Multi-point contacts with pressure data on an interactive surface

1. A method of controlling a software application running on a computer system including an interactive display, the method comprising: displaying a Bezier curve on the display, including displaying two control points of the Bezier curve; detecting two contact points on the surface of the interactive display; detecting a pressure value at each of said contact points; defining an active region extending from each contact point, the size of each active region being dependent upon the detected pressure at each contact point; detecting an overlap of the defined active regions; determining control data associated with the contact points, wherein the control data is derived from a pointing device being a pen-type device providing the contact point; and defining a condition of the software application in dependence on:

(i) detection of said two contact points; (ii) the position data of the two contact points; (iii) the control data associated with the contact points; (iv) the pressure values associated with the contact points; and (v) the detected overlap.

2. The method of claim 1 wherein the control data is derived from the state of a switch of the pointing device.

3. The method of claim 1 wherein the control data is selection data.

4. The method of claim 1 wherein the condition defines a pivot point and a selected object is rotated by movement of the other contact point.

5. The method of claim 1 wherein the condition causes a selected image to be flipped.

6. The method of claim 1 wherein the condition causes a selected image to split in two.

7. The method of claim 1 wherein the condition causes a selected image to be cropped.

8. The method of claim 1 , further comprising: enabling a software function in dependence upon the detected overlap.

9. The method of claim 1 , wherein the effect of a detected pressure value at one contact point is dependent upon the pressure value at the other contact point.

10. The method of claim 1 further comprising: selecting an object displayed in dependence on the at least two contact points being coincident with said object; detecting pressure values from the contact points; and manipulating said object in dependence thereon.

11. The method of claim 1 further comprising: detecting the selection of two colour options at the at least two contact points; and generating a colour by mixing the selected colours in a ratio determined by the pressure values at the respective contact points.

12. A non-transitory computer-readable medium storing a program causing a computer to execute the method according to claim 1 .

13. A computer system for controlling an interactive display, configured to: display a Bezier curve on the interactive display; detect two contact points on the surface of the interactive display being control points of the Bezier curve; detect the position of the contact points; detect a pressure value at each of said contact points; define an active region extending from each contact point, the size of each active region being dependent upon the detected pressure at each contact point; detect an overlap of the defined active regions, determine control data associated with the contact points, the control data being derived from a pointing device being a pen-type device providing the contact point; and define a condition of a software application running on the computer system in dependence on: (i) detection of said two contact points; (ii) the position data of the two contact points; (iii) the control data associated with the contact points; (iv) the pressure values associated with the contact points; and (v) the detected overlap.