BITMAP Image won't load from file "INVALID HANDLE" - winapi

Question

This is basic, so only one snippet of code from the drawing function is needed because it has the info necessary about the
void draw()
{
RECT rect;
GetClientRect(hwnd, &rect);
HBITMAP FRAME1ANIMDASH = NULL;
FRAME1ANIMDASH = (HBITMAP) LoadImage(NULL, "Hidden but correct pathname that won't be shown here", 0, LR_DEFAULTSIZE, LR_DEFAULTSIZE, LR_CREATEDIBSECTION);
if(FRAME1ANIMDASH == NULL)
{
MessageBox(NULL, "CANNOT LOAD", "CANNOT LOAD", MB_OK);
}
HDC device;
PAINTSTRUCT ps;
BITMAP bm;
GetObject(FRAME1ANIMDASH,sizeof(BITMAP),&bm);
HDC hdcdevice=CreateCompatibleDC(device);
SelectObject(hdcdevice,FRAME1ANIMDASH);
BitBlt(device,0,0,0,0,hdcdevice,0,0,SRCCOPY);
UpdateWindow(hwnd);
device=GetDC(hwnd);
DeleteDC(hdcdevice);
DeleteObject((HBITMAP) FRAME1ANIMDASH);
DWORD lastError = GetLastError();
cout << GetLastError();
}
Get last error shows error 6, which is an invalid file handle. The message box shows up, which means the image never loaded and failed, so the code after it is not the primary concern yet.
I am trying to load a bitmap and put it on the Win32 window I have created.
No other code is needed, as there's nothing specific about any other code that would lead to a possible answer overall. Tell me what I can do to make the image load successfully.

