Rendering ink strokes of variable width and angle

Abstract

Apparatus and methods for dynamically rendering digital ink strokes of arbitrary stroke width while a user is drawing the ink strokes. An ink rendering system may receive sampled pen tip positions associated with a stylus or pen on a digitizer. The ink rendering system may further determine pen tip instances having particular shapes, sizes, and/or rotations, and may determine connecting shapes, preferably quadrangles, that connect between the pen tip instances. Smoothing techniques may also be used for existing digital ink.

1 . A method for rendering a digital ink stroke, comprising the steps of: 
 receiving a first pen tip instance;    receiving a second pen tip instance; and    determining a quadrangle based on the first and second pen tip instances,    wherein the first and second pen instances each are associated with data representing at least one of a size, shape, or rotation of the respective pen tip instance.    
   
   
       2 . The method of  claim 1 , further including the step of displaying a representation of the first pen tip instance, the second pen tip instance, and the quadrangle.  
   
   
       3 . The method of  claim 1 , wherein the first and second pen instances each are associated with data representing at least one of a size, shape, or rotation of the respective pen tip instance.  
   
   
       4 . The method of  claim 1 , wherein the step of determining the quadrangle includes determining the quadrangle to connect the first pen tip instance to the second pen tip instance.  
   
   
       5 . The method of  claim 4 , wherein the first pen tip instance is a rectangle, the step of determining including determining two sides of the quadrangle to each have one endpoint at a corner of the rectangle.  
   
   
       6 . The method of  claim 5 , wherein the rectangle is a square.  
   
   
       7 . The method of  claim 1 , wherein the first pen tip instance is a triangle, the step of determining including determining two sides of the triangle to each have one endpoint at a corner of the triangle.  
   
   
       8 . The method of  claim 1 , wherein the digital ink stroke is opaque.  
   
   
       9 . A method for rendering a digital ink stroke, comprising the steps of: 
 receiving a first pen tip instance;    receiving a second pen tip instance; and    determining a region connecting the first and second pen tip instances,    wherein the first and second pen tip instances are each associated with data representing an area defined by a contour of the respective pen tip instance.    
   
   
       10 . A method for rendering a digital ink stroke, comprising the steps of: 
 receiving a first pen tip instance;    receiving a second pen tip instance;    determining a plurality of quadrangles based on the first and second pen tip instances; and    determining a union of the plurality of quadrangles.    
   
   
       11 . The method of  claim 10 , further including the step of displaying a representation of the first pen tip instance, the second pen tip instance, and the plurality of quadrangles.  
   
   
       12 . The method of  claim 10 , wherein the first pen tip instance is a rectangle, the step of determining including determining two sides of each of the plurality of quadrangles to each have one endpoint at a corner of the rectangle.  
   
   
       13 . The method of  claim 1 , wherein the first and second pen tip instances each have an area defined by a contour.  
   
   
       14 . The method of  claim 1 , wherein the first and second pen tip instances are of different sizes or different shapes.  
   
   
       15 . The method of  claim 9 , wherein the region overlaps a portion of the area of each of the first and second pen tip instances.  
   
   
       16 . A computer-readable medium having computer-executable instructions for performing the steps recited in  claim 1 .  
   
   
       17 . A computer-readable medium having computer-executable instructions for performing the steps recited in  claim 9.