win32用GDI+加载png图片作为背景图

#include <windows.h>
#include <gdiplus.h>

/* GDI+ startup token */
ULONG_PTR gdiplusStartupToken;

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

// UpdateLayeredWindow Defination
typedef BOOL(*UPDATELAYEREDWINDOWFUNCTION)(HWND,HDC,POINT*,SIZE*,HDC,POINT*,COLORREF,BLENDFUNCTION*,DWORD);

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

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

/**/
Gdiplus::GdiplusStartupInput gdiInput;
Gdiplus::GdiplusStartup(&gdiplusStartupToken,&gdiInput,NULL);
/**/
HWND hwnd; /* This is the handle for our window */
MSG messages; /* Here messages to the application are saved */
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_TOOLWINDOW, /* Extended possibilites for variation */
szClassName, /* Classname */
"PNGDialog Example Application", /* 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);
LONG style = ::GetWindowLong(hwnd,GWL_STYLE);
if(style&WS_CAPTION)
style^=WS_CAPTION;
if(style&WS_THICKFRAME)
style^=WS_THICKFRAME;
if(style&WS_SYSMENU)
style^=WS_SYSMENU;
::SetWindowLong(hwnd,GWL_STYLE,style);

style = ::GetWindowLong(hwnd,GWL_EXSTYLE);
if(style&WS_EX_APPWINDOW)
style^=WS_EX_APPWINDOW;
::SetWindowLong(hwnd,GWL_EXSTYLE,style);

/********************************************
* 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"pic.png");
Gdiplus::Graphics graphics(memDC);
graphics.DrawImage(&image,0,0,wndSize.cx,wndSize.cy);
/********************************************
* step 2.
* Get "UpdateLayeredWindow" function's
* proc address.
********************************************/
HMODULE hUser32 = ::LoadLibrary("User32.dll");
if(!hUser32)
{
return FALSE;
}
UPDATELAYEREDWINDOWFUNCTION UpdateLayeredWindow = (UPDATELAYEREDWINDOWFUNCTION)::GetProcAddress(hUser32,"UpdateLayeredWindow");
if(!UpdateLayeredWindow)
{
return FALSE;
}
// get screen dc
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 = 255;
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:
//::SendMessage(hwnd,WM_HIT)
break;
default: /* for messages that we don't deal with */
return DefWindowProc (hwnd, message, wParam, lParam);
}
return 0;
}

 

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