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/***************************************************************************/ |
/* */ |
/* ftlcdfil.c */ |
/* */ |
/* FreeType API for color filtering of subpixel bitmap glyphs (body). */ |
/* */ |
/* Copyright 2006, 2008-2010, 2013 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. */ |
/* */ |
/***************************************************************************/ |
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#include <ft2build.h> |
#include FT_INTERNAL_DEBUG_H |
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#include FT_LCD_FILTER_H |
#include FT_IMAGE_H |
#include FT_INTERNAL_OBJECTS_H |
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#ifdef FT_CONFIG_OPTION_SUBPIXEL_RENDERING |
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/* define USE_LEGACY to implement the legacy filter */ |
#define USE_LEGACY |
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/* FIR filter used by the default and light filters */ |
static void |
_ft_lcd_filter_fir( FT_Bitmap* bitmap, |
FT_Render_Mode mode, |
FT_Library library ) |
{ |
FT_Byte* weights = library->lcd_weights; |
FT_UInt width = (FT_UInt)bitmap->width; |
FT_UInt height = (FT_UInt)bitmap->rows; |
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/* horizontal in-place FIR filter */ |
if ( mode == FT_RENDER_MODE_LCD && width >= 4 ) |
{ |
FT_Byte* line = bitmap->buffer; |
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for ( ; height > 0; height--, line += bitmap->pitch ) |
{ |
FT_UInt fir[5]; |
FT_UInt val1, xx; |
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val1 = line[0]; |
fir[0] = weights[2] * val1; |
fir[1] = weights[3] * val1; |
fir[2] = weights[4] * val1; |
fir[3] = 0; |
fir[4] = 0; |
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val1 = line[1]; |
fir[0] += weights[1] * val1; |
fir[1] += weights[2] * val1; |
fir[2] += weights[3] * val1; |
fir[3] += weights[4] * val1; |
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for ( xx = 2; xx < width; xx++ ) |
{ |
FT_UInt val, pix; |
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val = line[xx]; |
pix = fir[0] + weights[0] * val; |
fir[0] = fir[1] + weights[1] * val; |
fir[1] = fir[2] + weights[2] * val; |
fir[2] = fir[3] + weights[3] * val; |
fir[3] = weights[4] * val; |
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pix >>= 8; |
pix |= -( pix >> 8 ); |
line[xx - 2] = (FT_Byte)pix; |
} |
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{ |
FT_UInt pix; |
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pix = fir[0] >> 8; |
pix |= -( pix >> 8 ); |
line[xx - 2] = (FT_Byte)pix; |
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pix = fir[1] >> 8; |
pix |= -( pix >> 8 ); |
line[xx - 1] = (FT_Byte)pix; |
} |
} |
} |
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/* vertical in-place FIR filter */ |
else if ( mode == FT_RENDER_MODE_LCD_V && height >= 4 ) |
{ |
FT_Byte* column = bitmap->buffer; |
FT_Int pitch = bitmap->pitch; |
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for ( ; width > 0; width--, column++ ) |
{ |
FT_Byte* col = column; |
FT_UInt fir[5]; |
FT_UInt val1, yy; |
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val1 = col[0]; |
fir[0] = weights[2] * val1; |
fir[1] = weights[3] * val1; |
fir[2] = weights[4] * val1; |
fir[3] = 0; |
fir[4] = 0; |
col += pitch; |
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val1 = col[0]; |
fir[0] += weights[1] * val1; |
fir[1] += weights[2] * val1; |
fir[2] += weights[3] * val1; |
fir[3] += weights[4] * val1; |
col += pitch; |
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for ( yy = 2; yy < height; yy++ ) |
{ |
FT_UInt val, pix; |
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val = col[0]; |
pix = fir[0] + weights[0] * val; |
fir[0] = fir[1] + weights[1] * val; |
fir[1] = fir[2] + weights[2] * val; |
fir[2] = fir[3] + weights[3] * val; |
fir[3] = weights[4] * val; |
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pix >>= 8; |
pix |= -( pix >> 8 ); |
col[-2 * pitch] = (FT_Byte)pix; |
col += pitch; |
} |
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{ |
FT_UInt pix; |
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pix = fir[0] >> 8; |
pix |= -( pix >> 8 ); |
col[-2 * pitch] = (FT_Byte)pix; |
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pix = fir[1] >> 8; |
pix |= -( pix >> 8 ); |
col[-pitch] = (FT_Byte)pix; |
} |
} |
} |
} |
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#ifdef USE_LEGACY |
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/* intra-pixel filter used by the legacy filter */ |
static void |
_ft_lcd_filter_legacy( FT_Bitmap* bitmap, |
FT_Render_Mode mode, |
FT_Library library ) |
{ |
FT_UInt width = (FT_UInt)bitmap->width; |
FT_UInt height = (FT_UInt)bitmap->rows; |
FT_Int pitch = bitmap->pitch; |
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static const 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 } |
}; |
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FT_UNUSED( library ); |
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/* horizontal in-place intra-pixel filter */ |
if ( mode == FT_RENDER_MODE_LCD && width >= 3 ) |
{ |
FT_Byte* line = bitmap->buffer; |
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for ( ; height > 0; height--, line += pitch ) |
{ |
FT_UInt xx; |
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for ( xx = 0; xx < width; xx += 3 ) |
{ |
FT_UInt r = 0; |
FT_UInt g = 0; |
FT_UInt b = 0; |
