--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/de/mud/terminal/VDUBuffer.java	Thu May 22 10:41:19 2014 -0700
@@ -0,0 +1,879 @@
+/*
+ * This file is part of "JTA - Telnet/SSH for the JAVA(tm) platform".
+ *
+ * (c) Matthias L. Jugel, Marcus Mei�ner 1996-2005. All Rights Reserved.
+ *
+ * Please visit http://javatelnet.org/ for updates and contact.
+ *
+ * --LICENSE NOTICE--
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program 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 for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ * --LICENSE NOTICE--
+ *
+ */
+
+package de.mud.terminal;
+
+import java.util.Arrays;
+
+/**
+ * Implementation of a Video Display Unit (VDU) buffer. This class contains
+ * all methods to manipulate the buffer that stores characters and their
+ * attributes as well as the regions displayed.
+ *
+ * @author Matthias L. Jugel, Marcus Meißner
+ * @version $Id: VDUBuffer.java 503 2005-10-24 07:34:13Z marcus $
+ */
+public class VDUBuffer {
+
+    /** The current version id tag */
+    public final static String ID = "$Id: VDUBuffer.java 503 2005-10-24 07:34:13Z marcus $";
+
+    /** Enable debug messages. */
+    public final static int debug = 0;
+
+    public int height, width;                          /* rows and columns */
+    public boolean[] update;        /* contains the lines that need update */
+    public char[][] charArray;                  /* contains the characters */
+    public int[][] charAttributes;             /* contains character attrs */
+    public int bufSize;
+    public int maxBufSize;                                 /* buffer sizes */
+    public int screenBase;                      /* the actual screen start */
+    public int windowBase;                   /* where the start displaying */
+    public int scrollMarker;               /* marks the last line inserted */
+
+    private int topMargin;                               /* top scroll margin */
+    private int bottomMargin;                         /* bottom scroll margin */
+
+    // cursor variables
+    protected boolean showcursor = true;
+    protected int cursorX, cursorY;
+
+    /** Scroll up when inserting a line. */
+    public final static boolean SCROLL_UP = false;
+    /** Scroll down when inserting a line. */
+    public final static boolean SCROLL_DOWN = true;
+
+    /*  Attributes bit-field usage:
+     *
+     *  8421 8421 8421 8421 8421 8421 8421 8421
+     *  |||| |||| |||| |||| |||| |||| |||| |||`- Bold
+     *  |||| |||| |||| |||| |||| |||| |||| ||`-- Underline
+     *  |||| |||| |||| |||| |||| |||| |||| |`--- Invert
+     *  |||| |||| |||| |||| |||| |||| |||| `---- Low
+     *  |||| |||| |||| |||| |||| |||| |||`------ Invisible
+     *  |||| |||| |||| |||| ||`+-++++-+++------- Foreground Color
+     *  |||| |||| |`++-++++-++------------------ Background Color
+     *  |||| |||| `----------------------------- Fullwidth character
+     *  `+++-++++------------------------------- Reserved for future use
+     */
+
+    /** Make character normal. */
+    public final static int NORMAL = 0x00;
+    /** Make character bold. */
+    public final static int BOLD = 0x01;
+    /** Underline character. */
+    public final static int UNDERLINE = 0x02;
+    /** Invert character. */
+    public final static int INVERT = 0x04;
+    /** Lower intensity character. */
+    public final static int LOW = 0x08;
+    /** Invisible character. */
+    public final static int INVISIBLE = 0x10;
+    /** Unicode full-width character (CJK, et al.) */
+    public final static int FULLWIDTH = 0x8000000;
+
+    /** how much to left shift the foreground color */
+    public final static int COLOR_FG_SHIFT = 5;
+    /** how much to left shift the background color */
+    public final static int COLOR_BG_SHIFT = 14;
+    /** color mask */
+    public final static int COLOR = 0x7fffe0;    /* 0000 0000 0111 1111 1111 1111 1110 0000 */
+    /** foreground color mask */
+    public final static int COLOR_FG = 0x3fe0;   /* 0000 0000 0000 0000 0011 1111 1110 0000 */
+    /** background color mask */
+    public final static int COLOR_BG = 0x7fc000; /* 0000 0000 0111 1111 1100 0000 0000 0000 */
+
+    /**
+     * Create a new video display buffer with the passed width and height in
+     * characters.
