GDI+ 文本绘图不一致

Question

I have a program that generates ASCII art from input image. The generated ASCII art is printed nicely in console. I have a function that also generates a PNG image with ASCII art using GDI+ . On my laptop, the generated image looks amazing and there is no problem.

However using that SAME code on my other computer the generated image is skewed and doesn't look any good and i have no idea why.

Note: For majority of my program i am using GDI+ , but for generating the image from my ASCII art i have to use GDI because i have to use raster font "Terminal" (which is available on any Windows machine), and GDI+ doesn't work with that font. I have a slight clue that hfont is somehow creating an issue because if passed 8x8px font the image looks almost fine.

The code of the function is:

VOID ASCIIFied::generate_image(VOID)
{
    if (this->decoded_art == nullptr)
    {
        cerr << "Failed to produce image from art because it's accessing nullptr reference maybe due to failed art generation or art isn't decoded yet.\nTerminating the program." << endl;
        exit(EXIT_FAILURE);
    }

    // In pixels, each letter is 8x12px + some breathing space (char_height = vertical amount of characters in art, chars_per_line = same but on horizontal axis)
    INT image_width  = this->chars_per_line * 8 + 100;
    INT image_height = this->char_height * 12 + 200;

    // Generate bitmap to draw to
    Bitmap art_output(image_width, image_height);
    Graphics g(&art_output);

    // Sets background to black
    Color color(Color::Black);
    g.Clear(color);

    // Creating proper font
    HFONT hfont = CreateFont(-8, -12, 0, 0, FW_NORMAL, FALSE, FALSE, FALSE, OEM_CHARSET, OUT_RASTER_PRECIS, CLIP_DEFAULT_PRECIS, PROOF_QUALITY, DEFAULT_PITCH, L"Terminal");

    // Text bounding rectangle
    RECT rc = { 50, 50, image_width,  image_height};

    HDC hdc = g.GetHDC();

    // Setting text background and foreground color to console colors along side with font
    SetBkColor(hdc, RGB(0, 0, 0));
    SetTextColor(hdc, RGB(210, 210, 210));

    // Apply font
    SelectObject(hdc, hfont);

    DrawTextA(hdc, this->decoded_art, -1, &rc, DT_LEFT | DT_TOP | DT_WORDBREAK);

    g.ReleaseHDC(hdc);
    DeleteObject(hfont);

    WCHAR path[MAX_PATH];

    // Get Desktop path
    if (SHGetFolderPathW(NULL, CSIDL_DESKTOPDIRECTORY, NULL, 0, path) != S_OK)
    {
        cerr << "DESKTOP path not found!\n";
        exit(EXIT_FAILURE);
    }

    SYSTEMTIME time_s;
    GetSystemTime(&time_s);

    wstring day    = to_wstring(time_s.wDay);
    wstring month  = to_wstring(time_s.wMonth);
    wstring year   = to_wstring(time_s.wYear);
    wstring hour   = to_wstring(time_s.wHour);
    wstring minute = to_wstring(time_s.wMinute);
    wstring second = to_wstring(time_s.wSecond);

    wstring image_path(path);
    image_path += L"\\ascii_art_" + day + L"-" + month + L"-" + year + L"-" + hour + L"-" + minute + L"-" + second + L".png";

    CLSID encId = { 0x557cf406, 0x1a04, 0x11d3,{ 0x9a, 0x73, 0x00, 0x00, 0xf8, 0x1e, 0xf3, 0x2e } };
    art_output.Save(image_path.c_str(), &encId);

    cout << "Image saved to your desktop." << endl;
}

Example of a good and bad image generation respectively ->

Good

Bad

Answer 1

The solution was quite simple and what was causing the problem was so easily overlooked.

On MSDN page for CreateFontW() function the first argument is font height , and then the second argument is font width .

From the provided code in my question, the bitmap width and height is calculated correctly for desired font (8x12px raster font Terminal)

// In pixels, each letter is 8x12px + some breathing space (char_height = vertical amount of characters in art, chars_per_line = same but on vertical axis)
INT image_width  = this->chars_per_line * 8 + 100;
INT image_height = this->char_height * 12 + 200;

But when actual font is created in the code, the order of arguments for font width and height is reversed when provided therefore the font mapper searches for wrong sized font which consequently won't fit when drawn in the created bitmap. IE:

 HFONT hfont = CreateFont(-8, -12, 0, 0, FW_NORMAL, FALSE, FALSE, FALSE, OEM_CHARSET, OUT_RASTER_PRECIS, CLIP_DEFAULT_PRECIS, PROOF_QUALITY, DEFAULT_PITCH, L"Terminal");

The solution was to switch -8 and -12 in the function call.