kc3-lang/freetype/src/base/ftlcdfil.c

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• Hash : 08f66322
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  Date : 2021-06-08T18:23:16
  

  More various documentation improvements and fixes.

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• src/base/ftlcdfil.c

• /****************************************************************************
   *
   * ftlcdfil.c
   *
   *   FreeType API for color filtering of subpixel bitmap glyphs (body).
   *
   * Copyright (C) 2006-2021 by
   * David Turner, Robert Wilhelm, and Werner Lemberg.
   *
   * This file is part of the FreeType project, and may only be used,
   * modified, and distributed under the terms of the FreeType project
   * license, LICENSE.TXT.  By continuing to use, modify, or distribute
   * this file you indicate that you have read the license and
   * understand and accept it fully.
   *
   */
  
  
  #include <freetype/internal/ftdebug.h>
  
  #include <freetype/ftlcdfil.h>
  #include <freetype/ftimage.h>
  #include <freetype/internal/ftobjs.h>
  
  
  #ifdef FT_CONFIG_OPTION_SUBPIXEL_RENDERING
  
  /* define USE_LEGACY to implement the legacy filter */
  #define  USE_LEGACY
  
  #define FT_SHIFTCLAMP( x )  ( x >>= 8, (FT_Byte)( x > 255 ? 255 : x ) )
  
  
    /* add padding according to filter weights */
    FT_BASE_DEF( void )
    ft_lcd_padding( FT_BBox*        cbox,
                    FT_GlyphSlot    slot,
                    FT_Render_Mode  mode )
    {
      FT_Byte*                 lcd_weights;
      FT_Bitmap_LcdFilterFunc  lcd_filter_func;
  
  
      /* Per-face LCD filtering takes priority if set up. */
      if ( slot->face && slot->face->internal->lcd_filter_func )
      {
        lcd_weights     = slot->face->internal->lcd_weights;
        lcd_filter_func = slot->face->internal->lcd_filter_func;
      }
      else
      {
        lcd_weights     = slot->library->lcd_weights;
        lcd_filter_func = slot->library->lcd_filter_func;
      }
  
      if ( lcd_filter_func == ft_lcd_filter_fir )
      {
        if ( mode == FT_RENDER_MODE_LCD )
        {
          cbox->xMin -= lcd_weights[0] ? 43 :
                        lcd_weights[1] ? 22 : 0;
          cbox->xMax += lcd_weights[4] ? 43 :
                        lcd_weights[3] ? 22 : 0;
        }
        else if ( mode == FT_RENDER_MODE_LCD_V )
        {
          cbox->yMin -= lcd_weights[0] ? 43 :
                        lcd_weights[1] ? 22 : 0;
          cbox->yMax += lcd_weights[4] ? 43 :
                        lcd_weights[3] ? 22 : 0;
        }
      }
    }
  
  
    /* FIR filter used by the default and light filters */
    FT_BASE_DEF( void )
    ft_lcd_filter_fir( FT_Bitmap*           bitmap,
                       FT_LcdFiveTapFilter  weights )
    {
      FT_UInt   width  = (FT_UInt)bitmap->width;
      FT_UInt   height = (FT_UInt)bitmap->rows;
      FT_Int    pitch  = bitmap->pitch;
      FT_Byte*  origin = bitmap->buffer;
      FT_Byte   mode   = bitmap->pixel_mode;
  
  
      /* take care of bitmap flow */
      if ( pitch > 0 && height > 0 )
        origin += pitch * (FT_Int)( height - 1 );
  
      /* horizontal in-place FIR filter */
      if ( mode == FT_PIXEL_MODE_LCD && width >= 2 )
      {
        FT_Byte*  line = origin;
  
  
        /* `fir' must be at least 32 bit wide, since the sum of */
        /* the values in `weights' can exceed 0xFF              */
  
        for ( ; height > 0; height--, line -= pitch )
        {
          FT_UInt  fir[5];
          FT_UInt  val, xx;
  
  
          val    = line[0];
          fir[2] = weights[2] * val;
          fir[3] = weights[3] * val;
          fir[4] = weights[4] * val;
  
          val    = line[1];
          fir[1] = fir[2] + weights[1] * val;
          fir[2] = fir[3] + weights[2] * val;
          fir[3] = fir[4] + weights[3] * val;
          fir[4] =          weights[4] * val;
  
          for ( xx = 2; xx < width; xx++ )
          {
            val    = line[xx];
            fir[0] = fir[1] + weights[0] * val;
            fir[1] = fir[2] + weights[1] * val;
            fir[2] = fir[3] + weights[2] * val;
            fir[3] = fir[4] + weights[3] * val;
            fir[4] =          weights[4] * val;
  
            line[xx - 2] = FT_SHIFTCLAMP( fir[0] );
          }
  
          line[xx - 2] = FT_SHIFTCLAMP( fir[1] );
          line[xx - 1] = FT_SHIFTCLAMP( fir[2] );
        }
      }
  