+     * @param width the length of the character lines
+     * @param height the amount of lines on the screen
+     */
+    public VDUBuffer(int width, int height) {
+        // set the display screen size
+        setScreenSize(width, height, false);
+    }
+
+    /**
+     * Create a standard video display buffer with 80 columns and 24 lines.
+     */
+    public VDUBuffer() {
+        this(80, 24);
+    }
+
+    /**
+     * Put a character on the screen with normal font and outline.
+     * The character previously on that position will be overwritten.
+     * You need to call redraw() to update the screen.
+     * @param c x-coordinate (column)
+     * @param l y-coordinate (line)
+     * @param ch the character to show on the screen
+     * @see #insertChar
+     * @see #deleteChar
+     * @see #redraw
+     */
+    public void putChar(int c, int l, char ch) {
+        putChar(c, l, ch, NORMAL);
+    }
+
+    /**
+     * Put a character on the screen with specific font and outline.
+     * The character previously on that position will be overwritten.
+     * You need to call redraw() to update the screen.
+     * @param c x-coordinate (column)
+     * @param l y-coordinate (line)
+     * @param ch the character to show on the screen
+     * @param attributes the character attributes
+     * @see #BOLD
+     * @see #UNDERLINE
+     * @see #INVERT
+     * @see #INVISIBLE
+     * @see #NORMAL
+     * @see #LOW
+     * @see #insertChar
+     * @see #deleteChar
+     * @see #redraw
+     */
+
+    public void putChar(int c, int l, char ch, int attributes) {
+        charArray[screenBase + l][c] = ch;
+        charAttributes[screenBase + l][c] = attributes;
+
+        if (l < height)
+            update[l + 1] = true;
+    }
+
+    /**
+     * Get the character at the specified position.
+     * @param c x-coordinate (column)
+     * @param l y-coordinate (line)
+     * @see #putChar
+     */
+    public char getChar(int c, int l) {
+        return charArray[screenBase + l][c];
+    }
+
+    /**
+     * Get the attributes for the specified position.
+     * @param c x-coordinate (column)
+     * @param l y-coordinate (line)
+     * @see #putChar
+     */
+    public int getAttributes(int c, int l) {
+        return charAttributes[screenBase + l][c];
+    }
+
+    /**
+     * Insert a character at a specific position on the screen.
+     * All character right to from this position will be moved one to the right.
+     * You need to call redraw() to update the screen.
+     * @param c x-coordinate (column)
+     * @param l y-coordinate (line)
+     * @param ch the character to insert
+     * @param attributes the character attributes
+     * @see #BOLD
+     * @see #UNDERLINE
+     * @see #INVERT
+     * @see #INVISIBLE
+     * @see #NORMAL
+     * @see #LOW
+     * @see #putChar
+     * @see #deleteChar
+     * @see #redraw
+     */
+    public void insertChar(int c, int l, char ch, int attributes) {
+        System.arraycopy(charArray[screenBase + l], c,
+                         charArray[screenBase + l], c + 1, width - c - 1);
+        System.arraycopy(charAttributes[screenBase + l], c,
+                         charAttributes[screenBase + l], c + 1, width - c - 1);
+        putChar(c, l, ch, attributes);
+    }
+
+    /**
+     * Delete a character at a given position on the screen.
+     * All characters right to the position will be moved one to the left.
+     * You need to call redraw() to update the screen.
+     * @param c x-coordinate (column)
+     * @param l y-coordinate (line)
+     * @see #putChar
+     * @see #insertChar
+     * @see #redraw
+     */
+    public void deleteChar(int c, int l) {
+        if (c < width - 1) {
+            System.arraycopy(charArray[screenBase + l], c + 1,
+                             charArray[screenBase + l], c, width - c - 1);
+            System.arraycopy(charAttributes[screenBase + l], c + 1,
+                             charAttributes[screenBase + l], c, width - c - 1);
+        }
+
+        putChar(width - 1, l, (char) 0);
+    }
+
+    /**
+     * Put a String at a specific position. Any characters previously on that
+     * position will be overwritten. You need to call redraw() for screen update.
