6.1 键盘基础
6.1.1 谁获得了焦点？
（1）活动窗口：桌面最上层窗口，其父窗口句柄为NULL，加亮标题栏或突出显示在任务栏。
（2）焦点窗口：活动窗口的子孙窗口，通常是一个闪烁的插入符或虚线框指示输入焦点
（3）捕获WM_SETFOCUS来确定其具有输入焦点，WM_KILLFOCUS说明正失去焦点
（4）当所有程序都最小化时，没有窗口具有输入焦点，Windows仍将发送键盘消息给活动窗口。这时所有击键都产生WM_SYSKEYDOWN和WM_SYSKEYUP消息。
6.1.2 队列和同步
（1）两步法处理键消息：先把消息存储在系统消息队列里，再发送到应用程序消息队列里。具休：①击键事件→将扫描码转为消息，放入系统消息队列（注意不立即放入应用程序消息队列）；②应用程序处理完前一个输入消息→Windows从系统队列取下一条消息放入应用程序消息队列。
（2）两步处理法的原因——同步
因为当应用程序1接收到一个特殊的、转换窗口焦点的击键动作时，后续的击键消息也应被转移到另一个程序（如应用程序2）的队列中去。如果键盘消息不经系统队列的缓冲，当用户输入太快，而应用程序1来不及没处理完这个特殊消息时，可能后续的击键消息又被发送到应用程序1的队列中来了，从而导致错误。因此，键盘消息要先放到系统队列中，起到同步的作用。
6.1.3 击键和字符
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键盘消息（8个消息） |
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两类消息 |
非系统消息（未按ALT键） |
系统消息（按下ALT键） |
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击键消息 |
WM_KEYDOWN WM_KEYUP |
WM_SYSKEYDOWN WM_SYSKEYUP |
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字符消息 |
WM_CHAR WM_DEADCHAR |
WM_SYSCHAR WM_SYSDEADCHAR |
6.2 击键消息
6.2.1 系统键击和非系统键击
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系统键击(按下ALT) |
非系统键击（未按ALT） |
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case WM_SYSKEYDOWN: case WM_SYSKEUP: case WM_SYSCHAR: ……//拦截系统消息并处理； DefWindowProc(…);//要传下去 return 0; |
case WM_KEYDOWN: case WM_KEUP: case WM_CHAR: //处理完后直接返回。 return 0; |
6.2.2 虚拟键代码——wParam信息
（1）键盘扫描码：键的真实键码，是按自然键盘硬件布局产生的，每个键都两个扫描码，即通码和断码（1个字节），满足：断码 = 通码+ 80H。即通码第7位为0，断码为1。
（2）虚拟键：与为做到与设备无关方式来处理键盘，定义了虚拟键，命名以VK_开头，一般都是扫描码的通码。如Q键为16、W为17、E为18、T为19等。
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10进制 |
16进制 |
标识符 |
常用？ |
IBM兼容键盘 |
备注 |
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1 |
01 |
VK_LBUTTON |
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鼠标左键 |
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2 |
02 |
VK_RBUTTON |
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鼠标右键 |
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3 |
03 |
VK_CANCEL |
√ |
Ctrl+Break |
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4 |
04 |
VK_MBUTTON |
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鼠标中键 |
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5 |
05 |
VK_XBUTTON1 |
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6 |
06 |
VK_XBUTTON2 |
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8 |
08 |
VK_BACK |
√ |
退格键 |
1、通常使用字符消息（而不是击键消息）来处理这些键 2、应用程序不必去监视Shift、Ctrl或Alt键的状态。 |
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9 |
09 |
VK_TAB |
√ |
Tab键 |
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12 |
0C |
VK_CLEAR |
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数字锁定键关闭时的数字键 |
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13 |
0D |
VK_RETURN |
√ |
回车键（任意一个） |
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16 |
10 |
VK_SHIFT |
√ |
Shift键（任意一个） |
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17 |
11 |
VK_CONTROL |
√ |
Ctrl键（任意一个） |
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18 |
12 |
VK_MENU |
√ |
Alt键（任意一个） |
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19 |
13 |
VK_PAUSE |
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Pause键 |
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20 |
14 |
VK_CAPITAL |
√ |
大写锁定键 |
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27 |
1B |
VK_ESCAPE |
√ |
Esc键 |
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32 |
20 |
VK_SPACE |
√ |
空格键 |
