Interface Printable
Printable
interface is implemented
by the print
methods of the current
page painter, which is called by the printing
system to render a page. When building a
Pageable
, pairs of PageFormat
instances and instances that implement
this interface are used to describe each page. The
instance implementing Printable
is called to
print the page's graphics.
A Printable(..)
may be set on a PrinterJob
.
When the client subsequently initiates printing by calling
PrinterJob.print(..)
control
is handed to the printing system until all pages have been printed.
It does this by calling Printable.print(..)
until
all pages in the document have been printed.
In using the Printable
interface the printing
commits to image the contents of a page whenever
requested by the printing system.
The parameters to Printable.print(..)
include a
PageFormat
which describes the printable area of
the page, needed for calculating the contents that will fit the
page, and the page index, which specifies the zero-based print
stream index of the requested page.
For correct printing behaviour, the following points should be observed:
- The printing system may request a page index more than once. On each occasion equal PageFormat parameters will be supplied.
- The printing system will call
Printable.print(..)
with page indexes which increase monotonically, although as noted above, thePrintable
should expect multiple calls for a page index and that page indexes may be skipped, when page ranges are specified by the client, or by a user through a print dialog. - If multiple collated copies of a document are requested, and the printer cannot natively support this, then the document may be imaged multiple times. Printing will start each copy from the lowest print stream page index page.
- With the exception of re-imaging an entire document for multiple collated copies, the increasing page index order means that when page N is requested if a client needs to calculate page break position, it may safely discard any state related to pages < N, and make current that for page N. "State" usually is just the calculated position in the document that corresponds to the start of the page.
- When called by the printing system the
Printable
must inspect and honour the supplied PageFormat parameter as well as the page index. The format of the page to be drawn is specified by the supplied PageFormat. The size, orientation and imageable area of the page is therefore already determined and rendering must be within this imageable area. This is key to correct printing behaviour, and it has the implication that the client has the responsibility of tracking what content belongs on the specified page. - When the
Printable
is obtained from a client-suppliedPageable
then the client may provide different PageFormats for each page index. Calculations of page breaks must account for this.
- See Also:
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Field Summary
Modifier and TypeFieldDescriptionstatic final int
Returned fromprint
to signify that thepageIndex
is too large and that the requested page does not exist.static final int
Returned fromprint(Graphics, PageFormat, int)
to signify that the requested page was rendered. -
Method Summary
Modifier and TypeMethodDescriptionint
print
(Graphics graphics, PageFormat pageFormat, int pageIndex) Prints the page at the specified index into the specifiedGraphics
context in the specified format.
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Field Details
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PAGE_EXISTS
static final int PAGE_EXISTSReturned fromprint(Graphics, PageFormat, int)
to signify that the requested page was rendered.- See Also:
-
NO_SUCH_PAGE
static final int NO_SUCH_PAGEReturned fromprint
to signify that thepageIndex
is too large and that the requested page does not exist.- See Also:
-
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Method Details
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print
Prints the page at the specified index into the specifiedGraphics
context in the specified format. APrinterJob
calls thePrintable
interface to request that a page be rendered into the context specified bygraphics
. The format of the page to be drawn is specified bypageFormat
. The zero based index of the requested page is specified bypageIndex
. If the requested page does not exist then this method returns NO_SUCH_PAGE; otherwise PAGE_EXISTS is returned. TheGraphics
class or subclass implements thePrinterGraphics
interface to provide additional information. If thePrintable
object aborts the print job then it throws aPrinterException
.- Parameters:
graphics
- the context into which the page is drawnpageFormat
- the size and orientation of the page being drawnpageIndex
- the zero based index of the page to be drawn- Returns:
- PAGE_EXISTS if the page is rendered successfully
or NO_SUCH_PAGE if
pageIndex
specifies a non-existent page. - Throws:
PrinterException
- thrown when the print job is terminated.
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