Sun Microsystems, Inc.

Jerald R Evans

James A Graham

Susan Elizabeth Carrie

Serdar Ergene

Sheue-Ling Lien

James Van Loo

Michael J Shantz

Thanh Nguyen

Jeannette Hung

Paolo Enrique Sabella

Deron D Johnson

Jeffrey Spirn

Vaughan R Pratt

John L Fetter

The present invention provides a method and apparatus that permits the introduction of customized compositing techniques into an application by a developer. A Composite interface and a CompositeContext interface are defined. Custom compositing operations can be defined by implementing these interfaces. A Composite object provides a CompositeContext object that holds the state and performs the compositing work. Multiple CompositeContext objects can be created from one Composite object to maintain separate states in a multi-threaded environment. An object implementing the Composite interface can be set as rendering state on a graphics object that provides rendering methods. This allows arbitrary compositing rules to be used by a developer. In one implementation of the Composite and CompositeContext interfaces, an AlphaComposite class is defined. The AlphaComposite class implements common compositing rules, such as defined by Porter and Duff, for combining source and destination pixels to achieve blending and transparency effects with graphics and images.

Method and apparatus for pixel composition

The invention provides a method and apparatus for customizing and substituting strokes provided by a standard API. In a preferred embodiment, a stroke interface that encapsulates stroking algorithms and interfaces for stroke calculation is provided by an API. The stroke interface is provided in the form of a class. The use of the stroke interface permits additional algorithms and interfaces to be provided as new classes. This allows developers to customize stroke characteristics and attributes. In a preferred embodiment, a basic stroke class contains standard stroke characteristics of a logical pen. These characteristics include line width, end cap shape, line join style, and dash attributes.

Method and apparatus for stroke substitution

Raw image data is separated from color image data such that image data can be operated on independent of a color model. Alternatively, image data can be associated with a color model and image processing operations can operate on the image data in terms of the color model. No color model is presupposed for a given image. When an image processing operation uses a color system, a color system can be selected in which the operation is performed and the source image will be converted. Different color systems can be associated with the same image data to process the image. Where it is not necessary to perform an image processing operation in a color system, the operation can access the image data independent of a color system. In an embodiment of the invention, a Tile object class is comprised of an array of Channel objects. A Channel object is associated with one or more storage bands of image data. A ColorModel object class identifies a color system and specifies a mapping between the raw image data and the color and alpha components of a color system. A BufferedImage object class is defined that associates a ColorModel with a Tile. BufferedImageOp and TileOp interfaces are defined in embodiments of the invention that are implemented by image processing or filtering object classes. A BufferedImageOp interface is used for filtering operations performed within a color system. Filtering operations that are performed outside a color system use the TileOp interface.

Method and apparatus for separating image data from a color system in image processing

A method and apparatus for handling alpha premultiplication is described. In an embodiment, image data is contained within an instance of an image object that also contains a state variable indicating whether the image data is currently premultiplied or non-premultiplied. A method within the image object responds to requests to coerce the image data into a desired or destination premultiplication state. Based on the value of the state variable, the method multiplies or divides the image data components by the alpha component, or does nothing. The state variable is updated to reflect any change in the premultiplication state of the image data. In one embodiment, the image object is implemented as a buffered image object instance containing a tile object instance and a color model object instance. The tile object instance maintains a reference to a data array(s) containing the image data file, and provides methods for inserting and extracting pixel data from the data array(s). The color model object instance contains the premultiplication state variable for the image data, and a method for coercing the image data into a desired premultiplication state. Applications can insure that image data is in the desired premultiplication state by accessing the associated buffered image object instance to invoke the coercion method, and specifying the desired state. The buffered image object instance responds by invoking the data coercion method in the color model object instance, and specifying the desired premultiplication state and the tile object instance containing the image data.

Method and apparatus for handling alpha premultiplication of image data

In a bit mapped display environment which has n hardware color look-up tables (CLUTs) where n=1 or more, which also has a limited number of Display Attribute Identification Values, and which may operate under various window systems, such as the X Window System protocol, an apparatus and a method for installing and uninstalling hardware colormaps under the constraint of a finite number of Display Attribute Identification Values, whereby the most recently installed (MRI) policy of the X Window System is followed. The invention provides a scheme which gracefully degenerates to some 'color flashing' when Display Attribute Identification Values are exhausted; which allows Display Attribute Identification Values to be uncoupled from colormap management and used for more graphics intensive functions when needed; and which dynamically regenerates when display attributes again become available. The invention also minimizes the rendering of the Display Attribute Planes when a new colormap is installed in a system containing multiple hardware color look-up tables.

