Computer graphics processing and selective visual display system – Display driving control circuitry – Controlling the condition of display elements
Reexamination Certificate
1995-11-28
2004-06-15
dela Torre, Crescelle N. (Department: 2173)
Computer graphics processing and selective visual display system
Display driving control circuitry
Controlling the condition of display elements
C345S215000
Reexamination Certificate
active
06750858
ABSTRACT:
COPYRIGHT NOTIFICATION
Portions of this patent application contain materials that are subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document, or the patent disclosure, as it appears in the Patent and Trademark Office.
FIELD OF THE INVENTION
This invention generally relates to improvements in computer systems and, more particularly, to operating system software for managing window display areas in a graphic user interface.
BACKGROUND OF THE INVENTION
One of the most important aspects of a modern computing system is the interface between the human user and the machine. The earliest and most popular type of interface was text based; a user communicated with the machine by typing text characters on a keyboard and the machine communicated with the user by displaying text characters on a display screen. More recently, graphic user interfaces have become popular where the machine communicates with a user by displaying graphics, including text and pictures, on a display screen and the user communicates with the machine both by typing in textual commands and by manipulating the displayed pictures with a pointing device, such as a mouse.
Many modern computer systems operate with a graphic user interface called a window environment. In a typical window environment, the graphical display portrayed on the display screen is arranged to resemble the surface of an electronic “desktop” and each application program running on the computer is represented as one or more electronic “paper sheets” displayed in rectangular regions of the screen called “windows”.
Each window region generally displays information which is generated by the associated application program and there may be several window regions simultaneously present on the desktop, each representing information generated by a different application program. An application program presents information to the user through each window by drawing or “painting” images, graphics or text within the window region. The user, in turn, communicates with the application by “pointing at” objects in the window region with a cursor which is controlled by a pointing device and manipulating or moving the objects and also by typing information into the keyboard. The window regions may also be moved around on the display screen and changed in size and appearance so that the user can arrange the desktop in a convenient manner.
Each of the window regions also typically includes a number of standard graphical objects such as sizing boxes, buttons and scroll bars. These features represent user interface devices that the user can point at with the cursor to select and manipulate. When the devices are selected or manipulated, the underlying application program is informed, via the window system, that the control has been manipulated by the user.
In general, the window environment described above is part of the computer operating system. The operating system also typically includes a collection of utility programs that enable the computer system to perform basic operations, such as storing and retrieving information on a disc memory and performing file operations including the creation, naming and renaming of files and, in some cases, performing diagnostic operations in order to discover or recover from malfunctions.
The last part of the computing system is the “application program” which interacts with the operating system to provide much higher level functionality, perform a specific task and provide a direct interface with the user. The application program typically makes use of operating system functions by sending out series of task commands to the operating system which then performs a requested task, for example, the application program may request that the operating system store particular information on the computer disc memory or display information on the video display.
FIG. 1
is a schematic illustration of a typical prior art computer system utilizing both an application program and an operating system. The computer system is schematically represented by dotted box
100
, the application is represented by box
102
and the operating system by box
106
. The previously-described interaction between the application program
102
and the operating system
106
is illustrated schematically by arrow
104
. This dual program system is used on many types of computer systems ranging from main frames to personal computers.
The method for handling screen displays varies from computer to computer and, in this regard,
FIG. 1
represents a prior art personal computer system. In order to provide screen displays, application program
102
generally stores information to be displayed (the storing operation is shown schematically by arrow
108
) into a screen buffer
110
. Under control of various hardware and software in the system the contents of the screen buffer
110
are read out of the buffer and provided, as indicated schematically by arrow
114
, to a display adapter
112
. The display adapter
112
contains hardware and software (sometimes in the form of firmware) which converts the information in screen buffer
110
to a form which can be used to drive the display monitor
118
which is connected to display adapter
112
by cable
116
.
The prior art configuration shown in
FIG. 1
generally works well in a system where a single application program
102
is running at any given time. This simple system works properly because the single application program
102
can write information into any area of the entire screen buffer area
110
without causing a display problem. However, if the configuration shown in
FIG. 1
is used in a computer system where more than one application program
102
can be operational at the same time (for example, a “multi-tasking” computer system) display problems can arise. More particularly, if each application program has access to the entire screen buffer
110
, in the absence of some direct communication between applications, one application may overwrite a portion of the screen buffer which is being used by another application, thereby causing the display generated by one application to be overwritten by the display generated by the other application.
Accordingly, mechanisms were developed to coordinate the operation of the application programs to ensure that each application program was confined to only a portion of the screen buffer thereby separating the other displays. This coordination became complicated in systems where windows were allowed to “overlap” on the screen display. When the screen display is arranged so that windows appear to “overlap”, a window which appears on the screen in “front” of another window covers and obscures part of the underlying window. Thus, except for the foremost window, only part of the underlying windows may be drawn on the screen and be “visible” at any given time. Further, because the windows can be moved or resized by the user, the portion of each window which is visible changes as other windows are moved or resized. Thus, the portion of the screen buffer which is assigned to each application window also changes as windows from other applications are moved or resized.
In order to efficiently manage the changes to the screen buffer necessary to accommodate rapid screen changes caused by moving or resizing windows, the prior art computer arrangement shown in
FIG. 1
was modified as shown in FIG.
2
. In this new arrangement computer system
200
is controlled by one or more application programs, of which programs
202
and
216
are shown, which programs may be running simultaneously in the computer system. Each of the programs interfaces with the operating system
204
as illustrated schematically by arrows
206
and
220
. However, in order to display information on the display screen, application programs
202
and
216
send display information to a central window manager program
218
located in the operating system
204
. The window manager program
218
, in turn, interfaces directly with the screen buf
dela Torre Crescelle N.
Kudirka & Jobse LLP
Object Technology Licensing Corporation
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