Image transformations on an interactive raster scan or matrix display

• US 4,688,181 A
• Filed: 04/30/1986
• Issued: 08/18/1987
• Est. Priority Date: 12/22/1982
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Cottrell, Roger L., Murphy, Alan S.
• Primary Examiner(s): Gruber, Felix D.
• Assistant Examiner(s): Dixon, Joseph L.
• Application Number:
  US06/859,845
• Time in Patent Office: 475 Days
• Field of Search: 364/518, 364/521, 340/709, 340/725, 340/731, 340/744, 340/747, 340/739, 340/724, 340/734, 358/183
• US Class Current: 345/428
• CPC Class Codes: G06F 3/04812 Interaction techniques based on cursor appearance or behaviour, e.g. being affected by the presence of displayed objects
• CPC Class Codes: G06T 11/00 2D [Two Dimensional] image generation

Abstract

An interactive raster-scanned display device has a microprocessor (1) and random access memory (3) which operate to issue instructions to a drawing engine (7) to cause it to load and erase image pel representation in an image buffer (9) in order to control display of images on, or removal of images from a display screen (8) in a conventional manner. A cursor control device (10) enables a user to interact by means of a cursor symbol with images on the screen. In order to reduce the demands imposed on the drawing engine during transformation of images over the screen, the system is configured so that transformation operations are performed using alternative images substituted for the full images. Each alternative image contains considerably less detail to be drawn and erased than the full image it replaces and therefore the operation is more likely to be performed at the rate desired by the user. Thus, complex graphics images containing many vectors are replaced during transformation by simple skeletal or outline drawings. If a large size cross-hair cursor is used for easy indentification on a screen, then this also is replaced by a small symbol whenever it is moved. At the end of the transformation operation, the full image and the large cursor are restored on the screen.

Claims

1. An interactive raster-scanned display system including a microprocessor and random-access store operable to issue control signals to a drawing engine in order to display a full image on a display screen, said engine being arranged in operation in image transformation mode repetitively to erase and redraw such an image so as to change its position and/or shape in response to real-time commands received by said microprocessor from an interactive input device, characterized in that, in order to reduce the demands imposed on the drawing engine during real-time image transformation, control means are provided in said system arranged in operation in image transformation mode to substitute for said full image required to be transformed, an alternative image representing said full image but containing less detail to be drawn, and on completion of said tranformation to replace said alternative image by said full image,

in which said control means is arranged in operation to, by and substantially upon receipt of a first command from said input device, invoke image transformation means to cause said engine to erase the full image to be transformed currently on display and thereupon to draw, incrementally transformed as required by said first command, said alternative image, said control means being further arranged in operation to, in response to receipt of subsequent commands, cause said engine repetitively to erase and redraw the alternative image with incremental transformation as required in turn by each of said subsequent commands, and

in which means are provided to form in an input queue said transformation commands from said input device and to process the queued commands in order of arrival by said microprocessor, said control means being operable by and substantially upon receipt of a subsequent transformation command before the current drawing operation of the alternative image is complete to cause said engine to erase the partially drawn alternative image and to redraw said alternative image transformed as required by the most recently received command in said queue.

2. An interactive raster-scanned display system as claimed in claim 1 in which said processor is arranged in operation to store said full and alternative images in the form of vector display lists in available allocated space in said random access store.

3. An interactive raster-scanned display system as claimed in claim 1, in which said system is arranged in operation to synchronize start of an alternative image draw operation by said engine with the start of a new frame scan of said display screen.

4. An interactive raster-scanned display system including a microprocessor and random-access store operable to issue control signals to a drawing engine in order to display an image on a display screen,

said engine being arranged in operation in transformation mode repetitively to erase and redraw such an image so as to change its position and/or shape in response to real-time commands received by said microprocessor from an interactive input device,

characterized in that, in order to reduce the demand imposed on the drawing engine during real-time image transformation, said microprocessor is arranged in operation to store said image in said random access store as a vector display list ordered for selection by said engine during a drawing operation in a predetermined sequence of vectors,

the arrangement of storage being such that those vectors at the head of the list define the general shape of the image whereas those vectors at the end of the list define details of the image, and control means are provided arranged in operation to, by and substantially upon receipt by said microprocessor of each transformation command from the input device, cause said engine to erase the image currently on display and to commence to re-draw said image from said ordered list incrementally transformed as required by said transformation command,

said control means being arranged in operation whereby the drawing operation of each re-drawn image continues until receipt of a subsequent transformation command whereupon the process is repeated.

