One of the most important aspects of presentation is alignment and placement of objects. Its theoretical foundation is based on Gestalt psychology: Human perception tends to order experience in a manner that is regular, orderly, symmetric, and simple. Visual impression is generated to an emergent whole based on several principles, called Gestalt laws. Two basic laws are:
- Law of proximity: an assortment of objects that are close to each other are formed into a group
- Law of similarity: objects will be perceptually grouped together if they are similar to each other
Placement of objects should be carefully done according to Gestalt theory.
Alignment pertains to the common-sense usage of visual positioning of text, images, controls in user interfaces. Alignment is an element of visual design that is easy to miss when done properly and easy to spot when it is not. Plasma seeks to achieve strong visual alignment in applications so that users don't have to wonder where elements on a page should go. Plasma seeks simplicity in alignment first.
Alignment in Plasma is:
- Simple: good alignment improves visual understanding and speed, and allows less thinking. Developers should strive to run alignment that is reduced to a minimum and build more of the UI from there on.
- Coherent: Users will see elements aligned in a way that follows common, natural, human-like behavior. This can be likened to taking notes. Titles will go first, then sub-headings, etc. The objective is that ideas follow a natural progression. Developers must prioritize their UI to meet these ideas.
- Reliable: Users will expect elements to be aligned the same across multiple applications. Users will come to expect that similar elements are grouped in a predictable fashion.
- Powerful: Users will expect powerful controls close together that will allow them to complete complex operations with only a few clicks and low visual travel of the UI to locate such controls.
- Guides and Margins In Plasma, alignment behaves like most with a horizontal, vertical, top, bottom, and center guides. As developers look to place controls or UI elements on their applications, they must set their guides or margins first.
- Limits Using the note paradigm for aligning elements, developers should not go more than 3 layers with left justification. Beyond 3 layers seems messy and less clear to the user.
Limit hierarchy to three levels or less.
Don't use more than three levels of hierarchy.
This same structure should apply to controls.
A General Note of Caution
When working with elements on a page and text, it is tempting to maximize the use of space by placing as many controls and labels as possible within the UI. The Plasma team recommends that you first:
- Organize your controls
- Prioritize them
- Remove redundancy
And then work in the fashion previously suggested using verticality for your controls. If your controls don't fit on one page because of the vertical alignment chosen, consider options such as:
- Using Tabs
- Create an "Advanced" window with extra controls
- Split your UI into smaller groups and categories
This should be done in order to preserve alignment conventions.