References ▼
#include "ltwrappr.h"
virtual L_INT LVectorBase::VectorEventProcCallBack(pVector, uLevel, pEvent, pUserData)
Processes each event that occurs inside the vector handle.
Pointer to the vector handle in which the event occurred.
Level of the event that occurred. For a top-level event, this value is 0. For a second level event this value is 1, etc. For an example, refer to the Comments section below.
Pointer to a VECTOREVENT structure that describes the event that occurred in the vector handle.
A void pointer that you can use to access a variable or structure containing data that your callback function needs. This gives you a way to receive data indirectly from the function that uses this callback function.
Keep in mind that this is a void pointer, which must be cast to the appropriate data type within your callback function.
| Value | Meaning |
|---|---|
| SUCCESS | The function was successful. |
| < 1 | An error occurred. Refer to Return Codes. |
To use this function you must derive a class from LVectorBase and override the VectorEventProcCallBack function.
To understand event levels, consider this example:
Assume the clipboard contains a vector handle with 1 layer and 2 objects inside this layer.
Now you execute LVectorBase::CopyFromClipboard, the toolkit may fire these events in the following sequence:
| pEvent->uType | pEvent->Status | uLevel | Comment |
|---|---|---|---|
| VECTOR_EVENT_COPYFROMCLIPBOARD | VECTOR_EVENT_BEFORE | 0 | LVectorBase::CopyFromClipboard is about to execute. |
| VECTOR_EVENT_ADDLAYER | VECTOR_EVENT_BEFORE | 1 | LVectorBase::AddLayer is about to execute. |
| VECTOR_EVENT_ADDOBJECT | VECTOR_EVENT_BEFORE | 2 | LVectorBase::AddObject for first object is about to execute. |
| VECTOR_EVENT_ADDOBJECT | VECTOR_EVENT_AFTER | 2 | LVectorBase::AddObject for first object has been completed. |
| VECTOR_EVENT_ADDOBJECT | VECTOR_EVENT_BEFORE | 2 | LVectorBase::AddObject for second object is about to execute. |
| VECTOR_EVENT_ADDOBJECT | VECTOR_EVENT_AFTER | 2 | LVectorBase::AddObject for second object has been completed. |
| VECTOR_EVENT_ADDLAYER | VECTOR_EVENT_AFTER | 1 | LVectorBase::AddLayer has been completed. |
| VECTOR_EVENT_COPYFROMCLIPBOARD | VECTOR_EVENT_AFTER | 0 | LVectorBase::CopyFromClipboard has been completed. |
Your callback can monitor all these operations and cancels whatever operation you want.
This example defines a new event consisting of a rotate, translate and a scale. A message is displayed in the Event callback before the event and after the event. LVectorBase::Event() VectorEventProcCallBack
#define MY_CUSTOM_EVENT (VECTOR_EVENT_USER+1)class LMyVector2: public LVectorBase{protected:L_INT LMyVector2::VectorEventProcCallBack(pVECTORHANDLE pVector,L_UINT uLevel,pVECTOREVENT pEvent,L_VOID *pUserData);};L_INT LMyVector2::VectorEventProcCallBack(pVECTORHANDLE pVector,L_UINT uLevel,pVECTOREVENT pEvent,L_VOID *pUserData){L_TCHAR *pszMsg= TEXT("");if (pEvent->uType == MY_CUSTOM_EVENT){switch (pEvent->Status){case VECTOR_EVENT_STATUS_BEFORE:pszMsg = TEXT("Before MY_CUSTOM_EVENT");break;case VECTOR_EVENT_STATUS_AFTER:pszMsg = TEXT("After MY_CUSTOM_EVENT");break;}MessageBox(NULL, pszMsg, TEXT(""), MB_OK);}return LVectorBase::VectorEventProcCallBack(pVector, uLevel, pEvent, pUserData);}L_INT LVectorBase__VectorEventProcCallBackExample( LVectorBase *pVector){L_INT nRet = SUCCESS;VECTOREVENT Event;VECTORPOINT Point;// Fire our new event, giving all event callbacks in the vector handle a chance to cancel our operationmemset( &Event, 0, sizeof( Event ) );Event.nSize = sizeof( Event );Event.uType = MY_CUSTOM_EVENT;Event.Status = VECTOR_EVENT_STATUS_BEFORE;nRet = pVector->Event(&Event);if( nRet != SUCCESS ){//a callback has returned something other than success, we should cancelreturn nRet;}// do the operation, for example, rotate, translate and scalePoint.x = 10.0; Point.y = 20.0; Point.z = 30.0;nRet = pVector->SetRotation( &Point);if(nRet != SUCCESS)return nRet;Point.x = 4.0; Point.y = 4.0; Point.z = 4.0;nRet = pVector->SetTranslation(&Point );if(nRet != SUCCESS)return nRet;Point.x = 0.5; Point.y = 0.5; Point.z = 0.5;nRet = pVector->SetScale(&Point );if(nRet != SUCCESS)return nRet;// notify the vector handle that the operation is doneEvent.Status = VECTOR_EVENT_STATUS_AFTER;nRet = pVector->Event(&Event );if(nRet != SUCCESS)return nRet;return SUCCESS;}