Symantec Visual Cafe for Java 2.5/symantec-visual-cafe-2.5-database-dev-edition.iso/VCafe/Source.bin/StatusScroller.java

Java Source | 1998-03-18 | 17.1 KB | 631 lines

package symantec.itools.awt.util;

import java.applet.*;
import java.beans.PropertyVetoException;
import java.beans.PropertyChangeListener;
import java.beans.VetoableChangeListener;


//  Created and implemented by Levi Brown, Symantec Macintosh Internet Tools.
//     04/11/97    LAB    Checked it in
//     04/17/97    LAB    Changed a few names to comply with Java standards.
//                Added automatic initialization of the applet context in the constructor.
//                Changed the function comment style to comply with JavaDoc standards.
//                Took out some unnecessary code in setAppletContext(Applet a).
//                Reorganized the code, to group public and private methods separately.
//                Removed some unnecessary import statements.
//                Fixed a bug in setAppletContext(Applet a) that could cause a NullPointerException.
//                Added set/getAutoStart(boolean f) to allow the scrolling to occur without a direct call to start().
//                Changed the default state of execute to true, so scrolling would automatically occur.
//     06/02/97    LAB    Updated to Java 1.1

/**
 * Displays a scrolling message in the status window of a browser or
 * applet viewer.
 *
 * @version 1.1, June 2, 1997
 * @author Symantec
 */
public class StatusScroller implements Runnable
{
    /**
     * Constructs a StatusScroller.
     * By default, the message (set by the setString() method) will scroll
     * right-to-left, repeat, and will completely scroll off before scrolling
     * on again.
     * @see #setString
     */
    public StatusScroller()
    {
        isRightToLeft    = true;
        isRepeat        = true;
        isScrollClean    = true;
        execute            = true;
        loopFlag        = false;
        statusString    = null;
        delay            = 100;
        thread            = new Thread(this);

        //Initalize the context variable
        try
        {
            setAppletContext(symantec.itools.lang.Context.getApplet());
        }
        catch(PropertyVetoException e){}

        thread.start();
    }


    //***** Public Methods *****//

    /**
     * Sets the string to be scrolled in the browser or applet viewer.
     *
     * @param s the message to scroll
     * @see #getString
     *
     * @exception PropertyVetoException
     * if the specified property value is unacceptable
     */
    public void setString(String s) throws PropertyVetoException
    {
        if(!symantec.itools.util.GeneralUtils.objectsEqual(statusString, s))
        {
            String oldValue = statusString;

            vetos.fireVetoableChange("String", oldValue, s);

            statusString = s;
            index = 0;

            if(statusString == null || statusString.equals(""))
            {
                statusString =    null;
                workingBuffer = null;
                wblength = 0;
                sslength = 0;
                if(execute)
                    clear();
            }
            else
            {
                sslength = statusString.length();
                updateWorkingBuffer();
            }

            changes.firePropertyChange("String", oldValue, statusString);
        }
    }

    /**
     * Gets the string being scrolled.
     * @return the current scroll string
     * @see #setString
     */
    public String getString()
    {
        return statusString;
    }

    /**
     * Controls the direction the text will scroll.
     * @param b the direction to scroll the text;
     * true for right-to-left, false for left-to-right
     * @see #getRightToLeft
     *
     * @exception PropertyVetoException
     * if the specified property value is unacceptable
     */
    public void setRightToLeft(boolean b) throws PropertyVetoException
    {
        Boolean oldValue = new Boolean(isRightToLeft);
        Boolean newValue = new Boolean(b);

        vetos.fireVetoableChange("RightToLeft", oldValue, newValue);

        isRightToLeft = b;

        changes.firePropertyChange("RightToLeft", oldValue, newValue);
    }

    /**
     * Gets the direction the text will scroll.
     * @return true if the text will scroll right-to-left,
     * false if the text will scroll left-to-right
     * @see #setRightToLeft
     */
    public boolean isRightToLeft()
    {
        return isRightToLeft;
    }

