spaces.c

远程桌面连接工具

       if (context != NULLCONTEXT) {
               MatrixMultiply(contexts[context].inverse, M, M);
               MatrixMultiply(M, contexts[context].normal, M);
       }
}
 
/*
:h2.Conversion from User's X,Y to "fractpel" X,Y
 
When the user is building paths (lines, moves, curves, etc.) he passes
the control points (x,y) for the paths together with an XYspace.  We
must convert from the user's (x,y) to our internal representation
which is in pels (fractpels, actually).  This involves transforming
the user's (x,y) under the coordinate space transformation.  It is
important that we do this quickly.  So, we store pointers to different
conversion functions right in the XYspace structure.  This allows us
to have simpler special case functions for the more commonly
encountered types of transformations.
 
:h3.Convert(), IConvert(), and ForceFloat() - Called Through "XYspace" Structure
 
These are functions that fit in the "convert" and "iconvert" function
pointers in the XYspace structure.  They call the "xconvert", "yconvert",
"ixconvert", and "iyconvert" as appropriate to actually do the work.
These secondary routines come in many flavors to handle different
special cases as quickly as possible.
*/
 
static void FXYConvert(pt, S, x, y)
       register struct fractpoint *pt;  /* point to set                      */
       register struct XYspace *S;  /* relevant coordinate space             */
       register double x,y;  /* user's coordinates of point                  */
{
       pt->x = (*S->xconvert)(S->tofract.normal[0][0], S->tofract.normal[1][0], x, y);
       pt->y = (*S->yconvert)(S->tofract.normal[0][1], S->tofract.normal[1][1], x, y);
}
 
static void IXYConvert(pt, S, x, y)
       register struct fractpoint *pt;  /* point to set                      */
       register struct XYspace *S;  /* relevant coordinate space             */
       register long x,y;    /* user's coordinates of point                  */
{
       pt->x = (*S->ixconvert)(S->itofract[0][0], S->itofract[1][0], x, y);
       pt->y = (*S->iyconvert)(S->itofract[0][1], S->itofract[1][1], x, y);
}
 
/*
ForceFloat is a substitute for IConvert(), when we just do not have
enough significant digits in the coefficients to get high enough
precision in the answer with fixed point arithmetic.  So, we force the
integers to floats, and do the arithmetic all with floats:
*/
 
static void ForceFloat(pt, S, x, y)
       register struct fractpoint *pt;  /* point to set                      */
       register struct XYspace *S;  /* relevant coordinate space             */
       register long x,y;    /* user's coordinates of point                  */
{
       (*S->convert)(pt, S, (double) x, (double) y);
}
 
/*
:h3.FXYboth(), FXonly(), FYonly() - Floating Point Conversion
 
These are the routines we use when the user has given us floating
point numbers for x and y. FXYboth() is the general purpose routine;
FXonly() and FYonly() are special cases when one of the coefficients
is 0.0.
*/
 
static fractpel FXYboth(cx, cy, x, y)
       register double cx,cy;  /* x and y coefficients                       */
       register double x,y;  /* user x,y                                     */
{
       register double r;    /* temporary float                              */
 
       r = x * cx + y * cy;
       return((fractpel) r);
}
 
/*ARGSUSED*/
static fractpel FXonly(cx, cy, x, y)
       register double cx,cy;  /* x and y coefficients                       */
       register double x,y;  /* user x,y                                     */
{
       register double r;    /* temporary float                              */
 
       r = x * cx;
       return((fractpel) r);
}
 
/*ARGSUSED*/
static fractpel FYonly(cx, cy, x, y)
       register double cx,cy;  /* x and y coefficients                       */
       register double x,y;  /* user x,y                                     */
{
       register double r;    /* temporary float                              */
 
       r = y * cy;
       return((fractpel) r);
}
 
/*
:h3.IXYboth(), IXonly(), IYonly() - Simple Integer Conversion
 
These are the routines we use when the user has given us integers for
x and y, and the coefficients have enough significant digits to
provide precise answers with only "long" (32 bit?) multiplication.
IXYboth() is the general purpose routine; IXonly() and IYonly() are
special cases when one of the coefficients is 0.
*/
 
static fractpel IXYboth(cx, cy, x, y)
       register fractpel cx,cy;  /* x and y coefficients                     */
       register long x,y;    /* user x,y                                     */
{
       return(x * cx + y * cy);
}
 
