Function ImFontCalcTextSizeEx

external/imgui/imgui_draw.cpp:5661–5750

}

ImVec2 ImFontCalcTextSizeEx(ImFont* font, float size, float max_width, float wrap_width, const char* text_begin, const char* text_end_display, const char* text_end, const char** out_remaining, ImVec2* out_offset, ImDrawTextFlags flags)
{
    if (!text_end)
        text_end = text_begin + ImStrlen(text_begin); // FIXME-OPT: Need to avoid this.
    if (!text_end_display)
        text_end_display = text_end;

    ImFontBaked* baked = font->GetFontBaked(size);
    const float line_height = size;
    const float scale = line_height / baked->Size;

    ImVec2 text_size = ImVec2(0, 0);
    float line_width = 0.0f;

    const bool word_wrap_enabled = (wrap_width > 0.0f);
    const char* word_wrap_eol = NULL;

    const char* s = text_begin;
    while (s < text_end_display)
    {
        // Word-wrapping
        if (word_wrap_enabled)
        {
            // Calculate how far we can render. Requires two passes on the string data but keeps the code simple and not intrusive for what's essentially an uncommon feature.
            if (!word_wrap_eol)
                word_wrap_eol = ImFontCalcWordWrapPositionEx(font, size, s, text_end, wrap_width - line_width, flags);

            if (s >= word_wrap_eol)
            {
                if (text_size.x < line_width)
                    text_size.x = line_width;
                text_size.y += line_height;
                line_width = 0.0f;
                s = ImTextCalcWordWrapNextLineStart(s, text_end, flags); // Wrapping skips upcoming blanks
                if (flags & ImDrawTextFlags_StopOnNewLine)
                    break;
                word_wrap_eol = NULL;
                continue;
            }
        }

        // Decode and advance source
        const char* prev_s = s;
        unsigned int c = (unsigned int)*s;
        if (c < 0x80)
            s += 1;
        else
            s += ImTextCharFromUtf8(&c, s, text_end);

        if (c == '\n')
        {
            text_size.x = ImMax(text_size.x, line_width);
            text_size.y += line_height;
            line_width = 0.0f;
            if (flags & ImDrawTextFlags_StopOnNewLine)
                break;
            continue;
        }