ftsmooth.c

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Author : Alexei Podtelezhnikov
Date : 2017-05-20 00:35:21
Hash : ab2599ea
Message : [smooth] Implement minimal dynamic padding for LCD filtering. Extra bitmap padding for LCD filtering depends on the filter. The default 5-tap filter needs 2 extra subpixels. The light 3-tap filter needs only 1 extra subpixel. This space could be already available due to rounding. In order to optimize the padding, we now expand CBox for the given filter weights before rounding. This change breakes current Skia (and Firefox). * include/freetype/internal/ftobjs.h (FT_LibraryRec) [FT_CONFIG_OPTION_SUBPIXEL_RENDERING]: Remove `lcd_extra' field. * src/base/ftlcdfil.c (FT_Library_SetLcdFilterWeights, FT_Library_SetLcdFilter): Remove `lcd_extra' initializations. * src/smooth/ftsmooth.c (ft_smooth_render_generic): Implement dymanic LCD padding.
src/smooth/ftsmooth.c
/***************************************************************************/
/*                                                                         */
/*  ftsmooth.c                                                             */
/*                                                                         */
/*    Anti-aliasing renderer interface (body).                             */
/*                                                                         */
/*  Copyright 2000-2017 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 <ft2build.h>
#include FT_INTERNAL_DEBUG_H
#include FT_INTERNAL_OBJECTS_H
#include FT_OUTLINE_H
#include "ftsmooth.h"
#include "ftgrays.h"
#include "ftspic.h"

#include "ftsmerrs.h"


  /* initialize renderer -- init its raster */
  static FT_Error
  ft_smooth_init( FT_Renderer  render )
  {
    render->clazz->raster_class->raster_reset( render->raster, NULL, 0 );

    return 0;
  }


  /* sets render-specific mode */
  static FT_Error
  ft_smooth_set_mode( FT_Renderer  render,
                      FT_ULong     mode_tag,
                      FT_Pointer   data )
  {
    /* we simply pass it to the raster */
    return render->clazz->raster_class->raster_set_mode( render->raster,
                                                         mode_tag,
                                                         data );
  }

  /* transform a given glyph image */
  static FT_Error
  ft_smooth_transform( FT_Renderer       render,
                       FT_GlyphSlot      slot,
                       const FT_Matrix*  matrix,
                       const FT_Vector*  delta )
  {
    FT_Error  error = FT_Err_Ok;


    if ( slot->format != render->glyph_format )
    {
      error = FT_THROW( Invalid_Argument );
      goto Exit;
    }

    if ( matrix )
      FT_Outline_Transform( &slot->outline, matrix );

    if ( delta )
      FT_Outline_Translate( &slot->outline, delta->x, delta->y );

  Exit:
    return error;
  }


  /* return the glyph's control box */
  static void
  ft_smooth_get_cbox( FT_Renderer   render,
                      FT_GlyphSlot  slot,
                      FT_BBox*      cbox )
  {
    FT_ZERO( cbox );

    if ( slot->format == render->glyph_format )
      FT_Outline_Get_CBox( &slot->outline, cbox );
  }


  /* convert a slot's glyph image into a bitmap */
  static FT_Error
  ft_smooth_render_generic( FT_Renderer       render,
                            FT_GlyphSlot      slot,
                            FT_Render_Mode    mode,
                            const FT_Vector*  origin,
                            FT_Render_Mode    required_mode )
  {
    FT_Error     error;
    FT_Outline*  outline = &slot->outline;
    FT_Bitmap*   bitmap  = &slot->bitmap;
    FT_Memory    memory  = render->root.memory;
    FT_BBox      cbox;
    FT_Pos       x_shift = 0;
    FT_Pos       y_shift = 0;
    FT_Pos       x_left, y_top;
    FT_Pos       width, height, pitch;
#ifndef FT_CONFIG_OPTION_SUBPIXEL_RENDERING
    FT_Pos       height_org, width_org;
#endif
    FT_Int       hmul    = ( mode == FT_RENDER_MODE_LCD );
    FT_Int       vmul    = ( mode == FT_RENDER_MODE_LCD_V );

    FT_Raster_Params  params;

    FT_Bool  have_outline_shifted = FALSE;
    FT_Bool  have_buffer          = FALSE;

#ifdef FT_CONFIG_OPTION_SUBPIXEL_RENDERING

    FT_LcdFiveTapFilter      lcd_weights        = { 0 };
    FT_Bool                  have_custom_weight = FALSE;
    FT_Bitmap_LcdFilterFunc  lcd_filter_func    = NULL;


    if ( slot->face )
    {
      FT_Char  i;


      for ( i = 0; i < FT_LCD_FILTER_FIVE_TAPS; i++ )
        if ( slot->face->internal->lcd_weights[i] != 0 )
        {
          have_custom_weight = TRUE;
          break;
        }
    }

