* This applet is displays an attractive scrolling text window. It is very
* simple in design, but allows for a great deal of configuration. The user
* can specify multiple parameters with the <PARAM> tags,
* such as the following:
*
*
*
| fontface | *The style of Font to use. It must be a type
* supported by Java. If an invalid font face is specified,
* SansSerif will be used. SansSerif
* is also the default font face. |
*
| fontsize | *The size of Font to use. If an invalid size is
* specified, the default will be used. The default font size is
* 10. |
*
| speed | *The speed of scrolling to use. Valid values are all numbers
* from TextScroll_1_0.MIN_SPEED to
* TextScroll_1_0.MAX_SPEED, with
* TextScroll_1_0.MIN_SPEED being the slowest and
* TextScroll_1_0.MAX_SPEED being the fastest. The
* default is TextScroll_1_0.DEFAULT_SPEED. |
*
| data | *The name of the datafile to use.
* In versions 2.4 and above, you can use a complete URL in this
* parameter if you wish. If the value of this parameter starts
* with "http", it tries to create a new URL from the
* string. Otherwise, it treats it as a relative URL from the
* CODEBASE. |
*
| foreground | *The foreground color for the applet. This will be the color * of the text. The default is white. | *
| background | *The background color for the applet. The default is black. * | *
Note all of the parameters can be specified in the text file
* itself, with the exception of the name of the text file. Thus, the
* only mandatory <PARAM> tag is the data
* tag. Indeed, this is the only one I usually specify, since the data
* file changes most of the other values several times during the
* presentation.
*
*
If the user clicks on the scrolling text, the scrolling will stop. * If the user clicks again, it will start again, in the same place. * *
Developer Notes: *
* This section describes how the applet works. If you are not * interested, you can move ahead to the API. * ** * @version 2.5.1, 05 Apr 1998 * @author Kevin Swan, 013639s@dragon.acadiau.ca */ public class TextScroll_1_0 extends Applet implements Runnable { /** * The current version of this applet. */ public final String VERSION = "2.5.1"; /** * A constant representing the maximum number of milliseconds * the applet may sleep. This is the maximum number a user may * specify as the speed value, and would represent a sleep time * of MIN_SPEED milliseconds. */ public static final int MAX_SPEED = 100; /** * A constant representing the minimum number of milliseconds * the applet may sleep. This is the minimum number a user may * specify as the speed value, and would represent a sleep time * of MAX_SPEED milliseconds. */ public static final int MIN_SPEED = 1; /** * A constant representing the default number of milliseconds * the applet should sleep. This value is used for the speed * if the user specifies an invalid value, or none at all. */ public static final int DEFAULT_SPEED = 70; /** * The set of supported directives. */ public static final String[] directives = { "setForegroundColor", "setBackgroundColor", "setSpeed", "pause", "setFontFace", "setFontSize", "setCenter", "setBold", "setItalic", "setInset", "setURL" }; /** The Image to create and use for buffering. */ private Image buffImage; /** The Graphics object from the buffer Image that we can draw on. */ private Graphics buffGraphics; /** The Colors to use. */ private Color backgroundColor, foregroundColor; /** The Font to use. */ private Font font; /** The size of the Font we're using. */ private int fontSize; /** The descent of the Font we're using. */ private int descent; /** The name of the file to load. */ private String fileName; /** The height and width of the applet/clipping window. */ private int width, height; /** Whether we should center the text or not. */ private boolean center = false; /** * Holds current style setting, using constants declared in * java.awt.Font. */ private int style = Font.PLAIN; /** The number of lines of text to display. */ private int numLines; /** * The speed to scroll at. Can be from MIN_SPEED to MAX_SPEED. * Default is DEFAULT_SPEED. */ private int speed; /** * This is the target URL the applet should load if the user * clicks on the applet. */ private URL targetURL = null; /** The x coordinate to start drawing text at. */ private int inset = 3; /** boolean to flag if the Applet is currently running. */ private boolean running; /** * The vertical increment. This is how far down to print the next * line of text. */ private int verticalIncrement; /** The actual text to display, one line per entry. */ private String[] text; /** The "window" we're displaying in, used for scrolling. */ private int frame = 16; /** The current line to append when we have to add another line. */ private int currLine = 0; /** Thread to control the scrolling. */ private Thread scroller; /** * This is an undocumented element to allow greater control over * the positioning of the animation. This is how many pixels to * move the text when scrolling. The default is 1. */ private int offset = 1; /** * This variable remebers whether the mouse is inside the applet or * not. This is important because if it *is*, and we had a URL set, * then that URL is displayed in the status bar. If the mouse stays * inside the applet, and the target URL changes, that should be * reflected in the status bar. So, when setURL() is called, it must * check this flag to see if it should update the status bar. */ private boolean mouseInside = false; /** * Called during initialization. This is where we check all run-time * flags set by theBasically, the applet creates an offscreen
Image* which is uses for double-buffering. The applet writes the text * to the bottom of this area, and copies it onto the active canvas. * When the text just written is completely visible, another line * it output. A thread constantly copies the window up the onscreen *Imageand updates the applet display. Pretty basic. *
<PARAM> tags, and load the
* text. We will also prepare the text buffer.
