Create Accessible Scrollable control - Java Swing

Description

Create Accessible Scrollable control

Demo Code

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.*;

import java.awt.*;
import javax.swing.*;
import javax.accessibility.*;
import java.awt.*;
import javax.swing.*;
import javax.accessibility.*;
import java.util.Locale;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.*;

/* ScrollablePicture.java is used by AccessibleScrollDemo.java. */

class ScrollablePicture extends JLabel implements Scrollable {

    private int maxUnitIncrement = 1;
    private boolean missingPicture = false;

    public ScrollablePicture(ImageIcon i, int m) {
        super(i);
        if (i == null) {
            missingPicture = true;/*from   w ww.j  a  v a2 s.c  om*/
            setText("No picture found.");
            setHorizontalAlignment(CENTER);
            setOpaque(true);
            setBackground(Color.white);
        }
        maxUnitIncrement = m;
    }

    public Dimension getPreferredSize() {
        if (missingPicture) {
            return new Dimension(320, 480);
        } else {
            return super.getPreferredSize();
        }
    }

    public Dimension getPreferredScrollableViewportSize() {
        return getPreferredSize();
    }

    public int getScrollableUnitIncrement(Rectangle visibleRect,
            int orientation, int direction) {
        //Get the current position.
        int currentPosition = 0;
        if (orientation == SwingConstants.HORIZONTAL) {
            currentPosition = visibleRect.x;
        } else {
            currentPosition = visibleRect.y;
        }

        //Return the number of pixels between currentPosition
        //and the nearest tick mark in the indicated direction.
        if (direction < 0) {
            int newPosition = currentPosition
                    - (currentPosition / maxUnitIncrement)
                    * maxUnitIncrement;
            return (newPosition == 0) ? maxUnitIncrement : newPosition;
        } else {
            return ((currentPosition / maxUnitIncrement) + 1)
                    * maxUnitIncrement - currentPosition;
        }
    }

    public int getScrollableBlockIncrement(Rectangle visibleRect,
            int orientation, int direction) {
        if (orientation == SwingConstants.HORIZONTAL) {
            return visibleRect.width - maxUnitIncrement;
        } else {
            return visibleRect.height - maxUnitIncrement;
        }
    }

    public boolean getScrollableTracksViewportWidth() {
        return false;
    }

    public boolean getScrollableTracksViewportHeight() {
        return false;
    }

    public void setMaxUnitIncrement(int pixels) {
        maxUnitIncrement = pixels;
    }
}

/* Rule.java is used by AccessibleScrollDemo.java. */

class Rule extends JComponent implements Accessible {
    public static final int INCH = Toolkit.getDefaultToolkit()
            .getScreenResolution();
    public static final int HORIZONTAL = 0;
    public static final int VERTICAL = 1;
    public static final int SIZE = 35;

    public int orientation;
    public boolean isMetric;
    private int increment;
    private int units;

    public Rule(int o, boolean m) {
        orientation = o;
        isMetric = m;
        setIncrementAndUnits();
    }

    public void setIsMetric(boolean isMetric) {
        if (accessibleContext != null && this.isMetric != isMetric) {
            if (isMetric) {
                accessibleContext.firePropertyChange(
                        AccessibleContext.ACCESSIBLE_STATE_PROPERTY,
                        AccessibleRulerState.INCHES,
                        AccessibleRulerState.CENTIMETERS);
            } else {
                accessibleContext.firePropertyChange(
                        AccessibleContext.ACCESSIBLE_STATE_PROPERTY,
                        AccessibleRulerState.CENTIMETERS,
                        AccessibleRulerState.INCHES);
            }
        }
        this.isMetric = isMetric;
        setIncrementAndUnits();
        repaint();
    }

    private void setIncrementAndUnits() {
        if (isMetric) {
            units = (int) ((double) INCH / (double) 2.54); // dots per centimeter
            increment = units;
        } else {
            units = INCH;
            increment = units / 2;
        }
    }

    public boolean isMetric() {
        return this.isMetric;
    }

    public int getIncrement() {
        return increment;
    }

    public void setPreferredHeight(int ph) {
        setPreferredSize(new Dimension(SIZE, ph));
    }

    public void setPreferredWidth(int pw) {
        setPreferredSize(new Dimension(pw, SIZE));
    }

    protected void paintComponent(Graphics g) {
        Rectangle drawHere = g.getClipBounds();

        // Fill clipping area with dirty brown/orange.
        g.setColor(new Color(230, 163, 4));
        g.fillRect(drawHere.x, drawHere.y, drawHere.width, drawHere.height);

        // Do the ruler labels in a small font that's black.
        g.setFont(new Font("SansSerif", Font.PLAIN, 10));
        g.setColor(Color.black);

