7.5 捕获鼠标
（1）捕获鼠标：SetCapture（hwnd）——Windows将所有消息都发给hwnd窗口，鼠标消息总是以客户区消息的形式出现。即使鼠标位于非客户区也一样。lParam为客户区坐标。
（2）释放捕获：ReleaseCapture（）
（3）一般WM_LBUTTONDOWN时开始捕获，WM_LBUTTONUP时停止捕获。
【BlokOut程序】
/*------------------------------------------------------------ BLOKOUT1.C -- Mouse Button Demo Program (c) Charles Petzold, 1998 ------------------------------------------------------------*/ #include <windows.h> LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM); int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow) { static TCHAR szAppName[] = TEXT("BlokOut1"); 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("This program requires Windows NT!"), szAppName, MB_ICONERROR); return 0; } hwnd = CreateWindow(szAppName, // window class name TEXT("Mouse Button Demo"), // window caption WS_OVERLAPPEDWINDOW, // window style CW_USEDEFAULT, // initial x position CW_USEDEFAULT, // initial y position CW_USEDEFAULT, // initial x size CW_USEDEFAULT, // initial y size NULL, // parent window handle NULL, // window menu handle hInstance, // program instance handle NULL); // creation parameters ShowWindow(hwnd, iCmdShow); UpdateWindow(hwnd); while (GetMessage(&msg, NULL, 0, 0)) { TranslateMessage(&msg); DispatchMessage(&msg); } return msg.wParam; } void DrawBoxOutLine(HWND hwnd, POINT ptBeg, POINT ptEnd) { HDC hdc = GetDC(hwnd); SetROP2(hdc, R2_NOT); //屏幕色取反。可删除旧的边框，对于新的边框，用黑色去画。 SelectObject(hdc, GetStockObject(NULL_BRUSH)); Rectangle(hdc, ptBeg.x, ptBeg.y, ptEnd.x, ptEnd.y); ReleaseDC(hwnd, hdc); } LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam) { HDC hdc; PAINTSTRUCT ps; static POINT ptBeg, ptEnd, ptBoxBeg, ptBoxEnd; static BOOL fBlocking, fValidBox; switch (message) { case WM_LBUTTONDOWN: ptBeg.x = ptEnd.x = LOWORD(lParam); ptBeg.y = ptEnd.y = HIWORD(lParam); DrawBoxOutLine(hwnd, ptBeg, ptEnd); SetCursor(LoadCursor(NULL, IDC_CROSS)); fBlocking = TRUE; SetCapture(hwnd); //捕获鼠标 return 0; case WM_MOUSEMOVE: if (fBlocking) { SetCursor(LoadCursor(NULL, IDC_CROSS)); DrawBoxOutLine(hwnd, ptBeg, ptEnd); //删除旧边框 ptEnd.x = LOWORD(lParam); ptEnd.y = HIWORD(lParam); DrawBoxOutLine(hwnd, ptBeg, ptEnd); //画新边框 } return 0; case WM_CHAR: if (wParam == '\x1B' && fBlocking) //得加fBlocking，否则将不断切换显示与隐藏边框 { DrawBoxOutLine(hwnd, ptBeg, ptEnd); SetCursor(LoadCursor(NULL, IDC_ARROW)); fBlocking = FALSE; ReleaseCapture(); //释放鼠标 } return 0; case WM_LBUTTONUP: if (fBlocking) { DrawBoxOutLine(hwnd, ptBeg, ptEnd); //删除边框线 ptBoxBeg = ptBeg; ptBoxEnd.x = LOWORD(lParam); ptBoxEnd.y = HIWORD(lParam); SetCursor(LoadCursor(NULL, IDC_ARROW)); fValidBox = TRUE; fBlocking = FALSE; ReleaseCapture();//释放鼠标 InvalidateRect(hwnd, NULL, TRUE); } return 0; case WM_PAINT: hdc = BeginPaint(hwnd, &ps); if (fValidBox) //如果没有此句判断，会出现程序一运行就画矩形的错误。 { SelectObject(hdc, GetStockObject(BLACK_BRUSH)); Rectangle(hdc, ptBoxBeg.x, ptBoxBeg.y, ptBoxEnd.x, ptBoxEnd.y); } //当鼠标在客户区外释放，若此时再去调整窗口大小，旧边框仍保留着，得删除 if (fBlocking) { SetROP2(hdc, R2_NOT); //屏幕色取反。可删除旧的边框，对于新的边框，用黑色去画。 SelectObject(hdc, GetStockObject(NULL_BRUSH)); Rectangle(hdc, ptBeg.x, ptBeg.y, ptEnd.x, ptEnd.y); } EndPaint(hwnd, &ps); return 0; case WM_DESTROY: PostQuitMessage(0); return 0; } return DefWindowProc(hwnd, message, wParam, lParam); }
7.6 鼠标滚轮
（1）WM_MOUSEWHEEL发送给具有焦点的窗口（注意不一定是鼠标下面的窗口）
（2）lParam参数：鼠标位置的屏幕坐标
（3）wParam参数
|
高位字 |
低位字（标记位） |
|
增量（WHEEL_DELTA）=120或-120 |
指明鼠标按钮、Shift、Ctrl键的状态 |
（4）获得系统设置的滚轮每个增量滚动的行数：默认是3
SystemParametersInfo(SPI_GETWHEELSCROLLLINES, 0, &ulScrollLines, 0) ;
（5）每滚一行增量:iDeltaPerLine=WHEEL_DELTA/ ulScrollLines=120/3=40.
【SysMets4程序】
//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") };
//SysMets4.c
/*---------------------------------------------------- SYSMETS4.C -- System Metrics Display Program No. 4 (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("SysMets4"); 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. 4"), 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; ULONG ulScrollLines; static int iDeltaPerLine, iAccumDelta; //每行增量和累积增量 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; //继续执行下去。 case WM_SETTINGCHANGE: //获取鼠标滚轮每次滚动的行数 SystemParametersInfo(SPI_GETWHEELSCROLLLINES, 0, &ulScrollLines, 0); //ulScrollLine一般为3或0.WHEEL_DELTA=120 if (ulScrollLines) { iDeltaPerLine = WHEEL_DELTA / ulScrollLines; } else { iDeltaPerLine = 0; } return 0; case WM_MOUSEWHEEL: if (iDeltaPerLine == 0) break; iAccumDelta += (short)HIWORD(wParam); //累积增量=±120 //通过该循环，将iAccumDelta由120变为0 while (iAccumDelta >= iDeltaPerLine) { SendMessage(hwnd, WM_VSCROLL, SB_LINEUP, 0); iAccumDelta -= iDeltaPerLine; } //通过该循环，将iAccumDelta由-120变为0 while (iAccumDelta <= -iDeltaPerLine) // { SendMessage(hwnd, WM_VSCROLL, SB_LINEDOWN, 0); iAccumDelta += iDeltaPerLine; } 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); }