+     * @param c x-coordinate (column)
+     * @param l y-coordinate (line)
+     * @param s the string to be shown on the screen
+     * @see #BOLD
+     * @see #UNDERLINE
+     * @see #INVERT
+     * @see #INVISIBLE
+     * @see #NORMAL
+     * @see #LOW
+     * @see #putChar
+     * @see #insertLine
+     * @see #deleteLine
+     * @see #redraw
+     */
+    public void putString(int c, int l, String s) {
+        putString(c, l, s, NORMAL);
+    }
+
+    /**
+     * Put a String at a specific position giving all characters the same
+     * attributes. Any characters previously on that position will be
+     * overwritten. You need to call redraw() to update the screen.
+     * @param c x-coordinate (column)
+     * @param l y-coordinate (line)
+     * @param s the string to be shown on the screen
+     * @param attributes character attributes
+     * @see #BOLD
+     * @see #UNDERLINE
+     * @see #INVERT
+     * @see #INVISIBLE
+     * @see #NORMAL
+     * @see #LOW
+     * @see #putChar
+     * @see #insertLine
+     * @see #deleteLine
+     * @see #redraw
+     */
+    public void putString(int c, int l, String s, int attributes) {
+        for (int i = 0; i < s.length() && c + i < width; i++)
+            putChar(c + i, l, s.charAt(i), attributes);
+    }
+
+    /**
+     * Insert a blank line at a specific position.
+     * The current line and all previous lines are scrolled one line up. The
+     * top line is lost. You need to call redraw() to update the screen.
+     * @param l the y-coordinate to insert the line
+     * @see #deleteLine
+     * @see #redraw
+     */
+    public void insertLine(int l) {
+        insertLine(l, 1, SCROLL_UP);
+    }
+
+    /**
+     * Insert blank lines at a specific position.
+     * You need to call redraw() to update the screen
+     * @param l the y-coordinate to insert the line
+     * @param n amount of lines to be inserted
+     * @see #deleteLine
+     * @see #redraw
+     */
+    public void insertLine(int l, int n) {
+        insertLine(l, n, SCROLL_UP);
+    }
+
+    /**
+     * Insert a blank line at a specific position. Scroll text according to
+     * the argument.
+     * You need to call redraw() to update the screen
+     * @param l the y-coordinate to insert the line
+     * @param scrollDown scroll down
+     * @see #deleteLine
+     * @see #SCROLL_UP
+     * @see #SCROLL_DOWN
+     * @see #redraw
+     */
+    public void insertLine(int l, boolean scrollDown) {
+        insertLine(l, 1, scrollDown);
+    }
+
+    /**
+     * Insert blank lines at a specific position.
+     * The current line and all previous lines are scrolled one line up. The
+     * top line is lost. You need to call redraw() to update the screen.
+     * @param l the y-coordinate to insert the line
+     * @param n number of lines to be inserted
+     * @param scrollDown scroll down
+     * @see #deleteLine
+     * @see #SCROLL_UP
+     * @see #SCROLL_DOWN
+     * @see #redraw
+     */
+
+    public synchronized void insertLine(int l, int n, boolean scrollDown) {
+        char cbuf[][] = null;
+        int abuf[][] = null;
+        int offset = 0;
+        int oldBase = screenBase;
+        int newScreenBase = screenBase;
+        int newWindowBase = windowBase;
+        int newBufSize = bufSize;
+
+        if (l > bottomMargin) /* We do not scroll below bottom margin (below the scrolling region). */
+            return;
+
+        int top = (l < topMargin ?
+                   0 : (l > bottomMargin ?
+                        (bottomMargin + 1 < height ?
+                         bottomMargin + 1 : height - 1) : topMargin));
+        int bottom = (l > bottomMargin ?
+                      height - 1 : (l < topMargin ?
+                                    (topMargin > 0 ?
