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 logic HDC hdc ; int i, x, y, iVertPos, iHorzPos, iPaintBeg, iPaintEnd ; PAINTSTRUCT ps ; SCROLLINFO si ; TCHAR szBuffer[10] ; TEXTMETRIC tm ; ULONG ulScrollLines ; // for mouse wheel logic 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 ; // Fall through for mouse wheel information case 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3 SystemParametersInfo (SPI_GETWHEELSCROLLLINES, 0, &ulScrollLines, 0) ; // ulScrollLines usually equals 3 or 0 (for no scrolling) // WHEEL_DELTA equals 120, so iDeltaPerLine will be 40 if (ulScrollLines) iDeltaPerLine = WHEEL_DELTA / ulScrollLines ; else iDeltaPerLine = 0 ; 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 vertical 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 ; //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 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_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 -120 while (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 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) ; }