Apparatus and method for managing the assignment of display attribute

An adaptive forward differencing apparatus, wherein, when rendering curves, calculated x, y values are increased or decreased in order to create values which correspond to the next pixel of the display CRT, such that curves of substantially one pixel increments are continuously and uniformly generated. The apparatus also provides circuitry for generating coordinates of display elements which approximate an ideal vector and to define curves, vectors or objects within maximum and minimum coordinates of the CRT display. The apparatus also provides efficient circuitry for computing the value of 1/w of the homogenous coordinate w.

Method and apparatus for deriving instantaneous reciprocals of the

An adaptive forward differencing apparatus wherein, when rendering curves, calculated x, y values are increased or decreased in order to create values which correspond to the next pixel of the display CRT, such that curves of substantially one pixel increments are continuously and uniformly generated. The apparatus also provides circuitry for generating coordinates of display elements which approximate an ideal vector and to define curves, vectors or objects within maximum and minimum coordinates of the CRT display. The present invention also provides efficient circuitry for computing the value of 1/w of the homogenous coordinate w.

Method and apparatus for adaptive forward differencing in the rendering

The system of the present invention provides for the flow control of commands to devices connected through the system's memory management unit and is particularly useful in a multi-tasking computer system in which multiple processes access the same device. In the method and apparatus of the present invention, devices that are connected to the system through the MMU are controlled using the page fault mechanism of the MMU and the page fault handler in each segment. Addresses are allocated in the process address space for each process to provide for the addressing of the devices and device queues connected through the MMU, such that one device or one device queue is mapped into one segment of each process address space that will access the device. The 'valid bits' associated with each page in a segment are turned on/off by the process or operating system in order to control the device. If the valid bits are off or reset and an attempt is made to access at the address, a page fault occurs and the page fault mechanism invokes the page fault handler of the corresponding segment. The page fault mechanism of the MMU and the page fault handler of each segment are then utilized to determine the reason the page fault occurred with respect to a particular process and perform predetermining steps to control the flow of commands to the device.

Method and apparatus for the flow control of devices

The system of the present invention provides for the synchronization of access devices connected through the system's memory management unit and is particularly useful in a multi-tasking computer system in which multiple processes access the same device. In the method and apparatus of the present invention, devices that are connected to the system through the MMU are controlled using the page fault mechanism of the MMU and the page fault handler in each segment. Addresses are allocated in the process address space for each process to provide for the addressing of the devices and device queues connected through the MMU, such that one device or one device queue is mapped into one segment of each process address space that will access the device. The 'valid bits' associated with each page in a segment are turned on/off by the process or operating system in order to control the device. If the valid bits are off and an attempt is made to access at the address a page fault occurs and the page fault mechanism invokes the page fault handler of the corresponding segment. The page fault mechanism of the MMU and the page fault handler of each segment are then utilized to determine the reason the page fault occurred with respect to a particular process and to perform steps to synchronize access to the device.

Method and apparatus for the synchronization of devices

An adaptive forward differencing apparatus wherein, when rendering curves, calculated x, y values are increased or decreased in order to create values which correspond to the next pixel of the display CRT, such that curves of substantially one pixel increments are continuously and uniformly generated. The apparatus of the present invention also provides circuitry for generating coordinates of display elements which approximate an ideal vector and to define curves, vectors or objects within maximum and minimum coordinates of the CRT display. The present invention also provides efficient circuitry for computing the value of 1/w of the homogenous coordinate w.

Method and apparatus for rendering vectors using bresenham parameters

The present invention provides apparatus and methods which are most advantageously used in conjunction with a computer display system incorporating the use of a Z-buffer to provide three dimensional hidden surface elimination. A buffer memory is provided which is sufficiently large such that each display element (pixel) on the display is represented by a 16-bit Z value. The Z value corresponds to the Z axis depth of the object at the particular point corresponding to the pixel. The buffer comprises a plurality of dynamic random access memories (D-RAMs) having two operation modes: Normal and Read-Modify-Write (RMW). A counter/pointer register is provided which successively addresses values in the buffer representing successive pixels along scan lines of the display. A graphics processor is provided with coordinates defining a three dimensional image to be displayed and, for each point of the object, computes a current Z.sub.c value beginning at an initial coordinate address in memory. The initial address is loaded into the graphics processor and a D-RAM read-modify write (RMW) cycle is initiated concurrent with the calculation of Z.sub.c. This address corresponds to the address for the point at which the graphics processor is computing Z.sub.c. The value of Z.sub.p, the prior Z value for that address location, is read from the buffer memory and stored in a data-out register. The dynamic RAM in the buffer then waits in the RMW cycle until the processor fetches the Z.sub.p value from the data-out register and compares it to Z.sub.c. The value of Z.sub.p in the buffer is updated if Z.sub.c is less than Z.sub.p. If Z.sub.c is greater than or equal to the Z.sub.p the RMW cycle is aborted, and the current value of Z.sub.p in the buffer is maintained.

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Mountain View, CA, United States of America

Jerald R Evans