https://openjdk.java.net/ 
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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package javax.swing;

import javax.swing.table.*;
import java.awt.*;
import java.awt.print.*;
import java.awt.geom.*;
import java.text.MessageFormat;


An implementation of Printable for printing
JTables.


This implementation spreads table rows naturally in sequence
across multiple pages, fitting as many rows as possible per page.
The distribution of columns, on the other hand, is controlled by a
printing mode parameter passed to the constructor. When
JTable.PrintMode.NORMAL is used, the implementation
handles columns in a similar manner to how it handles rows, spreading them
across multiple pages (in an order consistent with the table's
ComponentOrientation).
When JTable.PrintMode.FIT_WIDTH is given, the implementation
scales the output smaller if necessary, to ensure that all columns fit on
the page. (Note that width and height are scaled equally, ensuring that the
aspect ratio remains the same).


The portion of table printed on each page is headed by the
appropriate section of the table's JTableHeader.


Header and footer text can be added to the output by providing
MessageFormat instances to the constructor. The
printing code requests Strings from the formats by calling
their format method with a single parameter:
an Object array containing a single element of type
Integer, representing the current page number.


There are certain circumstances where this Printable
cannot fit items appropriately, resulting in clipped output.
These are:

    
  
  • In any mode, when the header or footer text is too wide to
      fit completely in the printable area. The implementation
      prints as much of the text as possible starting from the beginning,
      as determined by the table's ComponentOrientation.
  
  • In any mode, when a row is too tall to fit in the
      printable area. The upper most portion of the row
      is printed and no lower border is shown.
  
  • In JTable.PrintMode.NORMAL when a column
      is too wide to fit in the printable area. The center of the
      column is printed and no left and right borders are shown.




It is entirely valid for a developer to wrap this Printable
inside another in order to create complex reports and documents. They may
even request that different pages be rendered into different sized
printable areas. The implementation was designed to handle this by
performing most of its calculations on the fly. However, providing different
sizes works best when JTable.PrintMode.FIT_WIDTH is used, or
when only the printable width is changed between pages. This is because when
it is printing a set of rows in JTable.PrintMode.NORMAL and the
implementation determines a need to distribute columns across pages,
it assumes that all of those rows will fit on each subsequent page needed
to fit the columns.


It is the responsibility of the developer to ensure that the table is not
modified in any way after this Printable is created (invalid
modifications include changes in: size, renderers, or underlying data).
The behavior of this Printable is undefined if the table is
changed at any time after creation.

Author: Shannon Hickey
/**
 * An implementation of <code>Printable</code> for printing
 * <code>JTable</code>s.
 * <p>
 * This implementation spreads table rows naturally in sequence
 * across multiple pages, fitting as many rows as possible per page.
 * The distribution of columns, on the other hand, is controlled by a
 * printing mode parameter passed to the constructor. When
 * <code>JTable.PrintMode.NORMAL</code> is used, the implementation
 * handles columns in a similar manner to how it handles rows, spreading them
 * across multiple pages (in an order consistent with the table's
 * <code>ComponentOrientation</code>).
 * When <code>JTable.PrintMode.FIT_WIDTH</code> is given, the implementation
 * scales the output smaller if necessary, to ensure that all columns fit on
 * the page. (Note that width and height are scaled equally, ensuring that the
 * aspect ratio remains the same).
 * <p>
 * The portion of table printed on each page is headed by the
 * appropriate section of the table's <code>JTableHeader</code>.
 * <p>
 * Header and footer text can be added to the output by providing
 * <code>MessageFormat</code> instances to the constructor. The
 * printing code requests Strings from the formats by calling
 * their <code>format</code> method with a single parameter:
 * an <code>Object</code> array containing a single element of type
 * <code>Integer</code>, representing the current page number.
 * <p>
 * There are certain circumstances where this <code>Printable</code>
 * cannot fit items appropriately, resulting in clipped output.
 * These are:
 * <ul>
 *   <li>In any mode, when the header or footer text is too wide to
 *       fit completely in the printable area. The implementation
 *       prints as much of the text as possible starting from the beginning,
 *       as determined by the table's <code>ComponentOrientation</code>.
 *   <li>In any mode, when a row is too tall to fit in the
 *       printable area. The upper most portion of the row
 *       is printed and no lower border is shown.
 *   <li>In <code>JTable.PrintMode.NORMAL</code> when a column
 *       is too wide to fit in the printable area. The center of the
 *       column is printed and no left and right borders are shown.
 * </ul>
 * <p>
 * It is entirely valid for a developer to wrap this <code>Printable</code>
 * inside another in order to create complex reports and documents. They may
 * even request that different pages be rendered into different sized
 * printable areas. The implementation was designed to handle this by
 * performing most of its calculations on the fly. However, providing different
 * sizes works best when <code>JTable.PrintMode.FIT_WIDTH</code> is used, or
 * when only the printable width is changed between pages. This is because when
 * it is printing a set of rows in <code>JTable.PrintMode.NORMAL</code> and the
 * implementation determines a need to distribute columns across pages,
 * it assumes that all of those rows will fit on each subsequent page needed
 * to fit the columns.
 * <p>
 * It is the responsibility of the developer to ensure that the table is not
 * modified in any way after this <code>Printable</code> is created (invalid
 * modifications include changes in: size, renderers, or underlying data).
 * The behavior of this <code>Printable</code> is undefined if the table is
 * changed at any time after creation.
 *
 * @author  Shannon Hickey
 */
class TablePrintable implements Printable {