FT_UInt p; |
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p = line[xx]; |
r += filters[0][0] * p; |
g += filters[0][1] * p; |
b += filters[0][2] * p; |
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p = line[xx + 1]; |
r += filters[1][0] * p; |
g += filters[1][1] * p; |
b += filters[1][2] * p; |
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p = line[xx + 2]; |
r += filters[2][0] * p; |
g += filters[2][1] * p; |
b += filters[2][2] * p; |
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line[xx] = (FT_Byte)( r / 65536 ); |
line[xx + 1] = (FT_Byte)( g / 65536 ); |
line[xx + 2] = (FT_Byte)( b / 65536 ); |
} |
} |
} |
else if ( mode == FT_RENDER_MODE_LCD_V && height >= 3 ) |
{ |
FT_Byte* column = bitmap->buffer; |
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for ( ; width > 0; width--, column++ ) |
{ |
FT_Byte* col = column; |
FT_Byte* col_end = col + height * pitch; |
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for ( ; col < col_end; col += 3 * pitch ) |
{ |
FT_UInt r = 0; |
FT_UInt g = 0; |
FT_UInt b = 0; |
FT_UInt p; |
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p = col[0]; |
r += filters[0][0] * p; |
g += filters[0][1] * p; |
b += filters[0][2] * p; |
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p = col[pitch]; |
r += filters[1][0] * p; |
g += filters[1][1] * p; |
b += filters[1][2] * p; |
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p = col[pitch * 2]; |
r += filters[2][0] * p; |
g += filters[2][1] * p; |
b += filters[2][2] * p; |
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col[0] = (FT_Byte)( r / 65536 ); |
col[pitch] = (FT_Byte)( g / 65536 ); |
col[2 * pitch] = (FT_Byte)( b / 65536 ); |
} |
} |
} |
} |
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#endif /* USE_LEGACY */ |
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FT_EXPORT_DEF( FT_Error ) |
FT_Library_SetLcdFilterWeights( FT_Library library, |
unsigned char *weights ) |
{ |
if ( !library || !weights ) |
return FT_THROW( Invalid_Argument ); |
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ft_memcpy( library->lcd_weights, weights, 5 ); |
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return FT_Err_Ok; |
} |
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FT_EXPORT_DEF( FT_Error ) |
FT_Library_SetLcdFilter( FT_Library library, |
FT_LcdFilter filter ) |
{ |
static const FT_Byte light_filter[5] = |
{ 0x00, 0x55, 0x56, 0x55, 0x00 }; |
/* the values here sum up to a value larger than 256, */ |
/* providing a cheap gamma correction */ |
static const FT_Byte default_filter[5] = |
{ 0x10, 0x40, 0x70, 0x40, 0x10 }; |
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if ( !library ) |
return FT_THROW( Invalid_Argument ); |
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switch ( filter ) |
{ |
case FT_LCD_FILTER_NONE: |
library->lcd_filter_func = NULL; |
library->lcd_extra = 0; |
break; |
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case FT_LCD_FILTER_DEFAULT: |
#if defined( FT_FORCE_LEGACY_LCD_FILTER ) |
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library->lcd_filter_func = _ft_lcd_filter_legacy; |
library->lcd_extra = 0; |
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#elif defined( FT_FORCE_LIGHT_LCD_FILTER ) |
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ft_memcpy( library->lcd_weights, light_filter, 5 ); |
library->lcd_filter_func = _ft_lcd_filter_fir; |
library->lcd_extra = 2; |
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#else |
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ft_memcpy( library->lcd_weights, default_filter, 5 ); |
library->lcd_filter_func = _ft_lcd_filter_fir; |
library->lcd_extra = 2; |
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#endif |
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break; |
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case FT_LCD_FILTER_LIGHT: |
ft_memcpy( library->lcd_weights, light_filter, 5 ); |
library->lcd_filter_func = _ft_lcd_filter_fir; |
library->lcd_extra = 2; |
break; |
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#ifdef USE_LEGACY |
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case FT_LCD_FILTER_LEGACY: |
library->lcd_filter_func = _ft_lcd_filter_legacy; |
library->lcd_extra = 0; |
break; |
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#endif |
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default: |
return FT_THROW( Invalid_Argument ); |
} |
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library->lcd_filter = filter; |
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return FT_Err_Ok; |
} |
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#else /* !FT_CONFIG_OPTION_SUBPIXEL_RENDERING */ |
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FT_EXPORT_DEF( FT_Error ) |
FT_Library_SetLcdFilterWeights( FT_Library library, |
unsigned char *weights ) |
{ |
FT_UNUSED( library ); |
FT_UNUSED( weights ); |
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return FT_THROW( Unimplemented_Feature ); |
} |
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FT_EXPORT_DEF( FT_Error ) |
FT_Library_SetLcdFilter( FT_Library library, |
FT_LcdFilter filter ) |
{ |
FT_UNUSED( library ); |
FT_UNUSED( filter ); |
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return FT_THROW( Unimplemented_Feature ); |
} |
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#endif /* !FT_CONFIG_OPTION_SUBPIXEL_RENDERING */ |
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/* END */ |