Creating a Label with Transparent Background

[dominicanjb]

Hey Everybody,

I'm a new convert from Visual Basic 6.0 to C++. I'd like to create a Windows app that cotains a label. I had success doing so using the "CreateWindow" function. However, I spent countless hours on the web trying to set the label background to transparent. The vast majority of what I read suggets that it should be handled via WM_CTLCOLORSTATIC message. However, it is not working for me. Here is the code:

// ProcFile.cpp : Defines the entry point for the application.
//

#include "stdafx.h"
#include "ProcFile.h"

#define MAX_LOADSTRING 100

// Global Variables:
HINSTANCE hInst;								// current instance
TCHAR szTitle[MAX_LOADSTRING];					// The title bar text
TCHAR szWindowClass[MAX_LOADSTRING];			// the main window class name

//Global Object variables
HWND btObj[2], lblObj;
HBRUSH windowBackgroundBrush;
COLORREF windowBackgroundColor; //Main Window color refs

// Forward declarations of functions included in this code module:
ATOM				MyRegisterClass(HINSTANCE hInstance);
BOOL				InitInstance(HINSTANCE, int);
LRESULT CALLBACK	WndProc(HWND, UINT, WPARAM, LPARAM);
INT_PTR CALLBACK	About(HWND, UINT, WPARAM, LPARAM);


void CreateObjects(HWND hWnd)
{
	//Buttons
	btObj[0] = CreateWindow(TEXT("button"),         //lpClassName = type of window to create
		                    TEXT("Process"),        //lpWindowName = Name that appears on the button
                            WS_VISIBLE | WS_CHILD,  //dwStyle = Window style flags
							408, 90,                // x and y coordinates of the button in pixels
							105, 33,                //width and height of the button in pixels
							hWnd,                   //hWndParent = handle of the parent or main window
							(HMENU) 1,              //Menu item ID = 1
							NULL, NULL);            //Set the last 2 params as null

	btObj[1] = CreateWindow(TEXT("button"),         //lpClassName = type of window to create
		                    TEXT("Quit"),           //lpWindowName = Name that appears on the button
                            WS_VISIBLE | WS_CHILD,  //dwStyle = Window style flags
							408, 130,                // x and y coordinates of the button in pixels
							105, 33,                //width and height of the button in pixels
							hWnd,                   //hWndParent = handle of the parent or main window
							(HMENU) 2,              //Menu item ID = 2
							NULL, NULL);            //Set the last 2 params as null

	//Labels
	lblObj =  CreateWindow(TEXT("edit"), TEXT("File: "), WS_VISIBLE | WS_CHILD, 16, 16, 490, 25, hWnd, (HMENU) 3, NULL, NULL);
	
}


int APIENTRY _tWinMain(HINSTANCE hInstance,
                     HINSTANCE hPrevInstance,
                     LPTSTR    lpCmdLine,
                     int       nCmdShow)
{
	UNREFERENCED_PARAMETER(hPrevInstance);
	UNREFERENCED_PARAMETER(lpCmdLine);

 	// TODO: Place code here.
	MSG msg;
	HACCEL hAccelTable;

	//The following two lines define the color of the main window and a brush to go with it
	windowBackgroundColor = RGB(0x0a, 0x00, 0xFE);
	windowBackgroundBrush = CreateSolidBrush(windowBackgroundColor); 

	// Initialize global strings
	LoadString(hInstance, IDS_APP_TITLE, szTitle, MAX_LOADSTRING);
	LoadString(hInstance, IDC_PROCFILE, szWindowClass, MAX_LOADSTRING);
	MyRegisterClass(hInstance);

	// Perform application initialization:
	if (!InitInstance (hInstance, nCmdShow))
	{
		return FALSE;
	}

	hAccelTable = LoadAccelerators(hInstance, MAKEINTRESOURCE(IDC_PROCFILE));

