3D Graphics Programming with QuickDraw 3D 1.5.4

Accessing Private Data

You may access private data at any time in a class or object with the routines described in this section.

Q3XObjectClass_GetPrivate

You can use the Q3XObjectClass_GetPrivate routine to get the private instance data of an object.



 
void *Q3XObjectClass_GetPrivate(

                     TQ3XObjectClass    objectClass,

                     TQ3Object          targetObject);

objectClass: A class.
targetObject: An object
return value: The class's private data block.

DESCRIPTION

The Q3XObjectClass_GetPrivate routine returns a pointer to a block of instanceSize bytes (where instanceSize is from the objectClass class's previous Q3XObjectHierarchy_RegisterClass call) that contains the private instance data of targetObject. Q3XObjectClass_GetPrivate returns NULL if instanceSize was 0.

The Q3XObjectClass_GetPrivate routine may return NULL if an invalid object or object of the wrong type is passed in, if instanceSize or classSize is 0 in the previous Q3ObjectHierarchy_Register call, or if an invalid target is passed in.

EXAMPLE



 
TQ3Status Q3FooGroup_SetDummy(

    TQ3GroupObject          group,

    float                   dummy)

{

    TFooGroupPrivate *gPriv;



 
    gPriv = Q3XObjectClass_GetPrivate(

            gFooGroupClass,

            group);

    if (gPriv == NULL)

        return kQ3Failure;

    gPriv->dummy = dummy;

    return Q3Shared_Edited(group);

}

Q3XObject_GetClassPrivate

You can use the Q3XObject_GetClassPrivate routine to get private class data from an object.



 
void *Q3XObject_GetClassPrivate(

                     TQ3XObjectClass    objectClass,

                     TQ3Object          targetObject);

objectClass: A class.
targetObject: An object
return value: The class's private data block.

DESCRIPTION

The Q3XObject_GetClassPrivate routine returns a pointer to a block of instanceSize bytes (where instanceSize is from the objectClass class's previous Q3XObjectHierarchy_RegisterClass call) that contains the private class data of targetObject. If instanceSize was 0, Q3XObject_GetClassPrivate returns NULL .

The Q3XObject_GetClassPrivate routine may return NULL if an invalid object or object of the wrong type is passed in, if instanceSize or classSize is 0 in the previous Q3ObjectHierarchy_Register call, or if an invalid target is passed in.

Q3XObjectClass_GetClassPrivate

You can use the Q3XObjectClass_GetClassPrivate routine to get private class data from a class.



 
void *Q3XObjectClass_GetClassPrivate(

                     TQ3XObjectClass    objectClass,

                     TQ3XObjectClass    targetObjectClass);

objectClass: A class.
targetObjectClass: A class.
return value: The target class's private data block.

DESCRIPTION

The Q3XObjectClass_GetClassPrivate routine returns a pointer to a block of instanceSize bytes (where instanceSize is from the objectClass class's previous Q3XObjectHierarchy_RegisterClass call) that contains the private data of targetObject. If instanceSize was 0, Q3XObjectClass_GetClassPrivate returns NULL .

The Q3XObjectClass_GetClassPrivate routine may return NULL if an invalid object or object of the wrong type is passed in, if instanceSize or classSize is 0 in the previous Q3ObjectHierarchy_Register call, or if an invalid target is passed in.