/*

 * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package javax.swing.text.html;

import java.awt.Rectangle;

import java.awt.Image;

import java.awt.Container;

import java.awt.Color;

import java.awt.Shape;

import java.awt.Graphics;

import java.awt.Toolkit;

import java.awt.image.ImageObserver;

import java.net.URL;

import java.net.MalformedURLException;

import java.util.Dictionary;

import javax.swing.GrayFilter;

import javax.swing.ImageIcon;

import javax.swing.Icon;

import javax.swing.UIManager;

import javax.swing.SwingUtilities;

import javax.swing.text.JTextComponent;

import javax.swing.text.StyledDocument;

import javax.swing.text.View;

import javax.swing.text.AttributeSet;

import javax.swing.text.Element;

import javax.swing.text.ViewFactory;

import javax.swing.text.Position;

import javax.swing.text.Segment;

import javax.swing.text.Highlighter;

import javax.swing.text.LayeredHighlighter;

import javax.swing.text.AbstractDocument;

import javax.swing.text.Document;

import javax.swing.text.BadLocationException;

import javax.swing.event.DocumentEvent;

/**

 * View of an Image, intended to support the HTML <IMG> tag.

 * Supports scaling via the HEIGHT and WIDTH attributes of the tag.

 * If the image is unable to be loaded any text specified via the

 * <code>ALT</code> attribute will be rendered.

 * <p>

 * While this class has been part of swing for a while now, it is public

 * as of 1.4.

 *

 * @author  Scott Violet

 * @see IconView

 * @since 1.4

 */

public class ImageView extends View {

    /**

     * If true, when some of the bits are available a repaint is done.

     * <p>

     * This is set to false as swing does not offer a repaint that takes a

     * delay. If this were true, a bunch of immediate repaints would get

     * generated that end up significantly delaying the loading of the image

     * (or anything else going on for that matter).

     */

    private static boolean sIsInc = false;

    /**

     * Repaint delay when some of the bits are available.

     */

    private static int sIncRate = 100;

    /**

     * Property name for pending image icon

     */

    private static final String PENDING_IMAGE = "html.pendingImage";

    /**

     * Property name for missing image icon

     */

    private static final String MISSING_IMAGE = "html.missingImage";

    /**

     * Document property for image cache.

     */

    private static final String IMAGE_CACHE_PROPERTY = "imageCache";

    // Height/width to use before we know the real size, these should at least

    // the size of <code>sMissingImageIcon</code> and

    // <code>sPendingImageIcon</code>

    private static final int DEFAULT_WIDTH = 38;

    private static final int DEFAULT_HEIGHT= 38;

    /**

     * Default border to use if one is not specified.

     */

    private static final int DEFAULT_BORDER = 2;

    // Bitmask values

    private static final int LOADING_FLAG = 1;

    private static final int LINK_FLAG = 2;

    private static final int WIDTH_FLAG = 4;

    private static final int HEIGHT_FLAG = 8;

    private static final int RELOAD_FLAG = 16;

    private static final int RELOAD_IMAGE_FLAG = 32;

    private static final int SYNC_LOAD_FLAG = 64;

    private AttributeSet attr;

    private Image image;

    private Image disabledImage;

    private int width;

    private int height;

    /** Bitmask containing some of the above bitmask values. Because the

     * image loading notification can happen on another thread access to

     * this is synchronized (at least for modifying it). */

    private int state;

    private Container container;

    private Rectangle fBounds;

    private Color borderColor;

    // Size of the border, the insets contains this valid. For example, if

    // the HSPACE attribute was 4 and BORDER 2, leftInset would be 6.

    private short borderSize;

    // Insets, obtained from the painter.

    private short leftInset;

    private short rightInset;

    private short topInset;

    private short bottomInset;

    /**

     * We don't directly implement ImageObserver, instead we use an instance

     * that calls back to us.

     */

    private ImageObserver imageObserver;

    /**

     * Used for alt text. Will be non-null if the image couldn't be found,

     * and there is valid alt text.

     */

    private View altView;

    /** Alignment along the vertical (Y) axis. */

    private float vAlign;

    /**

     * Creates a new view that represents an IMG element.

     *

     * @param elem the element to create a view for

     */

    public ImageView(Element elem) {

        super(elem);

        fBounds = new Rectangle();

        imageObserver = new ImageHandler();

        state = RELOAD_FLAG | RELOAD_IMAGE_FLAG;

    }

    /**

     * Returns the text to display if the image cannot be loaded. This is

     * obtained from the Elements attribute set with the attribute name

     * <code>HTML.Attribute.ALT</code>.

     *

     * @return the test to display if the image cannot be loaded.

     */

    public String getAltText() {

        return (String)getElement().getAttributes().getAttribute

            (HTML.Attribute.ALT);

    }

    /**

     * Return a URL for the image source,

     * or null if it could not be determined.

     *

     * @return the URL for the image source, or null if it could not be determined.

