Get assert while enable bitmap mode for freetype

[xyc19970716]

Version/Branch of Dear ImGui:

Version: 1.83 WIP
Branch: master

Back-end/Renderer/Compiler/OS

Back-ends: imgui_impl_opengl3.cpp + imgui_impl_glfw.cpp
Compiler: mingw64 gcc8.1.0
Operating System: windows 10 x64

My Issue/Question:

I use the clion to program my project. When i see the imgui_freetype.h/.cpp, it can enable bitmap mode. I want to use this function, but i get assert like next screenshot after i set like this pull 3879.

Screenshots/Video

Standalone, minimal, complete and verifiable example: (see #2261)

ImFontConfig font_config;
font_config.SizePixels = 13.0f;
font_config.FontBuilderFlags = ImGuiFreeTypeBuilderFlags_Bitmap;
io.Fonts->AddFontFromFileTTF("c:\\windows\\fonts\\msgothic.ttc", 13.0f, &font_config, io.Fonts->GetGlyphRangesJapanese());

[ocornut]

Hello,

If I try your code with my copy of msgothic.ttc (8780 KB) it works and I don't hit this assert.

Could you make those changes:

1. Replace the IM_ASSERT() with:

const FT_Bitmap* ft_bitmap = src_tmp.Font.RenderGlyphAndGetInfo(&src_glyph.Info);
if (ft_bitmap == NULL)
{
    printf("RenderGlyphAndGetInfo() failed for codepoint %04X\n", src_glyph.Codepoint);
    continue;
}

2. In RenderGlyphAndGetInfo() replace the error handling with:

if (error != 0)
{
    printf("RenderGlyphAndGetInfo() failed: %X \"%s\"\n", error, FT_Error_String(error));
    return NULL;
}

And then report on the glyphs (which glyphs are failing and why). Thank you!

[xyc19970716]

Thank you for your reply!
I test your code, and get many prints like this.

[ocornut]

0x13 in freetype is:

  FT_ERRORDEF_( Cannot_Render_Glyph,                         0x13,
                "cannot render this glyph format" )

What happen if you load this font AS A SECOND FONT (so first font work).

Then open Demo>Tools>Style Editor>Fonts> then Open your font
And look at the glyphes:

[xyc19970716]

Thank you! But what means AS A SECOND FONT? I just load this font.

[ocornut]

If you only load this font and all glyphes are missing you won’t be able to easily use the UI and use the viewer, that’s why as a second font the UI can use default font.

[xyc19970716]

Well, for your proposal, i get so few glyphs seeing on the editor.

Is my system font file broken, or the code version of FreeType wrong? But when no bitmap for FreeType, its font works well.

[ocornut]

Maybe try to update Freetype, you can too use vcpkg to install recent version of Freetype.

[xyc19970716]

Thanks a lot! I use FreeType by the implementation of vcpkg, that bitmap mode works well. But my project use cmake to install freetype, maybe i get mistake and i would fix it future.
I think this issue can be closed. Very thanks!