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Font outline decomposition fixes

This commit is contained in:
Ola Rinta-Koski 2022-01-15 12:51:09 +00:00 committed by Jeff Young
parent f3fa7febeb
commit da65fe0469
4 changed files with 103 additions and 91 deletions
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42
common/font/outline_decomposer.cpp
View File

@ -38,7 +38,8 @@ OUTLINE_DECOMPOSER::OUTLINE_DECOMPOSER( FT_Outline& aOutline ) :
static VECTOR2D toVector2D( const FT_Vector* aFreeTypeVector ) static VECTOR2D toVector2D( const FT_Vector* aFreeTypeVector )
{ {
return VECTOR2D( aFreeTypeVector->x, aFreeTypeVector->y ); return VECTOR2D( aFreeTypeVector->x * GLYPH_SIZE_SCALER,
aFreeTypeVector->y * GLYPH_SIZE_SCALER );
} }
@ -62,8 +63,7 @@ int OUTLINE_DECOMPOSER::moveTo( const FT_Vector* aEndPoint, void* aCallbackData
{ {
OUTLINE_DECOMPOSER* decomposer = static_cast<OUTLINE_DECOMPOSER*>( aCallbackData ); OUTLINE_DECOMPOSER* decomposer = static_cast<OUTLINE_DECOMPOSER*>( aCallbackData );
decomposer->m_lastEndPoint.x = aEndPoint->x; decomposer->m_lastEndPoint = toVector2D( aEndPoint );
decomposer->m_lastEndPoint.y = aEndPoint->y;
decomposer->newContour(); decomposer->newContour();
decomposer->addContourPoint( decomposer->m_lastEndPoint ); decomposer->addContourPoint( decomposer->m_lastEndPoint );
@ -76,8 +76,7 @@ int OUTLINE_DECOMPOSER::lineTo( const FT_Vector* aEndPoint, void* aCallbackData
{ {
OUTLINE_DECOMPOSER* decomposer = static_cast<OUTLINE_DECOMPOSER*>( aCallbackData ); OUTLINE_DECOMPOSER* decomposer = static_cast<OUTLINE_DECOMPOSER*>( aCallbackData );
decomposer->m_lastEndPoint.x = aEndPoint->x; decomposer->m_lastEndPoint = toVector2D( aEndPoint );
decomposer->m_lastEndPoint.y = aEndPoint->y;
decomposer->addContourPoint( decomposer->m_lastEndPoint ); decomposer->addContourPoint( decomposer->m_lastEndPoint );
@ -112,12 +111,10 @@ int OUTLINE_DECOMPOSER::cubicTo( const FT_Vector* aFirstControlPoint,
GLYPH_POINTS result; GLYPH_POINTS result;
decomposer->approximateBezierCurve( result, bezier ); decomposer->approximateBezierCurve( result, bezier );
for( const VECTOR2D& p : result ) for( const VECTOR2D& p : result )
decomposer->addContourPoint( p ); decomposer->addContourPoint( p );
decomposer->m_lastEndPoint.x = aEndPoint->x; decomposer->m_lastEndPoint = toVector2D( aEndPoint );
decomposer->m_lastEndPoint.y = aEndPoint->y;
return 0; return 0;
} }
@ -177,14 +174,12 @@ bool OUTLINE_DECOMPOSER::approximateCubicBezierCurve( GLYPH_POINTS& aResul
{ {
wxASSERT( aCubicBezier.size() == 4 ); wxASSERT( aCubicBezier.size() == 4 );
// minimumSegmentLength defines the "smoothness" of the
// curve-to-straight-segments conversion: the larger, the coarser
// TODO: find out what the minimum segment length should really be! // TODO: find out what the minimum segment length should really be!
