Online Annotation

As the user writes, the system runs a background thread which applies the above stroke grouping technique and recognises the symbols that the user has written.

As mentioned in Section 4.3.2, there is a delay between the user's writing and the system's processing of their strokes. The number of strokes ahead that the system lets the user proceed is automatically determined by analysing the data used by the character recogniser. The limit is set to twice the number of strokes in the character with the largest number of strokes. With the current set of data for the character recogniser, the lag is eight strokes.

As characters are recognised, the system places a shaded bounding box over them and annotates the box with the character that the system has determined it represents.

  

Figure 4.5: A user beginning to enter a formula. The first three characters have been recognised, and the remaining two are still waiting to be recognised.

Figure 4.5 shows a screen capture of the drawing area of the program as a user is beginning to enter a formula. The first three symbols have been recognised by the system and their bounding boxes are marked and annotated with the system's current interpretation. As a character is recognised, the colour of its strokes are changed to indicate that the recognition has taken place.