Methods and apparatus for reducing perceived pen-to-ink latency on touchpad devices

Patent metadata

Field	Value
Publication number	US-9529525-B2
Application number	US-201314015958-A
Country	US
Kind code	B2
Filing date	Aug 30, 2013
Priority date	Aug 30, 2013
Publication date	Dec 27, 2016
Grant date	Dec 27, 2016

Abstract

A method for reducing line display latency on a touchpad device is disclosed. The method comprises storing information regarding a plurality of prior touch events on a touch screen of the touchpad device into an event buffer. It further comprises determining an average speed and a predicted direction of motion of a user interaction with the touch screen using the plurality of prior touch events. Next, it comprises calculating a first prediction point using the average speed, the predicted direction, and a last known touch event on the touch screen. Subsequently, it comprises applying weighted filtering on the first prediction point using a measured line curvature to determine a second prediction point. Finally, it comprises rendering a prediction line between the last known touch event on the touch screen and the second prediction point.

First claim

What is claimed is:

1. A method for reducing display latency on a touchpad device, said method comprising:
storing information regarding a plurality of prior touch events on a touch screen of said touchpad device into an event buffer;
determining an average speed and a predicted direction of motion regarding a user interaction with said touch screen using said plurality of prior touch events;
calculating a prediction point using said average speed, said predicted direction, and a last known touch event on said touch screen, wherein said calculating comprises applying weighted filtering on said prediction point using a measured line curvature, wherein said applying comprises determining said measured line curvature using said information regarding a plurality of prior touch events in said event buffer; and
rendering a prediction line between said last known touch event on said touch screen and said prediction point.

2. The method of claim 1 , wherein said information is chosen from a group consisting of: X-Y coordinates, size, pressure and timestamp.

3. The method of claim 1 wherein said applying further comprises:
adding said prediction point to a front of said event buffer; and
starting with said prediction point, iterating through each event in said event buffer to determine a weight using said measured line curvature and said information, wherein said weight is applied to said prediction point to adjust a location of said prediction point.

4. The method of claim 3 , wherein said calculating further comprises:
determining a product of said average speed, said predicted direction and a constant device dependent latency value; and
summing said product with position coordinates of said last known touch event to determine said prediction point.

5. The method of claim 1 , further comprising:
in response to receiving a new touch event, removing said prediction line and rendering a line based on detected user input.

6. The method of claim 1 , wherein said prediction line is drawn with a different screen attribute versus a line drawn based on detected user input.

7. The method of claim 1 , wherein said event buffer uses a least recently used (LRU) replacement policy.

8. A non-transitory computer-readable storage medium having stored thereon, computer executable instructions that, if executed by a computer system cause the computer system to perform a method for reducing display latency on a touchpad device, said method comprising:
storing information regarding a plurality of prior touch events on a touch screen of said touchpad device into an event buffer;
determining an average speed and a predicted direction of motion of a user interaction with said touch screen using said plurality of prior touch events;
calculating a first prediction point using said average speed, said predicted direction, and a last known touch event on said touch screen;
applying weighted filtering on said first prediction point using a measured line curvature to determine a second prediction point, wherein said applying comprises determining said measured line curvature using said information regarding a plurality of prior touch events in said event buffer; and
rendering a prediction line between said last known touch event on said touch screen and said second prediction point.

9. The computer-readable medium as described in claim 8 , wherein said information is chosen from a group consisting of: X-Y coordinates, size, pressure and timestamp.

10. The computer-readable medium as described in claim 8 , wherein said applying further comprises:
adding said first prediction point to a front of said event buffer; and
starting with said first prediction point, iterating through each event in said event buffer to determine a weight using said measured line curvature and said information, wherein said weight is applied to said first prediction point to determine said second prediction point.

11. The computer-readable medium as described in claim 8 , wherein said calculating further comprises:
determining a product of said average speed, said predicted direction and a constant device dependent latency value; and
summing said product with position coordinates of said last known touch event to determine said first prediction point.

12. The computer-readable medium as described in claim 8 , wherein said method further comprises:
in response to receiving a new touch event, removing said prediction line and rendering a line based on detected user input.

13. The computer-readable medium as described in claim 8 , wherein said prediction line is drawn with a different screen attribute versus a line drawn based on detected user input.

14. The computer-readable medium as described in claim 8 , wherein said event buffer uses a least recently used (LRU) replacement policy.

15. An apparatus to perform a method for reducing line display latency on touchpad devices, said apparatus comprising:
a body;
a bus;
a touch screen display, wherein said touch screen display is operable to receive a user input through touch;
a memory;
a processor communicatively coupled to said memory and to said touch screen display via said bus, wherein said processor is configured to:
store information regarding a plurality of prior touch events on said touch screen display into an event buffer;
determine an average speed and a predicted direction of motion of a user interaction with said touch screen display using said plurality of prior touch events;
calculate a first prediction point using said average speed, said predicted direction, and a last known touch event on said touch screen display;
apply weighted filtering on said first prediction point using a measured line curvature to determine a second prediction point, wherein in order to apply said weighted filtering, said processor is further configured to determine said measured line curvature using said information regarding a plurality of prior touch events in said event buffer; and
render a prediction line between said last known touch event on said touch screen display and said second prediction point.

16. The apparatus of claim 15 , wherein in response to receiving a new touch event, said processor is further configured to remove said prediction line and render a line based on detected user input.

17. The apparatus of claim 15 , wherein said information is chosen from a group consisting of: X-Y coordinates, size, pressure and timestamp.

18. The apparatus of claim 15 , wherein said prediction line is drawn with a different screen attribute versus a line drawn based on detected user input.

19. The apparatus of claim 15 , wherein said event buffer uses a least recently used (LRU) replacement policy.

20. The apparatus of claim 15 , wherein in order to apply said weighted filtering, said processor is further configured to:
add said first prediction point to a front of said event buffer; and
starting with said first prediction point, iterate through each event in said event buffer to determine a weight using said measured line curvature and said information, wherein said weight is applied to said first prediction point to determine said second prediction point.

Assignees

• Nvidia Corp

Inventors

• Skaljak Bojan
• Toorians Arman
• Chu Michael

Classifications

• G06F3/04883 Primary

  for inputting data by handwriting, e.g. gesture or text · CPC title

• G06F3/0416 Primary

  Control or interface arrangements specially adapted for digitisers · CPC title

• G06T1/60

  Memory management · CPC title

• G06F3/038

  Control and interface arrangements therefor, e.g. drivers or device-embedded control circuitry · CPC title

• G06F3/03545

  Pens or stylus · CPC title