1 /***************************************************************************/
5 /* Adobe's code for font instances (body). */
7 /* Copyright 2007-2014 Adobe Systems Incorporated. */
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10 /* object code form as indicated by the copyright notice(s) included */
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36 /***************************************************************************/
40 #include FT_INTERNAL_CALC_H
50 /* Compute a stem darkening amount in character space. */
52 cf2_computeDarkening( CF2_Fixed emRatio
,
55 CF2_Fixed
* darkenAmount
,
56 CF2_Fixed boldenAmount
,
58 FT_Int
* darkenParams
)
61 * Total darkening amount is computed in 1000 unit character space
62 * using the modified 5 part curve as Adobe's Avalon rasterizer.
63 * The darkening amount is smaller for thicker stems.
64 * It becomes zero when the stem is thicker than 2.333 pixels.
68 * darkenAmount = 0.4 pixels if scaledStem <= 0.5 pixels,
69 * darkenAmount = 0.275 pixels if 1 <= scaledStem <= 1.667 pixels,
70 * darkenAmount = 0 pixel if scaledStem >= 2.333 pixels,
72 * and piecewise linear in-between:
87 * | +-----------------
89 * +---------------------------------------------> stem
93 * This corresponds to the following values for the
94 * `darkening-parameters' property:
96 * (x1, y1) = (500, 400)
97 * (x2, y2) = (1000, 275)
98 * (x3, y3) = (1667, 275)
99 * (x4, y4) = (2333, 0)
103 /* Internal calculations are done in units per thousand for */
104 /* convenience. The x axis is scaled stem width in */
105 /* thousandths of a pixel. That is, 1000 is 1 pixel. */
106 /* The y axis is darkening amount in thousandths of a pixel.*/
107 /* In the code, below, dividing by ppem and */
108 /* adjusting for emRatio converts darkenAmount to character */
109 /* space (font units). */
110 CF2_Fixed stemWidthPer1000
, scaledStem
;
116 if ( boldenAmount
== 0 && !stemDarkened
)
119 /* protect against range problems and divide by zero */
120 if ( emRatio
< cf2_doubleToFixed( .01 ) )
125 FT_Int x1
= darkenParams
[0];
126 FT_Int y1
= darkenParams
[1];
127 FT_Int x2
= darkenParams
[2];
128 FT_Int y2
= darkenParams
[3];
129 FT_Int x3
= darkenParams
[4];
130 FT_Int y3
= darkenParams
[5];
131 FT_Int x4
= darkenParams
[6];
132 FT_Int y4
= darkenParams
[7];
135 /* convert from true character space to 1000 unit character space; */
136 /* add synthetic emboldening effect */
138 /* `stemWidthPer1000' will not overflow for a legitimate font */
140 stemWidthPer1000
= FT_MulFix( stemWidth
+ boldenAmount
, emRatio
);
142 /* `scaledStem' can easily overflow, so we must clamp its maximum */
143 /* value; the test doesn't need to be precise, but must be */
144 /* conservative. The clamp value (default 2333) where */
145 /* `darkenAmount' is zero is well below the overflow value of */
148 /* FT_MSB computes the integer part of the base 2 logarithm. The */
149 /* number of bits for the product is 1 or 2 more than the sum of */
150 /* logarithms; remembering that the 16 lowest bits of the fraction */
151 /* are dropped this is correct to within a factor of almost 4. */
152 /* For example, 0x80.0000 * 0x80.0000 = 0x4000.0000 is 23+23 and */
