https://openjdk.java.net/ 
/*
 * Copyright (c) 2002, 2013, 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.plaf.synth;

import javax.swing.*;
import javax.swing.text.JTextComponent;
import javax.swing.border.*;
import javax.swing.plaf.*;
import javax.swing.plaf.basic.*;

import java.beans.PropertyChangeListener;
import java.beans.PropertyChangeEvent;

import java.awt.*;
import java.awt.event.ContainerListener;
import java.awt.event.ContainerEvent;
import java.awt.event.FocusListener;
import java.awt.event.FocusEvent;


Provides the Synth L&F UI delegate for JScrollPane. 
Author:Scott Violet
Since:1.7
/**
 * Provides the Synth L&F UI delegate for
 * {@link javax.swing.JScrollPane}.
 *
 * @author Scott Violet
 * @since 1.7
 */
public class SynthScrollPaneUI extends BasicScrollPaneUI
                               implements PropertyChangeListener, SynthUI {
    private SynthStyle style;
    private boolean viewportViewHasFocus = false;
    private ViewportViewFocusHandler viewportViewFocusHandler;

    
Creates a new UI object for the given component.

Params:
  • x – component to create UI object for
Returns:the UI object
/**
     * Creates a new UI object for the given component.
     *
     * @param x component to create UI object for
     * @return the UI object
     */
    public static ComponentUI createUI(JComponent x) {
        return new SynthScrollPaneUI();
    }

    
Notifies this UI delegate to repaint the specified component. This method paints the component background, then calls the paint(SynthContext, Graphics) method. 
In general, this method does not need to be overridden by subclasses. All Look and Feel rendering code should reside in the paint method. 
Params:
  • g – the Graphics object used for painting
  • c – the component being painted
See Also:
/**
     * Notifies this UI delegate to repaint the specified component.
     * This method paints the component background, then calls
     * the {@link #paint(SynthContext,Graphics)} method.
     *
     * <p>In general, this method does not need to be overridden by subclasses.
     * All Look and Feel rendering code should reside in the {@code paint} method.
     *
     * @param g the {@code Graphics} object used for painting
     * @param c the component being painted
     * @see #paint(SynthContext,Graphics)
     */
    @Override
    public void update(Graphics g, JComponent c) {
        SynthContext context = getContext(c);

        SynthLookAndFeel.update(context, g);
        context.getPainter().paintScrollPaneBackground(context,
                          g, 0, 0, c.getWidth(), c.getHeight());
        paint(context, g);
        context.dispose();
    }

    
Paints the specified component according to the Look and Feel.

This method is not used by Synth Look and Feel. Painting is handled by the paint(SynthContext, Graphics) method. 
Params:
  • g – the Graphics object used for painting
  • c – the component being painted
See Also:
/**
     * Paints the specified component according to the Look and Feel.
     * <p>This method is not used by Synth Look and Feel.
     * Painting is handled by the {@link #paint(SynthContext,Graphics)} method.
     *
     * @param g the {@code Graphics} object used for painting
     * @param c the component being painted
     * @see #paint(SynthContext,Graphics)
     */
    @Override
    public void paint(Graphics g, JComponent c) {
        SynthContext context = getContext(c);

        paint(context, g);
        context.dispose();
    }

    
Paints the specified component.

Params:
  • context – context for the component being painted
  • g – the Graphics object used for painting
See Also:
/**
     * Paints the specified component.
     *
     * @param context context for the component being painted
     * @param g the {@code Graphics} object used for painting
     * @see #update(Graphics,JComponent)
     */
    protected void paint(SynthContext context, Graphics g) {
        Border vpBorder = scrollpane.getViewportBorder();
        if (vpBorder != null) {
            Rectangle r = scrollpane.getViewportBorderBounds();
            vpBorder.paintBorder(scrollpane, g, r.x, r.y, r.width, r.height);
        }
    }

    
{@inheritDoc}

/**
     * {@inheritDoc}
     */
    @Override
    public void paintBorder(SynthContext context, Graphics g, int x,
                            int y, int w, int h) {
        context.getPainter().paintScrollPaneBorder(context, g, x, y, w, h);
    }

    
{@inheritDoc}

/**
     * {@inheritDoc}
     */
    @Override
    protected void installDefaults(JScrollPane scrollpane) {
        updateStyle(scrollpane);
    }

    private void updateStyle(JScrollPane c) {
        SynthContext context = getContext(c, ENABLED);
        SynthStyle oldStyle = style;

        style = SynthLookAndFeel.updateStyle(context, this);
        if (style != oldStyle) {
            Border vpBorder = scrollpane.getViewportBorder();
            if ((vpBorder == null) ||( vpBorder instanceof UIResource)) {
                scrollpane.setViewportBorder(new ViewportBorder(context));
            }
            if (oldStyle != null) {
                uninstallKeyboardActions(c);
                installKeyboardActions(c);
            }
        }
        context.dispose();
    }