    /**
     * @deprecated
     * @see #isRightToLeft
     */
    public boolean getRightToLeft()
    {
        return isRightToLeft();
    }

    /**
     * Controls whether text will scroll completely off before scrolling on
     * again.
     * @param b if true the text will scroll completely off before scrolling
     * on again, if false the text will scroll without any gap
     * @see #isScrollClean
     *
     * @exception PropertyVetoException
     * if the specified property value is unacceptable
     */
    public void setScrollClean(boolean b) throws PropertyVetoException
    {
        if(isScrollClean != b)
        {
            Boolean oldValue = new Boolean(isScrollClean);
            Boolean newValue = new Boolean(b);

            vetos.fireVetoableChange("ScrollClean", oldValue, newValue);

            isScrollClean = b;
            updateWorkingBuffer();

            changes.firePropertyChange("ScrollClean", oldValue, newValue);
        }
    }

    /**
     * Gets whether text will scroll completely off before scrolling on
     * again.
     * @return true if the text will scroll completely off before scrolling
     * on again, false if the text will scroll without any gap
     * @see #setScrollClean
     */
    public boolean isScrollClean()
    {
        return isScrollClean;
    }

    /**
     * @deprecated
     * @see #isScrollClean
     */
    public boolean getScrollClean()
    {
        return isScrollClean();
    }

    /**
     * Controls whether scrolling will automatically start when the applet is loaded.
     * @param f if true the text will start scrolling as soon as the applet
     * is loaded, if false the text will not scroll until start() is called
     * @see #isAutoStart
     * @see #start
     * @see #stop
     *
     * @exception PropertyVetoException
     * if the specified property value is unacceptable
     */
    public void setAutoStart(boolean f) throws PropertyVetoException
    {
        Boolean oldValue = new Boolean(isAutoStart());
        Boolean newValue = new Boolean(f);

        vetos.fireVetoableChange("AutoStart", oldValue, newValue);

        if(f)
            start();
        else
            stop();

        changes.firePropertyChange("AutoStart", oldValue, newValue);
    }

    /**
     * Gets whether scrolling will automatically start when the applet is loaded.
     * @return true if the text will start scrolling as soon as the applet is loaded,
     * false if the text will not scroll until start() is called
     * @see #setAutoStart
     * @see #start
     * @see #stop
     */
    public boolean isAutoStart()
    {
        return execute;
    }

    /**
     * @depicated
     * @see #isAutoStart
     */
    public boolean getAutoStart()
    {
        return isAutoStart();
    }

    /**
     * Controls whether text will repeatedly scroll or just scroll once.
     * @param f if true the text will scroll over and over,
     * if false the text will scroll off and back on, then stop
     * @see #isRepeat
     *
     * @exception PropertyVetoException
     * if the specified property value is unacceptable
     */
    public void setRepeat(boolean f) throws PropertyVetoException
    {
        Boolean oldValue = new Boolean(isRepeat);
        Boolean newValue = new Boolean(f);

        vetos.fireVetoableChange("Repeat", oldValue, newValue);

        isRepeat = f;

        changes.firePropertyChange("Repeat", oldValue, newValue);
    }

    /**
     * Gets whether text will repeatedly scroll or just scroll once.
     * @return true if the text will scroll over and over,
     * false if the text will scroll off and back on, then stop
     * @see #setRepeat
     */
    public boolean isRepeat()
    {
        return isRepeat;
    }

    /**
     * @deprecated
     * @see #isRepeat
     */
    public boolean getRepeat()
    {
        return isRepeat();
    }

    /**
     * Sets the time between the display of each character in milliseconds.
     * The minimum delay is 30 milliseconds.
     * @param d the delay, in milliseconds
     * @see #getDelay
     *
     * @exception PropertyVetoException
     * if the specified property value is unacceptable
     */
    public void setDelay(int d) throws PropertyVetoException
    {
        int temp = 0;

        if(d < 30)
            temp = 30;
        else
            temp = d;

