问在C#编码中，事件案例中的前缀"On“实现了什么？

EN

void MoveLookController::OnPointerPressed(
_In_ CoreWindow^ sender,
_In_ PointerEventArgs^ args)
{
    // Get the current pointer position.
    uint32 pointerID = args->CurrentPoint->PointerId;
    DirectX::XMFLOAT2 position = DirectX::XMFLOAT2( args->CurrentPoint->Position.X, args->CurrentPoint->Position.Y );

    auto device = args->CurrentPoint->PointerDevice;
    auto deviceType = device->PointerDeviceType;
    if ( deviceType == PointerDeviceType::Mouse )
    {
        // Action, Jump, or Fire
    }

    // Check  if this pointer is in the move control.
    // Change the values  to percentages of the preferred screen resolution.
    // You can set the x value to <preferred resolution> * <percentage of width>
    // for example, ( position.x < (screenResolution.x * 0.15) ).

    if (( position.x < 300 && position.y > 380 ) && ( deviceType != PointerDeviceType::Mouse ))
    {
        if ( !m_moveInUse ) // if no pointer is in this control yet
        {
            // Process a DPad touch down event.
            m_moveFirstDown = position;                 // Save the location of the initial contact.
            m_movePointerPosition = position;
            m_movePointerID = pointerID;                // Store the id of the pointer using this control.
            m_moveInUse = TRUE;
        }
    }
    else // This pointer must be in the look control.
    {
        if ( !m_lookInUse ) // If no pointer is in this control yet...
        {
            m_lookLastPoint = position;                         // save the point for later move
            m_lookPointerID = args->CurrentPoint->PointerId;  // store the id of pointer using this control
            m_lookLastDelta.x = m_lookLastDelta.y = 0;          // these are for smoothing
            m_lookInUse = TRUE;
        }
    }
}