*/
public void init () {
/* Print version info. */
System.err.println ("TextScroll_1_0 v" + TextScroll_1_0.VERSION +
"\nCopyright (C) 1998 Kevin Swan, 013639s@dragon.acadiau.ca");
running = false;
String param = null;
/*
* Get the dimensions of the applet.
*/
this.width = this.size ().width;
this.height = this.size ().height;
/*
* Get the color parameters for the text area.
*/
param = getParameter ("foreground");
if (param == null)
foregroundColor = Color.black;
else
foregroundColor = getColorFromString (param);
if (foregroundColor == null)
foregroundColor = Color.black;
param = getParameter ("background");
if (param == null)
backgroundColor = Color.white;
else
backgroundColor = getColorFromString (param);
if (backgroundColor == null)
backgroundColor = Color.white;
/*
* Get the desired Font information.
*/
param = getParameter ("fontsize");
if (param == null)
this.fontSize = 10;
else
try {
this.fontSize = Integer.parseInt (param);
} catch (NumberFormatException nfe) {
this.fontSize = 10;
}
String face = null;
param = getParameter ("fontface");
if (param == null)
face = "SansSerif";
else
face = param;
this.font = new Font (face, this.style, this.fontSize);
FontMetrics fm = this.getToolkit ().getFontMetrics (this.font);
verticalIncrement = fm.getHeight ();
this.descent = fm.getMaxDescent ();
/*
* Set the name of the file to load.
*/
param = getParameter ("data");
if (param == null)
fileName = null;
else
fileName = param;
/* Look for a different offset. */
param = getParameter ("offset");
if (param == null)
this.offset = 1;
else
try {
this.offset = Integer.parseInt (param);
} catch (NumberFormatException nfe) {
this.offset = 1;
}
/* Set the speed information. */
param = getParameter ("speed");
if (param == null)
this.speed = TextScroll_1_0.DEFAULT_SPEED;
else
try {
this.speed = Integer.parseInt (param);
} catch (NumberFormatException nfe) {
this.speed = TextScroll_1_0.DEFAULT_SPEED;
}
if (this.speed > TextScroll_1_0.MAX_SPEED || this.speed < TextScroll_1_0.MIN_SPEED)
this.speed = TextScroll_1_0.DEFAULT_SPEED;
this.resize (this.width, this.height);
/*
* buffGraphics is what we will use to draw on our buffImage, the
* offscreen canvas we will use to write the text to before clipping
* it and copying it to the active Graphics object in paint ().
*/
this.buffImage = this.createImage (this.width, this.height + 2 * verticalIncrement);
this.buffGraphics = this.buffImage.getGraphics ();
/* Prepare the offscreen buffer. */
this.buffGraphics.setColor (this.backgroundColor);
this.buffGraphics.fillRect (0, 0, this.width, this.height + 2 * verticalIncrement);
this.buffGraphics.setColor (this.foregroundColor);
this.buffGraphics.setFont (this.font);
loadData ();
} /* init () */
/**
* This method attempts to convert a String numeric
* representation of a color into an actual Color object.
* It expects the given String to be in the format
* "red,green,blue"
*
* @param rgb A comma-separated RGB numeric representation of a
* color, passed as a String.
*
* @return A Color object represented by the given RGB value,
* if the values are legal. If an error occurs, return
* null.
