GDI:捕捉鼠标，实时改变矩形背景颜色。

转的高鑫的。

#include <windows.h>#include <math.h>#define NUM  10struct own_rectangle{int xLeft   ;int xRight  ;int yTop    ;int yBottom ;}rect[NUM];LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM);int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,PSTR szCmdLine, int iCmdShow){static TCHAR szAppName[] = TEXT("GDI：矩形颜色变换");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.lpszClassName = szAppName;wndclass.lpszMenuName  = NULL;if (!RegisterClass(&wndclass)){MessageBox(NULL, TEXT("Program requires Windows NT!"),szAppName, MB_ICONERROR) ;return 0;}hwnd = CreateWindow (szAppName, TEXT("Piano Demo Using Mouse"),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;}LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam){static int cxClient, cyClient;static int Flag[NUM] ={0,0,0,0,0,0,0,0,0,0};HDC hdc;static int i = 0,j;                                  //注意staticPAINTSTRUCT ps;                           //ps数组里面存放了RECT,用来重绘客户区的位置POINT hitPoint;int xStart = 200, yStart = 100, xEnd = 100, yEnd = 300;//HBRUSH hBrush;HPEN hPen;switch (message){case WM_SIZE:cxClient = LOWORD(lParam);cyClient = HIWORD(lParam);return 0;case WM_MOUSEMOVE:hitPoint.x = LOWORD(lParam);hitPoint.y = HIWORD(lParam);for (i = 0; i < NUM; i++)        {if (hitPoint.x >= rect[i].xLeft && hitPoint.x <= rect[i].xRight && hitPoint.y >= rect[i].yTop && hitPoint.y <= rect[i].yBottom )  {  Flag[i] = 1;  InvalidateRect(hwnd, NULL, TRUE);                                  //该函数向指定的窗口添加一个矩形。然后窗口客户区的这一部分将被重绘。为NULL，全部的窗口客户区域将被增加到更新区域中。break;  }}if (NUM == i)  InvalidateRect(hwnd, NULL, TRUE);    // 这两句确保光标不在矩形区域时能捕捉到信息的改变return 0;case WM_PAINT:hdc = BeginPaint (hwnd, &ps);  hPen = CreatePen (PS_SOLID, 1, RGB(255,0,0));  SelectObject (hdc, hPen);  //hBrush = (HBRUSH)GetStockObject (GRAY_BRUSH);  rect[0].xLeft    =  400   ;  rect[0].xRight   =  420   ;  rect[0].yTop     =  210    ;  rect[0].yBottom  =  300   ;  Rectangle(hdc, rect[0].xLeft, rect[0].yTop, rect[0].xRight, rect[0].yBottom);  for (j = 1; j < NUM; j++)  {  rect[j].xLeft    = rect[j-1].xLeft  + 20   ;  rect[j].xRight   = rect[j-1].xRight + 20   ;  rect[j].yTop     = rect[0].yTop            ;  rect[j].yBottom  = rect[0].yBottom         ;  Rectangle(hdc, rect[j].xLeft, rect[j].yTop, rect[j].xRight, rect[j].yBottom);  }  if (Flag[i] == 1)                {                            SelectObject(hdc, (HBRUSH)GetStockObject (GRAY_BRUSH));           Rectangle(hdc, rect[i].xLeft, rect[i].yTop, rect[i].xRight, rect[i].yBottom);  }  else if (NUM == i)                {  SelectObject(hdc, (HBRUSH)GetStockObject (WHITE_BRUSH));              Rectangle(hdc, rect[i].xLeft, rect[i].yTop, rect[i].xRight, rect[i].yBottom);  }  DeleteObject(hPen);  EndPaint(hwnd, &ps);return 0;case WM_DESTROY:PostQuitMessage (0);return 0;}return DefWindowProc (hwnd, message, wParam, lParam) ;}