Commands Manual

Table of Contents

• About
• CommandClassInterface
• LegacyCommandClassInterface
• Data
• Calling Commands
• Further Reading

About

maxon::CommandClassInterface is a base interface for standardized commands. Such a command operates solely on the given input data and can be used in various situations.

CommandClassInterface

A custom command must implement these two methods:

• maxon::CommandClassInterface::GetState(): Returns maxon::COMMANDSTATE to indicate if the command can be performed on the given data.
• maxon::CommandClassInterface::Execute(): Executes the command on the given data.

An implementation for such a data object must be based on maxon::CommandDataInterface which in return in based on maxon::DataDictionaryObjectInterface.

Note

All data related to the execution of the command must be stored in the maxon::CommandDataRef object.

Interactive commands (e.g. tools) can also implement maxon::CommandInteractionClassInterface:

• maxon::CommandInteractionClassInterface::Interact(): Executes the command interaction. See maxon::INTERACTIONTYPE.

// This example implements both a command data and a simple command.
 
//------------------------------------------------------------------------------
// Simple data
//------------------------------------------------------------------------------
class ExampleDataImpl : public Component<ExampleDataImpl, CommandDataInterface>
{
  MAXON_COMPONENT(NORMAL, DataDictionaryObjectClass);
 
public:
  MAXON_METHOD Result<void> SetData(ForwardingDataPtr&& key, Data&& data)
  {
    return super.SetData(std::move(key), std::move(data));
  }
 
  MAXON_METHOD Result<Data> GetData(const ConstDataPtr& key) const
  {
    return super.GetData(std::move(key));
  }
};
 
// register data
MAXON_COMPONENT_CLASS_REGISTER(ExampleDataImpl, CommandDataClasses, "net.maxonexample.commanddata.exampledata");
 
//------------------------------------------------------------------------------
// Simple command
//------------------------------------------------------------------------------
class ExampleCommandImpl : public Component<ExampleCommandImpl, CommandClassInterface>
{
  MAXON_COMPONENT();
 
public:
  MAXON_METHOD Result<COMMANDSTATE> GetState(CommandDataRef& data) const
  {
    return maxon::COMMANDSTATE::ENABLED;
  }
 
  MAXON_METHOD Result<COMMANDRESULT> Execute(CommandDataRef& data) const
  {
    iferr_scope;
 
    const COMMANDSTATE commandState = self.GetState(data) iferr_return;
    if (commandState != COMMANDSTATE::ENABLED)
      return COMMANDRESULT::SKIP;
 
    // get data from context
    const maxon::Int32 valueA = data.Get<maxon::Int32>(0) iferr_return;
    const maxon::Int32 valueB = data.Get<maxon::Int32>(1) iferr_return;
 
    // perform command
    const maxon::Int32 res = valueA + valueB;
 
    // store result in the context
    data.Set(2, res) iferr_return;
 
    return maxon::COMMANDRESULT::OK;
  }
};
 
// register command
MAXON_COMPONENT_OBJECT_REGISTER(ExampleCommandImpl, CommandClasses, "net.maxonexample.command.addition");

LegacyCommandClassInterface

Some classic data types like BaseContainer cannot be stored in a maxon::DataDictionary. Therefore a custom data class is needed to store specific custom data. Such a data class can be implemented based on maxon::LegacyCommandDataInterface:

• maxon::LegacyCommandDataInterface::GetLegacyData(): Returns the stored custom data.
• maxon::LegacyCommandDataInterface::SetLegacyData(): Copies the given custom data.

maxon::LegacyCommandClassInterface is based on maxon::CommandClassInterface. It can be implemented if custom data should be handled.

• maxon::LegacyCommandClassInterface::ConvertSettings(): Copies the custom data into the maxon::DataDictionary.

