Transparent 之 SetLayeredWindowAttributes

• 函数
  • The SetLayeredWindowAttributes function sets the opacity and transparency color key of a layered window.

  • BOOL SetLayeredWindowAttributes(          
        HWND hwnd,//Handle to the layered window
        COLORREF crKey,//specifies the transparency color key
        BYTE bAlpha,//describe the opacity of the layered window
        DWORD dwFlags//LWA_ALPHA | LWA_COLORKEY
    );

• 代码

  • 	static HBITMAP hBmp1;
    	static int cxBmp;
    	static int cyBmp;
    
    	case WM_CREATE:
    		{
    			//Set Window Attributes
    			SetWindowLong(hWnd,GWL_EXSTYLE,GetWindowLong(hWnd,GWL_EXSTYLE) | WS_EX_LAYERED);
    			SetLayeredWindowAttributes(hWnd,RGB(255,255,255),160,LWA_ALPHA);
    			//load bmp
    			hBmp1 = LoadBitmap(GetModuleHandle(NULL),MAKEINTRESOURCE(IDB_BITMAP1));
    			if (hBmp1 == NULL)
    			{
    				MessageBox(hWnd,L"failed to load bmp1!",NULL,MB_OK);
    			}
    			//get bmp info
    			BITMAP bmpInfo;
    			GetObject(hBmp1,sizeof(BITMAP),&bmpInfo);
    			cxBmp = bmpInfo.bmWidth;
    			cyBmp = bmpInfo.bmHeight;
    			//put window int the middle screen
    			int cxScr = GetSystemMetrics(SM_CXSCREEN);
    			int cyScr = GetSystemMetrics(SM_CYSCREEN);
    			int cxWnd = cxBmp + 2 * GetSystemMetrics(SM_CXFRAME);
    			int cyWnd = cyBmp + 2 * GetSystemMetrics(SM_CXFRAME) + GetSystemMetrics(SM_CYCAPTION);
    			MoveWindow(hWnd,(cxScr-cxWnd)/2,(cyScr-cyWnd)/2,cxWnd,cyWnd,TRUE);
    		}
    		break;
    
    	case WM_PAINT:
    		hdc = BeginPaint(hWnd, &ps);
    		{
    			//disp bmp
    			HDC hMemDC1 = CreateCompatibleDC(hdc);
    			SelectObject(hMemDC1, hBmp1);
    			BitBlt(hdc, 0, 0,cxBmp, cyBmp, hMemDC1, 0, 0, SRCCOPY);	
    			DeleteDC(hMemDC1);
    		}
    		EndPaint(hWnd, &ps);
    		break;
    

• 结果
  •