内存设备描述表的绘图技术--影子位图

/*----------------------------------------- SKETCH.C -- Shadow Bitmap Demonstration (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 ("Sketch") ; 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, TEXT ("Sketch"), WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, NULL, NULL, hInstance, NULL) ; if (hwnd == NULL) { MessageBox (NULL, TEXT ("Not enough memory to create bitmap!"), szAppName, MB_ICONERROR) ; return 0 ; } ShowWindow (hwnd, iCmdShow) ; UpdateWindow (hwnd) ; while (GetMessage (&msg, NULL, 0, 0)) { TranslateMessage (&msg) ; DispatchMessage (&msg) ; } return msg.wParam ; } void GetLargestDisplayMode (int * pcxBitmap, int * pcyBitmap) { DEVMODE devmode ; int iModeNum = 0 ; * pcxBitmap = * pcyBitmap = 0 ; ZeroMemory (&devmode, sizeof (DEVMODE)) ; devmode.dmSize = sizeof (DEVMODE) ; while (EnumDisplaySettings (NULL, iModeNum++, &devmode)) { * pcxBitmap = max (* pcxBitmap, (int) devmode.dmPelsWidth) ; * pcyBitmap = max (* pcyBitmap, (int) devmode.dmPelsHeight) ; } } LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam) { static BOOL fLeftButtonDown, fRightButtonDown ; static HBITMAP hBitmap ; static HDC hdcMem ; static int cxBitmap, cyBitmap, cxClient, cyClient, xMouse, yMouse ; HDC hdc ; PAINTSTRUCT ps ; switch (message) { case WM_CREATE: GetLargestDisplayMode (&cxBitmap, &cyBitmap) ; hdc = GetDC (hwnd) ; hBitmap = CreateCompatibleBitmap (hdc, cxBitmap, cyBitmap) ; hdcMem = CreateCompatibleDC (hdc) ; ReleaseDC (hwnd, hdc) ; if (!hBitmap) // no memory for bitmap { DeleteDC (hdcMem) ; return -1 ; } SelectObject (hdcMem, hBitmap) ; PatBlt (hdcMem, 0, 0, cxBitmap, cyBitmap, WHITENESS) ; return 0 ; case WM_SIZE: cxClient = LOWORD (lParam) ; cyClient = HIWORD (lParam) ; return 0 ; case WM_LBUTTONDOWN: if (!fRightButtonDown) SetCapture (hwnd) ; xMouse = LOWORD (lParam) ; yMouse = HIWORD (lParam) ; fLeftButtonDown = TRUE ; return 0 ; case WM_LBUTTONUP: if (fLeftButtonDown) SetCapture (NULL) ; fLeftButtonDown = FALSE ; return 0 ; case WM_RBUTTONDOWN: if (!fLeftButtonDown) SetCapture (hwnd) ; xMouse = LOWORD (lParam) ; yMouse = HIWORD (lParam) ; fRightButtonDown = TRUE ; return 0 ; case WM_RBUTTONUP: if (fRightButtonDown) SetCapture (NULL) ; fRightButtonDown = FALSE ; return 0 ; case WM_MOUSEMOVE: if (!fLeftButtonDown && !fRightButtonDown) return 0 ; hdc = GetDC (hwnd) ; SelectObject (hdc, GetStockObject (fLeftButtonDown ? BLACK_PEN : WHITE_PEN)) ; SelectObject (hdcMem, GetStockObject (fLeftButtonDown ? BLACK_PEN : WHITE_PEN)) ; MoveToEx (hdc, xMouse, yMouse, NULL) ; MoveToEx (hdcMem, xMouse, yMouse, NULL) ; xMouse = (short) LOWORD (lParam) ; yMouse = (short) HIWORD (lParam) ; LineTo (hdc, xMouse, yMouse) ; LineTo (hdcMem, xMouse, yMouse) ; ReleaseDC (hwnd, hdc) ; return 0 ; case WM_PAINT: hdc = BeginPaint (hwnd, &ps) ; BitBlt (hdc, 0, 0, cxClient, cyClient, hdcMem, 0, 0, SRCCOPY) ; EndPaint (hwnd, &ps) ; return 0 ; case WM_DESTROY: DeleteDC (hdcMem) ; DeleteObject (hBitmap) ; PostQuitMessage (0) ; return 0 ; } return DefWindowProc (hwnd, message, wParam, lParam) ; }

