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:
*
ComponentOrientation.
* 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
*/
class TablePrintable implements Printable {
/** The table to print. */
private JTable table;
/** For quick reference to the table's header. */
private JTableHeader header;
/** For quick reference to the table's column model. */
private TableColumnModel colModel;
/** To save multiple calculations of total column width. */
private int totalColWidth;
/** The printing mode of this printable. */
private JTable.PrintMode printMode;
/** Provides the header text for the table. */
private MessageFormat headerFormat;
/** Provides the footer text for the table. */
private MessageFormat footerFormat;
/** The most recent page index asked to print. */
private int last = -1;
/** The next row to print. */
private int row = 0;
/** The next column to print. */
private int col = 0;
/** 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. */
private final Rectangle hclip = new Rectangle(0, 0, 0, 0);
/** 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. */
private static final int H_F_SPACE = 8;
/** Font size for the header text. */
private static final float HEADER_FONT_SIZE = 18.0f;
/** Font size for the footer text. */
private static final float FOOTER_FONT_SIZE = 12.0f;
/** The font to use in rendering header text. */
private Font headerFont;
/** 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.
*
* @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
*/
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 {@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.
*
* @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.
*
* @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);
}
}