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/*
 * This file is part of WebLookAndFeel library.
 *
 * WebLookAndFeel library is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * WebLookAndFeel library 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 for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with WebLookAndFeel library.  If not, see .
 */

package com.alee.laf.viewport;

import com.alee.api.annotations.NotNull;
import com.alee.api.merge.Mergeable;
import com.alee.extended.layout.AbstractLayoutManager;
import com.alee.laf.scroll.layout.ScrollBarSettings;
import com.alee.laf.scroll.layout.ScrollPaneLayout;
import com.thoughtworks.xstream.annotations.XStreamAlias;

import javax.swing.*;
import java.awt.*;
import java.io.Serializable;

/**
 * Replacement for default Swing {@link javax.swing.ViewportLayout} used within {@link JViewport} to layout view.
 * It is added to support some of the {@link ScrollPaneLayout} features for scrollbar placement.
 *
 * @author Mikle Garin
 */
@XStreamAlias ( "ViewportLayout" )
public class ViewportLayout extends AbstractLayoutManager implements Mergeable, Cloneable, Serializable
{
    /**
     * Called by the AWT when the specified container needs to be laid out.
     *
     * @param container the container to lay out
     * @throws AWTError if the target isn't the container specified to the {@code BoxLayout} constructor
     */
    @Override
    public void layoutContainer ( @NotNull final Container container )
    {
        final JViewport viewport = ( JViewport ) container;
        final Component view = viewport.getView ();
        if ( view != null )
        {
            Scrollable scrollableView = null;
            if ( view instanceof Scrollable )
            {
                scrollableView = ( Scrollable ) view;
            }

            /**
             * All of the dimensions below are in view coordinates, except vpSize which we're converting.
             */

            final Dimension viewPrefSize = view.getPreferredSize ();
            final Dimension vpSize = viewport.getSize ();
            final Dimension extentSize = viewport.toViewCoordinates ( vpSize );
            final Dimension viewSize = new Dimension ( viewPrefSize );

            /**
             * Adding extra width/height to the view size whenever it should include hovering scroll bar.
             */
            int vExtend = 0;
            int hExtend = 0;
            final Container scroll = viewport.getParent ();
            if ( scroll instanceof JScrollPane )
            {
                final JScrollPane scrollPane = ( JScrollPane ) scroll;
                if ( viewport == scrollPane.getViewport () )
                {
                    final LayoutManager layout = scrollPane.getLayout ();
                    if ( layout instanceof ScrollPaneLayout )
                    {
                        /**
                         * Vertical scroll bar width.
                         */
                        final ScrollBarSettings vpos = ( ( ScrollPaneLayout ) layout ).getVerticalScrollBarPosition ();
                        if ( vpos.isHovering () && vpos.isExtending () )
                        {
                            final JScrollBar vsb = scrollPane.getVerticalScrollBar ();
                            if ( vsb != null && vsb.isShowing () )
                            {
                                vExtend = vsb.getPreferredSize ().width;
                                viewSize.width += vExtend;
                            }
                        }

                        /**
                         * Horizontal scroll bar height.
                         */
                        final ScrollBarSettings hpos = ( ( ScrollPaneLayout ) layout ).getHorizontalScrollBarPosition ();
                        if ( hpos.isHovering () && hpos.isExtending () )
                        {
                            final JScrollBar hsb = scrollPane.getHorizontalScrollBar ();
                            if ( hsb != null && hsb.isShowing () )
                            {
                                hExtend = hsb.getPreferredSize ().height;
                                viewSize.height += hExtend;
                            }
                        }
                    }
                }
            }

            /**
             * Adjusting view size to match tracked view size.
             */
            if ( scrollableView != null )
            {
                Rectangle oldBounds = null;
                if ( vExtend != 0 || hExtend != 0 )
                {
                    oldBounds = viewport.getBounds ();
                    viewport.setBounds ( oldBounds.x, oldBounds.y, oldBounds.width - vExtend, oldBounds.height - hExtend );
                }

                if ( scrollableView.getScrollableTracksViewportWidth () )
                {
                    viewSize.width = vpSize.width /*- vExtend*/;
                }
                if ( scrollableView.getScrollableTracksViewportHeight () )
                {
                    viewSize.height = vpSize.height /*- hExtend*/;
                }

                // Restore bounds
                if ( oldBounds != null )
                {
                    viewport.setBounds ( oldBounds );
                }
            }

            final Point viewPosition = viewport.getViewPosition ();