153 /* is flagged as possible overflow because 0xFF.FFFF * 0xFF.FFFF = */
154 /* 0xFFFF.FE00 is also 23+23. */
156 logBase2
= FT_MSB( (FT_UInt32
)stemWidthPer1000
) +
157 FT_MSB( (FT_UInt32
)ppem
);
159 if ( logBase2
>= 46 )
160 /* possible overflow */
161 scaledStem
= cf2_intToFixed( x4
);
163 scaledStem
= FT_MulFix( stemWidthPer1000
, ppem
);
165 /* now apply the darkening parameters */
167 if ( scaledStem
< cf2_intToFixed( x1
) )
168 *darkenAmount
= FT_DivFix( cf2_intToFixed( y1
), ppem
);
170 else if ( scaledStem
< cf2_intToFixed( x2
) )
172 FT_Int xdelta
= x2
- x1
;
173 FT_Int ydelta
= y2
- y1
;
174 FT_Int x
= stemWidthPer1000
-
175 FT_DivFix( cf2_intToFixed( x1
), ppem
);
181 *darkenAmount
= FT_MulDiv( x
, ydelta
, xdelta
) +
182 FT_DivFix( cf2_intToFixed( y1
), ppem
);
185 else if ( scaledStem
< cf2_intToFixed( x3
) )
189 FT_Int xdelta
= x3
- x2
;
190 FT_Int ydelta
= y3
- y2
;
191 FT_Int x
= stemWidthPer1000
-
192 FT_DivFix( cf2_intToFixed( x2
), ppem
);
198 *darkenAmount
= FT_MulDiv( x
, ydelta
, xdelta
) +
199 FT_DivFix( cf2_intToFixed( y2
), ppem
);
203 else if ( scaledStem
< cf2_intToFixed( x4
) )
207 FT_Int xdelta
= x4
- x3
;
208 FT_Int ydelta
= y4
- y3
;
209 FT_Int x
= stemWidthPer1000
-
210 FT_DivFix( cf2_intToFixed( x3
), ppem
);
216 *darkenAmount
= FT_MulDiv( x
, ydelta
, xdelta
) +
217 FT_DivFix( cf2_intToFixed( y3
), ppem
);
224 *darkenAmount
= FT_DivFix( cf2_intToFixed( y4
), ppem
);
227 /* use half the amount on each side and convert back to true */
228 /* character space */
229 *darkenAmount
= FT_DivFix( *darkenAmount
, 2 * emRatio
);
232 /* add synthetic emboldening effect in character space */
233 *darkenAmount
+= boldenAmount
/ 2;
237 /* set up values for the current FontDict and matrix; */
238 /* called for each glyph to be rendered */
240 /* caller's transform is adjusted for subpixel positioning */
242 cf2_font_setup( CF2_Font font
,
243 const CF2_Matrix
* transform
)
245 /* pointer to parsed font object */
246 PS_Decoder
* decoder
= font
->decoder
;
248 FT_Bool needExtraSetup
= FALSE
;
250 CFF_VStoreRec
* vstore
;
251 FT_Bool hasVariations
= FALSE
;
253 /* character space units */
254 CF2_Fixed boldenX
= font
->syntheticEmboldeningAmountX
;
255 CF2_Fixed boldenY
= font
->syntheticEmboldeningAmountY
;
260 CF2_UInt lenNormalizedV
= 0;
261 FT_Fixed
* normalizedV
= NULL
;
263 /* clear previous error */
264 font
->error
= FT_Err_Ok
;
266 /* if a CID fontDict has changed, we need to recompute some cached */
268 subFont
= cf2_getSubfont( decoder
);
269 if ( font
->lastSubfont
!= subFont
)
271 font
->lastSubfont
= subFont
;
272 needExtraSetup
= TRUE
;
277 FT_Service_CFFLoad cffload
= (FT_Service_CFFLoad
)font
->cffload
;
280 /* check for variation vectors */
281 vstore
= cf2_getVStore( decoder
);
282 hasVariations
= ( vstore
->dataCount
!= 0 );
286 #ifdef TT_CONFIG_OPTION_GX_VAR_SUPPORT
287 /* check whether Private DICT in this subfont needs to be reparsed */
288 font
->error
= cf2_getNormalizedVector( decoder
,
294 if ( cffload
->blend_check_vector( &subFont
->blend
,
295 subFont
->private_dict
.vsindex
,
299 /* blend has changed, reparse */
300 cffload
->load_private_dict( decoder
->cff
,
304 needExtraSetup
= TRUE
;
