QPrinter Class Reference
^{[QtGui module]}

Detailed Description

The QPrinter class is a paint device that paints on a printer.

This device represents a series of pages of printed output, and is used in almost exactly the same way as other paint devices such as QWidget and QPixmap. A set of additional functions are provided to manage device-specific features, such as orientation and resolution, and to step through the pages in a document as it is generated.

When printing directly to a printer on Windows or Mac OS X, QPrinter uses the built-in printer drivers. On X11, QPrinter uses the Common Unix Printing System (CUPS) or the standard Unix lpr utility to send PostScript or PDF output to the printer. As an alternative, the printProgram() function can be used to specify the command or utility to use instead of the system default.

QPrinter supports a number of parameters, most of which can be changed by the end user through a print dialog. In general, QPrinter passes these functions onto the underlying QPrintEngine.

The most important parameters are:

• setOrientation() tells QPrinter which page orientation to use.
• setPageSize() tells QPrinter what page size to expect from the printer.
• setResolution() tells QPrinter what resolution you wish the printer to provide, in dots per inch (DPI).
• setFullPage() tells QPrinter whether you want to deal with the full page or just with the part the printer can draw on.
• setNumCopies() tells QPrinter how many copies of the document it should print.

Many of these functions can only be called before the actual printing begins (i.e., before QPainter::begin() is called). This usually makes sense because, for example, it's not possible to change the number of copies when you are halfway through printing. There are also some settings that the user sets (through the printer dialog) and that applications are expected to obey. See QAbstractPrintDialog's documentation for more details.

When QPainter::begin() is called, the QPrinter it operates on is prepared for a new page, enabling the QPainter to be used immediately to paint the first page in a document. Once the first page has been painted, newPage() can be called to request a new blank page to paint on, or QPainter::end() can be called to finish printing. The second page and all following pages are prepared using a call to newPage() before they are painted.

The first page in a document does not need to be preceded by a call to newPage(). You only need to calling newPage() after QPainter::begin() if you need to insert a blank page at the beginning of a printed document. Similarly, calling newPage() after the last page in a document is painted will result in a trailing blank page appended to the end of the printed document.

If you want to abort the print job, abort() will try its best to stop printing. It may cancel the entire job or just part of it.

Since QPrinter can print to any QPrintEngine subclass, it is possible to extend printing support to cover new types of printing subsystem by subclassing QPrintEngine and reimplementing its interface.

See also QPrintDialog and Printing with Qt.

Member Type Documentation

enum QPrinter::ColorMode

This enum type is used to indicate whether QPrinter should print in color or not.

enum QPrinter::Orientation

This enum type (not to be confused with Orientation) is used to specify each page's orientation.

This type interacts with QPrinter::PageSize and QPrinter::setFullPage() to determine the final size of the page available to the application.

enum QPrinter::OutputFormat

The OutputFormat enum is used to describe the format QPrinter should use for printing.

See also outputFormat(), setOutputFormat(), and setOutputFileName().

enum QPrinter::PageOrder

This enum type is used by QPrinter to tell the application program how to print.

enum QPrinter::PageSize

This enum type specifies what paper size QPrinter should use. QPrinter does not check that the paper size is available; it just uses this information, together with QPrinter::Orientation and QPrinter::setFullPage(), to determine the printable area.

The defined sizes (with setFullPage(true)) are:

With setFullPage(false) (the default), the metrics will be a bit smaller; how much depends on the printer in use.

enum QPrinter::PaperSource

This enum type specifies what paper source QPrinter is to use. QPrinter does not check that the paper source is available; it just uses this information to try and set the paper source. Whether it will set the paper source depends on whether the printer has that particular source.

Warning: This is currently only implemented for Windows.

enum QPrinter::PrintRange

Used to specify the print range selection option.

See also QAbstractPrintDialog::PrintRange.

enum QPrinter::PrinterMode

This enum describes the mode the printer should work in. It basically presets a certain resolution and working mode.

Note: When rendering text on a QPrinter device, it is important to realize that the size of text, when specified in points, is independent of the resolution specified for the device itself. Therefore, it may be useful to specify the font size in pixels when combining text with graphics to ensure that their relative sizes are what you expect.

enum QPrinter::PrinterState

Member Function Documentation

QPrinter::QPrinter ( PrinterMode mode = ScreenResolution )

Creates a new printer object with the given mode.

