Attempt to Call separator_text_ex Causes Malformed Output

[Talbe1]

Hello,

I'm working on an application and wanted to use the separator text widget.
I tried limiting its width using a child but ended up causing misalignment with a Font Awesome icon I wanted to display to its right.

Then I attempted to make "customize" the separator text widget by calling the internal function myself:

from imgui_bundle import immapp, hello_imgui
from imgui_bundle import imgui


def _display_separator_text(label: str):
    if imgui.internal.get_current_window().skip_items:
        return

    imgui.internal.separator_text_ex(
        0,
        label,
        imgui.internal.find_rendered_text_end(label),
        0.0,
    )


def gui():
    label = "Hello world##some_id"

    _display_separator_text(label)


def main():
    runner_params = hello_imgui.RunnerParams()
    runner_params.callbacks.show_gui = gui

    immapp.run(runner_params)


if __name__ == "__main__":
        main()

This is the output on the screen I ended up with:

It seems that there's an out of bounds read issue. Perhaps due to the way binding is handled?
Judging by the fact that the end of the separator text is at the bottom left, it seems a significant amount of data was read.

I would like to know, should I submit a bug report? And if so, to who?

Here is some system information that might be helpful:
OS: Windows 11
Python: 3.10.11 (using .venv)
ImGui Bundle: 1.92.900

[Talbe1]

When I ran the same code again, it crashed without showing a window.
I replaced imgui.internal.find_rendered_text_end(label) with "##some_id" and got the application to run again, and show the same output.

[pthom]

This was a bug in the bindings: in C++, label_end must point inside label. A Python string cannot do that (it is always another buffer), so ImGui read from your label up to an unrelated address: garbage, then a crash.

It is fixed: separator_text_ex no longer takes a label_end, and shows the label up to its ##, as separator_text() does. Its extra_width reserves room after the label, where same_line() places your icon:

from imgui_bundle import imgui, icons_fontawesome_6 as fa

icon = fa.ICON_FA_GEAR
extra_width = imgui.calc_text_size(icon).x + imgui.get_style().item_spacing.x
imgui.internal.separator_text_ex(0, "Settings##some_id", extra_width)
imgui.same_line()
imgui.text(icon)

You can try it with the wheels built by the CI: https://github.com/pthom/imgui_bundle/actions/runs/38264073093
Until the next release, the public API can also do it, with the icon at the end of the line: a table, the separator in a stretching column and the icon in a fixed one.

if imgui.begin_table("##separator_and_icon", 2):
    imgui.table_setup_column("separator", imgui.TableColumnFlags_.width_stretch.value)
    imgui.table_setup_column("icon", imgui.TableColumnFlags_.width_fixed.value)
    imgui.table_next_column()
    imgui.separator_text("Settings")
    imgui.table_next_column()
    imgui.align_text_to_frame_padding()
    imgui.text(icon)
    imgui.end_table()

[Talbe1]

Hi,

Thank you very much for the fix. The separator_text_ex now works as expected with the new build.
My apologies for posting this bug in the Discussions instead of the Issues section.