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copied!<p>Here is a <em>breif summary</em> of the code I use to do this in the <a href="http://www.zeusedit.com" rel="noreferrer">Zeus</a> programmer's editor:</p> <p><strong>Step 1:</strong> Define a couple of message structure to hold the Windows message details:</p> <pre><code>typedef struct { MSG msg; LRESULT lResult; } xMessage; struct xWM_COMMAND { HWND hwnd; UINT Msg; WORD ItemID; WORD NotifyCode; HWND Ctl; LRESULT lResult; }; //-- unpack a message buffer #define MSG_UNPACK(var, id, msg) x##id *var = (x##id *)(msg); </code></pre> <p><strong>Step 2:</strong> Define a base window class with a few special methods:</p> <pre><code>class xWindow { protected: //-- windows callback function static LRESULT CALLBACK wndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam); //-- a message dispatch method void dispatch(HWND hwnd, UINT uMessageID, WPARAM wParam, LPARAM lParam, LRESULT &Result); //-- method for command message dispatching virtual void dispatchToCmdMap(xMessage *pMessage); //-- method for windows message dispatching virtual void dispatchToMsgMap(xMessage *pMessage); }; </code></pre> <p><strong>Step 3:</strong> Define a few macros to do the dispatching of the Windows messages:</p> <pre><code>#define BEGIN_MSG_MAP \ protected: \ virtual void dispatchToMsgMap(xMessage *msg)\ { \ if (msg->msg.message == WM_NULL) \ { \ return; \ } #define MSG_HANDLER(meth, wm_msg) \ else if (msg->msg.message == wm_msg) \ { \ this->meth(msg); \ return; \ } #define END_MSG_MAP(base) \ else if (msg->msg.message == WM_COMMAND) \ { \ this->dispatchToCmdMap(msg); \ return; \ } \ else if (msg->msg.message == WM_NOTIFY) \ { \ this->dispatchToNotifyMap(msg); \ return; \ } \ \ base::dispatchToMsgMap(msg); \ }; #define BEGIN_CMD_MAP \ virtual void dispatchToCmdMap(xMessage *msg)\ { \ MSG_UNPACK(Cmd, WM_COMMAND, msg); \ \ if (Cmd->ItemID == 0) \ { \ /* not allowed */ \ } #define CMD_HANDLER(meth, cmd_id) \ else if (Cmd->ItemID == cmd_id) \ { \ this->meth(Cmd->ItemID); \ } #define END_CMD_MAP(base) \ else \ { \ base::dispatchToCmdMap(msg); \ } \ }; </code></pre> <p><strong>Step 4:</strong> Define the dispatcher method:</p> <pre><code>void xWindow::dispatch(HWND, UINT uMessageID, WPARAM wParam, LPARAM lParam, LRESULT &Result) { xMessage message; //-- build up a message packet message.msg.message = uMessageID; message.msg.wParam = wParam; message.msg.lParam = lParam; message.lResult = 0; //-- dispatch the message this->dispatchToMsgMap(&message); } </code></pre> <p><strong>Step 5:</strong> Define the static window procedure method (<strong>NOTE:</strong> this method will need to be used as the Window procedure of the window class when the class is first registered):</p> <pre><code>LRESULT CALLBACK xWindow::wndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam) { LRESULT lResult = 0; //-- look for the creation message if (msg == WM_NCCREATE) { CREATESTRUCT *pCreateData = (CREATESTRUCT*)lParam; //-- get the window object passed in xWindow *pWindow = (xWindow)pCreateData->lpCreateParams; if (pWindow) { //-- attach the window object to the hwnd SetWindowLong(hwnd, pWindow); //-- let the window object dispatch the message pWindow->dispatch(hwnd, msg, wParam, lParam, lResult); } else { //-- leave the message to windows lResult = DefWindowProc(hwnd, msg, wParam, lParam); } } else if (hwnd) { //-- get the object attached to the hwnd xWindow *pWindow = (xWindow *)GetWindowLong(hwnd); //-- check to see if we have an object window attached to the handle if (pWindow) { //-- let the window object dispatch the message pWindow->dispatch(hwnd, msg, wParam, lParam, lResult); } else { //-- leave the message to windows lResult = ::DefWindowProc(hwnd, msg, wParam, lParam); } } return lResult; } </code></pre> <p>Now, using this <em>base class</em> it is possible to define a new window class that will look like this:</p> <pre><code>class MyWindow : public xWindow { protected: //-- the WM_COMMAND message handlers virtual void onAdd(int); virtual void onDelete(int); //-- the WM_CLOSE message handler virtual void onClose(xMessage *pMessage); //-- the WM_SIZE message handler virtual void onSize(xMessage *pMessage); public: //-- ctor and dtor MyWindow(); virtual ~MyWindow(); BEGIN_MSG_MAP //-- command message handlers CMD_HANDLER(onAdd , IDPB_ADD ) CMD_HANDLER(onDelete, IDPB_DELETE) //-- other message handling MSG_HANDLER(onClose , WM_CLOSE) MSG_HANDLER(onSize , WM_SIZE ) END_MSG_MAP(xWindow) }; </code></pre> <p><strong>Edit: How this code works.</strong></p> <p>The secret to understanding how this code works is to remember the <em>wndProc</em> in the <em>xWindow</em> class is nothing but a <em>Win32</em> Window procedure passed to <em>RegisterClassEx</em> when the Win32 Window is registered. </p> <p>Now if you look at the <em>wndProc</em> code you will see it does a bit of setting up and checking but generally it does nothing more than send the Windows message to the <em>dispatch</em> method. </p> <p>The <em>dispatch</em> method is even simpler as it does nothing more than pack the Windows message into an <em>easy to move</em> structure and then sends it off to the <em>dispatchToMsgMap</em> method.</p> <p>Now look at the <em>MyWindow</em> class an you will see this code:</p> <pre><code>BEGIN_MSG_MAP //-- command message handlers CMD_HANDLER(onAdd , IDPB_ADD ) CMD_HANDLER(onDelete, IDPB_DELETE) //-- other message handling MSG_HANDLER(onClose , WM_CLOSE) MSG_HANDLER(onSize , WM_SIZE ) END_MSG_MAP(xWindow) </code></pre> <p>This code is just using the macros defined earlier. If you take a close look at these macros you will see the code above is in fact creating a <em>dispatchToMsgMap</em> method. This is the exact same <em>dispatchToMsgMap</em> method that was called by the <em>dispatch</em> method. </p> <p>I know this method of handling Windows messages does work as I use this exact same approach in the <a href="http://www.zeusedit.com" rel="noreferrer">Zeus for Windows</a> editor.</p>

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