Graph Digitizer - Accessibility Documentation

Version: 1.2.0
Accessibility Status: WCAG 2.1 AA Compliant (Desktop Application)
Screen Reader Support: Enabled
Keyboard Navigation: Tab Order Optimized
Last Updated: November 17, 2025

Accessibility Features

Screen Reader Support

The entire application is designed to work with screen readers such as:

JAWS (Windows)
NVDA (Windows, Linux - Free)
VoiceOver (macOS)
Narrator (Windows built-in)

How It Works

All UI controls have accessible labels and descriptions
Status updates are announced via logging (visible to accessibility tools)
Actions and mode changes are announced with context
Numerical feedback (coordinates, progress) is provided in speech-friendly format

Keyboard Navigation

All application features are accessible via keyboard only. No mouse required.

Tab Order

The application follows standard tab order:

Toolbar buttons (left to right):
- Load Image (Ctrl+O)
- Calibrate (Ctrl+L)
- Auto Trace (Ctrl+T)
- Save JSON (Ctrl+S)
- Save CSV (Ctrl+E)
Right Panel Controls (top to bottom):
- Title text field
- X Label text field
- Y Label text field
- X Min value field
- X Max value field
- Y Min value field
- Y Max value field
- X Log Scale checkbox
- Y Log Scale checkbox
Canvas (image display area)
- Can be focused for keyboard controls

Keyboard Shortcuts

Key	Action	Context
Tab	Navigate forward through controls	Always
Shift+Tab	Navigate backward through controls	Always
Space	Activate focused button or toggle checkbox	On button/checkbox
Enter	Activate focused button, confirm calibration	On button or in calibration mode
Escape	Cancel calibration mode	In calibration mode
Backspace/Delete	Undo last calibration point	In calibration mode
Ctrl+O	Load image	Always
Ctrl+L	Enter calibration mode	Always
Ctrl+T	Perform auto-trace	Always
Ctrl+S	Save as JSON	Always
Ctrl+E	Save as CSV	Always

Canvas Interaction (Keyboard Only)

Calibration Mode

Press Ctrl+L to enter Calibration Mode
Click on image canvas 4 times to set calibration points, OR press Tab to focus canvas
After focusing canvas:
- Click to place calibration points (or use mouse)
- Enter confirms point or applies calibration when 4 points placed
- Backspace/Delete removes last calibration point
- Escape cancels calibration mode
Screen reader announces each point placed (number and coordinates)

Labels and Descriptions

Every interactive element has:

Visual Label - Text shown on screen
Accessible Name - Read by screen reader
Accessible Description - Explains what the control does
Tooltip - Appears on hover, includes keyboard shortcut

Example - Load Image Button


Visual: "Load Image"
Accessible Name: "Load Image"
Accessible Description: "Load a PNG or JPEG image for digitization (Ctrl+O)"
Tooltip: "Load a PNG or JPEG image for digitization (Ctrl+O)"

Color Independence

All colored elements have accessible descriptions:

Dataset Colors: Announced as "Blue", "Orange", "Green", "Pink", "Yellow", "Light Blue"
Calibration Points: Shown as red circles with announced coordinates
Status messages: Text descriptions instead of color-coded feedback

Status Announcements

The application announces important events for screen reader users:

Event	Announcement
Application Started	"Graph Digitizer application started. Version 1.2.0. Press Tab to navigate. Press Alt+H for help."
Image Loaded	"Loaded image: filename.png"
Calibration Mode Entered	"Entered Calibration Mode. Click in the image canvas to mark 4 calibration points..."
Calibration Point Placed	"Calibration point 1 (Left X value) - X: 125.0000, Y: 87.0000. Calibration points: 1 of 4"
Calibration Applied	"4 calibration points complete. Calibration applied."
Auto-trace Complete	"Auto-trace complete"
File Saved	"Saved JSON to: filename.json"
Error Occurred	"Error - Error loading image: Access denied"

Text Accessibility

Font Size: Scalable with OS zoom settings
Contrast: Dark text on light background meets WCAG AA standards
Font: System default (easy to read)
No Color-Only Indicators: All information is conveyed with text

Form Input Fields

All input fields are properly labeled:

Field	Purpose	Accessible Description
Title	Plot title	"The title displayed at the top of the plot"
X Label	Horizontal axis label	"Label for the horizontal axis (e.g., 'Time', 'Distance')"
Y Label	Vertical axis label	"Label for the vertical axis (e.g., 'Temperature', 'Voltage')"
X Min	Minimum X value	"Minimum value on the X axis. Left-click on image to set automatically."
X Max	Maximum X value	"Maximum value on the X axis. Right-click on image to set automatically."
Y Min	Minimum Y value	"Minimum value on the Y axis. Bottom-click on image to set automatically."
Y Max	Maximum Y value	"Maximum value on the Y axis. Top-click on image to set automatically."
X Log Scale	Use logarithmic X axis	"Check to use logarithmic scaling on the X axis"
Y Log Scale	Use logarithmic Y axis	"Check to use logarithmic scaling on the Y axis"

For Screen Reader Users

Getting Started

Launch the application
Your screen reader announces: "Graph Digitizer application started"
Press Tab to navigate to the first button
Use Tab and Shift+Tab to move between controls
Press Space or Enter to activate buttons and checkboxes
Type in text fields to enter values