    
The table to print. 
/** The table to print. */
    private JTable table;

    
For quick reference to the table's header. 
/** For quick reference to the table's header. */
    private JTableHeader header;

    
For quick reference to the table's column model. 
/** For quick reference to the table's column model. */
    private TableColumnModel colModel;

    
To save multiple calculations of total column width. 
/** To save multiple calculations of total column width. */
    private int totalColWidth;

    
The printing mode of this printable. 
/** The printing mode of this printable. */
    private JTable.PrintMode printMode;

    
Provides the header text for the table. 
/** Provides the header text for the table. */
    private MessageFormat headerFormat;

    
Provides the footer text for the table. 
/** Provides the footer text for the table. */
    private MessageFormat footerFormat;

    
The most recent page index asked to print. 
/** The most recent page index asked to print. */
    private int last = -1;

    
The next row to print. 
/** The next row to print. */
    private int row = 0;

    
The next column to print. 
/** The next column to print. */
    private int col = 0;

    
Used to store an area of the table to be printed. 
/** Used to store an area of the table to be printed. */
    private final Rectangle clip = new Rectangle(0, 0, 0, 0);

    
Used to store an area of the table's header to be printed. 
/** Used to store an area of the table's header to be printed. */
    private final Rectangle hclip = new Rectangle(0, 0, 0, 0);

    
Saves the creation of multiple rectangles. 
/** Saves the creation of multiple rectangles. */
    private final Rectangle tempRect = new Rectangle(0, 0, 0, 0);

    
Vertical space to leave between table and header/footer text. 
/** Vertical space to leave between table and header/footer text. */
    private static final int H_F_SPACE = 8;

    
Font size for the header text. 
/** Font size for the header text. */
    private static final float HEADER_FONT_SIZE = 18.0f;

    
Font size for the footer text. 
/** Font size for the footer text. */
    private static final float FOOTER_FONT_SIZE = 12.0f;

    
The font to use in rendering header text. 
/** The font to use in rendering header text. */
    private Font headerFont;

    
The font to use in rendering footer text. 
/** The font to use in rendering footer text. */
    private Font footerFont;

    
Create a new TablePrintable for the given
JTable. Header and footer text can be specified using the
two MessageFormat parameters. When called upon to provide
a String, each format is given the current page number.

