Function ImFontAtlasBuildInit

src/imgui/imgui_draw.cpp:4175–4216

Start packing over current empty texture

// Start packing over current empty texture
void ImFontAtlasBuildInit(ImFontAtlas* atlas)
{
    // Select Backend
    // - Note that we do not reassign to atlas->FontLoader, since it is likely to point to static data which
    //   may mess with some hot-reloading schemes. If you need to assign to this (for dynamic selection) AND are
    //   using a hot-reloading scheme that messes up static data, store your own instance of FontLoader somewhere
    //   and point to it instead of pointing directly to return value of the GetFontLoaderXXX functions.
    if (atlas->FontLoader == NULL)
    {
#ifdef IMGUI_ENABLE_FREETYPE
        atlas->SetFontLoader(ImGuiFreeType::GetFontLoader());
#elif defined(IMGUI_ENABLE_STB_TRUETYPE)
        atlas->SetFontLoader(ImFontAtlasGetFontLoaderForStbTruetype());
#else
        IM_ASSERT(0); // Invalid Build function
#endif
    }

    // Create initial texture size
    if (atlas->TexData == NULL || atlas->TexData->Pixels == NULL)
        ImFontAtlasTextureAdd(atlas, ImUpperPowerOfTwo(atlas->TexMinWidth), ImUpperPowerOfTwo(atlas->TexMinHeight));

    atlas->Builder = IM_NEW(ImFontAtlasBuilder)();
    if (atlas->FontLoader->LoaderInit)
        atlas->FontLoader->LoaderInit(atlas);

    ImFontAtlasBuildUpdateRendererHasTexturesFromContext(atlas);

    ImFontAtlasPackInit(atlas);

    // Add required texture data
    ImFontAtlasBuildUpdateLinesTexData(atlas);
    ImFontAtlasBuildUpdateBasicTexData(atlas);

    // Register fonts
    ImFontAtlasBuildUpdatePointers(atlas);

    // Update UV coordinates etc. stored in bound ImDrawListSharedData instance
    ImFontAtlasUpdateDrawListsSharedData(atlas);

    //atlas->TexIsBuilt = true;
}

// Destroy builder and all cached glyphs. Do not destroy actual fonts.
void ImFontAtlasBuildDestroy(ImFontAtlas* atlas)