QPrinter::~QPrinter ()

Destroys the printer object and frees any allocated resources. If the printer is destroyed while a print job is in progress this may or may not affect the print job.

bool QPrinter::abort ()

Aborts the current print run. Returns true if the print run was successfully aborted and printerState() will return QPrinter::Aborted; otherwise returns false.

It is not always possible to abort a print job. For example, all the data has gone to the printer but the printer cannot or will not cancel the job when asked to.

bool QPrinter::collateCopies () const

Returns true if collation is turned on when multiple copies is selected. Returns false if it is turned off when multiple copies is selected.

This function was introduced in Qt 4.1.

See also setCollateCopies().

ColorMode QPrinter::colorMode () const

Returns the current color mode.

See also setColorMode().

QString QPrinter::creator () const

Returns the name of the application that created the document.

See also setCreator().

QString QPrinter::docName () const

Returns the document name.

See also setDocName().

bool QPrinter::doubleSidedPrinting () const

Returns true if double side printing is enabled.

Currently this option is only supported on X11.

This function was introduced in Qt 4.2.

See also setDoubleSidedPrinting().

bool QPrinter::fontEmbeddingEnabled () const

Returns true if font embedding is enabled.

Currently this option is only supported on X11.

This function was introduced in Qt 4.1.

See also setFontEmbeddingEnabled().

int QPrinter::fromPage () const

Returns the from-page setting. The default value is 0.

If fromPage() and toPage() both return 0 this signifies 'print the whole document'.

This function was introduced in Qt 4.1.

See also setFromTo() and toPage().

bool QPrinter::fullPage () const

Returns true if the origin of the printer's coordinate system is at the corner of the page and false if it is at the edge of the printable area.

See setFullPage() for details and caveats.

See also setFullPage() and PageSize.

bool QPrinter::newPage ()

Tells the printer to eject the current page and to continue printing on a new page. Returns true if this was successful; otherwise returns false.

int QPrinter::numCopies () const

Returns the number of copies to be printed. The default value is 1.

On Windows, Mac OS X and X11 systems that support CUPS, this will always return 1 as these operating systems can internally handle the number of copies.

On X11, this value will return the number of times the application is required to print in order to match the number specified in the printer setup dialog. This has been done since some printer drivers are not capable of buffering up the copies and in those cases the application must make an explicit call to the print code for each copy.

See also setNumCopies().

Orientation QPrinter::orientation () const

Returns the orientation setting. This is driver-dependent, but is usually QPrinter::Portrait.

See also setOrientation().

QString QPrinter::outputFileName () const

Returns the name of the output file. By default, this is an empty string (indicating that the printer shouldn't print to file).

See also setOutputFileName().

OutputFormat QPrinter::outputFormat () const

Returns the output format for this printer.

This function was introduced in Qt 4.1.

See also setOutputFormat().

PageOrder QPrinter::pageOrder () const

Returns the current page order.

The default page order is FirstPageFirst.

See also setPageOrder().

QRect QPrinter::pageRect () const

Returns the page's rectangle; this is usually smaller than the paperRect() since the page normally has margins between its borders and the paper.

See also pageSize().

PageSize QPrinter::pageSize () const

Returns the printer page size. The default value is driver-dependent.

See also setPageSize(), pageRect(), and paperRect().

QPaintEngine * QPrinter::paintEngine () const   [virtual]

Returns the paint engine used by the printer.

Reimplemented from QPaintDevice.

QRect QPrinter::paperRect () const

Returns the paper's rectangle; this is usually larger than the pageRect().

See also pageRect().

PaperSource QPrinter::paperSource () const

Returns the printer's paper source. This is Manual or a printer tray or paper cassette.

See also setPaperSource().

QPrintEngine * QPrinter::printEngine () const

Returns the print engine used by the printer.

This function was introduced in Qt 4.1.

QString QPrinter::printProgram () const

Returns the name of the program that sends the print output to the printer.

The default is to return an empty string; meaning that QPrinter will try to be smart in a system-dependent way. On X11 only, you can set it to something different to use a specific print program. On the other platforms, this returns an empty string.

