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54876
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/****************************************************************************
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*
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* ftlcdfil.c
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*
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* FreeType API for color filtering of subpixel bitmap glyphs (body).
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*
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* Copyright (C) 2006-2019 by
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* David Turner, Robert Wilhelm, and Werner Lemberg.
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*
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* This file is part of the FreeType project, and may only be used,
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* modified, and distributed under the terms of the FreeType project
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* license, LICENSE.TXT. By continuing to use, modify, or distribute
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* this file you indicate that you have read the license and
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* understand and accept it fully.
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*
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*/
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49234
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#include <ft2build.h>
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#include FT_INTERNAL_DEBUG_H
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#include FT_LCD_FILTER_H
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#include FT_IMAGE_H
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#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 */
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#define USE_LEGACY
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#define FT_SHIFTCLAMP( x ) ( x >>= 8, (FT_Byte)( x > 255 ? 255 : x ) )
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/* add padding according to filter weights */
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FT_BASE_DEF (void)
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54876
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ft_lcd_padding( FT_BBox* cbox,
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FT_GlyphSlot slot,
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FT_Render_Mode mode )
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{
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FT_Byte* lcd_weights;
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FT_Bitmap_LcdFilterFunc lcd_filter_func;
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/* Per-face LCD filtering takes priority if set up. */
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if ( slot->face && slot->face->internal->lcd_filter_func )
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{
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lcd_weights = slot->face->internal->lcd_weights;
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lcd_filter_func = slot->face->internal->lcd_filter_func;
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}
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else
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{
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lcd_weights = slot->library->lcd_weights;
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lcd_filter_func = slot->library->lcd_filter_func;
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}
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if ( lcd_filter_func == ft_lcd_filter_fir )
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{
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if ( mode == FT_RENDER_MODE_LCD )
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{
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cbox->xMin -= lcd_weights[0] ? 43 :
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lcd_weights[1] ? 22 : 0;
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cbox->xMax += lcd_weights[4] ? 43 :
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lcd_weights[3] ? 22 : 0;
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}
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else if ( mode == FT_RENDER_MODE_LCD_V )
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{
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cbox->yMin -= lcd_weights[0] ? 43 :
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lcd_weights[1] ? 22 : 0;
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cbox->yMax += lcd_weights[4] ? 43 :
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lcd_weights[3] ? 22 : 0;
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}
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}
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}
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/* FIR filter used by the default and light filters */
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FT_BASE_DEF( void )
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ft_lcd_filter_fir( FT_Bitmap* bitmap,
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FT_Render_Mode mode,
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FT_LcdFiveTapFilter weights )
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{
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FT_UInt width = (FT_UInt)bitmap->width;
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FT_UInt height = (FT_UInt)bitmap->rows;
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FT_Int pitch = bitmap->pitch;
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FT_Byte* origin = bitmap->buffer;
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/* take care of bitmap flow */
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if ( pitch > 0 && height > 0 )
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origin += pitch * (FT_Int)( height - 1 );
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/* horizontal in-place FIR filter */
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if ( mode == FT_RENDER_MODE_LCD && width >= 2 )
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{
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FT_Byte* line = origin;
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/* `fir' must be at least 32 bit wide, since the sum of */
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/* the values in `weights' can exceed 0xFF */
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for ( ; height > 0; height--, line -= pitch )
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{
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FT_UInt fir[5];
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FT_UInt val, xx;
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val = line[0];
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fir[2] = weights[2] * val;
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fir[3] = weights[3] * val;
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fir[4] = weights[4] * val;
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val = line[1];
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fir[1] = fir[2] + weights[1] * val;
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fir[2] = fir[3] + weights[2] * val;
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fir[3] = fir[4] + weights[3] * val;
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fir[4] = weights[4] * val;
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for ( xx = 2; xx < width; xx++ )
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{
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val = line[xx];
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fir[0] = fir[1] + weights[0] * val;
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fir[1] = fir[2] + weights[1] * val;
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fir[2] = fir[3] + weights[2] * val;
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fir[3] = fir[4] + weights[3] * val;
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fir[4] = weights[4] * val;
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line[xx - 2] = FT_SHIFTCLAMP( fir[0] );
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}
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line[xx - 2] = FT_SHIFTCLAMP( fir[1] );
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line[xx - 1] = FT_SHIFTCLAMP( fir[2] );
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}
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}
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/* vertical in-place FIR filter */
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else if ( mode == FT_RENDER_MODE_LCD_V && height >= 2 )
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{
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FT_Byte* column = origin;
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for ( ; width > 0; width--, column++ )
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{
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FT_Byte* col = column;
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FT_UInt fir[5];
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FT_UInt val, yy;
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val = col[0];
