Source code of Windows XP (NT5)
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/* DITHER.C
Frosting: Master Theme Selector for Windows '95
Copyright (c) 1994-1998 Microsoft Corporation. All rights reserved.
*/
#include <windows.h>
#include <windowsx.h>
#ifdef DBG
#define _DEBUG
#endif
#ifdef DEBUG
#define _DEBUG
#endif
#ifdef _DEBUG
#include <mmsystem.h>
#define TIMESTART(sz) { TCHAR szTime[80]; DWORD time = timeGetTime();
#define TIMESTOP(sz) time = timeGetTime() - time; wsprintf(szTime, TEXT("%s took %d.%03d sec\r\n"), sz, time/1000, time%1000); OutputDebugString(szTime); }
#else
#define TIMESTART(sz)
#define TIMESTOP(sz)
#endif
//-----------------------------------------------------------------------------
// helpers
//-----------------------------------------------------------------------------
__inline UINT Clamp8(int z)
{
return (UINT)(((z) < 0) ? 0 : (((z) > 255) ? 255 : (z)));
}
__inline WORD rgb555(r, g, b)
{
return (((WORD)(r) << 10) | ((WORD)(g) << 5) | (WORD)(b));
}
//-----------------------------------------------------------------------------
// Rounding stuff
//-----------------------------------------------------------------------------
//
// round an 8bit value to a 5bit value with good distribution
//
#pragma data_seg(".text", "CODE")
BYTE aRound8to5[] = {
0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2,
2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4,
4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 6, 6,
6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 8, 8,
8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 10,
10, 10, 10, 10, 10, 10, 10, 11, 11, 11, 11, 11, 11, 11, 11, 12,
12, 12, 12, 12, 12, 12, 12, 13, 13, 13, 13, 13, 13, 13, 13, 13,
14, 14, 14, 14, 14, 14, 14, 14, 15, 15, 15, 15, 15, 15, 15, 15,
16, 16, 16, 16, 16, 16, 16, 16, 17, 17, 17, 17, 17, 17, 17, 17,
18, 18, 18, 18, 18, 18, 18, 18, 18, 19, 19, 19, 19, 19, 19, 19,
19, 20, 20, 20, 20, 20, 20, 20, 20, 21, 21, 21, 21, 21, 21, 21,
21, 22, 22, 22, 22, 22, 22, 22, 22, 22, 23, 23, 23, 23, 23, 23,
23, 23, 24, 24, 24, 24, 24, 24, 24, 24, 25, 25, 25, 25, 25, 25,
25, 25, 26, 26, 26, 26, 26, 26, 26, 26, 27, 27, 27, 27, 27, 27,
27, 27, 27, 28, 28, 28, 28, 28, 28, 28, 28, 29, 29, 29, 29, 29,
29, 29, 29, 30, 30, 30, 30, 30, 30, 30, 30, 31, 31, 31, 31, 31,
};
#pragma data_seg()
//
// complement of table above
//
#pragma data_seg(".text", "CODE")
BYTE aRound5to8[] = {
0, 8, 16, 25, 33, 41, 49, 58, 66, 74, 82, 90, 99,107,115,123,
132,140,148,156,165,173,181,189,197,206,214,222,230,239,247,255,
};
#pragma data_seg()
//-----------------------------------------------------------------------------
// RoundPixel555
//-----------------------------------------------------------------------------
__inline WORD RoundPixel555(int r, int g, int b)
{
return rgb555(aRound8to5[r], aRound8to5[g], aRound8to5[b]);
}
//-----------------------------------------------------------------------------
// Round24from555
//-----------------------------------------------------------------------------
__inline void Round24from555(RGBQUAD *out, WORD in)
{
out->rgbBlue = aRound5to8[ (in) & 0x1f];
out->rgbGreen = aRound5to8[ (in >> 5) & 0x1f];
out->rgbRed = aRound5to8[(in >> 10) & 0x1f];
}
