O
- object
- (1) In object-oriented programming, an execution-time structure that contains data and routines that operate on that data. An object is an instance of a class, which can be used to create additional instances that constitute separate objects. (2) The field of an NBP entity name that identifies the user of the system or the system itself, in the case of a server. (3) A private QuickDraw GX data structure. An object has specific properties and is accessed through a reference.
- object accessor dispatch table
- A table in either the application heap or the system heap that the Apple Event Manager uses to map descriptions of objects in an object specifier record to object accessor functions that can locate those objects.
- object accessor function
- An application- defined function that locates an Apple event object of a specified object class in a container identified by a token of a specified descriptor type.
- object callback function
- An application- defined function used by the Apple Event Manager to resolve object specifier records
See also: error callback function, marking callback functions, object-comparison function, object-counting function, token disposal function
- object class
- A category for Apple event objects that share specific characteristics listed in an object class definition in the Apple Event Registry: Standard Suites. Among these characteristics are properties, element classes, and Apple events that can specify objects of that class. An object class is specified in an object specifier record by a keyword-specified descriptor record with the keyword keyAEDesiredClass whose data handle refers to either a constant or an object class ID.
- object class ID
- A four-character code, which can also be represented by a constant, that identifies an object class for an Apple event object. The object class ID for a primitive object class is the same as the four-character value of its descriptor type.
- object class inheritance hierarchy
- The hierarchy of subclasses and superclasses that determines which properties, elements, and Apple events object classes inherit from other object classes.
- object filtering
- The process of determining whether a file object should be displayed to the user.
- object sharing
- The use of the same object by several owners, such as application variables or other objects. Many QuickDraw GX objects can be shared
See also: clone, owner count
- object specifier record
- A description of one or more Apple event objects based on the Apple Event Manager and the classification system defined in the Apple Event Registry: Standard Suites. An object specifier record consists of a descriptor record of descriptor type typeObjectSpecifier that comprises four keyword-specified descriptor records: the object class ID, the container for the Apple event object (which is usually another Apple event object, specified by another object specifier record), the key form, and the key data.
- object-comparison function
- An object callback function that compares an element to either another element or to a descriptor record and returns either TRUE or FALSE.
- object-counting function
- An object callback function that counts the number of elements of a specified class in a specified container, so that the Apple Event Manager can determine how many elements it must examine to find the element or elements that pass a test.
- object-marking function
- An object callback function called repeatedly by the Apple Event Manager to mark specific Apple event objects
See also: marking callback functions
- offline volume
- A volume that has been mounted but made temporarily unavailable (for example, because it was ejected).
- offscreen bitmap
- A bitmap that exists in memory or on disk but is not associated with a physical display device.
- offscreen drawing
- The process of drawing into an offscreen buffer in preparation for later transfer of the drawn image to the screen.
- offscreen graphics world
- A sophisticated environment for preparing complex color or black-and-white images before displaying them on the screen. An offscreen graphics world is defined in a private data structure referred to by a pointer of type GWorldPtr.
- offset point
- The point in a region whose horizontal and vertical offsets from the upper-left corner of the region's enclosing rectangle are the same as the offsets of a specified point. The DrayGrayRgn function uses an offset point to limit the motion of a region and to calculate the distance a region has moved.
- offset-binary encoding
- A method of digitally encoding sound that represents the range of amplitude values as an unsigned number, with the midpoint of the range representing silence. For example, an 8-bit sound stored in offset-binary format would contain sample values ranging from 0 to 255, with a value of 128 specifying silence (no amplitude). Samples in Macintosh sound resources are stored in offset-binary form
See also: two's complement encoding
- offspring
- For a given directory, the set of files and directories the given directory contains.
- off-curve control point
See: control point
- off-curve point
- An outline point between two on-curve points that determines the curve of the line between the two on-curve points. A Bezier curve is defined by all three points.
- omit byte
- A means of assigning different data compressions to type constants and object properties that immediately follow this byte.
- omit byte mask
- With the omit byte shift, this is a means of interpreting the meaning of each of the bits in an omit byte.
- omit byte shift
- With the omit byte mask, this is a means of interpreting the meaning of each of the bits in an omit byte.
- online mode
- A mode of operation available only to personal MSAMs in which the MSAM actively manages letters in a user's AOCE mailbox and in the user's accounts on external messaging systems, reflecting changes in one to the other, keeping both ends synchronized to the degree possible.
- online volume
- A volume that has been mounted and is currently available for File Manager operations.
- onscreen view group
- The view group, created by QuickDraw GX, that includes all view devices for physical display devices.
- on-curve point
- One of the outline points that determines the shape of a Bezier curve. Two on-curve points and one off-curve point are required to define the curve.
- opcode
- A value passed to a routine, such as the DrawPicture or PrGeneral procedure, that determines how the routine should operate
See also: operation code
- open application
- An application that is loaded into memory.
- Open Application event
- An Apple event that asks an application to perform the tasks"such as displaying untitled windows"associated with opening itself; one of the four required Apple events.
- open connection
- An association or connection set up between two sockets in which both ends have been established so that data can flow between them.
- Open Documents event
- An Apple event that asks an application to open one or more documents specified in a list; one of the four required Apple events.
- open file
- A file with an access path. You can read from and write to open files only.
- open permission
- Information about a file that indicates whether the file can be read from, written to, or both.