Params:
  • table –         the table to print
  • printMode –     the printing mode for this printable
  • headerFormat –  a MessageFormat specifying the text to
                      be used in printing a header, or null for none
  • footerFormat –  a MessageFormat specifying the text to
                      be used in printing a footer, or null for none
Throws:
/**
     * Create a new <code>TablePrintable</code> for the given
     * <code>JTable</code>. Header and footer text can be specified using the
     * two <code>MessageFormat</code> parameters. When called upon to provide
     * a String, each format is given the current page number.
     *
     * @param  table         the table to print
     * @param  printMode     the printing mode for this printable
     * @param  headerFormat  a <code>MessageFormat</code> specifying the text to
     *                       be used in printing a header, or null for none
     * @param  footerFormat  a <code>MessageFormat</code> specifying the text to
     *                       be used in printing a footer, or null for none
     * @throws IllegalArgumentException if passed an invalid print mode
     */
    public TablePrintable(JTable table,
                          JTable.PrintMode printMode,
                          MessageFormat headerFormat,
                          MessageFormat footerFormat) {

        this.table = table;

        header = table.getTableHeader();
        colModel = table.getColumnModel();
        totalColWidth = colModel.getTotalColumnWidth();

        if (header != null) {
            // the header clip height can be set once since it's unchanging
            hclip.height = header.getHeight();
        }

        this.printMode = printMode;

        this.headerFormat = headerFormat;
        this.footerFormat = footerFormat;

        // derive the header and footer font from the table's font
        headerFont = table.getFont().deriveFont(Font.BOLD,
                                                HEADER_FONT_SIZE);
        footerFont = table.getFont().deriveFont(Font.PLAIN,
                                                FOOTER_FONT_SIZE);
    }

    
Prints the specified page of the table into the given Graphics context, in the specified format. 
Params:
  • graphics –    the context into which the page is drawn
  • pageFormat –  the size and orientation of the page being drawn
  • pageIndex –   the zero based index of the page to be drawn
Throws:
Returns: PAGE_EXISTS if the page is rendered successfully, or
         NO_SUCH_PAGE if a non-existent page index is specified
/**
     * Prints the specified page of the table into the given {@link Graphics}
     * context, in the specified format.
     *
     * @param   graphics    the context into which the page is drawn
     * @param   pageFormat  the size and orientation of the page being drawn
     * @param   pageIndex   the zero based index of the page to be drawn
     * @return  PAGE_EXISTS if the page is rendered successfully, or
     *          NO_SUCH_PAGE if a non-existent page index is specified
     * @throws  PrinterException if an error causes printing to be aborted
     */
    public int print(Graphics graphics, PageFormat pageFormat, int pageIndex)
                                                       throws PrinterException {

        // for easy access to these values
        final int imgWidth = (int)pageFormat.getImageableWidth();
        final int imgHeight = (int)pageFormat.getImageableHeight();

        if (imgWidth <= 0) {
            throw new PrinterException("Width of printable area is too small.");
        }

        // to pass the page number when formatting the header and footer text
        Object[] pageNumber = new Object[]{Integer.valueOf(pageIndex + 1)};

        // fetch the formatted header text, if any
        String headerText = null;
        if (headerFormat != null) {
            headerText = headerFormat.format(pageNumber);
        }

        // fetch the formatted footer text, if any
        String footerText = null;
        if (footerFormat != null) {
            footerText = footerFormat.format(pageNumber);
        }

        // to store the bounds of the header and footer text
        Rectangle2D hRect = null;
        Rectangle2D fRect = null;

        // the amount of vertical space needed for the header and footer text
        int headerTextSpace = 0;
        int footerTextSpace = 0;

        // the amount of vertical space available for printing the table
        int availableSpace = imgHeight;

        // if there's header text, find out how much space is needed for it
        // and subtract that from the available space
        if (headerText != null) {
            graphics.setFont(headerFont);
            hRect = graphics.getFontMetrics().getStringBounds(headerText,
                                                              graphics);

            headerTextSpace = (int)Math.ceil(hRect.getHeight());
            availableSpace -= headerTextSpace + H_F_SPACE;
        }

