#include "stdafx.h"
#include "imgutil.h"
#include "cdithtbl.h"
CDitherTable::CDitherTable() :
m_nColors( 0 ),
m_nRefCount( 0 ),
m_pnDistanceBuffer( NULL )
{
}
CDitherTable::~CDitherTable()
{
}
BOOL CDitherTable::Match( ULONG nColors, const RGBQUAD* prgbColors )
{
if( m_nColors != nColors )
{
return( FALSE );
}
if( memcmp( m_argbColors, prgbColors, m_nColors*sizeof( RGBQUAD ) ) != 0 )
{
return( FALSE );
}
return( TRUE );
}
HRESULT CDitherTable::SetColors( ULONG nColors, const RGBQUAD* prgbColors )
{
HRESULT hResult;
m_nColors = nColors;
memcpy( m_argbColors, prgbColors, m_nColors*sizeof( RGBQUAD ) );
hResult = BuildInverseMap();
if( FAILED( hResult ) )
{
return( hResult );
}
return( S_OK );
}
/*
void CDitherTable::BuildInverseMap()
{
ULONG r;
ULONG g;
ULONG b;
ULONG iColor;
ULONG iMapEntry;
int nMinDistance;
int nDistance;
int nRedDistance;
int nBlueDistance;
int nGreenDistance;
iMapEntry = 0;
for( r = 0; r < 32; r++ )
{
for( g = 0; g < 32; g++ )
{
for( b = 0; b < 32; b++ )
{
nMinDistance = 1000000;
for( iColor = 0; iColor < m_nColors; iColor++ )
{
nRedDistance = m_argbColors[iColor].rgbRed-((r<<3)+(r>>2));
nGreenDistance = m_argbColors[iColor].rgbGreen-((g<<3)+(g>>2));
nBlueDistance = m_argbColors[iColor].rgbBlue-((b<<3)+(b>>2));
nDistance = (nRedDistance*nRedDistance)+(nGreenDistance*
nGreenDistance)+(nBlueDistance*nBlueDistance);
if( nDistance < nMinDistance )
{
nMinDistance = nDistance;
m_abInverseMap[iMapEntry] = BYTE( iColor );
}
}
iMapEntry++;
}
}
}
}
*/
HRESULT CDitherTable::BuildInverseMap()
{
_ASSERTE( m_pnDistanceBuffer == NULL );
m_pnDistanceBuffer = new ULONG[32768];
if( m_pnDistanceBuffer == NULL )
{
return( E_OUTOFMEMORY );
}
inv_cmap( m_nColors, m_argbColors, 5, m_pnDistanceBuffer, m_abInverseMap );
delete m_pnDistanceBuffer;
m_pnDistanceBuffer = NULL;
return( S_OK );
}
/*****************************************************************
* TAG( inv_cmap )
*
* Compute an inverse colormap efficiently.
* Inputs:
* colors: Number of colors in the forward colormap.
* colormap: The forward colormap.
* bits: Number of quantization bits. The inverse
* colormap will have (2^bits)^3 entries.
* dist_buf: An array of (2^bits)^3 long integers to be
* used as scratch space.
* Outputs:
* rgbmap: The output inverse colormap. The entry
* rgbmap[(r<<(2*bits)) + (g<<bits) + b]
* is the colormap entry that is closest to the
* (quantized) color (r,g,b).
* Assumptions:
* Quantization is performed by right shift (low order bits are
* truncated). Thus, the distance to a quantized color is
* actually measured to the color at the center of the cell
* (i.e., to r+.5, g+.5, b+.5, if (r,g,b) is a quantized color).
* Algorithm:
* Uses a "distance buffer" algorithm:
* The distance from each representative in the forward color map
* to each point in the rgb space is computed. If it is less
* than the distance currently stored in dist_buf, then the
* corresponding entry in rgbmap is replaced with the current
* representative (and the dist_buf entry is replaced with the
* new distance).
*
* The distance computation uses an efficient incremental formulation.
*
* Distances are computed "outward" from each color. If the
* colors are evenly distributed in color space, the expected
* number of cells visited for color I is N^3/I.
* Thus, the complexity of the algorithm is O(log(K) N^3),
* where K = colors, and N = 2^bits.
*/
/*
* Here's the idea: scan from the "center" of each cell "out"
* until we hit the "edge" of the cell -- that is, the point
* at which some other color is closer -- and stop. In 1-D,
* this is simple:
* for i := here to max do
* if closer then buffer[i] = this color
* else break
* repeat above loop with i := here-1 to min by -1
*
* In 2-D, it's trickier, because along a "scan-line", the
* region might start "after" the "center" point. A picture
* might clarify:
* | ...