      /* vertical in-place FIR filter */
      else if ( mode == FT_PIXEL_MODE_LCD_V && height >= 2 )
      {
        FT_Byte*  column = origin;
  
  
        for ( ; width > 0; width--, column++ )
        {
          FT_Byte*  col = column;
          FT_UInt   fir[5];
          FT_UInt   val, yy;
  
  
          val    = col[0];
          fir[2] = weights[2] * val;
          fir[3] = weights[3] * val;
          fir[4] = weights[4] * val;
          col   -= pitch;
  
          val    = col[0];
          fir[1] = fir[2] + weights[1] * val;
          fir[2] = fir[3] + weights[2] * val;
          fir[3] = fir[4] + weights[3] * val;
          fir[4] =          weights[4] * val;
          col   -= pitch;
  
          for ( yy = 2; yy < height; yy++, col -= pitch )
          {
            val    = col[0];
            fir[0] = fir[1] + weights[0] * val;
            fir[1] = fir[2] + weights[1] * val;
            fir[2] = fir[3] + weights[2] * val;
            fir[3] = fir[4] + weights[3] * val;
            fir[4] =          weights[4] * val;
  
            col[pitch * 2]  = FT_SHIFTCLAMP( fir[0] );
          }
  
          col[pitch * 2]  = FT_SHIFTCLAMP( fir[1] );
          col[pitch]      = FT_SHIFTCLAMP( fir[2] );
        }
      }
    }
  
  
  #ifdef USE_LEGACY
  
    /* intra-pixel filter used by the legacy filter */
    static void
    _ft_lcd_filter_legacy( FT_Bitmap*      bitmap,
                           FT_Byte*        weights )
    {
      FT_UInt   width  = (FT_UInt)bitmap->width;
      FT_UInt   height = (FT_UInt)bitmap->rows;
      FT_Int    pitch  = bitmap->pitch;
      FT_Byte*  origin = bitmap->buffer;
      FT_Byte   mode   = bitmap->pixel_mode;
  
      static const unsigned int  filters[3][3] =
      {
        { 65538 * 9/13, 65538 * 1/6, 65538 * 1/13 },
        { 65538 * 3/13, 65538 * 4/6, 65538 * 3/13 },
        { 65538 * 1/13, 65538 * 1/6, 65538 * 9/13 }
      };
  
      FT_UNUSED( weights );
  
  
      /* take care of bitmap flow */
      if ( pitch > 0 && height > 0 )
        origin += pitch * (FT_Int)( height - 1 );
  
      /* horizontal in-place intra-pixel filter */
      if ( mode == FT_PIXEL_MODE_LCD && width >= 3 )
      {
        FT_Byte*  line = origin;
  
  
        for ( ; height > 0; height--, line -= pitch )
        {
          FT_UInt  xx;
  
  
          for ( xx = 0; xx < width; xx += 3 )
          {
            FT_UInt  r, g, b;
            FT_UInt  p;
  
  
            p  = line[xx];
            r  = filters[0][0] * p;
            g  = filters[0][1] * p;
            b  = filters[0][2] * p;
  
            p  = line[xx + 1];
            r += filters[1][0] * p;
            g += filters[1][1] * p;
            b += filters[1][2] * p;
  
            p  = line[xx + 2];
            r += filters[2][0] * p;
            g += filters[2][1] * p;
            b += filters[2][2] * p;
  
            line[xx]     = (FT_Byte)( r / 65536 );
            line[xx + 1] = (FT_Byte)( g / 65536 );
            line[xx + 2] = (FT_Byte)( b / 65536 );
          }
        }
      }
      else if ( mode == FT_PIXEL_MODE_LCD_V && height >= 3 )
      {
        FT_Byte*  column = origin;
  
  
        for ( ; width > 0; width--, column++ )
        {
          FT_Byte*  col = column - 2 * pitch;
  
  
          for ( ; height > 0; height -= 3, col -= 3 * pitch )
          {
            FT_UInt  r, g, b;
            FT_UInt  p;
  
  
            p  = col[0];
            r  = filters[0][0] * p;
            g  = filters[0][1] * p;
            b  = filters[0][2] * p;
  
            p  = col[pitch];
            r += filters[1][0] * p;
            g += filters[1][1] * p;
            b += filters[1][2] * p;
  
            p  = col[pitch * 2];
            r += filters[2][0] * p;
            g += filters[2][1] * p;
            b += filters[2][2] * p;
  
            col[0]         = (FT_Byte)( r / 65536 );
            col[pitch]     = (FT_Byte)( g / 65536 );
            col[pitch * 2] = (FT_Byte)( b / 65536 );
          }
        }
      }
    }
  
