A Constraint-based Approach to Dynamic Colour Management for Windowing Interfaces

Selecting harmonious colours for traditional window systems can be a difficult and frustrating endeavor. At the root of this problem is the fact that typical window systems do not allow abstract properties of colours to be specified. Instead, they insist that users specify individual colour values exactly. When many colours are used, the value of each colour must be chosen to satisfy any relationships that exist between it and previously chosen colours. Unfortunately, the difficulty of colour selection often prevents users from taking full advantage of the functional benefits of colour, particularly that of resolving context. A more desirable approach is to allow the aesthetic and functional properties of colours to be specified and to allow users to select values for the colours they wish. The window system can choose the remaining colours using these properties. Another failing of typical window systems is that once a colour value has been determined it will not change without explicit direction from the user. When windows open or close the factors which motivated a choice of colour value may change. Unfortunately, if the user wishes the chosen colour value to change as the environment changes, he or she must typically perform the modifications. A dynamic window system assists the user in making these choices. By specifying colour properties as constraints, a dynamic window system can adjust colour values as the environment changes, to satisfy these constraints. The potential problems with dynamic window systems incorporating colour constraints are investigated in this thesis. An implementation that uses a distributed, jostling, constraint-solver based on a simple dynamical system shows that this approach is possible.