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Description  |
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FIELD OF THE INVENTION
The invention relates to a graphics display tool with a graphics processor
for creating images, image memory for storing the images and display means
for displaying the images.
BACKGROUND ART
An article in the IBM Technical Disclosure Bulletin, vol 27, no 10A, March
1985, pp 5496, entitled "Display named objects within a document" teaches
a real-time multiple data editor which provides for the integration of all
data on a single page in a dynamic editable form. The page may contain
both text and non-text object sets such as images, graphics, tables,
annotations and handwriting. The user may manipulate these object sets on
a page. Each object set is assigned a user-specified name and can be
recalled at anytime.
The Multiple Icon Viewing Design Tool (MIDVT) is described in an article of
the same name in the IBM Technical Disclosure Bulletin, vol 33, no 10B,
March 1991, pp 477-478. It is designed to work with the Microsoft Icon
Editor and allows users to i) select and simultaneously display a number
of icons on a single screen, ii) arrange and move the icon images anywhere
within the screen, iii) present the icons with or without their title, iv)
change, modify or eliminate their title, v) adjust the background color of
the window on which the icon is displayed and vi) expand the size of the
icon.
In the article "Homogeneous Presentation Graphics and Bit Image
Integration" in the IBM Technical Disclosure Bulletin, vol 31, no 10,
March 1989, pp 345-346, a system for integrating graphics objects and bit
images is disclosed. This is achieved by defining an empty or null segment
in order to reserve a position for the bit image.
European Patent Application EP-A-0 243 228 (PUBLIGRAFA) discloses a system
for the creation of images for publicity documents. The system
incorporates a video image reader and a graphic console with keyboard,
graphic tablet and a monitor to receive, combine and modify image signals
and colors. A computer is used to combine the video and vectorial image
signals and creates one picture or a series of pictures simulating a
product wrapper.
European Patent Application EP-A-0 352 012 (IBM) discloses a system for
displaying graphics images on a display device. The system comprises a
memory for storing graphics images represented by a plurality of picture
elements. The memory is divided into a plurality of memory buffers and the
graphics images can be either stored in a plurality of memory buffers or
in successive positions in one of the memory buffers. Image mixing means
combine the required picture elements for display.
Similarly U.S. patent U.S. Pat. No. 4,392,130 (ASEA) teaches a method for
presenting graphical information in the form of an image in which the
image is assembled from a plurality of symbols defined in advance.
An automatic icon generation system is described in the European Patent
Application EP-A-0 427 264 (FUJITSU). The system comprises an icon pattern
memory for memorizing, as icon patterns, a plurality of graphic elements,
an icon synthesizer for generating the icon from the icon patterns, an
icon utilization controller and a display controller for displaying the
icons.
A number of commercial products are on the market which allow a user to
create his or her own graphical displays on a display device such as a VDU
terminal. Two of the best known are incorporated into the IBM Presentation
Manager and the Microsoft Windows. Microsoft Windows provides a Paintbrush
facility which enables the user either to produce a graphical display
freehand or to combine pre-defined graphical elements, such as a square,
circle, rectangle etc. in order to produce a new image. The image can be
colored, enlarged or altered using the provided tools. The image can be
saved for later use. Full details of the operation of the Paintbrush
window are given in Chapter 8, pp 257-313 of the Microsoft Windows User's
guide for the Windows Graphical Environment, Version 3.0, published by
Microsoft Corporation, 1990.
General reference to object-oriented programming techniques can be found in
Bertrand Meyer, "Object-oriented software construction", Prentice-Hall,
London, 1988.
All of the above cited prior art has the disadvantage that for every new
application that a developer writes, the graphic display has to be
developed from first principles. That is to say, the applications
developer has to develop new display techniques out of very simple graphic
fragments. The display techniques form part of the applications program
and are permanently stored with it.
In addition, displaying complicated graphical objects and allowing users to
directly manipulate the interface requires substantial extra programming,
especially if the graphic objects may be networked together.
As graphic displays become more complicated, it is necessary to display
more and more items on the screen. This can lead to performance problems
when drawing the screens and also results in a lack of clarity of the
display.
SUMMARY OF THE INVENTION
The object of the invention is therefore to provide an improved graphics
display tool which overcomes the above problems. The invention achieves
this by allowing the user to define a graphical object containing details
of the appearance of a graphical figure. The user can then define
instances of the graphical object which can be directly manipulated within
the application that is being written.
In order to improve the performance of the graphic display, with each
instance of the graphical object a simple symbol can be associated. This
symbol can be displayed instead of the graphical figure.
The instances of the graphical objects can be linked together. These links
may be defined between instances of graphical objects in different
hierarchical level--to obtain a tree-type structure--or between graphical
objects in the same hierarchical level. On the display device, the links
may be made to be visible, such as by connecting a line between two linked
objects, or they only be noticeable when the user carries out some action,
such as zooming.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows the equipment required for implementing this invention.