  #endif /* USE_LEGACY */
  
  
    /* documentation in ftlcdfil.h */
  
    FT_EXPORT_DEF( FT_Error )
    FT_Library_SetLcdFilterWeights( FT_Library      library,
                                    unsigned char  *weights )
    {
      if ( !library )
        return FT_THROW( Invalid_Library_Handle );
  
      if ( !weights )
        return FT_THROW( Invalid_Argument );
  
      ft_memcpy( library->lcd_weights, weights, FT_LCD_FILTER_FIVE_TAPS );
      library->lcd_filter_func = ft_lcd_filter_fir;
  
      return FT_Err_Ok;
    }
  
  
    /* documentation in ftlcdfil.h */
  
    FT_EXPORT_DEF( FT_Error )
    FT_Library_SetLcdFilter( FT_Library    library,
                             FT_LcdFilter  filter )
    {
      static const FT_LcdFiveTapFilter  default_weights =
                     { 0x08, 0x4d, 0x56, 0x4d, 0x08 };
      static const FT_LcdFiveTapFilter  light_weights =
                     { 0x00, 0x55, 0x56, 0x55, 0x00 };
  
  
      if ( !library )
        return FT_THROW( Invalid_Library_Handle );
  
      switch ( filter )
      {
      case FT_LCD_FILTER_NONE:
        library->lcd_filter_func = NULL;
        break;
  
      case FT_LCD_FILTER_DEFAULT:
        ft_memcpy( library->lcd_weights,
                   default_weights,
                   FT_LCD_FILTER_FIVE_TAPS );
        library->lcd_filter_func = ft_lcd_filter_fir;
        break;
  
      case FT_LCD_FILTER_LIGHT:
        ft_memcpy( library->lcd_weights,
                   light_weights,
                   FT_LCD_FILTER_FIVE_TAPS );
        library->lcd_filter_func = ft_lcd_filter_fir;
        break;
  
  #ifdef USE_LEGACY
  
      case FT_LCD_FILTER_LEGACY:
      case FT_LCD_FILTER_LEGACY1:
        library->lcd_filter_func = _ft_lcd_filter_legacy;
        break;
  
  #endif
  
      default:
        return FT_THROW( Invalid_Argument );
      }
  
      return FT_Err_Ok;
    }
  
  
    FT_EXPORT_DEF( FT_Error )
    FT_Library_SetLcdGeometry( FT_Library  library,
                               FT_Vector*  sub )
    {
      FT_UNUSED( library );
      FT_UNUSED( sub );
  
      return FT_THROW( Unimplemented_Feature );
    }
  
  #else /* !FT_CONFIG_OPTION_SUBPIXEL_RENDERING */
  
    /* add padding to accommodate outline shifts */
    FT_BASE_DEF( void )
    ft_lcd_padding( FT_BBox*        cbox,
                    FT_GlyphSlot    slot,
                    FT_Render_Mode  mode )
    {
      FT_Vector*  sub = slot->library->lcd_geometry;
  
      if ( mode == FT_RENDER_MODE_LCD )
      {
        cbox->xMin -= FT_MAX( FT_MAX( sub[0].x, sub[1].x ), sub[2].x );
        cbox->xMax -= FT_MIN( FT_MIN( sub[0].x, sub[1].x ), sub[2].x );
        cbox->yMin -= FT_MAX( FT_MAX( sub[0].y, sub[1].y ), sub[2].y );
        cbox->yMax -= FT_MIN( FT_MIN( sub[0].y, sub[1].y ), sub[2].y );
      }
      else if ( mode == FT_RENDER_MODE_LCD_V )
      {
        cbox->xMin -= FT_MAX( FT_MAX( sub[0].y, sub[1].y ), sub[2].y );
        cbox->xMax -= FT_MIN( FT_MIN( sub[0].y, sub[1].y ), sub[2].y );
        cbox->yMin += FT_MIN( FT_MIN( sub[0].x, sub[1].x ), sub[2].x );
        cbox->yMax += FT_MAX( FT_MAX( sub[0].x, sub[1].x ), sub[2].x );
      }
    }
  
  
    FT_EXPORT_DEF( FT_Error )
    FT_Library_SetLcdFilterWeights( FT_Library      library,
                                    unsigned char  *weights )
    {
      FT_UNUSED( library );
      FT_UNUSED( weights );
  
      return FT_THROW( Unimplemented_Feature );
    }
  
  
    FT_EXPORT_DEF( FT_Error )
    FT_Library_SetLcdFilter( FT_Library    library,
                             FT_LcdFilter  filter )
    {
      FT_UNUSED( library );
      FT_UNUSED( filter );
  
      return FT_THROW( Unimplemented_Feature );
    }
  
  
    /* documentation in ftlcdfil.h */
  
    FT_EXPORT_DEF( FT_Error )
    FT_Library_SetLcdGeometry( FT_Library  library,
                               FT_Vector   sub[3] )
    {
      if ( !library )
        return FT_THROW( Invalid_Library_Handle );
  
      if ( !sub )
        return FT_THROW( Invalid_Argument );
  
      ft_memcpy( library->lcd_geometry, sub, 3 * sizeof( FT_Vector ) );
  
      return FT_Err_Ok;
    }
  
  #endif /* !FT_CONFIG_OPTION_SUBPIXEL_RENDERING */
  
  
  /* END */
  

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