Picking Text Dots

This brief guide demonstrates how to interactively select Text Dot objects with C/C++ CRhinoGetObject.

Problem

Imagine you would like to allow the user to interactively select text dot objects from my plugin command. The first place you might look is the CRhinoGetObject class, for a text dot geometry filter. This does not exist. So, how to go about this?

Solution

If CRhinoGetObject does not have filters to select what you want, then simply derive a new class from CRhinoGetObject and override the CustomGeometryFilter virtual function. From within this function, simply return true if the object meets your selection criteria.

Sample

The following example code demonstrates how to derive a new class from CRhinoGetObject and override the CustomGeometryFilter virtual function in order to allow for selection of just text dot objects. That is, those objects whose geometry member is ON_TextDot

class CGetTextDotObject : public CRhinoGetObject
{
  bool CustomGeometryFilter(
const CRhinoObject* object,
const ON_Geometry* geometry,
ON_COMPONENT_INDEX component_index
) const;
};

bool CGetTextDotObject::CustomGeometryFilter(
    const CRhinoObject* object,
    const ON_Geometry* geometry,
    ON_COMPONENT_INDEX component_index
    ) const
{
  bool rc = false;
  if( geometry )
  {
    const ON_TextDot* p = ON_TextDot::Cast( geometry );
    if( p )
      rc = true;
  }
  return rc;
}

The following example code demonstrates how you can use the new class…

CRhinoCommand::result CCommandTest::RunCommand( const CRhinoCommandContext& context )
{
  CGetTextDotObject go;
  go.SetCommandPrompt( L"Select text dots" );
  go.GetObjects( 1, 0 );
  if( go.CommandResult() != success )
    return go.CommandResult();

  const int object_count = go.ObjectCount();
  int i;
  for( i = 0; i < object_count; i++ )
  {
    const ON_TextDot* p = ON_TextDot::Cast( go.Object(i).Geometry() );
    if( p )
    {
      ON_wString sPoint;
      RhinoFormatPoint( p->m_point, sPoint );
      RhinoApp().Print( L"TextDot%d: point = (%s), text = \"%s\"\n",
  i, sPoint, p->m_text );
    }
  }

  return success;
}