From: Byeongsik Jeon <bsjeon@hanmail.net>
Subject: Re: [PATCH 1/3] gdi32: Apply the more appropriate hinting flags.
Message-Id: <66ef9e22-a587-950f-3506-07c7193f32cb@hanmail.net>
Date: Tue, 29 Jan 2019 18:33:54 +0900
In-Reply-To: <20190125081339.10277-1-bsjeon@hanmail.net>
References: <20190125081339.10277-1-bsjeon@hanmail.net>

https://bugs.winehq.org/show_bug.cgi?id=46512#c7

Following these patches, I uploaded additional patches.

Byeongsik Jeon wrote:
> Wine-bug: https://bugs.winehq.org/show_bug.cgi?id=46512
> --
> 'ClearType compatible advance width'[1] is introduced by Microsoft to ensure
> that it is compatible with previous GRAY and B/W antialias metric. This can
> be specified as CLEARTYPE_QUALITY. Unfortunately, Freetype does not have
> 'ClearType compatible advance widths'[2].
> 
> So, we need to use FT_LOAD_TARGET_MONO to get the right advance value.
> Please note that this flag is a hinting flag, not a rendering flag.
> 
> FT_LOAD_TARGET_LCD can be used for CLEARTYPE_NATURAL_QUALITY [3].
> 
> [1]
> http://rastertragedy.com/RTRCh4.htm#Sec2
> 
> [2]
> Freetype interpreter V38(A.K.A. Infinality patch) is trying to implement it,
> but there are many bugs and no further improvements. This is not included in
> the default build option, and is documented as being deprecated in the future.
> 
> [3]
> With CLEARTYPE_NATURAL_QUALITY(ClearType natural advance widths), some legacy
> fonts are not ( integer ) linear with the advance width.
> To avoid the subpixel color blending problem between the small side-bearing
> characters, Microsoft seems to have modified the right-side-bearing.
> Also, there are issues that pointed out in [1].
> 
> This may be a text layout issue, but FT_LOAD_TARGET_LCD is still valid.
> To solve this, Wine need an additional advance correction patch, but it's
> not yet an interesting issue compared to other issues.
> 
> Signed-off-by: Byeongsik Jeon <bsjeon@hanmail.net>
> ---
>  dlls/gdi32/freetype.c | 23 ++++++++++-------------
>  1 file changed, 10 insertions(+), 13 deletions(-)
> 
> diff --git a/dlls/gdi32/freetype.c b/dlls/gdi32/freetype.c
> index c38108eece..85cff28c22 100644
> --- a/dlls/gdi32/freetype.c
> +++ b/dlls/gdi32/freetype.c
> @@ -6897,31 +6897,28 @@ static unsigned int get_bezier_glyph_outline(FT_Outline *outline, unsigned int b
>      return needed;
>  }
>  
> -static FT_Int get_load_flags( UINT format )
> +static FT_Int get_load_flags( UINT format, GdiFont *font )
>  {
> +    BOOL natural_width;
>      FT_Int load_flags = FT_LOAD_IGNORE_GLOBAL_ADVANCE_WIDTH;
>  
>      if (format & GGO_UNHINTED)
>          return load_flags | FT_LOAD_NO_HINTING;
>  
> +    natural_width = font->font_desc.lf.lfQuality == CLEARTYPE_NATURAL_QUALITY;
> +
>      switch (format & ~GGO_GLYPH_INDEX)
>      {
> -    case GGO_BITMAP:
> -        load_flags |= FT_LOAD_TARGET_MONO;
> -        break;
> -    case GGO_GRAY2_BITMAP:
> -    case GGO_GRAY4_BITMAP:
> -    case GGO_GRAY8_BITMAP:
> -    case WINE_GGO_GRAY16_BITMAP:
> -        load_flags |= FT_LOAD_TARGET_NORMAL;
> -        break;
>      case WINE_GGO_HRGB_BITMAP:
>      case WINE_GGO_HBGR_BITMAP:
> -        load_flags |= FT_LOAD_TARGET_LCD;
> +        load_flags |= natural_width ? FT_LOAD_TARGET_LCD : FT_LOAD_TARGET_MONO;
>          break;
>      case WINE_GGO_VRGB_BITMAP:
>      case WINE_GGO_VBGR_BITMAP:
> -        load_flags |= FT_LOAD_TARGET_LCD_V;
> +        load_flags |= natural_width ? FT_LOAD_TARGET_LCD_V : FT_LOAD_TARGET_MONO;
> +        break;
> +    default:
> +        load_flags |= FT_LOAD_TARGET_MONO;
>          break;
>      }
>  
> @@ -6947,7 +6944,7 @@ static DWORD get_glyph_outline(GdiFont *incoming_font, UINT glyph, UINT format,
>      FT_Vector adv;
>      INT origin_x = 0, origin_y = 0;
>      FT_Angle angle = 0;
> -    FT_Int load_flags = get_load_flags(format);
> +    FT_Int load_flags = get_load_flags(format, incoming_font);
>      double widthRatio = 1.0;
>      FT_Matrix transMat = identityMat;
>      FT_Matrix transMatUnrotated;
>