5. An interactive raster-scanned display system as claimed in claim 4, including means for forming into a queue any multiple transformation commands from said input device received during an image processing operation by said engine and said control means being operable by and substantially upon the end of such a processing operation to cause said engine to commence to redraw said image as aforesaid transformed as required by the most recently received command in said queue.

6. An interactive raster-scanned display system as claimed in claim 5, including means by which start of an image draw operation by said engine is synchronized with the start of a new frame scan of said display screen.

7. An interactive raster-scanned display system including a microprocessor and random-access store operable to issue control signals to a drawing engine in order to display a full screen cross-hair cursor at a predetermined position on a display screen and further to display a full image of an object, the position of which on the screen is determined with reference to the position of the cursor, an input device responsive to user action to issue cursor position commands to said microprocessor effective in image transformation mode to move the cursor together with the image, or part of the image, progressively over the screen from one location to another, the movement of the cursor over the screen and the corresponding movement and/or change of shape of the image being effected by said drawing engine operating under microprocessor control repetitively to erase and redraw the cursor and the object image as required by the nature of the transformation being performed characterized in that in order to reduce the demands imposed on the drawing engine during such real-time transformation, control means are provided in said system arranged in operation to, upon and during execution of said image transformation mode to substitute for said full image to be transformed an alternative image representing said full image and for said full screen-cross-hair cursor an alternative cursor defining the same screen position as said full screen cross-hair cursor, said substitute image and substitute cursor each containing less detail to be drawn than the corresponding full image and full cursor they respectively represent, and said control means being further arranged in operation to, on completion of said transformation, replace the alternative image by said full image and said alternative cursor by said full screen cross-hair cursor.

8. An interactive raster-scanned display system as claimed in claim 7, in which said system is arranged in operation whereby said cursor position commands from said input device form an input queue and are processed in order of arrival by said microprocessor, said control means being operable by and upon receipt of a subsequent cursor position command before the current drawing operation of the alternative image and alternative cursor is complete to cause said engine to erase the partially drawn alternative image and alternative cursor and to redraw said alternative image image and alternative cursor transformed as required by the most recently received command in said queue.

9. An interactive raster-scanned display system as claimed in claim 8 including means arranged in operation to monitor the elasped time from receipt by said microprocessor of the most recent command from said input device, this arrangement being such that the current transformation is regarded as having been completed when said elapsed time exceeds a predetermined value.

10. An interactive raster-scanned display system as claimed in claim 9, in which said system is arranged in operation whereby said full and alternative images and said full screen cross hair cursor and said alternative cursor are all stored in the form of vector display lists in available allocated space in said random access store.

11. An interactive raster-scanned display system as claimed in claim 10, in which said control means includes a pointer mechanism arranged in operation to identify the location of a display list of a full image to be displayed and to identify the location of a display list of the associated alternative image upon invocation or tranformation of said full image.

12. An interactive raster-scanned display system as claimed in claim 7 including means arranged in operation to monitor the elapsed time from receipt by said microprocessor of the most recent command from said input device, the arrangement being such that the current transformation is regarded as having been completed when said elapsed time exceeds a predetermined value.

13. An interactive raster-scanned display system as claimed in claim 12, in which said system is arranged in operation whereby said full and alternative images and said full screen cross hair cursor and said alternative cursor are all stored in the form of vector display lists in available allocated space in said random access store.

14. An interactive raster-scanned display system as claimed in claim 13, in which said control means includes a pointer mechanism arranged in operation to identify the location of a display list of a full image to be displayed and to identify the location of a display list of the associated alternative image upon invocation or transformation of said full image.