BlackBerry Wireless Handheld User Interface Style Guide

BlackBerry Wireless Handheld User Interface Style Guide
BlackBerry Wireless
Handheld User Interface
Style Guide
Version 1.0
BlackBerry Java Development Environment Version 1.0
BlackBerry Wireless Handheld User Interface Style Guide
Last modified: 20 November 2003
Part number: PDF-06946-001
© 2003 Research In Motion Limited. All Rights Reserved. The BlackBerry and RIM families of related marks,
images and symbols are the exclusive properties of Research In Motion Limited. RIM, Research In Motion,
‘Always On, Always Connected’, the “envelope in motion” symbol and the BlackBerry logo are registered with
the U.S. Patent and Trademark Office and may be pending or registered in other countries. All other brands,
product names, company names, trademarks and service marks are the properties of their respective owners.
The handheld and/or associated software are protected by copyright, international treaties and various patents,
including one or more of the following U.S. patents: 6,278,442; 6,271,605; 6,219,694; 6,075,470; 6,073,318;
D445,428; D433,460; D416,256. Other patents are registered or pending in various countries around the world.
Visit www.rim.com/patents.shtml for a current listing of applicable patents.
While every effort has been made to achieve technical accuracy, information in this document is subject to
change without notice and does not represent a commitment on the part of Research In Motion Limited, or any
of its subsidiaries, affiliates, agents, licensors, or resellers. There are no warranties, express or implied, with
respect to the content of this document.
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Published in Canada
Contents
1 User interface design principles ....................................................................................................................................... 5
Overview .............................................................................................................................................7
User interface design principles .......................................................................................................8
2 BlackBerry interaction model ..........................................................................................................................................13
BlackBerry handheld interaction mechanisms.............................................................................15
Navigating in a BlackBerry application ........................................................................................16
3 Designing the interface ....................................................................................................................................................19
BlackBerry views ..............................................................................................................................21
User interface elements....................................................................................................................25
Creating an effective main screen ..................................................................................................32
Browser design principles ...............................................................................................................34
Handheld error prevention and recovery.....................................................................................36
1
User interface design
principles
This section provides information on the following topics:
•
Overview
•
User interface design principles
1: User interface design principles
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BlackBerry Java Development Environment
Overview
Overview
This document provides guidelines for designing a user interface for your BlackBerry handheld
application. It contains descriptions of BlackBerry controls, as well as guidelines and suggestions for
their usage.
Related resources
Refer to the following resources for additional information:
Resource
Description
BlackBerry Java Developer Guide
The BlackBerry Java Developer Guide provides an introduction to developing
applications for the BlackBerry Wireless Handheld. It contains sample applications as
well as conceptual material about the BlackBerry Java APIs.
BlackBerry Wireless Handheld User Interface Style Guide
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1: User interface design principles
User interface design principles
An effective user interface is extremely important to an end-user application. Designing an
application according to specific design principles can simplify a complex application. A simple,
effectively designed user interface creates a good user experience and dramatically increases user
productivity.
Consider the following principles when designing an application user interface.
User control
The user should always be in control of the application; to achieve user control, keep in mind the
following principles:
Responsiveness
The user must be able to navigate and perform actions quickly without having to wait for the
application. If there are long delays between the time the user performs an action and the processing
of the action, the user will not feel in control. Responsiveness can be improved by writing efficient
source code where possible, or by prompting the user with an hourglass icon, informing the user
that the application is processing.
User interface response time should be, at worst, 200 ms (1/5 of a second) or better. If an operation is
expected to take a long time (for example, a text search or a database query), then it should be
executed in the background. If this is not possible, a splash screen or wait icon should be used to
reassure the user that an error has not occurred.
Customization
Because user preferences differ, users should have the ability to customize the interface of the
application. This includes deciding what information to display in the message list and the order in
which to display information. By customizing the interface, the user can create an application that
best suits their typical, day to day usage pattern. However, the application should provide defaults
that are helpful for the majority of users.
Perform tasks at hand
The best interfaces are the ones that make tasks easier for users, without drawing attention to the
interface. The user interface should be designed to allow the user to simply and intuitively perform
a task. The best interfaces are the ones that are hardly noticed.
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User interface design principles
Intuitiveness
An interface should be as intuitive and straightforward as possible. One of the best ways to achieve
this is by using the object-action paradigm. The object-action paradigm refers to a design principle
that associates specific objects in the application with the actions that are performed on them. For
instance, on the BlackBerry handheld, a user can select a message from the message list and then
perform an action on it (such as view, reply, forward, or delete).
