| /***************************************************************************/ |
| /* */ |
| /* ftlcdfil.c */ |
| /* */ |
| /* FreeType API for color filtering of subpixel bitmap glyphs (body). */ |
| /* */ |
| /* Copyright 2006, 2008-2010, 2013, 2014 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_LCD_FILTER_H |
| #include FT_IMAGE_H |
| #include FT_INTERNAL_OBJECTS_H |
| |
| |
| #ifdef FT_CONFIG_OPTION_SUBPIXEL_RENDERING |
| |
| /* define USE_LEGACY to implement the legacy filter */ |
| #define USE_LEGACY |
| |
| /* 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; |
| |
| |
| /* horizontal in-place FIR filter */ |
| if ( mode == FT_RENDER_MODE_LCD && width >= 4 ) |
| { |
| FT_Byte* line = bitmap->buffer; |
| |
| |
| /* take care of bitmap flow */ |
| if ( bitmap->pitch < 0 ) |
| line -= bitmap->pitch * ( bitmap->rows - 1 ); |
| |
| /* `fir' and `pix' must be at least 32 bit wide, since the sum of */ |
| /* the values in `weights' can exceed 0xFF */ |
| |
| for ( ; height > 0; height--, line += bitmap->pitch ) |
| { |
| FT_UInt fir[4]; /* below, `pix' is used as the 5th element */ |
| FT_UInt val1, xx; |
| |
| |
| val1 = line[0]; |
| fir[0] = weights[2] * val1; |
| fir[1] = weights[3] * val1; |
| fir[2] = weights[4] * val1; |
| fir[3] = 0; |
| |
| val1 = line[1]; |
| fir[0] += weights[1] * val1; |
| fir[1] += weights[2] * val1; |
| fir[2] += weights[3] * val1; |
| fir[3] += weights[4] * val1; |
| |
| for ( xx = 2; xx < width; xx++ ) |
| { |
| FT_UInt val, pix; |
| |
| |
| 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; |
| |
| pix >>= 8; |
| pix |= (FT_UInt)-(FT_Int)( pix >> 8 ); |
| line[xx - 2] = (FT_Byte)pix; |
| } |
| |
| { |
| FT_UInt pix; |
| |
| |
| pix = fir[0] >> 8; |
| pix |= (FT_UInt)-(FT_Int)( pix >> 8 ); |
| line[xx - 2] = (FT_Byte)pix; |
| |
| pix = fir[1] >> 8; |
| pix |= (FT_UInt)-(FT_Int)( pix >> 8 ); |
| line[xx - 1] = (FT_Byte)pix; |
| } |
| } |
| } |
| |
| /* 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; |
| |
| |
| /* take care of bitmap flow */ |
| if ( bitmap->pitch < 0 ) |
| column -= bitmap->pitch * ( bitmap->rows - 1 ); |
| |
| for ( ; width > 0; width--, column++ ) |
| { |
| FT_Byte* col = column; |
| FT_UInt fir[4]; /* below, `pix' is used as the 5th element */ |
| FT_UInt val1, yy; |
| |
| |
| val1 = col[0]; |
| fir[0] = weights[2] * val1; |
| fir[1] = weights[3] * val1; |
| fir[2] = weights[4] * val1; |
| fir[3] = 0; |
| col += pitch; |
| |
| 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; |
| |
| for ( yy = 2; yy < height; yy++ ) |
| { |
| FT_UInt val, pix; |
| |
| |
| 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; |
| |
| pix >>= 8; |
| pix |= (FT_UInt)-(FT_Int)( pix >> 8 ); |
| col[-2 * pitch] = (FT_Byte)pix; |
| col += pitch; |
| } |
| |
| { |
| FT_UInt pix; |
| |
| |
| pix = fir[0] >> 8; |
| pix |= (FT_UInt)-(FT_Int)( pix >> 8 ); |
| col[-2 * pitch] = (FT_Byte)pix; |
| |
| pix = fir[1] >> 8; |
