GRAPHICAL OBJECTS WITH STRETCH AND COMPRESSION PROPERTIES

摘要

To process the layout of graphical objects, elastic data structures are established for the graphical objects to define minimum and preferred sizes, stretch properties and compression properties. One application of elastics is with respect to text blocks where preferred width and compressibility of each text block is a function of the amount of text in the text block. Composite graphical objects include elastic properties computed from their components through add and max operations which are dependent on relative elasticities of the components. The positions of origins within graphical objects are defined by pairs of elastics in each of two dimensions. The default width or height preference of a graphic object can be overriden. Overriding elastics is an effective mechanism for altering the display characteristics of graphical objects while preserving certain display relationships. The elastics and dimensions of graphical objects are processed in a three pass layout negotiation. In the first pass, preferred sizes and elasticities of the graphical objects are computed along a first dimension. In a second pass, size values of the graphical objects along the first dimension are computed from the preferred sizes and elasticities, and preferred sizes and elasticities of the graphical objects along a second dimension are computed based on the size values of the graphical objects along the first dimension. In a final pass, size values of the graphical objects along the second dimension are computed from the preferred sizes and elasticities.