", "src");
    }

}