FileDocCategorySizeDatePackage
TablePrintable.javaAPI DocJava SE 6 API18724Tue Jun 10 00:26:40 BST 2008javax.swing

TablePrintable

public class TablePrintable extends Object implements Printable
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
version
1.41 11/17/05

Fields Summary
private JTable
table
The table to print.
private JTableHeader
header
For quick reference to the table's header.
private TableColumnModel
colModel
For quick reference to the table's column model.
private int
totalColWidth
To save multiple calculations of total column width.
private JTable$PrintMode
printMode
The printing mode of this printable.
private MessageFormat
headerFormat
Provides the header text for the table.
private MessageFormat
footerFormat
Provides the footer text for the table.
private int
last
The most recent page index asked to print.
private int
row
The next row to print.
private int
col
The next column to print.
private final Rectangle
clip
Used to store an area of the table to be printed.
private final Rectangle
hclip
Used to store an area of the table's header to be printed.
private final Rectangle
tempRect
Saves the creation of multiple rectangles.
private static final int
H_F_SPACE
Vertical space to leave between table and header/footer text.
private static final float
HEADER_FONT_SIZE
Font size for the header text.
private static final float
FOOTER_FONT_SIZE
Font size for the footer text.
private Font
headerFont
The font to use in rendering header text.
private Font
footerFont
The font to use in rendering footer text.
Constructors Summary
public TablePrintable(JTable table, JTable$PrintMode printMode, MessageFormat headerFormat, MessageFormat footerFormat)
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.

param
table the table to print
param
printMode the printing mode for this printable
param
headerFormat a MessageFormat specifying the text to be used in printing a header, or null for none
param
footerFormat a MessageFormat specifying the text to be used in printing a footer, or null for none
throws
IllegalArgumentException if passed an invalid print mode


                                                                                                                                                                    
      
                           
                           
                            

        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);
Methods Summary
private voidfindNextClip(int pw, int ph)
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

        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);
public intprint(java.awt.Graphics graphics, java.awt.print.PageFormat pageFormat, int pageIndex)
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


        // 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[]{new Integer(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++;
        }

        // translate into the co-ordinate system of the pageFormat
        Graphics2D g2d = (Graphics2D)graphics;
        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);

        return PAGE_EXISTS;
private voidprintText(java.awt.Graphics2D g2d, java.lang.String text, java.awt.geom.Rectangle2D rect, java.awt.Font font, int imgWidth)
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


            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);