 

下面的代码与上面的代码运行效果一样，但代码还是略微有点不同，

也许下面的代码更能说明影子位图，更容易理解啥是影子位图吧

 

/*----------------------------------------- SKETCH.C -- Shadow Bitmap Demonstration (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 ("Sketch") ; 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, TEXT ("Sketch"), WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, NULL, NULL, hInstance, NULL) ; if (hwnd == NULL) { MessageBox (NULL, TEXT ("Not enough memory to create bitmap!"), szAppName, MB_ICONERROR) ; return 0 ; } ShowWindow (hwnd, iCmdShow) ; UpdateWindow (hwnd) ; while (GetMessage (&msg, NULL, 0, 0)) { TranslateMessage (&msg) ; DispatchMessage (&msg) ; } return msg.wParam ; } void GetLargestDisplayMode (int * pcxBitmap, int * pcyBitmap) { DEVMODE devmode ; int iModeNum = 0 ; * pcxBitmap = * pcyBitmap = 0 ; ZeroMemory (&devmode, sizeof (DEVMODE)) ; devmode.dmSize = sizeof (DEVMODE) ; while (EnumDisplaySettings (NULL, iModeNum++, &devmode)) { * pcxBitmap = max (* pcxBitmap, (int) devmode.dmPelsWidth) ; * pcyBitmap = max (* pcyBitmap, (int) devmode.dmPelsHeight) ; } } LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam) { static BOOL fLeftButtonDown, fRightButtonDown ; static HBITMAP hBitmap ; static HDC hdcMem ; static int cxBitmap, cyBitmap, cxClient, cyClient, xMouse, yMouse ; HDC hdc ; PAINTSTRUCT ps ; switch (message) { case WM_CREATE: GetLargestDisplayMode (&cxBitmap, &cyBitmap) ; hdc = GetDC (hwnd) ; hBitmap = CreateCompatibleBitmap (hdc, cxBitmap, cyBitmap) ; hdcMem = CreateCompatibleDC (hdc) ; ReleaseDC (hwnd, hdc) ; if (!hBitmap) // no memory for bitmap { DeleteDC (hdcMem) ; return -1 ; } SelectObject (hdcMem, hBitmap) ; PatBlt (hdcMem, 0, 0, cxBitmap, cyBitmap, WHITENESS) ; return 0 ; case WM_SIZE: cxClient = LOWORD (lParam) ; cyClient = HIWORD (lParam) ; return 0 ; case WM_LBUTTONDOWN: if (!fRightButtonDown) SetCapture (hwnd) ; xMouse = LOWORD (lParam) ; yMouse = HIWORD (lParam) ; fLeftButtonDown = TRUE ; return 0 ; case WM_LBUTTONUP: if (fLeftButtonDown) SetCapture (NULL) ; fLeftButtonDown = FALSE ; return 0 ; case WM_RBUTTONDOWN: if (!fLeftButtonDown) SetCapture (hwnd) ; xMouse = LOWORD (lParam) ; yMouse = HIWORD (lParam) ; fRightButtonDown = TRUE ; return 0 ; case WM_RBUTTONUP: if (fRightButtonDown) SetCapture (NULL) ; fRightButtonDown = FALSE ; return 0 ; case WM_MOUSEMOVE: if (!fLeftButtonDown && !fRightButtonDown) return 0 ; hdc = GetDC (hwnd) ; SelectObject (hdcMem, GetStockObject (fLeftButtonDown ? BLACK_PEN : WHITE_PEN)) ; MoveToEx (hdcMem, xMouse, yMouse, NULL) ; xMouse = (short) LOWORD (lParam) ; yMouse = (short) HIWORD (lParam) ; LineTo (hdcMem, xMouse, yMouse) ; InvalidateRect(hwnd,NULL,FALSE); ReleaseDC (hwnd, hdc) ; return 0 ; case WM_PAINT: hdc = BeginPaint (hwnd, &ps) ; BitBlt (hdc, 0, 0, cxClient, cyClient, hdcMem, 0, 0, SRCCOPY) ; EndPaint (hwnd, &ps) ; return 0 ; case WM_DESTROY: DeleteDC (hdcMem) ; DeleteObject (hBitmap) ; PostQuitMessage (0) ; return 0 ; } return DefWindowProc (hwnd, message, wParam, lParam) ; }