// This example shows a simple data structure to store some pointers.
 
struct MoGraphSetupData
{
  maxon::Result<void> CopyFrom(const MoGraphSetupData& other)
  {
    iferr_scope;
    _doc = other._doc;
    _cloner = other._cloner;
    _object = other._object;
    return maxon::OK;
  }
 
  BaseDocument* _doc = nullptr;     
  BaseObject*   _cloner = nullptr;  
  BaseObject*   _object = nullptr;  
};

// This example shows the implementation of a simple command that handles "legacy" data.
 
//------------------------------------------------------------------------------
// MoGraph setup data
//------------------------------------------------------------------------------
class MoGraphSetupDataImpl : public Component<MoGraphSetupDataImpl, LegacyCommandDataInterface>
{
  MAXON_COMPONENT(NORMAL, DataDictionaryObjectClass);
 
public:
 
 
  MAXON_METHOD Int GetLegacyDataCount() const
  {
    return 1;
  }
 
  MAXON_METHOD Result<Generic*> GetLegacyData(Int index)
  {
    Generic* const dtaPtr = reinterpret_cast<Generic*>(&_data);
    return dtaPtr;
  }
 
  MAXON_METHOD Result<void> SetLegacyData(const Generic* data, Int index)
  {
    iferr_scope;
 
    if (data == nullptr)
      return maxon::NullptrError(MAXON_SOURCE_LOCATION);
 
    const MoGraphSetupData* const moGraphData = reinterpret_cast<const MoGraphSetupData*>(data);
    _data.CopyFrom(*moGraphData) iferr_return;
    return OK;
  }
 
  MAXON_METHOD Result<void> SetData(ForwardingDataPtr&& key, Data&& data)
  {
    return super.SetData(std::move(key), std::move(data));
  }
 
  MAXON_METHOD Result<Data> GetData(const ConstDataPtr& key) const
  {
    return super.GetData(std::move(key));
  }
 
private:
  MoGraphSetupData _data; 
};
 
//------------------------------------------------------------------------------
// register data
//------------------------------------------------------------------------------
MAXON_COMPONENT_CLASS_REGISTER(MoGraphSetupDataImpl, LegacyCommandDataClasses, "net.maxonexample.legacycommanddata.mographsetup");
 
//------------------------------------------------------------------------------
// MoGraph setup command. Creates a cloner and uses the given object as input.
//------------------------------------------------------------------------------
class MoGraphSetupCommandImpl : public Component<MoGraphSetupCommandImpl, CommandClassInterface>
{
  MAXON_COMPONENT();
 
public:
  MAXON_METHOD Result<COMMANDSTATE> GetState(CommandDataRef& data) const
  {
    return maxon::COMMANDSTATE::ENABLED;
  }
 
  MAXON_METHOD Result<COMMANDRESULT> Execute(CommandDataRef& data) const
  {
    iferr_scope;
 
    const COMMANDSTATE commandState = self.GetState(data) iferr_return;
    if (commandState != COMMANDSTATE::ENABLED)
      return COMMANDRESULT::SKIP;
 
    // get and check input data
    LegacyCommandDataRef legacyData = Cast<LegacyCommandDataRef>(data);
    const maxon::Int dataIndex = 0;
    MoGraphSetupData&       moData = legacyData.GetLegacyData<MoGraphSetupData>(dataIndex) iferr_return;
    if (moData._doc == nullptr)
      return maxon::NullptrError(MAXON_SOURCE_LOCATION);
 
    // check for object
    if (moData._object == nullptr)
    {
      // if no object is given, use the active object
      BaseObject* const activeObject = moData._doc->GetActiveObject();
      // if no object is active, there is nothing to do
      if (activeObject == nullptr)
        return COMMANDRESULT::SKIP;
 
      moData._object = activeObject;
    }
 
    // create cloner
    BaseObject* const cloner = BaseObject::Alloc(1018544);
    if (cloner == nullptr)
      return maxon::OutOfMemoryError(MAXON_SOURCE_LOCATION);
 
    moData._doc->InsertObject(cloner, nullptr, nullptr);
    // place the object under the cloner
    moData._object->Remove();
    moData._doc->InsertObject(moData._object, cloner, nullptr);
 
