第七章 鼠标part2

7.5拦截鼠标

一个窗口消息处理程序通常只在鼠标光标位于窗口的显示区域，或非显示区域上时才接收鼠标消息。所以应该只有当鼠标按键在您的显示区域中被按下时才拦截鼠标；当鼠标按键被释放时，才释放鼠标拦截。拦截鼠标并非只适用于那些古怪的应用程序。如果您需要鼠标按键在显示区域按下时都能够追踪WM_MOUSEMOVE消息，并直到鼠标按键被释放为止，那么您就应该拦截鼠标。

BLOKOUT2:

#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 ("Program requires Windows NT!"),szAppName, MB_ICONERROR) ;return 0 ;}hwnd = CreateWindow (szAppName, TEXT ("Mouse Button Demo"),WS_OVERLAPPEDWINDOW,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 ;}//画一个长方形void DrawBoxOutline (HWND hwnd, POINT ptBeg, POINT ptEnd){HDC hdc ;hdc = GetDC (hwnd) ; //该函数的主要的作用是根据nDrawMode设置的方式重新设定绘图的方式 //R2_BLACK Pixel is always black. //所有绘制出来的像素为黑色 //R2_NOT Pixel is the inverse of the screen color. //当前绘制的像素值设为屏幕像素值的反， //这样可以覆盖掉上次的绘图，（自动擦除上次绘制的图形） SetROP2 (hdc, R2_NOT) ;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){static BOOL fBlocking, fValidBox ;static POINT ptBeg, ptEnd, ptBoxBeg, ptBoxEnd ;HDC hdc ;PAINTSTRUCT ps ;switch (message){case WM_LBUTTONDOWN ://获取起点的坐标ptBeg.x = ptEnd.x = LOWORD (lParam) ;ptBeg.y = ptEnd.y = HIWORD (lParam) ;DrawBoxOutline (hwnd, ptBeg, ptEnd) ;//检查画出窗口：使窗口小于屏幕大小，开始在显示区域画出一块矩形，//然后将鼠标光标移出显示区域的右边或下边，最后释放鼠标按键。//程序将获得整个矩形的坐标。但是需要扩大窗口才能看清楚它。SetCapture(hwnd);//拦截鼠标//在这个函数呼叫之后，Windows将所有鼠标消息发给窗口句柄为hwnd的窗口消息处理程序。//之后收到鼠标消息都是以显示区域消息的型态出现，//即使鼠标正在窗口的非显示区域。lParam参数将指示鼠标在显示区域坐标中的位置。SetCursor(LoadCursor (NULL, IDC_CROSS));fBlocking = TRUE;return 0 ;case WM_MOUSEMOVE :if (fBlocking){SetCursor (LoadCursor (NULL, IDC_CROSS)) ;DrawBoxOutline (hwnd, ptBeg, ptEnd) ;//获取终点的坐标并画线ptEnd.x = LOWORD (lParam) ;ptEnd.y = HIWORD (lParam) ;DrawBoxOutline (hwnd, ptBeg, ptEnd) ;}return 0 ;case WM_LBUTTONUP ://左键弹起if (fBlocking){DrawBoxOutline (hwnd, ptBeg, ptEnd) ;ptBoxBeg = ptBeg ;ptBoxEnd.x = LOWORD (lParam) ;ptBoxEnd.y = HIWORD (lParam) ;//释放鼠标ReleaseCapture();SetCursor (LoadCursor (NULL, IDC_ARROW)) ;fBlocking = FALSE ;fValidBox = TRUE ;InvalidateRect (hwnd, NULL, TRUE) ;}return 0 ;case WM_CHAR :if ((fBlocking & wParam) == '/x1B') // i.e., Escape{DrawBoxOutline (hwnd, ptBeg, ptEnd) ;//释放鼠标ReleaseCapture();SetCursor (LoadCursor (NULL, IDC_ARROW)) ;fBlocking = FALSE ;}return 0 ;case WM_PAINT :hdc = BeginPaint (hwnd, &ps) ;if (fValidBox){SelectObject (hdc, GetStockObject (BLACK_BRUSH)) ;Rectangle ( hdc, ptBoxBeg.x, ptBoxBeg.y,ptBoxEnd.x, ptBoxEnd.y) ;}if (fBlocking){SetROP2 (hdc, R2_NOT) ;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鼠标滑轮

小滑轮的功能相当于鼠标按键的中键；或者您也可以用食指来转动它，这会产生一条特殊的消息，叫做WM_MOUSEWHEEL。收到WM_MOUSEWHEEL消息的时候，与平常一样，lParam将获得鼠标的位置，当然坐标是相对于屏幕左上角的，而不是显示区域的。
 另外，wParam的低字组包含一系列的旗标，用于表示鼠标按键、Shift与Ctrl键的状态。