     */

    public URL getImageURL() {

        String src = (String)getElement().getAttributes().

                             getAttribute(HTML.Attribute.SRC);

        if (src == null) {

            return null;

        }

        URL reference = ((HTMLDocument)getDocument()).getBase();

        try {

            URL u = new URL(reference,src);

            return u;

        } catch (MalformedURLException e) {

            return null;

        }

    }

    /**

     * Returns the icon to use if the image could not be found.

     *

     * @return the icon to use if the image could not be found.

     */

    public Icon getNoImageIcon() {

        return (Icon) UIManager.getLookAndFeelDefaults().get(MISSING_IMAGE);

    }

    /**

     * Returns the icon to use while in the process of loading the image.

     *

     * @return the icon to use while in the process of loading the image.

     */

    public Icon getLoadingImageIcon() {

        return (Icon) UIManager.getLookAndFeelDefaults().get(PENDING_IMAGE);

    }

    /**

     * Returns the image to render.

     *

     * @return the image to render.

     */

    public Image getImage() {

        sync();

        return image;

    }

    private Image getImage(boolean enabled) {

        Image img = getImage();

        if (! enabled) {

            if (disabledImage == null) {

                disabledImage = GrayFilter.createDisabledImage(img);

            }

            img = disabledImage;

        }

        return img;

    }

    /**

     * Sets how the image is loaded. If <code>newValue</code> is true,

     * the image will be loaded when first asked for, otherwise it will

     * be loaded asynchronously. The default is to not load synchronously,

     * that is to load the image asynchronously.

     *

     * @param newValue if {@code true} the image will be loaded when first asked for,

     *                 otherwise it will be asynchronously.

     */

    public void setLoadsSynchronously(boolean newValue) {

        synchronized(this) {

            if (newValue) {

                state |= SYNC_LOAD_FLAG;

            }

            else {

                state = (state | SYNC_LOAD_FLAG) ^ SYNC_LOAD_FLAG;

            }

        }

    }

    /**

     * Returns {@code true} if the image should be loaded when first asked for.

     *

     * @return {@code true} if the image should be loaded when first asked for.

     */

    public boolean getLoadsSynchronously() {

        return ((state & SYNC_LOAD_FLAG) != 0);

    }

    /**

     * Convenient method to get the StyleSheet.

     *

     * @return the StyleSheet

     */

    protected StyleSheet getStyleSheet() {

        HTMLDocument doc = (HTMLDocument) getDocument();

        return doc.getStyleSheet();

    }

    /**

     * Fetches the attributes to use when rendering.  This is

     * implemented to multiplex the attributes specified in the

     * model with a StyleSheet.

     */

    public AttributeSet getAttributes() {

        sync();

        return attr;

    }

    /**

     * For images the tooltip text comes from text specified with the

     * <code>ALT</code> attribute. This is overriden to return

     * <code>getAltText</code>.

     *

     * @see JTextComponent#getToolTipText

     */

    public String getToolTipText(float x, float y, Shape allocation) {

        return getAltText();

    }

    /**

     * Update any cached values that come from attributes.

     */

    protected void setPropertiesFromAttributes() {

        StyleSheet sheet = getStyleSheet();

        this.attr = sheet.getViewAttributes(this);

        // Gutters

        borderSize = (short)getIntAttr(HTML.Attribute.BORDER, isLink() ?

                                       DEFAULT_BORDER : 0);

        leftInset = rightInset = (short)(getIntAttr(HTML.Attribute.HSPACE,

                                                    0) + borderSize);

        topInset = bottomInset = (short)(getIntAttr(HTML.Attribute.VSPACE,

                                                    0) + borderSize);

        borderColor = ((StyledDocument)getDocument()).getForeground

                      (getAttributes());

        AttributeSet attr = getElement().getAttributes();

        // Alignment.

        // PENDING: This needs to be changed to support the CSS versions

        // when conversion from ALIGN to VERTICAL_ALIGN is complete.

        Object alignment = attr.getAttribute(HTML.Attribute.ALIGN);

        vAlign = 1.0f;

        if (alignment != null) {

            alignment = alignment.toString();

            if ("top".equals(alignment)) {

                vAlign = 0f;

            }

            else if ("middle".equals(alignment)) {

                vAlign = .5f;

            }

        }

        AttributeSet anchorAttr = (AttributeSet)attr.getAttribute(HTML.Tag.A);

        if (anchorAttr != null && anchorAttr.isDefined

            (HTML.Attribute.HREF)) {

            synchronized(this) {

                state |= LINK_FLAG;

            }

        }

        else {

            synchronized(this) {

                state = (state | LINK_FLAG) ^ LINK_FLAG;

            }

        }

    }

    /**

     * Establishes the parent view for this view.

     * Seize this moment to cache the AWT Container I'm in.

