NSPrintOperation

Inherits From: NSObject

Conforms To: NSObject (NSObject)

Declared In: AppKit/NSPrintOperation.h

Class Description

NSPrintOperation controls operations that generate Encapsulated PostScript (EPS) code or PostScript print jobs. Generally, EPS code is used to transfer images between applications, which happens when the user copies and pastes graphics, uses a Service, or uses ObjectLinks. PostScript print jobs are generated when the user prints and faxes documents. An NSPrintOperation does not generate PostScript code itself; it just controls the overall process, relying on an NSView object to generate the actual code.

NSPrintOperation relies mainly on two other objects: an NSPrintInfo object, which specifies how the code should be generated, and an NSView object, which performs the actual code generation. You specify these two objects in the method you use to create the NSPrintOperation. If no NSPrintInfo is specified, NSPrintOperation uses the shared NSPrintInfo, which contains default values. The shared NSPrintInfo works well for applications that are not document-based. Document-based applications should create an NSPrintInfo for each document that might be printed or copied and use that object instead.

You should create an NSPrintOperation in any method that is invoked when a user executes a Print command or a Copy command. That method also must send NSPrintOperation a runOperation message to start the operation. A print: method for a document-based application might look like this:

- (void)print:sender {

[[NSPrintOperation printOperationWithView:[self myView] printInfo:[document

docPrintInfo]] runOperation];

}

This method creates an NSPrintOperation for a print job that uses the document's NSPrintInfo. Because this is a print job, a Print panel (NSPrintPanel object) is displayed to allow the user to select printing options. The NSPrintOperation copies the NSPrintInfo, updates this copy with information from the Print panel, and uses the specified NSView to perform the operation.

The information stored in an NSPrintInfo that's retained between operations is information that's likely to remain constant for a document, such as its page size. All information that's likely to change between operations is set to a default value in the NSPrintInfo before the operation begins. In this way, even though NSPrintOperation updates the NSPrintInfo with information from the Print panel for print jobs, that information is reset back to the default values for each print job. Because NSPrintOperation keeps a copy of the NSPrintInfo it uses, you could duplicate a specific print job by storing that copy and reusing it.

Creating and Initializing an NSPrintOperation Object

• + (NSPrintOperation *)EPSOperationWithView:(NSView *)aView insideRect:(NSRect)rect Returns a new NSPrintOperation that controls the toData:(NSMutableData *)data copying of EPS graphics from the area specified by rect in aView, using the parameters in the default NSPrintInfo. The code is written to data. Raises NSPrintOperationExistsException if there is already a print operation in progress.
• + (NSPrintOperation *)EPSOperationWithView:(NSView *)aView insideRect:(NSRect)rect Returns a new NSPrintOperation that controls the toData:(NSMutableData *)data copying of EPS graphics from the area specified by rect printInfo:(NSPrintInfo *)aPrintInfo in aView, using the parameters in aPrintInfo. The code is written to data. Raises NSPrintOperationExistsException if there is already a print operation in progress.
• + (NSPrintOperation *)EPSOperationWithView:(NSView *)aView insideRect:(NSRect)rect Returns a new NSPrintOperation that controls the toPath:(NSString *)path copying of EPS graphics from the area specified by rect printInfo:(NSPrintInfo *)aPrintInfo in aView, using the parameters in aPrintInfo. The code is written to path. Raises NSPrintOperationExistsException if there is already a print operation in progress.
• + (NSPrintOperation *)printOperationWithView:(NSView *)aView Returns a new NSPrintOperation that controls the printing of aView, using the parameters in the shared NSPrintInfo object. Raises NSPrintOperationExistsException if there is already a print operation in progress.
• + (NSPrintOperation *)printOperationWithView:(NSView *)aView printInfo:(NSPrintInfo *)aPrintInfo Returns a new NSPrintOperation that controls the printing of aView, using the parameters in aPrintInfo. Raises NSPrintOperationExistsException if there is already a print operation in progress.
• - (id)initEPSOperationWithView:(NSView *)aView Initializes a newly allocated NSPrintOperation to insideRect:(NSRect)rect control the copying of EPS graphics from the area toData:(NSMutableData *)data specified by rect in aView, using the parameters in printInfo:(NSPrintInfo *)aPrintInfo aPrintInfo. The code is written to data.
• - (id)initWithView:(NSView *)aView Initializes a newly allocated NSPrintOperation to printInfo:(NSPrintInfo *)aPrintInfo control the printing of aView, using the parameters in aPrintInfo.

• + (NSPrintOperation *)currentOperation Returns the NSPrintOperation that represents the current operation or nil if there is no such operation.
• + (void)setCurrentOperation:(NSPrintOperation *)operation Sets the NSPrintOperation that represents the current operation.

• - (BOOL)isEPSOperation Returns YES if the receiver controls an EPS operation and NO if the receiver controls a printing operation.

• - (NSPrintPanel *)printPanel Returns the NSPrintPanel object that's used when the operation is run.
• - (BOOL)showPanels Returns whether the Print panel will appear when the operation is run.
• - (void)setPrintPanel:(NSPrintPanel *)panel Sets the NSPrintPanel object that's used when the operation is run.
• - (void)setShowPanels:(BOOL)flag Sets whether the Print panel appears when the operation is run.

• - (NSDPSContext *)createContext Used by the NSPrintOperation object to create the DPS context for output generation, using the current NSPrintInfo settings.
• - (NSDPSContext *)context Returns the DPS context used for the receiver's operation.
• - (void)destroyContext Used by the NSPrintOperation object to destroy the DPS context at the end of the operation.

• - (int)currentPage Returns the page number of the page being printed.
• - (NSPrintingPageOrder)pageOrder Returns the order in which pages will be printed.
• - (void)setPageOrder:(NSPrintingPageOrder)order Sets the order in which pages will be printed.

• - (void)cleanUpOperation Invoked at end of an operation's run to set the current operation to nil.
• - (BOOL)deliverResult Delivers the results generated by runOperation to the intended destination: the print spooler, preview application, etc. Returns YES upon successful delivery and NO otherwise.
• - (BOOL)runOperation Causes the operation (copying EPS graphics or printing) to take place. Returns YES upon successful completion and NO otherwise.

• - (NSPrintInfo *)printInfo Returns the receiver's NSPrintInfo object.
• - (void)setPrintInfo:(NSPrintInfo *)aPrintInfo Sets the receiver's NSPrintInfo object to aPrintInfo.

• - (NSView *)view Returns the NSView object that performs the operation controlled by the receiving object.