Skip to main content
Web Access provides a powerful browser-based interface for remotely controlling QLC+. Access your lighting setup from any device with a web browser, including smartphones, tablets, and computers.

​
Overview

Web Access features:
  • Browser-based control (no app required)
  • Virtual Console remote access
  • Simple Desk web interface
  • WebSocket real-time updates
  • Multi-user support
  • Authentication and security
  • Responsive mobile-friendly design

​
Architecture

​
HTTP Server

Web Access runs an embedded HTTP server: 
// From webaccess.h:43
class WebAccess final : public WebAccessBase
{
    Q_OBJECT
public:
    explicit WebAccess(Doc *doc, VirtualConsole *vcInstance, 
                      SimpleDesk *sdInstance,
                      int portNumber, bool enableAuth, 
                      QString passwdFile = QString(),
                      QObject *parent = 0);
};
Constructor Parameters:
  • doc: Reference to the QLC+ document
  • vcInstance: Virtual Console instance for widget rendering
  • sdInstance: Simple Desk instance for direct DMX control
  • portNumber: TCP port for the web server (default: 9999)
  • enableAuth: Enable password authentication
  • passwdFile: Path to password file

​
WebSocket Communication

Real-time updates use WebSocket protocol: 
// From webaccess.h:73
protected slots:
    void slotHandleWebSocketRequest(QHttpConnection *conn, QString data) override;
    void slotHandleWebSocketClose(QHttpConnection *conn) override;
WebSocket provides:
  • Bi-directional communication
  • Low latency updates
  • Efficient data transfer
  • Persistent connections
WebSocket connections remain open, allowing the server to push updates to the browser instantly when fixture values or widget states change.

​
Virtual Console Access

​
Widget Rendering

Virtual Console widgets are rendered as HTML: 
// From webaccess.h:54
QString getWidgetHTML(const VCWidget *widget) const;
QString getFrameHTML(const VCFrame *frame);
QString getSoloFrameHTML(const VCSoloFrame *frame);
QString getButtonHTML(const VCButton *btn) const;
QString getSliderHTML(const VCSlider *slider);
QString getLabelHTML(const VCLabel *label) const;
QString getAudioTriggersHTML(const VCAudioTriggers *triggers) const;
QString getCueListHTML(const VCCueList *cue);
QString getClockHTML(const VCClock *clock) const;
QString getMatrixHTML(const VCMatrix *matrix);
Supported widgets:
  • Buttons: Start/stop functions
  • Sliders: Value control
  • Frames: Widget containers
  • Solo Frames: Page-based containers
  • Cue Lists: Step-through sequences
  • Labels: Text display
  • Audio Triggers: Audio-reactive controls
  • Clocks: Time display
  • Matrices: RGB matrix control

​
Complete Virtual Console

// From webaccess.h:67
QString getChildrenHTML(const VCWidget *frame, int pagesNum, 
                       int currentPageIdx);
QString getVCHTML();
The complete Virtual Console is rendered recursively:
  1. Start with root frame
  2. Render each child widget
  3. Handle nested frames
  4. Apply styling and layout
1

Open Browser

Navigate to http://[QLC+_IP]:9999
2

Authenticate

Enter password if authentication is enabled
3

Select View

Choose Virtual Console or Simple Desk tab
4

Control

Interact with widgets as you would in QLC+

​
Simple Desk Web Interface

​
Web-based Simple Desk

// From webaccess.h:69
QString getSimpleDeskHTML() const;
The web Simple Desk provides:
  • Channel sliders (32 per page)
  • Universe selection
  • Page navigation
  • Value display
  • Reset controls

​
Integration with Simple Desk

The web interface communicates with the Simple Desk backend: 
// From simpledesk.h:110
/** Web access helpers (absolute address based) */
int getSlidersNumber() const;
int getCurrentUniverseIndex() const;
int getCurrentPage() const;
uchar getAbsoluteChannelValue(uint address) const;
bool isChannelOverridden(uint address) const;
void setAbsoluteChannelValue(uint address, uchar value);
void resetAbsoluteChannel(uint address);
The web Simple Desk displays 32 channels per page. Use page navigation to access all 512 channels of the universe.

​
Real-time Updates

​
Widget State Changes

Widget state changes are pushed to connected browsers: 
// From webaccess.h:80
protected slots:
    void slotButtonStateChanged(int state);
    void slotButtonDisableStateChanged(bool disable);
    void slotLabelDisableStateChanged(bool disable);
    void slotSliderValueChanged(QString val);
    void slotSliderDisableStateChanged(bool disable);
    void slotAudioTriggersToggled(bool toggle);
    void slotCueIndexChanged(int idx);
    void slotCueStepNoteChanged(int idx, QString note);
These slots receive signals from Virtual Console widgets and broadcast updates via WebSocket.