    
{@inheritDoc}

/**
     * {@inheritDoc}
     */
    @Override
    protected void installListeners(JScrollPane c) {
        super.installListeners(c);
        c.addPropertyChangeListener(this);
        if (UIManager.getBoolean("ScrollPane.useChildTextComponentFocus")){
            viewportViewFocusHandler = new ViewportViewFocusHandler();
            c.getViewport().addContainerListener(viewportViewFocusHandler);
            Component view = c.getViewport().getView();
            if (view instanceof JTextComponent) {
                view.addFocusListener(viewportViewFocusHandler);
            }
        }
    }

    
{@inheritDoc}

/**
     * {@inheritDoc}
     */
    @Override
    protected void uninstallDefaults(JScrollPane c) {
        SynthContext context = getContext(c, ENABLED);

        style.uninstallDefaults(context);
        context.dispose();

        if (scrollpane.getViewportBorder() instanceof UIResource) {
            scrollpane.setViewportBorder(null);
        }
    }

    
{@inheritDoc}

/**
     * {@inheritDoc}
     */
    @Override
    protected void uninstallListeners(JComponent c) {
        super.uninstallListeners(c);
        c.removePropertyChangeListener(this);
        if (viewportViewFocusHandler != null) {
            JViewport viewport = ((JScrollPane) c).getViewport();
            viewport.removeContainerListener(viewportViewFocusHandler);
            if (viewport.getView()!= null) {
                viewport.getView().removeFocusListener(viewportViewFocusHandler);
            }
            viewportViewFocusHandler = null;
        }
    }

    
{@inheritDoc}

/**
     * {@inheritDoc}
     */
    @Override
    public SynthContext getContext(JComponent c) {
        return getContext(c, getComponentState(c));
    }

    private SynthContext getContext(JComponent c, int state) {
        return SynthContext.getContext(c, style, state);
    }

    private int getComponentState(JComponent c) {
        int baseState = SynthLookAndFeel.getComponentState(c);
        if (viewportViewFocusHandler!=null && viewportViewHasFocus){
            baseState = baseState | FOCUSED;
        }
        return baseState;
    }

    public void propertyChange(PropertyChangeEvent e) {
        if (SynthLookAndFeel.shouldUpdateStyle(e)) {
            updateStyle(scrollpane);
        }
    }



    private class ViewportBorder extends AbstractBorder implements UIResource {
        private Insets insets;

        ViewportBorder(SynthContext context) {
            this.insets = (Insets)context.getStyle().get(context,
                                            "ScrollPane.viewportBorderInsets");
            if (this.insets == null) {
                this.insets = SynthLookAndFeel.EMPTY_UIRESOURCE_INSETS;
            }
        }

        @Override
        public void paintBorder(Component c, Graphics g, int x, int y,
                            int width, int height) {
            JComponent jc = (JComponent)c;
            SynthContext context = getContext(jc);
            SynthStyle style = context.getStyle();
            if (style == null) {
                assert false: "SynthBorder is being used outside after the " +
                              " UI has been uninstalled";
                return;
            }
            context.getPainter().paintViewportBorder(context, g, x, y, width,
                                                     height);
            context.dispose();
        }

        @Override
        public Insets getBorderInsets(Component c, Insets insets) {
            if (insets == null) {
                return new Insets(this.insets.top, this.insets.left,
                                  this.insets.bottom, this.insets.right);
            }
            insets.top = this.insets.top;
            insets.bottom = this.insets.bottom;
            insets.left = this.insets.left;
            insets.right = this.insets.left;
            return insets;
        }

        @Override
        public boolean isBorderOpaque() {
            return false;
        }
    }

    
Handle keeping track of the viewport's view's focus

/**
     * Handle keeping track of the viewport's view's focus
     */
    private class ViewportViewFocusHandler implements ContainerListener,
            FocusListener{
        public void componentAdded(ContainerEvent e) {
            if (e.getChild() instanceof JTextComponent) {
                e.getChild().addFocusListener(this);
                viewportViewHasFocus = e.getChild().isFocusOwner();
                scrollpane.repaint();
            }
        }

        public void componentRemoved(ContainerEvent e) {
            if (e.getChild() instanceof JTextComponent) {
                e.getChild().removeFocusListener(this);
            }
        }

        public void focusGained(FocusEvent e) {
            viewportViewHasFocus = true;
            scrollpane.repaint();
        }

        public void focusLost(FocusEvent e) {
            viewportViewHasFocus = false;
            scrollpane.repaint();
        }
    }
}