The COUNT sample demonstrates how to create a full control and a simple object, within the same DLL, that communicate with each other. The COUNTCTN sample is a simple dialog box application that provides a container for the CCount control.
The CCountCtnDlg dialog box class has two public variables, m_Counter, which is a CCounter object, and m_nMaxCounter which is an integer that's initialized to 10 in CCountCtnDlg's constructor.
CCounter is a full control. In addition to IUnknown and IDispatch, it implements the ICounter interface, which exposes three methods. It supports a dual interface, so you can either access the ICounter methods through IDispatch::Invoke or call them directly by way of the vtable. These methods are SetMaxCounter, StartCounting, and GetInfoFromCounter. CCounter also has one protected data member, called m_pIObject, which is a pointer to the IObject1 interface on a CObject1 object.
CObject1 is a simple object. It also supports a dual interface. In addition to IUnknown and IDispatch, it implements the IObject1 interface, which exposes three methods. These methods are Initialize, SetMax, and Start. CObject1 has two protected data members. The m_pICounter data member contains a back-pointer to the ICounter interface on the CCounter control that instantiates it. The m_nMax data member is an integer.
The CCounter constructor instantiates a CObject1 object and queries for a pointer to its IObject1 interface, which the CCounter control assigns to its m_pIObject data member. It then calls IObject1::Initialize, passing a back-pointer to itself, which the IObject1 object assigns to its m_pICounter data member.
When a user enters a number between 1 and 15 in the dialog box's edit control, the number is assigned to CCountCtnDlg::m_nMaxCounter. When the user taps the Apply button, CCountCtnDlg::OnSetMaxCounter invokes ICounter::SetMaxCounter on the CCounter control, passing the value of m_nMaxCounter as the argument. The ICounter::SetMaxCounter method invokes IObject1::SetMax on its m_pIObject member, passing along the value it was passed. IObject1::SetMax assigns this value to its m_nMax data member.
When a user taps the Start button, CCountCtnDlg::OnStart invokes ICounter::StartCounting on the CCounter control. ICounter::StartCounting invokes IObject::Start on its m_pIObject member, which loops m_nMax times. Each time through the loop, it calls ICounter::GetInfoFromCounter, using the back-pointer stored in its m_pICounter member, passing in a text string that states the number of times it's been through the loop. ICounter::GetInfoFromCounter displays the text string in its window on the dialog box.
This sample demonstrates the following keywords:
You can find the COUNT project files in the Wce\Samples\Atl\COUNT directory.
You can find the COUNTCTN project files in the Wce\Samples\Atl\COUNTCTN directory.
To build the COUNT and COUNTCTN samples, follow the procedure described in Building the Sample Applications, selecting one or more of the following project configurations.