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Class Scroller


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class Scroller extends java.awt.Canvas
{
     //  Constructors

  public Scroller( );
  public Scroller( int W , int H , Font f );

     //  Methods

  public void setSize( int W , int H );
  public void setBackground( Color bg );
  public void setForeground( Color fg );
  public void setFont( Font f );
  public void setDelta( int i );
  public void Reset( );
  public int getX( );
  public int getY( );
  public void initScroll( String m , int d );
  public boolean Scroll( );
  public void drawScroll( Graphics g );
}

The Scroller class can be used to handle the fundamentals of text
scrolling. The class can do the actual drawing to the canvas if you choose,
but it does not support double buffering. You can implement the drawing
to the canvas yourself by using the getX( ) an getY( ) results, which
will tell you where the current position of the string will be.


Constructors

Scroller

public Scroller( ); This is the default constructor for the Scroller class. The width and height of the canvas will be set to 0. The font will be set to TimesRoman , Bold , 24. The FontMetrics will be set using the above Font. The Background Color will be set to Black. The Foreground Color will be set to White.

Scroller

public Scroller( int W , int H , Font f ); This is the user-defined constructor for the Scroller class. Parameters: W - the width of the canvas/applet H - the height of the canvas/applet f - the default Font to use

Methods

setSize

public void setSize( int W , int H ); This is used to set the size of the canvas/applet (for use with the default constructor) Parameters: W - the width of the canvas/applet H - the height of the canvas/applet

setBackground

public void setBackground( Color bg ); This is used to set the background color of the canvas. Parameters: bg - A Color object

setForeground

public void setForeground( Color fg ); This is used to set the color the message will be drawn in. Parameters: fg - A Color object

setFont

public void setFont( Font f ); This is used to set the font type for the message Parameters: f - a Font object

setDelta

public void setDelta( int i ); This is used to set the number of pixels the message should move between iterations of scroll. This is initially set to 5. Parameters: i - int representing the number of pixels to move

Reset

public void Reset( ); This is used to reset the state of the applet to not finished. This is used in conjunction with the Scroll method, which will check to see if it is finished scrolling the message, then return the value of it's state (finished or unfinished)

getX

public int getX( ); This will return the X coordinate for the current position of the message

getY

public int getY( ); This will return the Y coordinate for the current postion of the message

initScroll

public void initScroll( String m , int d ) This method will determine where the starting X and Y coordinates for the scroll will be based on the FontMetrics of the message passed in, and the direction passed in. Parameters: m - the message to be scrolled d - the direction which to scroll the message, from the following options 1 = left to right 2 = right to left 3 = bottom to top 4 = top to bottom

Scroll

public boolean Scroll( ); This method will update the position of the X and Y coordinates, based on the values previously passed to initScroll if the scroll is not completed, otherwise it will set the state of the scroller to finished. Returns: The state of the scroller ( finished or unfinished )

drawScroll

public void drawScroll( Graphics g ); This method will handle the drawing of the scrolling message to the canvas. It does not support doulbe-buffering. If you wish to implement double-buffering you must use the return values of Scroll( ), getX( ), and getY( ). Parameters: g - The applet or applications Graphics object.
Scroller.class
by James Savidge
e-mail: savidge@scsud.ctstateu.edu
7-14-97