        // Some vars we need.
        int end = 0;
        int start = 0;
        int tickLength = 0;
        String text = null;

        // Use clipping bounds to calculate first and last tick locations.
        if (orientation == HORIZONTAL) {
            start = (drawHere.x / increment) * increment;
            end = (((drawHere.x + drawHere.width) / increment) + 1)
                    * increment;
        } else {
            start = (drawHere.y / increment) * increment;
            end = (((drawHere.y + drawHere.height) / increment) + 1)
                    * increment;
        }

        // Make a special case of 0 to display the number
        // within the rule and draw a units label.
        if (start == 0) {
            text = Integer.toString(0) + (isMetric ? " cm" : " in");
            tickLength = 10;
            if (orientation == HORIZONTAL) {
                g.drawLine(0, SIZE - 1, 0, SIZE - tickLength - 1);
                g.drawString(text, 2, 21);
            } else {
                g.drawLine(SIZE - 1, 0, SIZE - tickLength - 1, 0);
                g.drawString(text, 9, 10);
            }
            text = null;
            start = increment;
        }

        // ticks and labels
        for (int i = start; i < end; i += increment) {
            if (i % units == 0) {
                tickLength = 10;
                text = Integer.toString(i / units);
            } else {
                tickLength = 7;
                text = null;
            }

            if (tickLength != 0) {
                if (orientation == HORIZONTAL) {
                    g.drawLine(i, SIZE - 1, i, SIZE - tickLength - 1);
                    if (text != null)
                        g.drawString(text, i - 3, 21);
                } else {
                    g.drawLine(SIZE - 1, i, SIZE - tickLength - 1, i);
                    if (text != null)
                        g.drawString(text, 9, i + 3);
                }
            }
        }
    }

    public AccessibleContext getAccessibleContext() {
        if (accessibleContext == null) {
            accessibleContext = new AccessibleRuler();
        }
        return accessibleContext;
    }

    protected class AccessibleRuler extends AccessibleJComponent {
        public AccessibleRole getAccessibleRole() {
            return AccessibleRuleRole.RULER;
        }

        public AccessibleStateSet getAccessibleStateSet() {
            AccessibleStateSet states = super.getAccessibleStateSet();
            if (orientation == VERTICAL) {
                states.add(AccessibleState.VERTICAL);
            } else {
                states.add(AccessibleState.HORIZONTAL);
            }
            if (isMetric) {
                states.add(AccessibleRulerState.CENTIMETERS);
            } else {
                states.add(AccessibleRulerState.INCHES);
            }
            return states;
        }
    }
}

class AccessibleRuleRole extends AccessibleRole {
    public static final AccessibleRuleRole RULER = new AccessibleRuleRole(
            "ruler");

    protected AccessibleRuleRole(String key) {
        super(key);
    }

    //Should really provide localizable versions of these names.
    public String toDisplayString(String resourceBundleName, Locale locale) {
        return key;
    }
}

class AccessibleRulerState extends AccessibleState {
    public static final AccessibleRulerState INCHES = new AccessibleRulerState(
            "inches");
    public static final AccessibleRulerState CENTIMETERS = new AccessibleRulerState(
            "centimeters");

    protected AccessibleRulerState(String key) {
        super(key);
    }

    //Should really provide localizable versions of these names.
    public String toDisplayString(String resourceBundleName, Locale locale) {
        return key;
    }
}

/* Corner.java is used by AccessibleScrollDemo.java. */

class Corner extends JComponent implements Accessible {
    protected void paintComponent(Graphics g) {
        // Fill me with dirty brown/orange.
        g.setColor(new Color(230, 163, 4));
        g.fillRect(0, 0, getWidth(), getHeight());
    }

    public AccessibleContext getAccessibleContext() {
        if (accessibleContext == null) {
            accessibleContext = new AccessibleCorner();
        }
        return accessibleContext;
    }

    protected class AccessibleCorner extends AccessibleJComponent {
        //Inherit everything, override nothing.
    }
}
/*
 * AccessibleScrollDemo requires these files:
 *    Rule.java
 *    Corner.java
 *    ScrollablePicture.java
 *    images/flyingBee.jpg
 */
public class AccessibleScrollDemo extends JPanel implements ItemListener {
    private Rule columnView;
    private Rule rowView;

    private JToggleButton isMetric;
    private ScrollablePicture picture;

    public AccessibleScrollDemo() {
        // Get the image to use.
        ImageIcon bee = createImageIcon("images/flyingBee.jpg",
                "Photograph of a flying bee.");