*/
public static Color getColorFromString (String rgb) {
int red, green, blue;
red = green = blue = 0;
if (rgb == null)
return null;
try{
red = Integer.parseInt ((rgb.substring (0, rgb.indexOf (","))).trim ());
green = Integer.parseInt ((rgb.substring(rgb.indexOf (",") + 1, rgb.lastIndexOf (","))).trim ());
blue = Integer.parseInt ((rgb.substring(rgb.lastIndexOf (",") + 1)).trim ());
} catch (NumberFormatException nfe) {
return null;
}
try {
return new Color(red, green, blue);
} catch (IllegalArgumentException iae) {
return null;
}
} /* getColorFromString () */
/**
* The implementation of the run () method, as required by
* implementing the Runnable interface. This method performs
* the actual animation.
*/
public void run () {
while (running) {
/* Move the area upwards offset pixels. */
buffGraphics.copyArea (0, 1, width, height + 2 * verticalIncrement, 0, 0 - offset);
frame -= offset;
/* The frame tells us when its time to draw another line of text. */
if (frame < (0 - descent)) {
/* Get the next line in the source file. */
String line = this.text [this.currLine];
this.currLine++;
if (this.currLine == this.numLines)
this.currLine = 0;
/*
* If the line is a method directive, try to honour it. This
* is one of the major differences between this version, for Java
* 1.0, and the standard Java 1.1 version. The standard version
* can use reflection here. We cannot use this here, so we must
* resort to a less elegant method. In this version, if we find
* a directive, we will simply farm it off to another instance
* method which will do String comparisons to try and service
* the directive.
*/
if (line.startsWith ("^^")) {
/* Strip off the leading "^^" */
line = line.substring (2, line.length ());
this.serviceDirective (line);
continue;
}
/* Treat the line as normal. */
frame = verticalIncrement;
if (!this.center)
buffGraphics.drawString (line,
this.inset,
this.height + verticalIncrement);
else {
/*
* We must center the text. We will do this in 3 steps:
* 1. Find the length of the text.
* 2. Calculate what x value to start drawing the text at.
* 3. Draw the text.
*/
FontMetrics fm = this.getToolkit ().getFontMetrics (this.font);
int length = fm.stringWidth (line);
int start = (this.width / 2) - (length / 2);
start = (start < 0) ? 0 : start;
buffGraphics.drawString (line, start, this.height + verticalIncrement);
}
}
try {
scroller.sleep (TextScroll_1_0.MAX_SPEED + 1 - this.speed);
} catch (InterruptedException ie) {
}
this.repaint ();
}
} /* run () */
/**
* This method loads the textual data that we want to display from over
* the network. It is called by init().
*/
private void loadData () {
if (fileName == null) {
this.numLines = 1;
this.text = new String[this.numLines];
this.text[0] = "No \"data\" parameter specified.";
return;
}
URL dataFile = null;
URLConnection dataConnection = null;
DataInputStream dis = null;
try {
if (!fileName.startsWith ("http"))
dataFile = new URL (getCodeBase (), fileName);
else
dataFile = new URL (fileName);
} catch (MalformedURLException mue) {
this.numLines = 1;
this.text = new String[this.numLines];
this.text[0] = "Caught MalformedURLException accessing data file.";
return;
}
try {
dataConnection = dataFile.openConnection ();
} catch (IOException ioe) {
this.numLines = 1;
this.text = new String[this.numLines];
this.text[0] = "Caught IOException opening a connection to the data file.";
return;
}
try {
dis = new DataInputStream (dataConnection.getInputStream ());
} catch (IOException ioe) {
this.numLines = 1;
this.text = new String[this.numLines];
this.text[0] = "Caught IOException opening stream on data file.";
return;
}
String line = null;
Vector data = new Vector ();
int index;
this.showStatus ("Retrieving data ...");
while (true) {
try {
line = dis.readLine ();
} catch (IOException ioe) {
/* Hope we're at EOF */
break;
}
if (line == null)
break;
data.addElement (line);
} // while
this.numLines = data.size ();
this.text = new String[this.numLines];
for (int i = 0 ; i < data.size () ; i++)
this.text[i] = new String ((String) data.elementAt (i));
try {
dis.close ();
} catch (IOException ioe) {
System.err.println ("IOException closing DataInputStream on text data.");
}
this.showStatus ("");
} /* loadData () */
/**
* Called to paint the screen.
