textChanged

pub fn textChanged(self: *TextEntryWidget, start: usize, end: usize, added: i64) void {
    self.text_changed = true;
    if (end > self.text_changed_start) {
        // end is in current bytes, so we update it to previous frame's indexing
        var end_old: usize = undefined;
        if (self.text_changed_added >= 0) {
            end_old = end - @as(usize, @intCast(self.text_changed_added));
        } else {
            end_old = end + @as(usize, @intCast(-self.text_changed_added));
        }
        // This assumes that the current update happens after (in bytes) all
        // previous updates.  This is not exact, but will always give an
        // interval that includes all the updates.
        self.text_changed_end = @max(self.text_changed_end, end_old);
    } else {
        // before previous updates then indexing is the same
        self.text_changed_end = @max(self.text_changed_end, end);
    }

    // if we are before the previous updates then the indexing is the same
    self.text_changed_start = @min(self.text_changed_start, start);
    self.text_changed_added += added;

    if (self.textLayout.add_text_done) {
        self.edited_outside_last_frame.* = true;
    }

    //std.debug.print("textChanged {d} {d} {d}\n", .{ self.text_changed_start, self.text_changed_end, self.text_changed_added });
}