/******************************Public*Routine******************************\
* 16bpp dither stuff
*
* pimped from dibengine
*
\**************************************************************************/
//
// map a 8bit value (0-255) to a 5bit value (0-31) *evenly*
//
// if (i < 8) return 0;
// if (i == 255) return 31;
// return (i-8)/8;
//
#pragma data_seg(".text", "CODE")
BYTE aMap8to5[] = {
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2,
3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4,
5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6,
7, 7, 7, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8,
9, 9, 9, 9, 9, 9, 9, 9, 10, 10, 10, 10, 10, 10, 10, 10,
11, 11, 11, 11, 11, 11, 11, 11, 12, 12, 12, 12, 12, 12, 12, 12,
13, 13, 13, 13, 13, 13, 13, 13, 14, 14, 14, 14, 14, 14, 14, 14,
15, 15, 15, 15, 15, 15, 15, 15, 16, 16, 16, 16, 16, 16, 16, 16,
17, 17, 17, 17, 17, 17, 17, 17, 18, 18, 18, 18, 18, 18, 18, 18,
19, 19, 19, 19, 19, 19, 19, 19, 20, 20, 20, 20, 20, 20, 20, 20,
21, 21, 21, 21, 21, 21, 21, 21, 22, 22, 22, 22, 22, 22, 22, 22,
23, 23, 23, 23, 23, 23, 23, 23, 24, 24, 24, 24, 24, 24, 24, 24,
25, 25, 25, 25, 25, 25, 25, 25, 26, 26, 26, 26, 26, 26, 26, 26,
27, 27, 27, 27, 27, 27, 27, 27, 28, 28, 28, 28, 28, 28, 28, 28,
29, 29, 29, 29, 29, 29, 29, 29, 30, 30, 30, 30, 30, 30, 30, 31,
};
#pragma data_seg()
//
// map a 5bit value back to a 8bit value
//
// if (i==0) return 0;
// if (i==31) return 255;
// return i*8+8;
//
#pragma data_seg(".text", "CODE")
BYTE aMap5to8[] = {
0, 16, 24, 32, 40, 48, 56, 64, 72, 80, 88, 96,104,112,120,128,
136,144,152,160,168,176,184,192,200,208,216,224,232,240,248,255,
};
#pragma data_seg()
//
// halftone table for 16bpp dithers
//
#pragma data_seg(".text", "CODE")
BYTE aHalftone16[4][4] = {
0, 4, 1, 5,
6, 2, 7, 3,
1, 5, 0, 4,
7, 3, 6, 2,
};
#pragma data_seg()
/******************************Public*Routine******************************\
* Dither555
*
\**************************************************************************/
__inline WORD
Dither555(BYTE r, BYTE re, BYTE g, BYTE ge, BYTE b, BYTE be, BYTE e)
{
return rgb555(r + (re > e), g + (ge > e), b + (be > e));
}
/******************************Public*Routine******************************\
* DitherPixel555
*
* Takes RGB and x/y coords
* and produces an appropriate 555 pixel.
*
\**************************************************************************/
__inline WORD DitherPixel555(int rs, int gs, int bs, int x, int y)
{
BYTE r = aMap8to5[rs];
BYTE re = rs - aMap5to8[r];
BYTE g = aMap8to5[gs];
BYTE ge = gs - aMap5to8[g];
BYTE b = aMap8to5[bs];
BYTE be = bs - aMap5to8[b];
return Dither555(r, re, g, ge, b, be, aHalftone16[x % 4][y % 4]);
}
///////////////////////////////////////////////////////////////////////////////
typedef struct {int r, g, b;} ERRBUF;
///////////////////////////////////////////////////////////////////////////////
void DitherScan(LPBYTE dst, LPBYTE src, RGBQUAD *colors, LPBYTE map,
ERRBUF *cur_err, ERRBUF *nxt_err, int dx, int y, BOOL f8bpp, BOOL fOrder16)
{
RGBQUAD rgbChosen, *pChosen = &rgbChosen;
WORD wColor16;
int er,eg,eb;
int r, g, b;
int x;
for (x=0; x<dx; x++)
{
r = Clamp8((int)src[2] + cur_err[x].r / 16);
g = Clamp8((int)src[1] + cur_err[x].g / 16);
b = Clamp8((int)src[0] + cur_err[x].b / 16);
