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* src/raster/ftraster.c (Line_Up): Updated and fixed up.

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This largely synchronizes the entries into `Line_Up` and `Bezier_Up`.
Minor bugs in the remainder calculations and accumulations are fixed.
This commit is contained in:
Alexei Podtelezhnikov 2023-11-10 23:25:26 -05:00
parent d5973932d0
commit 028b0d5c1b
1 changed files with 59 additions and 79 deletions
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138
src/raster/ftraster.c
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@ -927,107 +927,87 @@
Long miny,
Long maxy )
{
Long Dx, Dy;
Int e1, e2, f1, f2, size;
Long Ix, Rx, Ax;
Long e, e2, Dx, Dy;
Long Ix, Rx, Ax;
Int size;
PLong top;
PLong top;
Dx = x2 - x1;
Dy = y2 - y1;
top = ras.top;
if ( Dy <= 0 || y2 < miny || y1 > maxy )
return SUCCESS;
if ( y2 == y1 || y2 < miny || y1 > maxy )
goto Fin;
if ( y1 < miny )
{
/* Take care: miny-y1 can be a very large value; we use */
/* a slow MulDiv function to avoid clipping bugs */
x1 += SMulDiv( Dx, miny - y1, Dy );
e1 = (Int)TRUNC( miny );
f1 = 0;
}
else
{
e1 = (Int)TRUNC( y1 );
f1 = (Int)FRAC( y1 );
}
if ( y2 > maxy )
{
/* x2 += FMulDiv( Dx, maxy - y2, Dy ); UNNECESSARY */
e2 = (Int)TRUNC( maxy );
f2 = 0;
}
else
{
e2 = (Int)TRUNC( y2 );
f2 = (Int)FRAC( y2 );
}
if ( f1 > 0 )
{
if ( e1 == e2 )
return SUCCESS;
else
{
x1 += SMulDiv( Dx, ras.precision - f1, Dy );
e1 += 1;
}
}
else
if ( ras.joint )
{
ras.top--;
ras.joint = FALSE;
}
ras.joint = (char)( f2 == 0 );
e2 = y2 > maxy ? maxy : FLOOR( y2 );
e = y1 < miny ? miny : CEILING( y1 );
if ( ras.fresh )
{
ras.cProfile->start = e1;
ras.fresh = FALSE;
ras.cProfile->start = (Int)TRUNC( e );
ras.fresh = FALSE;
}
size = e2 - e1 + 1;
if ( ras.top + size >= ras.maxBuff )
if ( y1 == e && ras.joint )
top--;
ras.joint = (Bool)( y2 == e2 );
if ( e2 < e )
goto Fin;
size = (Int)TRUNC( e2 - e ) + 1;
if ( top + size >= ras.maxBuff )
{
ras.error = FT_THROW( Raster_Overflow );
return FAILURE;
}
if ( Dx > 0 )
Dx = x2 - x1;
Dy = y2 - y1;
if ( Dx == 0 ) /* very easy */
{
Ix = SMulDiv_No_Round( ras.precision, Dx, Dy );
Rx = ( ras.precision * Dx ) % Dy;
do
*top++ = x1;
while ( --size );
goto Fin;
}
Ix = SMulDiv_No_Round( e - y1, Dx, Dy );
x1 += Ix;
*top++ = x1;
if ( --size )
{
Ax = Dx * ( e - y1 ) - Dy * Ix; /* remainder */
Ix = FMulDiv( ras.precision, Dx, Dy );
Rx = Dx * ras.precision - Dy * Ix; /* remainder */
Dx = 1;
}
else
{
Ix = -SMulDiv_No_Round( ras.precision, -Dx, Dy );
Rx = ( ras.precision * -Dx ) % Dy;
Dx = -1;
}
Ax = -Dy;
top = ras.top;
while ( size > 0 )
{
*top++ = x1;
x1 += Ix;
Ax += Rx;
if ( Ax >= 0 )
if ( x2 < x1 )
{
Ax -= Dy;
x1 += Dx;
Ax = -Ax;
Rx = -Rx;
Dx = -Dx;
}
size--;
do
{
x1 += Ix;
Ax += Rx;
if ( Ax >= Dy )
{
Ax -= Dy;
x1 += Dx;
}
*top++ = x1;
}
while ( --size );
}
Fin:
ras.top = top;
return SUCCESS;
}