set-pixel in bitmap-dc%

Sets a pixel in the bitmap.

The current clipping region might not affect the pixel change. Under X, interleaving drawing commands with set-pixel calls (for the same bitmap-dc% object) incurs a substantial performance penalty, except for interleaved calls to get-pixel, get-argb-pixels, and set-argb-pixels.

• (send a-bitmap-dc set-pixel x y color) -> void
     x : real number
     y : real number
     color : color% object