\nI think it’s time to update the scratch program we’ve been\nusing for the past year.\nI hear there’s this new language called C++ that’s going to become\nreally popular any day now,\nso let’s hop on the bandwagon!\n<\/p>\n
\n#define STRICT\n#define UNICODE\n#define _UNICODE\n#include <windows.h>\n#include <windowsx.h>\n#include <ole2.h>\n#include <commctrl.h>\n#include <shlwapi.h>\n#include <shlobj.h>\n#include <shellapi.h>\nHINSTANCE g_hinst;\nclass Window\n{\npublic:\n HWND GetHWND() { return m_hwnd; }\nprotected:\n virtual LRESULT HandleMessage(\n UINT uMsg, WPARAM wParam, LPARAM lParam);\n virtual void PaintContent(PAINTSTRUCT *pps) { }\n virtual LPCTSTR ClassName() = 0;\n virtual BOOL WinRegisterClass(WNDCLASS *pwc)\n { return RegisterClass(pwc); }\n virtual ~Window() { }\n HWND WinCreateWindow(DWORD dwExStyle, LPCTSTR pszName,\n DWORD dwStyle, int x, int y, int cx, int cy,\n HWND hwndParent, HMENU hmenu)\n {\n Register();\n return CreateWindowEx(dwExStyle, ClassName(), pszName, dwStyle,\n x, y, cx, cy, hwndParent, hmenu, g_hinst, this);\n }\nprivate:\n void Register();\n void OnPaint();\n void OnPrintClient(HDC hdc);\n static LRESULT CALLBACK s_WndProc(HWND hwnd,\n UINT uMsg, WPARAM wParam, LPARAM lParam);\nprotected:\n HWND m_hwnd;\n};\nvoid Window::Register()\n{\n WNDCLASS wc;\n wc.style = 0;\n wc.lpfnWndProc = Window::s_WndProc;\n wc.cbClsExtra = 0;\n wc.cbWndExtra = 0;\n wc.hInstance = g_hinst;\n wc.hIcon = NULL;\n wc.hCursor = LoadCursor(NULL, IDC_ARROW);\n wc.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);\n wc.lpszMenuName = NULL;\n wc.lpszClassName = ClassName();\n WinRegisterClass(&wc);\n}\nLRESULT CALLBACK Window::s_WndProc(\n HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)\n{\n Window *self;\n if (uMsg == WM_NCCREATE) {\n LPCREATESTRUCT lpcs = reinterpret_cast<LPCREATESTRUCT>(lParam);\n self = reinterpret_cast<Window *>(lpcs->lpCreateParams);\n self->m_hwnd = hwnd;\n SetWindowLongPtr(hwnd, GWLP_USERDATA,\n reinterpret_cast<LPARAM>(self));\n } else {\n self = reinterpret_cast<Window *>\n (GetWindowLongPtr(hwnd, GWLP_USERDATA));\n }\n if (self) {\n return self->HandleMessage(uMsg, wParam, lParam);\n } else {\n return DefWindowProc(hwnd, uMsg, wParam, lParam);\n }\n}\nLRESULT Window::HandleMessage(\n UINT uMsg, WPARAM wParam, LPARAM lParam)\n{\n LRESULT lres;\n switch (uMsg) {\n case WM_NCDESTROY:\n lres = DefWindowProc(m_hwnd, uMsg, wParam, lParam);\n SetWindowLongPtr(m_hwnd, GWLP_USERDATA, 0);\n delete this;\n return lres;\n case WM_PAINT:\n OnPaint();\n return 0;\n case WM_PRINTCLIENT:\n OnPrintClient(reinterpret_cast<HDC>(wParam));\n return 0;\n }\n return DefWindowProc(m_hwnd, uMsg, wParam, lParam);\n}\nvoid Window::OnPaint()\n{\n PAINTSTRUCT ps;\n BeginPaint(m_hwnd, &ps);\n PaintContent(&ps);\n EndPaint(m_hwnd, &ps);\n}\nvoid Window::OnPrintClient(HDC hdc)\n{\n PAINTSTRUCT ps;\n ps.hdc = hdc;\n GetClientRect(m_hwnd, &ps.rcPaint);\n PaintContent(&ps);\n}\nclass RootWindow : public Window\n{\npublic:\n virtual LPCTSTR ClassName() { return TEXT(\"Scratch\"); }\n static RootWindow *Create();\nprotected:\n LRESULT HandleMessage(UINT uMsg, WPARAM wParam, LPARAM lParam);\n LRESULT OnCreate();\nprivate:\n HWND m_hwndChild;\n};\nLRESULT RootWindow::OnCreate()\n{\n return 0;\n}\nLRESULT RootWindow::HandleMessage(\n UINT uMsg, WPARAM wParam, LPARAM lParam)\n{\n switch (uMsg) {\n case WM_CREATE:\n return OnCreate();\n case WM_NCDESTROY:\n \/\/ Death of the root window ends the thread\n PostQuitMessage(0);\n break;\n case WM_SIZE:\n if (m_hwndChild) {\n SetWindowPos(m_hwndChild, NULL, 0, 0,\n GET_X_LPARAM(lParam), GET_Y_LPARAM(lParam),\n SWP_NOZORDER | SWP_NOACTIVATE);\n }\n return 0;\n case WM_SETFOCUS:\n if (m_hwndChild) {\n SetFocus(m_hwndChild);\n }\n return 0;\n }\n return __super::HandleMessage(uMsg, wParam, lParam);\n}\nRootWindow *RootWindow::Create()\n{\n RootWindow *self = new RootWindow();\n if (self && self->WinCreateWindow(0,\n TEXT(\"Scratch\"), WS_OVERLAPPEDWINDOW,\n CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT,\n NULL, NULL)) {\n return self;\n }\n delete self;\n return NULL;\n}\nint PASCAL\nWinMain(HINSTANCE hinst, HINSTANCE, LPSTR, int nShowCmd)\n{\n g_hinst = hinst;\n if (SUCCEEDED(CoInitialize(NULL))) {\n InitCommonControls();\n RootWindow *prw = RootWindow::Create();\n if (prw) {\n ShowWindow(prw->GetHWND(), nShowCmd);\n MSG msg;\n while (GetMessage(&msg, NULL, 0, 0)) {\n TranslateMessage(&msg);\n DispatchMessage(&msg);\n }\n }\n CoUninitialize();\n }\n return 0;\n}\n<\/pre>\n\nThe basic idea of this program is the same as our old\nscratch program, but now it has that fresh lemony C++ scent.\nInstead of keeping our state in globals, we declare a C++ class\nand hook it up to the window.\nFor simplicity,\nthe object’s lifetime is tied to the window itself.\n<\/p>\n
\nFirst, there is a bare-bones Window<\/code> class which we\nwill use as our base class for any future “class associated with a\nwindow” work.\nThe only derived class for now is the RootWindow<\/code>,\nthe top-level frame window that for now is the only window that the\nprogram uses.\nAs you may suspect, we may have other derived classes later\nas the need arises.\n<\/p>\n\nThe reason why the WinRegisterClass<\/code> method is\nvirtual (and doesn’t do anything interesting) is so that\na derived class can modify the WNDCLASS<\/code> that is\nused when the class is registered.\nI don’t have any immediate need for it, but it’ll be there if I need it.\n<\/p>\n