static const int minimumSegmentLength = 50; constexpr int minimumSegmentLength = 10;
GLYPH_POINTS tmp; BEZIER_POLY converter( aCubicBezier );
BEZIER_POLY converter( aCubicBezier ); converter.GetPoly( aResult, minimumSegmentLength );
converter.GetPoly( tmp, minimumSegmentLength );
for( unsigned int i = 0; i < tmp.size(); i++ )
aResult.push_back( tmp[i] );
return true; return true;
} }
@ -242,19 +237,8 @@ int OUTLINE_DECOMPOSER::winding( const GLYPH_POINTS& aContour ) const
} }
} }
unsigned int i_prev_vertex; unsigned int i_prev_vertex = ( i_lowest_vertex + aContour.size() - 1 ) % aContour.size();
unsigned int i_next_vertex; unsigned int i_next_vertex = ( i_lowest_vertex + 1 ) % aContour.size();
// TODO: this should be done with modulo arithmetic for clarity
if( i_lowest_vertex == 0 )
i_prev_vertex = aContour.size() - 1;
else
i_prev_vertex = i_lowest_vertex - 1;
if( i_lowest_vertex == aContour.size() - 1 )
i_next_vertex = 0;
else
i_next_vertex = i_lowest_vertex + 1;
const VECTOR2D& lowest = aContour[i_lowest_vertex]; const VECTOR2D& lowest = aContour[i_lowest_vertex];
VECTOR2D prev( aContour[i_prev_vertex] ); VECTOR2D prev( aContour[i_prev_vertex] );
@ -268,7 +252,7 @@ int OUTLINE_DECOMPOSER::winding( const GLYPH_POINTS& aContour ) const
if( i_prev_vertex == i_lowest_vertex ) if( i_prev_vertex == i_lowest_vertex )
{ {
// ERROR: degenerate contour (all points are equal) // ERROR: degenerate contour (all points are colinear with equal Y coordinate)
// TODO: signal error // TODO: signal error
// for now let's just return something at random // for now let's just return something at random
return cw; return cw;

105
common/font/outline_font.cpp
View File

@ -41,21 +41,6 @@
using namespace KIFONT; using namespace KIFONT;
// The height of the KiCad stroke font is the distance between stroke endpoints for a vertical
// line of cap-height. So the cap-height of the font is actually stroke-width taller than its
// height.
// Outline fonts are normally scaled on full-height (including ascenders and descenders), so we
// need to compensate to keep them from being much smaller than their stroked counterparts.
constexpr double OUTLINE_FONT_SIZE_COMPENSATION = 1.4;
// The KiCad stroke font uses a subscript/superscript size ratio of 0.7. This ratio is also
// commonly used in LaTeX, but fonts with designed-in subscript and superscript glyphs are more
// likely to use 0.58.
// For auto-generated subscript and superscript glyphs in outline fonts we split the difference
// with 0.64.
static constexpr double SUBSCRIPT_SUPERSCRIPT_SIZE = 0.64;
FT_Library OUTLINE_FONT::m_freeType = nullptr; FT_Library OUTLINE_FONT::m_freeType = nullptr;
OUTLINE_FONT::OUTLINE_FONT() : OUTLINE_FONT::OUTLINE_FONT() :
@ -91,9 +76,6 @@ OUTLINE_FONT* OUTLINE_FONT::LoadFont( const wxString& aFontName, bool aBold, boo
FT_Error OUTLINE_FONT::loadFace( const wxString& aFontFileName ) FT_Error OUTLINE_FONT::loadFace( const wxString& aFontFileName )
{ {
m_faceScaler = m_faceSize * 64;
int subscriptFaceScaler = KiROUND( m_faceSize * 64 * SUBSCRIPT_SUPERSCRIPT_SIZE );
// TODO: check that going from wxString to char* with UTF-8 // TODO: check that going from wxString to char* with UTF-8
// conversion for filename makes sense on any/all platforms // conversion for filename makes sense on any/all platforms
FT_Error e = FT_New_Face( m_freeType, aFontFileName.mb_str( wxConvUTF8 ), 0, &m_face ); FT_Error e = FT_New_Face( m_freeType, aFontFileName.mb_str( wxConvUTF8 ), 0, &m_face );
@ -101,15 +83,13 @@ FT_Error OUTLINE_FONT::loadFace( const wxString& aFontFileName )
if( !e ) if( !e )
{ {
FT_Select_Charmap( m_face, FT_Encoding::FT_ENCODING_UNICODE ); FT_Select_Charmap( m_face, FT_Encoding::FT_ENCODING_UNICODE );
FT_Set_Char_Size( m_face, 0, m_faceScaler, 0, 0 ); // params:
// m_face = handle to face object
e = FT_New_Face( m_freeType, aFontFileName.mb_str( wxConvUTF8 ), 0, &m_subscriptFace ); // 0 = char width in 1/64th of points ( 0 = same as char height )
// faceSize() = char height in 1/64th of points
if( !e ) // GLYPH_RESOLUTION = horizontal device resolution (288dpi, 4x default)
{ // 0 = vertical device resolution ( 0 = same as horizontal )
FT_Select_Charmap( m_subscriptFace, FT_Encoding::FT_ENCODING_UNICODE ); FT_Set_Char_Size( m_face, 0, faceSize(), GLYPH_RESOLUTION, 0 );
FT_Set_Char_Size( m_subscriptFace, 0, subscriptFaceScaler, 0, 0 );
}
} }
return e; return e;
@ -125,7 +105,7 @@ double OUTLINE_FONT::ComputeOverbarVerticalPosition( double aGlyphHeight ) const
// The overbar on actual text is positioned above the bounding box of the glyphs. However, // The overbar on actual text is positioned above the bounding box of the glyphs. However,
// that's expensive to calculate so we use an estimation here (as this is only used for // that's expensive to calculate so we use an estimation here (as this is only used for
// calculating bounding boxes). // calculating bounding boxes).