    /*
     * The LCD filter can be set library-wide and per-face.  Face overrides
     * library.  If the face filter weights are all zero (the default), it
     * means that the library default should be used.
     */
    if ( have_custom_weight )
    {
      /*
       * A per-font filter is set.  It always uses the default 5-tap
       * in-place FIR filter.
       */
      ft_memcpy( lcd_weights,
                 slot->face->internal->lcd_weights,
                 FT_LCD_FILTER_FIVE_TAPS );
      lcd_filter_func = ft_lcd_filter_fir;
    }
    else
    {
      /*
       * The face's lcd_weights is {0, 0, 0, 0, 0}, meaning `use library
       * default'.  If the library is set to use no LCD filtering
       * (lcd_filter_func == NULL), `lcd_filter_func' here is also set to
       * NULL and the tests further below pass over the filtering process.
       */
      ft_memcpy( lcd_weights,
                 slot->library->lcd_weights,
                 FT_LCD_FILTER_FIVE_TAPS );
      lcd_filter_func = slot->library->lcd_filter_func;
    }

#endif /*FT_CONFIG_OPTION_SUBPIXEL_RENDERING */

    /* check glyph image format */
    if ( slot->format != render->glyph_format )
    {
      error = FT_THROW( Invalid_Argument );
      goto Exit;
    }

    /* check mode */
    if ( mode != required_mode )
    {
      error = FT_THROW( Cannot_Render_Glyph );
      goto Exit;
    }

    if ( origin )
    {
      x_shift = origin->x;
      y_shift = origin->y;
    }

    /* compute the control box, and grid fit it */
    /* taking into account the origin shift     */
    FT_Outline_Get_CBox( outline, &cbox );

#ifdef FT_CONFIG_OPTION_SUBPIXEL_RENDERING
    /* add minimal padding for LCD filter depending on specific weights */
    if ( lcd_filter_func)
    {
      if ( hmul )
      {
        cbox.xMax += lcd_weights[4] ? 43
                                    : lcd_weights[3] ? 22 : 0;
        cbox.xMin -= lcd_weights[0] ? 43
                                    : lcd_weights[1] ? 22 : 0;
      }

      if ( vmul )
      {
        cbox.yMax += lcd_weights[0] ? 43
                                    : lcd_weights[1] ? 22 : 0;
        cbox.yMin -= lcd_weights[4] ? 43
                                    : lcd_weights[3] ? 22 : 0;
      }
    }
#endif

    cbox.xMin = FT_PIX_FLOOR( cbox.xMin + x_shift );
    cbox.yMin = FT_PIX_FLOOR( cbox.yMin + y_shift );
    cbox.xMax = FT_PIX_CEIL( cbox.xMax + x_shift );
    cbox.yMax = FT_PIX_CEIL( cbox.yMax + y_shift );

    x_shift -= cbox.xMin;
    y_shift -= cbox.yMin;

    x_left  = cbox.xMin >> 6;
    y_top   = cbox.yMax >> 6;

    width  = (FT_ULong)( cbox.xMax - cbox.xMin ) >> 6;
    height = (FT_ULong)( cbox.yMax - cbox.yMin ) >> 6;

#ifndef FT_CONFIG_OPTION_SUBPIXEL_RENDERING
    width_org  = width;
    height_org = height;
#endif

    pitch = width;
    if ( hmul )
    {
      width *= 3;
      pitch  = FT_PAD_CEIL( width, 4 );
    }

    if ( vmul )
      height *= 3;

    /*
     * XXX: on 16bit system, we return an error for huge bitmap
     * to prevent an overflow.
     */
    if ( x_left > FT_INT_MAX || y_top > FT_INT_MAX ||
         x_left < FT_INT_MIN || y_top < FT_INT_MIN )
    {
      error = FT_THROW( Invalid_Pixel_Size );
      goto Exit;
    }

    /* Required check is (pitch * height < FT_ULONG_MAX),        */
    /* but we care realistic cases only.  Always pitch <= width. */
    if ( width > 0x7FFF || height > 0x7FFF )
    {
      FT_ERROR(( "ft_smooth_render_generic: glyph too large: %u x %u\n",
                 width, height ));
      error = FT_THROW( Raster_Overflow );
      goto Exit;
    }

