set-logical-function

Sets the current drawing mode for this object. The drawing mode determines how a source pixel (from a pen or brush colour, or source device context if using blit) combines with a destination pixel in the current device context.

• (send a-wx:canvas set-logical-function mode) -> void
      mode : small integer

  The possible values for mode and their meaning in terms of source and destination pixel values are as follows:

  wx:const-and              src AND dst 
  wx:const-and-invert       (NOT src) AND dst 
  wx:const-and-reverse      src AND (NOT dst) 
  wx:const-clear            0 
  wx:const-copy             src 
  wx:const-equiv            (NOT src) XOR dst 
  wx:const-invert           NOT dst 
  wx:const-nand             (NOT src) OR (NOT dst) 
  wx:const-nor              (NOT src) AND (NOT dst) 
  wx:const-no-op            dst 
  wx:const-or               src OR dst 
  wx:const-or-invert        (NOT src) OR dst 
  wx:const-or-reverse       src OR (NOT dst) 
  wx:const-set              1 
  wx:const-src-invert       NOT src 
  wx:const-src-and          AND src (Windows blit only: equivalent to SRCAND) 
  wx:const-src-or           OR src (Windows blit only: equivalent to SRCPAINT) 
  wx:const-xor              src XOR dst 
  

  The default is wx:const-copy, which simply draws with the current colour. The others combine the current colour and the background using a bitwise operation. (In X Windows, the bitwise operations are performed on color ids; on other platforms, the RGB values are combined bitwise.) The wx:const-xor mode is commonly used for drawing rubber bands or moving outlines, since drawing twice reverts to the original colour.