+                                     topMargin - 1 : 0) : bottomMargin));
+
+        // System.out.println("l is "+l+", top is "+top+", bottom is "+bottom+", bottomargin is "+bottomMargin+", topMargin is "+topMargin);
+        if (scrollDown) {
+            if (n > (bottom - top)) n = (bottom - top);
+
+            int size = bottom - l - (n - 1);
+
+            if (size < 0) size = 0;
+
+            cbuf = new char[size][];
+            abuf = new int[size][];
+            System.arraycopy(charArray, oldBase + l, cbuf, 0, bottom - l - (n - 1));
+            System.arraycopy(charAttributes, oldBase + l,
+                             abuf, 0, bottom - l - (n - 1));
+            System.arraycopy(cbuf, 0, charArray, oldBase + l + n,
+                             bottom - l - (n - 1));
+            System.arraycopy(abuf, 0, charAttributes, oldBase + l + n,
+                             bottom - l - (n - 1));
+            cbuf = charArray;
+            abuf = charAttributes;
+        }
+        else {
+            try {
+                if (n > (bottom - top) + 1) n = (bottom - top) + 1;
+
+                if (bufSize < maxBufSize) {
+                    if (bufSize + n > maxBufSize) {
+                        offset = n - (maxBufSize - bufSize);
+                        scrollMarker += offset;
+                        newBufSize = maxBufSize;
+                        newScreenBase = maxBufSize - height - 1;
+                        newWindowBase = screenBase;
+                    }
+                    else {
+                        scrollMarker += n;
+                        newScreenBase += n;
+                        newWindowBase += n;
+                        newBufSize += n;
+                    }
+
+                    cbuf = new char[newBufSize][];
+                    abuf = new int[newBufSize][];
+                }
+                else {
+                    offset = n;
+                    cbuf = charArray;
+                    abuf = charAttributes;
+                }
+
+                // copy anything from the top of the buffer (+offset) to the new top
+                // up to the screenBase.
+                if (oldBase > 0) {
+                    System.arraycopy(charArray, offset,
+                                     cbuf, 0,
+                                     oldBase - offset);
+                    System.arraycopy(charAttributes, offset,
+                                     abuf, 0,
+                                     oldBase - offset);
+                }
+
+                // copy anything from the top of the screen (screenBase) up to the
+                // topMargin to the new screen
+                if (top > 0) {
+                    System.arraycopy(charArray, oldBase,
+                                     cbuf, newScreenBase,
+                                     top);
+                    System.arraycopy(charAttributes, oldBase,
+                                     abuf, newScreenBase,
+                                     top);
+                }
+
+                // copy anything from the topMargin up to the amount of lines inserted
+                // to the gap left over between scrollback buffer and screenBase
+                if (oldBase >= 0) {
+                    System.arraycopy(charArray, oldBase + top,
+                                     cbuf, oldBase - offset,
+                                     n);
+                    System.arraycopy(charAttributes, oldBase + top,
+                                     abuf, oldBase - offset,
+                                     n);
+                }
+
+                // copy anything from topMargin + n up to the line linserted to the
+                // topMargin
+                System.arraycopy(charArray, oldBase + top + n,
+                                 cbuf, newScreenBase + top,
+                                 l - top - (n - 1));
+                System.arraycopy(charAttributes, oldBase + top + n,
+                                 abuf, newScreenBase + top,
+                                 l - top - (n - 1));
+
+                //
+                // copy the all lines next to the inserted to the new buffer
+                if (l < height - 1) {
+                    System.arraycopy(charArray, oldBase + l + 1,
+                                     cbuf, newScreenBase + l + 1,
+                                     (height - 1) - l);