Context
Along with its intuitive design the BlackBerry handheld excels in its ability to provide a sense of
context to user interface design. With respect to a BlackBerry handheld application, context
describes the circumstances under which an action, or a particular situation, occurs. Context infers
that the user interface is adaptable and flexible, and changes to best meet the needs of the users
depending on the way in which the interface is used. In BlackBerry handheld applications, menus,
menu options, and menu defaults change depending on the context in which the application is used.
For example, when a user composes a message, the menu options change to provide different
functionality depending on the position of the cursor. When the cursor is positioned in the To field,
the menu options change to display only those options relating to this action.
Providing effective context can prove very difficult since it requires a great deal of planning and
usability testing. It is, however, extremely important to the success of your application since a good
sense of context can create an extremely intuitive and easy to use application.
Consistency
Consistency should exist throughout each task and between applications. Consistency improves the
user experience by providing a familiar set of actions or tasks across all applications on the
handheld. By creating this familiarity, the chances that the user will become confused or “lost” are
greatly decreased. The onus is on you, as a developer, to be aware of other applications being
written for the handheld so that your application interface is a consistent part of the whole
BlackBerry handheld solution. Consistency enables common interface elements to be reused.
In addition to providing consistent individual operations, block operations should be performed as
though they were individual operations. This is especially important if an operation fails in the
middle (for example, pasting data into a nearly full buffer or deleting files from a folder).
Clarity
The interface should be clear, not only from a visual point of view, but also from a conceptual point
of view. Clarity is an especially important design aspect because the BlackBerry handheld has a
small viewing screen. If the interface causes distractions by breaking visual flow, users might have
trouble maintaining control. If you are using icons, keep in mind that they will be small and if they
are cluttered, it will not be clear to the user how the icon is related to the interface that contains it.
BlackBerry Wireless Handheld User Interface Style Guide
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1: User interface design principles
BlackBerry handheld applications should not be considered Windows® applications. Using too
many controls will only emphasize the small size of the display.
Dialog and status boxes should contain brief and concise text. This text should not merely indicate
to users what they have done incorrectly; they should also indicate what action is necessary to
correct the problem.
Aesthetics
The BlackBerry handheld is a two-way wireless handheld — it is not a desktop solution. As such,
BlackBerry handheld applications should not be compared with Microsoft® Windows®
applications. Three-dimensional graphics, sounds, and flashing cursors on the handheld display are
inefficient and distracting. A simple design is generally the way to make handheld applications
aesthetically pleasing.
When the information on the screen changes, limit the changing data to one item at a time, by
keeping the user focused on one place at a time. When presenting a lot of information to users,
display the most important information first. For example, when presenting each address book
entry, display the name fields first, followed by the email address, phone, fax, and pager numbers
fields, and leave the Notes field to the end.
In addition, the application should not cause any unnecessary screen repaints, nor should it take
focus from other applications without permission.
The BlackBerry user interface engine maintains an aesthetically pleasing appearance by taking
advantage of the vertical nature of the trackwheel. Menu items and lists are presented in a vertical
fashion. Double-clicking (as opposed to two quick single clicks) is not desirable based on the size of
the handheld and the size of the trackwheel itself.
Feedback
Feedback describes the application's response to user input (for example, the appearance of a menu
when a user clicks the trackwheel). Feedback is crucial to the success of an application since it
defines and shapes the very way in which a user interacts with the BlackBerry handheld. Prompt
feedback is essential and the application should respond quickly to the commands of users. For
instance, one of the learning curves for new users of the BlackBerry is typing on the keyboard. Since
keyboard typing may take a while to get used to, new users will become frustrated quickly if
feedback from typing or invoking screens or menus is slow.
Forgiveness
The interface must allow users to change their mind and undo commands; essentially, it must be
forgiving. The following principles describe user interface forgiveness as it relates to the BlackBerry
handheld.
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User interface design principles
First, users should not be enabled to perform any destructive tasks without being warned (for
example, an action such as deleting a message must be confirmed before the action can occur).
When a destructive action occurs (or is about to occur) the user is always prompted by a warning
dialog box. This warning enables the user to undo or reverse an action before it is too late. However,
be careful with over prompting; it can cause a user to routinely ignore all prompts and therefore
cause unwanted, irreversible actions.
