Thursday, July 21, 2016

How Much Is Too Many?

When designing or updating a software product, one need to consider both human and technical factors. Whenever I'm referring to a form, the same goes for web pages.  

Some Biological Limits: 

Frequently auto-refreshing tables (each 10-20 seconds) and frequently opening or closing forms are very tiresome for the eyes.

The visual acuity is a spot (a spatial arc of 10/360 degrees), suitable to hold a text column for reading - in practice this is about 40 characters per line with the default medium font (when one's eyeballs are enforced to move horizontally, the text line is too long).

Some Psychological Limits:

When a document's background image distracts the attention (intensive colors, crowded patterns, reduced contrast between background and text), the users get tired in short time.

Our distributive attention can manage up to 6-7 things, consequently a form should not have more then 6-7 groups of controls (menus, tabs or groups) and a group should not have more then 6-7 controls (except labels).

When this limit is exceeded, the user is feeling overwhelmed and frustrated by the user interface.

The Business Logic:

The quantity and frequency of the data exchanges with other computers decides what networking solution we need.

The type of database engine, software and hardware we need depends on the number and contents of documents, archives and processing requirements.

Resource Management:

A Windows application is a collection of modules (executables and libraries), which can be shared by multiple users across a network.

Our local copy needs to accomodate with our local hardware resources, and it should behave decently when consuming network resources or accessing remote servers.

Forms and Controls:

When designing the user interface it's important to keep a good balance between user requirements and technical limitations. 

Considering the answers to the below questions will help in structuring the user interface.

How many forms can I have in a project? Maybe 2, 4 or 10 - it depends on how many controls contain in total.

Each control is a window using memory, handling events, and it needs to be (re)painted from time to time. Consequently each control is a resource consumer of RAM, processor, and video capabilities.

How many controls can I have on a form? Counting all the object tree items for a form can help us evaluating our forms. If our form contains more then 50-100 controls, it's time to think about splitting it in two.

It's important to know, that using tabs is good for making our user interface tidy, but all the controls present on a tab are created "at once" with the parent form, regardless of their visibility.

The more powerful a machine is, its limits are the higher, but spreading controls over multiple forms will always be a necessity. 

(2011 - 2014)

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