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33 |
21 |
VK_PRIOR |
√ |
PageUp键 |
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34 |
22 |
VK_NEXT |
√ |
PageDown键 |
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35 |
23 |
VK_END |
√ |
End键 |
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36 |
24 |
VK_HOME |
√ |
Home键 |
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37 |
25 |
VK_LEFT |
√ |
左箭头 |
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38 |
26 |
VK_UP |
√ |
上箭头 |
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39 |
27 |
VK_RIGHT |
√ |
右箭头 |
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40 |
28 |
VK_DOWN |
√ |
下箭头 |
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41 |
29 |
VK_SELECT |
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假想的键盘码 |
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42 |
2A |
VK_PRINT |
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43 |
2B |
VK_EXCUTE |
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44 |
2C |
VK_SNAPSHOT |
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Print Screen键 |
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45 |
2D |
VK_INSERT |
√ |
Insert键 |
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46 |
2E |
VK_DELETE |
√ |
Del键 |
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47 |
2F |
VK_HELP |
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48-57 |
30-39 |
无 |
√ |
主键盘上的0-9 |
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65-90 |
41-5A |
无 |
√ |
A到Z |
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91 |
5B |
VK_LWIN |
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左Windows键 |
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92 |
5C |
VK_RWIN |
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右Windows键 |
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93 |
5D |
VK_APPS |
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Application键 |
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96-105 |
60-69 |
VK_NUMPAD0-VK_NUMPAD9 |
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数字锁定键打开时，小键盘数字键的0-9 |
数字小键盘 |
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106 |
6A |
VK_MULTIPLY |
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数字区的* |
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107 |
6B |
VK_ADD |
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数字区的+ |
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108 |
6C |
VK_SEPARATOR |
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109 |
6D |
VK_SUBTRACT |
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数字区的- |
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110 |
6E |
VK_DECIMAL |
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数字区的. |
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111 |
6F |
VK_DIVIDE |
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数字区的/ |
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112-121 |
70-79 |
VK_F1到VK_F10 |
√ |
功能键F1到F10 |
一般仅使用前10个 |
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122-135 |
7A-87 |
VK_F11到VK_F24 |
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功能键F11到F24 |
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144 |
90 |
VK_NUMLOCK |
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数字锁定键 |
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145 |