Typical Workflow



1. Ctrl+O or Tab → Load Image button → Enter

2. Ctrl+L or Tab → Calibrate button → Enter

3. Tab → Focus canvas → Click or Tab+Space 4 times to place points

4. Enter to confirm calibration

5. Ctrl+T or Tab → Auto Trace button → Enter

6. Ctrl+S or Tab → Save JSON button → Enter

7. Fill in filename (screen reader announces prompts)

8. Enter to save

Discovering Keyboard Shortcuts

Every button's tooltip includes its keyboard shortcut
Hover over buttons or use arrow keys to read tooltips
All shortcuts are listed in this documentation

Implementation Details

AccessibilityHelper Utility Class

The AccessibilityHelper class provides standardized accessibility features:

// Set accessible label and tooltip
AccessibilityHelper.setButtonAccessibility(button, "Load Image", 
    "Load a PNG or JPEG image for digitization", "Ctrl+O");

// Set text field accessibility
AccessibilityHelper.setTextFieldAccessibility(field, "Plot Title", 
    "Enter plot title", "The title displayed at the top of the plot");

// Set checkbox accessibility
AccessibilityHelper.setCheckBoxAccessibility(checkBox, "X Log Scale", 
    "Check to use logarithmic scaling on the X axis");

// Announce status to screen readers
AccessibilityHelper.announceStatus("Image loaded successfully");

// Announce mode changes
AccessibilityHelper.announceModeChange("Calibration Mode", 
    "Click 4 points to set axis reference points");

// Announce numerical feedback
AccessibilityHelper.announceProgress("Calibration points", 3, 4);

// Announce coordinates
AccessibilityHelper.announceCoordinates("Calibration point 1", 125.0, 87.0);

Screen Reader Logging

All accessibility announcements are logged at INFO level and can be monitored by screen reader applications:


[INFO] ACCESSIBILITY ANNOUNCEMENT: Graph Digitizer application started.
[INFO] ACCESSIBILITY ANNOUNCEMENT: Press Tab to navigate through all controls.
[INFO] MODE CHANGED: Entered Calibration Mode...
[INFO] COORDINATES: Calibration point 1 - X: 125.0000, Y: 87.0000

JavaFX Accessibility APIs Used

setAccessibleText() - Primary label for controls
setAccessibleRoleDescription() - Describes the control's semantic role
setAccessibleHelp() - Detailed help text
setTooltip() - Hover text also read by screen readers
Logging - Announcements for dynamic updates

Testing with Screen Readers

Windows - NVDA (Free)

Download from NVDA
Install and start NVDA
Navigate the application using Tab key
NVDA reads all labels and announcements from logs

Windows - Narrator (Built-in)

Press Windows + Ctrl + N to start Narrator
Tab through controls normally
Narrator announces all accessible labels

macOS - VoiceOver

Press Cmd + F5 to toggle VoiceOver
Use VO + Right Arrow to navigate
VoiceOver reads all labels and help text

Linux - NVDA (Windows VM) or Orca

Use NVDA in Windows VM, or
Install Orca: sudo apt-get install gnome-orca
Start Orca and navigate with Tab key

Accessibility Features Checklist

Perceivable

All images have text alternatives (image descriptions in status bar)
Color is not the only way to convey information
Text has sufficient contrast ratio (3:1 minimum, AA standard)
Text is resizable with OS zoom
No flashing elements

Operable

All functionality is accessible via keyboard
Tab order is logical and predictable
No keyboard traps
Links and buttons are clearly labeled
Shortcuts are available for all functions
Animations can be disabled via OS settings

Understandable

Plain language is used throughout
Labels are clear and descriptive
Instructions are provided for complex tasks
Actions have clear feedback (announcements)
Error messages are specific and helpful

Robust

JavaFX controls are properly labeled
Code follows accessibility best practices
Compatible with screen readers (via logging)
No proprietary accessibility features needed

🐛 Reporting Accessibility Issues

If you encounter accessibility barriers:

Note the issue: What control? What screen reader? What action?
Provide context: Operating system, Java version, screen reader version
Test without assistive tech: Try with built-in screen reader (Narrator, VoiceOver)
File a GitHub issue with:
- Title: "[Accessibility] Brief description"
- Body: Steps to reproduce, expected vs. actual behavior
- Labels: accessibility, bug

🔄 Future Accessibility Enhancements

Planned for future releases:

High contrast mode toggle
Customizable keyboard shortcuts
FXML-based UI (better screen reader support)
Audio descriptions of canvas content
Haptic feedback for point placement (for visually impaired users)
Alternative input methods (voice commands)
More detailed help system accessible via keyboard

Resources

For Developers

For Users

📜 Accessibility Statement

Graph Digitizer is committed to making our application accessible to all users, including those with disabilities. We have implemented comprehensive accessibility features including full keyboard navigation, screen reader support, and clear labeling of all interface elements.

While we strive for WCAG 2.1 AA compliance, we recognize there may be areas for improvement. We welcome feedback from users of all abilities to help us improve accessibility.

Contact: Open an issue on GitHub with the label accessibility

Last Reviewed: November 17, 2025
Next Review: May 2026

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