Second, avoid placing common menu items close to others that undo the task at hand (for example,
the Cancel menu item is not close to the Hide menu item).
Screen title
Every screen will have a title on the first line of the display. The title provides cohesion between
screens in the application. The title line should be used not only to inform users where they are, but
also to display brief information to help the users with the particular task at hand. For example,
when users perform a search in the address book application, the first line of the screen will display
the screen title plus the text typed to invoke the search.
Controls
Controls are tools such as icons and buttons that the user selects to issue commands. Keep the
number of controls on the screen display at any one time as small as possible. Too many controls on
the screen display will only emphasize the small size of the screen.
Errors
When encountering error conditions, the user should be informed of the error without being
inconvenienced. Attempts should be made to make the failure “graceful” such that no information
is lost. For example, if inserting a character in the middle of a full field, prevent further input (and
display a brief error message) rather then throwing out characters at the end of the buffer without
warning.
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1: User interface design principles
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BlackBerry Java Development Environment
2
BlackBerry interaction
model
This section provides information on the following topic:
•
BlackBerry handheld interaction mechanisms
•
Navigating in a BlackBerry application
2: BlackBerry interaction model
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BlackBerry Java Development Environment
BlackBerry handheld interaction mechanisms
BlackBerry handheld interaction mechanisms
When designing a user interface for your BlackBerry application, consider the BlackBerry input and
output mechanisms. The following diagram describes the input mechanisms for the BlackBerry
Wireless Handheld.
BlackBerry input mechanisms
While the BlackBerry keyboard and trackwheel are easy to use, they differ greatly from common
input devices such as the standard desktop keyboard and mouse. You should take into account the
following considerations when designing your user interface.
Keyboard and trackwheel interaction
The user should not have to alternate between using the keyboard and using the trackwheel to
navigate. For example, if users are entering data using the keyboard, they should not have to use the
trackwheel for some form of input and then go back to using the keyboard.
Most actions should be performed using either the keyboard and the trackwheel.
BlackBerry Wireless Handheld User Interface Style Guide
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2: BlackBerry interaction model
Trackwheel
The trackwheel is unique in that it has dual input capabilities since it can be clicked and rolled by
the user. While simple to operate, the wheel also has drawbacks. Quite often, users will overshoot
with the trackwheel or accidentally click it while rolling.
To counter this, the following should be considered:
•
forgiveness principles should take this into account
•
menu items and dialogs should not be grouped in such a way to cause the user to accidentally
do something destructive.
Escape button
The Escape button is used to cancel operations such as selecting text or sending a message. The
Escape button should always return the user to the previous home screen.
Feedback
Feedback is accomplished on the BlackBerry handheld by both visible and audible means. The
BlackBerry is able to use an assortment of audible tones to signal alarms, appointments, or incoming
calls. It also displays dialogs or text messages to display information to the user.
Navigating in a BlackBerry application
The main method of navigation in a BlackBerry application is through the use of the drop-down
menu. The menu provides the user with a list of actions that can be performed on a given item. A
user clicks the trackwheel to access the menu. The menu appears in the top right corner of the
screen.
You should avoid using buttons or cluttering the screen with custom controls. The menu provides
the means to display actions and tasks while using up little screen space.
Use default navigation whenever possible. When the user clicks the Close menu item or presses the
Escape button, the application should return to the previous screen or, if there is no previous screen,
the application should close. If the user has entered data or modified options on the screen, a
confirmation prompt should appear to enable users to save or discard changes.
Clicking the trackwheel should always lead to the next natural action, which is typically a return to
the previous screen or close the application.
When a user exits an application, the handheld Home screen should appear.
The following lists additional guidelines for trackwheel and keyboard interaction:
•
16
Remapped keys must always be returned to their original state upon exiting the application.
BlackBerry Java Development Environment
Navigating in a BlackBerry application
•
In multi-line text entry mode, the Enter key enables the user to input a new line.
•
The application must support text and numerical characters for data input based on the
QWERTY keyboard, including text modifier keys when appropriate.
•
In text entry mode, the trackwheel will move the cursor appropriately: moving the trackwheel
up or down moves the cursor up or down, pressing the ALT key and moving the trackwheel up
or down moves the cursor left or right.
•
In numeric entry fields, verify that the keyboard automatically defaults to numeric entry instead
of text. The user should be able to input numbers in a numeric entry field without having to
press the Alt key to enter numbers instead of text.
•
In an application, pressing the Escape button enables the user to return to the Home screen.
