Graphics cursor handler
First Claim
1. A method for handling a cursor during execution of a graphics drawing routine comprising the steps of:
- halting said drawing routine during a frame scan any time before a line by line scan reaches the line corresponding to the top of said cursor in screen memory;
saving the cursor-free image background of said cursor;
placing said cursor in screen memory;
setting a cursor violation region to inform said drawing routine about the location the said cursor;
proceeding with said drawing routine, while checking whether said drawing routine attempts to write to a pixel protected by said cursor violation region; and
halting said drawing routine if said drawing routine attempts to write to a pixel protected by said cursor violation region;
waiting until said scan is at the scan line corresponding to the bottom of said cursor; and
restoring said cursor-free image background.
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Accused Products
Abstract
A method for handling a cursor during a graphics drawing routine that eliminates the need to insert cursor handling code into graphics function definitions. The method coordinates the placement of the cursor in screen memory with the reading out of the scan lines containing the cursor. During this time, the cursor background is saved in offscreen memory. The cursor is protected by a cursor violation region, and drawing may continue while the cursor is in screen memory so long as the cursor violation region is not infringed, in which case drawing ceases until the cursor is read out of memory. The method prevents the cursor from flickering and maximizes the availability of screen memory to the drawing routine.
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Citations
42 Claims
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1. A method for handling a cursor during execution of a graphics drawing routine comprising the steps of:
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halting said drawing routine during a frame scan any time before a line by line scan reaches the line corresponding to the top of said cursor in screen memory; saving the cursor-free image background of said cursor; placing said cursor in screen memory; setting a cursor violation region to inform said drawing routine about the location the said cursor; proceeding with said drawing routine, while checking whether said drawing routine attempts to write to a pixel protected by said cursor violation region; and halting said drawing routine if said drawing routine attempts to write to a pixel protected by said cursor violation region; waiting until said scan is at the scan line corresponding to the bottom of said cursor; and restoring said cursor-free image background. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A cursor handling mechanism for use during execution of a graphics drawing routine on a system using a line by line scan and having a window checking routine, comprising:
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means for halting said drawing routine during a frame scan any time before the line by line scan reaches the line corresponding to the top of said cursor in screen memory; instructions for saving the cursor-free image background of said cursor; instructions for placing said cursor in screen memory; instructions for setting a cursor violation region to inform said drawing routine about the location of said cursor; instructions for proceeding with said drawing routine, while checking whether said drawing routine attempts to write to a pixel protected by said cursor violation region; means for halting said drawing routine if said drawing routine attempts to write to a pixel protected by said cursor violation region; and instructions for restoring said cursor-free image background when said current scan line is near the scan line corresponding to the bottom of said cursor; wherein said instructions and halting means are in a syntax, and are executable by a processor of said graphics system. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. A cursor handling mechanism for use during execution of a graphics drawing routine on a system using a line by line scan and having a special memory available or use as a cursor violation region, comprising:
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means for halting said drawing routine during a frame scan any time before the line by line scan reaches the line corresponding to the top of said cursor in screen memory; instructions for saving the cursor-free image background of said cursor instructions for placing said cursor in screen memory; instructions for setting a cursor violation region to inform said drawing routine about the location of said cursor; instructions for proceeding with said drawing routine, while checking whether said drawing routine attempts to write to a pixel protected by said cursor violation region; means for halting said drawing routine if said drawing routine attempts to write to a pixel protected by said cursor violation region; and instructions for restoring said cursor-free image background when said current scan line is near the scan line corresponding to the bottom of said cursor; wherein said instructions and halting means are in a syntax, and are executable by a processor of said graphics system. - View Dependent Claims (19, 20, 22, 23, 24)
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21. The cursor handling mechanism of claim 180, wherein said instructions for placing said cursor in memory execute when said scan line is on the line corresponding to the top of said cursor.
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25. A computer system for computer graphics and using a cursor comprising:
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a processor; screen memory connected to said processor and having data including a cursor-free image background where the cursor is to be; a video buffer connected to said screen memory; and a display controller connected to said screen memory and to said video buffer, wherein said processor is programmed with a drawing routine and programmed to halt said drawing routine during a frame scan, any time before the line by line scan reaches the line corresponding to the top of said cursor in said screen memory, to save the cursor-free image background of the cursor, to place data representation of the cursor in the screen memory, to determine a cursor violation region, and to permit said drawing routine to continue for so long as said drawing routine does not attempt to write to a pixel protected by said cursor violation region. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33, 34)
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35. A computer system comprising:
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a host processor; a graphics processor connected to said host processor; screen memory connected to said graphics processor; wherein said graphics processor is programmed to halt a drawing routine during a frame scan any time before a line by lien scan reaches the line corresponding to the top of said cursor in said screen memory, to save from said screen memory a cursor-free image background of a cursor and to place data representing the cursor in the screen memory, to determine a cursor violation region, and to execute said drawing routine for so long as said drawing routine does not attempt to write to a pixel protected by said cursor violation region. - View Dependent Claims (36)
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37. A method for handling a cursor during execution of a graphics drawing routine, comprising the steps of:
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setting a cursor violation region to inform said drawing routine about the location of said cursor; proceeding with said drawing routine while checking whether said drawing routine attempts to write to a pixel protected by said cursor violation region; halting said drawing routine during a frame scan if said drawing routine attempts to write to a pixel protected by said cursor violation region; and resuming said drawing routine when said frame scan is at the scan line corresponding to the bottom of said cursor. - View Dependent Claims (38, 39, 40, 41, 42)
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Specification