BIS Browser User Manual

Martin Klima
xklima@fel.cvut.cz

1. Introduction

BIS Browser is a part of Blind Information System (BIS). This system was developed on FEL CVUT Prague in 1999 to allow blind people to browse through graphical information. System uses text description defined in XML grammar. This description is read from either standalone XML file with the extension .XML or from standard graphical picture format .GIF. The *.GIF format in version 87a can carry any additional information except the graphical one. How the XML grammar looks is described in main document "Graphical communication with blind users". The description is generated using BIS Creator (see document "BIS Creator User Manual")utility. There is no artificial intelligence in this project; a human must do all description generation. To standardize the descriptions, methodology of description creation was defined. Also the grammar itself leads the description creator to follow the basic rules.

BIS Browser is a utility for browsing throw the XML description of a picture by blind user. The user interface of BIS Browser is optimized for use by blind users. The main features are:

• simplicity
  • The browser has only few basic states. All the states are clearly signed to enable an easy orientation in the description.
  • Information can be displayed using a filter or without any filtering.
  • All attributes can be hidden or shown for faster browsing.
• Keyboard input
• All functions are available from the keyboard.
• Also there is a graphical interface for non blind users which can be controlled by mouse.
• Text output
• All text information is displayed in a specific output line. The speech generating software is then set to watch this line. Also the Braille line can be set to this location.
• There is a cursor moving in this output line. This cursor is needed for proper function of some speech generating software. The focus is permanently set to this text line, because this is the only data source for the blind user.

2. Functionality

2.1. BIS Browser User Interface

Picture 1

User interface supports both the keyboard and mouse control. Thus all functions all reachable directly from keyboard or through the graphical user interface using mouse device.

Parts of UI:

2.1.1. Menu bar

Some actions and settings are reachable through it. All of them are also reachable through keyboard.

Table 1 displays the menu items

Table 1Description tree

Description tree graphically shows the contents of the XML description. It always starts from the root and then follows the description included in the grammar. One of its nodes is the active one. The active node’s detailed description is shown in attribute window and description window. Each node has also its graphical symbol assigned to it. There are these symbols:

2.1.2. Attribute window

Shows all visible attributes of the current node.

2.1.3. Description window

Shows all available descriptions to the current node.

2.1.4. Text output line

Text output line is the most important part of UI for blinded users. The user should set up his reading device (speech or Braille line) to this line. All fundamental information is displayed within this text line. To enable easy navigation in this line, there is a cursor that is controlled throw keyboard.

2.2. Functions

2.2.1. Launching

To start the BIS browser, type path\launch in the Run… menu where path is the current path to the Browser directory. The .bat file will start the Java virtual machine and the browser automatically. If you do not have the Java Virtual Machine installed on your computer, an error message will appear. If success, an empty browser window will appear. See Picture 1 for detailed description of the window.

2.2.2. Loading

To load an XML description, either press F9 or choose File/Load. A standard File Open dialog will appear. You can use mouse to choose the file to open or type the full location and name to the text box. Active cursor is located in this textbox, therefore there is no need to manipulate the active element for the blind user.

Confirm the selection by pressing Enter or by clicking the Open button. You can also abort the operation using Esc key or Cancel button.

2.2.3. Navigating

After the XML description file was loaded, root of the graphical representation of description is displayed. The root becomes the selected object. For the blind, the description of the selected object is always displayed in the text output line. Also all attributes are listed in the attribute window as well as descriptions in description window. Both the attribute and description window are for non blind user information only. The blind user gets full information from the text output line. Syntax of the information:

OBJECT NAME [{[ATTRIBUTE TYPE] ATTRIBUTE }]

Descriptions

To obtain the object’s current description on the text output line, press either PgUp or PgDown. In case, such a description exists, it is displayed in the form:

OBJECT NAME desc: DESCRIPTION

In case, there is no description available to this object, the "No description available" message will appear.

More descriptions can be displayed (if present) by pressing PgUP and PgDOWN keys. PgUP displays the previous description and PgDOWN the following description in the same form. In case, there is no description like this, "No previous description available" or "No next description available" message will appear on the text output line.