*/
public void paint (Graphics g) {
g.drawImage (this.buffImage, 0, 0, this);
}
/**
* Called to update the screen.
*/
public void update (Graphics g) {
g.drawImage (this.buffImage, 0, 0, this);
}
/**
* Called to start this applet. If the applet has been running
* before, we will pick up where we left off.
*/
public void start () {
running = true;
(scroller = new Thread (this)).start ();
}
/**
* Stop the applet.
*/
public void stop () {
running = false;
if (scroller != null)
scroller.stop ();
}
/**
* If the Applet is running, stop it. If it is stopped, restart it.
*/
private void toggle () {
if (this.running)
this.stop ();
else
this.start ();
}
/**
* Method called when the mouse pointer enters the applet.
*
* @param e The actual event
* @param x The x coordinate the event occurred at.
* @param y The y coordinate the event occurred at.
*
* @return true if the event is handled, false otherwise.
*/
public boolean mouseEnter (Event e, int x, int y) {
this.mouseInside = true;
if (TextScroll_1_0.this.getURL () == null)
TextScroll_1_0.this.showStatus ("Click to start/stop the applet.");
else
TextScroll_1_0.this.showStatus (TextScroll_1_0.this.getURL ().toString ());
return true;
}
/**
* Method called when the mouse pointer leaves the applet.
*
* @param e The actual event
* @param x The x coordinate the event occurred at.
* @param y The y coordinate the event occurred at.
*
* @return true if the event is handled, false otherwise.
*/
public boolean mouseExit (Event e, int x, int y) {
this.mouseInside = false;
this.showStatus ("");
return true;
}
/**
* Method called when the user clicks.
*
* @param e The actual event.
* @param x The x coordinate the even occurred at.
* @param y The y coordinate the even occurred at.
*
* @return true if the event is handled, false otherwise.
*/
public boolean mouseDown (Event me, int x, int y) {
if (this.getURL () == null)
this.toggle ();
else
try {
if (this.getAppletContext () != null)
this.getAppletContext ().showDocument (this.getURL ());
} catch (Exception e) {
this.toggle ();
}
return true;
}
/**
* This method is unique to the Java 1.0 version. This is how we
* will handle directives, since we cannot take advantage of
* the reflection API.
*
* @param command The directive we are to service, without the
* "^^" characters at the front. This is simply
* a method name, followed by 0 or more whitespace,
* followed by a ( character, then a string argument, then
* a ) character.
*/
public void serviceDirective (String command) {
String methodName = command.substring (0, command.indexOf ('('));
methodName = methodName.trim ();
if (!supportedDirective (methodName)) {
System.err.println ("Unsupported directive: \"" + methodName + "\"");
return;
}
String arg = command.substring (command.indexOf ('(') + 1, command.indexOf(')'));
if (methodName.equals ("setForegroundColor"))
this.setForegroundColor (arg);
else if (methodName.equals ("setBackgroundColor"))
this.setBackgroundColor (arg);
else if (methodName.equals ("setSpeed"))
this.setSpeed (arg);
else if (methodName.equals ("pause"))
if (arg.length () > 0)
this.pause (arg);
else
this.pause ();
else if (methodName.equals ("setFontFace"))
this.setFontFace (arg);
else if (methodName.equals ("setFontSize"))
this.setFontSize (arg);
else if (methodName.equals ("setCenter"))
this.setCenter (arg);
else if (methodName.equals ("setBold"))
this.setBold (arg);
else if (methodName.equals ("setItalic"))
this.setItalic (arg);
else if (methodName.equals ("setInset"))
this.setInset (arg);
else if (methodName.equals ("setURL"))
this.setURL (arg);
else
System.err.println ("Logic Error! \"" + methodName + "\" was reported to be legal, but could not be handled!");
return;
}
/**
* This method is used to specify whether the text should be
* centered or not. The String argument must either be
* "true" or "false" The comparison is
* case-insensitive.
*
* @param boolStr A String. Must be "true" to specify
* that all further text should be centered, or
* "false" to specify normal formatting
* (left align). Any other values are ignored,
* and a quiet message is printed to stderr.