     */

    public void setParent(View parent) {

        View oldParent = getParent();

        super.setParent(parent);

        container = (parent != null) ? getContainer() : null;

        if (oldParent != parent) {

            synchronized(this) {

                state |= RELOAD_FLAG;

            }

        }

    }

    /**

     * Invoked when the Elements attributes have changed. Recreates the image.

     */

    public void changedUpdate(DocumentEvent e, Shape a, ViewFactory f) {

        super.changedUpdate(e,a,f);

        synchronized(this) {

            state |= RELOAD_FLAG | RELOAD_IMAGE_FLAG;

        }

        // Assume the worst.

        preferenceChanged(null, true, true);

    }

    /**

     * Paints the View.

     *

     * @param g the rendering surface to use

     * @param a the allocated region to render into

     * @see View#paint

     */

    public void paint(Graphics g, Shape a) {

        sync();

        Rectangle rect = (a instanceof Rectangle) ? (Rectangle)a :

                         a.getBounds();

        Rectangle clip = g.getClipBounds();

        fBounds.setBounds(rect);

        paintHighlights(g, a);

        paintBorder(g, rect);

        if (clip != null) {

            g.clipRect(rect.x + leftInset, rect.y + topInset,

                       rect.width - leftInset - rightInset,

                       rect.height - topInset - bottomInset);

        }

        Container host = getContainer();

        Image img = getImage(host == null || host.isEnabled());

        if (img != null) {

            if (! hasPixels(img)) {

                // No pixels yet, use the default

                Icon icon = getLoadingImageIcon();

                if (icon != null) {

                    icon.paintIcon(host, g,

                            rect.x + leftInset, rect.y + topInset);

                }

            }

            else {

                // Draw the image

                g.drawImage(img, rect.x + leftInset, rect.y + topInset,

                            width, height, imageObserver);

            }

        }

        else {

            Icon icon = getNoImageIcon();

            if (icon != null) {

                icon.paintIcon(host, g,

                        rect.x + leftInset, rect.y + topInset);

            }

            View view = getAltView();

            // Paint the view representing the alt text, if its non-null

            if (view != null && ((state & WIDTH_FLAG) == 0 ||

                                 width > DEFAULT_WIDTH)) {

                // Assume layout along the y direction

                Rectangle altRect = new Rectangle

                    (rect.x + leftInset + DEFAULT_WIDTH, rect.y + topInset,

                     rect.width - leftInset - rightInset - DEFAULT_WIDTH,

                     rect.height - topInset - bottomInset);

                view.paint(g, altRect);

            }

        }

        if (clip != null) {

            // Reset clip.

            g.setClip(clip.x, clip.y, clip.width, clip.height);

        }

    }

    private void paintHighlights(Graphics g, Shape shape) {

        if (container instanceof JTextComponent) {

            JTextComponent tc = (JTextComponent)container;

            Highlighter h = tc.getHighlighter();

            if (h instanceof LayeredHighlighter) {

                ((LayeredHighlighter)h).paintLayeredHighlights

                    (g, getStartOffset(), getEndOffset(), shape, tc, this);

            }

        }

    }

    private void paintBorder(Graphics g, Rectangle rect) {

        Color color = borderColor;

        if ((borderSize > 0 || image == null) && color != null) {

            int xOffset = leftInset - borderSize;

            int yOffset = topInset - borderSize;

            g.setColor(color);

            int n = (image == null) ? 1 : borderSize;

            for (int counter = 0; counter < n; counter++) {

                g.drawRect(rect.x + xOffset + counter,

                           rect.y + yOffset + counter,

                           rect.width - counter - counter - xOffset -xOffset-1,

                           rect.height - counter - counter -yOffset-yOffset-1);

            }

        }

    }

    /**

     * Determines the preferred span for this view along an

     * axis.

     *

     * @param axis may be either X_AXIS or Y_AXIS

     * @return   the span the view would like to be rendered into;

     *           typically the view is told to render into the span

     *           that is returned, although there is no guarantee;

     *           the parent may choose to resize or break the view

     */

    public float getPreferredSpan(int axis) {

        sync();

        // If the attributes specified a width/height, always use it!

        if (axis == View.X_AXIS && (state & WIDTH_FLAG) == WIDTH_FLAG) {

            getPreferredSpanFromAltView(axis);

            return width + leftInset + rightInset;

        }

        if (axis == View.Y_AXIS && (state & HEIGHT_FLAG) == HEIGHT_FLAG) {

            getPreferredSpanFromAltView(axis);

            return height + topInset + bottomInset;

        }

        Image image = getImage();

        if (image != null) {

            switch (axis) {

            case View.X_AXIS:

                return width + leftInset + rightInset;

            case View.Y_AXIS:

                return height + topInset + bottomInset;

            default:

                throw new IllegalArgumentException("Invalid axis: " + axis);

            }

        }

        else {

            View view = getAltView();

            float retValue = 0f;

            if (view != null) {

                retValue = view.getPreferredSpan(axis);

            }

            switch (axis) {

            case View.X_AXIS: