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Add new `slight' auto-hinting mode. 

This mode uses fractional advance widths and doesn't scale glyphs
horizontally, only applying vertical scaling and hinting.

At the same time, the behaviour of the `light' auto-hinter gets
restored for backwards compatibility: Both vertical and horizontal
scaling is again based on rounded metrics values (this was changed
in a commit from 2017-03-30 as a side effect).  To be more precise,
the behaviour is restored for TrueType fonts only; for other font
formats like Type 1, this is a new feature of the `light' hinting
mode.

* include/freetype/freetype.h (FT_LOAD_TARGET_SLIGHT): New macro.
(FT_RENDER_MODE_SLIGHT): New render mode.

* include/freetype/internal/ftobjs.h (FT_Size_InternalRec): Add
`autohint_mode' and `autohint_metrics' fields.

* src/autofit/afcjk.c (af_cjk_hints_init), src/autofit/aflatin.c
(af_latin_hints_init), src/autofit/aflatin2 (af_latin2_hints_init):
Updated.

* src/autofit/afloader.c (af_loader_embolden_glyph_in_slot): Use
`autohint_metrics'.
(af_loader_load_glyph): s/internal/slot_internal/.
Initialize `autohint_metrics' and `autohint_mode' depending on
current auto-hint mode.
Use `autohint_metrics'.
Updated.

* src/base/ftadvanc.c (LOAD_ADVANCE_FAST_CHECK): Updated.

* src/base/ftobjs.c (FT_Load_Glyph): Updated.
(FT_New_Size): Allocate `internal' object.

* src/pshinter/pshalgo.c (ps_hints_apply): Updated.

* src/smooth/ftsmooth.c (ft_smooth_render): Updated.
This commit is contained in:
Werner Lemberg 2017-04-22 13:27:21 +02:00
parent 69da54cacc
commit 5aa6716a5e
11 changed files with 187 additions and 41 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

42
ChangeLog
View File

@ -1,3 +1,45 @@
2017-04-22 Werner Lemberg <wl@gnu.org>
Add new `slight' auto-hinting mode.
This mode uses fractional advance widths and doesn't scale glyphs
horizontally, only applying vertical scaling and hinting.
At the same time, the behaviour of the `light' auto-hinter gets
restored for backwards compatibility: Both vertical and horizontal
scaling is again based on rounded metrics values (this was changed
in a commit from 2017-03-30 as a side effect). To be more precise,
the behaviour is restored for TrueType fonts only; for other font
formats like Type 1, this is a new feature of the `light' hinting
mode.
* include/freetype/freetype.h (FT_LOAD_TARGET_SLIGHT): New macro.
(FT_RENDER_MODE_SLIGHT): New render mode.
* include/freetype/internal/ftobjs.h (FT_Size_InternalRec): Add
`autohint_mode' and `autohint_metrics' fields.
* src/autofit/afcjk.c (af_cjk_hints_init), src/autofit/aflatin.c
(af_latin_hints_init), src/autofit/aflatin2 (af_latin2_hints_init):
Updated.
* src/autofit/afloader.c (af_loader_embolden_glyph_in_slot): Use
`autohint_metrics'.
(af_loader_load_glyph): s/internal/slot_internal/.
Initialize `autohint_metrics' and `autohint_mode' depending on
current auto-hint mode.
Use `autohint_metrics'.
Updated.
* src/base/ftadvanc.c (LOAD_ADVANCE_FAST_CHECK): Updated.
* src/base/ftobjs.c (FT_Load_Glyph): Updated.
(FT_New_Size): Allocate `internal' object.
* src/pshinter/pshalgo.c (ps_hints_apply): Updated.
* src/smooth/ftsmooth.c (ft_smooth_render): Updated.
2017-04-22 Werner Lemberg <wl@gnu.org>
Introduce `FT_Size_InternalRec' structure.

31
include/freetype/freetype.h
View File

@ -221,6 +221,7 @@ FT_BEGIN_HEADER
/* */
/* FT_LOAD_TARGET_NORMAL */
/* FT_LOAD_TARGET_LIGHT */
/* FT_LOAD_TARGET_SLIGHT */
/* FT_LOAD_TARGET_MONO */
/* FT_LOAD_TARGET_LCD */
/* FT_LOAD_TARGET_LCD_V */
@ -1755,7 +1756,8 @@ FT_BEGIN_HEADER
/* `slot->format' is also changed to @FT_GLYPH_FORMAT_BITMAP. */
/* */
/* Here is a small pseudo code fragment that shows how to use */
/* `lsb_delta' and `rsb_delta': */
/* `lsb_delta' and `rsb_delta' to improve (integer) positioning of */
/* glyphs: */
/* */
/* { */
/* FT_Pos origin_x = 0; */
@ -2941,6 +2943,18 @@ FT_BEGIN_HEADER
* driver, if the driver itself and the font support it, or by the
* auto-hinter.
*
* Use this hinting mode if you mainly need integer advance widths
* and want to avoid sub-pixel rendering.
*
* FT_LOAD_TARGET_SLIGHT ::
* This is similar to @FT_LOAD_TARGET_LIGHT with a main difference:
* Advance widths are not rounded to integer values; instead, the
* linearly scaled values are used. In particular this implies that
* you have to apply sub-pixel rendering.
*
* In general, this mode yields better results than
* @FT_LOAD_TARGET_LIGHT.
*
* FT_LOAD_TARGET_MONO ::
* Strong hinting algorithm that should only be used for monochrome
* output. The result is probably unpleasant if the glyph is rendered
@ -2975,11 +2989,19 @@ FT_BEGIN_HEADER
* FT_Render_Glyph( face->glyph, FT_RENDER_MODE_LCD );
* }
*
* In general, you should stick with one rendering mode. For example,
* switching between @FT_LOAD_TARGET_LIGHT and @FT_LOAD_TARGET_SLIGHT
* enforces a lot of recomputation, which is slow. Another reason is
* caching: Selecting a different mode usually causes changes in both
* the outlines and the rasterized bitmaps; it is thus necessary to
* empty the cache after a mode switch to avoid false hits.
*
*/
#define FT_LOAD_TARGET_( x ) ( (FT_Int32)( (x) & 15 ) << 16 )
#define FT_LOAD_TARGET_NORMAL FT_LOAD_TARGET_( FT_RENDER_MODE_NORMAL )
#define FT_LOAD_TARGET_LIGHT FT_LOAD_TARGET_( FT_RENDER_MODE_LIGHT )
#define FT_LOAD_TARGET_SLIGHT FT_LOAD_TARGET_( FT_RENDER_MODE_SLIGHT )
#define FT_LOAD_TARGET_MONO FT_LOAD_TARGET_( FT_RENDER_MODE_MONO )
#define FT_LOAD_TARGET_LCD FT_LOAD_TARGET_( FT_RENDER_MODE_LCD )
#define FT_LOAD_TARGET_LCD_V FT_LOAD_TARGET_( FT_RENDER_MODE_LCD_V )
@ -3060,6 +3082,12 @@ FT_BEGIN_HEADER
/* indirectly to define hinting algorithm selectors. See */
/* @FT_LOAD_TARGET_XXX for details. */
/* */
/* FT_RENDER_MODE_SLIGHT :: */
/* This is equivalent to @FT_RENDER_MODE_NORMAL. It is only */
/* defined as a separate value because render modes are also used */
/* indirectly to define hinting algorithm selectors. See */
/* @FT_LOAD_TARGET_XXX for details. */
/* */
/* FT_RENDER_MODE_MONO :: */
/* This mode corresponds to 1-bit bitmaps (with 2~levels of */
/* opacity). */
@ -3092,6 +3120,7 @@ FT_BEGIN_HEADER
{
FT_RENDER_MODE_NORMAL = 0,
FT_RENDER_MODE_LIGHT,
FT_RENDER_MODE_SLIGHT,
FT_RENDER_MODE_MONO,
FT_RENDER_MODE_LCD,
FT_RENDER_MODE_LCD_V,