To get back to the navigation mode, press Esc.

The blind user’s reading device may by depended on the cursor position. Usually it follows the cursor and reads the text information. Sometimes it reads whole line, where the cursor is positioned, sometimes it’s necessary to move the cursor within the text. This function is implemented in BIS Browser and it’s reachable using the N key for moving the cursor to the left or the M key for moving the cursor to the right.

Semantic relations

Some descriptions may refer to other objects in the tree. This reference is called semantic relation. Nodes with this relation are graphically indicated by this icon: . There is a possibility to follow the relation, i.e. to quickly get to the related object in the tree. To do so, press Enter when such a description is currently displayed. The related object becomes the current one.

Attributes

All attributes may be omitted. This helps the blind to get faster global information about the picture. The main information is included in the structure itself. The additional attribute information creates about 20% of the complete description only. The attributes displaying can be switched of / on by pressing F5.

Also there is a possibility to display attribute type when displaying attributes by pressing F6 key.

Moving in description tree

The active node is indicated by blue frame. Also, this object is displayed in the text output line and on the Java system console.

To move the current object to its parent object press left arrow key. In case, the current object is the root, no action is performed. The last visited child object is remembered and when moving in the reversed direction, this object is chosen first. This helps the blind user to quickly check the parent object whenever needed and then get back to the previously current object.

To move the current object to its child object, press right arrow key. The last visited node becomes the current one. If none was visited on this level yet, the first becomes the active one. The description tree is expanded as needed to graphically display the actual state.

To move the current object to its upper respectively lower neighbor, press up arrow key respectively down arrow key.

To quickly reach the root node, press R.

Sometimes its suitable to get information about the current object in a different view. Such a function should identify the same object in different view and make it the current one. Then its possible to get more information about it.

To quickly get to the same object in the previous view, press the Home key. In case, there is no previous view, no action is performed.

To quickly get to the same object in the next view, press the End key. In case, there is no Next view, no action is performed.

3. Implementation

BIS Browser is implemented in Java programming language. Java is a modern, fully object language. The basic class hierarchy is shown on the following picture.

Filled classes and interfaces are implemented in this software.

Description of classes and interfaces:

Tree

Implements graphical tree. The structure of the tree is hold in TreeNode type variable. Only the root node and the current selected node is necessary to be remembered. This class implements the MouseListener interface so as to be able to react to mouse actions. When action is performed and the state of the tree is changed, the TreeEvent object is generated.

ScrollTree

Implements a scrollable graphical tree build on the Tree class. It does not extend the Tree class, only uses most of its methods. The public methods correspond to the Tree class public methods.

TreeEvent

Object of this class is generated whenever the state of Tree of ScrollTree class is changed.

TreeListener

This interface must be implemented by all classes that want to catch the TreeEvent object thrown by either Tree of ScrollTree objects.

TreeNode

All information about a tree node are stored in an object of this class. It contains pointers to its following and preceding node and an object of Object type. The toString method is applied to this object and the result is displayed in the graphical tree.

BISBrowserFrame

The main class containing the main method to be run. The user interface, mouse and keyboard events handling are implemented here.

BisTreeNode

Data structure needed for special navigating for blinded people within the tree. Implements last visited object remembering. Also implements the toString method that may vary by different objects.

OutputDevice & BISTextLine

Classes for text output. Ready for future interface possibly written in the C++ language.

Function

Static class containing methods that do not fit into any of the previous classes.

4. Function keys

5. Installation & system requirement

5.1. Software requirements

BIS Browser uses the Java virtual machine to run on. It’s developed under JDK 1.1. To run the browser on your computer, you must have JRE 1.1 installed or JDK 1.1 (or later release).

To run the application itself, no further installation is needed. Simply copy the directory to its destination and launch runme.bat file. This bat file will launch the Java virtual machine and BISBrowser application as well.

The software was tested on Windows 95 and Windows NT.

5.2. Hardware requirements

On PC, the Java Virtual Machine requires at least Intel 486 compatible processor or better, 8 MB RAM 32 is recommended, mouse device and graphic card VGA compatible.

