Function ImFontAtlasPackGetRectSafe

src/imgui/imgui_draw.cpp:4370–4385

For user-facing functions: return NULL on invalid ID. Important: return pointer is valid until next call to AddRect(), e.g. FindGlyph(), CalcTextSize() can all potentially invalidate previous pointers.

// For user-facing functions: return NULL on invalid ID.
// Important: return pointer is valid until next call to AddRect(), e.g. FindGlyph(), CalcTextSize() can all potentially invalidate previous pointers.
ImTextureRect* ImFontAtlasPackGetRectSafe(ImFontAtlas* atlas, ImFontAtlasRectId id)
{
    if (id == ImFontAtlasRectId_Invalid)
        return NULL;
    int index_idx = ImFontAtlasRectId_GetIndex(id);
    if (atlas->Builder == NULL)
        ImFontAtlasBuildInit(atlas);
    ImFontAtlasBuilder* builder = (ImFontAtlasBuilder*)atlas->Builder;
    IM_MSVC_WARNING_SUPPRESS(28182); // Static Analysis false positive "warning C28182: Dereferencing NULL pointer 'builder'"
    if (index_idx >= builder->RectsIndex.Size)
        return NULL;
    ImFontAtlasRectEntry* index_entry = &builder->RectsIndex[index_idx];
    if (index_entry->Generation != ImFontAtlasRectId_GetGeneration(id) || !index_entry->IsUsed)
        return NULL;
    return &builder->Rects[index_entry->TargetIndex];
}

// Important! This assume by ImFontConfig::GlyphExcludeRanges[] is a SMALL ARRAY (e.g. <10 entries)
// Use "Input Glyphs Overlap Detection Tool" to display a list of glyphs provided by multiple sources in order to set this array up.