return aGlyphHeight * OUTLINE_FONT_SIZE_COMPENSATION; return aGlyphHeight * m_outlineFontSizeCompensation;
} }
@ -140,7 +120,13 @@ double OUTLINE_FONT::GetInterline( double aGlyphHeight, double aLineSpacing ) co
if( GetFace()->units_per_EM ) if( GetFace()->units_per_EM )
pitch = GetFace()->height / GetFace()->units_per_EM; pitch = GetFace()->height / GetFace()->units_per_EM;
return ( aLineSpacing * aGlyphHeight * pitch * OUTLINE_FONT_SIZE_COMPENSATION ); double interline = aLineSpacing * aGlyphHeight * pitch * m_outlineFontSizeCompensation;
// FONT TODO this hack is an attempt to fix interline spacing by eyeballing it
static constexpr double interlineHackMultiplier = 1.2;
interline *= interlineHackMultiplier;
return interline;
} }
@ -235,29 +221,32 @@ VECTOR2I OUTLINE_FONT::GetTextAsGlyphs( BOX2I* aBBox, std::vector<std::unique_pt
bool aMirror, const VECTOR2I& aOrigin, bool aMirror, const VECTOR2I& aOrigin,
TEXT_STYLE_FLAGS aTextStyle ) const TEXT_STYLE_FLAGS aTextStyle ) const
{ {
VECTOR2D glyphSize = aSize;
FT_Face face = m_face;
double scaler = faceSize();
if( IsSubscript( aTextStyle ) || IsSuperscript( aTextStyle ) )
{
scaler = subscriptSize();
}
// set glyph resolution so that FT_Load_Glyph() results are good enough for decomposing
FT_Set_Char_Size( face, 0, scaler, GLYPH_RESOLUTION, 0 );
hb_buffer_t* buf = hb_buffer_create(); hb_buffer_t* buf = hb_buffer_create();
hb_buffer_add_utf8( buf, aText.c_str(), -1, 0, -1 ); hb_buffer_add_utf8( buf, aText.c_str(), -1, 0, -1 );
hb_buffer_guess_segment_properties( buf ); // guess direction, script, and language based on contents
// guess direction, script, and language based on contents
hb_buffer_guess_segment_properties( buf );
unsigned int glyphCount; unsigned int glyphCount;
hb_glyph_info_t* glyphInfo = hb_buffer_get_glyph_infos( buf, &glyphCount ); hb_glyph_info_t* glyphInfo = hb_buffer_get_glyph_infos( buf, &glyphCount );
hb_glyph_position_t* glyphPos = hb_buffer_get_glyph_positions( buf, &glyphCount ); hb_glyph_position_t* glyphPos = hb_buffer_get_glyph_positions( buf, &glyphCount );
hb_font_t* referencedFont;
VECTOR2D glyphSize = aSize; hb_font_t* referencedFont = hb_ft_font_create_referenced( face );
FT_Face face = m_face;
double scaler = m_faceScaler / OUTLINE_FONT_SIZE_COMPENSATION;
if( IsSubscript( aTextStyle ) || IsSuperscript( aTextStyle ) )
face = m_subscriptFace;
referencedFont = hb_ft_font_create_referenced( face );
hb_ft_font_set_funcs( referencedFont ); hb_ft_font_set_funcs( referencedFont );
hb_shape( referencedFont, buf, nullptr, 0 ); hb_shape( referencedFont, buf, nullptr, 0 );
const VECTOR2D scaleFactor( glyphSize.x / scaler, -glyphSize.y / scaler ); VECTOR2D scaleFactor( glyphSize.x / faceSize(), -glyphSize.y / faceSize() );
scaleFactor = scaleFactor * m_outlineFontSizeCompensation;
VECTOR2I cursor( 0, 0 ); VECTOR2I cursor( 0, 0 );
VECTOR2D topLeft( INT_MAX * 1.0, -INT_MAX * 1.0 ); VECTOR2D topLeft( INT_MAX * 1.0, -INT_MAX * 1.0 );
@ -265,21 +254,16 @@ VECTOR2I OUTLINE_FONT::GetTextAsGlyphs( BOX2I* aBBox, std::vector<std::unique_pt
for( unsigned int i = 0; i < glyphCount; i++ ) for( unsigned int i = 0; i < glyphCount; i++ )
{ {
hb_glyph_position_t& pos = glyphPos[i];
int codepoint = glyphInfo[i].codepoint;
if( aGlyphs ) if( aGlyphs )
{ {
