Question

I have a table called table and its filled with data, I also have a MessageFormat header I want to use as a header to print the JTable this is the MessageFormat:

MessageFormat header = new  MessageFormat("Product: "
                    + task.getProductName() + "  Job: "
                    + task.getJobNumber() + "  Task: " + task.getTaskID()
                    );

I want to print 3 lines in the header, one for Product, Job and Task

the way I print this table is like so:

table.print(JTable.PrintMode.FIT_WIDTH, header, null);

I can’t seem to figure out how to print the header in 3 seperate lines, I tried using the \n to make a new line but that doesn’t seem to work.

Answer 1

It’s gonna be long answer (code wise) because the only solution I found was to implement a custom Printable. Of course I didn’t write the following code myself, I mostly copied the code I extracted from the jdk sources and made some adjustments.

Here we are:

This is the way you said you invoke the print method:

DefaultTableModel dtm = new DefaultTableModel(new String[] { "Column 1" }, 1);

JTable table = new JTable(dtm) {
@Override
    public Printable getPrintable(PrintMode printMode, MessageFormat headerFormat, MessageFormat footerFormat) {
       return new TablePrintable(this, printMode, headerFormat, footerFormat);
    }
};

where TablePrintable is the following class (sorry for not being concise here):

static class TablePrintable implements Printable {

    private final JTable table;
    private final JTableHeader header;
    private final TableColumnModel colModel;
    private final int totalColWidth;
    private final JTable.PrintMode printMode;
    private final MessageFormat headerFormat;
    private final MessageFormat footerFormat;
    private int last = -1;
    private int row = 0;
    private int col = 0;
    private final Rectangle clip = new Rectangle(0, 0, 0, 0);
    private final Rectangle hclip = new Rectangle(0, 0, 0, 0);
    private final Rectangle tempRect = new Rectangle(0, 0, 0, 0);
    private static final int H_F_SPACE = 8;
    private static final float HEADER_FONT_SIZE = 18.0f;
    private static final float FOOTER_FONT_SIZE = 12.0f;
    private final Font headerFont;
    private final Font footerFont;

    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);
    }

    @Override
    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);
            int nbLines = headerText.split("\n").length;
            hRect = graphics.getFontMetrics().getStringBounds(headerText, graphics);

            hRect = new Rectangle2D.Double(hRect.getX(), Math.abs(hRect.getY()), hRect.getWidth(),
                    hRect.getHeight() * nbLines);

            headerTextSpace = (int) Math.ceil(hRect.getHeight() * nbLines);
            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);

            String[] lines = footerText.split("\n");
            printText(g2d, lines, 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) {
            String[] lines = headerText.split("\n");
            printText(g2d, lines, 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;
    }

    private void printText(Graphics2D g2d, String[] lines, Rectangle2D rect, Font font, int imgWidth) {

        g2d.setColor(Color.BLACK);
        g2d.setFont(font);

        for (int i = 0; i < lines.length; i++) {
            int tx;

            // if the text is small enough to fit, center it
            if (rect.getWidth() < imgWidth) {
                tx = (int) (imgWidth / 2 - g2d.getFontMetrics().getStringBounds(lines[i], g2d).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() + i * rect.getHeight() / lines.length));
            g2d.drawString(lines[i], tx, ty);
        }
    }

    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);

    }
}

And here is the result (I hope that’s what you expect):