9
include/freetype/internal/ftobjs.h
View File

@ -443,7 +443,11 @@ FT_BEGIN_HEADER
/* object. */
/* */
/* <Fields> */
/* module_data :: Data specific to a driver module. */
/* module_data :: Data specific to a driver module. */
/* */
/* autohint_mode :: The used auto-hinting mode. */
/* */
/* autohint_metrics :: Metrics used by the auto-hinter. */
/* */
/*************************************************************************/
@ -451,6 +455,9 @@ FT_BEGIN_HEADER
{
void* module_data;
FT_Render_Mode autohint_mode;
FT_Size_Metrics autohint_metrics;
} FT_Size_InternalRec;

7
src/autofit/afcjk.c
View File

@ -1398,9 +1398,12 @@
other_flags |= AF_LATIN_HINTS_VERT_SNAP;
/*
* We adjust stems to full pixels unless in `light' or `lcd' mode.
* We adjust stems to full pixels unless in `light', `slight',
* or `lcd' mode.
*/
if ( mode != FT_RENDER_MODE_LIGHT && mode != FT_RENDER_MODE_LCD )
if ( mode != FT_RENDER_MODE_LIGHT &&
mode != FT_RENDER_MODE_SLIGHT &&
mode != FT_RENDER_MODE_LCD )
other_flags |= AF_LATIN_HINTS_STEM_ADJUST;
if ( mode == FT_RENDER_MODE_MONO )

10
src/autofit/aflatin.c
View File

@ -2577,7 +2577,9 @@
/*
* We adjust stems to full pixels unless in `light' or `lcd' mode.
*/
if ( mode != FT_RENDER_MODE_LIGHT && mode != FT_RENDER_MODE_LCD )
if ( mode != FT_RENDER_MODE_LIGHT &&
mode != FT_RENDER_MODE_SLIGHT &&
mode != FT_RENDER_MODE_LCD )
other_flags |= AF_LATIN_HINTS_STEM_ADJUST;
if ( mode == FT_RENDER_MODE_MONO )
@ -2590,8 +2592,10 @@
* However, if warping is enabled (which only works in `light' hinting
* mode), advance widths get adjusted, too.
*/
if ( mode == FT_RENDER_MODE_LIGHT || mode == FT_RENDER_MODE_LCD ||
( face->style_flags & FT_STYLE_FLAG_ITALIC ) != 0 )
if ( mode == FT_RENDER_MODE_LIGHT ||
mode == FT_RENDER_MODE_SLIGHT ||
mode == FT_RENDER_MODE_LCD ||
( face->style_flags & FT_STYLE_FLAG_ITALIC ) != 0 )
scaler_flags |= AF_SCALER_FLAG_NO_HORIZONTAL;
#ifdef AF_CONFIG_OPTION_USE_WARPER

10
src/autofit/aflatin2.c
View File

@ -1560,7 +1560,9 @@
/*
* We adjust stems to full pixels unless in `light' or `lcd' mode.
*/
if ( mode != FT_RENDER_MODE_LIGHT && mode != FT_RENDER_MODE_LCD )
if ( mode != FT_RENDER_MODE_LIGHT &&
mode != FT_RENDER_MODE_SLIGHT &&
mode != FT_RENDER_MODE_LCD )
other_flags |= AF_LATIN_HINTS_STEM_ADJUST;
if ( mode == FT_RENDER_MODE_MONO )
@ -1570,8 +1572,10 @@
* In `light' or `lcd' mode we disable horizontal hinting completely.
* We also do it if the face is italic.
*/
if ( mode == FT_RENDER_MODE_LIGHT || mode == FT_RENDER_MODE_LCD ||
( face->style_flags & FT_STYLE_FLAG_ITALIC ) != 0 )
if ( mode == FT_RENDER_MODE_LIGHT ||
mode == FT_RENDER_MODE_SLIGHT ||
mode == FT_RENDER_MODE_LCD ||
( face->style_flags & FT_STYLE_FLAG_ITALIC ) != 0 )
scaler_flags |= AF_SCALER_FLAG_NO_HORIZONTAL;
#ifdef AF_CONFIG_OPTION_USE_WARPER