*/
public void setCenter (String boolStr) {
if (boolStr.equalsIgnoreCase ("true"))
this.center = true;
else if (boolStr.equalsIgnoreCase ("false"))
this.center = false;
else
System.err.println ("setCenter directive ignored - invalid argument: " +
boolStr);
}
/**
* This method is used to turn bold font styling on or off. It
* expects a single String argument which must be either
* "true" or "false". The comparison is
* case-insensitive.
*
* @param boolStr A String. Must be "true" to specify
* that all further text should be bold, or
* "false" to specify non-bold styling.
* Any other values are ignored, and a quiet message
* is printed to stderr.
*/
public void setBold (String boolStr) {
if (boolStr.equalsIgnoreCase ("true"))
this.style = this.style | Font.BOLD;
else if (boolStr.equalsIgnoreCase ("false"))
this.style = this.style & ~Font.BOLD;
else {
System.err.println ("setBold directive ignored - invalid argument: " +
boolStr);
return;
}
this.font = new Font (this.font.getName (), this.style, this.fontSize);
this.buffGraphics.setFont (this.font);
}
/**
* This method is used to turn italic font styling on or off. It
* expects a single String argument which must be either
* "true" or "false". The comparison is
* case-insensitive.
*
* @param boolStr A String. Must be "true" to specify
* that all further text should be italic, or
* "false" to specify non-italic styling.
* Any other values are ignored, and a quiet message
* is printed to stderr.
*/
public void setItalic (String boolStr) {
if (boolStr.equalsIgnoreCase ("true"))
this.style = this.style | Font.ITALIC;
else if (boolStr.equalsIgnoreCase ("false"))
this.style = this.style & ~Font.ITALIC;
else {
System.err.println ("setItalic directive ignored - invalid argument: " +
boolStr);
return;
}
this.font = new Font (this.font.getName (), this.style, this.fontSize);
this.buffGraphics.setFont (this.font);
}
/**
* This method is used to set the inset value. The inset is the
* x coordinate where the text will be drawn at. The default is 3.
* The argument must be a String object which can be parsed to an
* int.
*
* @param insetStr A String which can be parsed to an int.
*/
public void setInset (String insetStr) {
int val;
try {
val = Integer.parseInt (insetStr);
} catch (NumberFormatException nfe) {
System.err.println ("setInset directive ignored - invalid argument: " +
insetStr + " (Expected a number)");
return;
}
this.inset = val;
}
/**
* This method sets the currently active URL to the given URL,
* such that if the user clicks anywhere in the applet area
* after this method has been invoked, it will load the named
* URL, unless URLString is "null"
* (case insensitive), in which case clicking will simply
* result in toggling scrolling.
*
* @param URLString The URL to load in the page the applet is
* being displayed in, or "null."
*/
public void setURL (String URLString) {
if (URLString.equalsIgnoreCase ("null"))
this.setURL ((URL) null);
else
try {
this.setURL (new URL (URLString));
} catch (MalformedURLException mue) {
System.err.println ("setURL directive ignored - invalid argument: " +
URLString + "\n(Unsetting clickable link)");
this.setURL ((URL) null);
}
}
/**
* This method is used to set the target URL to an actual
* URL object. It is used by the mouse event
* handler.
*
* @param url The URL to load in the page if
* the user clicks on the applet.
*/
public void setURL (URL url) {
this.targetURL = url;
if (this.mouseInside)
if (this.targetURL == null)
this.showStatus ("Click to start/stop the applet.");
else
this.showStatus (this.targetURL.toString ());
}
/**
* Answer the currently set target URL.
*
* @return The current URL target.
*/
public URL getURL () {
return this.targetURL;
}
/**
* This method is used to determine whether or not a directive the
* user is attempting to use is supported. This is done for security
* reasons, to protect the user from accidentally calling methods
* they shouldn't be in Applet and its superclasses.
*
* @param methodName the name of the method the user is trying to use.
*
* @return true if the user is permitted to call the named method,
* false otherwise.
*/
public static boolean supportedDirective (String methodName) {
for (int i = 0 ; i < directives.length ; i++)
if (directives[i].equals (methodName))
return true;
return false;
}
/**
* Answer a little blurb about this applet.
*
* @return info about this applet.
*/
public String getAppletInfo () {
return
"TextScroll_1_0 Version " + VERSION +
" Copyright (C) 1998 by Kevin Swan, 013639s@dragon.acadiau.ca";
}
/**
* Answer information about legal parameters.
