jitsi/src/net/java/sip/communicator/swing/FitLayout.java

/*
 * SIP Communicator, the OpenSource Java VoIP and Instant Messaging client.
 *
 * Distributable under LGPL license.
 * See terms of license at gnu.org.
 */
package net.java.sip.communicator.swing;

import java.awt.*;

/**
 * Represents a <code>LayoutManager</code> which centers the first
 * <code>Component</code> within its <code>Container</code> and, if the
 * preferred size of the <code>Component</code> is larger than the size of the
 * <code>Container</code>, scales the former within the bounds of the latter
 * while preserving the aspect ratio. <code>FitLayout</code> is appropriate for
 * <code>Container</code>s which display a single image or video
 * <code>Component</code> in its entirety for which preserving the aspect ratio
 * is important.
 * 
 * @author Lubomir Marinov
 */
public class FitLayout
    implements LayoutManager
{

    /*
     * Does nothing because this LayoutManager lays out only the first Component
     * of the parent Container and thus doesn't need String associations.
     */
    public void addLayoutComponent(String name, Component comp)
    {
    }

    /**
     * Gets the first <code>Component</code> of a specific
     * <code>Container</code> if there is such a <code>Component</code>.
     * 
     * @param parent the <code>Container</code> to retrieve the first
     *            <code>Component</code> of
     * @return the first <code>Component</code> of a specific
     *         <code>Container</code> if there is such a <code>Component</code>;
     *         otherwise, <tt>null</tt>
     */
    protected Component getComponent(Container parent)
    {
        Component[] components = parent.getComponents();

        return (components.length > 0) ? components[0] : null;
    }

    protected void layoutComponent(Component component, Rectangle bounds,
        float alignmentX, float alignmentY)
    {
        Dimension componentSize = component.getPreferredSize();
        boolean scale = false;
        double ratio = 1;

        if ((componentSize.width != bounds.width) && (componentSize.width > 0))
        {
            scale = true;
            ratio = bounds.width / (double) componentSize.width;
        }
        if ((componentSize.height != bounds.height)
            && (componentSize.height > 0))
        {
            scale = true;
            ratio =
                Math.min(bounds.height / (double) componentSize.height, ratio);
        }
        if (scale)
        {
            componentSize.width = (int) (componentSize.width * ratio);
            componentSize.height = (int) (componentSize.height * ratio);
        }

        component.setBounds(bounds.x
            + Math.round((bounds.width - componentSize.width) * alignmentX),
            bounds.y
                + Math.round((bounds.height - componentSize.height)
                    * alignmentY), componentSize.width, componentSize.height);
    }

    /*
     * Scales the first Component if its preferred size is larger than the size
     * of its parent Container in order to display the Component in its entirety
     * and then centers it within the display area of the parent.
     */
    public void layoutContainer(Container parent)
    {
        Component component = getComponent(parent);

        if (component != null)
            layoutComponent(component, new Rectangle(parent.getSize()),
                Component.CENTER_ALIGNMENT, Component.CENTER_ALIGNMENT);
    }

    /*
     * Since this LayoutManager lays out only the first Component of the
     * specified parent Container, the minimum size of the Container is the
     * minimum size of the mentioned Component.
     */
    public Dimension minimumLayoutSize(Container parent)
    {
        Component component = getComponent(parent);

        return (component != null) ? component.getMinimumSize()
            : new Dimension(0, 0);
    }

    /*
     * Since this LayoutManager lays out only the first Component of the
     * specified parent Container, the preferred size of the Container is the
     * preferred size of the mentioned Component.
     */
    public Dimension preferredLayoutSize(Container parent)
    {
        Component component = getComponent(parent);

        return (component != null) ? component.getPreferredSize()
            : new Dimension(0, 0);
    }

    /*
     * Does nothing because this LayoutManager lays out only the first Component
     * of the parent Container and thus doesn't need String associations.
     */
    public void removeLayoutComponent(Component comp)
    {
    }
}