* | ... .
* ... .
* ... | .
* . + .
* . .
* . .
* .........
*
* The + marks the "center" of the above region. On the top 2
* lines, the region "begins" to the right of the "center".
*
* Thus, we need a loop like this:
* detect := false
* for i := here to max do
* if closer then
* buffer[..., i] := this color
* if !detect then
* here = i
* detect = true
* else
* if detect then
* break
*
* Repeat the above loop with i := here-1 to min by -1. Note that
* the "detect" value should not be reinitialized. If it was
* "true", and center is not inside the cell, then none of the
* cell lies to the left and this loop should exit
* immediately.
*
* The outer loops are similar, except that the "closer" test
* is replaced by a call to the "next in" loop; its "detect"
* value serves as the test. (No assignment to the buffer is
* done, either.)
*
* Each time an outer loop starts, the "here", "min", and
* "max" values of the next inner loop should be
* re-initialized to the center of the cell, 0, and cube size,
* respectively. Otherwise, these values will carry over from
* one "call" to the inner loop to the next. This tracks the
* edges of the cell and minimizes the number of
* "unproductive" comparisons that must be made.
*
* Finally, the inner-most loop can have the "if !detect"
* optimized out of it by splitting it into two loops: one
* that finds the first color value on the scan line that is
* in this cell, and a second that fills the cell until
* another one is closer:
* if !detect then {needed for "down" loop}
* for i := here to max do
* if closer then
* buffer[..., i] := this color
* detect := true
* break
* for i := i+1 to max do
* if closer then
* buffer[..., i] := this color
* else
* break
*
* In this implementation, each level will require the
* following variables. Variables labelled (l) are local to each
* procedure. The ? should be replaced with r, g, or b:
* cdist: The distance at the starting point.
* ?center: The value of this component of the color
* c?inc: The initial increment at the ?center position.
* ?stride: The amount to add to the buffer
* pointers (dp and rgbp) to get to the
* "next row".
* min(l): The "low edge" of the cell, init to 0
* max(l): The "high edge" of the cell, init to
* colormax-1
* detect(l): True if this row has changed some
* buffer entries.
* i(l): The index for this row.
* ?xx: The accumulated increment value.
*
* here(l): The starting index for this color. The
* following variables are associated with here,
* in the sense that they must be updated if here
* is changed.
* ?dist: The current distance for this level. The
* value of dist from the previous level (g or r,
* for level b or g) initializes dist on this
* level. Thus gdist is associated with here(b)).
* ?inc: The initial increment for the row.
*
* ?dp: Pointer into the distance buffer. The value
* from the previous level initializes this level.
* ?rgbp: Pointer into the rgb buffer. The value
* from the previous level initializes this level.
*
* The blue and green levels modify 'here-associated' variables (dp,
* rgbp, dist) on the green and red levels, respectively, when here is
* changed.
*/
/* Track minimum and maximum. */
#define MINMAX_TRACK
void CDitherTable::inv_cmap(int colors, RGBQUAD *colormap, int bits,
ULONG* dist_buf, BYTE* rgbmap )
{
int nbits = 8 - bits;
colormax = 1 << bits;
x = 1 << nbits;
xsqr = 1 << (2 * nbits);
/* Compute "strides" for accessing the arrays. */
gstride = (int) colormax;
rstride = (int) (colormax * colormax);
maxfill( dist_buf, colormax );
for ( cindex = 0; cindex < colors; cindex++ )
{
/* The caller can force certain colors in the output space to be
* omitted by setting a nonzero value for the color's 'x' component.
* This will produce a map that never refers to those colors.
* -francish, 2/16/96
*/
if (!colormap[cindex].rgbReserved)
{
/*
* Distance formula is
* (red - map[0])^2 + (green - map[1])^2 + (blue - map[2])^2
*
* Because of quantization, we will measure from the center of
* each quantized "cube", so blue distance is
* (blue + x/2 - map[2])^2,
* where x = 2^(8 - bits).
* The step size is x, so the blue increment is
* 2*x*blue - 2*x*map[2] + 2*x^2
*
* Now, b in the code below is actually blue/x, so our
* increment will be 2*(b*x^2 + x^2 - x*map[2]). For
* efficiency, we will maintain this quantity in a separate variable
* that will be updated incrementally by adding 2*x^2 each time.