        // if there's footer text, find out how much space is needed for it
        // and subtract that from the available space
        if (footerText != null) {
            graphics.setFont(footerFont);
            fRect = graphics.getFontMetrics().getStringBounds(footerText,
                                                              graphics);

            footerTextSpace = (int)Math.ceil(fRect.getHeight());
            availableSpace -= footerTextSpace + H_F_SPACE;
        }

        if (availableSpace <= 0) {
            throw new PrinterException("Height of printable area is too small.");
        }

        // depending on the print mode, we may need a scale factor to
        // fit the table's entire width on the page
        double sf = 1.0D;
        if (printMode == JTable.PrintMode.FIT_WIDTH &&
                totalColWidth > imgWidth) {

            // if not, we would have thrown an acception previously
            assert imgWidth > 0;

            // it must be, according to the if-condition, since imgWidth > 0
            assert totalColWidth > 1;

            sf = (double)imgWidth / (double)totalColWidth;
        }

        // dictated by the previous two assertions
        assert sf > 0;

        // This is in a loop for two reasons:
        // First, it allows us to catch up in case we're called starting
        // with a non-zero pageIndex. Second, we know that we can be called
        // for the same page multiple times. The condition of this while
        // loop acts as a check, ensuring that we don't attempt to do the
        // calculations again when we are called subsequent times for the
        // same page.
        while (last < pageIndex) {
            // if we are finished all columns in all rows
            if (row >= table.getRowCount() && col == 0) {
                return NO_SUCH_PAGE;
            }

            // rather than multiplying every row and column by the scale factor
            // in findNextClip, just pass a width and height that have already
            // been divided by it
            int scaledWidth = (int)(imgWidth / sf);
            int scaledHeight = (int)((availableSpace - hclip.height) / sf);

            // calculate the area of the table to be printed for this page
            findNextClip(scaledWidth, scaledHeight);

            last++;
        }

        // create a copy of the graphics so we don't affect the one given to us
        Graphics2D g2d = (Graphics2D)graphics.create();

        // translate into the co-ordinate system of the pageFormat
        g2d.translate(pageFormat.getImageableX(), pageFormat.getImageableY());

        // to save and store the transform
        AffineTransform oldTrans;

        // if there's footer text, print it at the bottom of the imageable area
        if (footerText != null) {
            oldTrans = g2d.getTransform();

            g2d.translate(0, imgHeight - footerTextSpace);

            printText(g2d, footerText, fRect, footerFont, imgWidth);

            g2d.setTransform(oldTrans);
        }

        // if there's header text, print it at the top of the imageable area
        // and then translate downwards
        if (headerText != null) {
            printText(g2d, headerText, hRect, headerFont, imgWidth);

            g2d.translate(0, headerTextSpace + H_F_SPACE);
        }

        // constrain the table output to the available space
        tempRect.x = 0;
        tempRect.y = 0;
        tempRect.width = imgWidth;
        tempRect.height = availableSpace;
        g2d.clip(tempRect);

        // if we have a scale factor, scale the graphics object to fit
        // the entire width
        if (sf != 1.0D) {
            g2d.scale(sf, sf);

        // otherwise, ensure that the current portion of the table is
        // centered horizontally
        } else {
            int diff = (imgWidth - clip.width) / 2;
            g2d.translate(diff, 0);
        }

        // store the old transform and clip for later restoration
        oldTrans = g2d.getTransform();
        Shape oldClip = g2d.getClip();

        // if there's a table header, print the current section and
        // then translate downwards
        if (header != null) {
            hclip.x = clip.x;
            hclip.width = clip.width;

            g2d.translate(-hclip.x, 0);
            g2d.clip(hclip);
            header.print(g2d);

            // restore the original transform and clip
            g2d.setTransform(oldTrans);
            g2d.setClip(oldClip);

            // translate downwards
            g2d.translate(0, hclip.height);
        }

        // print the current section of the table
        g2d.translate(-clip.x, -clip.y);
        g2d.clip(clip);
        table.print(g2d);

        // restore the original transform and clip
        g2d.setTransform(oldTrans);
        g2d.setClip(oldClip);

        // draw a box around the table
        g2d.setColor(Color.BLACK);
        g2d.drawRect(0, 0, clip.width, hclip.height + clip.height);

        // dispose the graphics copy
        g2d.dispose();

        return PAGE_EXISTS;
    }

    
A helper method that encapsulates common code for rendering the
header and footer text.

