createwindow
by WJB date 2108/08/29
最近学了通过windows API 创建窗体 用到了createwindow函数。
CreateWindow(
LPCTSTR lpClassName, //这个名字一定要与 声明的WNDCLASS 对象中lpszClassName的值一致
LPCTSTR lpWindowName, //窗体左上角显示的窗体名称
Dword dwStyle,
int x,
int y,
int nWidth，
int nHeight，
HWND hWndparent,
HMENU hMenu，
handle hlnstance，
LPVOID lpParam
）
重点记录一下最后一个参数 LPVOID lpParam
指向一个值的指针，该值传递给窗口WM_CREATE消息。该值通过在IParam参数中的CREATEstruct结构传递。如果应用程序调用CreateWindow创建一个MDI客户窗口，则lpParam必须指向一个CLIENTCREATESTRUCT结构。
CREATESTRUCT 结构如下所示：
typedef struct tagCREATESTRUCTW {
LPVOID lpCreateparams;
Hinstance hInstance;
HMENU hMenu;
HWND hwndParent;
int cy;
int cx;
int y;
int x;
LONG style;
LPCWSTR lpszName;
LPCWSTR lpszClass;
dword dwExStyle;
} CREATESTRUCT;
LPVOID lpParam 这个参数再HWDCLASS 中lpfnWndProc回调函数中传递
例如 回调函数如下
LRESULT CALLBACK MainWndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
static D3DAPP* app = 0;
switch (msg)
{
case WM_CREATE:
{
CREATESTRUCT* cs = (CREATESTRUCT*)lParam;
return 0;
}
}
// Don't start processing messages until after WM_CREATE.
if (app)
return app->msgProc(msg, wParam, lParam);
else
return DefWindowProc(hwnd, msg, wParam, lParam);
}
传递给窗口WM_CREATE时，即可取到该值；
//D3Dapp.h
#include <windows.h>
class D3DApp
{
public:
D3DApp(HINSTANCE hInstance);
virtual ~D3DApp();
HINSTANCE getAppInst();
HWND getMainWnd(); //获取主窗体
int run();
virtual void initApp();
virtual LRESULT msgProc(UINT msg, WPARAM wParam, LPARAM lParam);
void initMainWindow();
protected:
///////////////////////////////////////////////////////////////////////////
//windows 变量
HINSTANCE mhAppInst;
HWND mhMainWnd;
int mclientwidth;
int mclientheight;
};
//D3Dapp.cpp
#include "D3DApp.h"
LRESULT CALLBACK MainWndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
static D3DApp* app = 0;
switch (msg)
{
case WM_CREATE:
{
// Get the 'this' pointer we passed to CreateWindow via the lpParam parameter.
CREATESTRUCT* cs = (CREATESTRUCT*)lParam;
app = (D3DApp*)cs->lpCreateParams;
return 0;
}
}
// Don't start processing messages until after WM_CREATE.
if (app)
return app->msgProc(msg, wParam, lParam);
else
return DefWindowProc(hwnd, msg, wParam, lParam);
}
D3DApp::D3DApp(HINSTANCE hInstance)
{
mClientWidth = 800;
mClientHeight = 600;
mhAppInst = hInstance;
}
D3DApp::~D3DApp()
{
}
HINSTANCE D3DApp::getAppInst()
{
return mhAppInst;
}
HWND D3DApp::getMainWnd()
{
return mhMainWnd;
}
int D3DApp::run()
{
MSG msg = { 0 };
while (true)
{
if (PeekMessage(&msg, NULL, NULL, NULL, PM_REMOVE))
{
if (msg.message == WM_QUIT) //如果关闭消息就跳出
{
break;
}
TranslateMessage(&msg);
DispatchMessage(&msg); //派发消息
}
}
return 0;
}
void D3DApp::initApp()
{
initMainWindow(); //创建窗体
initDirect3D();
}
LRESULT D3DApp::msgProc(UINT msg, WPARAM wParam, LPARAM lParam)
{
return DefWindowProc(mhMainWnd, msg, wParam, lParam);;
}
void D3DApp::initMainWindow()
{
WNDCLASS wc2;
wc2.cbClsExtra = 0;
wc2.cbWndExtra = 0;
wc2.hbrBackground = NULL;
wc2.hCursor = LoadCursor(NULL, IDC_ARROW);
wc2.hIcon = LoadIcon(NULL, IDI_APPLICATION);
wc2.hInstance = mhAppInst;
wc2.lpfnWndProc = (WNDPROC)MainWndProc;
wc2.lpszClassName = L"D3DWindow";
wc2.lpszMenuName = NULL;
wc2.style = CS_HREDRAW | CS_VREDRAW; //样式
if (!RegisterClass(&wc2)) //窗口注册
{
MessageBox(NULL, L"notice", L"ERROR", MB_OK);
}
mhMainWnd = CreateWindowEx(NULL,
L"D3DWindow",
L"D3DWnd",
WS_overlapPEDWINDOW,
CW_USEDEFAULT,
CW_USEDEFAULT,
mClientWidth,
mClientHeight,
0, 0,
mhAppInst,
this);
if (mhMainWnd == 0)
{
MessageBox(0, L"CreateWindow failed", 0, 0);
return;
}
ShowWindow(mhMainWnd, SW_SHOW);
UpdateWindow(mhMainWnd);
}
//main.cpp
#include "D3DApp.h"
INT WINAPI WinMain(HINSTANCE hinstance, HINSTANCE hPreInstance, LPSTR IpCmdLine, int nShowCmd)
{
D3DApp app(hinstance);
app.initApp();
return app.run();
}
相关阅读
Before returning, CreateWindow sends a WM_CREATE message to the window procedure. For overlapped, pop-up, and child wind