FIG. 2 shows graphical layer concept according to this invention.
FIG. 3 shows an example of a figure built up from fragments and its
associated symbol.
FIG. 4A shows the data structure for a template of a graphical object.
FIG. 4B shows the data structure for an instance of the graphical object.
FIG. 5 shows the data structure for an area.
FIG. 6A shows the data structure for a template of a connection style.
FIG. 6B shows the data structure for an instance of the connection style.
FIG. 7 shows a mark on a figure.
FIG. 8 shows the data structure of a mark style.
FIG. 9 shows the data structure of a view.
FIG. 10 shows graphic objects displayed in an area with the fragments from
which the figures representing the graphic objects are built.
FIG. 11 shows an overview window in symbol display and a detail window in
fragment display.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Definitions
In order to enable a better understanding of the invention, a number of
definitions will now be given. Some of these definitions are extracted
from the brochure "Operating System/2 Version 1.2 Programming Overview.",
first edition, September 1989, published by IBM Corporation. This document
is incorporated by reference.
Graphics Presentation Spaces
The graphics presentation space is an area in which graphics pictures are
created before being sent to a display device. The graphics presentation
space also contains other information about the graphic data it holds. An
application must first define one or more graphics presentation spaces.
Each presentation space is identified with a unique handle.
Device Contexts
Each display device to which the drawing is to be sent has unique
characteristics. Those characteristics are defined in a device context.
Each window can have a device context associated with it. Each device
context is identified by a device context handle.
Metafiles
A metafile defines the contents of a picture so that it can be used by
other applications. Pictures created by an application normally are
discarded after the application is run and recreated the next time the
application is run. The metafile contains all the instructions required to
create the final version of the picture.
Bitmap
A representation in memory of the data displayed on an
all-points-addressable (APA) display device, such a a VDU screen. Bit maps
define the contents of a complete physical or logical device. A window,
for example, is a logical screen. Because bitmaps require no picture
generation before displaying their contents on the screen, their greatest
advantage is speed.
Icon
A pictorial representation of a selection choice. The icon is defined in a
bit map.
Tag
A tag is a line of text. It is most often used for appending text to a
picture. They can be surrounded by a box if required.
Geometrics
A list of co-ordinates that are connected by straight lines or splines,
thereby forming simple shapes. They can be colored. Specialized geometrics
can be used to define chords, boxes etc.
The apparatus required for implementing the invention is shown in FIG. 1.
It comprises a display device 7, normally a VDU screen, on which the
graphic displays created are to be displayed. Connected to the display
screen 7 are a keyboard 5 and a pointing device 6, normally a mouse. A
graphics processor 8 creates the graphic display on the screen in
accordance with the invention. It defines the graphics presentation space
in which the display is to be created and uses the device contexts
associated with the display device 7 to produce the display. The graphics
processor 8 is connected to another processor 10 on which the application
program using the graphic display is running and to memory 9. The memory 9
can comprise both permanent storage, such as a direct access storage
device (DASD), and/or temporary storage means, such as random access
memory (RAM). The memory 9 can be divided into smaller logical portions,
each of which can store all or part of a graphics display together with
any other information necessary for the creation of the display, such as
the device contexts. Those skilled in the art will be able to design the
memory so that it is suitable for the tasks that have to be undertaken.
For example, sufficient RAM needs to be provided to store graphics
displays or parts thereof required quickly by the graphics processor 8,
whilst enough permanent storage needs to be provided so that graphics
displays or parts thereof can be stored for use at a later date.
The location of the graphics process 8, processor 10 and memory 9 is
immaterial for the implementation of this invention. For example, in one
embodiment the graphics processor is incorporated into a workstation
together with the display device 7, keyboard 5 and pointing device 6,
whilst the processor 10 running the applications program is incorporated
into a host computer. The memory 9 is divided between host and
workstation.
In another embodiment, no distinction is made between the processor 10
running the applications program and the graphics processor 8. The single
processor carrying out both functions is incorporated into a workstation.
The overall graphical display of data in an application running on the
processor 10 can be regarded as taking place in different layers as shown
in FIG. 2. These layers may be regarded as being part of the interface
between the processor (10) running the application and the user. Four
layers are shown on this figure. Each layer uses the services provided by
the next lower layer.
The highest layer (layer 4) manages views on the display device 7 by means
of windows 12 using the layout information 14 on graphic objects found in
a third layer 3. The third layer 3 manages the layout of graphic objects
in a defined area using the graphic object display information and
parameters of a second layer 2. In the second layer 2, the composition of
more or less complex graphic objects 16 are built up using the graphic
display primitives, also called fragments, 18 of a first layer 1. The
first layer 1 is the lowest level and manages the display of graphic
display primitives 18 independent of the actual display device 7 used. It
provides an inventory of display primitives used in building more
complicated figures. The IBM Presentation Manager is one example of a
product implementing the first layer 1. It would be installed in the
graphics processor 8.
