Slicer3:Human Interface and Style Guide for Developers

Slicer Human Interface Design and Style Guidelines

Introduction

3D Slicer (or Slicer) is a large and continuously developing application. Its base is designed to offer substantial core functionality, and its modules extend that functionality to include specialized and cutting-edge research tools and interoperability with other open source softwares. The development effort seeks to simultaneously ensure that Slicer meets the needs of a broad user community, that developers can easily contribute to and extend the application, and that the software remains easy to test and maintain.

These human interface design and style guidelines are a resource for Slicer developers who want to create module interfaces that are easy to learn, understandable and usable, and that conform to Slicer’s general appearance and behavior conventions. The recommendations in this document are designed to be easy for developers to apply and their adoption is strongly encouraged. However, a developer’s interface design can depart from convention when these guidelines appear inappropriate for a particular application.

Organization

This document is organized into the following two sections:

1. Slicer Module Design Principles

2. Slicer Widget and Interface Style Specifics

Within these sections, developers will find recommendations that promote usable and consistent Slicer module interfaces, and link to technical resources where appropriate.

Look and Feel

GUI Style: Try not to add style elements (like foreground and background color, font, relief, etc.) to the interface you create; let the options database (as set up by the vtkSlicerTheme class) specify the style for the widgets in your module so that all modules appear consistent within the Slicer3 application.

Confirm on Delete

Check vtkSlicerApplication::ConfirmDelete setting; if a user has requested to be presented with a confirm on delete, then give them that option.

Event Bindings

With respect to the specification of keyboard accelerators, please follow these three recommendations;

• Before assigning "hot-keys" to functionality, either in the main Slicer application or in a new module, please consult the table (and design plan) linked below to make sure the key is not already assigned.
• Across Slicer modules, try to use similar "hot-key" assignments for similar functionality; this consistency makes Slicer easier to learn.
• Once you assign "hot-keys" in your module, please add those mappings to the table for others to reference.

Application Font

Verdana is the font chosen for the 3DSlicer brand.

Maintaining consistency of type is an important component of maintaining a coherent look and feel for 3DSlicer and any related or derived visual communications. Verdana was designed specifically to be read on a digital display; it is recommended that we use Verdana (or Geneva) wherever possible in 3DSlicer's web presence and online tutorial materials, and wherever reasonable and appropriate in formal printed materials.

Within the software, since it can't be guaranteed that these fonts will be widely available on all platforms, Helvetica or Arial should be used as a substitute. Slicer's theme sets the application font to be Helvetica 8 normal. Please avoid typefaces with serifs.

Icons

Icons can be a powerful way to represent complicated information within a small footprint on the GUI panel. They associate a visual image with data, state, or a particular operation.

• They should be easy to parse, convey a strong metaphor, and not require significant time for a user to interpret.
• They should be memorable so that a user can recognize them quickly in future sessions with your module.
• If an icon already exists within 3DSlicer to represent the data, state or operation you want to indicate, then re-use that icon (indicate visibility with the open/shutting eye, for example.)
• Note: if the concept is too difficult to represent with a picture, then a text label can always be used instead!

When designing icons, do bear in mind that it's possible to offend users with images that have cultural or polictal connotations. Even colors can have connotations for users in different parts of the world that may be surprising and unintended for the designer and developer. Generally speaking, it's useful to avoid images that contain:

• icons that depict only hands or feet
• images of animals
• maps containing disputed boundaries or region names.
• lists of countries that are not in alphabetical order.
• pictures of flags
• pictures of money

Slicer icon conventions

3DSlicer icons should all be of dimension 21x21 pixels.

Enabled or Enabled + Selected icons should have:

• a white background (r=255, g=255, b=255, or #FF FF FF)
• a black hairline along the perimeter (r=0,g=0,b=0, or #00 00 00).

Disabled or Enabled + Deselected icons should have:

• a grey background, value (r=230, g=230, b=230, or hex value #E6 E6 E6)
• a grey hairline perimeter of value (r=178, g=178, b=178, hex value #B2 B2 B2).

Downloadable blank icons:

These icon blanks are provided for download and use:

• Enabled or Enabled+Selected:
• Disabled or Enabled+Deselected:
• Enabled Menubutton:
• Disabled Menubutton:

Icons currently used in Slicer's Base

Below is a figure of icons currently in use in 3DSlicer. If the icon you need is already used in Slicer, we encourage its re-use in your own module (the visibility icon is a good example). However, if an icon is re-used, make sure you are using it to convey the same meaning/function -- icons shouldn't have different meanings in different places. Finally, make sure any new icons designed for a module don't duplicate ones already in use elsewhere in Slicer.

Colors: application palettes

Currently being modified... The Slicer3 color palettes are shown below. Developers of code, web content and training materials are encouraged to make color choices for GUI components according to this palette, bearing in mind that some of the colors are linked with special meaning, such as error (errorRed), warning (warningYellow), and system (systemBlue) messages.

main palette

name	show me	R	G	B	hex	use in slicer
black		0	0	0	#000000	text on enabled widgets
white		255	255	255	#ffffff	GUI background
lightestGrey		229	229	255	#e5e5ff
lighterGrey		223	221	226	#dfdde2
lightGrey		174	174	174	#aeaeae
mediumGrey		153	153	153	#999999	unsaved data ?
darkGrey		82	82	82	#525252
darkOchre		181	100	21	#b56415
mediumOchre		228	166	32	#e4a620
brightOchre		243	172	34	#f3ac22
sliceYellow		237	213	76	#edd54c"
lightOchre		244	233	127	#f4e97f
darkOrange		194	74	24	#c24a18
mediumOrange		225	112	18	#e17012
brightOrange		244	130	20	#f48214
lightOrange		243	184	70	#f3b846
lightestOrange		239	213	128	#efd580
redTint		224	182	175	#e0b6af
darkGreen		68	86	50	#445632
brightGreen		104	143	66	#688f42
dustyGreen		138	165	111	#8aa56f	cor slice
greenTint		204	244	166	#ccf4a6
darkBlue		73	64	102	#494066
mediumBlue		98	91	129	#625b81	system message code
lightBlue		136	127	163	#887fa3	unsaved data?
slicerBlue		179	179	230	#b3b3e6

message palette:

name	show me	R	G	B	hex	use in slicer
errorRed		255	0	0	#ff0000	error message/dialog accent
systemBlue		15	102	192	#0f66c0	message/dialog accent
warningYellow		255	226	30	#ffe21e	warning message/dialog accent

accent palette:

name	show me	R	G	B	hex	use in slicer
magenta		255	0	255	#ff00ff	3D viewer cube & icon accent
purple		191	73	190	#bf49be	icon accent
darkPurple		139	39	133	#8b2785	icon accent
logoGreyBlue		113	127	152	#717f98	logo color & icon accent
IGTGrey		68	69	91	#44455b	logo color & icon accent
logoDarkGrey		48	56	60	#30383c	logo color & icon accent
logoLightYellow		240	217	138	#f0d98a	logo color & icon accent
logoMediumYellow		248	191	37	#f8bf25	logo color & icon accent
logoOrange		240	108	46	#f06c2e	logo color & icon accent
logoRed		247	45	30	#f72d1e	logo color & icon accent
NAMICBlue		0	99	181	#0063b5	logo color & icon accent
SPLGreen		0	153	102	#009966	logo color & icon accent