CreateBitmap image is not printing on window - c++

Question

I need to load a bmp image from file and load image data into buffer and then create new image from it. (I have a reason for doing this way). I wrote a sample program to mimic my project scenario.
LRESULT CALLBACK WndProc(HWND hWnd, UINT Msg, WPARAM wParam, LPARAM lParam)
{
static BITMAP bm;
static HBITMAP bmpSource = NULL;
static HBITMAP hbmp=NULL;
static HDC hdcSource = NULL;
static HDC hdcDestination= NULL;
static PAINTSTRUCT ps;
BITMAPINFO bitmap_info[2] = {0};
if (Msg == WM_CREATE) {
bmpSource = (HBITMAP)LoadImage(NULL, L"bmp00004.bmp", IMAGE_BITMAP, 0, 0, LR_LOADFROMFILE );
GetObject(bmpSource, sizeof(BITMAP), &bm);
bitmap_info->bmiHeader.biSize = sizeof(bitmap_info->bmiHeader);
int ret = GetDIBits(hdcSource, bmpSource, 0, bm.bmHeight, NULL, bitmap_info,DIB_RGB_COLORS);
LPVOID *lpvBits = (LPVOID*) malloc(3*(bm.bmWidth * bm.bmHeight * sizeof(DWORD)));
int gotData = GetDIBits(hdcSource, bmpSource, 0,bm.bmHeight,lpvBits, bitmap_info, DIB_RGB_COLORS);
hbmp = (HBITMAP) CreateBitmap(bm.bmWidth, bm.bmHeight, bm.bmPlanes, bm.bmBitsPixel ,lpvBits);
hdcSource = CreateCompatibleDC(GetDC(0));
SelectObject(hdcSource, hbmp);
return 0;
}else if (Msg == WM_PAINT) {
hdcDestination = BeginPaint(hWnd, &ps);
BitBlt(hdcDestination, 0, 0,bm.bmWidth , bm.bmHeight, hdcSource, 0, 0, SRCCOPY);
EndPaint(hWnd, &ps);
return 0;
}else if (Msg == WM_DESTROY) {
DeleteDC(hdcSource);
EndPaint(hWnd, &ps);
DeleteObject(bmpSource);
DeleteObject(hbmp);
}
return DefWindowProc(hWnd, Msg, wParam, lParam);
}
I am expecting program to print the image on the window.
Now the newly created image is not displayed on window. All I can see is a gray box.

Answer 1

Your code can be considerably simplified. There is no need to call GetDIBits (which you are doing before you set up hdcSource anyway), and you should clean up properly and minimise the use of static variables. Something like the following (error checking omitted for clarity):
LRESULT CALLBACK WndProc(HWND hWnd, UINT Msg, WPARAM wParam, LPARAM lParam)
{
static HBITMAP bmpSource;
if (Msg == WM_CREATE) {
bmpSource = (HBITMAP)LoadImage(NULL, L"bmp00004.bmp", IMAGE_BITMAP, 0, 0, LR_LOADFROMFILE );
return 0;
}
if (Msg == WM_PAINT) {
PAINTSTRUCT ps;
HDC hdcDestination = BeginPaint(hWnd, &ps);
BITMAP bm;
GetObject(bmpSource, sizeof(bm), &bm);
HDC hdcSource = CreateCompatibleDC(hdcDestination);
HGDIOBJ hOldBmp = SelectObject(hdcSource, bmpSource);
BitBlt(hdcDestination, 0, 0,bm.bmWidth , bm.bmHeight, hdcSource, 0, 0, SRCCOPY);
SelectObject(hdcSource, hOldBmp);
DeleteDC(hdcSource);
EndPaint(hWnd, &ps);
return 0;
}
if (Msg == WM_DESTROY)
DeleteObject(bmpSource);
return DefWindowProc(hWnd, Msg, wParam, lParam);
}

Answer 2

It seems you are attempting to read a bitmap file and write to another HBITMAP handle, for whatever reason...
LoadImage returns a compatible bitmap (unless you specify LR_CREATEDIBSECTION), therefore you need CreateCompatibleBitmap followed by SetDIBits to duplicate that source bitmap.
For some reason you have declared BITMAPINFO bminfo[2] But you only need one bminfo object. You need new or malloc to allocate enough memory for one object. Note that you cannot randomly swap arrays for pointers and vice-versa. If you used a debugger you would notice the functions failed and bminfo was not properly filled.
It's easier if you setup BITMAPINFOHEADER yourself, rather than let GetDIBits fill that parameter:
LRESULT CALLBACK WndProc(HWND hWnd, UINT Msg, WPARAM wParam, LPARAM lParam)
{
static HDC hdc_memory;
static HBITMAP hbmp_src;
static HBITMAP hbmp_dst;
static BITMAP bm;
if(Msg == WM_CREATE)
{
hbmp_src = (HBITMAP)LoadImage(NULL, L"file.bmp",
IMAGE_BITMAP, 0, 0, LR_LOADFROMFILE);
HDC hdc = GetDC(0);
hdc_memory = CreateCompatibleDC(hdc);
GetObject(hbmp_src, sizeof(bm), &bm);
int w = bm.bmWidth;
int h = bm.bmHeight;
if(h < 0) h = -h;
int size = ((w * bm.bmBitsPixel + 31) / 32) * 4 * h;
BITMAPINFOHEADER bi = { sizeof(bi), w, h, bm.bmPlanes, bm.bmBitsPixel };
BYTE* bits = new BYTE[size];
GetDIBits(hdc, hbmp_src, 0, h, bits, (BITMAPINFO*)&bi, DIB_RGB_COLORS);
//change the pixel data in bits if that's your goal ...
hbmp_dst = CreateCompatibleBitmap(hdc, w, h);
SetDIBits(hdc, hbmp_dst, 0, h, bits, (BITMAPINFO*)&bi, DIB_RGB_COLORS);
SelectObject(hdc_memory, hbmp_dst);
delete[] bits;
ReleaseDC(0, hdc);
return 0;
}
else if(Msg == WM_PAINT)
{
PAINTSTRUCT ps;
HDC hdc = BeginPaint(hWnd, &ps);
BitBlt(hdc, 0, 0, bm.bmWidth, bm.bmHeight, hdc_memory, 0, 0, SRCCOPY);
EndPaint(hWnd, &ps);
return 0;
}
else if(Msg == WM_DESTROY)
{
DeleteDC(hdc_memory);
DeleteObject(hbmp_src);
DeleteObject(hbmp_dst);
PostQuitMessage(0);
return 0;
}
return DefWindowProc(hWnd, Msg, wParam, lParam);
}