*/
/* The initial position is the cell containing the colormap
* entry. We get this by quantizing the colormap values.
*/
rcenter = colormap[cindex].rgbRed >> nbits;
gcenter = colormap[cindex].rgbGreen >> nbits;
bcenter = colormap[cindex].rgbBlue >> nbits;
rdist = colormap[cindex].rgbRed - (rcenter * x + x/2);
gdist = colormap[cindex].rgbGreen - (gcenter * x + x/2);
cdist = colormap[cindex].rgbBlue - (bcenter * x + x/2);
cdist = rdist*rdist + gdist*gdist + cdist*cdist;
crinc = 2 * ((rcenter + 1) * xsqr - (colormap[cindex].rgbRed*x));
cginc = 2 * ((gcenter + 1) * xsqr - (colormap[cindex].rgbGreen*x));
cbinc = 2 * ((bcenter + 1) * xsqr - (colormap[cindex].rgbBlue*x));
/* Array starting points. */
cdp = dist_buf + rcenter * rstride + gcenter * gstride + bcenter;
crgbp = rgbmap + rcenter * rstride + gcenter * gstride + bcenter;
(void)redloop();
}
}
}
/* redloop -- loop up and down from red center. */
int CDitherTable::redloop()
{
int detect;
int r;
int first;
long txsqr = xsqr + xsqr;
detect = 0;
/* Basic loop up. */
for ( r = rcenter, rdist = cdist, rxx = crinc,
rdp = cdp, rrgbp = crgbp, first = 1;
r < (int) colormax;
r++, rdp += rstride, rrgbp += rstride,
rdist += rxx, rxx += txsqr, first = 0 )
{
if ( greenloop( first ) )
detect = 1;
else if ( detect )
break;
}
/* Basic loop down. */
for ( r = rcenter - 1, rxx = crinc - txsqr, rdist = cdist - rxx,
rdp = cdp - rstride, rrgbp = crgbp - rstride, first = 1;
r >= 0;
r--, rdp -= rstride, rrgbp -= rstride,
rxx -= txsqr, rdist -= rxx, first = 0 )
{
if ( greenloop( first ) )
detect = 1;
else if ( detect )
break;
}
return detect;
}
#undef min
#undef max
#define here greenloop_here
#define min greenloop_min
#define max greenloop_max
#define prevmin greenloop_prevmin
#define prevmax greenloop_prevmax
/* greenloop -- loop up and down from green center. */
int CDitherTable::greenloop( int restart )
{
int detect;
int g;
int first;
long txsqr = xsqr + xsqr;
#ifdef MINMAX_TRACK
int thismax, thismin;
#endif
if ( restart )
{
here = gcenter;
min = 0;
max = (int) colormax - 1;
ginc = cginc;
#ifdef MINMAX_TRACK
prevmax = 0;
prevmin = (int) colormax;
#endif
}
#ifdef MINMAX_TRACK
thismin = min;
thismax = max;
#endif
detect = 0;
/* Basic loop up. */
for ( g = here, gcdist = gdist = rdist, gxx = ginc,
gcdp = gdp = rdp, gcrgbp = grgbp = rrgbp, first = 1;
g <= max;
g++, gdp += gstride, gcdp += gstride, grgbp += gstride, gcrgbp += gstride,
gdist += gxx, gcdist += gxx, gxx += txsqr, first = 0 )
{
if ( blueloop( first ) )
{
if ( !detect )
{
/* Remember here and associated data! */
if ( g > here )
{
here = g;
rdp = gcdp;
rrgbp = gcrgbp;
rdist = gcdist;
ginc = gxx;
#ifdef MINMAX_TRACK
thismin = here;
#endif
}
detect = 1;
}
}
else if ( detect )
{
#ifdef MINMAX_TRACK
thismax = g - 1;
#endif
break;
}
}
/* Basic loop down. */
for ( g = here - 1, gxx = ginc - txsqr, gcdist = gdist = rdist - gxx,
gcdp = gdp = rdp - gstride, gcrgbp = grgbp = rrgbp - gstride,
first = 1;
g >= min;
g--, gdp -= gstride, gcdp -= gstride, grgbp -= gstride, gcrgbp -= gstride,
gxx -= txsqr, gdist -= gxx, gcdist -= gxx, first = 0 )
{
if ( blueloop( first ) )
{
if ( !detect )
{
/* Remember here! */
here = g;
rdp = gcdp;
rrgbp = gcrgbp;
rdist = gcdist;
ginc = gxx;
#ifdef MINMAX_TRACK
thismax = here;
#endif
detect = 1;
}
}
else if ( detect )
{
#ifdef MINMAX_TRACK
thismin = g + 1;
#endif
break;
}
}
#ifdef MINMAX_TRACK
/* If we saw something, update the edge trackers. For now, only
* tracks edges that are "shrinking" (min increasing, max
* decreasing.
