1. A non-transitory computer-readable media comprising instructions stored thereon, the instructions, when executed by one or more processors, cause the processors to perform operations comprising: receiving a first handwriting input from a user, the first handwriting input comprising a plurality of handwritten strokes, and the plurality of handwritten strokes forming multiple recognition units distributed along a respective writing direction associated with a handwriting input area of a handwriting input interface; rendering each of the plurality of handwritten strokes in the handwriting input area as the handwritten stroke is provided by the user; starting a respective fading process for each of the multiple recognition units after the recognition unit is completely rendered, wherein during the respective fading process, the rendering of the recognition unit in the first handwriting input are becomes increasingly faded; receiving a second handwriting input from the user over a region of the handwriting input area occupied by a faded recognition unit of the multiple recognition unit; and in response to receiving the second handwriting input: rendering the second handwriting input in the handwriting input area; and clearing all faded recognition units from the handwriting input area.