*
* @return info about the parameters.
*/
public String[][] getParameterInfo () {
String[][] pinfo = {
{ "fontface", "Serif, SansSerif, Monospaced", "The font to use" },
{ "fontsize", "integer", "The size of font to use" },
{ "speed", TextScroll_1_0.MIN_SPEED + " - " + TextScroll_1_0.MAX_SPEED, "Scroll speed" },
{ "data", "String", "Name of text file to display" },
{ "foreground", "rrr,ggg,bbb", "RGB value to use for foreground color" },
{ "background", "rrr,ggg,bbb", "RGB value to use for background color" }
};
return pinfo;
}
/**
* Sets the foreground color to the given RGB String.
*
* @param rgb a String representing a comma-seperated RGB value.
*/
public void setForegroundColor (String rgb) {
Color color = getColorFromString (rgb);
if (color != null)
foregroundColor = color;
this.buffGraphics.setColor (this.foregroundColor);
}
/**
* Sets the background color to the given RGB String.
*
* @param rgb a String representing a comma-seperated RGB value.
*/
public void setBackgroundColor (String rgb) {
Color color = getColorFromString (rgb);
if (color != null)
backgroundColor = color;
this.buffGraphics.setColor (this.backgroundColor);
this.buffGraphics.fillRect (0, 0, this.width, this.height + 2 * verticalIncrement);
this.buffGraphics.setColor (this.foregroundColor);
}
/**
* Try and pause for the given number of milliseconds. Note that the
* time is given as a String.
*
* @param time a String that should be able to be converted to an
* Integer.
*/
public void pause (String timeStr) {
Integer time;
try {
time = Integer.valueOf (timeStr);
} catch (NumberFormatException nfe) {
System.err.println ("Error: Invalid integer specified for pause (): \"" + timeStr + "\"");
return;
}
try {
this.scroller.sleep (time.intValue ());
} catch (InterruptedException ie) {
}
return;
}
/**
* This is simply a way for the user to call toggle ()
* as a directive. This was done to relieve confusion, so the user
* can simply use pause () with or without an argument
* to cause the applet to pause scrolling. If it is called with
* no arguments, this method is called, and the scrolling stops
* until the user clicks the text area.
*
*/
public void pause () {
this.toggle ();
}
/**
* Sets the speed of the applet to the given value. Note that the
* speed value should be an integer in the form of a String, between
* MIN_SPEED and MAX_SPEED. If an invalid value is specified,
* the speed value is left at its current setting.
*
* @param speedStr a String representing the integer speed to use for
* this applet.
*/
public void setSpeed (String speedStr) {
Integer speed;
try {
speed = Integer.valueOf (speedStr);
} catch (NumberFormatException nfe) {
System.err.println ("Error: Invalid integer specified for setSpeed (): \"" + speedStr + "\"");
return;
}
if ((speed.intValue () <= TextScroll_1_0.MAX_SPEED) && (speed.intValue () >= TextScroll_1_0.MIN_SPEED))
this.speed = speed.intValue ();
return;
}
/**
* This method allows the user to change fonts in the middle of
* the scrolling.
*
* @param face The String name of the new
* Font to use.
*/
public void setFontFace (String face) {
this.font = new Font (face, this.style, this.fontSize);
FontMetrics fm = this.getToolkit ().getFontMetrics (this.font);
this.verticalIncrement = fm.getHeight ();
this.descent = fm.getMaxDescent ();
this.buffGraphics.setFont (this.font);
}
/**
* This method allows the user to change font size in the middle of
* the scrolling.
*
* @param sizeStr The String representing an integer size
* of the Font to use.
*/
public void setFontSize (String sizeStr) {
int size;
try {
size = Integer.parseInt (sizeStr);
} catch (NumberFormatException nfe) {
System.err.println ("Error: Invalid integer specified for setFontSize (): \"" + sizeStr + "\"");
return;
}
this.fontSize = size;
this.font = new Font (this.font.getName(), this.style, this.fontSize);
FontMetrics fm = this.getToolkit ().getFontMetrics (this.font);
this.verticalIncrement = fm.getHeight ();
this.descent = fm.getMaxDescent ();
this.buffGraphics.setFont (this.font);
}
}