308 /* copy from subfont */
309 font
->blend
.font
= subFont
->blend
.font
;
311 /* clear state of charstring blend */
312 font
->blend
.usedBV
= FALSE
;
314 /* initialize value for charstring */
315 font
->vsindex
= subFont
->private_dict
.vsindex
;
317 /* store vector inputs for blends in charstring */
318 font
->lenNDV
= lenNormalizedV
;
319 font
->NDV
= normalizedV
;
323 /* if ppem has changed, we need to recompute some cached data */
324 /* note: because of CID font matrix concatenation, ppem and transform */
325 /* do not necessarily track. */
326 ppem
= cf2_getPpemY( decoder
);
327 if ( font
->ppem
!= ppem
)
330 needExtraSetup
= TRUE
;
333 /* copy hinted flag on each call */
334 font
->hinted
= (FT_Bool
)( font
->renderingFlags
& CF2_FlagsHinted
);
336 /* determine if transform has changed; */
337 /* include Fontmatrix but ignore translation */
338 if ( ft_memcmp( transform
,
339 &font
->currentTransform
,
340 4 * sizeof ( CF2_Fixed
) ) != 0 )
342 /* save `key' information for `cache of one' matrix data; */
343 /* save client transform, without the translation */
344 font
->currentTransform
= *transform
;
345 font
->currentTransform
.tx
=
346 font
->currentTransform
.ty
= cf2_intToFixed( 0 );
348 /* TODO: FreeType transform is simple scalar; for now, use identity */
350 font
->innerTransform
= *transform
;
351 font
->outerTransform
.a
=
352 font
->outerTransform
.d
= cf2_intToFixed( 1 );
353 font
->outerTransform
.b
=
354 font
->outerTransform
.c
= cf2_intToFixed( 0 );
356 needExtraSetup
= TRUE
;
360 * font->darkened is set to true if there is a stem darkening request or
361 * the font is synthetic emboldened.
362 * font->darkened controls whether to adjust blue zones, winding order,
366 if ( font
->stemDarkened
!= ( font
->renderingFlags
& CF2_FlagsDarkened
) )
369 (FT_Bool
)( font
->renderingFlags
& CF2_FlagsDarkened
);
371 /* blue zones depend on darkened flag */
372 needExtraSetup
= TRUE
;
375 /* recompute variables that are dependent on transform or FontDict or */
377 if ( needExtraSetup
)
379 /* StdVW is found in the private dictionary; */
380 /* recompute darkening amounts whenever private dictionary or */
381 /* transform change */
382 /* Note: a rendering flag turns darkening on or off, so we want to */
383 /* store the `on' amounts; */
384 /* darkening amount is computed in character space */
385 /* TODO: testing size-dependent darkening here; */
386 /* what to do for rotations? */
390 CF2_Int unitsPerEm
= font
->unitsPerEm
;
393 if ( unitsPerEm
== 0 )
396 ppem
= FT_MAX( cf2_intToFixed( 4 ),
397 font
->ppem
); /* use minimum ppem of 4 */
400 /* since vstem is measured in the x-direction, we use the `a' member */
401 /* of the fontMatrix */
402 emRatio
= cf2_fixedFracMul( cf2_intToFixed( 1000 ), fontMatrix
->a
);
405 /* Freetype does not preserve the fontMatrix when parsing; use */
406 /* unitsPerEm instead. */
407 /* TODO: check precision of this */
408 emRatio
= cf2_intToFixed( 1000 ) / unitsPerEm
;
409 font
->stdVW
= cf2_getStdVW( decoder
);
411 if ( font
->stdVW
<= 0 )
412 font
->stdVW
= FT_DivFix( cf2_intToFixed( 75 ), emRatio
);
416 /* Ensure that boldenX is at least 1 pixel for synthetic bold font */
417 /* (similar to what Avalon does) */
