Function InputTextReconcileUndoState

src/imgui/imgui_widgets.cpp:4469–4491

Find the shortest single replacement we can make to get from old_buf to new_buf Note that this doesn't directly alter state->TextA, state->TextLen. They are expected to be made valid separately. FIXME: Ideally we should transition toward (1) making InsertChars()/DeleteChars() update undo-stack (2) discourage (and keep reconcile) or obsolete (and remove reconcile) accessing buffer directly.

// Note that this doesn't directly alter state->TextA, state->TextLen. They are expected to be made valid separately.
// FIXME: Ideally we should transition toward (1) making InsertChars()/DeleteChars() update undo-stack (2) discourage (and keep reconcile) or obsolete (and remove reconcile) accessing buffer directly.
static void InputTextReconcileUndoState(ImGuiInputTextState* state, const char* old_buf, int old_length, const char* new_buf, int new_length)
{
    const int shorter_length = ImMin(old_length, new_length);
    int first_diff;
    for (first_diff = 0; first_diff < shorter_length; first_diff++)
        if (old_buf[first_diff] != new_buf[first_diff])
            break;
    if (first_diff == old_length && first_diff == new_length)
        return;

    int old_last_diff = old_length   - 1;
    int new_last_diff = new_length - 1;
    for (; old_last_diff >= first_diff && new_last_diff >= first_diff; old_last_diff--, new_last_diff--)
        if (old_buf[old_last_diff] != new_buf[new_last_diff])
            break;

    const int insert_len = new_last_diff - first_diff + 1;
    const int delete_len = old_last_diff - first_diff + 1;
    if (insert_len > 0 || delete_len > 0)
        if (IMSTB_TEXTEDIT_CHARTYPE* p = stb_text_createundo(&state->Stb->undostate, first_diff, delete_len, insert_len))
            for (int i = 0; i < delete_len; i++)
                p[i] = old_buf[first_diff + i];
}

// As InputText() retain textual data and we currently provide a path for user to not retain it (via local variables)
// we need some form of hook to reapply data back to user buffer on deactivation frame. (#4714)