+                    System.arraycopy(charAttributes, oldBase + l + 1,
+                                     abuf, newScreenBase + l + 1,
+                                     (height - 1) - l);
+                }
+            }
+            catch (ArrayIndexOutOfBoundsException e) {
+                // this should not happen anymore, but I will leave the code
+                // here in case something happens anyway. That code above is
+                // so complex I always have a hard time understanding what
+                // I did, even though there are comments
+                System.err.println("*** Error while scrolling up:");
+                System.err.println("--- BEGIN STACK TRACE ---");
+                e.printStackTrace();
+                System.err.println("--- END STACK TRACE ---");
+                System.err.println("bufSize=" + bufSize + ", maxBufSize=" + maxBufSize);
+                System.err.println("top=" + top + ", bottom=" + bottom);
+                System.err.println("n=" + n + ", l=" + l);
+                System.err.println("screenBase=" + screenBase + ", windowBase=" + windowBase);
+                System.err.println("newScreenBase=" + newScreenBase + ", newWindowBase=" + newWindowBase);
+                System.err.println("oldBase=" + oldBase);
+                System.err.println("size.width=" + width + ", size.height=" + height);
+                System.err.println("abuf.length=" + abuf.length + ", cbuf.length=" + cbuf.length);
+                System.err.println("*** done dumping debug information");
+            }
+        }
+
+        // this is a little helper to mark the scrolling
+        scrollMarker -= n;
+
+        for (int i = 0; i < n; i++) {
+            cbuf[(newScreenBase + l) + (scrollDown ? i : -i)] = new char[width];
+            Arrays.fill(cbuf[(newScreenBase + l) + (scrollDown ? i : -i)], ' ');
+            abuf[(newScreenBase + l) + (scrollDown ? i : -i)] = new int[width];
+        }
+
+        charArray = cbuf;
+        charAttributes = abuf;
+        screenBase = newScreenBase;
+        windowBase = newWindowBase;
+        bufSize = newBufSize;
+
+        if (scrollDown)
+            markLine(l, bottom - l + 1);
+        else
+            markLine(top, l - top + 1);
+
+        display.updateScrollBar();
+    }
+
+    /**
+     * Delete a line at a specific position. Subsequent lines will be scrolled
+     * up to fill the space and a blank line is inserted at the end of the
+     * screen.
+     * @param l the y-coordinate to insert the line
+     * @see #deleteLine
+     */
+    public void deleteLine(int l) {
+        int bottom = (l > bottomMargin ? height - 1 :
+                      (l < topMargin ? topMargin : bottomMargin + 1));
+        int numRows = bottom - l - 1;
+        char[] discardedChars = charArray[screenBase + l];
+        int[] discardedAttributes = charAttributes[screenBase + l];
+
+        if (numRows > 0) {
+            System.arraycopy(charArray, screenBase + l + 1,
+                             charArray, screenBase + l, numRows);
+            System.arraycopy(charAttributes, screenBase + l + 1,
+                             charAttributes, screenBase + l, numRows);
+        }
+
+        int newBottomRow = screenBase + bottom - 1;
+        charArray[newBottomRow] = discardedChars;
+        charAttributes[newBottomRow] = discardedAttributes;
+        Arrays.fill(charArray[newBottomRow], ' ');
+        Arrays.fill(charAttributes[newBottomRow], 0);
+        markLine(l, bottom - l);
+    }
+
+    /**
+     * Delete a rectangular portion of the screen.
+     * You need to call redraw() to update the screen.
+     * @param c x-coordinate (column)
+     * @param l y-coordinate (row)
+     * @param w with of the area in characters
+     * @param h height of the area in characters
+     * @param curAttr attribute to fill
+     * @see #deleteChar
+     * @see #deleteLine
+     * @see #redraw
+     */
+    public void deleteArea(int c, int l, int w, int h, int curAttr) {
+        int endColumn = c + w;
+        int targetRow = screenBase + l;
+
+        for (int i = 0; i < h && l + i < height; i++) {
+            Arrays.fill(charAttributes[targetRow], c, endColumn, curAttr);
+            Arrays.fill(charArray[targetRow], c, endColumn, ' ');
+            targetRow++;
+        }
+
+        markLine(l, h);
+    }
+
+    /**
+     * Delete a rectangular portion of the screen.
+     * You need to call redraw() to update the screen.
