ImGui Bitfield Checkbox Matrix

imgui_bitfield.cpp

    bool BitField(const char* label, unsigned* bits, unsigned* hoverIndex)
    {
        unsigned val = *bits;

        ImGuiWindow* window = GetCurrentWindow();
        if (window->SkipItems)
            return false;

        unsigned oldFlags = window->Flags;
        ImGuiContext* g = ImGui::GetCurrentContext();
        const ImGuiStyle& style = ImGui::GetStyle();
        const ImGuiID id = window->GetID(label);
        const ImVec2 label_size = CalcTextSize(label, 0x0, true);
        const ImVec2 smallLabelSize = ImVec2(label_size.x * 0.5f, label_size.y * 0.5f);

        const float spacingUnit = 2.0f;

        bool anyPressed = false;
        ImVec2 currentPos = window->DC.CursorPos;
        for (unsigned i = 0; i < 32; ++i)
        {
            const void* lbl = (void*)(label + i);
            const ImGuiID localId = window->GetID(lbl);
            if (i == 16)
            {
                currentPos.x = window->DC.CursorPos.x;
                currentPos.y += smallLabelSize.y + style.FramePadding.y * 2 + spacingUnit /*little bit of space*/;
            }
            if (i == 8 || i == 24)
                currentPos.x += smallLabelSize.y;

            const ImRect check_bb(currentPos, { currentPos.x + smallLabelSize.y + style.FramePadding.y * 2, currentPos.y + smallLabelSize.y + style.FramePadding.y * 2 });

            bool hovered, held;
            bool pressed = ButtonBehavior(check_bb, localId, &hovered, &held, ImGuiButtonFlags_PressedOnClick);
            if (pressed)
                *bits ^= (1 << i);

            if (hovered && hoverIndex)
                *hoverIndex = i;

            RenderFrame(check_bb.Min, check_bb.Max, GetColorU32((held && hovered) ? ImGuiCol_FrameBgActive : hovered ? ImGuiCol_FrameBgHovered : ImGuiCol_FrameBg));
            if (*bits & (1 << i))
            {
                const float check_sz = ImMin(check_bb.GetWidth(), check_bb.GetHeight());
                const float pad = ImMax(spacingUnit, (float)(int)(check_sz / 4.0f));
                window->DrawList->AddRectFilled(
                { check_bb.Min.x + pad, check_bb.Min.y + pad },
                { check_bb.Max.x - pad, check_bb.Max.y - pad }, GetColorU32(ImGuiCol_CheckMark));
            }

            anyPressed |= pressed;
            currentPos.x = check_bb.Max.x + spacingUnit;
        }

        const ImRect matrix_bb(window->DC.CursorPos,
            { window->DC.CursorPos.x + (smallLabelSize.y + style.FramePadding.y * 2) * 16 /*# of checks in a row*/ + smallLabelSize.y /*space between sets of 8*/ + 15 * spacingUnit /*spacing between each check*/,
              window->DC.CursorPos.y + ((smallLabelSize.y + style.FramePadding.y * 2) * 2 /*# of rows*/ + spacingUnit /*spacing between rows*/) });

        ItemSize(matrix_bb, style.FramePadding.y);

        ImRect total_bb = matrix_bb;
        
        if (label_size.x > 0)
            SameLine(0, style.ItemInnerSpacing.x);

        const ImRect text_bb({ window->DC.CursorPos.x, window->DC.CursorPos.y + style.FramePadding.y }, { window->DC.CursorPos.x + label_size.x, window->DC.CursorPos.y + style.FramePadding.y + label_size.y });
        if (label_size.x > 0)
        {
            ItemSize(ImVec2(text_bb.GetWidth(), matrix_bb.GetHeight()), style.FramePadding.y);
            total_bb = ImRect(ImMin(matrix_bb.Min, text_bb.Min), ImMax(matrix_bb.Max, text_bb.Max));
        }

        if (!ItemAdd(total_bb, id))
            return false;

        if (label_size.x > 0.0f)
            RenderText(text_bb.GetTL(), label);

        window->Flags = oldFlags;
        return anyPressed;
    }