91 |
VK_SCROLL |
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Scroll Lock键 |
6.2.3 lParam信息
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消息字段 |
说明 |
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1、重复计数 |
①大多数情况下为1，但如果按下一个键不放，将合并WM_KEYDOWN或WM_SYSKEYDOWN成一条单独的消息，并增加重复计数字段。 ②重复计数＞1，可能通过重复计数利用或废弃连续击键的消息。 |
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2、OEM扫描码 |
键盘硬件产生的代码，是从BIOS中获得的。 |
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3、扩展键标记 |
来自于IBM加强型的附加键时标记1。Windows通常忽略扩展键标记。 |
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4、内容代码 |
①按下ALT时（即WM_SYSKEY…）为1，不按时（WM_KEY…）为0。 ②两种特殊情况： A、未按Alt（置0），但当所有活动窗口最小化，不具有输入焦点时，所有的击键将转为WM_SYSKEYUP或WM_SYSKEYDOWN。Windows发送这两种消息表明要自己处理，而不让窗口处理。 B、非英语键盘上，部分字符是由Shift、Ctrl或Alt同另一个键组合产生的。这时被置1，但该消息并不是系统击键消息。 |
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5、键的先前状态 |
①如果原先的状态。即消息发送以前，按键原来的状态：按下的为1，按键释放的为0。 ②WM_KEYUP或WM_SYSKEYUP先前状态总是1。 ③WM_KEYDOWN或WM_SYSKEYDOWN可能为0或1。表示重复击键。 |
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6、转换状态 |
①正按下为0，正释放为1 ②WM_KEYDOWN或WM_SYSKEYDOWN总为0. ③WM_KEYUP或WM_SYSKEYUP总为1. |
6.2.4 转义状态
（1）3个获得键状态的函数对比
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GetKeyState |
①从消息队列中取得键盘状态，只能在键盘消息处理程序中使用。 ②返回值：高位为1（表示负数），表示键被按下。 |
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GetAsyncKeyState |
①作用：判断某键是否down或up。 ②返回值short型，最高位表示是否按下，up为0，down为1。最低位表示键在此函数调用之前是否被按下过。 |
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GetKeyboardState |
①作用：获得所有的256个键（键盘按键、鼠标按键等等）的状态。 ②参数是指向一个256bit的数组，存放所有键的状态 ③当从windows消息队列中移除键盘消息时，才返回。 |
（2）应用举例——获取按键状态的几种方法
① if ((nChar==0x041)&& (GetKeyState(VK_CONTROL)&0x8000)) //ctrl+A
②#defineKEYDOWN(vk_code) ((GetAsyncKeyState(vk_code) & 0x8000) ? 1 : 0)
③if(GetAsyncKeyState(VK_LSHIFT))
6.2.5 使用击键消息——不产生字符的键盘消息放在WM_KEYDOWN或WM_KEYUP中处理
如：处理光标移动键、Insert、Delete键的WM_KEYDOWN消息，在这些消息中可以通过GetKeyState检查Shift和Ctrl的状态。
6.2.6 为SYSMETS加上键盘处理功能
//SysMets.h
/*----------------------------------------------- SYSMETS.H -- System metrics display structure -----------------------------------------------*/ #pragma once #include <windows.h> #define NUMLINES ((int) (sizeof sysmetrics / sizeof sysmetrics [0])) struct { int iIndex; TCHAR * szLabel; 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"), SM_CXMINSPACING, TEXT("SM_CXMINSPACING"), TEXT("Minimized window spacing width"), SM_CYMINSPACING, TEXT("SM_CYMINSPACING"), TEXT("Minimized window spacing height"), SM_CXSMICON, TEXT("SM_CXSMICON"), TEXT("Small icon width"), SM_CYSMICON, TEXT("SM_CYSMICON"), TEXT("Small icon height"), SM_CYSMCAPTION, TEXT("SM_CYSMCAPTION"), TEXT("Small caption height"), SM_CXSMSIZE, TEXT("SM_CXSMSIZE"), TEXT("Small caption button width"), SM_CYSMSIZE, TEXT("SM_CYSMSIZE"), TEXT("Small caption button height"), SM_CXMENUSIZE, TEXT("SM_CXMENUSIZE"), TEXT("Menu bar button width"), SM_CYMENUSIZE, TEXT("SM_CYMENUSIZE"), TEXT("Menu bar button height"), SM_ARRANGE, TEXT("SM_ARRANGE"), TEXT("How minimized windows arranged"), SM_CXMINIMIZED, TEXT("SM_CXMINIMIZED"), TEXT("Minimized window width"), SM_CYMINIMIZED, TEXT("SM_CYMINIMIZED"), TEXT("Minimized window height"), SM_CXMAXTRACK, TEXT("SM_CXMAXTRACK"), TEXT("Maximum dragable width"), SM_CYMAXTRACK, TEXT("SM_CYMAXTRACK"), TEXT("Maximum dragable height"), SM_CXMAXIMIZED, TEXT("SM_CXMAXIMIZED"), TEXT("Width of maximized window"), SM_CYMAXIMIZED, TEXT("SM_CYMAXIMIZED"), TEXT("Height