In general, there are no special HW requirements compared to Windows 95 / 98 of Windows NT.

6. Appendix 1 Example

File flat.xml contains an XML description of a plan of a flat. The structural view contains the general description of the flat layout. Also, there is a semantic view that describes relations among rooms in this flat. This semantic view will help us to find way from one room to another. See Picture 1 for the plan of the flat.

Picture 1 - Scheme of flat

Farther in this appendix there is a detailed description of how to browse throw the flat.xml description. We assume, there is BIS Browser running on your computer. How the browser with no description loaded looks you can see on Picture 2.

Picture 2 - Empty Browser

• To load the flat.xml file, press F9 key. Standard load file dialog will appear (see Picture 3). Type the flat.xml full path and name into the file name text box or use mouse to choose it. Press ENTER or click Open button when ready.

Picture 3 - Description to open dialog

The description will be loaded. A graphical tree representing the structure of the description will be displayed with the root object active. All other objects are hidden at this moment. See Picture 4. ‘Root’ i.e. the name of this object is displayed in the text output line as well as on the Java console. Name Root is also the only attribute assigned to this node. List of attributes is displayed in the attribute window.

Picture 4 - Description loaded

We would like to see more of the description structure. To do so, press right arrow key.

• Description tree will expand the current node and display the structure of its children. Because no child object has been visited yet, the first in the list becomes active. In our case, there is only one child object of the root object: Picture A. Generally, it is possible to include more picture descriptions into one file. See Picture 5.

Picture 5 - Browsing in the description

• Now, we would expand the picture node. Press right arrow key to do so. The list of view appears. The first view in the list is always the structure one. This view is obligatory in the description. All other views are optional. These views are called semantic ones and describe semantic relations among objects of the picture. See Picture 6. There are both, the structural and semantic view in our example. Let’s see the structural first.

Picture 6 - View structure

• The structural view describes the structure of the picture using mainly hierarchical relations among objects. Each object has its parent object (at least the view object) and its name. It may also have one or more child objects, one or more attributes and one or more descriptions. Being a child object means, the object structurally belongs under the parent one. Also, the description should be assembled so that it is readable on each hierarchical level. When reading the lower hierarchical level (the child objects), the blind user should only get some more detailed information. Let’s see, how our example description looks like. Press right arrow key to get to the child object of the structural view. See Picture 7.

Picture 7 - Structural view

• Using Up & Down arrow keys, we can go throw objects on the same hierarchical level. We are interested in the kitchen. Get to the kitchen node and press right arrow key. The node expands and the child objects appear. The fact, there are some child objects is indicated in the graphical tree by + or – sign. The node may be also expanded or collapsed by clicking onto this sign by mouse.
  The contents of the kitchen appear. Again, you can browse throw these nodes and expand these with child objects for mere detailed description. In our example, there is no child structure below.
• We would like to see how to get from the kitchen to the bedroom. This is a special information stored in the semantic view. Press left arrow key until you get to the view node. Then press Down arrow key to get to the semantic view. Expand the view. Get to the object of our interest, the kitchen. None of the objects in this view has any child objects. The semantic relations among them are expressed by descriptions with reference to other object. Semantic relation is a non-structural relationship among objects. It means, the objects don’t belong logically one under another, there is a different king of relation among them. To see the description use PgUp & PgDown to browse through descriptions. See Picture 8.

Picture 8 - Semantic view

• Let’s see, what descriptions contains the kitchen node: connected to living room
  There is only one semantic relation in the kitchen description. We would like to follow this relation to get to the living room. To do so, press ENTER again when this relation is currently displayed. The referred object becomes the current one. From living room, there are three possibilities to go to.
• foyer
• balcony
• kitchen
• We don’t want to go to the balcony neither to the kitchen we just came from. Let’s go to the foyer. Press ENTER when relation to foyer is displayed. This is the result:
• bathroom
• bedroom
• child room
• living room
• The bedroom is on the list, i.e. we are in the destination. The way from the kitchen to the bedroom goes through living room and foyer.