/*ARGSUSED*/
static fractpel IXonly(cx, cy, x, y)
       register fractpel cx,cy;  /* x and y coefficients                     */
       register long x,y;    /* user x,y                                     */
{
       return(x * cx);
}
 
/*ARGSUSED*/
static fractpel IYonly(cx, cy, x, y)
       register fractpel cx,cy;  /* x and y coefficients                     */
       register long x,y;    /* user x,y                                     */
{
       return(y * cy);
}
 
 
/*
:h3.FPXYboth(), FPXonly(), FPYonly() - More Involved Integer Conversion
 
These are the routines we use when the user has given us integers for
x and y, but the coefficients do not have enough significant digits to
provide precise answers with only "long" (32 bit?)  multiplication.
We have increased the number of significant bits in the coefficients
by FRACTBITS; therefore we must use "double long" (64 bit?)
multiplication by calling FPmult().  FPXYboth() is the general purpose
routine; FPXonly() and FPYonly() are special cases when one of the
coefficients is 0.
 
Note that it is perfectly possible for us to calculate X with the
"FP" method and Y with the "I" method, or vice versa.  It all depends
on how the functions in the XYspace structure are filled out.
*/
 
static fractpel FPXYboth(cx, cy, x, y)
       register fractpel cx,cy;  /* x and y coefficients                     */
       register long x,y;    /* user x,y                                     */
{
       return( FPmult(x, cx) + FPmult(y, cy) );
}
 
/*ARGSUSED*/
static fractpel FPXonly(cx, cy, x, y)
       register fractpel cx,cy;  /* x and y coefficients                     */
       register long x,y;    /* user x,y                                     */
{
       return( FPmult(x, cx) );
}
 
/*ARGSUSED*/
static fractpel FPYonly(cx, cy, x, y)
       register fractpel cx,cy;  /* x and y coefficients                     */
       register long x,y;    /* user x,y                                     */
{
       return( FPmult(y, cy) );
}
 
 
 
/*
:h3.FillOutFcns() - Determine the Appropriate Functions to Use for Conversion
 
This function fills out the "convert" and "iconvert" function pointers
in an XYspace structure, and also fills the "helper"
functions that actually do the work.
*/
 
static void FillOutFcns(S)
       register struct XYspace *S;  /* functions will be set in this structure */
{
       S->convert = FXYConvert;
       S->iconvert = IXYConvert;
 
       FindFfcn(S->tofract.normal[0][0], S->tofract.normal[1][0], &S->xconvert);
       FindFfcn(S->tofract.normal[0][1], S->tofract.normal[1][1], &S->yconvert);
       FindIfcn(S->tofract.normal[0][0], S->tofract.normal[1][0],
                &S->itofract[0][0], &S->itofract[1][0], &S->ixconvert);
       FindIfcn(S->tofract.normal[0][1], S->tofract.normal[1][1],
                &S->itofract[0][1], &S->itofract[1][1], &S->iyconvert);
 
       if (S->ixconvert == NULL || S->iyconvert == NULL)
                S->iconvert = ForceFloat;
}
 
/*
:h4.FindFfcn() - Subroutine of FillOutFcns() to Fill Out Floating Functions
 
This function tests for the special case of one of the coefficients
being zero:
*/
 
static void FindFfcn(cx, cy, fcnP)
       register double cx,cy;  /* x and y coefficients                       */
       register fractpel (**fcnP)();  /* pointer to function to set          */
{
       if (cx == 0.0)
               *fcnP = FYonly;
       else if (cy == 0.0)
               *fcnP = FXonly;
       else
               *fcnP = FXYboth;
}
 