        Integer oldValue = new Integer(delay);
        Integer newValue = new Integer(temp);

        vetos.fireVetoableChange("Delay", oldValue, newValue);

        delay = temp;

        changes.firePropertyChange("Delay", oldValue, newValue);
    }

    /**
     * Gets the time between the display of each character in milliseconds.
     * @return the delay, in milliseconds
     * @see #setDelay
     */
    public int getDelay()
    {
        return delay;
    }

    /**
     * Sets the AppletContext that has the status area for scrolling text.
     * Note: this overrides the automatically set AppletContext.
     *
     * @param c the new AppletContext
     * @see #setAppletContext(java.applet.Applet)
     *
     * @exception PropertyVetoException
     * if the specified property value is unacceptable
     */
    public void setAppletContext(AppletContext c) throws PropertyVetoException
    {
        AppletContext oldValue = context;

        vetos.fireVetoableChange("AppletContext", oldValue, c);

        context = c;

        changes.firePropertyChange("AppletContext", oldValue, c);
    }

    /**
     * Sets the AppletContext that has the status area for scrolling text.
     * This version takes an Applet object and gets the needed AppletContext from that.
     * Note: this overrides the automatically set AppletContext.
     *
     * @param a the Applet with the AppletContext to use
     * @see #setAppletContext(java.applet.AppletContext)
     *
     * @exception PropertyVetoException
     * if the specified property value is unacceptable
     */
    public void setAppletContext(Applet a) throws PropertyVetoException
    {
        if(a == null)
            setAppletContext((AppletContext)null);
        else
            setAppletContext(a.getAppletContext());
    }

    /**
     * Starts the status text scrolling.
     * @see #stop
     * @see #run
     */
    public void start()
    {
        execute = true;
        thread.resume();
    }

    /**
     * Stops the status text scrolling.
     * @see #start
     */
    public void stop()
    {
        execute   = false;
    }

    /**
     * Clears the status area.
     * Note: this does not clear the string to scroll,
     * it just clears the status area in the current AppletContext.
     */
    public void clear()
    {
        if(context != null)
        {
            //Display an empty string
            context.showStatus("");
        }
    }

    /**
     * The body of the StatusScroller Thread.
     * This method is called by the Java Virtual Machine in response to a
     * call to the start method of this object.
     */
    public void run()
    {
        String workingString = null;
        int loopIndicator;

        if(!execute) thread.suspend();
        try
        {
            while(true)
            {
                do
                {
                       //loopIndicator = index;

                    thread.sleep(delay);

                    if (execute)
                    {
                        //Get the string to display
                        workingString = scrollString();
                        if (context != null && workingString != null)
                        {
                            //Display the string
                            context.showStatus(workingString);
                        }
                    }
                }
                //Keep scrolling until an exit condition is met
                while (index != 0 || isRepeat);

                thread.suspend();
            }
        }
        catch (InterruptedException e)
        {
        }
    }

    /**
     * Adds a listener for all property change events.
     * @param listener the listener to add
     * @see #removePropertyChangeListener
     */
    public synchronized void addPropertyChangeListener(PropertyChangeListener listener)
    {
        changes.addPropertyChangeListener(listener);
    }

    /**
     * Removes a listener for all property change events.
     * @param listener the listener to remove
     * @see #addPropertyChangeListener
     */
    public synchronized void removePropertyChangeListener(PropertyChangeListener listener)
    {
        changes.removePropertyChangeListener(listener);
    }

    /**
     * Adds a listener for all vetoable property change events.
     * @param listener the listener to add
     * @see #removeVetoableChangeListener
     */
    public synchronized void addVetoableChangeListener(VetoableChangeListener listener)
    {
        vetos.addVetoableChangeListener(listener);
    }

    /**
     * Removes a listener for all vetoable property change events.
     * @param listener the listener to remove
     * @see #addVetoableChangeListener
     */
    public synchronized void removeVetoableChangeListener(VetoableChangeListener listener)
    {
        vetos.removeVetoableChangeListener(listener);
    }