The current application is concerned with the implementation of the second
layer 2 of the graphical layer concept described in the previous
paragraph. Its principles, however, are not limited to this application
and may be more widely applied by those skilled in the art.
The method in which the graphic objects 16 in the second layer 2 are
produced will now be described. Before an application can make use of any
of the graphic objects, the appearance of the graphic objects has to be
created. This process is termed the "registration" of the graphic object
and involves the creation of a template for the graphic object which
contains details of the information required to produce the graphic
object. The template is stored in one of the divisions of the memory 9 and
is assigned a handle, which points to its location in the memory 9.
As mentioned above, in order to register the graphic object, the user
creates the template for the graphic object. This is done by defining a
figure that makes up the graphic object. The figure is constructed from
combinations of the fragments or drawing primitives supplied by the first
level 1 implementation. The fragments could be, for example, simple
geometrical figures such as lines, squares or circles, or they could be
geometrics, bitmaps, metafiles or tags. Other types of fragments are
possible. An example of a figure 36 created from a number of fragments
20-34 is shown in FIG. 3.
With each created figure 36 a symbol 50 is also created. This symbol is a
much simpler representation of the figure and is stored together with the
figure as the template for the graphical object in the memory 9. The
symbol can be either one of a number of standard symbols supplied in the
level 1 implementation or it could be similarly created from fragments.
Having registered the graphic object by creating its template, it is
necessary to create an "instance" of the object. This is required since a
user running an applications program cannot manipulate the graphic object
directly, but can only operate on an instance of it. For example, the
applications program may use the same graphic object twice but in
different contexts. So the applications program would require two
different instances of the same graphic object. The instance is also
stored in memory 9 and is pointed to by an instance handle. Using this
handle, the graphics processor 8 can call up the instance of the graphic
object when required.
The figures can be more complicated than the simple case described above.
Figures can be composed of other figures--termed respectively parent
figures and child figures. So, for example, in FIG. 3, the fragments 20
and 21 that make up the eyebrows of the face could be defined as a
separate child figure, similarly fragments 28 and 29 making up the mouth
could be another child figure. Separate templates would be constructed for
the graphic object represented by the two child figures. These templates
are also stored in memory 9. The instance for the figure 36 would thus
comprise not only references to the template of the graphic object making
up the parent figure but also to the instance handles of the two child
figures. The child figures would thus be linked to the parent figures. The
template of the graphic object making up the parent figure would contain
references to the fragments 22, 24, 26, 30, 32 and 34 but not to fragments
28 and 29 or 21 and 22.
Of course the child figures might be more complicated than this and, rather
than displaying the individual fragments from which the child figure is
constructed, the symbol representing the child figure could be displayed
together with the fragments making up the parent figure. Whether the
symbol or the individual fragments which make up the child figure are to
be displayed is discussed later.
The data structure of the template for the graphic object in the memory 9
is shown on the left hand side of FIG. 4A. It consists of a pointer to the
fragment list in which the individual fragments making up the figure are
contained and a variable which points to the symbol which represents the
figure. The fragment list is shown on the right hand side of FIG. 4A. Each
entry in the list is pointed to by the handle of the fragment. The handle
identifies the required fragment in the first layer 1 of the graphical
display. The next variable in the entry indicates the manner in which the
fragment is to be initially displayed, for example switched on or off. How
to switch the fragment on or off will be discussed below when the concept
of a mark style is introduced. The relative position indicates the
co-ordinates of the fragment in the figure. Finally the last variable in
the entry is the handle to indicate the position of the next entry of the
fragment list in the memory 9. The pointer in the last entry of the
fragment list is a special pointer which indicates the end of the list.
Fragments can be added or deleted to the graphic object merely by
selecting them and adding a new entry into the fragment list. The variable
indicating the symbol associated with the graphic object calls a routine
which replaces the figure with the symbol. The symbol is, in the preferred
embodiment, one of a number of standard symbols provided in the first
layer 1 of the graphical display. The symbol could, however, be itself
built up from fragments, albeit from a fewer number of them than in the
figure.
The data structure of an instance of the graphic object is shown in FIG.
4B. It consists of a handle to the template of the graphic object defined
in FIG. 4A and a list of the handles of the connection styles which can be
associated with the instance of the graphic object. The term "connection
style" is explained in more detail below. In addition with each instance,
child objects can be associated. The handles of these associated child
objects are given in a list which is also included in the data structure.
The data structure of the instance will also contain information regarding
the display of the individual fragments should these be altered from their
initial values given in the template of the graphic object from which the
instance is created.
The child objects are only associated with their parent objects. They have
no "existence" of their own. That is to say the child objects can only be
displayed on the display device 7 when the parent object is also displayed
(the reverse is, however, not true, a parent object can be displayed
without its child object). If an instance of the parent object is
destroyed, then the instances of the child object are also destroyed. Note
however, that destroying the instance o | | |
