G
- gain
- The ratio of the output volume to the input volume
- gamut
- The range of color that a device can produce, also referred to as the device's color gamut.
- garbage data
- A type of data in a dictionary that exists if the size of the information associated with a key increases or decreases or if the information is deleted. This data is no longer used by the dictionary.
- GB
See: gigabyte (GB)
- GDevice record
- A data structure of type GDevice that holds information about the physical characteristics of a video device or offscreen graphics world, including a pixel map that describes the pixel depth for that video device or offscreen graphics world, information about whether the video device or offscreen graphics world supports indexed or direct colors, and"for indexed devices"specifications for the colors that are currently available for the video device or offscreen graphics world. System software allocates and initializes one GDevice record for each installed video device and stores the record in the system's device list.
- general purpose color-matching function
- One that uses a color world to characterize how to perform color-matching
See also: QuickDraw-specific color-matching function
- generation time
- The time during which executable code is created from source code using such program development tools as a compiler and linker
- generic scripting component
- A special scripting component that establishes connections dynamically with the appropriate scripting component for each script that a client application attempts to manipulate or execute. The generic scripting component also provides routines that you can use to determine which scripting component created a particular script, get an instance of a specific scripting component, and perform other useful tasks when you are using multiple scripting components
See also: scripting component
- generic script ID
- Special script IDs used by the generic scripting component to keep track of script IDs provided by multiple scripting components. The generic scripting component translates generic scripting IDs into the corresponding component-specific script IDs and vice versa when necessary.
- generic storage descriptor record
- A descriptor record of type kOSAGenericStorage that can be used by the generic scripting component or any other scripting component to store script data. The script data in a generic storage descriptor record is followed by a trailer that contains the subtype for the scripting component that created the script data.
- genlock
- A circuit that locks the frequency of an internal clock to an external timing source. This term is used to refer to the ability of a video digitizer to rely on external clocking.
- geometric operations
- Mathematical operations on the geometries of shape objects
See also: constructive geometry
- geometric pen
- The pen used by QuickDraw GX to draw framed shapes. The width and placement of this pen are affected by style properties.
- geometric point
- An (x, y) coordinate pair used to specify a location in a shape's geometry. Geometric points can specify the ends of lines or curves or the off-curve control points used to control curvature.
- geometric shape
- Any QuickDraw GX shape that has one of the following shape types: empty, full, point, line, curve, rectangle, polygon, path.
- geometry
- A property of a QuickDraw GX shape object. A shape's geometry is the specification of the actual size, position, and form of the shape. For example, for a line shape, the geometry specifies the locations (in local coordinates) of the end points of the line.
- geometry coordinates
- Paired values that specify a size or location in geometry space.
- geometry index
- A number used to specify a particular geometric point in a geometry: the first geometric point in a geometry has geometry index 1, and so on. Whereas contour indices start over with each contour in a geometry, geometry indices do not.
- geometry space
- The coordinate system represented by the geometry of a shape object
See also: device space, global space, local space
- Gestalt Manager
- The part of the Mac OS that you can use to determine the features of the current software and hardware operating environment.
- ghost indicator
- A transparent outline image of a track's indicator. The ghost indicator tracks the movement of the pointer while the user holds the mouse button.
- gigabyte (GB)
- 1024 megabytes, or 1,073,741,824 bytes.
- global controls
- Controls, such as push buttons, which affect all panes of a multi-pane window, not just the active pane
See also: pane
- global coordinates
- (1) Paired values that specify a size or location in global space. (2) For QuickDraw GX, the coordinate system used for a view group. For example, a view port's location is described in global coordinates. This coordinate system represents all potential drawing space. The origin, point (0,0), of the global coordinate system is located at the upper-left corner of the main screen. The positive x-axis extends to the right. The positive y-axis extends downward.
- global coordinate system
- The coordinate system that represents all potential QuickDraw drawing space. The origin of the global coordinate system"that is, the point (0,0)"is at the upper-left corner of the main screen
See also: local coordinate system
- global instantiation
- The method of allocating an import library's static data in which only one copy of that data is created regardless of how many connections to the library are made
See also: per-context instantiation, per-load instantiation
- global space
- The coordinate system, used by a view group, resulting from the application of the view port mapping shape dimensions measured in local space. A view port's location, for example, is described in global coordinates
See also: device space, geometry space, local space
- global variable
- A named storage location for a modifiable value that can be referenced outside the local scope of statements using that variable. See application global variables, QuickDraw global variables, system global variables.
- global width table
- A data structure used by the Font Manager to communicate character widths to QuickDraw.
- glue routine
- A run-time library routine, usually provided by the development environment, that provides a linkage between high-level language code and a system routine with an interface protocol different from that of the high-level language. Also, any short special-purpose assembly-language routine.
