io.wcm.handler.media.markup.ResponsiveImageMediaMarkupBuilder.java Source code

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Here is the source code for io.wcm.handler.media.markup.ResponsiveImageMediaMarkupBuilder.java

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/*
 * #%L
 * wcm.io
 * %%
 * Copyright (C) 2014 wcm.io
 * %%
 * 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.
 * #L%
 */
package io.wcm.handler.media.markup;

import io.wcm.handler.commons.dom.HtmlElement;
import io.wcm.handler.commons.dom.Image;
import io.wcm.handler.media.Asset;
import io.wcm.handler.media.Media;
import io.wcm.handler.media.MediaNameConstants;
import io.wcm.handler.media.Rendition;
import io.wcm.handler.media.format.MediaFormat;

import java.util.Collection;

import org.apache.commons.lang3.StringUtils;
import org.apache.sling.api.SlingHttpServletRequest;
import org.apache.sling.api.resource.Resource;
import org.apache.sling.commons.json.JSONArray;
import org.apache.sling.commons.json.JSONException;
import org.apache.sling.commons.json.JSONObject;
import org.apache.sling.models.annotations.Model;
import org.osgi.annotation.versioning.ConsumerType;

/**
 * Builds image element with data attribute containing sources for responsive image.
 */
@Model(adaptables = { SlingHttpServletRequest.class, Resource.class })
@ConsumerType
public class ResponsiveImageMediaMarkupBuilder extends AbstractImageMediaMarkupBuilder {

    /**
     * Data attribute name for responsive image sources.
     */
    static final String PROP_RESPONSIVE_SOURCES = "resp-src";

    /**
     * Property name for image URL
     */
    static final String PROP_SRC = "src";

    @Override
    public final boolean accepts(Media media) {
        return media.getMediaRequest().getMediaArgs().isMediaFormatsMandatory() && media.getRendition() != null
                && media.getRenditions().size() > 1 && media.isValid();
    }

    @Override
    public final HtmlElement<?> build(Media media) {
        HtmlElement<?> mediaElement = getImageElement(media);

        // set responsive image sources
        JSONArray sources = getResponsiveImageSources(media);
        setResponsiveImageSource(mediaElement, sources, media);

        // set additional attributes
        setAdditionalAttributes(mediaElement, media);

        // further processing in edit or preview mode
        applyWcmMarkup(mediaElement, media);

        return mediaElement;
    }

    /**
     * Create an IMG element with alt text.
     * @param media Media metadata
     * @return IMG element with properties
     */
    protected HtmlElement<?> getImageElement(Media media) {
        Image img = new Image();

        // Alternative text
        Asset asset = media.getAsset();
        String altText = null;
        if (asset != null) {
            altText = asset.getAltText();
        }
        if (StringUtils.isNotEmpty(altText)) {
            img.setAlt(altText);
        }

        return img;
    }

    /**
     * Collect responsive JSON metadata for all renditions as image sources.
     * @param media Media
     * @return JSON metadata
     */
    protected JSONArray getResponsiveImageSources(Media media) {
        Collection<Rendition> renditions = media.getRenditions();
        JSONArray sources = new JSONArray();
        for (Rendition rendition : renditions) {
            sources.put(toReponsiveImageSource(media, rendition));
        }
        return sources;
    }

    /**
     * Build JSON metadata for one rendition as image source.
     * @param media Media
     * @param rendition Rendition
     * @return JSON metadata
     */
    protected JSONObject toReponsiveImageSource(Media media, Rendition rendition) {
        try {
            JSONObject source = new JSONObject();
            MediaFormat mediaFormat = rendition.getMediaFormat();
            source.put(MediaNameConstants.PROP_BREAKPOINT,
                    mediaFormat.getProperties().get(MediaNameConstants.PROP_BREAKPOINT));
            source.put(PROP_SRC, rendition.getUrl());
            return source;
        } catch (JSONException ex) {
            throw new RuntimeException("Error building JSON source.", ex);
        }
    }

    /**
     * Set attribute on media element for responsive image sources
     * @param mediaElement Media element
     * @param responsiveImageSources Responsive image sources JSON metadata
     * @param media Media
     */
    protected void setResponsiveImageSource(HtmlElement<?> mediaElement, JSONArray responsiveImageSources,
            Media media) {
        mediaElement.setData(PROP_RESPONSIVE_SOURCES, responsiveImageSources.toString());
    }

    @Override
    public final boolean isValidMedia(HtmlElement<?> element) {
        if (element instanceof Image) {
            Image img = (Image) element;
            // if it's a responsive image, we don't need the src attribute set
            return imageSourceIsNotEmpty(img)
                    && !StringUtils.contains(img.getCssClass(), MediaNameConstants.CSS_DUMMYIMAGE);
        }
        return false;
    }

    private boolean imageSourceIsNotEmpty(Image img) {
        String imageSources = img.getData(PROP_RESPONSIVE_SOURCES);
        return StringUtils.isNotBlank(imageSources);
    }

}