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Rectangle in Raster Graphic Displays

IP.com Disclosure Number: IPCOM000086949D
Original Publication Date: 1976-Nov-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Male, K: AUTHOR [+2]

Abstract

Certain types of raster graphic displays display solid areas of color rather than mere outlines formed by discrete vectors. In such a display, these areas are typically represented by a vector which defines the left hand edge of the area and a set of attributes that define color and/or tone to the right of the vector to the next vector. Thus, any area requires at least two vectors. For many applications, however, this approach is wasteful of vectors and hence of time and storage capacity, especially when only areas having sides which are parallel to the horizontal and vertical axes of the screen are required.

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Rectangle in Raster Graphic Displays

Certain types of raster graphic displays display solid areas of color rather than mere outlines formed by discrete vectors. In such a display, these areas are typically represented by a vector which defines the left hand edge of the area and a set of attributes that define color and/or tone to the right of the vector to the next vector. Thus, any area requires at least two vectors. For many applications, however, this approach is wasteful of vectors and hence of time and storage capacity, especially when only areas having sides which are parallel to the horizontal and vertical axes of the screen are required.

Such areas can be uniquely defined using only one vector word to define a diagonal of the rectangle. Using a simple hardware or software implemented algorithm, the edges can be constructed parallel to the X and Y axes. Fig. 1 shows a typical vector data word. X Y are the coordinates of the start of the vector, X Y are the coordinates of the end of the vector, field T represents data type (for example, character, vector and area) and field A represents attribute information (for example, color and dotted line).

Thus, if field T were to indicate that the word represents a vector, the display system would generate a line of points extending between X(1) Y(1) and X(2) Y(2) and display these as a line. This is illustrated in Fig. 2. If, on the other hand, field T were to indicate that the word represented an area, the graphics...