A system for writing cursors on a raster scanned television screen that uses the microprocessor in a display controller to produce blocks of data defining the parameters of vectors that compose the cursor. The blocks are put in a first-in first-out memory during a vertical blanking inerval or during active picture time. Each block specifies where writing of a cursor segment is to start and stop on a horizontal scan line and it also specifies a repeat count that indicates the number of lines on which the segment is to be written. Each block contains a delta value to indicate how much, if any each segment is to be displaced left or right from line to line so vertical and angulated vertical vectors can be produced. The blocks are read out of the memory consecutively by a circuit that converts the segment start and stop data to pixel counts. Pixel counters determine the writing start and stop points. When the number of horizontal lines on which segments are written equals the repeat count, the next block is processed.
A displaying apparatus comprises a CRT capable of displaying picture elements of n rows by m columns and a VRAM (Video RAM). The VRAM comprises a CRT area having addresses of n rows by m columns identical to those of the CRT and a first and a second menu areas formed at both right and left sides of this CRT area. Display data of a formatted document is stored in the CRT area, being converted into a video signal to display an image of the formatted document by means of the CRT. To point a blank space of the formatted document, as cursor is further displayed on the CRT. When a menu display is required, the data of the required menu is stored in the first and the second menu areas, being converted into a video signal. A CPU decides the leading address of the VRAM to start the display so that the cursor and the menu are displayed simultaneously on the CRT screen. Thus, an erasure of the cursor from the CRT screen can be prevented even when the menu is displayed.
A cursor display control in a graphic display system is provided in which a storage range is provided for exclusive use for a cursor pattern and a desired shape is defined in the storage range to thereby perform a high-speed cursor movement. A display control apparatus in the graphic display system includes a memory for storing a cursor pattern, shift register for performing a shift processing in a non-display period of the cursor for positioning in the display screen, and parallel-serial converter for performing parallel to serial conversion at the display timing of the cursor, whereby the apparatus is suitable to be integrated in the form of an LSI and the cursor can be moved at a high speed on the screen.
An apparatus is disclosed for displaying arbitrary forms on a raster-scanned cathode ray tube converting the analog X and Y deflection voltages of the raster signal directly into a digital TTL level blanking signal. The circuit designer, utilizing cartesian or polar coordinates, specifies a desired shape and its location utilizing the appropriate formulas. In this manner, a number of raster cut-out circuits are readily coupled to define a desired number of arbitrary shapes on a raster scanned cathode ray tube.
Method and apparatus for generating cursors for display by a color raster graphic system. The cursors displayed can assume any one of a plurality of forms. Each cursor has predetermined boundaries and includes all pixel positions of the raster within its boundaries. One pixel position is designated as the origin of the cursor and selected ones of the pixel positions for each form of the cursor will display the cursor color and intensity. The address of the origin of a cursor and its form are designated by the graphic controller of the system. The address of the origin is compared with the addresses of the pixels produced by the raster scan logic, and, when the same, the form number and the x and y coordinates, the addresses of the pixel positions of the cursor relative to the origin thereof, are produced and applied to a read-only memory which produces cursor control signals stored at the addressed locations of the cursor memory. The cursor control signals are produced in synchronization with the scanning of pixels, the positions of which correspond to selected cursor pixel positions of the cursor and are applied to the color look-up memory of the system. Such pixel control signals cause the color look-up memory to produce color control signals which cause pixels corresponding to a selected cursor pixel positions to be displayed in the cursor color and intensity to produce a cursor having the designated form with the origin of the cursor so produced being located at the designated address of a pixel in the raster.
A user-friendly procedure for the generation and display of geometric figures on a graphics screen uses a cursor placement device such as a joy stick to both define the initial position and size of the geometrical figure. Two specific examples are described: the generation of a circle and the generation of a square or rectangle. In the first example, the cursor is first positioned to point to the center of the circle at which point a small circle is drawn. The circle is expanded in response to the pressing of a designated key by the user until the desired size is attained. In the second example, the pointing by the cursor is to the upper left corner of the square or rectangle, and the square or rectangle is then expanded in response to the user deflecting the joy stick down and to the right.
