zkoss/zk

/* Style.java

{{IS_NOTE
    Purpose:
        
    Description:
        
    History:
        Thu Jul 20 15:17:40     2006, Created by tomyeh
}}IS_NOTE

Copyright (C) 2006 Potix Corporation. All Rights Reserved.

{{IS_RIGHT
}}IS_RIGHT
*/
package org.zkoss.zul;

import org.zkoss.lang.Objects;
import org.zkoss.zk.ui.AbstractComponent;
import org.zkoss.zk.ui.Desktop;

/**
 * The style component used to specify CSS styles for the owner desktop.
 *
 * <p>Note: a style component can appear anywhere in a ZUML page, but it
 * affects all components in the same desktop.
 *
 * <p>There are two formats when used in a ZUML page:
 *
 * <p>Method 1: Specify the URL of the CSS file
 * <pre><code>&lt;style src="my.css"/&gt;
 * </code></pre>
 *
 * <p>Method 2: Specify the CSS directly
 * <pre><code>&lt;style&gt;
 * .mycls {
 *  border: 1px outset #777;
 * }
 *&lt;/style&gt;
 * </code></pre>
 *
 * <p>Note: if the src and content properties are both set, the later one
 * overrides the previous one.
 *
 * @author tomyeh
 */
public class Style extends AbstractComponent {
    private String _src;
    /** _src and _content cannot be nonnull at the same time. */
    private String _content;
    private String _media;

    public Style() {
        super.setVisible(false);
    }

    /**
     * @param src the URI of an external style sheet.
     */
    public Style(String src) {
        this();
        setSrc(src);
    }

    /**
     * @param src the URI of an external style sheet.
     * @param media the media dependencies for the style sheet.
     * @since 5.0.3
     */
    public Style(String src, String media) {
        this(src);
        setMedia(media);
    }

    /** Returns the URI of an external style sheet.
     *
     * <p>Default: null.
     */
    public String getSrc() {
        return _src;
    }

    /** Sets the URI of an external style sheet.
     *
     * <p>Calling this method implies setContent(null).
     * In other words, the last invocation of {@link #setSrc} overrides
     * the previous {@link #setContent}, if any.
     *
     * @param src the URI of an external style sheet
     * @see #setContent
     */
    public void setSrc(String src) {
        if (src != null && src.length() == 0)
            src = null;
        if (_content != null || !Objects.equals(_src, src)) {
            _src = src;
            _content = null;
            smartUpdate("src", new EncodedURL());
        }
    }

    /** Returns the media dependencies for this style sheet.
     *
     * <p>Default: null.
     * <p>Refer to <a href="http://www.w3.org/TR/CSS2/media.html">media-depedent style sheet</a> for details.
     * @since 5.0.3
     */
    public String getMedia() {
        return _media;
    }

    /** Sets the media dependencies for this style sheet.
     * <p>Refer to <a href="http://www.w3.org/TR/CSS2/media.html">media-depedent style sheet</a> for details.
     *
     * @param media the media dependencies for this style sheet
     * @since 5.0.3
     */
    public void setMedia(String media) {
        if (media != null && media.length() == 0)
            media = null;
        if (!Objects.equals(_media, media)) {
            _media = media;
            smartUpdate("media", _media);
        }
    }

    /** Returns the content of the style element.
     * By content we mean the CSS rules that will be sent to the client.
     *
     * <p>Default: null.
     *
     * <p>Deriving class can override this method to return whatever
     * it prefers (ignored if null).
     * @since 3.0.0
     */
    public String getContent() {
        return _content;
    }

    /** Sets the content of the style element.
     * By content we mean the CSS rules that will be sent to the client.
     *
     * <p>Calling this method implies setSrc(null).
     * In other words, the last invocation of {@link #setContent} overrides
     * the previous {@link #setSrc}, if any.
     * @since 3.0.0
     * @see #setSrc
     */
    public void setContent(String content) {
        if (content != null && content.length() == 0)
            content = null;

        if (_src != null || !Objects.equals(_content, content)) {
            _content = content;
            _src = null;
            smartUpdate("content", _content);
        }
    }

    //super//
    protected void renderProperties(org.zkoss.zk.ui.sys.ContentRenderer renderer) throws java.io.IOException {
        super.renderProperties(renderer);

        render(renderer, "media", _media);
        final String cnt = getContent();
        if (cnt != null)
            render(renderer, "content", cnt);
        else
            render(renderer, "src", getEncodedURL());
    }

    //Component//
    /** Not allowed. */
    public boolean setVisible(boolean visible) {
        throw new UnsupportedOperationException("style is always invisible");
    }

    /** Not childable. */
    protected boolean isChildable() {
        return false;
    }

    /** Returns the encoded URL of the image (never null).
     */
    private String getEncodedURL() {
        if (_src != null) {
            final Desktop dt = getDesktop();
            if (dt != null)
                return dt.getExecution().encodeURL(_src);
        }
        return "";
    }

    private class EncodedURL implements org.zkoss.zk.au.DeferredValue {
        public Object getValue() {
            return getEncodedURL();
        }
    }
}