95
src/autofit/afloader.c
View File

@ -97,11 +97,13 @@
AF_FaceGlobals globals = loader->globals;
AF_WritingSystemClass writing_system_class;
FT_Size_Metrics* size_metrics = &face->size->internal->autohint_metrics;
FT_Pos stdVW = 0;
FT_Pos stdHW = 0;
FT_Bool size_changed = face->size->metrics.x_ppem
!= globals->stem_darkening_for_ppem;
FT_Bool size_changed = size_metrics->x_ppem !=
globals->stem_darkening_for_ppem;
FT_Fixed em_size = af_intToFixed( face->units_per_EM );
FT_Fixed em_ratio = FT_DivFix( af_intToFixed( 1000 ), em_size );
@ -145,11 +147,11 @@
face,
stdVW ) );
darken_x = FT_DivFix( FT_MulFix( darken_by_font_units_x,
face->size->metrics.x_scale ),
size_metrics->x_scale ),
em_ratio );
globals->standard_vertical_width = stdVW;
globals->stem_darkening_for_ppem = face->size->metrics.x_ppem;
globals->stem_darkening_for_ppem = size_metrics->x_ppem;
globals->darken_x = af_fixedToInt( darken_x );
}
@ -164,11 +166,11 @@
face,
stdHW ) );
darken_y = FT_DivFix( FT_MulFix( darken_by_font_units_y,
face->size->metrics.y_scale ),
size_metrics->y_scale ),
em_ratio );
globals->standard_horizontal_width = stdHW;
globals->stem_darkening_for_ppem = face->size->metrics.x_ppem;
globals->stem_darkening_for_ppem = size_metrics->x_ppem;
globals->darken_y = af_fixedToInt( darken_y );
/*
@ -217,10 +219,11 @@
{
FT_Error error;
FT_Size size = face->size;
FT_GlyphSlot slot = face->glyph;
FT_Slot_Internal internal = slot->internal;
FT_GlyphLoader gloader = internal->loader;
FT_Size size = face->size;
FT_Size_Internal size_internal = size->internal;
FT_GlyphSlot slot = face->glyph;
FT_Slot_Internal slot_internal = slot->internal;
FT_GlyphLoader gloader = slot_internal->loader;
AF_GlyphHints hints = loader->hints;
AF_ScalerRec scaler;
@ -239,6 +242,44 @@
FT_ZERO( &scaler );
if ( !size_internal->autohint_metrics.x_scale ||
size_internal->autohint_mode != FT_LOAD_TARGET_MODE( load_flags ) )
{
/* switching between LIGHT and SLIGHT (and vice versa) usually means */
/* different scaling values; this later on enforces recomputation of */
/* everything related to the current size */
size_internal->autohint_mode = FT_LOAD_TARGET_MODE( load_flags );
size_internal->autohint_metrics = size->metrics;
if ( size_internal->autohint_mode != FT_RENDER_MODE_SLIGHT )
{
FT_Size_Metrics* size_metrics = &size_internal->autohint_metrics;
/* set metrics to integer values and adjust scaling accordingly; */
/* this is the same setup as with TrueType fonts, cf. function */
/* `tt_size_reset' in file `ttobjs.c' */
size_metrics->ascender = FT_PIX_ROUND(
FT_MulFix( face->ascender,
size_metrics->y_scale ) );
size_metrics->descender = FT_PIX_ROUND(
FT_MulFix( face->descender,
size_metrics->y_scale ) );
size_metrics->height = FT_PIX_ROUND(
FT_MulFix( face->height,
size_metrics->y_scale ) );
size_metrics->x_scale = FT_DivFix( size_metrics->x_ppem << 6,
face->units_per_EM );
size_metrics->y_scale = FT_DivFix( size_metrics->y_ppem << 6,
face->units_per_EM );
size_metrics->max_advance = FT_PIX_ROUND(
FT_MulFix( face->max_advance_width,
size_metrics->x_scale ) );
}
}
/*