    /* release old bitmap buffer */
    if ( slot->internal->flags & FT_GLYPH_OWN_BITMAP )
    {
      FT_FREE( bitmap->buffer );
      slot->internal->flags &= ~FT_GLYPH_OWN_BITMAP;
    }

    /* allocate new one */
    if ( FT_ALLOC( bitmap->buffer, (FT_ULong)( pitch * height ) ) )
      goto Exit;
    else
      have_buffer = TRUE;

    slot->internal->flags |= FT_GLYPH_OWN_BITMAP;

    slot->format      = FT_GLYPH_FORMAT_BITMAP;
    slot->bitmap_left = (FT_Int)x_left;
    slot->bitmap_top  = (FT_Int)y_top;

    bitmap->pixel_mode = FT_PIXEL_MODE_GRAY;
    bitmap->num_grays  = 256;
    bitmap->width      = (unsigned int)width;
    bitmap->rows       = (unsigned int)height;
    bitmap->pitch      = pitch;

    /* translate outline to render it into the bitmap */
    if ( x_shift || y_shift )
    {
      FT_Outline_Translate( outline, x_shift, y_shift );
      have_outline_shifted = TRUE;
    }

    /* set up parameters */
    params.target = bitmap;
    params.source = outline;
    params.flags  = FT_RASTER_FLAG_AA;

#ifdef FT_CONFIG_OPTION_SUBPIXEL_RENDERING

    /* implode outline if needed */
    {
      FT_Vector*  points     = outline->points;
      FT_Vector*  points_end = points + outline->n_points;
      FT_Vector*  vec;


      if ( hmul )
        for ( vec = points; vec < points_end; vec++ )
          vec->x *= 3;

      if ( vmul )
        for ( vec = points; vec < points_end; vec++ )
          vec->y *= 3;
    }

    /* render outline into the bitmap */
    error = render->raster_render( render->raster, &params );

    /* deflate outline if needed */
    {
      FT_Vector*  points     = outline->points;
      FT_Vector*  points_end = points + outline->n_points;
      FT_Vector*  vec;


      if ( hmul )
        for ( vec = points; vec < points_end; vec++ )
          vec->x /= 3;

      if ( vmul )
        for ( vec = points; vec < points_end; vec++ )
          vec->y /= 3;
    }

    if ( error )
      goto Exit;

    if ( lcd_filter_func )
      lcd_filter_func( bitmap, mode, lcd_weights );

#else /* !FT_CONFIG_OPTION_SUBPIXEL_RENDERING */

    /* render outline into bitmap */
    error = render->raster_render( render->raster, &params );
    if ( error )
      goto Exit;

    /* expand it horizontally */
    if ( hmul )
    {
      FT_Byte*  line = bitmap->buffer;
      FT_UInt   hh;


      for ( hh = height_org; hh > 0; hh--, line += pitch )
      {
        FT_UInt   xx;
        FT_Byte*  end = line + width;


        for ( xx = width_org; xx > 0; xx-- )
        {
          FT_UInt  pixel = line[xx-1];


          end[-3] = (FT_Byte)pixel;
          end[-2] = (FT_Byte)pixel;
          end[-1] = (FT_Byte)pixel;
          end    -= 3;
        }
      }
    }

    /* expand it vertically */
    if ( vmul )
    {
      FT_Byte*  read  = bitmap->buffer + ( height - height_org ) * pitch;
      FT_Byte*  write = bitmap->buffer;
      FT_UInt   hh;


      for ( hh = height_org; hh > 0; hh-- )
      {
        ft_memcpy( write, read, pitch );
        write += pitch;

        ft_memcpy( write, read, pitch );
        write += pitch;

        ft_memcpy( write, read, pitch );
        write += pitch;
        read  += pitch;
      }
    }

#endif /* !FT_CONFIG_OPTION_SUBPIXEL_RENDERING */

    /* everything is fine; don't deallocate buffer */
    have_buffer = FALSE;

    error = FT_Err_Ok;

  Exit:
    if ( have_outline_shifted )
      FT_Outline_Translate( outline, -x_shift, -y_shift );
    if ( have_buffer )
    {
      FT_FREE( bitmap->buffer );
      slot->internal->flags &= ~FT_GLYPH_OWN_BITMAP;
    }

    return error;
  }


  /* convert a slot's glyph image into a bitmap */
  static FT_Error
  ft_smooth_render( FT_Renderer       render,
                    FT_GlyphSlot      slot,
                    FT_Render_Mode    mode,
                    const FT_Vector*  origin )
  {
    if ( mode == FT_RENDER_MODE_LIGHT )
      mode = FT_RENDER_MODE_NORMAL;

    return ft_smooth_render_generic( render, slot, mode, origin,
                                     FT_RENDER_MODE_NORMAL );
  }


