UpdateLayeredWindow.cpp

#define _WIN32_WINNT 0x0501
#define WINVER 0x0501

#include <windows.h>
#include <commctrl.h>
#include <stdio.h>
#include <gdiplus.h>
using namespace Gdiplus;
#pragma comment(lib, "gdiplus.lib")
#pragma comment(lib, "Ole32.lib")

#pragma comment(lib, "user32.lib")
#pragma comment(lib, "comctl32.Lib")
#pragma comment(lib, "gdi32.Lib")

#pragma comment(linker, "\"/manifestdependency:type='Win32' name='Microsoft.Windows.Common-Controls' version='6.0.0.0' processorArchitecture='X86' publicKeyToken='6595b64144ccf1df' language='*'\"")



/*  Declare Windows procedure  */
LRESULT CALLBACK WindowProcedure (HWND, UINT, WPARAM, LPARAM);

/*  Make the class name into a global variable  */
char szClassName[ ] = "PNGDialog";

int WINAPI WinMain (HINSTANCE hThisInstance,
					HINSTANCE hPrevInstance,
					LPSTR lpszArgument,
					int nCmdShow)
{

	/**/
	/*  GDI+ startup token */
	ULONG_PTR gdiplusStartupToken;
	Gdiplus::GdiplusStartupInput gdiInput;
	Gdiplus::GdiplusStartup(&gdiplusStartupToken,&gdiInput,NULL);
	MSG messages;            /* Here messages to the application are saved */
	{
		/**/
		HWND hwnd;               /* This is the handle for our window */
		WNDCLASSEX wincl;        /* Data structure for the windowclass */

		/* The Window structure */
		wincl.hInstance = hThisInstance;
		wincl.lpszClassName = szClassName;//+-69+
		wincl.lpfnWndProc = WindowProcedure;      /* This function is called by windows */
		wincl.style = CS_DBLCLKS;                 /* Catch double-clicks */
		wincl.cbSize = sizeof (WNDCLASSEX);

		/* Use default icon and mouse-pointer */
		wincl.hIcon = LoadIcon (NULL, IDI_APPLICATION);
		wincl.hIconSm = LoadIcon (NULL, IDI_APPLICATION);
		wincl.hCursor = LoadCursor (NULL, IDC_ARROW);
		wincl.lpszMenuName = NULL;                 /* No menu */
		wincl.cbClsExtra = 0;                      /* No extra bytes after the window class */
		wincl.cbWndExtra = 0;                      /* structure or the window instance */
		/* Use Windows's default colour as the background of the window */
		wincl.hbrBackground = (HBRUSH) COLOR_BACKGROUND;

		/* Register the window class, and if it fails quit the program */
		if (!RegisterClassEx (&wincl))
			return 0;

		/* The class is registered, let's create the program*/
		hwnd = CreateWindowEx (
			WS_EX_LAYERED|WS_EX_TOPMOST|WS_EX_APPWINDOW,                   /* Extended possibilites for variation */
			szClassName,         /* Classname */
			"PNG transparent",       /* Title Text */
			WS_OVERLAPPEDWINDOW, /* default window */
			CW_USEDEFAULT,       /* Windows decides the position */
			CW_USEDEFAULT,       /* where the window ends up on the screen */
			500,                 /* The programs width */
			500,                 /* and height in pixels */
			HWND_DESKTOP,        /* The window is a child-window to desktop */
			NULL,                /* No menu */
			hThisInstance,       /* Program Instance handler */
			NULL                 /* No Window Creation data */
			);

		/* Make the window visible on the screen */
		ShowWindow (hwnd, nCmdShow);


		/********************************************
		*   step 1.
		*   Using Gdiplus to load the image
		********************************************/
		RECT wndRect;
		::GetWindowRect(hwnd,&wndRect);
		SIZE wndSize = {wndRect.right-wndRect.left,wndRect.bottom-wndRect.top};
		HDC hdc = ::GetDC(hwnd);
		HDC memDC = ::CreateCompatibleDC(hdc);
		HBITMAP memBitmap = ::CreateCompatibleBitmap(hdc,wndSize.cx,wndSize.cy);
		::SelectObject(memDC,memBitmap);

		Gdiplus::Image image(L"back.png");
		Gdiplus::Graphics graphics(memDC);
		graphics.DrawImage(&image,0,0,wndSize.cx,wndSize.cy);

		HDC screenDC = GetDC(NULL);
		POINT ptSrc = {0,0};

		/*********************************************
		*   step 3.
		*   Use UpdateLayeredWindow to Draw the Window
		*
		*********************************************/
		BLENDFUNCTION blendFunction;
		blendFunction.AlphaFormat = AC_SRC_ALPHA;
		blendFunction.BlendFlags = 0;
		blendFunction.BlendOp = AC_SRC_OVER;
		blendFunction.SourceConstantAlpha = 128;
		::UpdateLayeredWindow(hwnd,screenDC,&ptSrc,&wndSize,memDC,&ptSrc,0,&blendFunction,2);

		::DeleteDC(memDC);
		::DeleteObject(memBitmap);

		/* Run the message loop. It will run until GetMessage() returns 0 */
		while (GetMessage (&messages, NULL, 0, 0))
		{
			/* Translate virtual-key messages into character messages */
			TranslateMessage(&messages);
			/* Send message to WindowProcedure */
			DispatchMessage(&messages);
		}
	}
	Gdiplus::GdiplusShutdown(gdiplusStartupToken);
	/* The program return-value is 0 - The value that PostQuitMessage() gave */
	return messages.wParam;
}


/*  This function is called by the Windows function DispatchMessage()  */

LRESULT CALLBACK WindowProcedure (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
	switch (message)                  /* handle the messages */
	{
	case WM_DESTROY:
		PostQuitMessage (0);       /* send a WM_QUIT to the message queue */
		break;
	case WM_LBUTTONDOWN:
		printf("LButtonDown");
		//::PostMessage(hwnd,WM_NCLBUTTONDOWN,HTCAPTION,lParam);
		break;
	default:                      /* for messages that we don't deal with */
		return DefWindowProc (hwnd, message, wParam, lParam);
	}
	return 0;
}