FT_Load_Glyph( face, codepoint, FT_LOAD_NO_BITMAP ); FT_Load_Glyph( face, glyphInfo[i].codepoint, FT_LOAD_NO_BITMAP );
FT_GlyphSlot faceGlyph = face->glyph;
// contours is a collection of all outlines in the glyph; // contours is a collection of all outlines in the glyph;
// example: glyph for 'o' generally contains 2 contours, // example: glyph for 'o' generally contains 2 contours,
// one for the glyph outline and one for the hole // one for the glyph outline and one for the hole
CONTOURS contours; CONTOURS contours;
OUTLINE_DECOMPOSER decomposer( faceGlyph->outline ); OUTLINE_DECOMPOSER decomposer( face->glyph->outline );
decomposer.OutlineToSegments( &contours ); decomposer.OutlineToSegments( &contours );
std::unique_ptr<OUTLINE_GLYPH> glyph = std::make_unique<OUTLINE_GLYPH>(); std::unique_ptr<OUTLINE_GLYPH> glyph = std::make_unique<OUTLINE_GLYPH>();
@ -300,9 +284,9 @@ VECTOR2I OUTLINE_FONT::GetTextAsGlyphs( BOX2I* aBBox, std::vector<std::unique_pt
topRight.y = std::max( topRight.y, pt.y ); topRight.y = std::max( topRight.y, pt.y );
if( IsSubscript( aTextStyle ) ) if( IsSubscript( aTextStyle ) )
pt.y -= 0.25 * scaler; pt.y += m_subscriptVerticalOffset * scaler;
else if( IsSuperscript( aTextStyle ) ) else if( IsSuperscript( aTextStyle ) )
pt.y += 0.45 * scaler; pt.y += m_superscriptVerticalOffset * scaler;
pt *= scaleFactor; pt *= scaleFactor;
pt += aPosition; pt += aPosition;
@ -339,14 +323,19 @@ VECTOR2I OUTLINE_FONT::GetTextAsGlyphs( BOX2I* aBBox, std::vector<std::unique_pt
} }
} }
// FONT TODO we might not want to do Fracture() here;
// knockout text (eg. silkscreen labels with a background) will
// need to do that after the contours have been turned into holes
// and vice versa
if( glyph->HasHoles() ) if( glyph->HasHoles() )
glyph->Fracture( SHAPE_POLY_SET::PM_FAST ); // FONT TODO verify aFastMode glyph->Fracture( SHAPE_POLY_SET::PM_FAST ); // FONT TODO verify aFastMode
aGlyphs->push_back( std::move( glyph ) ); aGlyphs->push_back( std::move( glyph ) );
} }
cursor.x += pos.x_advance; hb_glyph_position_t& pos = glyphPos[i];
cursor.y += pos.y_advance; cursor.x += ( pos.x_advance * GLYPH_SIZE_SCALER );
cursor.y += ( pos.y_advance * GLYPH_SIZE_SCALER );
} }
if( IsOverbar( aTextStyle ) && aGlyphs ) if( IsOverbar( aTextStyle ) && aGlyphs )
@ -354,8 +343,8 @@ VECTOR2I OUTLINE_FONT::GetTextAsGlyphs( BOX2I* aBBox, std::vector<std::unique_pt
topLeft *= scaleFactor; topLeft *= scaleFactor;
topRight *= scaleFactor; topRight *= scaleFactor;
topLeft.y -= aSize.y * 0.16; topLeft.y -= aSize.y * m_overbarOffset;
topRight.y -= aSize.y * 0.16; topRight.y -= aSize.y * m_overbarOffset;
topLeft += aPosition; topLeft += aPosition;
topRight += aPosition; topRight += aPosition;
@ -366,7 +355,7 @@ VECTOR2I OUTLINE_FONT::GetTextAsGlyphs( BOX2I* aBBox, std::vector<std::unique_pt
RotatePoint( topRight, aOrigin, aAngle ); RotatePoint( topRight, aOrigin, aAngle );
} }
double overbarHeight = aSize.y * 0.07; double overbarHeight = aSize.y * m_overbarHeightMultiplier;
SHAPE_POLY_SET overbar; SHAPE_POLY_SET overbar;
TransformOvalToPolygon( overbar, topLeft, topRight, overbarHeight, overbarHeight / 8, TransformOvalToPolygon( overbar, topLeft, topRight, overbarHeight, overbarHeight / 8,
@ -401,9 +390,7 @@ void OUTLINE_FONT::RenderToOpenGLCanvas( KIGFX::OPENGL_GAL& aGal, const UTF8& aS
