[cairo] how can I save the pixels of a line, and draw the line with the pixels laterly.

[王旭光]

Hello everyone!
     I want to do the following 3 steps:
         1  save the pixels of the line (x1,y1)-- (x2, y2) in the cairo_t
         2  draw the line using a special color
         3  sometime later, draw the line using the pixels saved in step1. (the same as erasing the line).
    But I don't know how to finish the step1 and step3.
    Help me, thanks a lot.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.cairographics.org/archives/cairo/attachments/20091106/ddd0f80d/attachment.html