Pressing the Escape button repeatedly should always return the user to the Home Screen except
from within a text entry field.
•
From within the application, the Cancel or Close option should always "cancel" the operation.
The application should move one screen back toward exiting the application and returning to
the Home Screen.
•
All icons that require a hot key (such as an icon on the Home Screen) will have a unique hot key.
Each hot key that is used for any icon shortcut is unique to that icon.
BlackBerry user interface checklist:
•
Pressing the trackwheel Always invokes a menu
•
Pressing the Escape button Always returns to a prior screen or exits the application
•
The main application screen Always includes an Exit action as the last menu item (for example,
Close or Exit)
•
The user must be prompted to save when leaving a screen in which the data has been modified
•
Always prompt a user with a warning dialog before data is destroyed
•
All icons on the home screen must be enabled with a unique hot key
•
Verify that the application obtains and loses focus appropriately. The application should not
execute while it does not have the focus.
•
Verify that the keyboard is mapped correctly when inputting text into a field and remapped
correctly when the application exits
•
The user should always return to the Home screen when an application exits
•
BlackBerry applications should always be written to support localization. Text strings should be
retrieved from a separate resource bundle. Numbers, dates and time formats should reflect the
locale of the user.
BlackBerry Wireless Handheld User Interface Style Guide
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2: BlackBerry interaction model
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BlackBerry Java Development Environment
3
Designing the interface
This section provides information on the following topics:
•
BlackBerry views
•
User interface elements
•
Creating an effective main screen
•
Browser design principles
•
Handheld error prevention and recovery
3: Designing the interface
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BlackBerry Java Development Environment
BlackBerry views
BlackBerry views
The BlackBerry user interface was designed with simplicity and efficiency in mind. This was
accomplished by designing an interface that allows users to easily perform tasks and access
information
Conceptually, the BlackBerry user interface can be broken down into a set of standard view types. A
view type defines the basic layout of the application screen and application data.
The BlackBerry user interface consist of the following view types:
BlackBerry view types
The views are task oriented, since each view type was created to accomplish a single, specific task.
For example, the Composed screen enables users to compose notes or messages, while the options
screen enables them to view or modify an applications Options.
Contents view
The contents view, which is also called the functions view, typically forms the main screen of the
BlackBerry application. It is displayed when an application is selected from the Home screen and
itlists the components or objects associated with the application. The components can be ordered or
unordered. The meaning of an object is not necessarily affected by its order within the list.
The contents view type has two sub-types:
•
list view
•
details view
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3: Designing the interface
List view
The list view lists the objects within the applications, usually alphabetically. For example, the
message list is a type of list view. The message list lists all messages that were sent or received by the
user. The list displays the name, subject, time, and date of the message, as well as an icon that
displays whether or not the message was sent or received.
Message list
Since the list view often contains many items, the Search functionality should be made available to
allow the user to search for and access information given a text string or pattern. In the Message list
screen, the Search function can be accessed from the menu. In the address book, which is also a list
view, the Find function is used to perform a search on objects within the list.
Address book
The user enters the first letter of the name of the contact that they are searching for. The list narrows
to contain only contacts with names that start with that letter. As the user enters more letters from
the contact’s name, the list narrows to contain only the names of contacts that match the search
string.
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BlackBerry views
Details view
The details view is typically accessed from a list view screen. The details view provides another
layer of information about the current object in the list. The type of information displayed depends
on the type of object that was accessed. For example, when a user clicks the trackwheel on a message
in the message list, an email displays.
BlackBerry message
The details view type displays information in greater detail, and in some cases, allows you to
modify the data. The address book and task applications provide other examples of details view
types.
Composed view
The composed view is typically accessed by clicking an icon from the home screen. The composed
view differs from the details view in that it represents a view of an object in which relationships of
the parts contribute to the overall meaning of the application. In other words, the composed view
contains fields that allow you to interact directly with the application. For example, when the user
clicks on the calendar application in the home screen, the current week, month or day is displayed in
a composed view type.
BlackBerry calendar entry
You can view or edit each field in the week view calendar format. Editing data at the field level in
this view is reflected in the overall calendar application.
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3: Designing the interface
Options view
The options view displays information about the characteristics, attributes, or properties of an
object. It enables the user to view and modify the options or settings of a particular application. Not
all options can be modified.
Date/Time screen
The Date/Time screen enables users to change the way in which the date and time information
display on the handheld. An options view type is typically provided for each type of object.