{ {
hb_buffer_t* buf = hb_buffer_create(); hb_buffer_t* buf = hb_buffer_create();
hb_buffer_add_utf8( buf, aString.c_str(), -1, 0, -1 ); hb_buffer_add_utf8( buf, aString.c_str(), -1, 0, -1 );
hb_buffer_guess_segment_properties( buf ); // guess direction, script, and language based on contents
// guess direction, script, and language based on contents
hb_buffer_guess_segment_properties( buf );
unsigned int glyphCount; unsigned int glyphCount;
hb_glyph_info_t* glyphInfo = hb_buffer_get_glyph_infos( buf, &glyphCount ); hb_glyph_info_t* glyphInfo = hb_buffer_get_glyph_infos( buf, &glyphCount );

8
include/font/glyph.h
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@ -34,6 +34,14 @@
namespace KIFONT namespace KIFONT
{ {
constexpr int GLYPH_DEFAULT_DPI = 72; ///< FreeType default
// The FreeType default of 72 DPI is not enough for outline decomposition;
// so we'll use something larger than that.
constexpr int GLYPH_RESOLUTION = 288;
constexpr double GLYPH_SIZE_SCALER = GLYPH_DEFAULT_DPI / (double) GLYPH_RESOLUTION;
class GLYPH class GLYPH
{ {
public: public:

39
include/font/outline_font.h
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@ -134,13 +134,46 @@ private:
static FT_Library m_freeType; static FT_Library m_freeType;
FT_Face m_face; FT_Face m_face;
const int m_faceSize; const int m_faceSize;
FT_Face m_subscriptFace;
int m_faceScaler;
// cache for glyphs converted to straight segments // cache for glyphs converted to straight segments
// key is glyph index (FT_GlyphSlot field glyph_index) // key is glyph index (FT_GlyphSlot field glyph_index)
std::map<unsigned int, GLYPH_POINTS_LIST> m_contourCache; std::map<unsigned int, GLYPH_POINTS_LIST> m_contourCache;
// The height of the KiCad stroke font is the distance between stroke endpoints for a vertical
// line of cap-height. So the cap-height of the font is actually stroke-width taller than its
// height.
// Outline fonts are normally scaled on full-height (including ascenders and descenders), so we
// need to compensate to keep them from being much smaller than their stroked counterparts.
static constexpr double m_outlineFontSizeCompensation = 1.4;
// FT_Set_Char_Size() gets character width and height specified in
// 1/64ths of a point
static constexpr int m_charSizeScaler = 64;
// The KiCad stroke font uses a subscript/superscript size ratio of 0.7. This ratio is also
// commonly used in LaTeX, but fonts with designed-in subscript and superscript glyphs are more
// likely to use 0.58.
// For auto-generated subscript and superscript glyphs in outline fonts we split the difference
// with 0.64.
static constexpr double m_subscriptSuperscriptSize = 0.64;
int faceSize( int aSize ) const
{
return aSize * m_charSizeScaler * m_outlineFontSizeCompensation;
};
int faceSize() const { return faceSize( m_faceSize ); }
// also for superscripts
int subscriptSize( int aSize ) const
{
return KiROUND( faceSize( aSize ) * m_subscriptSuperscriptSize );
}
int subscriptSize() const { return subscriptSize( m_faceSize ); }
static constexpr double m_subscriptVerticalOffset = -0.25;
static constexpr double m_superscriptVerticalOffset = 0.45;
static constexpr double m_overbarOffset = 0.16;
static constexpr double m_overbarHeightMultiplier = 0.07;
}; };
} //namespace KIFONT } //namespace KIFONT