       //***** Private Methods *****//

    /**
     * Handles the manipulation of the string buffer to give the
     * desired scrolling effect.
     * @return the string to be displayed
     * @see #run
     * @see #setRightToLeft
     * @see #getRightToLeft
     */
    protected String scrollString()
    {
        //If the string is null
        if(workingBuffer == null)
            return null;
        //If there is only one character
        if(wblength < 2)
            return(workingBuffer.toString());

        char ch, temp[];
        //Allocate space for the rest of the characters
        temp = new char[wblength - 1];

        if(isRightToLeft)
        {
            //Store the first character
            ch = workingBuffer.charAt(0);
            //Store the rest of the characters
            workingBuffer.getChars(1, wblength, temp, 0);
            //Shift the rest of the characters to the left one index
            workingBuffer = new StringBuffer(new String(temp));
            //Append the first character
            workingBuffer = workingBuffer.append(ch);
            //Keep track of where the original first character is
            index++;
            if(index > wblength -1)
                index = 0;
        }
        else
        {
            //Store the last character
            ch = workingBuffer.charAt(wblength - 1);
            //Store the rest of the characters
            workingBuffer.getChars(0, wblength - 1, temp, 0);
            //Place the last character at the beginning
            workingBuffer = new StringBuffer("" + ch);
            //Append the rest of the characters
            workingBuffer = workingBuffer.append(temp);
            //Keep track of where the original first character is
            index--;
            if(index < 0)
                index = wblength -1;
        }

        //Return a window onto the modified string buffer to be displayed
        return((workingBuffer.toString()).substring(0, sslength));
    }

    /**
     * Returns a String with howBig number of spaces as the content
     * @param howBig the requested number of spaces
     * @returns a String with the requested number of spaces
     */
    protected String makePadding(int howBig)
    {
        StringBuffer str = new StringBuffer(0);

        for(int i = 0; i < howBig; ++i)
            str.append(" ");
        return(str.toString());
    }

    /**
     * Updates the string buffer depending on the current settings.
     * @see #setScrollClean
     */
    protected void updateWorkingBuffer()
    {
        if(isScrollClean)
        {
            String temp = makePadding(sslength);
            workingBuffer = new StringBuffer(statusString + temp);
        }
        else
            workingBuffer = new StringBuffer(statusString);

        wblength = workingBuffer.length();
    }

    /**
     * If true, the text will scroll from the right to the left.
     * @see #setRightToLeft
     * @see #isRightToLeft
     */
    protected boolean isRightToLeft;
    /**
     * If true, the text will continue scrolling over and over.
     * @see #setRepeat
     * @see #isRepeat
     */
    protected boolean isRepeat;
    /**
     * If true, the text will scroll completely off before scrolling on again.
     * @see #setScrollClean
     * @see #isScrollClean
     */
    protected boolean isScrollClean;
    /**
     * The applet context that shows the status text.
     */
    protected AppletContext context;
    /**
     * The thread that handles scrolling the text.
     * @see #start
     * @see #stop
     */
    protected Thread thread;
    /**
     * The time between the display of each character in milliseconds.
     * @see #setDelay
     * @see #getDelay
     */
    protected int delay;
    /**
     * Working buffer length, in characters.
     */
    protected int wblength;
    /**
     * Status string length, in characters.
     */
    protected int sslength;
    /**
     * The zero-relative index of the original first character.
     */
    protected int index;
    /**
     * The string to scroll.
     */
    protected    String    statusString;
    /**
     * The string that gets scrolled.
     */
    protected StringBuffer    workingBuffer;

    private boolean execute, loopFlag;
    private symantec.itools.beans.VetoableChangeSupport vetos = new symantec.itools.beans.VetoableChangeSupport(this);
    private symantec.itools.beans.PropertyChangeSupport changes = new symantec.itools.beans.PropertyChangeSupport(this);
}