+     * @param c x-coordinate (column)
+     * @param l y-coordinate (row)
+     * @param w with of the area in characters
+     * @param h height of the area in characters
+     * @see #deleteChar
+     * @see #deleteLine
+     * @see #redraw
+     */
+    public void deleteArea(int c, int l, int w, int h) {
+        deleteArea(c, l, w, h, 0);
+    }
+
+    /**
+     * Sets whether the cursor is visible or not.
+     * @param doshow
+     */
+    public void showCursor(boolean doshow) {
+        showcursor = doshow;
+    }
+
+    /**
+     * Check whether the cursor is currently visible.
+     * @return visibility
+     */
+    public boolean isCursorVisible() {
+        return showcursor;
+    }
+
+    /**
+     * Puts the cursor at the specified position.
+     * @param c column
+     * @param l line
+     */
+    public void setCursorPosition(int c, int l) {
+        cursorX = c;
+        cursorY = l;
+    }
+
+    /**
+     * Get the current column of the cursor position.
+     */
+    public int getCursorColumn() {
+        return cursorX;
+    }
+
+    /**
+     * Get the current line of the cursor position.
+     */
+    public int getCursorRow() {
+        return cursorY;
+    }
+
+    /**
+     * Set the current window base. This allows to view the scrollback buffer.
+     * @param line the line where the screen window starts
+     * @see #setBufferSize
+     * @see #getBufferSize
+     */
+    public void setWindowBase(int line) {
+        if (line > screenBase)
+            line = screenBase;
+        else if (line < 0) line = 0;
+
+        windowBase = line;
+        update[0] = true;
+        redraw();
+    }
+
+    /**
+     * Get the current window base.
+     * @see #setWindowBase
+     */
+    public int getWindowBase() {
+        return windowBase;
+    }
+
+    /**
+     * Set the scroll margins simultaneously.  If they're out of bounds, trim them.
+     * @param l1 line that is the top
+     * @param l2 line that is the bottom
+     */
+    public void setMargins(int l1, int l2) {
+        if (l1 > l2)
+            return;
+
+        if (l1 < 0)
+            l1 = 0;
+
+        if (l2 >= height)
+            l2 = height - 1;
+
+        topMargin = l1;
+        bottomMargin = l2;
+    }
+
+    /**
+     * Set the top scroll margin for the screen. If the current bottom margin
+     * is smaller it will become the top margin and the line will become the
+     * bottom margin.
+     * @param l line that is the margin
+     */
+    public void setTopMargin(int l) {
+        if (l > bottomMargin) {
+            topMargin = bottomMargin;
+            bottomMargin = l;
+        }
+        else
+            topMargin = l;
+
+        if (topMargin < 0) topMargin = 0;
+
+        if (bottomMargin >= height) bottomMargin = height - 1;
+    }
+
+    /**
+     * Get the top scroll margin.
+     */
+    public int getTopMargin() {
+        return topMargin;
+    }
+
+    /**
+     * Set the bottom scroll margin for the screen. If the current top margin
+     * is bigger it will become the bottom margin and the line will become the
+     * top margin.
+     * @param l line that is the margin
+     */
+    public void setBottomMargin(int l) {
+        if (l < topMargin) {
+            bottomMargin = topMargin;
+            topMargin = l;
+        }
+        else
+            bottomMargin = l;
+
+        if (topMargin < 0) topMargin = 0;
+
+        if (bottomMargin >= height) bottomMargin = height - 1;
+    }
+
+    /**
+     * Get the bottom scroll margin.
+     */
+    public int getBottomMargin() {
+        return bottomMargin;
+    }
+
+    /**
+     * Set scrollback buffer size.
+     * @param amount new size of the buffer
+     */
+    public void setBufferSize(int amount) {
+        if (amount < height) amount = height;
+
+        if (amount < maxBufSize) {
+            char cbuf[][] = new char[amount][width];
+            int abuf[][] = new int[amount][width];
+            int copyStart = bufSize - amount < 0 ? 0 : bufSize - amount;
+            int copyCount = bufSize - amount < 0 ? bufSize : amount;
+
+            if (charArray != null)
+                System.arraycopy(charArray, copyStart, cbuf, 0, copyCount);
+
+            if (charAttributes != null)
+                System.arraycopy(charAttributes, copyStart, abuf, 0, copyCount);
+
+            charArray = cbuf;
+            charAttributes = abuf;
+            bufSize = copyCount;
+            screenBase = bufSize - height;
+            windowBase = screenBase;
+        }
+
+        maxBufSize = amount;
+        update[0] = true;
+        redraw();
+    }
+
+    /**
+     * Retrieve current scrollback buffer size.
