From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 313CB1B4132; Mon, 14 Apr 2025 06:51:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744613479; cv=none; b=HIMCDgFcLqFP9u0+LwMj50Y50iz9sTd158Beh+Tzo/ZWwPLo7zdx6501pQ0f1fB7CHCojgXrKx1GXoyrQE0N2dSXE9RaI08fGMz2hWHx1N5W+EpvxM0RaL8g32ceHBG+hdhE8tr1KCYI732if1QWp+iv6mMbTs8tcriKgZiJJ2Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744613479; c=relaxed/simple; bh=asO4o657iz8nQe0uAHLA3O0c3AbaHXOjJNiLc6xpZcA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=HMHfZsC93BsozwfWQa0b5fFuco8eZq4QgEDRQ/MkzLC9MIJbMP7JP5tZCV2FBrwyrkAfZrnlDbWAJPb+6qyqfRmJ+0Qe9wQ7s81g3TQ1x8IlslqpnS3SuqPR1aTxNsk01WpOFJNA7XnWAD0MHkBrETQ55fb8PZuV8GupiYIj0z0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=gRzhjdBt; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="gRzhjdBt" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 54E56C4CEE2; Mon, 14 Apr 2025 06:51:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1744613478; bh=asO4o657iz8nQe0uAHLA3O0c3AbaHXOjJNiLc6xpZcA=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=gRzhjdBttm8QnvwtlyZLRah0rJfFxHQsMcux6mt8gjLRR7wn6z4IhVnMC3io9kMoN hfQrQiL2Z9iP7naqAxb58cx17/nO2yLRC2AfC4LHNaRtRac6/4N61YrmtOBxjtFW4g GmpSC26URPypH5WZT2HOhfSNyAhitQaxCQ8Rq8oPaFUv1EV+9DXynJ8EInc2NimXQU BYUxZUX3guQDbuugI0YjIFcDlpZ595xgQ6Fn/5OhDlaGQw9yZC0xJQUTuUVv19kjy8 YnC508i4MR4MtRhhn8XzAEW6263V4hjUfQ1cE3FCsqhwjKh0f2DGhaoed7fTYCjy4U rm8j+C9sxpoqw== Message-ID: <7fce92da-62d3-421d-9cd1-f9167c05d2b0@kernel.org> Date: Mon, 14 Apr 2025 08:51:15 +0200 Precedence: bulk X-Mailing-List: linux-serial@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 03/11] vt: properly support zero-width Unicode code points To: Nicolas Pitre , Greg Kroah-Hartman Cc: Nicolas Pitre , Dave Mielke , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org References: <20250410011839.64418-1-nico@fluxnic.net> <20250410011839.64418-4-nico@fluxnic.net> Content-Language: en-US From: Jiri Slaby Autocrypt: addr=jirislaby@kernel.org; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 10. 04. 25, 3:13, Nicolas Pitre wrote: > From: Nicolas Pitre > > Zero-width Unicode code points are causing misalignment in vertically > aligned content, disrupting the visual layout. Let's handle zero-width > code points more intelligently. ... > --- a/drivers/tty/vt/vt.c > +++ b/drivers/tty/vt/vt.c > @@ -443,6 +443,15 @@ static void vc_uniscr_scroll(struct vc_data *vc, unsigned int top, > } > } > > +static u32 vc_uniscr_getc(struct vc_data *vc, int relative_pos) > +{ > + int pos = vc->state.x + vc->vc_need_wrap + relative_pos; > + > + if (vc->vc_uni_lines && pos >= 0 && pos < vc->vc_cols) So that is: in_range(pos, 0, vc->vc_cols) right? > + return vc->vc_uni_lines[vc->state.y][pos]; > + return 0; > +} > + > static void vc_uniscr_copy_area(u32 **dst_lines, > unsigned int dst_cols, > unsigned int dst_rows, > @@ -2905,18 +2914,49 @@ static bool vc_is_control(struct vc_data *vc, int tc, int c) > return false; > } > > +static void vc_con_rewind(struct vc_data *vc) > +{ > + if (vc->state.x && !vc->vc_need_wrap) { > + vc->vc_pos -= 2; > + vc->state.x--; > + } > + vc->vc_need_wrap = 0; > +} > + > static int vc_con_write_normal(struct vc_data *vc, int tc, int c, > struct vc_draw_region *draw) > { > - int next_c; > + int next_c, prev_c; > unsigned char vc_attr = vc->vc_attr; > u16 himask = vc->vc_hi_font_mask, charmask = himask ? 0x1ff : 0xff; > u8 width = 1; > bool inverse = false; > > if (vc->vc_utf && !vc->vc_disp_ctrl) { > - if (ucs_is_double_width(c)) > + if (ucs_is_double_width(c)) { > width = 2; > + } else if (ucs_is_zero_width(c)) { > + prev_c = vc_uniscr_getc(vc, -1); > + if (prev_c == ' ' && > + ucs_is_double_width(vc_uniscr_getc(vc, -2))) { > + /* > + * Let's merge this zero-width code point with > + * the preceding double-width code point by > + * replacing the existing whitespace padding. > + */ > + vc_con_rewind(vc); > + } else if (c == 0xfe0f && prev_c != 0) { > + /* > + * VS16 (U+FE0F) is special. Let it have a > + * width of 1 when preceded by a single-width > + * code point effectively making the later > + * double-width. > + */ > + } else { > + /* Otherwise zero-width code points are ignored */ > + goto out; > + } > + } Please, extract this width evaluation to a separate function. ... > --- a/include/linux/consolemap.h > +++ b/include/linux/consolemap.h ... > @@ -63,6 +68,11 @@ static inline bool ucs_is_double_width(uint32_t cp) > { > return false; > } > + > +static inline bool ucs_is_zero_width(uint32_t cp) > +{ > + return false; > +} Again, is this necessary? thanks, -- js suse labs