str4

Graphics

Highlighting Selected Elements

When a user has selected (i.e., pointed at) a displayed graphic element, highlight that element in some way so that the user can anticipate the consequences of any proposed action involving that selection.

Example: A dotted border might be displayed around a selected element, or perhaps a selected element might be displayed with video inversion to distinguish it from other elements.

See also:
See also:

Changing Position (Translation)

When editing graphic data, allow users to reposition selected elements on the display.

Comment: Repositioning displayed elements, whether done by "dragging" or "cut-and-paste", will usually prove easier than deleting an element and then recreating it from scratch in the desired location. A capability for moving elements will aid initial data entry as well as any subsequent editing of graphic data.

Comment: If an element is moved visibly by dragging across the display, it is probably not necessary to depict it in complete detail in all of its intermediate positions. It might suffice to show it in simplified outline until its new position has been confirmed by the user (or perhaps until it remains in one position for a fixed interval of time), at which point its details could be filled in again by the computer.
See also:

Deleting Elements

When editing graphic data, allow users to delete selected elements from the display.
Comment: Deletion/erasure will help when mistakes are made during data entry, as well as in any subsequent editing of graphic data. Deletion should be implemented as a reversible action. A general UNDO capability might suffice to reverse deletions. A more extended reversibility might be provided by saving deleted elements in a computer
scrap basket from which they can be retrieved any time during a work session in case a deletion is discovered to be a mistake.

Selecting from Displayed Attributes

During graphic data entry, allow users to specify attributes for displayed elements -- e.g., text font, plotting symbol, line type, color -- by selecting from displayed samples illustrating the available options.

Example: For line drawing a user might select from displayed samples of thick or thin, solid or broken, etc.

Comment: A display of available attributes will serve as a helpful reminder to the user, and will eliminate the need to assign distinctive verbal labels to the various options.

Comment: Samples of some attributes may be difficult to display. In complex graphics, for example, specification of line type might involve selection among "brushes", each of which has a "tip" defining the size and shape of the drawing area (a group of pixels) that the user can manipulate. Brushes might have squared tips to draw sharp lines, or rounded tips to draw lines with softer edges. By analogy with artistic painting, a "smear" brush might be provided to average or blend colors along its path. Selective erasure might be accomplished with a brush applying (returning to) the color of the display background.

Comment: In most applications, the current selection of data attributes should remain in effect until a new selection is made. In some cases, e.g., following selection of an "erase" attribute, it may help the user if a selected attribute reverts automatically to a default value at the completion of a transaction sequence.

Back	Home	Next