Fixtures API

Fixtures represent physical lighting devices in QLC+. This guide covers the Fixture class, fixture definitions, and related APIs.

Fixture Class

The Fixture class (engine/src/fixture.h:71) represents an instance of a lighting fixture.

Creating Fixtures

Fixture* fixture = new Fixture(doc);
fixture->setName("My Moving Head");
fixture->setUniverse(0);
fixture->setAddress(0);
fixture->setChannels(16);

// Add to document
doc->addFixture(fixture);

Basic Properties

Identity
Addressing
Definition

// ID (assigned by Doc)
void setID(quint32 id);
quint32 id() const;
static quint32 invalidId();

// Name
void setName(const QString& name);
QString name() const;

// Type
enum Type {
    Dimmer = 0,
    MovingHead,
    Scanner,
    RGBPanel,
    GenericRGB
};
int type() const;

// Universe
void setUniverse(quint32 universe);
quint32 universe() const;

// DMX address (0-511)
void setAddress(quint32 address);
quint32 address() const;

// Combined universe and address
quint32 universeAddress() const;

// Number of channels
void setChannels(quint32 channels);
quint32 channels() const;

// Check for address conflict
bool checkAddressValidity() const;

// Fixture definition
QLCFixtureDef* fixtureDef() const;

// Fixture mode
QLCFixtureMode* fixtureMode() const;
QString fixtureModeName() const;

// Set from definition
bool setFixtureDefinition(const QLCFixtureDef* fixtureDef,
                         const QLCFixtureMode* mode);

Channel Access

// Get channel
const QLCChannel* channel(quint32 channelIndex) const;

// Get channel by group
QLCChannel::Group channelGroup(quint32 channelIndex) const;

// Find channel number by group
uint32_t channelNumber(QLCChannel::Group group,
                      QLCChannel::ControlByte controlByte) const;

// Master intensity channel
QLCChannel* masterIntensityChannel() const;

// All channels
QVector<const QLCChannel*> channels() const;

Channel Groups

namespace QLCChannel
{
    enum Group {
        NoGroup = 0,
        Intensity,
        Colour,
        Gobo,
        Shutter,
        Speed,
        Pan,
        Tilt,
        Prism,
        Beam,
        Effect,
        Maintenance,
        Nothing
    };
    
    enum ControlByte {
        MSB = 0,  // Most significant byte (coarse)
        LSB = 1   // Least significant byte (fine)
    };
}

Heads

Multi-head fixtures (e.g., LED bars) have multiple heads:

// Get heads
int headsCount() const;
QLCFixtureHead head(int index) const;

// Head information
class QLCFixtureHead
{
public:
    // Channels in this head
    QVector<quint32> channels() const;
    
    // RGB/CMY components
    QVector<quint32> rgbChannels() const;
    QVector<quint32> cmyChannels() const;
    
    // Master dimmer
    int masterIntensityChannel() const;
};

Physical Properties

class QLCPhysical
{
public:
    // Bulb
    QString bulbType() const;
    int bulbLumens() const;
    int bulbColourTemperature() const;
    
    // Dimensions
    int weight() const;      // kg
    int width() const;       // mm
    int height() const;      // mm
    int depth() const;       // mm
    
    // Lens
    QString lensName() const;
    int lensDegreesMin() const;
    int lensDegreesMax() const;
    
    // Focus
    enum FocusType { Fixed, Head, Mirror };
    FocusType focusType() const;
    int focusPanMax() const;   // degrees
    int focusTiltMax() const;  // degrees
    
    // Technical
    int powerConsumption() const;  // watts
    QString dmxConnector() const;
};

QLCPhysical physical() const;

Load and Save

// Load from XML
bool loadXML(QXmlStreamReader& doc, const QLCFixtureDefCache* cache);

// Save to XML
bool saveXML(QXmlStreamWriter* doc) const;

Signals:

void changed(quint32 id);

Fixture Definitions

Fixture definitions describe fixture capabilities.

