TextWrapped will cause too-many-vertices error for long single-line strings

[achabense]

Version/Branch of Dear ImGui:

Version 1.90.5

Back-ends:

imgui_impl_sdl2.cpp + imgui_impl_sdlrenderer2.cpp

Compiler, OS:

Windows 10 + MSVC 2022

Full config/build information:

No response

Details:

ImGui::TextWrapped and other text functions using wrap-pos settings will cause too-many-vertices error when displaying long single-line strings.

Background: I met this problem when trying to TextWrapped the lines getline-ed from files. I got the assertion failure after unexpectedly opening a large non-text file (which does not contain \n).
Similar issue: #5720

Screenshots/Video:

The effect for the first example below:

Minimal, Complete and Verifiable Example code:

ImGui::SetNextWindowSize(ImVec2(300, 50), ImGuiCond_Always);
if (ImGui::Begin("Failed")) {
    std::string long_single_line(20000, 'a');
    ImGui::TextWrapped("%s", long_single_line.c_str());
}
ImGui::End();

The problem is not limited to TextWrapped. It can affect every text function via wrap-pos settings:

ImGui::SetNextWindowSize(ImVec2(300, 50), ImGuiCond_Always);
if (ImGui::Begin("Failed")) {
    ImGui::PushTextWrapPos(200);
    std::string long_single_line(20000, 'a');
    ImGui::TextUnformatted(long_single_line.data(), long_single_line.data() + long_single_line.size());
    ImGui::PopTextWrapPos();
}
ImGui::End();

[ocornut]

Thanks. I have pushed a mitigation: daecfff

This is a known issue, I don't envision a fuller fix before we replace the text functions (the new WIP text functions don't have this issue). With the mitigation however you are much less likely to encounter the issue, so it may be good enough.

[ocornut]

Closing this as I don't expect to fix the current codebase further, but with the mitigation it's more or less not any worse that any other functions.

the new WIP text functions don't have this issue

Actually I was wrong, they also DID have this issue, but I have managed to fix it in the new text functions (no ETA, sorry) for a negligible cost (one pointer compare per visible wrapped line):