* TODO: This code currently doesn't support fractional advance widths,
* i.e., placing hinted glyphs at anything other than integer
@ -249,9 +290,9 @@
* values of the scaler would need to be adjusted.
*/
scaler.face = face;
scaler.x_scale = size->metrics.x_scale;
scaler.x_scale = size_internal->autohint_metrics.x_scale;
scaler.x_delta = 0;
scaler.y_scale = size->metrics.y_scale;
scaler.y_scale = size_internal->autohint_metrics.y_scale;
scaler.y_delta = 0;
scaler.render_mode = FT_LOAD_TARGET_MODE( load_flags );
@ -339,21 +380,22 @@
*
*/
/* stem darkening only works well in `light' mode */
if ( scaler.render_mode == FT_RENDER_MODE_LIGHT &&
/* stem darkening only works well in `light' and `slight' modes */
if ( ( scaler.render_mode == FT_RENDER_MODE_LIGHT ||
scaler.render_mode == FT_RENDER_MODE_SLIGHT ) &&
( !face->internal->no_stem_darkening ||
( face->internal->no_stem_darkening < 0 &&
!module->no_stem_darkening ) ) )
!module->no_stem_darkening ) ) )
af_loader_embolden_glyph_in_slot( loader, face, style_metrics );
loader->transformed = internal->glyph_transformed;
loader->transformed = slot_internal->glyph_transformed;
if ( loader->transformed )
{
FT_Matrix inverse;
loader->trans_matrix = internal->glyph_matrix;
loader->trans_delta = internal->glyph_delta;
loader->trans_matrix = slot_internal->glyph_matrix;
loader->trans_delta = slot_internal->glyph_delta;
inverse = loader->trans_matrix;
if ( !FT_Matrix_Invert( &inverse ) )
@ -391,7 +433,8 @@
/* we now need to adjust the metrics according to the change in */
/* width/positioning that occurred during the hinting process */
if ( scaler.render_mode != FT_RENDER_MODE_LIGHT )
if ( scaler.render_mode != FT_RENDER_MODE_LIGHT &&
scaler.render_mode != FT_RENDER_MODE_SLIGHT )
{
FT_Pos old_rsb, old_lsb, new_lsb;
FT_Pos pp1x_uh, pp2x_uh;
@ -448,7 +491,10 @@
slot->rsb_delta = loader->pp2.x - pp2x;
}
}
else
/* `light' mode uses integer advance widths */
/* (but sets `lsb_delta' and `rsb_delta'), */
/* `slight' mode uses fractional values */
else if ( scaler.render_mode == FT_RENDER_MODE_LIGHT )
{
FT_Pos pp1x = loader->pp1.x;
FT_Pos pp2x = loader->pp2.x;
@ -460,6 +506,11 @@
slot->lsb_delta = loader->pp1.x - pp1x;
slot->rsb_delta = loader->pp2.x - pp2x;
}
else
{
slot->lsb_delta = 0;
slot->rsb_delta = 0;
}
break;
@ -510,6 +561,7 @@
/* to keep the original rounded advance width; ditto for */
/* digits if all have the same advance width */
if ( scaler.render_mode != FT_RENDER_MODE_LIGHT &&
scaler.render_mode != FT_RENDER_MODE_SLIGHT &&
( FT_IS_FIXED_WIDTH( slot->face ) ||
( af_face_globals_is_digit( loader->globals, glyph_index ) &&
style_metrics->digits_have_same_width ) ) )
@ -533,7 +585,8 @@
slot->metrics.vertAdvance = FT_MulFix( slot->metrics.vertAdvance,
style_metrics->scaler.y_scale );
slot->metrics.horiAdvance = FT_PIX_ROUND( slot->metrics.horiAdvance );
if ( scaler.render_mode != FT_RENDER_MODE_SLIGHT )
slot->metrics.horiAdvance = FT_PIX_ROUND( slot->metrics.horiAdvance );
slot->metrics.vertAdvance = FT_PIX_ROUND( slot->metrics.vertAdvance );
slot->format = FT_GLYPH_FORMAT_OUTLINE;