- glyph
- The distinct visual representation of a character in a form that a screen or printer can display. A glyph may represent one character (the lowercase a), more than one character (the fi ligature), part of a character (the dot over an i), or a nonprinting character (the space character)
See also: character
- glyph code
- A number that specifies a particular glyph in a font. Fonts map character codes to glyph codes, which in turn specify individual glyphs.
- glyph direction
- The direction in which successive glyphs are read
See also: dominant direction
- glyph ductility
- The ability to stretch the actual form of a glyph during justification.
- glyph index
- (1) A number that specifies a particular glyph in a font. Some fonts directly specify glyphs with character codes, whereas others map character codes to glyph indexes, which in turn specify the glyphs. (2) The order of a glyph in a line of display text. The leftmost glyph in a line of text has a glyph index of 1; each succeeding glyph to the right has an index one greater than the previous glyph
See also: edge offset, glyph code
- glyph justification overrides array
- A style object property used only by layout shapes. It is an array that redefines the justification priorities and behaviors for individual glyphs.
- glyph origin
- (1) The point on a baseline used as a reference location for drawing a glyph. QuickDraw draws a glyph so that the glyph origin corresponds to the current pen position. (2) The point that QuickDraw GX uses to position a glyph when drawing.
- glyph shape
- A typographic shape that allows you to vary the position, font, rotation, and scale of each glyph in a line of text
See also: layout shape, text shape, typographic shape
- glyph substitutions array
- A style object property used only by layout shapes. It is an array specifying substitute glyphs for those that would normally be displayed in a style run.
- good-bye message
- A message sent by the Operating System to notify device drivers when an application quits or the system shuts down. To receive a good-bye message, drivers must set the dNeedGoodBye bit in the drvrFlags word.
- gradual underflow
- A process that occurs on a computer system that includes denormalized numbers.
- GraphicsBug
- A tool for debugging QuickDraw GX applications; its mode of use and command set are analogous to those of MacsBug.
- graphics client
- A region of memory where bookkeeping data is stored for a graphics client heap. This includes the memory starting address, the size and location of all of the heap's memory blocks, and the error, warning, and notice state
See also: graphics client heap
- graphics client heap
- A region of memory that contains all of the objects that a QuickDraw GX application creates. A heap that consists of public objects, such as shapes, styles, inks, and transforms, as well as private objects used for heap management
See also: application heap, graphics client, heap
- graphics device
- Anything into which QuickDraw can draw. There are three types of graphics devices: video devices (such as plug-in video cards and built-in video interfaces) that control screens, offscreen graphics worlds (which allow your application to build complex images off the screen before displaying them), and printing graphics ports. For a video device or an offscreen graphics world, Color QuickDraw stores state information in a GDevice record.
- graphics pen
- A metaphorical device for performing drawing operations onscreen. Your application can set this pen to different sizes, patterns, and colors.
- graphics port
- A complete, individual drawing environment with an independent coordinate system. Each window contains a graphics port.
- grayscale
- Consisting entirely of shades of gray.
- gray area
- The area within a scroll bar, excluding the scroll arrows and the scroll box. When the user clicks the gray area of a scroll bar, the application moves the displayed area of the document by an entire window less one line (or column, row, or character).
- gray region
- The region that represents all available desktop area"that is, a collection of rounded rectangles representing the display areas of all screens available to a computer.
- gray space
- A color space whose single component is the lightness or brightness of a color. Same as luminance color space.
- greeked
- Said of text that is drawn so that its individual characters are replaced with shading or illegible marks. Text at very small point sizes is often greeked when drawn to the screen.
- Gregorian calendar
- The calendar used in Europe and America. It is not universally accepted"for example, different calendar systems are often used in Japan, China, and the Middle East.
- grid point
- (1) A location in the QuickDraw GX coordinate system. Grid points are infinitely thin, and fall between pixels. (2) The distance between two grid points.
- group box
- A rectangular frame that may or may not contain a title. It is used to provide a well-defined area into which text, pictures, icons or other controls can be placed.
- grow image
- An outline of a window's potential new frame, drawn on the screen while the user is resizing the window with the size box.
- grow limit
- The maximum amount by which glyphs of a given priority can be extended during justification, before processing passes to glyphs of lower priority
See also: shrink limit
- grow-zone function
- A function supplied by the application program to help the Memory Manager create free space within a heap.
- guest
- A user who is logged on to a file server without a registered user name and password.
- gxColorValue
- A 16-bit unsigned integer. A fixed-point number that ranges from 0 to 65,535 to represent the numbers 0 to 1. The integer must be divided by 65,535 to obtain the real number represented. The color value number for 1.0 is 0xFFFF.