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fir[2] = weights[2] * val;
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fir[3] = weights[3] * val;
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fir[4] = weights[4] * val;
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col -= pitch;
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val = col[0];
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fir[1] = fir[2] + weights[1] * val;
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fir[2] = fir[3] + weights[2] * val;
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fir[3] = fir[4] + weights[3] * val;
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fir[4] = weights[4] * val;
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col -= pitch;
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for ( yy = 2; yy < height; yy++, col -= pitch )
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{
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val = col[0];
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fir[0] = fir[1] + weights[0] * val;
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fir[1] = fir[2] + weights[1] * val;
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fir[2] = fir[3] + weights[2] * val;
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fir[3] = fir[4] + weights[3] * val;
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fir[4] = weights[4] * val;
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col[pitch * 2] = FT_SHIFTCLAMP( fir[0] );
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}
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col[pitch * 2] = FT_SHIFTCLAMP( fir[1] );
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col[pitch] = FT_SHIFTCLAMP( fir[2] );
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}
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}
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}
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#ifdef USE_LEGACY
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/* intra-pixel filter used by the legacy filter */
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static void
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_ft_lcd_filter_legacy( FT_Bitmap* bitmap,
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FT_Render_Mode mode,
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FT_Byte* weights )
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{
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FT_UInt width = (FT_UInt)bitmap->width;
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FT_UInt height = (FT_UInt)bitmap->rows;
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FT_Int pitch = bitmap->pitch;
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FT_Byte* origin = bitmap->buffer;
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static const unsigned int filters[3][3] =
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{
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{ 65538 * 9/13, 65538 * 1/6, 65538 * 1/13 },
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{ 65538 * 3/13, 65538 * 4/6, 65538 * 3/13 },
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{ 65538 * 1/13, 65538 * 1/6, 65538 * 9/13 }
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};
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FT_UNUSED( weights );
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/* take care of bitmap flow */
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if ( pitch > 0 && height > 0 )
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origin += pitch * (FT_Int)( height - 1 );
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/* horizontal in-place intra-pixel filter */
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if ( mode == FT_RENDER_MODE_LCD && width >= 3 )
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{
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FT_Byte* line = origin;
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for ( ; height > 0; height--, line -= pitch )
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{
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FT_UInt xx;
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for ( xx = 0; xx < width; xx += 3 )
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{
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FT_UInt r, g, b;
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FT_UInt p;
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p = line[xx];
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r = filters[0][0] * p;
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g = filters[0][1] * p;
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b = filters[0][2] * p;
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p = line[xx + 1];
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r += filters[1][0] * p;
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g += filters[1][1] * p;
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b += filters[1][2] * p;
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p = line[xx + 2];
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r += filters[2][0] * p;
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g += filters[2][1] * p;
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b += filters[2][2] * p;
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line[xx] = (FT_Byte)( r / 65536 );
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line[xx + 1] = (FT_Byte)( g / 65536 );
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line[xx + 2] = (FT_Byte)( b / 65536 );
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}
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}
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}
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else if ( mode == FT_RENDER_MODE_LCD_V && height >= 3 )
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{
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FT_Byte* column = origin;
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for ( ; width > 0; width--, column++ )
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{
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FT_Byte* col = column - 2 * pitch;
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for ( ; height > 0; height -= 3, col -= 3 * pitch )
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{
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FT_UInt r, g, b;
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FT_UInt p;
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p = col[0];
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r = filters[0][0] * p;
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g = filters[0][1] * p;
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b = filters[0][2] * p;
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p = col[pitch];
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r += filters[1][0] * p;
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g += filters[1][1] * p;
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b += filters[1][2] * p;
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p = col[pitch * 2];
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r += filters[2][0] * p;
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g += filters[2][1] * p;
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b += filters[2][2] * p;
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col[0] = (FT_Byte)( r / 65536 );
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col[pitch] = (FT_Byte)( g / 65536 );
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col[pitch * 2] = (FT_Byte)( b / 65536 );
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}
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}
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}
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}
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#endif /* USE_LEGACY */
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54876
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/* documentation in ftlcdfil.h */
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49234
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FT_EXPORT_DEF( FT_Error )
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FT_Library_SetLcdFilterWeights( FT_Library library,
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unsigned char *weights )
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{
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if ( !library )
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return FT_THROW( Invalid_Library_Handle );
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if ( !weights )
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return FT_THROW( Invalid_Argument );
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ft_memcpy( library->lcd_weights, weights, FT_LCD_FILTER_FIVE_TAPS );
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library->lcd_filter_func = ft_lcd_filter_fir;
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return FT_Err_Ok;
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}
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54876
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/* documentation in ftlcdfil.h */
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308 |
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49234