​
Function Status

// From webaccess.h:76
protected slots:
    void slotFunctionStarted(quint32 fid) override;
    void slotFunctionStopped(quint32 fid) override;
Function start/stop events update:
  • Button colors (active/inactive)
  • Cue list position
  • Status indicators

​
Grand Master

// From webaccess.h:102
protected slots:
    void slotGrandMasterValueChanged(uchar value);
Grand Master slider is synchronized across all clients.

​
Authentication

​
Password Protection

When authentication is enabled:
  1. Browser requests a page
  2. Server checks for valid session
  3. If no session, redirect to login
  4. On successful login, create session cookie
  5. Grant access to protected resources

​
Password File Format

The password file is a simple text file: 
username:password
For production use, consider using HTTPS and strong passwords. The embedded server supports basic authentication but not encryption by default.

​
Resource Files

​
JavaScript and CSS

// From webaccess.h:105
protected:
    QString m_JScode;
    QString m_CSScode;
Web Access includes:
  • JavaScript: Client-side logic and WebSocket handling
  • CSS: Responsive styling for mobile and desktop
  • HTML: Widget rendering templates

​
Static Resources

Static files served:
  • webaccess-v5.html: Main HTML page
  • webaccess-v5.js: JavaScript code
  • webaccess-v5.css: Stylesheet
  • simpledesk-v5.js: Simple Desk JavaScript
  • simpledesk-v5.css: Simple Desk stylesheet

​
Project Management

​
Remote Project Load

// From webaccess.h:108
protected:
    void handleProjectLoad(const QByteArray &projectXml) override;
Web Access can:
  • Load projects remotely
  • Upload workspace files
  • Store fixture definitions
  • Manage autostart projects
// From webaccess.h:109
bool storeFixtureDefinition(const QString &fxName, 
                           const QByteArray &fixtureXML) override;
void handleAutostartProject(const QString &path) override;

​
Signals for Document Control

// From webaccess.h:112
signals:
    void toggleDocMode();
    void loadProject(QString xmlData);
    void storeAutostartProject(QString filename);
Remote project management allows you to configure QLC+ headless installations without physical access to the machine.

​
Multi-User Support

​
Concurrent Connections

Web Access supports multiple simultaneous connections:
  • Each browser gets its own WebSocket connection
  • State changes are broadcast to all connected clients
  • Users see the same Virtual Console state
  • Changes from one user are visible to others

​
Connection Tracking

// From webaccess.h:74
void slotHandleWebSocketClose(QHttpConnection *conn) override;
The server tracks:
  • Active WebSocket connections
  • Client IP addresses
  • Connection timestamps
  • Session states

​
Mobile Optimization

​
Responsive Design

The web interface adapts to screen size:
  • Touch-friendly buttons (larger hit areas)
  • Swipe gestures for sliders
  • Responsive layout for phones/tablets
  • Portrait and landscape support

​
Performance Considerations

  • Efficient WebSocket messages (minimal data)
  • Throttled updates (prevent flooding)
  • Client-side rendering (reduce server load)
  • Compressed assets

​
Configuration

​
Server Settings

  1. Port Number: Default 9999, configurable in settings
  2. Authentication: Enable/disable password protection
  3. Password File: Path to credentials file
  4. Auto-start: Launch Web Access with QLC+

​
Network Configuration

For remote access:
  • Ensure port is open in firewall
  • Configure port forwarding if needed
  • Use static IP or DNS name
  • Consider VPN for security
1

Enable Web Access

Go to Settings → Web Access
2

Configure Port

Set desired port number (default: 9999)
3

Enable Authentication

Turn on password protection and set password file
4

Start Server

Toggle Web Access on
5

Test Connection

Open browser to http://localhost:9999

​
Best Practices

  • Security: Always use authentication on public networks
  • Network: Use reliable WiFi or wired connection
  • Browsers: Modern browsers work best (Chrome, Firefox, Safari)
  • Testing: Test thoroughly before live events
  • Backup Control: Keep traditional interface available as backup
  • Documentation: Document IP address and port for operators
  • Updates: Keep QLC+ updated for latest web features

​
Troubleshooting

​
Connection Issues

Can’t connect: Check firewall, port, and IP address Slow updates: Verify network quality, reduce number of widgets WebSocket errors: Check browser console, try different browser

​
Performance Issues

Laggy interface: Reduce update rate, simplify Virtual Console High CPU: Limit active widgets, reduce WebSocket clients Memory usage: Restart Web Access periodically for long-running shows

​
Technical Notes

​
WebSocket Protocol

Messages are JSON-formatted: 
{
  "type": "widgetUpdate",
  "id": 123,
  "property": "value",
  "value": 128
}

​
HTTP Endpoints

  • GET /: Main interface page
  • GET /vc: Virtual Console view
  • GET /simpledesk: Simple Desk view
  • POST /loadProject: Upload project
  • GET /ws: WebSocket upgrade endpoint

​
Browser Compatibility

  • Chrome/Edge: Full support
  • Firefox: Full support
  • Safari: Full support (iOS 11+)
  • Internet Explorer: Not supported

Build docs developers (and LLMs) love

Get started for freeTalk to us