QLCFixtureDef Class

class QLCFixtureDef
{
public:
    // Identity
    QString manufacturer() const;
    QString model() const;
    QString name() const;  // "Manufacturer Model"
    QString type() const;
    
    // Channels
    QVector<QLCChannel*> channels() const;
    QLCChannel* channel(const QString& name) const;
    
    // Modes
    QVector<QLCFixtureMode*> modes() const;
    QLCFixtureMode* mode(const QString& name) const;
    
    // Creator
    QString author() const;
};

QLCFixtureMode Class

class QLCFixtureMode
{
public:
    // Name
    QString name() const;
    
    // Channels
    int channels() const;
    QLCChannel* channel(quint32 index) const;
    quint32 channelNumber(QLCChannel* channel) const;
    
    // Physical properties
    QLCPhysical physical() const;
    
    // Heads
    int heads() const;
    QLCFixtureHead head(int index) const;
};

QLCChannel Class

class QLCChannel
{
public:
    // Name and group
    QString name() const;
    Group group() const;
    ControlByte controlByte() const;
    
    // Color (for intensity channels)
    QColor colour() const;
    
    // Capabilities
    QList<QLCCapability*> capabilities() const;
    QLCCapability* searchCapability(uchar value) const;
    QLCCapability* searchCapability(const QString& name) const;
    
    // Default value
    uchar defaultValue() const;
};

QLCCapability Class

class QLCCapability
{
public:
    // Value range
    uchar min() const;
    uchar max() const;
    uchar middle() const;
    
    // Name and description
    QString name() const;
    
    // Resources
    QString resourceName() const;
    QColor resourceColor1() const;
    QColor resourceColor2() const;
    
    // Aliases
    QString alias(const QString& capability) const;
};

Fixture Definition Cache

The cache loads and manages fixture definitions.

QLCFixtureDefCache Class

class QLCFixtureDefCache
{
public:
    // Load definitions
    bool load(const QString& path);
    int loadMap(const QString& path);
    
    // Access definitions
    QList<QLCFixtureDef*> definitions() const;
    QLCFixtureDef* fixtureDef(const QString& manufacturer,
                             const QString& model) const;
    
    // Manufacturers
    QStringList manufacturers() const;
    QStringList models(const QString& manufacturer) const;
};

// Access from Doc
QLCFixtureDefCache* cache = doc->fixtureDefCache();

Working with Fixtures

Adding a Generic RGB Fixture

Fixture* createGenericRGB(Doc* doc, const QString& name,
                         quint32 universe, quint32 address)
{
    Fixture* fixture = new Fixture(doc);
    fixture->setName(name);
    fixture->setUniverse(universe);
    fixture->setAddress(address);
    fixture->setChannels(3);  // RGB
    
    if (!doc->addFixture(fixture))
    {
        delete fixture;
        return nullptr;
    }
    
    return fixture;
}

Adding a Fixture from Definition

Fixture* createFromDefinition(Doc* doc, const QString& manufacturer,
                             const QString& model, const QString& mode,
                             const QString& name,
                             quint32 universe, quint32 address)
{
    // Get definition
    QLCFixtureDefCache* cache = doc->fixtureDefCache();
    QLCFixtureDef* fixtureDef = cache->fixtureDef(manufacturer, model);
    if (!fixtureDef)
        return nullptr;
    
    // Get mode
    QLCFixtureMode* fixtureMode = fixtureDef->mode(mode);
    if (!fixtureMode)
        return nullptr;
    
    // Create fixture
    Fixture* fixture = new Fixture(doc);
    fixture->setName(name);
    fixture->setUniverse(universe);
    fixture->setAddress(address);
    fixture->setFixtureDefinition(fixtureDef, fixtureMode);
    
    if (!doc->addFixture(fixture))
    {
        delete fixture;
        return nullptr;
    }
    
    return fixture;
}

Enumerating Fixture Channels

void printFixtureChannels(Fixture* fixture)
{
    qDebug() << "Fixture:" << fixture->name();
    qDebug() << "Universe:" << fixture->universe()
             << "Address:" << fixture->address();
    qDebug() << "Channels:" << fixture->channels();
    
    for (quint32 i = 0; i < fixture->channels(); i++)
    {
        const QLCChannel* ch = fixture->channel(i);
        if (ch)
        {
            qDebug() << "  Channel" << i << ":"
                     << ch->name() << "("
                     << QLCChannel::groupToString(ch->group())
                     << ")";
        }
    }
}