Params:
  • g2d –       the graphics to draw into
  • text –      the text to draw, non null
  • rect –      the bounding rectangle for this text,
                  as calculated at the given font, non null
  • font –      the font to draw the text in, non null
  • imgWidth –  the width of the area to draw into
/**
     * A helper method that encapsulates common code for rendering the
     * header and footer text.
     *
     * @param  g2d       the graphics to draw into
     * @param  text      the text to draw, non null
     * @param  rect      the bounding rectangle for this text,
     *                   as calculated at the given font, non null
     * @param  font      the font to draw the text in, non null
     * @param  imgWidth  the width of the area to draw into
     */
    private void printText(Graphics2D g2d,
                           String text,
                           Rectangle2D rect,
                           Font font,
                           int imgWidth) {

            int tx;

            // if the text is small enough to fit, center it
            if (rect.getWidth() < imgWidth) {
                tx = (int)((imgWidth - rect.getWidth()) / 2);

            // otherwise, if the table is LTR, ensure the left side of
            // the text shows; the right can be clipped
            } else if (table.getComponentOrientation().isLeftToRight()) {
                tx = 0;

            // otherwise, ensure the right side of the text shows
            } else {
                tx = -(int)(Math.ceil(rect.getWidth()) - imgWidth);
            }

            int ty = (int)Math.ceil(Math.abs(rect.getY()));
            g2d.setColor(Color.BLACK);
            g2d.setFont(font);
            g2d.drawString(text, tx, ty);
    }

    
Calculate the area of the table to be printed for
the next page. This should only be called if there
are rows and columns left to print.
To avoid an infinite loop in printing, this will
always put at least one cell on each page.

Params:
  • pw –  the width of the area to print in
  • ph –  the height of the area to print in
/**
     * Calculate the area of the table to be printed for
     * the next page. This should only be called if there
     * are rows and columns left to print.
     *
     * To avoid an infinite loop in printing, this will
     * always put at least one cell on each page.
     *
     * @param  pw  the width of the area to print in
     * @param  ph  the height of the area to print in
     */
    private void findNextClip(int pw, int ph) {
        final boolean ltr = table.getComponentOrientation().isLeftToRight();

        // if we're ready to start a new set of rows
        if (col == 0) {
            if (ltr) {
                // adjust clip to the left of the first column
                clip.x = 0;
            } else {
                // adjust clip to the right of the first column
                clip.x = totalColWidth;
            }

            // adjust clip to the top of the next set of rows
            clip.y += clip.height;

            // adjust clip width and height to be zero
            clip.width = 0;
            clip.height = 0;

            // fit as many rows as possible, and at least one
            int rowCount = table.getRowCount();
            int rowHeight = table.getRowHeight(row);
            do {
                clip.height += rowHeight;

                if (++row >= rowCount) {
                    break;
                }

                rowHeight = table.getRowHeight(row);
            } while (clip.height + rowHeight <= ph);
        }

        // we can short-circuit for JTable.PrintMode.FIT_WIDTH since
        // we'll always fit all columns on the page
        if (printMode == JTable.PrintMode.FIT_WIDTH) {
            clip.x = 0;
            clip.width = totalColWidth;
            return;
        }

        if (ltr) {
            // adjust clip to the left of the next set of columns
            clip.x += clip.width;
        }

        // adjust clip width to be zero
        clip.width = 0;

        // fit as many columns as possible, and at least one
        int colCount = table.getColumnCount();
        int colWidth = colModel.getColumn(col).getWidth();
        do {
            clip.width += colWidth;
            if (!ltr) {
                clip.x -= colWidth;
            }

            if (++col >= colCount) {
                // reset col to 0 to indicate we're finished all columns
                col = 0;

                break;
            }

            colWidth = colModel.getColumn(col).getWidth();
        } while (clip.width + colWidth <= pw);

    }

}