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1 绘制和重绘

1.1 WM_PAINT消息

1.2 有效矩形和无效矩形

2 GDI简介（图形设备接口（GDI ：Graphics Device Interface）

2.1 设备环境

2.2 方式1：BeginPaint

注意：在调用BeginPaint后，整个客户区会变成有效的。

2.3 绘制信息结构

typedef struct tagPAINTSTRUCT {    HDC         hdc;     //设备环境句柄    BOOL        fErase;  //大多数情况，被被设置为FALSE    RECT        rcPaint;   //定义了无效矩形的边界    BOOL        fRestore;    BOOL        fIncUpdate;    BYTE        rgbReserved[32];} PAINTSTRUCT, *PPAINTSTRUCT, *NPPAINTSTRUCT, *LPPAINTSTRUCT;

2.4 获取设备环境句柄：方法二 GetDC

2.5 TEXTOUT函数详解

WINGDIAPI BOOL  WINAPI TextOutA( _In_ HDC hdc, _In_ int x, _In_ int y, _In_reads_(c) LPCSTR lpString, _In_ int c);WINGDIAPI BOOL  WINAPI TextOutW( _In_ HDC hdc, _In_ int x, _In_ int y, _In_reads_(c) LPCWSTR lpString, _In_ int c);#ifdef UNICODE#define DrawText  DrawTextW#else#define DrawText  DrawTextA#endif // !UNICODE

2.6 系统字体

2.7 字符大小

2.8 文本尺寸的度量

2.9 文本的格式化

如果要在视窗中显示字体，就必须首先取得字元的高度和宽度，可以在开始定义两个变量来保存平均字元的宽度和总的字元高度，如下：

cxChar = tm.tmAveCharWidth ;   cyChar = tm.tmHeight + tm.tmExternalLeading ;

可以看到在计算cyChar时包括了tmExternalLeading 栏位来确保可读性。

2.10 综合使用

/*------------------------------------- SYSMETS.H -- System metrics display structure---------------------------------------*/#include 
   
    #include 
    
     #define NUMLINES ((int) (sizeof sysmetrics / sizeof sysmetrics [0])) struct {	int index;	TCHAR * szLable;	TCHAR * szDesc;}sysmetrics[] = {	SM_CXSCREEN,      TEXT("SM_CXSCREEN"), TEXT("Screen width in pixels"),	SM_CYSCREEN,	  TEXT("SM_CYSCREEN"),TEXT("Screen height in pixels"),	SM_CXVSCROLL,	  TEXT("SM_CXVSCROLL"), TEXT("Vertical scroll width"), 	SM_CYHSCROLL,	  TEXT("SM_CYHSCROLL"), TEXT("Horizontal scroll height"),	SM_CYCAPTION,	 TEXT("SM_CYCAPTION"),  TEXT("Caption bar height"), 	SM_CXBORDER,	 TEXT("SM_CXBORDER"),    TEXT("Window border width"), 	SM_CYBORDER,	 TEXT("SM_CYBORDER"),     TEXT("Window border height"),  	SM_CXFIXEDFRAME,	TEXT("SM_CXFIXEDFRAME"),   TEXT("Dialog window frame width"),	SM_CYFIXEDFRAME,	TEXT("SM_CYFIXEDFRAME"),   TEXT("Dialog window frame height"),	SM_CYVTHUMB,	TEXT("SM_CYVTHUMB"),    TEXT("Vertical scroll thumb height"),  	SM_CXHTHUMB,    TEXT("SM_CXHTHUMB"),  TEXT("Horizontal scroll thumb width"), 	SM_CXICON,      TEXT("SM_CXICON"),   TEXT("Icon width"),  	SM_CYICON,	  TEXT("SM_CYICON"),          TEXT("Icon height"), 	SM_CXCURSOR,	 TEXT("SM_CXCURSOR"),      TEXT("Cursor width"),	SM_CYCURSOR,    TEXT("SM_CYCURSOR"),      TEXT("Cursor height"),	SM_CYMENU,      TEXT("SM_CYMENU"),        TEXT("Menu bar height"), 	SM_CXFULLSCREEN, TEXT("SM_CXFULLSCREEN"),  TEXT("Full screen client area width"), 	SM_CYFULLSCREEN, TEXT("SM_CYFULLSCREEN"),  TEXT("Full screen client area height"), 	SM_CYKANJIWINDOW, TEXT("SM_CYKANJIWINDOW"),  TEXT("Kanji window height"),	SM_MOUSEPRESENT, TEXT("SM_MOUSEPRESENT"),     TEXT("Mouse present flag"),  	SM_CYVSCROLL,  TEXT("SM_CYVSCROLL"),         TEXT("Vertical scroll arrow height"),	SM_CXHSCROLL,  TEXT("SM_CXHSCROLL"),      TEXT("Horizontal scroll arrow width"),	SM_DEBUG,       TEXT("SM_DEBUG"),     TEXT("Debug version flag"),	SM_SWAPBUTTON,  TEXT("SM_SWAPBUTTON"),  TEXT("Mouse buttons swapped flag"), 	SM_CXMIN,      TEXT("SM_CXMIN"),         TEXT("Minimum window width"), 	SM_CYMIN,      TEXT("SM_CYMIN"),        TEXT("Minimum window height"), 	SM_CXSIZE,      TEXT("SM_CXSIZE"),      TEXT("Min/Max/Close button width"), 	SM_CYSIZE,      TEXT("SM_CYSIZE"),       TEXT("Min/Max/Close button height"),	SM_CXSIZEFRAME,  TEXT("SM_CXSIZEFRAME"),    TEXT("Window sizing frame width"),  	SM_CYSIZEFRAME,  TEXT("SM_CYSIZEFRAME"),    TEXT("Window sizing frame height"), 	SM_CXMINTRACK,  TEXT("SM_CXMINTRACK"),      TEXT("Minimum window tracking width"),	SM_CYMINTRACK,  TEXT("SM_CYMINTRACK"),       TEXT("Minimum window tracking height"),	SM_CXDOUBLECLK,  TEXT("SM_CXDOUBLECLK"),     TEXT("Double click x tolerance"),  	SM_CYDOUBLECLK,  TEXT("SM_CYDOUBLECLK"),      TEXT("Double click y tolerance"), 	SM_CXICONSPACING,TEXT("SM_CXICONSPACING"),    TEXT("Horizontal icon spacing"), 	SM_CYICONSPACING,TEXT("SM_CYICONSPACING"),     TEXT("Vertical icon spacing"),	SM_MENUDROPALIGNMENT, TEXT("SM_MENUDROPALIGNMENT"),   TEXT("Left or right menu drop"), 	SM_PENWINDOWS,         TEXT("SM_PENWINDOWS"),         TEXT("Pen extensions installed"), 	SM_DBCSENABLED,         TEXT("SM_DBCSENABLED"),       TEXT("Double-Byte Char Set enabled"), 	SM_CMOUSEBUTTONS,     TEXT("SM_CMOUSEBUTTONS"),    TEXT("Number of mouse buttons"), 	SM_SECURE,    TEXT("SM_SECURE"),            TEXT("Security present flag"),	SM_CXEDGE, TEXT("SM_CXEDGE"),               TEXT("3-D border width"), 	SM_CYEDGE, TEXT("SM_CYEDGE"),          TEXT("3-D border height"),};
    