        // Create the row and column headers.
        columnView = new Rule(Rule.HORIZONTAL, true);
        if (bee != null) {
            columnView.setPreferredWidth(bee.getIconWidth());
        } else {
            columnView.setPreferredWidth(320);
        }
        columnView.getAccessibleContext()
                .setAccessibleName("Column Header");
        columnView.getAccessibleContext().setAccessibleDescription(
                "Displays horizontal ruler for "
                        + "measuring scroll pane client.");
        rowView = new Rule(Rule.VERTICAL, true);
        if (bee != null) {
            rowView.setPreferredHeight(bee.getIconHeight());
        } else {
            rowView.setPreferredHeight(480);
        }
        rowView.getAccessibleContext().setAccessibleName("Row Header");
        rowView.getAccessibleContext().setAccessibleDescription(
                "Displays vertical ruler for "
                        + "measuring scroll pane client.");

        // Create the corners.
        JPanel buttonCorner = new JPanel();
        isMetric = new JToggleButton("cm", true);
        isMetric.setFont(new Font("SansSerif", Font.PLAIN, 11));
        isMetric.setMargin(new Insets(2, 2, 2, 2));
        isMetric.addItemListener(this);
        isMetric.setToolTipText("Toggles rulers' unit of measure "
                + "between inches and centimeters.");
        buttonCorner.add(isMetric); //Use the default FlowLayout
        buttonCorner.getAccessibleContext().setAccessibleName(
                "Upper Left Corner");

        String desc = "Fills the corner of a scroll pane "
                + "with color for aesthetic reasons.";
        Corner lowerLeft = new Corner();
        lowerLeft.getAccessibleContext().setAccessibleName(
                "Lower Left Corner");
        lowerLeft.getAccessibleContext().setAccessibleDescription(desc);

        Corner upperRight = new Corner();
        upperRight.getAccessibleContext().setAccessibleName(
                "Upper Right Corner");
        upperRight.getAccessibleContext().setAccessibleDescription(desc);

        // Set up the scroll pane.
        picture = new ScrollablePicture(bee, columnView.getIncrement());
        picture.setToolTipText(bee.getDescription());
        picture.getAccessibleContext().setAccessibleName(
                "Scroll pane client");

        JScrollPane pictureScrollPane = new JScrollPane(picture);
        pictureScrollPane.setPreferredSize(new Dimension(300, 250));
        pictureScrollPane.setViewportBorder(BorderFactory
                .createLineBorder(Color.black));

        pictureScrollPane.setColumnHeaderView(columnView);
        pictureScrollPane.setRowHeaderView(rowView);

        // In theory, to support internationalization you would change
        // UPPER_LEFT_CORNER to UPPER_LEADING_CORNER,
        // LOWER_LEFT_CORNER to LOWER_LEADING_CORNER, and
        // UPPER_RIGHT_CORNER to UPPER_TRAILING_CORNER.  In practice,
        // bug #4467063 makes that impossible (at least in 1.4.0).
        pictureScrollPane.setCorner(JScrollPane.UPPER_LEFT_CORNER,
                buttonCorner);
        pictureScrollPane.setCorner(JScrollPane.LOWER_LEFT_CORNER,
                lowerLeft);
        pictureScrollPane.setCorner(JScrollPane.UPPER_RIGHT_CORNER,
                upperRight);

        // Put it in this panel.
        setLayout(new BoxLayout(this, BoxLayout.X_AXIS));
        add(pictureScrollPane);
        setBorder(BorderFactory.createEmptyBorder(20, 20, 20, 20));
    }

    public void itemStateChanged(ItemEvent e) {
        if (e.getStateChange() == ItemEvent.SELECTED) {
            // Turn it to metric.
            rowView.setIsMetric(true);
            columnView.setIsMetric(true);
        } else {
            // Turn it to inches.
            rowView.setIsMetric(false);
            columnView.setIsMetric(false);
        }
        picture.setMaxUnitIncrement(rowView.getIncrement());
    }

    /** Returns an ImageIcon, or null if the path was invalid. */
    protected static ImageIcon createImageIcon(String path,
            String description) {
        java.net.URL imgURL = AccessibleScrollDemo.class.getResource(path);
        if (imgURL != null) {
            return new ImageIcon(imgURL, description);
        } else {
            System.err.println("Couldn't find file: " + path);
            return null;
        }
    }

    /**
     * Create the GUI and show it.  For thread safety,
     * this method should be invoked from the
     * event-dispatching thread.
     */
    private static void createAndShowGUI() {
        //Create and set up the window.
        JFrame frame = new JFrame("AccessibleScrollDemo");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        //Create and set up the content pane.
        JComponent newContentPane = new AccessibleScrollDemo();
        newContentPane.setOpaque(true); //content panes must be opaque
        frame.setContentPane(newContentPane);

        //Display the window.
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        //Schedule a job for the event-dispatching thread:
        //creating and showing this application's GUI.
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }
}

/*
 * Copyright (c) 1995, 2011, Oracle and/or its affiliates. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *   - Neither the name of Oracle or the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

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