            /**
             * If the new viewport size would leave empty space to the right of the view, right justify the view or left justify
             * the view when the width of the view is smaller than the container.
             */
            if ( scrollableView == null || viewport.getParent () == null ||
                    viewport.getParent ().getComponentOrientation ().isLeftToRight () )
            {
                if ( viewPosition.x + extentSize.width > viewSize.width )
                {
                    viewPosition.x = Math.max ( 0, viewSize.width - extentSize.width );
                }
            }
            else
            {
                if ( extentSize.width > viewSize.width )
                {
                    viewPosition.x = viewSize.width - extentSize.width;
                }
                else
                {
                    viewPosition.x = Math.max ( 0, Math.min ( viewSize.width - extentSize.width, viewPosition.x ) );
                }
            }

            /**
             * If the new viewport size would leave empty space below the view, bottom justify the view or top justify the view when
             * the height of the view is smaller than the container.
             */
            if ( viewPosition.y + extentSize.height > viewSize.height )
            {
                viewPosition.y = Math.max ( 0, viewSize.height - extentSize.height );
            }

            /**
             * If we haven't been advised about how the viewports size should change wrt to the viewport, i.e. if the view isn't
             * an instance of Scrollable, then adjust the views size as follows.
             *
             * If the origin of the view is showing and the viewport is bigger than the views preferred size, then make the view
             * the same size as the viewport.
             */
            if ( scrollableView == null )
            {
                if ( viewPosition.x <= 0 && vpSize.width > viewSize.width )
                {
                    // Fix negative view position in RTL orientation
                    viewPosition.x = Math.max ( 0, viewPosition.x );
                    viewSize.width = vpSize.width;
                }
                if ( viewPosition.y == 0 && vpSize.height > viewSize.height )
                {
                    viewSize.height = vpSize.height;
                }
            }

            viewport.setViewPosition ( viewPosition );
            viewport.setViewSize ( viewSize );
        }
    }

    @NotNull
    @Override
    public Dimension preferredLayoutSize ( @NotNull final Container container )
    {
        final JViewport viewport = ( JViewport ) container;
        final Component view = viewport.getView ();

        /**
         * Calculating viewport preferred size.
         */
        final Dimension ps;
        if ( view == null )
        {
            ps = new Dimension ( 0, 0 );
        }
        else if ( view instanceof Scrollable )
        {
            final Scrollable scrollable = ( Scrollable ) view;
            ps = scrollable.getPreferredScrollableViewportSize ();
        }
        else
        {
            ps = view.getPreferredSize ();
        }

        /**
         * Adding extra width/height to the viewport preferred size whenever it should include hovering scroll bar.
         */
        final Container scroll = viewport.getParent ();
        if ( scroll instanceof JScrollPane )
        {
            final JScrollPane scrollPane = ( JScrollPane ) scroll;
            if ( viewport == scrollPane.getViewport () )
            {
                final LayoutManager layout = scrollPane.getLayout ();
                if ( layout instanceof ScrollPaneLayout )
                {
                    /**
                     * Vertical scroll bar width.
                     */
                    final ScrollBarSettings vpos = ( ( ScrollPaneLayout ) layout ).getVerticalScrollBarPosition ();
                    if ( vpos.isHovering () && vpos.isExtending () )
                    {
                        final JScrollBar vsb = scrollPane.getVerticalScrollBar ();
                        if ( vsb != null && vsb.isShowing () )
                        {
                            ps.width += vsb.getPreferredSize ().width;
                        }
                    }

                    /**
                     * Horizontal scroll bar height.
                     */
                    final ScrollBarSettings hpos = ( ( ScrollPaneLayout ) layout ).getHorizontalScrollBarPosition ();
                    if ( hpos.isHovering () && hpos.isExtending () )
                    {
                        final JScrollBar hsb = scrollPane.getHorizontalScrollBar ();
                        if ( hsb != null && hsb.isShowing () )
                        {
                            ps.height += hsb.getPreferredSize ().height;
                        }
                    }
                }
            }
        }

        return ps;
    }

    @NotNull
    @Override
    public Dimension minimumLayoutSize ( @NotNull final Container container )
    {
        return new Dimension ( 4, 4 );
    }

    /**
     * The UI resource version of {@link ViewportLayout}.
     */
    @XStreamAlias ( "ViewportLayout$UIResource" )
    public static final class UIResource extends ViewportLayout implements javax.swing.plaf.UIResource
    {
        /**
         * Implementation is used completely from {@link ViewportLayout}.
         */
    }
}