See also setPrintProgram() and setPrinterSelectionOption().

PrintRange QPrinter::printRange () const

Returns the page range of the QPrinter. After the print setup dialog has been opened, this function returns the value selected by the user.

This function was introduced in Qt 4.1.

See also setPrintRange().

QString QPrinter::printerName () const

Returns the printer name. This value is initially set to the name of the default printer.

See also setPrinterName().

QString QPrinter::printerSelectionOption () const

Returns the printer options selection string. This is useful only if the print command has been explicitly set.

The default value (an empty string) implies that the printer should be selected in a system-dependent manner.

Any other value implies that the given value should be used.

Warning: This function is not available on Windows.

See also setPrinterSelectionOption().

PrinterState QPrinter::printerState () const

Returns the current state of the printer. This may not always be accurate (for example if the printer doesn't have the capability of reporting its state to the operating system).

int QPrinter::resolution () const

Returns the current assumed resolution of the printer, as set by setResolution() or by the printer driver.

See also setResolution().

void QPrinter::setCollateCopies ( bool collate )

Sets the default value for collation checkbox when the print dialog appears. If collate is true, it will enable setCollateCopiesEnabled(). The default value is false. This value will be changed by what the user presses in the print dialog.

This function was introduced in Qt 4.1.

See also collateCopies().

void QPrinter::setColorMode ( ColorMode newColorMode )

Sets the printer's color mode to newColorMode, which can be either Color or GrayScale.

See also colorMode().

void QPrinter::setCreator ( const QString & creator )

Sets the name of the application that created the document to creator.

This function is only applicable to the X11 version of Qt. If no creator name is specified, the creator will be set to "Qt" followed by some version number.

See also creator().

void QPrinter::setDocName ( const QString & name )

Sets the document name to name.

See also docName().

void QPrinter::setDoubleSidedPrinting ( bool doubleSided )

Enables double sided printing if doubleSided is true; otherwise disables it.

Currently this option is only supported on X11.

This function was introduced in Qt 4.2.

See also doubleSidedPrinting().

void QPrinter::setEngines ( QPrintEngine * printEngine, QPaintEngine * paintEngine )   [protected]

This function is used by subclasses of QPrinter to specify custom print and paint engines (printEngine and paintEngine, respectively).

QPrinter does not take ownership of the engines, so you need to manage these engine instances yourself.

Note that changing the engines will reset the printer state and all its properties.

This function was introduced in Qt 4.1.

See also printEngine(), paintEngine(), and setOutputFormat().

void QPrinter::setFontEmbeddingEnabled ( bool enable )

Enabled or disables font embedding depending on enable.

Currently this option is only supported on X11.

This function was introduced in Qt 4.1.

See also fontEmbeddingEnabled().

void QPrinter::setFromTo ( int from, int to )

Sets the from-page and to-page settings to from and to respectively.

The from-page and to-page settings specify what pages to print.

If from and to both return 0 this signifies 'print the whole document'.

This function is useful mostly to set a default value that the user can override in the print dialog when you call setup().

This function was introduced in Qt 4.1.

See also fromPage() and toPage().

void QPrinter::setFullPage ( bool fp )

If fp is true, enables support for painting over the entire page; otherwise restricts painting to the printable area reported by the device.

By default, full page printing is disabled. In this case, the origin of the QPrinter's coordinate system coincides with the top-left corner of the printable area.

If full page printing is enabled, the origin of the QPrinter's coordinate system coincides with the top-left corner of the paper itself. In this case, the device metrics will report the exact same dimensions as indicated by PageSize. It may not be possible to print on the entire physical page because of the printer's margins, so the application must account for the margins itself.

See also fullPage(), setPageSize(), width(), height(), and Printing with Qt.

void QPrinter::setNumCopies ( int numCopies )

Sets the number of copies to be printed to numCopies.

The printer driver reads this setting and prints the specified number of copies.

See also numCopies().

void QPrinter::setOrientation ( Orientation orientation )

Sets the print orientation to orientation.

The orientation can be either QPrinter::Portrait or QPrinter::Landscape.

The printer driver reads this setting and prints using the specified orientation.

