Java Reference
In-Depth Information
// Print the window
public int print(Graphics g,
PageFormat pageFormat,
int pageIndex)
throws PrinterException {
if(pageIndex>0) // Only one page page 0 to be printed
return NO
_
SUCH
_
PAGE;
// Scale the component to fit
Graphics2D g2D = (Graphics2D) g;
// Calculate the scale factor to fit the window to the page
double scaleX = pageFormat.getImageableWidth()/getWidth();
double scaleY = pageFormat.getImageableHeight()/getHeight();
double scale = Math.min(scaleX,scaleY); // Get minimum scale factor
// Move paper origin to page printing area corner
g2D.translate(pageFormat.getImageableX(), pageFormat.getImageableY());
g2D.scale(scale,scale); // Apply the scale factor
print(g2D); // Draw the component
return PAGE
_
EXISTS;
}
Make sure you have the necessary additional imports:
import javax.print.PrintService;
import javax.print.attribute.PrintRequestAttributeSet;
import javax.print.attribute.HashPrintRequestAttributeSet;
If you recompile and run Sketcher once more, the
F
ile | Print
window menu item should be operational.
How It Works
The menu operation and the printing mechanism are as we have already discussed. The
SketchFrame
object is the page painter for the window so the
print()
method is where it all happens. After
checking the page index value and casting the
Graphics
reference passed to the method to
Graphics2D
, we calculate the scaling factor to fit the window to the page. The
getWidth()
and
getHeight()
methods inherited in our
SketchFrame
class return the width and height of the
window respectively. We then apply the scale just as we did for printing a sketch. The coordinates of the
top left corner of the window are at (0,0) so we can just print it once we have applied the scaling factor.
Calling the inherited
print()
method with
g2D
as the argument does this.
I'm sure you will have noticed that the output has deficiencies. The title bar and window boundary are
missing. Of course, a
JFrame
object is a top-level window, and since it is derived from the
Frame
class
it is a heavyweight component with its appearance determined by its peer, which is outside the Java
code. The
print()
method for the
JFrame
object that we call to print the window does not include
the peer created elements of the window. The
printAll()
method does though. Modify the code in
the
print()
method to call
printAll()
rather than
print()
, like this :
