Reducing information transfer in screen capture series

• US 20040222995A1
• Filed: 05/30/2002
• Published: 11/11/2004
• Est. Priority Date: 05/30/2002
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Colle, Olivier
• Granted Patent: US 7,447,997 B2
• Time in Patent Office: Days
• US Class Current: 345/545
• CPC Class Codes: G09G 2360/127 Updating a frame memory using a transfer of data from a source area to a destination area
• CPC Class Codes: G09G 5/36 characterised by the display of a graphic pattern, e.g. using an all-points-addressable [APA] memory

Abstract

A screen capture tool reduces information transfer when capturing a series of screen areas. For example, the screen capture tool reduces usage of Bit Block Transfer operations from a display card frame buffer to system memory. The screen capture tool scans pixel values in portions of a screen area to detect changes relative to a previously captured screen area, identifying portions to be updated by BitBlt operation. Or, the screen capture tool analyzes display driver commands to identify portions of a screen area to be updated by BitBlt operation. The screen capture tool then constructs a representation of the screen area. For example, the screen capture tool provides portions of the screen area that do not require a BitBlt operation (which may involve copying or other use of pixel information already in system memory) and then captures other portions of the screen area by BitBlt operation.

Claims

1. A computer-readable medium storing computer-executable instructions for causing a computer system programmed thereby to perform a method of capturing a screen area of a visual display unit, the method comprising:

based upon analysis of one or more display driver commands, determining for each of one or more regions of the screen area whether to provide the region with or without bit block transfers from a display card frame buffer; and

constructing a representation of the screen area in system memory.

2. The computer-readable medium of claim 1 wherein the constructing includes capturing all of the screen area by bit block transfer from a display card frame buffer.

3. The computer-readable medium of claim 1 wherein the constructing includes providing all of the representation of the screen area without bit block transfers from a display card frame buffer for the screen area.

4. The computer-readable medium of claim 3 wherein the providing comprises using pre-determined screen feature pixel information.

5. The computer-readable medium of claim 3 wherein the providing comprises copying a previous screen area representation in the system memory.

6. The computer-readable medium of claim 1 wherein the constructing includes providing at least some of the representation of the screen area without bit block transfers from a display card frame buffer and capturing at least some of the screen area by bit block transfer from the display card frame buffer.

7. The computer-readable medium of claim 6 wherein the providing comprises copying a previous screen area representation in the system memory and moving one or more regions of the copied previous screen area representation.

8. The computer-readable medium of claim 1 wherein the method further comprises:

capturing a first screen area in a series by bit block transfer from a display card frame buffer; and

for each of at least one subsequent screen area in the series, performing the determining and the constructing.

9. The computer-readable medium of claim 1 wherein the analysis indicates one or more operations specifying cursor placement or shape for the screen area.

10. The computer-readable medium of claim 1 wherein the analysis indicates one or more operations specifying movement of previous screen area pixel information for the screen area.

11. The computer-readable medium of claim 1 wherein the screen area shows an entire screen, a window, or a user-specified area.

12. A computer-readable medium storing computer-executable instructions for causing a computer system programmed thereby to perform a method of capturing a screen area of a visual display unit, the method comprising:

at each of one or more pixel locations in the screen area,

comparing a pixel value to an expected value;

when no change is detected, designating a block of the screen area including the pixel location to be provided without bit block transfers; and

constructing a representation of the screen area in system memory

13. The computer-readable medium of claim 12 wherein the constructing includes capturing all of the screen area by bit block transfer from a display card frame buffer.

14. The computer-readable medium of claim 12 wherein the constructing includes providing all of the representation of the screen area without bit block transfers from a display card frame buffer for the screen area.

15. The computer-readable medium of claim 14 wherein the providing comprises copying a previous screen area representation in the system memory.

16. The computer-readable medium of claim 12 wherein the constructing includes providing at least some of the representation of the screen area without bit block transfers from a display card frame buffer and capturing at least some of the screen area by bit block transfer from the display card frame buffer.

17. The computer-readable medium of claim 12 wherein the method further comprises:

capturing a first screen area in a series by bit block transfer from a display card frame buffer; and

for each of at least one subsequent screen area in the series, performing the comparing, the designating, and the constructing.

18. The computer-readable medium of claim 12 wherein the screen area shows an entire screen, a window, or a user-specified area.

19. The computer-readable medium of claim 12 wherein the method further comprises, before the constructing, joining one or more blocks designated to be provided without bit block transfers with one or more blocks designated to be captured by bit block transfer to improve bit block transfer efficiency.

20. In a screen capture tool, a method comprising:

based upon analysis of one or more display driver commands, identifying any portions of a screen area to capture by transfer of pixel information from a display card frame buffer; and

transferring the pixel information from the display card frame buffer for the identified portions.

21. The method of claim 20 wherein the analysis includes converting the one or more display driver commands to one or more screen capture operations.

22. The method of claim 21 wherein the analysis further includes simplifying a list of the one or more screen capture operations to reduce the number of screen capture operations while also reducing transfers from the display card frame buffer.

23. The method of claim 21 wherein at least one screen capture operation specifies movement of pixel information of a base captured screen area in system memory for the captured screen area.

24. The method of claim 21 wherein at least one screen capture operation specifies cursor position or cursor shape.

25. The method of claim 21 wherein at least one screen capture operation specifies text display.

26. The method of claim 21 wherein at least one screen capture operation specifies a bitmap to transfer from the display card frame buffer.

27. A computer-readable medium storing computer-executable instructions for causing a computer system programmed thereby to perform the method of claim 20.

28. In a screen capture tool, a method comprising:

scanning pixel values in a display card frame buffer for a screen area to identify pixel value changes in portions of the screen area; and

transferring pixel information from the display card frame buffer for the portions of the screen area in which pixel value changes are identified.

29. The method of claim 28 wherein one pixel value in each of the portions of the screen area is scanned.

30. The method of claim 28 further comprising adaptively changing configuration of the portions.

31. The method of claim 28 further comprising changing locations within the portions for the scanning.

32. A computer-readable medium storing computer-executable instructions for causing a computer system programmed thereby to perform a method of claim 28.

33. A computer system comprising:

a display card;

a processor;

system memory; and

a screen capture tool for retrieving from the display card pixel information for screen areas based upon analysis of display driver commands.

34. The computer system of claim 33 wherein the screen capture tool converts the display driver commands into a list of screen capture operations, and wherein the screen capture tool simplifies the list to reduce bit block transfer usage.

35. The computer system of claim 33 wherein the analysis indicates base screen area pixel information in the system memory for the screen capture tool to move for a current screen area.

36. The computer system of claim 33 wherein the analysis indicates cursor information for the screen capture tool to use in a current screen area.