On Windows, this option can be changed while printing and will take effect from the next call to newPage().

On Mac OS X, changing the orientation during a print job has no effect.

See also orientation().

void QPrinter::setOutputFileName ( const QString & fileName )

Sets the name of the output file to fileName.

Setting a null or empty name (0 or "") disables printing to a file. Setting a non-empty name enables printing to a file.

This can change the value of outputFormat(). If the file name has the suffix ".ps" then PostScript is automatically selected as output format. If the file name has the ".pdf" suffix PDF is generated. QPrinter will use Qt's cross-platform PostScript or PDF print engines respectively. If you can produce this format natively, for example Mac OS X can generate PDF's from its print engine, set the output format back to NativeFormat.

See also outputFileName(), setOutputToFile(), and setOutputFormat().

void QPrinter::setOutputFormat ( OutputFormat format )

Sets the output format for this printer to format.

This function was introduced in Qt 4.1.

See also outputFormat().

void QPrinter::setPageOrder ( PageOrder pageOrder )

Sets the page order to pageOrder.

The page order can be QPrinter::FirstPageFirst or QPrinter::LastPageFirst. The application is responsible for reading the page order and printing accordingly.

This function is mostly useful for setting a default value that the user can override in the print dialog.

See also pageOrder().

void QPrinter::setPageSize ( PageSize newPageSize )

Sets the printer page size to newPageSize if that size is supported. The result if undefined if newPageSize is not supported.

The default page size is driver-dependent.

This function is useful mostly for setting a default value that the user can override in the print dialog.

See also pageSize(), PageSize, setFullPage(), setResolution(), pageRect(), and paperRect().

void QPrinter::setPaperSource ( PaperSource source )

Sets the paper source setting to source.

Windows only: This option can be changed while printing and will take effect from the next call to newPage()

See also paperSource().

void QPrinter::setPrintProgram ( const QString & printProg )

Sets the name of the program that should do the print job to printProg.

On X11, this function sets the program to call with the PostScript output. On other platforms, it has no effect.

See also printProgram().

void QPrinter::setPrintRange ( PrintRange range )

Sets the print range option in to be range.

This function was introduced in Qt 4.1.

See also printRange().

void QPrinter::setPrinterName ( const QString & name )

Sets the printer name to name.

See also printerName().

void QPrinter::setPrinterSelectionOption ( const QString & option )

Sets the printer to use option to select the printer. option is null by default (which implies that Qt should be smart enough to guess correctly), but it can be set to other values to use a specific printer selection option.

If the printer selection option is changed while the printer is active, the current print job may or may not be affected.

Warning: This function is not available on Windows.

See also printerSelectionOption().

void QPrinter::setResolution ( int dpi )

Requests that the printer prints at dpi or as near to dpi as possible.

This setting affects the coordinate system as returned by, for example QPainter::viewport().

This function must be called before QPainter::begin() to have an effect on all platforms.

See also resolution() and setPageSize().

void QPrinter::setWinPageSize ( int pageSize )

Sets the page size to be used by the printer under Windows to pageSize.

Warning: This function is not portable so you may prefer to use setPageSize() instead.

See also winPageSize().

QList<PaperSource> QPrinter::supportedPaperSources () const

Returns the supported paper sizes for this printer.

The values will be either a value that matches an entry in the QPrinter::PaperSource enum or a driver spesific value. The driver spesific values are greater than the constant DMBIN_USER declared in wingdi.h.

Warning: This function is only available in windows.

QList<int> QPrinter::supportedResolutions () const

Returns a list of the resolutions (a list of dots-per-inch integers) that the printer says it supports.

For X11 where all printing is directly to postscript, this function will always return a one item list containing only the postscript resolution, i.e., 72 (72 dpi -- but see PrinterMode).

int QPrinter::toPage () const

Returns the to-page setting. The default value is 0.

If fromPage() and toPage() both return 0 this signifies 'print the whole document'.

The programmer is responsible for reading this setting and printing accordingly.

This function was introduced in Qt 4.1.

See also setFromTo() and fromPage().

int QPrinter::winPageSize () const

Returns the page size used by the printer under Windows.

Warning: This function is not portable so you may prefer to use pageSize() instead.

See also setWinPageSize().