- open resource
- A resource of type 'open' that declares which file types your application can open as documents.
- open routine
- A device driver routine that allocates memory and initializes the driver's data structures. It may also initialize a hardware device or perform any other tasks necessary to make the driver operational. All drivers must implement an open routine.
- Open Scripting Architecture (OSA)
- A mechanism based on the Apple Event Manager and the Apple Event Registry: Standard Suites that allows users to control multiple applications by means of scripts. The scripts can be written in any scripting language that supports the OSA.
- Open Transport
- Industry-standard networking and communications software for the Mac OS. Supports using more than one networking protocol at once (for example, AppleTalk and TCP/IP), saving and modifying different networking configurations, and easy switching among configurations. Includes the AppleTalk and TCP/IP control panels.
- open-frame fill
- A shape fill that connects the points of the geometry from start point to end point (but not back to the start point again). Same as framed fill.
- operand
- A numerical value used with some transfer mode types (such as blend mode) to affect the outcome of the transfer-mode operation.
- operating system
- The software that controls and coordinates computer hardware so that programs installed or controlled by users can run efficiently and conveniently
- Operating System Event Manager
- The collection of low-level routines that manage the Operating System event queue.
- Operating System event queue
- A queue that the Operating System Event Manager creates and maintains. The Operating System Event Manager detects and reports low-level hardware-related events such as mouse clicks, keypresses, and disk insertions and places these events in the Operating System event queue.
- Operating System trap
- An exception that is caused by an A-line instruction that executes an Operating System routine.
- Operating System trap dispatch table
- A table in RAM containing addresses of Operating System routines.
- operating-system event
- An event returned by the Event Manager to communicate information about changes in the operating status of applications (suspend and resume events) and to report that the user has moved the mouse outside of an area specified by the application (mouse-moved events)
- operating-system queue
- A queue used by the Mac OS.
- operation code
- The part of a machine instruction that encodes the operation to be performed. Often shortened to opcode.
- optional parameter
- A supplemental parameter in an Apple event used to specify data that the server application can use in addition to the data specified in the direct parameter. Source applications list the keywords for parameters that they consider optional in the attribute identified by the keyOptionalKeywordAttr keyword. Target applications use this attribute to identify any parameters that they are required to understand. If a parameter's keyword is not listed in this attribute, the target application must understand that parameter to handle the event successfully
See also: Apple event attribute, Apple event parameter
- original application heap zone
See: application heap zone
- original recipient
- Any of four specific types of recipient that can be specified by the sender of a message: To, From, cc, or bcc. An original recipient may be a group address. A non-letter message can include only From and To recipients
See also: resolved recipient
- OR mode
- A transfer mode type in which the bits of the source color component and destination color component are combined using an OR operation.
- OSA
See: Open Scripting Architecture (OSA)
- outgoing message
- A message that is leaving an AOCE system to go to an external messaging system.
- outgoing queue
- A queue from which an MSAM reads messages that it must deliver to an external messaging system.
- outline font
- A font made up of outline glyphs in a particular typeface and style, with no size restriction. The Font Manager can generate thousands of point sizes from the same outline font.
- outline highlighting
- The highlighting of a selection range by drawing an outline around the selected characters. Typically used to show a selection range in an inactive window.
- outline point
- A point used by the Font Manager to calculate the lines and curves that constitute an outline glyph
See also: on-curve point, off-curve point
- output printer
- The printer to which a document is sent to be printed. If the document's formatting printer is different than the output printer, the print file reflects the output printer's formatting; however, the document itself retains its original format
See also: formatting printer
- out of gamut
- Said of a color that cannot be represented on a given device.
- oval
- A circular or elliptical shape defined by the bounding rectangle that encloses it. The oval is completely enclosed within the infinitely thin lines of its bounding rectangle, and never includes any pixels lying outside the bounding rectangle. If the bounding rectangle is square (that is, has equal width and height), then the oval is a circle.
- overflow exception
- A floating-point exception that occurs when the magnitude of a floating-point result is greater than the largest finite number that the destination data format can represent.
- overflow notice
- A QuickDraw GX notice indicating that a notice could not be added to the ignore notice stack because the implementation limit had been exceeded
See also: implementation limit
- overflow warning
- A QuickDraw GX warning indicating that a warning could not be added to the ignore warning stack because the implementation limit had been exceeded
See also: implementation limit
- override
- To intercept a message and take action on it
See also: message override, override function
- override function
- The code, defined in a message handler, that responds to a message
See also: message override
- overriding ink object
- An optional part of a picture item. If a picture item has an overriding ink object, QuickDraw GX uses the information in the overriding ink when drawing the item, rather than the information in the original ink object.
- overriding style object
- An optional part of a picture item. If a picture item has an overriding style object, QuickDraw GX uses the information in the overriding style when drawing the item, rather than the information in the original style object.
- overriding transform object
- An optional part of a picture item. If a picture item has an overriding transform object, QuickDraw GX uses the information in the overriding transform when drawing the item, rather than the information in the original transform object.
- over mode
- A transfer mode type in which the source color is copied to the destination, and the source transparency controls where the destination color shows through.
- owner
- A variable, structure, or QuickDraw GX object that references an object. Many objects can be referenced by more than one variable and can thus have multiple owners
See also: certificate owner
- owner count
See: reference count