Finding Specific Channels

// Find pan channel
quint32 panChannel = fixture->channelNumber(QLCChannel::Pan,
                                           QLCChannel::MSB);
if (panChannel != QLCChannel::invalid())
{
    qDebug() << "Pan channel:" << panChannel;
}

// Find tilt channel
quint32 tiltChannel = fixture->channelNumber(QLCChannel::Tilt,
                                            QLCChannel::MSB);
if (tiltChannel != QLCChannel::invalid())
{
    qDebug() << "Tilt channel:" << tiltChannel;
}

// Find RGB channels
QLCFixtureHead head = fixture->head(0);
QVector<quint32> rgb = head.rgbChannels();
if (rgb.size() >= 3)
{
    qDebug() << "Red:" << rgb[0]
             << "Green:" << rgb[1]
             << "Blue:" << rgb[2];
}

Checking Address Conflicts

bool hasConflict(Doc* doc, Fixture* fixture)
{
    quint32 startAddr = fixture->universeAddress();
    quint32 endAddr = startAddr + fixture->channels() - 1;
    
    for (Fixture* other : doc->fixtures())
    {
        if (other->id() == fixture->id())
            continue;
            
        quint32 otherStart = other->universeAddress();
        quint32 otherEnd = otherStart + other->channels() - 1;
        
        // Check for overlap
        if (!(endAddr < otherStart || startAddr > otherEnd))
        {
            qWarning() << "Conflict between" << fixture->name()
                      << "and" << other->name();
            return true;
        }
    }
    
    return false;
}

Fixture Groups

Fixture groups organize fixtures for RGB matrix effects.

FixtureGroup Class

class FixtureGroup
{
public:
    // Identity
    void setName(const QString& name);
    QString name() const;
    
    // Size
    void setSize(const QSize& size);
    QSize size() const;
    
    // Heads
    struct GroupHead {
        quint32 fxi;   // Fixture ID
        int head;      // Head index
    };
    
    void assignHead(QPoint pt, GroupHead head);
    void resetHead(QPoint pt);
    GroupHead head(QPoint pt) const;
    
    // Get all heads
    QList<quint32> fixtureList() const;
    QList<GroupHead> headsList() const;
};

Creating a Fixture Group

FixtureGroup* createMatrixGroup(Doc* doc, const QString& name,
                               int width, int height,
                               const QList<quint32>& fixtureIds)
{
    FixtureGroup* group = new FixtureGroup(doc);
    group->setName(name);
    group->setSize(QSize(width, height));
    
    // Assign fixtures to grid positions
    int idx = 0;
    for (int y = 0; y < height; y++)
    {
        for (int x = 0; x < width; x++)
        {
            if (idx < fixtureIds.size())
            {
                FixtureGroup::GroupHead head;
                head.fxi = fixtureIds[idx++];
                head.head = 0;
                group->assignHead(QPoint(x, y), head);
            }
        }
    }
    
    doc->addFixtureGroup(group);
    return group;
}

Channel Modifiers

Channel modifiers apply transformations to channel values.

ChannelModifier Class

class ChannelModifier
{
public:
    // Name
    QString name() const;
    
    // Apply modification
    uchar modifyValue(uchar value) const;
    
    // Template
    QString templateName() const;
};

Using Modifiers

// Get modifiers cache
QLCModifiersCache* cache = doc->modifiersCache();

// Get modifier
ChannelModifier* modifier = cache->modifier("MyModifier");

// Apply to value
uchar original = 128;
uchar modified = modifier->modifyValue(original);

Advanced Topics

Cross-Universe Fixtures

Fixtures can span multiple universes:

Fixture* fixture = new Fixture(doc);
fixture->setUniverse(0);
fixture->setAddress(500);  // Starts at address 500
fixture->setChannels(20);  // Spans into next universe

// Add with cross-universe flag
doc->addFixture(fixture, Fixture::invalidId(), true);