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FT_EXPORT_DEF( FT_Error )
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FT_Library_SetLcdFilter( FT_Library library,
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FT_LcdFilter filter )
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{
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static const FT_LcdFiveTapFilter default_weights =
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{ 0x08, 0x4d, 0x56, 0x4d, 0x08 };
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static const FT_LcdFiveTapFilter light_weights =
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{ 0x00, 0x55, 0x56, 0x55, 0x00 };
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if ( !library )
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return FT_THROW( Invalid_Library_Handle );
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switch ( filter )
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{
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case FT_LCD_FILTER_NONE:
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library->lcd_filter_func = NULL;
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break;
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case FT_LCD_FILTER_DEFAULT:
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ft_memcpy( library->lcd_weights,
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default_weights,
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FT_LCD_FILTER_FIVE_TAPS );
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library->lcd_filter_func = ft_lcd_filter_fir;
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break;
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case FT_LCD_FILTER_LIGHT:
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ft_memcpy( library->lcd_weights,
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light_weights,
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FT_LCD_FILTER_FIVE_TAPS );
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library->lcd_filter_func = ft_lcd_filter_fir;
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break;
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#ifdef USE_LEGACY
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343 |
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case FT_LCD_FILTER_LEGACY:
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case FT_LCD_FILTER_LEGACY1:
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library->lcd_filter_func = _ft_lcd_filter_legacy;
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break;
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#endif
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350 |
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default:
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return FT_THROW( Invalid_Argument );
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}
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354 |
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return FT_Err_Ok;
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}
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54876
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359 |
FT_EXPORT_DEF( FT_Error )
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360 |
FT_Library_SetLcdGeometry( FT_Library library,
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361 |
FT_Vector* sub )
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362 |
{
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363 |
FT_UNUSED( library );
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364 |
FT_UNUSED( sub );
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365 |
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return FT_THROW( Unimplemented_Feature );
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367 |
}
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368 |
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49234
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369 |
#else /* !FT_CONFIG_OPTION_SUBPIXEL_RENDERING */
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370 |
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/* add padding to accommodate outline shifts */
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FT_BASE_DEF (void)
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ft_lcd_padding( FT_BBox* cbox,
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FT_GlyphSlot slot,
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FT_Render_Mode mode )
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{
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FT_Vector* sub = slot->library->lcd_geometry;
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if ( mode == FT_RENDER_MODE_LCD )
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{
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cbox->xMin -= FT_MAX( FT_MAX( sub[0].x, sub[1].x ), sub[2].x );
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cbox->xMax -= FT_MIN( FT_MIN( sub[0].x, sub[1].x ), sub[2].x );
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cbox->yMin -= FT_MAX( FT_MAX( sub[0].y, sub[1].y ), sub[2].y );
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cbox->yMax -= FT_MIN( FT_MIN( sub[0].y, sub[1].y ), sub[2].y );
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}
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else if ( mode == FT_RENDER_MODE_LCD_V )
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{
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cbox->xMin -= FT_MAX( FT_MAX( sub[0].y, sub[1].y ), sub[2].y );
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cbox->xMax -= FT_MIN( FT_MIN( sub[0].y, sub[1].y ), sub[2].y );
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cbox->yMin += FT_MIN( FT_MIN( sub[0].x, sub[1].x ), sub[2].x );
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cbox->yMax += FT_MAX( FT_MAX( sub[0].x, sub[1].x ), sub[2].x );
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}
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}
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394 |
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395 |
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FT_EXPORT_DEF( FT_Error )
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397 |
FT_Library_SetLcdFilterWeights( FT_Library library,
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398 |
unsigned char *weights )
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399 |
{
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400 |
FT_UNUSED( library );
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FT_UNUSED( weights );
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402 |
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403 |
return FT_THROW( Unimplemented_Feature );
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}
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405 |
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406 |
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407 |
FT_EXPORT_DEF( FT_Error )
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FT_Library_SetLcdFilter( FT_Library library,
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409 |
FT_LcdFilter filter )
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{
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411 |
FT_UNUSED( library );
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412 |
FT_UNUSED( filter );
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413 |
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414 |
return FT_THROW( Unimplemented_Feature );
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}
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416 |
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417 |
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418 |
/* documentation in ftlcdfil.h */
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419 |
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420 |
FT_EXPORT_DEF( FT_Error )
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421 |
FT_Library_SetLcdGeometry( FT_Library library,
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422 |
FT_Vector sub[3] )
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423 |
{
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424 |
if ( !library )
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425 |
return FT_THROW( Invalid_Library_Handle );
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426 |
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427 |
if ( !sub )
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428 |
return FT_THROW( Invalid_Argument );
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429 |
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430 |
ft_memcpy( library->lcd_geometry, sub, 3 * sizeof( FT_Vector ) );
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431 |
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432 |
return FT_THROW( Unimplemented_Feature );
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433 |
}
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434 |
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435 |
#endif /* !FT_CONFIG_OPTION_SUBPIXEL_RENDERING */
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436 |
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437 |
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|
438 |
/* END */
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