*/
if ( detect )
{
if ( thismax < prevmax )
max = thismax;
prevmax = thismax;
if ( thismin > prevmin )
min = thismin;
prevmin = thismin;
}
#endif
return detect;
}
#undef min
#undef max
#undef here
#undef prevmin
#undef prevmax
#define here blueloop_here
#define min blueloop_min
#define max blueloop_max
#define prevmin blueloop_prevmin
#define prevmax blueloop_prevmax
/* blueloop -- loop up and down from blue center. */
int CDitherTable::blueloop( int restart )
{
int detect;
register ULONG* dp;
register BYTE* rgbp;
register long bdist, bxx;
register int b, i = cindex;
register long txsqr = xsqr + xsqr;
register int lim;
#ifdef MINMAX_TRACK
int thismin, thismax;
#endif /* MINMAX_TRACK */
if ( restart )
{
here = bcenter;
min = 0;
max = (int) colormax - 1;
binc = cbinc;
#ifdef MINMAX_TRACK
prevmin = (int) colormax;
prevmax = 0;
#endif /* MINMAX_TRACK */
}
detect = 0;
#ifdef MINMAX_TRACK
thismin = min;
thismax = max;
#endif
/* Basic loop up. */
/* First loop just finds first applicable cell. */
for ( b = here, bdist = gdist, bxx = binc, dp = gdp, rgbp = grgbp, lim = max;
b <= lim;
b++, dp++, rgbp++,
bdist += bxx, bxx += txsqr )
{
if ( *dp > (DWORD)bdist )
{
/* Remember new 'here' and associated data! */
if ( b > here )
{
here = b;
gdp = dp;
grgbp = rgbp;
gdist = bdist;
binc = bxx;
#ifdef MINMAX_TRACK
thismin = here;
#endif
}
detect = 1;
break;
}
}
/* Second loop fills in a run of closer cells. */
for ( ;
b <= lim;
b++, dp++, rgbp++,
bdist += bxx, bxx += txsqr )
{
if ( *dp > (DWORD)bdist )
{
*dp = bdist;
*rgbp = (BYTE) i;
}
else
{
#ifdef MINMAX_TRACK
thismax = b - 1;
#endif
break;
}
}
/* Basic loop down. */
/* Do initializations here, since the 'find' loop might not get
* executed.
*/
lim = min;
b = here - 1;
bxx = binc - txsqr;
bdist = gdist - bxx;
dp = gdp - 1;
rgbp = grgbp - 1;
/* The 'find' loop is executed only if we didn't already find
* something.
*/
if ( !detect )
for ( ;
b >= lim;
b--, dp--, rgbp--,
bxx -= txsqr, bdist -= bxx )
{
if ( *dp > (DWORD)bdist )
{
/* Remember here! */
/* No test for b against here necessary because b <
* here by definition.
*/
here = b;
gdp = dp;
grgbp = rgbp;
gdist = bdist;
binc = bxx;
#ifdef MINMAX_TRACK
thismax = here;
#endif
detect = 1;
break;
}
}
/* The 'update' loop. */
for ( ;
b >= lim;
b--, dp--, rgbp--,
bxx -= txsqr, bdist -= bxx )
{
if ( *dp > (DWORD)bdist )
{
*dp = bdist;
*rgbp = (BYTE) i;
}
else
{
#ifdef MINMAX_TRACK
thismin = b + 1;
#endif
break;
}
}
/* If we saw something, update the edge trackers. */
#ifdef MINMAX_TRACK
if ( detect )
{
/* Only tracks edges that are "shrinking" (min increasing, max
* decreasing.
*/
if ( thismax < prevmax )
max = thismax;
if ( thismin > prevmin )
min = thismin;
/* Remember the min and max values. */
prevmax = thismax;
prevmin = thismin;
}
#endif /* MINMAX_TRACK */
return detect;
}
void CDitherTable::maxfill( ULONG* buffer, long side)
{
register unsigned long maxv = (unsigned long)~0L;
register long i;
register ULONG* bp;
(void)side;
for ( i = colormax * colormax * colormax, bp = buffer;
i > 0;
i--, bp++ )
*bp = maxv;
}