    // store result
    moData._cloner = cloner;
 
    return maxon::COMMANDRESULT::OK;
  }
};
 
//------------------------------------------------------------------------------
// register command
//------------------------------------------------------------------------------
MAXON_COMPONENT_OBJECT_REGISTER(MoGraphSetupCommandImpl, CommandClasses, "net.maxonexample.command.mographsetup");

Data

The data a command operates on is stored in a data object. A default data implementation is stored at maxon::CommandDataClasses::BASE. A custom data class can be implemented based on:

• maxon::CommandDataInterface: A base data interface. Based on maxon::DataDictionaryObjectInterface.
• maxon::LegacyCommandDataInterface: Data for maxon::LegacyCommandClassInterface. See above.

Calling Commands

A given command can be executed by calling the "Invoke" of the data object.

// This example shows the declarations of published objects
// giving access to the data and command implementations
 
namespace CommandDataClasses
{
  // example data
  MAXON_DECLARATION(CommandDataClasses::EntryType, EXAMPLEDATA, "net.maxonexample.commanddata.exampledata");
}
 
namespace CommandClasses
{
  // example command
  MAXON_DECLARATION(CommandClasses::EntryType, EXAMPLE, "net.maxonexample.command.addition");
  // MoGraph setup command. Must be used with MOGRAPHSETUPDATA.
  MAXON_DECLARATION(CommandClasses::EntryType, MOGRAPHSETUP, "net.maxonexample.command.mographsetup");
}
 
namespace LegacyCommandDataClasses
{
  // MoGraph setup data for MOGRAPHSETUP command
  MAXON_DECLARATION(LegacyCommandDataClasses::EntryType, MOGRAPHSETUPDATA, "net.maxonexample.legacycommanddata.mographsetup");
}

  // This example creates an example data and calls the example command.
 
  // create data
  maxon::CommandDataRef data = maxon::CommandDataClasses::EXAMPLEDATA().Create() iferr_return;
  data.Set(0, maxon::Int32(100)) iferr_return;
  data.Set(1, maxon::Int32(200)) iferr_return;
 
  // invoke command
  const auto command = maxon::CommandClasses::EXAMPLE();
  const maxon::COMMANDRESULT res = data.Invoke(command, false) iferr_return;
  if (res != maxon::COMMANDRESULT::OK)
    return maxon::OK;
 
  // get result
  const maxon::Int32 resultValue = data.Get<maxon::Int32>(2) iferr_return;
  DiagnosticOutput("Result: @", resultValue);

  // This example creates a specific data for the given command,
  // calls that command and receives the resulting object.
 
  // prepare mograph data
  // no object is set; the active object of the given document should be used
  MoGraphSetupData data;
  data._doc = doc;
  data._object = nullptr;
  const maxon::Int dataIndex = 0;
 
  // create data
  maxon::LegacyCommandDataRef legacyData = maxon::LegacyCommandDataClasses::MOGRAPHSETUPDATA().Create() iferr_return;
  legacyData.SetLegacyData<MoGraphSetupData>(data, dataIndex) iferr_return;
 
  // invoke command
  const auto command = maxon::CommandClasses::MOGRAPHSETUP();
  const maxon::COMMANDRESULT res = legacyData.Invoke(command, false) iferr_return;
  if (res != maxon::COMMANDRESULT::OK)
    return maxon::OK;
 
  // get result
  const MoGraphSetupData result = legacyData.GetLegacyData<MoGraphSetupData>(dataIndex) iferr_return;
  result._cloner->SetName("The New Cloner"_s);

Further Reading

• MAXON API Base Classes
• MAXON API Interfaces
• Published Objects
• Initialization
• ExecutionInterface Manual