of maximized window"), SM_NETWORK, TEXT("SM_NETWORK"), TEXT("Network present flag"), SM_CLEANBOOT, TEXT("SM_CLEANBOOT"), TEXT("How system was booted"), SM_CXDRAG, TEXT("SM_CXDRAG"), TEXT("Avoid drag x tolerance"), SM_CYDRAG, TEXT("SM_CYDRAG"), TEXT("Avoid drag y tolerance"), SM_SHOWSOUNDS, TEXT("SM_SHOWSOUNDS"), TEXT("Present sounds visually"), SM_CXMENUCHECK, TEXT("SM_CXMENUCHECK"), TEXT("Menu check-mark width"), SM_CYMENUCHECK, TEXT("SM_CYMENUCHECK"), TEXT("Menu check-mark height"), SM_SLOWMACHINE, TEXT("SM_SLOWMACHINE"), TEXT("Slow processor flag"), SM_MIDEASTENABLED, TEXT("SM_MIDEASTENABLED"), TEXT("Hebrew and Arabic enabled flag"), SM_MOUSEWHEELPRESENT, TEXT("SM_MOUSEWHEELPRESENT"), TEXT("Mouse wheel present flag"), SM_XVIRTUALSCREEN, TEXT("SM_XVIRTUALSCREEN"), TEXT("Virtual screen x origin"), SM_YVIRTUALSCREEN, TEXT("SM_YVIRTUALSCREEN"), TEXT("Virtual screen y origin"), SM_CXVIRTUALSCREEN, TEXT("SM_CXVIRTUALSCREEN"), TEXT("Virtual screen width"), SM_CYVIRTUALSCREEN, TEXT("SM_CYVIRTUALSCREEN"), TEXT("Virtual screen height"), SM_CMONITORS, TEXT("SM_CMONITORS"), TEXT("Number of monitors"), SM_SAMEDISPLAYFORMAT, TEXT("SM_SAMEDISPLAYFORMAT"), TEXT("Same color format flag") };
//SysMets3.c
/*---------------------------------------------------- SYSMETS3.C -- System Metrics Display Program No. 3 (c) Charles Petzold, 1998 ----------------------------------------------------*/ #define WINVER 0x0500 #include <windows.h> #include "sysmets.h" LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM); int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow) { static TCHAR szAppName[] = TEXT("SysMets3"); HWND hwnd; MSG msg; WNDCLASS wndclass; wndclass.style = CS_HREDRAW | CS_VREDRAW; wndclass.lpfnWndProc = WndProc; wndclass.cbClsExtra = 0; wndclass.cbWndExtra = 0; wndclass.hInstance = hInstance; wndclass.hIcon = LoadIcon(NULL, IDI_APPLICATION); wndclass.hCursor = LoadCursor(NULL, IDC_ARROW); wndclass.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH); wndclass.lpszMenuName = NULL; wndclass.lpszClassName = szAppName; if (!RegisterClass(&wndclass)) { MessageBox(NULL, TEXT("Program requires Windows NT!"), szAppName, MB_ICONERROR); return 0; } hwnd = CreateWindow(szAppName, TEXT("Get System Metrics No. 3"), WS_OVERLAPPEDWINDOW | WS_VSCROLL | WS_HSCROLL, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, NULL, NULL, hInstance, NULL); 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, cxClient, cyClient, iMaxWidth; HDC hdc; int i, x, y, iVertPos, iHorzPos, iPaintBeg, iPaintEnd; PAINTSTRUCT ps; SCROLLINFO si; TCHAR szBuffer[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); // Save the width of the three columns iMaxWidth = 40 * cxChar + 22 * cxCaps; return 0; case WM_KEYDOWN: //处理键盘消息 switch (wParam) { //垂直滚动条 case VK_HOME: SendMessage(hwnd, WM_VSCROLL, SB_TOP, 0);//模拟发送滚动条消息 break; case VK_END: SendMessage(hwnd, WM_VSCROLL, SB_BOTTOM, 0); break; case VK_PRIOR: SendMessage(hwnd, WM_VSCROLL, SB_PAGEUP, 0); break; case VK_NEXT: SendMessage(hwnd, WM_VSCROLL, SB_PAGEDOWN, 0); break; case VK_UP: SendMessage(hwnd, WM_VSCROLL, SB_LINEUP, 0); break; case VK_DOWN: SendMessage(hwnd, WM_VSCROLL, SB_LINEDOWN, 0); break; case VK_LEFT: SendMessage(hwnd, WM_HSCROLL, SB_LINELEFT, 0); break; case VK_RIGHT: SendMessage(hwnd, WM_HSCROLL, SB_LINERIGHT, 0); break; } return 