+     * @see #setBufferSize
+     */
+    public int getBufferSize() {
+        return bufSize;
+    }
+
+    /**
+     * Retrieve maximum buffer Size.
+     * @see #getBufferSize
+     */
+    public int getMaxBufferSize() {
+        return maxBufSize;
+    }
+
+    /**
+     * Change the size of the screen. This will include adjustment of the
+     * scrollback buffer.
+     * @param w of the screen
+     * @param h of the screen
+     */
+    public void setScreenSize(int w, int h, boolean broadcast) {
+        char cbuf[][];
+        int abuf[][];
+        int maxSize = bufSize;
+
+        if (w < 1 || h < 1) return;
+
+        if (debug > 0)
+            System.err.println("VDU: screen size [" + w + "," + h + "]");
+
+        if (h > maxBufSize)
+            maxBufSize = h;
+
+        if (h > bufSize) {
+            bufSize = h;
+            screenBase = 0;
+            windowBase = 0;
+        }
+
+        if (windowBase + h >= bufSize)
+            windowBase = bufSize - h;
+
+        if (screenBase + h >= bufSize)
+            screenBase = bufSize - h;
+
+        cbuf = new char[bufSize][w];
+        abuf = new int[bufSize][w];
+
+        for (int i = 0; i < bufSize; i++) {
+            Arrays.fill(cbuf[i], ' ');
+        }
+
+        if (bufSize < maxSize)
+            maxSize = bufSize;
+
+        int rowLength;
+
+        if (charArray != null && charAttributes != null) {
+            for (int i = 0; i < maxSize && charArray[i] != null; i++) {
+                rowLength = charArray[i].length;
+                System.arraycopy(charArray[i], 0, cbuf[i], 0,
+                                 w < rowLength ? w : rowLength);
+                System.arraycopy(charAttributes[i], 0, abuf[i], 0,
+                                 w < rowLength ? w : rowLength);
+            }
+        }
+
+        int C = getCursorColumn();
+
+        if (C < 0)
+            C = 0;
+        else if (C >= width)
+            C = width - 1;
+
+        int R = getCursorRow();
+
+        if (R < 0)
+            R = 0;
+        else if (R >= height)
+            R = height - 1;
+
+        setCursorPosition(C, R);
+        charArray = cbuf;
+        charAttributes = abuf;
+        width = w;
+        height = h;
+        topMargin = 0;
+        bottomMargin = h - 1;
+        update = new boolean[h + 1];
+        update[0] = true;
+        /*  FIXME: ???
+        if(resizeStrategy == RESIZE_FONT)
+          setBounds(getBounds());
+        */
+    }
+
+    /**
+     * Get amount of rows on the screen.
+     */
+    public int getRows() {
+        return height;
+    }
+
+    /**
+     * Get amount of columns on the screen.
+     */
+    public int getColumns() {
+        return width;
+    }
+
+    /**
+     * Mark lines to be updated with redraw().
+     * @param l starting line
+     * @param n amount of lines to be updated
+     * @see #redraw
+     */
+    public void markLine(int l, int n) {
+        for (int i = 0; (i < n) && (l + i < height); i++)
+            update[l + i + 1] = true;
+    }
+
+//  private static int checkBounds(int value, int lower, int upper) {
+//    if (value < lower)
+//      return lower;
+//    else if (value > upper)
+//      return upper;
+//    else
+//      return value;
+//  }
+
+    /** a generic display that should redraw on demand */
+    protected VDUDisplay display;
+
+    public void setDisplay(VDUDisplay display) {
+        this.display = display;
+    }
+
+    /**
+     * Trigger a redraw on the display.
+     */
+    protected void redraw() {
+        if (display != null)
+            display.redraw();
+    }
+}