Help view
The help view is not yet implemented.
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User interface elements
User interface elements
User interface (UI) elements, such as choice fields and dialog boxes, make up the core of a
BlackBerry application. They represent the lowest level at which style can be applied to an
application. Their adherence to a proper style is critical since they represent the exact point at which
a user interacts with the application.
Choice fields
Choice fields provide users with a horizontal list of options from which they can scroll up or down
to choose a value. A value is selected by rolling the trackwheel and clicking the selected value.
Ring tone choice field
Choice fields should order choices so that the index in the choice is directly correlated to the
collation or sort order, if applicable. The user will expect that rolling in the “up” direction will
increase this value, where “up” is defined as a UI constant, usually down. So the default behaviour
is that up is down and down is up. This should be changed through the constant Ui.UP.
For example, suppose there is a choice of numbers: 0, 1, 10, 100. The choices should be choice[0] = 0,
choice[1] = 1, choice[2] = 10, choice[3] = 100.
As another example, suppose the list is the months of the year. The choices should be choice[0] =
JANUARY, choice[1] = FEBUARY, ..., choice[11] = DECEMBER.
Choice field entries should be ordered logically, usually according to normal order, size or
alphabetically. For example, JANUARY, FEBRUARY, MARCH or BLUE, GREEN, RED.
Tip: The choice field is described in the BlackBerry Java API by the ChoiceField class. The ChoiceField. class contains
the functionality for creating customizable choice field components. It contains methods that enable you to define
the size of the choice field as well as the items that appear in the field.
for more information about the ChoiceField class refer to the BlackBerry Java API Javadocs
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3: Designing the interface
Notification dialog boxes
Notification dialog boxes should prompt a user whenever an operation occurs or when a
consequential action is about to take place such as deleting an item or changing the handheld time
or date. Prompting with a dialog box provides the forgiveness that protects users from themselves.
The BlackBerry handheld provides the following dialog box types:
Information
The information dialog provides information about the results of a recently executed command. It is
a modal dialog that offers the user no choices. It acts solely as a way to prompt the user with
important information.
Information dialog box
The user must acknowledge the message by clicking the OK button.
Question
The question dialog box prompts the user whenever a consequential action is about to occur. For
example, the user is prompted when a message is about to be deleted. The user must provide input
before the operation will proceed. The wording of the message must always be in the form of a
question. For example, “Save Changes to ...?” or “Cancel Compose?”
Question dialog box
The button text must always describe the action that the user is about to take and must always
answer the question.
Exclamation
The exclamation dialog box warns the user that a critical action or in some cases an error has
occurred. The exclamation dialog box also appears when the handheld is turned off.
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User interface elements
Exclamation dialog box
The wording of dialog questions should be consistent across the application. Yes/No dialogs boxes,
or binary dialog boxes that contain only the Yes and No options, should be avoided if possible.
Bad: Do you want to save the changes?
If possible, the user should be provided with another option and more information on the outcome
of the event. Dialog boxes should be simple and direct but verbose enough to avoid confusion.
Good: Changes have been made.
Cancel dialog boxes should always provide an escape route or cancellation action.
In accordance with the principal of non-destructiveness, the Delete item should always have a
confirmation dialog box in case the user meant to edit the item.
Proper BlackBerry confirmation dialog box
The application should not inhibit the use of notification dialog boxes. That is, when a dialog has the
focus, no other application can obtain focus and execute.
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3: Designing the interface
Menus
Menus provide the user with a non-scrolling list of options from which to choose. The menu
appears in the top right corner of the screen and is accessed by clicking the trackwheel. Once a menu
item is highlighted (by scrolling with the trackwheel), the item can be selected (by clicking the
trackwheel). Subsequently, a screen is displayed. Depending on the functionality of the item
selected, this screen may be the same as the previous one.
The vertical placement of the menu options plays a very important role in designing an effective
application. To increase familiarity with applications and to shorten the user's learning curve, the
order of items in menus should be as consistent as possible between all applications.
Care should be taken when choosing the default item in a menu. The default item should, of course,
be the item that will most likely be chosen by the user. This will also depend on the context in which
the current screen was entered and the item was clicked. Choosing an appropriate default menu
item will save the user time.
The default menu item will be highlighted and should appear in the middle of the list of items when
the menu first appears. The menu items that are selected more often by users should immediately
surround the default item, while the items that are selected less often should be placed further away
from the default item. Placing common menu options close to the default menu item minimizes
trackwheel scrolling by the user to locate the desired menu item.
