Quickest way to get dimensions of BITMAP file

Question

What's the quickest way to get the height and width of a bitmap file in C? I either need to get it from the HBITMAP or the file itself, either way will work. Here's a section of my code:

    printf("Initializing textures...");
    HDC bp, memdc;
    HBITMAP bmp, hold;
    bp = GetDC(hwnd);
    memdc = CreateCompatibleDC(bp);
    bmp = (HBITMAP)LoadImage(NULL, tex_name, IMAGE_BITMAP, 0,0, LR_LOADFROMFILE);
    hold = (HBITMAP) SelectObject(memdc, bmp);
    for(int i = 0; i < 150; i++){
        for(int j = 0; j < 150; j++){
            COLORREF co = GetPixel(memdc, j, i);
            texturemap[i][j] = (COLORREF) (GetRValue(co)<<16)|(GetGValue(co)<<8)|GetBValue(co);
        }
    }
    SelectObject(memdc, hold);
    DeleteObject(bmp);
    DeleteDC(bp);
    system("cls");

It loads the pixel data from a file and then stores it into a 2d array. I would like to replace the 150 in each loop with the height followed by the width, but I have no clue how to get them.

(Also, yes I have already looked for existing answers.)

It should be in the BITMAP object you can reference this way: https://stackoverflow.com/questions/48754660/given-an-hbitmap-is-there-any-way-to-find-out-whether-it-contains-an-alpha-cha . Obscure, and for some reason you are the first person to ask this question! I wonder if Raymond Chen will show up. — user253751, Aug 16 '22 at 19:22
Don't forget to take the stride into account when parsing the image data. The row length in bytes is always a multiple of 4 which is >= `colour_byte_depth * bm.bmWidth`. — Weather Vane, Aug 16 '22 at 19:26

score 4 · Accepted Answer · answered Aug 16 '22 at 19:23

You could use GetObject to fetch the information, which is written to a BITMAP structure:

bmp = (HBITMAP)LoadImage(NULL, tex_name, IMAGE_BITMAP, 0,0, LR_LOADFROMFILE);

BITMAP bm;
GetObject(bmp, (int) sizeof bm, &bm);

for(LONG i = 0; i < bm.bmHeight; i++){
    for(LONG j = 0; j < bm.bmWidth; j++){
        // ...

Michael Chourdakis · Answer 2 · 2022-08-16T20:09:00.873

A newer way is using WIC which would also work for any sort of supported image.

static CComPtr<IWICImagingFactory> wbfact;
if (!wbfact)
    CoCreateInstance(CLSID_WICImagingFactory, 0, CLSCTX_INPROC_SERVER,__uuidof(IWICImagingFactory), (void**)&wbfact);
CComPtr<IWICBitmapDecoder> pDecoder = NULL;
CComPtr<IWICBitmapFrameDecode> pSource = NULL;
wbfact->CreateDecoderFromFilename(file,NULL, GENERIC_READ,WICDecodeMetadataCacheOnLoad,&pDecoder);
pDecoder->GetFrame(0, &pSource);
UINT w,h;
pSource->GetSize(&w,&h);

(Error handling omitted).

Yes, more lines of code but greater support of compression types and color formats, support for reading from memory and compatibility with Direct2D.

Nice solution, OP tagged the question C though – lulle2007200 Aug 16 '22 at 22:02 — lulle2007200, Aug 16 '22 at 22:02

Quickest way to get dimensions of BITMAP file

2 Answers2