Method and system for displaying a structured document

Details Method and system for displaying a structured document Method and system for displaying a structured document

1998-05-12

2001-01-16

Feild, Joseph H. (Department: 2776)

Data processing: database and file management or data structures

Database design

Data structure types

C707S793000, C707S793000

Reexamination Certificate

active

06175843

ABSTRACT:

CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of Japanese Application No. 9-318807, filed Nov. 20, 1997 in Japan, which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
The present invention relates to a method and system for displaying a structured document formed of predetermined elements, and particularly to a method and system for displaying a structured document at a high speed.
DESCRIPTION OF THE RELATED ART
A structured document formed of predetermined elements, such as a document described by the Standard Generalized Markup Language (SGML), is structured only by content and structure. The definition information regarding a style for the document, such as format and attribute information required for display, is defined and administered independently of the document content information.
To display such a structured document on a displaying apparatus, or to print the document on a printing apparatus, information about the structure of the document (“structure information”) is first analyzed and separately defined information about style definition (“style definition information”) is obtained. The style definition information depends on the analyzed structure and, once obtained, is set as display or print attribute information.
The result of such a structure analysis may be represented in a tree structure. The independently defined style definition information is often defined in relation to a set of identifiers (hereinafter referred to as “tags”) that indicate the elements of the document structure in terms of the various units of the document.
FIG. 1A
shows an example of a structured document. The structured document of
FIG. 1A
includes text content for a statement in Japanese Kanji.
FIG. 1B
shows a similar document with text content for an equivalent statement in English. The document of
FIG. 1A
is analyzed for structure and structure information having a tree structure, as shown in
FIG. 2A
, is formed. Similarly, the document shown in
FIG. 1B
is analyzed and information in the tree structure shown, in
FIG. 2B
, is formed. In the tree structures shown in both
FIGS. 1A and 2B
, each tag is disassembled into a name for the corresponding document unit, and characters within the larger units are disassembled into units of one character each. Each unit is called a “node.” In the present invention, particularly, a unit with character data is represented by the following terms: a “node having character data,” or a “character data node.”
The style definition information, related to the structure information, as shown in
FIG. 3
for the document of
FIGS. 1A and 2A
, is obtained, and set as display or print attribute information. The structured document is then displayed on an object display apparatus.
To display the structured document, the tree structure generated by the foregoing structure analysis is followed from the upper nodes to the lower nodes. When a node having character data is reached, the tag for the upper node thereof is followed inversely to obtain the attribute information required for display. That is, the operation traces the tree structure backward through the upper nodes, for the node having character data, to obtain the style definition information that is independently defined through the respective node names of the upper node tags. The style definition information is then output to the display apparatus as the attribute information for display of the document.
In the tree structure shown in
FIG. 2A
, for example, this display process follows the tree from the node
2
-
1
-
1
having the tag “memo,” to the node
2
-
1
-
2
having the tag “para,” to the node
2
-
1
-
3
having character data representing the particular Kanji character data illustrated in node
2
-
1
-
3
. Similarly, the tree structure of
FIG. 2B
is followed from the “memo” node
2
-
2
-
1
, to the “para” node
2
-
2
-
2
, to the character data node
2
-
2
-
3
having the English character data “T.”
In either case, the attribute information required for display of the character (i.e., the character at node
2
-
1
-
3
or node
2
-
2
-
3
) on the display apparatus is obtained by performing the process inversely to the nodes in the upper direction. In
FIG. 2A
, the tree is first followed back to the node
2
-
1
-
2
having the tag “para.” The corresponding style definition information, as shown in
FIG. 3
, is then obtained using the tag “para” as a key (font facename: MINCHO). This style definition information then set in a display buffer area.
The attribute information for the tag “para” is defined only as a font-type (font-facename). Therefore, the tag of the next succeeding upper node is searched next in order to obtain information about font-size and font-bold, which is then set to the display buffer area. That is, the tree of
FIG. 2A
is followed inversely up to the node
2
-
1
-
1
, having the tag “memo,” to obtain the information about font-size and font-bold which are subsequently set in the display buffer area. The attribute information set in the display buffer area is then used for actual display of the document on the display apparatus. This inverse process must be repeated each time the tree-following process reaches a node having character data.
The inverse following process is repeated as many times as the number of nodes having character data in the document tree structure of
FIG. 2A
(or FIG.
2
B). Namely, in the example of the structured document of
FIG. 2A
, the operation explained above is repeated 11 times. For the corresponding English document of
FIG. 2B
, the operation is repeated 23 times. This number of repetitions increases in proportion to the number of characters in the document. When the document information includes a large amount of character data, display of the document requires a correspondingly long amount of time.
A particular case to be considered is Computer-Aided Acquisition and Logistical Support (CALS), a paperless process for management of and transactions with documents over an electronic medium in conformity with a unified specification such as SGML. Initially, CALS was applied mainly to paperless processing of technical documents such as manuals and specifications. Recently, CALS has been applied to the entire range of industrial endeavors, including manufacturing and business activities. This expanded field of application is symbolized by revision of the regular name for CALS to “Continuous Acquisition and Lifecycle Support” and moreover to “Commerce At Light Speed.”
Accordingly, an urgent demand has developed for systems and methods with improved operational ability in processing structured documents described in conformity with a unified specification such as SGML.
SUMMARY OF THE INVENTION
It is therefore a particular object of the present invention to improve the display speed for display of structured documents.
Additional objects and advantages of the invention will be set forth in part in the description that follows and, in part, will be apparent from the description or may be learned by practice of the invention.
The present invention provides a method of performing structured document display. The method comprises a step of detecting, from structure information corresponding to a structured document, a node having a tag indicating a node name for the node. The method also includes a step of comparing at least a first portion of style definition information with at least a second portion of display attribute information when a display attribute changing flag indicates that a display attribute has been changed, the style definition information corresponding to the node name.
The method of the present invention further includes the step of replacing the second portion with the first portion in the display attribute information when the second portion and the first portion do not match. Also included in the method is a step of displaying character data for a character data node in accordance with the display attribute information when the character data node is directly a

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