0; case WM_SIZE: cxClient = LOWORD(lParam); cyClient = HIWORD(lParam); // Set vertical scroll bar range and page size si.cbSize = sizeof (si); si.fMask = SIF_RANGE | SIF_PAGE; si.nMin = 0; si.nMax = NUMLINES - 1; si.nPage = cyClient / cyChar; SetScrollInfo(hwnd, SB_VERT, &si, TRUE); // Set horizontal scroll bar range and page size si.cbSize = sizeof (si); si.fMask = SIF_RANGE | SIF_PAGE; si.nMin = 0; si.nMax = 2 + iMaxWidth / cxChar; si.nPage = cxClient / cxChar; SetScrollInfo(hwnd, SB_HORZ, &si, TRUE); return 0; case WM_VSCROLL: // Get all the vertial scroll bar information si.cbSize = sizeof (si); si.fMask = SIF_ALL; GetScrollInfo(hwnd, SB_VERT, &si); // Save the position for comparison later on iVertPos = si.nPos; switch (LOWORD(wParam)) { case SB_TOP: si.nPos = si.nMin; break; case SB_BOTTOM: si.nPos = si.nMax; break; case SB_LINEUP: si.nPos -= 1; break; case SB_LINEDOWN: si.nPos += 1; break; case SB_PAGEUP: si.nPos -= si.nPage; break; case SB_PAGEDOWN: si.nPos += si.nPage; break; case SB_THUMBTRACK: si.nPos = si.nTrackPos; break; default: break; } // Set the position and then retrieve it. Due to adjustments // by Windows it may not be the same as the value set. si.fMask = SIF_POS; SetScrollInfo(hwnd, SB_VERT, &si, TRUE); GetScrollInfo(hwnd, SB_VERT, &si); // If the position has changed, scroll the window and update it if (si.nPos != iVertPos) { ScrollWindow(hwnd, 0, cyChar * (iVertPos - si.nPos), NULL, NULL); UpdateWindow(hwnd); } return 0; case WM_HSCROLL: // Get all the vertial scroll bar information si.cbSize = sizeof (si); si.fMask = SIF_ALL; // Save the position for comparison later on GetScrollInfo(hwnd, SB_HORZ, &si); iHorzPos = si.nPos; switch (LOWORD(wParam)) { case SB_LINELEFT: si.nPos -= 1; break; case SB_LINERIGHT: si.nPos += 1; break; case SB_PAGELEFT: si.nPos -= si.nPage; break; case SB_PAGERIGHT: si.nPos += si.nPage; break; case SB_THUMBPOSITION: si.nPos = si.nTrackPos; break; default: break; } // Set the position and then retrieve it. Due to adjustments // by Windows it may not be the same as the value set. si.fMask = SIF_POS; SetScrollInfo(hwnd, SB_HORZ, &si, TRUE); GetScrollInfo(hwnd, SB_HORZ, &si); // If the position has changed, scroll the window if (si.nPos != iHorzPos) { ScrollWindow(hwnd, cxChar * (iHorzPos - si.nPos), 0, NULL, NULL); } return 0; case WM_PAINT: hdc = BeginPaint(hwnd, &ps); // Get vertical scroll bar position si.cbSize = sizeof (si); si.fMask = SIF_POS; GetScrollInfo(hwnd, SB_VERT, &si); iVertPos = si.nPos; // Get horizontal scroll bar position GetScrollInfo(hwnd, SB_HORZ, &si); iHorzPos = si.nPos; // Find painting limits iPaintBeg = max(0, iVertPos + ps.rcPaint.top / cyChar); iPaintEnd = min(NUMLINES - 1, iVertPos + ps.rcPaint.bottom / cyChar); for (i = iPaintBeg; i <= iPaintEnd; i++) { x = cxChar * (1 - iHorzPos); y = cyChar * (i - iVertPos); TextOut(hdc, x, y, sysmetrics[i].szLabel, lstrlen(sysmetrics[i].szLabel)); TextOut(hdc, x + 22 * cxCaps, y, sysmetrics[i].szDesc, lstrlen(sysmetrics[i].szDesc)); SetTextAlign(hdc, TA_RIGHT | TA_TOP); TextOut(hdc, x + 22 * cxCaps + 40 * cxChar, y, szBuffer, wsprintf(szBuffer, TEXT("%5d"), GetSystemMetrics(sysmetrics[i].iIndex))); SetTextAlign(hdc, TA_LEFT | TA_TOP); } EndPaint(hwnd, &ps); return 0; case WM_DESTROY: PostQuitMessage(0); return 0; } return DefWindowProc(hwnd, message, wParam, lParam); }