This little program demonstrates two basic graphics programming principles:
1) Simple “painting” code - basically, connecting a series of lines together as the user drags their mouse around.
2) An implementation of the built-in Windows API function “ExtFloodFill”, which can fill a contiguous region of an image. (Photoshop users may know this as the “paint bucket” tool.)
ExtFloodFill requires the following declaration (VB format):
Private Declare Function ExtFloodFill Lib "gdi32" (ByVal hDC As Long, ByVal x As Long, ByVal y As Long, ByVal crColor As Long, ByVal wFillType As Long) As Long
To use the program, draw several lines using the left mouse button, then fill contiguous regions (with random colors) via the right button.