Provide short but descriptive names for menu items. Menu item names should always be verbs
(actions). Limit menu item names to 12 characters. Capitalize the first letter of each word in the
menu item name.
Note: Be careful not to include too many items in a single menu. If your menu becomes too large, break the menu
down into two or more categories and create a new menu.
The following sections describe the recommended method for determining the order and layout of
menu items within a menu.
Category ordering
A menu can be broken down into a series of functional categories. Each category contains a group of
one or more related items that represent the actions to be performed. Categories are distinguished
from each other by menu separators.
Description of categories
Continuation actions
In some cases, an action will take several steps to complete. For example, to select an address when
composing an email, a user needs to first select the address, then select the addressing method. The
actions that complete the second step are called “Continuation Actions”. Use Email, Use PIN, and
Continue when composing a message are examples of this type of action.
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User interface elements
View changing actions
These actions change how the current screen appears. The only example in the current code is the
View All menu item which will restore a filtered list to the full list.
Item actions
In a list screen, item actions relate to the selected item in the list. For example, in the address book,
any actions related to contacts are in this category (for example, New Address, Edit Address, or
Delete Address). In a record screen, the item in question is the open record. In this context, examples
of item actions are Save Item or Delete Item.
Content actions
In a record screen, the lines represent content within the item that is opened. Content actions are
actions related to the content within the item. For example, “Select Name” to select a name to put in
a Name field in a search, “Clear Field”, or “Show Qualified Address” are examples of actions on the
content of an item.
Related function actions
These actions launch some other related function, for example, Compose Message, Search Message,
and Options.
Exit actions
Exit actions are those that will exit the current screen. These actions could be as straightforward as
Cancel and Close or more subtle like Previous Message and Next Message.
Proper BlackBerry menu
Item ordering
Within each category, actions are ordered from least to most destructive — new (creates), save
(preserves), and delete (destroys).
A menu separator should be used only to separate actions in different categories.
BlackBerry Wireless Handheld User Interface Style Guide
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3: Designing the interface
It is important when designing the layout of your menus to consider context. Think about the cursor
position and the operations that might be executed when the user clicks the trackwheel. Limiting the
available menu options and displaying only those menu options which are relevant to the current
context can save the user a great deal of time and lessen frustration.
Tip: The menu is described in the BlackBerry Java API by the Menu class. The menu class defines the functionality that
is common to all menus, such as adding and removing menu items, and provides the framework for creating menus
for your application.
for more information about the Menu object, refer to the BlackBerry Java API Javadocs
Controls
Controls are tools such as icons and buttons that the user selects to invoke commands.
Use the least number of controls on the screen as possible. Too many controls on the display
emphasizes the small size of the screen. Buttons are redundant since every click in a BlackBerry
application opens a menu.
Displaying a list of options
A list of options allows the user to provide input to the application by presenting a fixed group of
choices. Depending on the circumstances, a list should be displayed to the user in one of the
following ways:
•
Use check boxes when the user can select multiple options.
•
Use a drop-down list or radio buttons when the user can select only one option.
•
For presenting numeric options, use a drop-down list when the range of numbers is less than 20.
•
For larger ranges of numbers, use a gauge field (progress bar).
Be sure to provide a reasonable default value for each option list.
Forms
Forms enable a user to enter large strings of data into the application. When implemented correctly,
forms provide an effective means to enter text using the BlackBerry handheld. Consider the
following principles when designing a form.
When possible cache any data that has already been entered into a form and reload the information
into the form the next time the page is loaded. This saves a user from re-entering the same data each
time the page is loaded, such as a username.
To prevent input errors, you should clearly identify the required fields in the UI, and verify that the
required fields are filled in correctly before submitting the form. If the form has errors, provide a
descriptive message to the user describing which field needs to be corrected.
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User interface elements
When a field has no external dependencies and contains only simple information, then it might be
possible to validate the field either at the time of information entry or when the user leaves the field.
For example, in the BlackBerry calendar application, the date field automatically corrects apr 31 to
apr 30 when April is selected from the Month list. For fields that depend on other fields or those that
require complex input (for example, phone numbers) validate the form when it is submitted.
Fields
Fields enable users to enter formatted strings of text into an application. Consider the following
principles when designing a form.
Use a text filter on a field to permit only valid characters (for example, for an email address or phone
number field), and set an appropriate maximum number of characters.
