The present invention relates to a document processing apparatus and, more particularly, to improvements in its editing function with regard to tabulation, paragraph indent, centering, right margin flush and so forth.
The document processing apparatus generally called "word processor" is so designed as to input a document while visually representing the input data on a display, and it is provided with a variety of editing functions for production of document.
Out of such editing functions, a tab function is used for arranging a character or symbol at a predetermined tab position on a display as required per line; a paragraph indent function is used for arranging the top of a paragraph of plural lines at a tab position; and a right margin flush function is used for arranging the end of each line of characters and symbols at a right margin position as required per line.
FIG. 10 (A) illustrates data represented visually on a display with the top of a paragraph of plural lines arranged at a tab position by the paragraph indent function in a conventional word processor, wherein there are shown a left margin 10, a right margin 11, a tab mark 12, and a control code mark 15 for paragraph indent. In the case of displaying a control code mark 15 as in FIG. 10 (A), code data corresponding to the mark to be represented visually on the display is stored in an input data buffer incorporated in a RAM (random access memory) of a controller. It is also customary to execute control of tabulation and right margin flush functions.
FIG. 11 shows the screen of a display where the top of a row of characters is set at a tab position by a tab function in a conventional apparatus, in which a control code mark denoting the tab function is not represented, and space codes 14 are existent in a region extending from a left margin 10 to a tab position denoted by a tab mark 12. Actually, however, the space codes 14 are not displayed visually on the screen. In the case of FIG. 11, the space codes 14 corresponding to the data to be displayed and the character code for ABCDE are also stored in the input data buffer. Such control is similarly executed with respect to functions of paragraph indent and right margin flush as well.
When a character such as "X" is input by superposition on the control code mark 15 after the document is edited by the paragraph indent function as shown in FIG. 10 (A), the control code data is replaced in the input data buffer with code data of the character "X", so that the code data representing the paragraph indent is erased with respect to the 1st line and consequently the paragraph indent function is canceled at the moment of inputting the code data of the character "X" as shown in FIG. 10 (B), whereby the top of the character row XABCD . . . is shifted to the left margin 10 while the 2nd character row is rendered continuous with the 1st character row, and further the 3rd character row is rendered continuous with the 2nd character row to eventually bring about disorder of the format. Accordingly, for avoiding any change in the format from the 1st line though the 3rd line, it becomes necessary to perform an intricate operation which, as shown in FIG. 10 (C), inputs a plurality of space codes 14 in the 1st line from the left margin 10 to the character "X" and also in the 2nd and 3rd lines from the left margin 10 to the tab position denoted by a tab mark 12.
Besides the above, since the control code mark 15 is not displayed at all, discrimination between the presence and absence of the paragraph indent function is indistinct so that there may arise a problem of erroneous operation in readiting the document with correction and deletion of words.
In comparison therewith, when displaying space codes 14 as shown in FIG. 11 or storing them in the input buffer without displaying or storing the control code, the format is not changed by replacement of any space code 14 with character or symbol code data. However, when canceling any function such as tabulation, paragraph indent or right margin flush, a multiplicity of space codes 14 need to be erased in sequence to consequently intricate the operation.