[base] Finish experimental (disabled) BBox_Cubic_Check implementation.
* src/base/ftbbox.c (BBox_Cubic_Check): Scale arguments to improve accuracy and avoid overflows.
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ChangeLog
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ChangeLog
@ -1,9 +1,17 @@
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2013-08-15 Alexei Podtelezhnikov <apodtele@gmail.com>
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[base] Finish experimental (disabled) BBox_Cubic_Check implementation.
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* src/base/ftbbox.c (BBox_Cubic_Check): Scale arguments to improve
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accuracy and avoid overflows.
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2013-08-13 Alexei Podtelezhnikov <apodtele@gmail.com>
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[base] Refactor experimental (disabled) BBox_Cubic_Check.
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* src/base/ftbbox.c (BBox_Cubic_Check): Implement the minimum search
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as the mirror image of the maximum search.
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as the mirror image of the maximum search implemented here...
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(update_max): New function.
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2013-08-06 John Tytgat <John.Tytgat@esko.com>
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@ -275,10 +275,62 @@
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FT_Pos* min,
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FT_Pos* max )
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{
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*max = update_max( p1, p2, p3, p4, *max );
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FT_Pos nmin, nmax;
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FT_Int shift;
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/* This implementation relies on iterative bisection of the segment. */
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/* The fixed-point arithmentic of bisection is inherently stable but */
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/* may loose accuracy in the two lowest bits. To compensate, we */
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/* upscale the segment if there is room. Large values may need to be */
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/* downscaled to avoid overflows during bisection bisection. This */
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/* function is only called when a control off-point is outside the */
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/* the bbox and, thus, has the top absolute value among arguments. */
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shift = 27 - FT_MSB( FT_ABS( p2 ) | FT_ABS( p3 ) );
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if ( shift > 0 )
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{
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/* upscaling too much just wastes time */
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if ( shift > 2 )
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shift = 2;
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p1 <<= shift;
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p2 <<= shift;
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p3 <<= shift;
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p4 <<= shift;
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nmin = *min << shift;
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nmax = *max << shift;
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}
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else
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{
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p1 >>= -shift;
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p2 >>= -shift;
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p3 >>= -shift;
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p4 >>= -shift;
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nmin = *min >> -shift;
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nmax = *max >> -shift;
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}
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nmax = update_max( p1, p2, p3, p4, nmax );
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/* now flip the signs to update the minimum */
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*min = -update_max( -p1, -p2, -p3, -p4, -*min );
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nmin = -update_max( -p1, -p2, -p3, -p4, -nmin );
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if ( shift > 0 )
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{
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nmin >>= shift;
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nmax >>= shift;
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}
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else
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{
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nmin <<= -shift;
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nmax <<= -shift;
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}
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if ( nmin < *min )
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*min = nmin;
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if ( nmax > *max )
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*max = nmax;
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}
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#else
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@ -482,8 +534,9 @@
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FT_Vector* to,
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TBBox_Rec* user )
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{
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/* we don't need to check `to' since it is always an `on' point, thus */
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/* within the bbox */
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/* We don't need to check `to' since it is always an on-point, */
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/* thus within the bbox. Only segments with an off-point outside */
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/* the bbox can possibly reach new extreme values. */
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if ( CHECK_X( control1, user->bbox ) ||
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CHECK_X( control2, user->bbox ) )
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