  /* convert a slot's glyph image into a horizontal LCD bitmap */
  static FT_Error
  ft_smooth_render_lcd( FT_Renderer       render,
                        FT_GlyphSlot      slot,
                        FT_Render_Mode    mode,
                        const FT_Vector*  origin )
  {
    FT_Error  error;

    error = ft_smooth_render_generic( render, slot, mode, origin,
                                      FT_RENDER_MODE_LCD );
    if ( !error )
      slot->bitmap.pixel_mode = FT_PIXEL_MODE_LCD;

    return error;
  }


  /* convert a slot's glyph image into a vertical LCD bitmap */
  static FT_Error
  ft_smooth_render_lcd_v( FT_Renderer       render,
                          FT_GlyphSlot      slot,
                          FT_Render_Mode    mode,
                          const FT_Vector*  origin )
  {
    FT_Error  error;

    error = ft_smooth_render_generic( render, slot, mode, origin,
                                      FT_RENDER_MODE_LCD_V );
    if ( !error )
      slot->bitmap.pixel_mode = FT_PIXEL_MODE_LCD_V;

    return error;
  }


  FT_DEFINE_RENDERER(
    ft_smooth_renderer_class,

      FT_MODULE_RENDERER,
      sizeof ( FT_RendererRec ),

      "smooth",
      0x10000L,
      0x20000L,

      NULL,    /* module specific interface */

      (FT_Module_Constructor)ft_smooth_init,  /* module_init   */
      (FT_Module_Destructor) NULL,            /* module_done   */
      (FT_Module_Requester)  NULL,            /* get_interface */

    FT_GLYPH_FORMAT_OUTLINE,

    (FT_Renderer_RenderFunc)   ft_smooth_render,     /* render_glyph    */
    (FT_Renderer_TransformFunc)ft_smooth_transform,  /* transform_glyph */
    (FT_Renderer_GetCBoxFunc)  ft_smooth_get_cbox,   /* get_glyph_cbox  */
    (FT_Renderer_SetModeFunc)  ft_smooth_set_mode,   /* set_mode        */

    (FT_Raster_Funcs*)&FT_GRAYS_RASTER_GET           /* raster_class    */
  )


  FT_DEFINE_RENDERER(
    ft_smooth_lcd_renderer_class,

      FT_MODULE_RENDERER,
      sizeof ( FT_RendererRec ),

      "smooth-lcd",
      0x10000L,
      0x20000L,

      NULL,    /* module specific interface */

      (FT_Module_Constructor)ft_smooth_init,  /* module_init   */
      (FT_Module_Destructor) NULL,            /* module_done   */
      (FT_Module_Requester)  NULL,            /* get_interface */

    FT_GLYPH_FORMAT_OUTLINE,

    (FT_Renderer_RenderFunc)   ft_smooth_render_lcd,  /* render_glyph    */
    (FT_Renderer_TransformFunc)ft_smooth_transform,   /* transform_glyph */
    (FT_Renderer_GetCBoxFunc)  ft_smooth_get_cbox,    /* get_glyph_cbox  */
    (FT_Renderer_SetModeFunc)  ft_smooth_set_mode,    /* set_mode        */

    (FT_Raster_Funcs*)&FT_GRAYS_RASTER_GET            /* raster_class    */
  )


  FT_DEFINE_RENDERER(
    ft_smooth_lcdv_renderer_class,

      FT_MODULE_RENDERER,
      sizeof ( FT_RendererRec ),

      "smooth-lcdv",
      0x10000L,
      0x20000L,

      NULL,    /* module specific interface */

      (FT_Module_Constructor)ft_smooth_init,  /* module_init   */
      (FT_Module_Destructor) NULL,            /* module_done   */
      (FT_Module_Requester)  NULL,            /* get_interface */

    FT_GLYPH_FORMAT_OUTLINE,

    (FT_Renderer_RenderFunc)   ft_smooth_render_lcd_v,  /* render_glyph    */
    (FT_Renderer_TransformFunc)ft_smooth_transform,     /* transform_glyph */
    (FT_Renderer_GetCBoxFunc)  ft_smooth_get_cbox,      /* get_glyph_cbox  */
    (FT_Renderer_SetModeFunc)  ft_smooth_set_mode,      /* set_mode        */

    (FT_Raster_Funcs*)&FT_GRAYS_RASTER_GET              /* raster_class    */
  )


/* END */
kc3-lang/freetype/src/smooth/ftsmooth.c

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kc3-lang/freetype /src/smooth/ftsmooth.c