When creating a password field, be sure to echo the text to the screen as an asterisk. This helps to
shield the password from third-party eavesdroppers.
Non-editable fields should be distinguishable from editable fields. It should be obvious to users
when they cannot edit a field.
The BlackBerry Wireless Handheld supports the following field types:
Field type
Description
BasicEditField
an editable simple text field with no formatting; this is the most common field type and
should be used to display simple text
AutoTextEditField
an editable text field designed to provide autotext support; when a word is entered that is
in the autotext database for the current locale, this field replaces it
BitmapField
displays a bitmap
ButtonField
displays a button control
CheckBoxField
displays a checkbox control; the checkbox field toggles a value
pressing the space key, or clicking the trackwheel (when a checkbox field has the focus)
toggles its state
ChoiceField
displays a list of scrolling choices
DateField
displays a date; the date can be displayed in a number of different formats
EditField
displays a simple text field that can be edited by the user
GaugeField
displays a horizontal bar that you can use for numeric selection or as a progress indicator;
the GaugeField provides a level of responsiveness to the application
LabelField
displays a simple label
ListField
contains rows of selectable list items
NullField
represents a field of 0 size
NumericChoiceField
displays a field that supports choosing from a range of numeric values
ObjectChoiceField
displays a choice field that supports a list of object choices
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3: Designing the interface
Field type
Description
ObjectListField
displays a list of objects
PasswordEditField
displays an editable text field designed specifically to handle password input.
When the user enters text into a PasswordEditField, the text is stored in a private buffer and
appears to the user as a string of asterisks. This field does not have any automatic input
replacement nor does it support cut and paste operations, so the typed text is exactly what
is typed.
RadioButtonField
displays a radio button control
RadioButtonGroup
displays a set of related radio button fields
RichTextField
displays a read-only field that supports richly formatted text; this field does not permit the
user to enter or edit its text
SeparatorField
displays a field which draws a horizontal line across it's width. The SeparatorField is used to
separate groups of choices within menus
TreeField
displays a simple field to show a tree structure to show a relationship between items (such
as folders and documents)
Tip: for more information about Field types, refer to the BlackBerry Java API Javadocs
Lists enable you to create directories of items through which users can scroll and select individual or
multiple entries. Lists are scrolled vertically using the trackwheel. The BlackBerry address book is
an example of a List object.
Ribbon icons
Icons should be simple to comprehend and should represent a meaningful association with the
application it calls. Icons must be 26 by 26 pixels in size, with a color depth of 65,000 colors. When
creating an application, include both a color icon and a monochrome icon in the resource files for the
application. At start-up, the application will automatically select the appropriate icon to display
depending on whether or not the handheld has a color screen.
Creating an effective main screen
Most BlackBerry applications share similar main screen characteristics in terms of appearance and
functionality. These characteristics are dictated both by the design of the trackwheel and the size
and shape of the screen. For this reason, most BlackBerry applications should adhere to a common
set of standards.
The main screen of a typical BlackBerry application should have the following characteristics:
•
32
title bar at the top with a separator line after the title
BlackBerry Java Development Environment
Creating an effective main screen
•
optional standards sized non-scrolling region at the top of the screen (called the banner) that
displays the date and time and the radio and battery status of the handheld. Note that while the
banner is optional and is not suited for all applications, it is a good idea to include at least
battery and signal information, especially in applications that use the radio.
•
main scrolling section with vertical layout
•
menu with a Close menu item
•
close action when the user clicks the Close menu item or presses the Escape button
Each screen displays an appropriate title bar that describes the contents of the screen. For game
applications, an appropriate title bar is required only when the user initially enters the game from
the Home screen.
Message List main screen
In the previous figure, the Message list screen of the mail application adheres to the principles stated
previously. It features a non-scrolling region containing the date and time, a vertically scrolled
message and a menu with a close item. The application closes when the user presses the Escape
button.
In the following figure, the search functionality of the address book uses the title bar to prompt the
user to enter a search string.
Search screen
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3: Designing the interface
Tip: The application main screen is described in the BlackBerry Java API by the MainScreen class. The MainScreen class
defines the components, such as the title bar and main scrolling regions, that make up the common features of a
typical BlackBerry application. Most of the main screen functionality is provided in this class.
for more information, refer to the BlackBerry Java API Javadocs
Browser design principles
In a wireless environment, you should typically deliver related content on as few pages as possible.