| pix |= (FT_UInt)-(FT_Int)( pix >> 8 ); |
| col[-pitch] = (FT_Byte)pix; |
| } |
| } |
| } |
| } |
| |
| |
| #ifdef USE_LEGACY |
| |
| /* 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; |
| |
| 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 } |
| }; |
| |
| FT_UNUSED( library ); |
| |
| |
| /* horizontal in-place intra-pixel filter */ |
| if ( mode == FT_RENDER_MODE_LCD && width >= 3 ) |
| { |
| FT_Byte* line = bitmap->buffer; |
| |
| |
| /* take care of bitmap flow */ |
| if ( bitmap->pitch < 0 ) |
| line -= bitmap->pitch * ( bitmap->rows - 1 ); |
| |
| for ( ; height > 0; height--, line += pitch ) |
| { |
| FT_UInt xx; |
| |
| |
| for ( xx = 0; xx < width; xx += 3 ) |
| { |
| FT_UInt r = 0; |
| FT_UInt g = 0; |
| FT_UInt b = 0; |
| 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_RENDER_MODE_LCD_V && height >= 3 ) |
| { |
| FT_Byte* column = bitmap->buffer; |
| |
| |
| /* take care of bitmap flow */ |
| if ( bitmap->pitch < 0 ) |
| column -= bitmap->pitch * ( bitmap->rows - 1 ); |
| |
| for ( ; width > 0; width--, column++ ) |
| { |
| FT_Byte* col = column; |
| FT_Byte* col_end = col + height * pitch; |
| |
| |
| for ( ; col < col_end; col += 3 * pitch ) |
| { |
| FT_UInt r = 0; |
| FT_UInt g = 0; |
| FT_UInt b = 0; |
| 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[2 * pitch] = (FT_Byte)( b / 65536 ); |
| } |
| } |
| } |
| } |
| |
| #endif /* USE_LEGACY */ |
| |
| |
| 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, 5 ); |
| |
| return FT_Err_Ok; |
| } |
| |
| |
| 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 }; |
| |
| |
| if ( !library ) |
| return FT_THROW( Invalid_Library_Handle ); |
| |
| switch ( filter ) |
| { |
| case FT_LCD_FILTER_NONE: |
| library->lcd_filter_func = NULL; |
| library->lcd_extra = 0; |
| break; |
| |
| case FT_LCD_FILTER_DEFAULT: |
| #if defined( FT_FORCE_LEGACY_LCD_FILTER ) |
| |
| library->lcd_filter_func = _ft_lcd_filter_legacy; |
| library->lcd_extra = 0; |
| |
| #elif defined( FT_FORCE_LIGHT_LCD_FILTER ) |
| |
| ft_memcpy( library->lcd_weights, light_filter, 5 ); |
| library->lcd_filter_func = _ft_lcd_filter_fir; |
| library->lcd_extra = 2; |
| |
| #else |
| |
| ft_memcpy( library->lcd_weights, default_filter, 5 ); |
| library->lcd_filter_func = _ft_lcd_filter_fir; |
| library->lcd_extra = 2; |
| |
| #endif |
| |
| break; |
| |
| 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; |
| |
| #ifdef USE_LEGACY |
| |
| case FT_LCD_FILTER_LEGACY: |
| library->lcd_filter_func = _ft_lcd_filter_legacy; |
| library->lcd_extra = 0; |
| break; |
| |
| #endif |
| |
| default: |
| return FT_THROW( Invalid_Argument ); |
| } |
| |
| library->lcd_filter = filter; |
| |
| return FT_Err_Ok; |
| } |
| |
| #else /* !FT_CONFIG_OPTION_SUBPIXEL_RENDERING */ |
| |
| 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 ); |
| } |
| |
| #endif /* !FT_CONFIG_OPTION_SUBPIXEL_RENDERING */ |
| |
| |
| /* END */ |
