構造一個矩形位圖,位圖內有一個帶有陰影和紫色間隙的小球,程序使用定時器來控制小球的動做,其實是每當接收到定時器消息時將位圖經過BitBlt函數複製到客戶區,每當小球碰撞到客戶區上下左右四邊時就反彈回來。下面代碼有本人的理解註釋可供參考,本人才疏學淺,不妥請見諒。效果圖以下:
剛開始(初始實際上是在客戶區中心開始的,難截圖就隨便找張了,但理解就OK了,不礙事):
移動後:windows
#include<windows.h> #define ID_TIMER 1 LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam); int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR szCmdline, int iCmdShow) { static TCHAR szAppName[] = TEXT("Bounce"); HWND hWnd;//窗口句柄 MSG mSg;//消息結構體 //建立窗口類 WNDCLASSEX wndClass; //設置窗口類各種屬性 wndClass.cbSize = sizeof(WNDCLASSEX);//設置窗口類結構體大小 wndClass.cbClsExtra = 0;//窗口類尾部的一部分額外的空間 wndClass.cbWndExtra = 0; wndClass.hInstance = hInstance;//應用程序當前的實例句柄 wndClass.hCursor = LoadCursor(NULL, IDC_HELP); wndClass.hIcon = NULL; wndClass.hIconSm = NULL; wndClass.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH); wndClass.lpfnWndProc = WndProc;//回調函數的地址(窗口消息處理程序) wndClass.lpszClassName = szAppName;//窗口類的名字,也就是窗口的標識,後面用於建立窗口函數的參數。 wndClass.lpszMenuName = NULL;//菜單的名字,沒有爲NULL。 wndClass.style = CS_HREDRAW | CS_VREDRAW;//窗口類的樣式,它的值能夠是窗口樣式值的任意組合。CS_HREDRAW CS_VREDRAW,這個是垂直刷新和水平刷新,窗口尺寸改變,重畫活動區域。 //註冊對話框類 if (!RegisterClassEx(&wndClass)) { DWORD error_code = GetLastError(); MessageBox(NULL, TEXT("This program requires Windows NT!"), TEXT("NumRain"), MB_ICONERROR | MB_OKCANCEL); return 0; } hWnd = CreateWindow(szAppName, TEXT("The Hello Program"), WS_OVERLAPPEDWINDOW, 200, 200, 800, 500, NULL, NULL, hInstance, NULL); ShowWindow(hWnd, iCmdShow); UpdateWindow(hWnd); while (GetMessage(&mSg, NULL, 0, 0)) { TranslateMessage(&mSg); DispatchMessage(&mSg); } return (int)mSg.wParam; } LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam) { HDC hdc,hdcMem; HBRUSH hBrush; int iScale; static HBITMAP hBitmap; static int cxClient, cyClient,xCenter,yCenter,cxTotal,cyTotal,cxRadius,cyRadius,cxMove,cyMove,xPixel,yPixel; switch (message) { case WM_CREATE: //初始化數據 hdc = GetDC(hwnd); xPixel = GetDeviceCaps(hdc, ASPECTX);//36 yPixel = GetDeviceCaps(hdc, ASPECTY);//36 ReleaseDC(hwnd, hdc); SetTimer(hwnd, ID_TIMER, 50, NULL); return 0; case WM_SIZE: //客戶區中心的座標 xCenter = (cxClient = LOWORD(lParam)) / 2;//392 yCenter = (cyClient = HIWORD(lParam)) / 2;//230 iScale = min(cxClient*xPixel, cyClient*yPixel) / 16;//1037 //球水平的半徑和垂直的半徑 cxRadius = iScale / xPixel;//28 cyRadius = iScale / yPixel;//28 //球水平的半徑的一半和垂直的半徑的一半 cxMove = max(1, cxRadius / 2);//14 cyMove = max(1, cyRadius / 2);//14 //位圖寬和高 cxTotal = 2 * (cxRadius + cxMove);//84 cyTotal = 2 * (cyRadius + cyMove);//84 if (hBitmap) { DeleteObject(hBitmap); } hdc = GetDC(hwnd); //建立內存設備環境 hdcMem = CreateCompatibleDC(hdc); //建立與客戶區兼容的GDI位圖對象,該位圖寬爲cxTotal,高爲cyTotal hBitmap = CreateCompatibleBitmap(hdc, cxTotal, cyTotal); ReleaseDC(hwnd, hdc); //將GDI位圖對象選入內存設備環境,擴大了顯示錶面 SelectObject(hdcMem, hBitmap); //矩形的邊框被繪製在位圖以外 Rectangle(hdcMem, -1, -1, cxTotal + 1, cyTotal + 1); //建立陰影畫刷 hBrush = CreateHatchBrush(HS_DIAGCROSS, 0L); SelectObject(hdcMem, hBrush); //設置陰影畫刷間隔的空白處爲紫色 SetBkColor(hdcMem, RGB(255, 0, 255)); /* 將小球繪製在位圖的中心 值得注意的是,陰影畫刷和陰影間隙的紫色效果都是在Rectangle函數以後,說明只有球纔有陰影畫刷和紫色間隙,而球外面的邊空仍是白色的。 */ Ellipse(hdcMem, cxMove, cyMove, cxTotal - cxMove, cyTotal - cyMove); DeleteDC(hdcMem); DeleteObject(hBrush); return 0; case WM_TIMER: if (!hBitmap) { break; } hdc = GetDC(hwnd); //建立內存設備環境 hdcMem = CreateCompatibleDC(hdc); //將繪製好的位圖對象選入內存設備環境 SelectObject(hdcMem, hBitmap); //若是畫圖細心分析,會發現位圖中心,水平和垂直每移動cxMove個像素,都會有新的位圖覆蓋上一個位圖的球,這就不會出現球的殘影了 BitBlt(hdc, xCenter - cxTotal / 2, yCenter - cyTotal / 2, cxTotal, cyTotal, hdcMem, 0, 0, SRCCOPY); ReleaseDC(hwnd, hdc); DeleteDC(hdcMem); xCenter += cxMove; yCenter += cyMove; //客戶區左右兩邊的碰撞檢測 if ((xCenter + cxRadius >= cxClient) || (xCenter - cxRadius <= 0)) { //將小球反彈回去 cxMove = -cxMove; } if ((yCenter + cyRadius >= cyClient) || (yCenter - cyRadius <= 0)) { //將小球反彈回去 cyMove = -cyMove; } return 0; case WM_CLOSE: if (IDOK == MessageBox(hwnd, TEXT("是否退出?"), TEXT("對話框"), MB_OKCANCEL | MB_DEFBUTTON1 | MB_ICONQUESTION)) { DestroyWindow(hwnd); } else { return 0; } case WM_DESTROY: if (hBitmap) { DeleteObject(hBitmap); } KillTimer(hwnd, ID_TIMER); PostQuitMessage(0); return 0; } return DefWindowProc(hwnd, message, wParam, lParam); }