SYSMETS5

#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 ("SysMets") ;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"),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 ;static int iDeltaPerLine, iAccumDelta ; // for mouse wheel logicHDC hdc ;int i, x, y, iVertPos, iHorzPos, iPaintBeg, iPaintEnd ;PAINTSTRUCT ps ;SCROLLINFO si ;TCHAR szBuffer[10] ;TEXTMETRIC tm ;ULONG ulScrollLines ; // for mouse wheel logicswitch (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 columnsiMaxWidth = 40 * cxChar + 22 * cxCaps ;// Fall through for mouse wheel informationcase WM_SETTINGCHANGE://SystemParametersInfo该函数查询或设置系统级参数。该函数也可以在设置参数中更新用户配置文件。//uiAction：该参数指定要查询或设置的系统级参数 SPI_GETWHEELSCROLLLINES获取滚动的行数//此值说明WHEEL_DELTA的delta值将滚动多少行//WHEEL_DELTA在WINUSER.H中定义,在内定情况下SystemParametersInfo传回3SystemParametersInfo (SPI_GETWHEELSCROLLLINES, 0, &ulScrollLines, 0) ;// ulScrollLines usually equals 3 or 0 (for no scrolling)// WHEEL_DELTA equals 120, so iDeltaPerLine will be 40if (ulScrollLines)iDeltaPerLine = WHEEL_DELTA / ulScrollLines ;elseiDeltaPerLine = 0 ;return 0 ;case WM_SIZE:cxClient = LOWORD (lParam) ;cyClient = HIWORD (lParam) ;// Set vertical scroll bar range and page sizesi.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 sizesi.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 vertical scroll bar informationsi.cbSize = sizeof (si) ;si.fMask = SIF_ALL ;GetScrollInfo (hwnd, SB_VERT, &si) ;// Save the position for comparison later oniVertPos = 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 ;//函数设置滚动条参数，包括滚动位置的最大值和最小值，页面大小，滚动按钮的位置。//如被请求，函数也可以重画滚动条。//hWnd：滚动条控制或带标准滚动条的窗体句柄，由fnBar参数决定。//fnBar：指定被设定参数的滚动条的类型。//IPBI：指向SCROLLINFO结构。//fRedraw：指定滚动条是否重画以反映滚动条的变化。TRUE，滚动条将被重画SetScrollInfo (hwnd, SB_VERT, &si, TRUE) ;GetScrollInfo (hwnd, SB_VERT, &si) ;// 如果位置发生了改变，滚动窗口并更新之if (si.nPos != iVertPos){//该函数滚动所指定的窗口客户区域内容。函数提供了向后兼容性//hWnd 客户区域将被滚动的窗口的句柄//XAmount 指定水平滚动的距离，以设备单位计。//YAmount 指定垂直滚动的距离，以设备单位计。//lpRect 该结构指定了将要滚动的客户区范围,NULL整个客户区域将被滚动。//lpClipRect NULL，则不会在滚动矩形上进行裁剪。ScrollWindow (hwnd, 0, cyChar * (iVertPos - si.nPos),NULL, NULL) ;UpdateWindow (hwnd) ;}return 0 ;case WM_HSCROLL:// Get all the vertical scroll bar informationsi.cbSize = sizeof (si) ;si.fMask = SIF_ALL ;// Save the position for comparison later onGetScrollInfo (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 windowif (si.nPos != iHorzPos){ScrollWindow (hwnd, cxChar * (iHorzPos - si.nPos), 0,NULL, NULL) ;}return 0 ;case WM_KEYDOWN :switch (wParam){case VK_HOME :SendMessage (hwnd, WM_VSCROLL, SB_TOP, 0) ;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_PAGEUP, 0) ;break ;case VK_RIGHT :SendMessage (hwnd, WM_HSCROLL, SB_PAGEDOWN, 0) ;break ;}return 0 ;case WM_MOUSEWHEEL://新的信息保存在wParam的高字组。其中有一个「delta」值，//该值目前可以是120或-120，这取决于滑轮的向前转动）还是向后转动。if (iDeltaPerLine == 0)break ; iAccumDelta += (short) HIWORD (wParam) ; // 120 or -120while (iAccumDelta >= iDeltaPerLine){SendMessage (hwnd, WM_VSCROLL, SB_LINEUP, 0) ;iAccumDelta -= iDeltaPerLine ;}while (iAccumDelta <= -iDeltaPerLine){SendMessage (hwnd, WM_VSCROLL, SB_LINEDOWN, 0) ;iAccumDelta += iDeltaPerLine ;}return 0 ;case WM_PAINT :hdc = BeginPaint (hwnd, &ps) ;// Get vertical scroll bar positionsi.cbSize = sizeof (si) ;si.fMask = SIF_POS ;GetScrollInfo (hwnd, SB_VERT, &si) ;iVertPos = si.nPos ;// Get horizontal scroll bar positionGetScrollInfo (hwnd, SB_HORZ, &si) ;iHorzPos = si.nPos ;// Find painting limitsiPaintBeg = 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) ; }