   

/*------------------------------------- 将SYSMETS.H中的结构体显示到视窗上面 ---------------------------------------*/#include
   
    #include "SYSTEMS.h"LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR sCmdLine, int iCmdShow) {	static TCHAR szAppName[] = TEXT("SysMets1");	HWND hwnd;	MSG msg;	WNDCLASSEX wndclass;	wndclass.cbSize = sizeof(wndclass); //结构的大小（必须定义结构大小）	wndclass.style = CS_HREDRAW | CS_VREDRAW; //重绘	wndclass.lpfnWndProc = WndProc; //窗口函数指针	wndclass.cbClsExtra = 0; //没有额外的类内存	wndclass.cbWndExtra = 0; //没有额外的窗体内存	wndclass.hInstance = hInstance;  //实例句柄	wndclass.hIcon = ::LoadIcon(NULL, IDI_APPLICATION);//使用预定义的图标	wndclass.hCursor = ::LoadCursor(NULL, IDC_ARROW); //使用预定义光标	wndclass.hbrBackground = (HBRUSH)::GetStockObject(WHITE_BRUSH);//使用白色背景画刷		wndclass.lpszMenuName = NULL;  //不指定菜单	wndclass.lpszClassName = szAppName;  //窗口类的名称	wndclass.hIconSm = NULL; //没有类的小图标	if (!RegisterClassEx(&wndclass)) {		MessageBox(NULL, TEXT("Can't funcitom"), szAppName, MB_ICONERROR);		return 0;	}		hwnd = CreateWindowEx(		0,  //dwExStyle, 扩展样式 		szAppName, //lpClassName,类名		"WindowsName",  //lpWindowName窗口名称		WS_OVERLAPPEDWINDOW, //dwStyle, 窗口风格		CW_USEDEFAULT,  //X,初始X坐标		CW_USEDEFAULT,  //Y，初始Y坐标		CW_USEDEFAULT,  //nWight， 宽度		CW_USEDEFAULT,  //nHight， 高度		NULL,  //hWndParent， 父窗口句柄		NULL,  //hMenu， 菜单句柄		hInstance,  //hInstance， 程序实例句柄		NULL   //ipParam，用户数据	);	::ShowWindow(hwnd, iCmdShow);	::UpdateWindow(hwnd);	while (::GetMessage(&msg, NULL, 0, 0)) {		::TranslateMessage(&msg);		::DispatchMessage(&msg);		}	return msg.wParam;}LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam) {	static int cxChar, cxCaps, cyChar;	HDC hdc;	int i;	PAINTSTRUCT ps;	TCHAR szBuff[10];	TEXTMETRIC tm;	switch (message)	{	case WM_CREATE:		hdc = GetDC(hwnd);		GetTextMetrics(hdc, &tm);		cxChar = tm.tmAveCharWidth;		cxCaps = (tm.tmPitchAndFamily & 1 ? 3 : 2)* cxChar / 2;		cyChar = tm.tmHeight + tm.tmExternalLeading;		ReleaseDC(hwnd, hdc);		return 0;	case WM_PAINT:		hdc = BeginPaint(hwnd, &ps);		for (int i = 0; i < NUMLINES; i++) {			TextOut(hdc, 0, cyChar * i, sysmetrics[i].szLable,				lstrlen(sysmetrics[i].szLable));			TextOut(hdc, 22 * cxCaps, cyChar * i, sysmetrics[i].szDesc,				lstrlen(sysmetrics[i].szDesc));			SetTextAlign(hdc, TA_RIGHT | TA_TOP);			TextOut(hdc, 22 * cxCaps + 40 * cxChar, cyChar * i, szBuff, wsprintf(szBuff, TEXT("%5d"),				GetSystemMetrics(sysmetrics[i].index)));			SetTextAlign(hdc, TA_LEFT | TA_TOP);		}		EndPaint(hwnd, &ps);		return 0;	case WM_DESTROY:		PostQuitMessage(0);		return 0;	}	return DefWindowProc(hwnd, message, wParam, lParam);}