9
src/base/ftadvanc.c
View File

@ -59,14 +59,15 @@
/* */
/* - unscaled load */
/* - unhinted load */
/* - light-hinted load */
/* - light-hinted and slight-hinted load */
/* - if a variations font, it must have an `HVAR' or `VVAR' */
/* table (thus the old MM or GX fonts don't qualify; this */
/* gets checked by the driver-specific functions) */
#define LOAD_ADVANCE_FAST_CHECK( face, flags ) \
( flags & ( FT_LOAD_NO_SCALE | FT_LOAD_NO_HINTING ) || \
FT_LOAD_TARGET_MODE( flags ) == FT_RENDER_MODE_LIGHT )
#define LOAD_ADVANCE_FAST_CHECK( face, flags ) \
( flags & ( FT_LOAD_NO_SCALE | FT_LOAD_NO_HINTING ) || \
( FT_LOAD_TARGET_MODE( flags ) == FT_RENDER_MODE_LIGHT || \
FT_LOAD_TARGET_MODE( flags ) == FT_RENDER_MODE_SLIGHT ) )
/* documentation is in ftadvanc.h */

9
src/base/ftobjs.c
View File

@ -668,8 +668,8 @@
* - Then, auto-hint if FT_LOAD_FORCE_AUTOHINT is set or if we don't
* have a native font hinter.
*
* - Otherwise, auto-hint for LIGHT hinting mode or if there isn't
* any hinting bytecode in the TrueType/OpenType font.
* - Otherwise, auto-hint for LIGHT or SLIGHT hinting mode or if there
* isn't any hinting bytecode in the TrueType/OpenType font.
*
* - Exception: The font is `tricky' and requires the native hinter to
* load properly.
@ -702,8 +702,9 @@
/* check the size of the `fpgm' and `prep' tables, too -- */
/* the assumption is that there don't exist real TTFs where */
/* both `fpgm' and `prep' tables are missing */
if ( ( mode == FT_RENDER_MODE_LIGHT &&
!FT_DRIVER_HINTS_LIGHTLY( driver ) ) ||
if ( ( ( mode == FT_RENDER_MODE_LIGHT ||
mode == FT_RENDER_MODE_SLIGHT ) &&
!FT_DRIVER_HINTS_LIGHTLY( driver ) ) ||
( FT_IS_SFNT( face ) &&
ttface->num_locations &&
ttface->max_profile.maxSizeOfInstructions == 0 &&

3
src/pshinter/pshalgo.c
View File

@ -2149,7 +2149,8 @@
glyph->do_vert_snapping = FT_BOOL( hint_mode == FT_RENDER_MODE_MONO ||
hint_mode == FT_RENDER_MODE_LCD_V );
glyph->do_stem_adjust = FT_BOOL( hint_mode != FT_RENDER_MODE_LIGHT );
glyph->do_stem_adjust = FT_BOOL( hint_mode != FT_RENDER_MODE_LIGHT &&
hint_mode != FT_RENDER_MODE_SLIGHT );
for ( dimension = 0; dimension < 2; dimension++ )
{

3
src/smooth/ftsmooth.c
View File

@ -433,7 +433,8 @@
FT_Render_Mode mode,
const FT_Vector* origin )
{
if ( mode == FT_RENDER_MODE_LIGHT )
if ( mode == FT_RENDER_MODE_LIGHT ||
mode == FT_RENDER_MODE_SLIGHT )
mode = FT_RENDER_MODE_NORMAL;
return ft_smooth_render_generic( render, slot, mode, origin,