Although a page with more content might take a few seconds longer to download to the browser,
users do not have to make subsequent requests, and the information is available even when users
move outside an area of wireless coverage. Because the BlackBerry handheld provides a trackwheel
for scrolling, users can scroll through several screens of text easily.
For example, in WML pages, put related cards in the same deck whenever possible so that the
document only has to be loaded once. If the deck contains a relatively large card that many users
might not want to view, save the card in its own deck to minimize download time.
If you divide related content into more than one page, make links to related content easily
accessible. Make sure that links to related content are visible in a non-scrolling area of the page or at
the top of the page.
Design web pages to use the BlackBerry handheld screen effectively. The handheld has a larger
screen than many other mobile devices, such as cellular phones.
Text entry
Text entry on a cellular phone keypad can be difficult, so effective site design for WAP browsers
often mandates that, whenever possible, users should not be required to type text using the keypad.
This restriction is not applicable to the browser; users are often comfortable using the keyboard to
type text into web forms. You should not require users to type redundant or anticipated
information, but you can expect users to type text using the keyboard when appropriate.
The browser supports both the <input type="text"> and <textarea> elements in HTML, and
<inputtype="text"> in WML.
Minimize download time
Download time is affected by three factors: content size, wireless network, and protocol
characteristics. For example, a 15 KB file can take between 30 and 50 seconds to download through a
WAP gateway on a GPRS network.
34
BlackBerry Java Development Environment
Browser design principles
The best way to improve download time and provide a high-quality user experience is to reduce the
size of your web pages. Do not include unnecessary content in web pages. Use images only when
necessary, and reduce image file size as much as possible.
Consider using a cascading style sheet (CSS) to render your HTML page. A cascading style sheet
enables you to define the look of your web page by defining styles and fonts externally. Cascading
style sheets dramatically decrease the time it takes to download and display your webpage.
Improve rendering time
Rendering on the browser is much faster than download times, but large content can still require
several seconds to parse and display. WML typically renders more quickly than HTML or XHTML
content.
The Mobile Data Service (MDS) optimizes browsing by processing HTML content before sending it
to the browser. The Mobile Data Service filters unsupported markup and converts content into a
tokenized format that the browser can display efficiently.
In addition, you can improve rendering times by processing and filtering content at an intermediate
server between the web server and the handheld.
Images
•
use well-defined images and clear color contrasts
•
fonts that are saved as images should not be anti-aliased; anti-aliasing smooths edges by
blending the background and foreground colors and anti-aliased images do not display
optimally
•
if you need to shrink an image to better fit the smaller screen, when possible, you should redraw
the image; scaling down the image results in blurred edges that display poorly
•
in web pages, remember that users can specify whether images should be loaded or not; images
should not be critical to the effectiveness and usefulness of your web site
Note: Remember that not all users have the same handhelds. Create images that render well on both
monochromatic and color screens. Always provide descriptive alternate text for images just in case.
Web content
To deliver the appropriate content to wireless browsers, you can write a script to deliver different
content depending on two factors:
•
Browser type: In an HTTP request, the browser includes a User-Agent header that identifies
itself. Use this header to deliver different content to desktop browsers than to wireless browsers.
You can also deliver different content to BlackBerry handhelds than to other devices.
BlackBerry Wireless Handheld User Interface Style Guide
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3: Designing the interface
•
Content type: In an HTTP request, the browser includes an Accept header that specifies the
content types that it accepts. Use this header to deliver content that the browser can accept. For
example, the browser on Java-based BlackBerry handhelds supports WML and HTML, but the
browser on C++-based BlackBerry handhelds supports WML only; handhelds with color display
support .jpg images, but other handhelds do not.
Handheld error prevention and recovery
Applications must warn the user about data loss before executing any function that might result in
data loss.
For any text entry field where data has been entered, the application must post a message box
warning the user of data loss for any functions that can result in data loss (for example, cancel or
close).
It is important to test whether or not the application will continue to function properly when it loses
focus, is halted, or is sent to the background.
Perform the following actions to test for proper functioning:
1.
Press and hold the Alt key and press the Esc button to task switch.
2.
Insert the handheld into the holster.
3.
When an email or calendar notification occurs, remove the handheld from the holster.
If the application is functioning correctly, it will continue to run in the background or maintain
state until it regains the focus.
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BlackBerry Java Development Environment
Handheld error prevention and recovery
BlackBerry Wireless Handheld User Interface Style Guide
37
©2003 Research In Motion Limited
Published in Canada.
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