Answer 1

You are calling GetLastError() too late. The error code is meaningless at that point as it could be overwritten by any of the other functions you are calling. You must call GetLastError() immediately after LoadImage() fails:
HBITMAP FRAME1ANIMDASH = (HBITMAP) LoadImage(...);
if (FRAME1ANIMDASH == NULL)
{
DWORD lastError = GetLastError();
cout << "CANNOT LOAD IMAGE, ERROR " << lastError;
MessageBox(NULL, "CANNOT LOAD IMAGE", "CANNOT LOAD IMAGE", MB_OK);
return; // <-- add this, too!
}
And the reason why LoadImage() is failing is because you are not specifying the LR_LOADFROMFILE flag, and not requesting the image size correctly, per the LoadImage() documentation:
lpszName [in]
...
If the hinst parameter is NULL and the fuLoad parameter omits the LR_LOADFROMFILE value, the lpszName specifies the OEM image to load. The OEM image identifiers are defined in Winuser.h and have the following prefixes.
...
If the fuLoad parameter includes the LR_LOADFROMFILE value, lpszName is the name of the file that contains the stand-alone resource (icon, cursor, or bitmap file). Therefore, set hinst to NULL.
...
cxDesired [in]
...
... If this parameter is zero and LR_DEFAULTSIZE is not used, the function uses the actual resource width.
...
cyDesired [in]
...
... If this parameter is zero and LR_DEFAULTSIZE is not used, the function uses the actual resource height.
...
fuLoad [in]
...
LR_DEFAULTSIZE
... If this flag is not specified and cxDesired and cyDesired are set to zero, the function uses the actual resource size.
...
LR_LOADFROMFILE
... Loads the stand-alone image from the file specified by lpszName (icon, cursor, or bitmap file).
So it should look more like this:
HBITMAP FRAME1ANIMDASH = (HBITMAP) LoadImage(NULL, "pathname", IMAGE_BITMAP, 0, 0, LR_CREATEDIBSECTION | LR_LOADFROMFILE);
Once you fix that, there are other problems with the code.
You are calling CreateCompatibleDC() with an uninitialized HDC variable, and not checking the result of CreateCompatibleDC() for failure. Your call to GetDC() is in the wrong place, it needs to be moved above CreateCompatibleDC(). And you are leaking the HDC that GetDC() returns, you need to call ReleaseDC() to free it.
You are also telling BitBlt() to copy a 0x0 rectangle of pixels, instead of using the true dimensions of the bitmap from the BITMAP structure, or even the window RECT that you are retrieving from GetClientRect().
Try something more like this instead:
void draw()
{
HBITMAP FRAME1ANIMDASH = (HBITMAP) LoadImage(NULL, "pathname", IMAGE_BITMAP, 0, 0, LR_CREATEDIBSECTION | LR_LOADFROMFILE);
if (FRAME1ANIMDASH == NULL)
{
DWORD lastError = GetLastError();
cout << "CANNOT LOAD IMAGE, ERROR " << lastError;
MessageBox(NULL, "CANNOT LOAD IMAGE", "CANNOT LOAD IMAGE", MB_OK);
return;
}
HDC hdcWnd = GetDC(hwnd);
if (hdcWnd === NULL)
{
DeleteObject(FRAME1ANIMDASH);
cout << "CANNOT GET WINDOW DC";
MessageBox(NULL, "CANNOT GET WINDOW DC", "CANNOT GET DC", MB_OK);
return;
}
HDC hdcMem = CreateCompatibleDC(hdcWnd);
if (hdcMem == NULL)
{
ReleaseDC(hwnd, hdcWnd);
DeleteObject(FRAME1ANIMDASH);
cout << "CANNOT CREATE COMPATIBLE DC";
MessageBox(NULL, "CANNOT CREATE COMPATIBLE DC", "CANNOT CREATE DC", MB_OK);
return;
}
BITMAP bm;
GetObject(FRAME1ANIMDASH, sizeof(BITMAP), &bm);
HBITMAP oldBm = (HBITMAP) SelectObject(hdcMem, FRAME1ANIMDASH);
BitBlt(hdcWnd, 0, 0, bm.bmWidth, bm.bmHeight, hdcMem, 0, 0, SRCCOPY);
SelectObject(hdcMem, oldBm);
DeleteDC(hdcMem);
ReleaseDC(hwnd, hdcWnd);
DeleteObject(FRAME1ANIMDASH);
UpdateWindow(hwnd);
}
That being said, the PAINTSTRUCT variable implies that your code is being used inside of a WM_PAINT message handler. If that is true, you should be using BeginPaint() instead of GetDC() to get the target HDC to draw on:
case WM_PAINT:
{
PAINTSTRUCT ps;
HDC hdc = BeginPaint(hwnd, &ps);
draw(hdc);
EndPaint(hwnd, &ps);
break;
};
void draw(HDC hdcTarget)
{
HBITMAP FRAME1ANIMDASH = (HBITMAP) LoadImage(NULL, "pathname", IMAGE_BITMAP, 0, 0, LR_CREATEDIBSECTION | LR_LOADFROMFILE);
if (FRAME1ANIMDASH == NULL)
{
DWORD lastError = GetLastError();
cout << "CANNOT LOAD IMAGE, ERROR " << lastError;
// DO NOT use MessageBox() in a WM_PAINT handler,
// You will trigger an endless re-paint loop!
return;
}
HDC hdcMem = CreateCompatibleDC(hdcTarget);
if (hdcMem == NULL)
{
DeleteObject(FRAME1ANIMDASH);
cout << "CANNOT CREATE COMPATIBLE DC";
return;
}
BITMAP bm;
GetObject(FRAME1ANIMDASH, sizeof(BITMAP), &bm);
HBITMAP oldBm = (HBITMAP) SelectObject(hdcMem, FRAME1ANIMDASH);
BitBlt(hdcWnd, 0, 0, bm.bmWidth, bm.bmHeight, hdcMem, 0, 0, SRCCOPY);
SelectObject(hdcMem, oldBm);
DeleteDC(hdcMem);
DeleteObject(FRAME1ANIMDASH);
}
Otherwise, if you are using your code outside of WM_PAINT, then the code is pretty much useless because UpdateWindow() will trigger a re-paint that erases your drawing. Persistent drawings on a window must be done using WM_PAINT (unless you are using UpdateLayeredWindow() with a WS_EX_LAYERED window).