/*
:h4.FindIfcn() - Subroutine of FillOutFcns() to Fill Out Integer Functions
 
There are two types of integer functions, the 'I' type and the 'FP' type.
We use the I type functions when we are satisfied with simple integer
arithmetic.  We used the FP functions when we feel we need higher
precision (but still fixed point) arithmetic.  If all else fails,
we store a NULL indicating that this we should do the conversion in
floating point.
*/
 
static void FindIfcn(cx, cy, icxP, icyP, fcnP)
       register double cx,cy;  /* x and y coefficients                       */
       register fractpel *icxP,*icyP;  /* fixed point coefficients to set    */
       register fractpel (**fcnP)();  /* pointer to function to set          */
{
       register fractpel imax;  /* maximum of cx and cy                      */
 
       *icxP = cx;
       *icyP = cy;
 
       if (cx != (float) (*icxP) || cy != (float) (*icyP)) {
/*
At this point we know our integer approximations of the coefficients
are not exact.  However, we will still use them if the maximum
coefficient will not fit in a 'fractpel'.   Of course, we have little
choice at that point, but we haven't lost that much precision by
staying with integer arithmetic.  We have enough significant digits
so that
any error we introduce is less than one part in 2:sup/16/.
*/
 
               imax = MAX(ABS(*icxP), ABS(*icyP));
               if (imax < (fractpel) (1<<(FRACTBITS-1)) ) {
/*
At this point we know our integer approximations just do not have
enough significant digits for accuracy.  We will add FRACTBITS
significant digits to the coefficients (by multiplying them by
1<<FRACTBITS) and go to the "FP" form of the functions.  First, we
check to see if we have ANY significant digits at all (that is, if
imax == 0).  If we don't, we suspect that adding FRACTBITS digits
won't help, so we punt the whole thing.
*/
                       if (imax == 0) {
                               *fcnP = NULL;
                               return;
                       }
                       cx *= FRACTFLOAT;
                       cy *= FRACTFLOAT;
                       *icxP = cx;
                       *icyP = cy;
                       *fcnP = FPXYboth;
               }
               else
                       *fcnP = IXYboth;
       }
       else
               *fcnP = IXYboth;
/*
Now we check for special cases where one coefficient is zero (after
integer conversion):
*/
       if (*icxP == 0)
               *fcnP = (*fcnP == FPXYboth) ? FPYonly : IYonly;
       else if (*icyP == 0)
               *fcnP = (*fcnP == FPXYboth) ? FPXonly : IXonly;
}
/*
:h3.UnConvert() - Find User Coordinates From FractPoints
 
The interesting thing with this routine is that we avoid calculating
the matrix inverse of the device transformation until we really need
it, which is to say, until this routine is called for the first time
with a given coordinate space.
 
We also only calculate it only once.  If the inverted matrix is valid,
we don't calculate it; if not, we do.  We never expect matrices with
zero determinants, so by convention, we mark the matrix is invalid by
marking both X terms zero.
*/
 
void UnConvert(S, pt, xp, yp)
       register struct XYspace *S;  /* relevant coordinate space             */
       register struct fractpoint *pt;  /* device coordinates                */
       double *xp,*yp;       /* where to store resulting x,y                 */
{
       double x,y;
 
       CoerceInverse(S);
       x = pt->x;
       y = pt->y;
       *xp = S->tofract.inverse[0][0] * x + S->tofract.inverse[1][0] * y;
       *yp = S->tofract.inverse[0][1] * x + S->tofract.inverse[1][1] * y;
}
 
/*
:h2.Transformations
*/
/*
:h3 id=xform.Xform() - Transform Object in X and Y
 
TYPE1IMAGER wants transformations of objects like paths to be identical
to transformations of spaces.  For example, if you scale a line(1,1)
by 10 it should yield the same result as generating the line(1,1) in
a coordinate space that has been scaled by 10.
 
We handle fonts by storing the accumulated transform, for example, SR
(accumulating on the right).  Then when we map the font through space TD,
for example, we multiply the accumulated font transform on the left by
the space transform on the right, yielding SRTD in this case.  We will
get the same result if we did S, then R, then T on the space and mapping
an unmodified font through that space.