How to change the background Image of a window in win32?

How I can change the background image of a window at runtime in WIN32?

I have created the window using CreateWindow(). Then I have a LoadImage Button which opens a model dialog box (open fil开发者_开发知识库e dialog)... Now I want to use the file name returned by this dialog box as the image of the window.

There is no native concept for the window background, you have to manually paint your image, usually in the WM_ERASEBKGND message. If you are using MFC you can check this article: http://www.codeproject.com/KB/graphics/picturewindow.aspx

A piece of sample code of what CoreyStup explains, in the window callback:

switch (message)
{
   case WM_CREATE:
   {
       HBITMAP hImage = (HBITMAP)LoadImage(NULL, L"guibg.bmp", IMAGE_BITMAP, 0, 0, LR_LOADFROMFILE);
       HWND hImageView = CreateWindowEx(NULL, L"STATIC", NULL, SS_BITMAP | WS_VISIBLE | WS_CHILD, 0, 00, 500, 600, hWnd, (HMENU)IMAGE_VIEW, GetModuleHandle(NULL), NULL);
       SendMessage(hImageView, STM_SETIMAGE, IMAGE_BITMAP, (LPARAM)hImage);
...

Credits also to fritzone who answered this on this similar thread: How to add picture box in win32 API using visual c++

NOTE: Use bitmaps generated by paint, otherwise LoadImage may return NULL without an error and the image will be invisible.

compile the code below.

write your file name in textbox and press change background.

i use mingw 4.7.

you can only use .bmp images, if you want to use other image you have to use GdiPluse.

#include <windows.h>

//variables
HWND hwnd01, label01;
HBITMAP hBitmap01 = NULL;

//functions
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);



int WINAPI WinMain( HINSTANCE hInstance, HINSTANCE hPrevInstance,
                LPSTR lpCmdLine, int nCmdShow )
{
MSG  msg ;
WNDCLASS wc = {0};
wc.lpszClassName = TEXT( "GUI01" );
wc.hInstance     = hInstance ;
wc.hbrBackground = GetSysColorBrush(COLOR_3DFACE);
wc.lpfnWndProc   = WndProc ;
wc.hCursor       = LoadCursor(0, IDC_ARROW);


RegisterClass(&wc);
hwnd01 = CreateWindow( wc.lpszClassName, TEXT("GUI01 Headline"),
            WS_OVERLAPPEDWINDOW | WS_VISIBLE,
            150, 150, 330, 150, 0, 0, hInstance, 0);

while( GetMessage(&msg, NULL, 0, 0)) {
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return (int) msg.wParam;
}

LRESULT CALLBACK WndProc( HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam )
{
switch(msg)
{
case WM_CREATE:
{
    CreateWindow(TEXT("button"), TEXT("Change Background"),
                 WS_VISIBLE | WS_CHILD ,
                 20, 50, 140, 25,
                 hwnd, (HMENU) 1, NULL, NULL);

    CreateWindow(TEXT("button"), TEXT("Quit"),
                 WS_VISIBLE | WS_CHILD ,
                 190, 50, 80, 25,
                 hwnd, (HMENU) 2, NULL, NULL);
    label01 = CreateWindow(TEXT("Edit"), TEXT("Label"),
                 WS_VISIBLE | WS_CHILD,
                 20, 10, 280, 25,
                 hwnd, (HMENU) 3, NULL, NULL);
    break;
}

  case WM_COMMAND:
  {
   if (LOWORD(wParam) == 1) {
       TCHAR* string01 = new TCHAR[300];

        GetWindowText(label01, string01, 300);
        hBitmap01 = (HBITMAP)LoadImage(NULL, string01, IMAGE_BITMAP, 0, 0, LR_LOADFROMFILE);

        if (hBitmap01==NULL) 
        MessageBox(NULL, "Error Loading Image.", "ERROR", MB_ICONWARNING | MB_DEFBUTTON2);
        else
        InvalidateRect(hwnd01, NULL, TRUE);
   }

   if (LOWORD(wParam) == 2) {
          PostQuitMessage(0);
   }

   break;
   }
case WM_PAINT:
{
    PAINTSTRUCT     ps01;
    HDC             hdc01;
    BITMAP          bitmap01;
    HDC             hdcMem01;
    HGDIOBJ         oldBitmap01;

    hdc01 = BeginPaint(hwnd01, &ps01);

    hdcMem01 = CreateCompatibleDC(hdc01);
    oldBitmap01 = SelectObject(hdcMem01, hBitmap01);

    GetObject(hBitmap01, sizeof(bitmap01), &bitmap01);
    BitBlt(hdc01, 0, 0, bitmap01.bmWidth, bitmap01.bmHeight, hdcMem01, 0, 0, SRCCOPY);

    SelectObject(hdcMem01, oldBitmap01);
    DeleteDC(hdcMem01);

    EndPaint(hwnd01, &ps01);

    break;
}

  case WM_DESTROY:
  {
     PostQuitMessage(0);
     break;
  }
}
return DefWindowProc(hwnd, msg, wParam, lParam);
}

A static control can have a background image (although its limited to bitmaps). You can put a child static control inside of your window (sized edge to edge) and set it as the background.

If you want fancy image handling like transparency, you'll need to do that manually.