418 boldenX
= FT_MAX( boldenX
,
419 FT_DivFix( cf2_intToFixed( unitsPerEm
), ppem
) );
421 /* Synthetic emboldening adds at least 1 pixel to darkenX, while */
422 /* stem darkening adds at most half pixel. Since the purpose of */
423 /* stem darkening (readability at small sizes) is met with */
424 /* synthetic emboldening, no need to add stem darkening for a */
425 /* synthetic bold font. */
426 cf2_computeDarkening( emRatio
,
432 font
->darkenParams
);
435 cf2_computeDarkening( emRatio
,
441 font
->darkenParams
);
444 /* since hstem is measured in the y-direction, we use the `d' member */
445 /* of the fontMatrix */
446 /* TODO: use the same units per em as above; check this */
447 emRatio
= cf2_fixedFracMul( cf2_intToFixed( 1000 ), fontMatrix
->d
);
450 /* set the default stem width, because it must be the same for all */
451 /* family members; */
452 /* choose a constant for StdHW that depends on font contrast */
453 stdHW
= cf2_getStdHW( decoder
);
455 if ( stdHW
> 0 && font
->stdVW
> MUL_INT32( 2, stdHW
) )
456 font
->stdHW
= FT_DivFix( cf2_intToFixed( 75 ), emRatio
);
459 /* low contrast font gets less hstem darkening */
460 font
->stdHW
= FT_DivFix( cf2_intToFixed( 110 ), emRatio
);
463 cf2_computeDarkening( emRatio
,
469 font
->darkenParams
);
471 if ( font
->darkenX
!= 0 || font
->darkenY
!= 0 )
472 font
->darkened
= TRUE
;
474 font
->darkened
= FALSE
;
476 font
->reverseWinding
= FALSE
; /* initial expectation is CCW */
478 /* compute blue zones for this instance */
479 cf2_blues_init( &font
->blues
, font
);
481 } /* needExtraSetup */
485 /* equivalent to AdobeGetOutline */
486 FT_LOCAL_DEF( FT_Error
)
487 cf2_getGlyphOutline( CF2_Font font
,
488 CF2_Buffer charstring
,
489 const CF2_Matrix
* transform
,
490 CF2_F16Dot16
* glyphWidth
)
492 FT_Error lastError
= FT_Err_Ok
;
494 FT_Vector translation
;
497 FT_Vector advancePoint
;
500 CF2_Fixed advWidth
= 0;
504 /* Note: use both integer and fraction for outlines. This allows bbox */
505 /* to come out directly. */
507 translation
.x
= transform
->tx
;
508 translation
.y
= transform
->ty
;
510 /* set up values based on transform */
511 cf2_font_setup( font
, transform
);
513 goto exit
; /* setup encountered an error */
515 /* reset darken direction */
516 font
->reverseWinding
= FALSE
;
518 /* winding order only affects darkening */
519 needWinding
= font
->darkened
;
523 /* reset output buffer */
524 cf2_outline_reset( &font
->outline
);
526 /* build the outline, passing the full translation */
527 cf2_interpT2CharString( font
,
529 (CF2_OutlineCallbacks
)&font
->outline
,
542 /* check winding order */
543 if ( font
->outline
.root
.windingMomentum
>= 0 ) /* CFF is CCW */
546 /* invert darkening and render again */
547 /* TODO: this should be a parameter to getOutline-computeOffset */
548 font
->reverseWinding
= TRUE
;
550 needWinding
= FALSE
; /* exit after next iteration */
553 /* finish storing client outline */
554 cf2_outline_close( &font
->outline
);
557 /* FreeType just wants the advance width; there is no translation */
558 *glyphWidth
= advWidth
;
560 /* free resources and collect errors from objects we've used */
561 cf2_setError( &font
->error
, lastError
);