	// Main message loop:
	while (GetMessage(&msg, NULL, 0, 0))
	{
		if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg))
		{
			TranslateMessage(&msg);
			DispatchMessage(&msg);
		}
	}

	return (int) msg.wParam;
}



//
//  FUNCTION: MyRegisterClass()
//
//  PURPOSE: Registers the window class.
//
//  COMMENTS:
//
//    This function and its usage are only necessary if you want this code
//    to be compatible with Win32 systems prior to the 'RegisterClassEx'
//    function that was added to Windows 95. It is important to call this function
//    so that the application will get 'well formed' small icons associated
//    with it.
//
ATOM MyRegisterClass(HINSTANCE hInstance)
{
	WNDCLASSEX wcex;

	wcex.cbSize = sizeof(WNDCLASSEX);

	wcex.style			= CS_HREDRAW | CS_VREDRAW;
	wcex.lpfnWndProc	= WndProc;
	wcex.cbClsExtra		= 0;
	wcex.cbWndExtra		= 0;
	wcex.hInstance		= hInstance;
	wcex.hIcon			= LoadIcon(hInstance, MAKEINTRESOURCE(IDI_PROCFILE));
	wcex.hCursor		= LoadCursor(NULL, IDC_ARROW);
	//wcex.hbrBackground	= (HBRUSH)(COLOR_WINDOW+1);
	wcex.hbrBackground  = windowBackgroundBrush; //Use our custom background
	wcex.lpszMenuName	= MAKEINTRESOURCE(IDC_PROCFILE);
	wcex.lpszClassName	= szWindowClass;
	wcex.hIconSm		= LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_SMALL));

	return RegisterClassEx(&wcex);
}

//
//   FUNCTION: InitInstance(HINSTANCE, int)
//
//   PURPOSE: Saves instance handle and creates main window
//
//   COMMENTS:
//
//        In this function, we save the instance handle in a global variable and
//        create and display the main program window.
//
BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
{
   HWND hWnd;

   hInst = hInstance; // Store instance handle in our global variable

   hWnd = CreateWindow(szWindowClass, szTitle, WS_OVERLAPPEDWINDOW,
      CW_USEDEFAULT, 0, 535, 237, NULL, NULL, hInstance, NULL); //Modified width & height to 535 and 237 respectively

   if (!hWnd)
   {
      return FALSE;
   }

   ShowWindow(hWnd, nCmdShow);
   UpdateWindow(hWnd);

   return TRUE;
}

//
//  FUNCTION: WndProc(HWND, UINT, WPARAM, LPARAM)
//
//  PURPOSE:  Processes messages for the main window.
//
//  WM_COMMAND	- process the application menu
//  WM_PAINT	- Paint the main window
//  WM_DESTROY	- post a quit message and return
//
//
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
	int wmId, wmEvent;
	PAINTSTRUCT ps;
	HDC hdc;

	switch (message)
	{
	case WM_CREATE:
		CreateObjects(hWnd);
		break;
	case WM_COMMAND:
		wmId    = LOWORD(wParam);
		wmEvent = HIWORD(wParam);
		// Parse the menu selections:
		switch (wmId)
		{
		case IDM_ABOUT:
			DialogBox(hInst, MAKEINTRESOURCE(IDD_ABOUTBOX), hWnd, About);
			break;
		case IDM_EXIT:
			DestroyWindow(hWnd);
			break;
		default:
			return DefWindowProc(hWnd, message, wParam, lParam);
		}
		break;
	case WM_PAINT:
		hdc = BeginPaint(hWnd, &ps);
		// TODO: Add any drawing code here...
		EndPaint(hWnd, &ps);
		break;
	case WM_CTLCOLORSTATIC:
		if ( GetDlgItem(hWnd, 3) == (HWND)lParam)
		{
			SetBkMode( (HDC)wParam, TRANSPARENT);
			SetTextColor((HDC)wParam, RGB(255,0,0));
			return (BOOL) GetStockObject(HOLLOW_BRUSH);
		}
		//break;
	case WM_DESTROY:
		PostQuitMessage(0);
		break;
	default:
		return DefWindowProc(hWnd, message, wParam, lParam);
	}
	return 0;
}

// Message handler for about box.
INT_PTR CALLBACK About(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam)
{
	UNREFERENCED_PARAMETER(lParam);
	switch (message)
	{
	case WM_INITDIALOG:
		return (INT_PTR)TRUE;

	case WM_COMMAND:
		if (LOWORD(wParam) == IDOK || LOWORD(wParam) == IDCANCEL)
		{
			EndDialog(hDlg, LOWORD(wParam));
			return (INT_PTR)TRUE;
		}
		break;
	}
	return (INT_PTR)FALSE;
}

Help is much appreciated. BTW I'm using Visual Studio 2010.

Thanks,

DominicanJB

[dominicanjb]

Oops. Never mind. I found the error. I thought I was creating a label, but instead, I created a textbox. It should have been:
lblObj = CreateWindow(TEXT("static"), TEXT("File: "), WS_VISIBLE | WS_CHILD, 16, 16, 490, 25, hWnd, (HMENU) 3, NULL, NULL);

Thanks,

DominicanJB