Forced HTP/LTP

Override default channel behavior:

QList<int> forcedHTP;
QList<int> forcedLTP;

forcedHTP << 0 << 1 << 2;  // Force RGB channels to HTP
forcedLTP << 5;             // Force gobo channel to LTP

doc->updateFixtureChannelCapabilities(fixture->id(),
                                     forcedHTP, forcedLTP);

Bulk Fixture Operations

// Replace all fixtures
QList<Fixture*> newFixtures;
// ... populate newFixtures ...
doc->replaceFixtures(newFixtures);

// Get total power consumption
int fuzzy = 0;
int totalWatts = doc->totalPowerConsumption(fuzzy);
qDebug() << "Total:" << totalWatts << "W"
         << "Fixtures without power data:" << fuzzy;

Best Practices

Memory Management

Fixtures are owned by Doc
Use Doc::addFixture() and Doc::deleteFixture()
Don’t delete fixtures manually
Use QPointer<Fixture> for long-lived references

Address Management

Always check for address conflicts
Use checkAddressValidity() before adding
Consider cross-universe fixtures
Leave gaps between fixtures for patching flexibility

Channel Access

Always check if channel exists before using
Use QLCChannel::invalid() constant for comparisons
Cache channel lookups if used frequently
Handle multi-head fixtures correctly

Fixture Definitions

Load fixture definition cache at startup
Prefer using definitions over generic fixtures
Validate definition exists before creating fixture
Handle missing definitions gracefully

Building & Contributing

API Reference

Fixture Development

Fixtures API

Fixture Class

Creating Fixtures

Basic Properties

Channel Access

Channel Groups

Heads

Physical Properties

Load and Save

Fixture Definitions

QLCFixtureDef Class

QLCFixtureMode Class

QLCChannel Class

QLCCapability Class

Fixture Definition Cache

QLCFixtureDefCache Class

Working with Fixtures

Adding a Generic RGB Fixture

Adding a Fixture from Definition

Enumerating Fixture Channels

Finding Specific Channels

Checking Address Conflicts

Fixture Groups

FixtureGroup Class

Creating a Fixture Group

Channel Modifiers

ChannelModifier Class

Using Modifiers

Advanced Topics

Cross-Universe Fixtures

Forced HTP/LTP

Bulk Fixture Operations

Best Practices

Resources

Build docs developers (and LLMs) love

Building & Contributing

API Reference

Fixture Development

​Fixture Class

​Creating Fixtures

​Basic Properties

​Channel Access

​Channel Groups

​Heads

​Physical Properties

​Load and Save

​Fixture Definitions

​QLCFixtureDef Class

​QLCFixtureMode Class

​QLCChannel Class

​QLCCapability Class

​Fixture Definition Cache

​QLCFixtureDefCache Class

​Working with Fixtures

​Adding a Generic RGB Fixture

​Adding a Fixture from Definition

​Enumerating Fixture Channels

​Finding Specific Channels

​Checking Address Conflicts

​Fixture Groups

​FixtureGroup Class

​Creating a Fixture Group

​Channel Modifiers

​ChannelModifier Class

​Using Modifiers

​Advanced Topics

​Cross-Universe Fixtures

​Forced HTP/LTP

​Bulk Fixture Operations

​Best Practices

​Resources

Build docs developers (and LLMs) love

Fixture Class

Creating Fixtures

Basic Properties

Channel Access

Channel Groups

Heads

Physical Properties

Load and Save

Fixture Definitions

QLCFixtureDef Class

QLCFixtureMode Class

QLCChannel Class

QLCCapability Class

Fixture Definition Cache

QLCFixtureDefCache Class

Working with Fixtures

Adding a Generic RGB Fixture

Adding a Fixture from Definition

Enumerating Fixture Channels

Finding Specific Channels

Checking Address Conflicts

Fixture Groups

FixtureGroup Class

Creating a Fixture Group

Channel Modifiers

ChannelModifier Class

Using Modifiers

Advanced Topics

Cross-Universe Fixtures

Forced HTP/LTP

Bulk Fixture Operations

Best Practices

Resources