wColor16 = (fOrder16? DitherPixel555(r,g,b,x,y) : RoundPixel555(r,g,b));
if (f8bpp)
pChosen = colors + (*dst++ = map[wColor16]);
else
Round24from555(pChosen, (*((WORD *)dst)++ = wColor16));
er = r - (int)pChosen->rgbRed;
eg = g - (int)pChosen->rgbGreen;
eb = b - (int)pChosen->rgbBlue;
cur_err[x+1].r += er * 7;
cur_err[x+1].g += eg * 7;
cur_err[x+1].b += eb * 7;
nxt_err[x-1].r += er * 3;
nxt_err[x-1].g += eg * 3;
nxt_err[x-1].b += eb * 3;
nxt_err[x+0].r += er * 5;
nxt_err[x+0].g += eg * 5;
nxt_err[x+0].b += eb * 5;
nxt_err[x+1].r += er * 1;
nxt_err[x+1].g += eg * 1;
nxt_err[x+1].b += eb * 1;
src+=3;
}
}
///////////////////////////////////////////////////////////////////////////////
void DitherEngine(LPBYTE dst, LPBYTE src, RGBQUAD *colors, LPBYTE map,
int dx, int dy, int dx_bytes, BOOL f8bpp, BOOL fOrder16)
{
ERRBUF *buf;
ERRBUF *err0;
ERRBUF *err1;
ERRBUF *cur_err;
ERRBUF *nxt_err;
int src_next_scan;
int y, i;
src_next_scan = (dx*3+3)&~3;
buf = (ERRBUF *)LocalAlloc(LPTR, sizeof(ERRBUF) * (dx+2) * 2);
if (buf)
{
err0 = cur_err = buf+1;
err1 = nxt_err = buf+1 + dx + 2;
/* read line by line, quantize, and transfer */
for (y=0; y<dy; y++)
{
DitherScan(dst, src, colors, map, cur_err, nxt_err, dx, y,
f8bpp, fOrder16);
src += src_next_scan;
dst += dx_bytes;
cur_err = nxt_err;
nxt_err = cur_err == err0 ? err1 : err0;
for (i=-1; i<=dx; i++)
nxt_err[i].r = nxt_err[i].g = nxt_err[i].b = 0;
}
LocalFree((HLOCAL)buf);
}
}
///////////////////////////////////////////////////////////////////////////////
// note that this layout has scanlines DWORD aligned
#define INVMAP_IMAGE_PELS (0x8000)
#define INVMAP_IMAGE_X (0x0100)
#define INVMAP_IMAGE_Y (INVMAP_IMAGE_PELS / INVMAP_IMAGE_X)
HBITMAP CreateInverseMapping(BYTE **ppMap, HDC hdcColors)
{
BOOL fResult = FALSE;
HBITMAP hbmDst, hbmOldColors;
HDC hdcSrc;
*ppMap = NULL;
if ((hbmDst = CreateCompatibleBitmap(hdcColors,
INVMAP_IMAGE_X, INVMAP_IMAGE_Y)) == NULL)
{
return NULL;
}
hbmOldColors = SelectBitmap(hdcColors, hbmDst);
if ((hdcSrc = CreateCompatibleDC(NULL)) != NULL)
{
WORD *pSrc;
BITMAPINFO bmiSrc = {sizeof(BITMAPINFOHEADER), INVMAP_IMAGE_X,
INVMAP_IMAGE_Y, 1, 16, BI_RGB, 0, 0, 0, 0, 0};
HBITMAP hbmSrc = CreateDIBSection(hdcColors, &bmiSrc, DIB_RGB_COLORS,
&pSrc, NULL, 0);
if (hbmSrc)
{
BITMAP bmDst;
if (GetObject(hbmDst, sizeof(bmDst), &bmDst))
{
HBITMAP hbmOldSrc = SelectBitmap(hdcSrc, hbmSrc);
UINT u = 0;
while (u < INVMAP_IMAGE_PELS)
*pSrc++ = (WORD)u++;
BitBlt(hdcColors, 0, 0, INVMAP_IMAGE_X, INVMAP_IMAGE_Y, hdcSrc,
0, 0, SRCCOPY);
*ppMap = (BYTE *)bmDst.bmBits;
SelectBitmap(hdcSrc, hbmOldSrc);
}
DeleteBitmap(hbmSrc);
}
DeleteDC(hdcSrc);
}
SelectBitmap(hdcColors, hbmOldColors);
if (*ppMap)
return hbmDst;
DeleteBitmap(hbmDst);
return NULL;
}
///////////////////////////////////////////////////////////////////////////////
BOOL DitherImage(HDC hdcDst, HBITMAP hbmDst, LPBITMAPINFOHEADER lpbiSrc,
LPBYTE lpbSrc, BOOL fOrder16)
{
BOOL fResult = FALSE;
BITMAP bmDst;
if (lpbiSrc->biBitCount != 24)
return FALSE;
if (GetObject(hbmDst, sizeof(bmDst), &bmDst))
{
if ((lpbiSrc->biWidth == bmDst.bmWidth) &&
(lpbiSrc->biHeight == bmDst.bmHeight) &&
((bmDst.bmBitsPixel == 16) || (bmDst.bmBitsPixel == 8)))
{
RGBQUAD rgbColors[256];
HBITMAP hbmMap = NULL;
BYTE *pMap;
BOOL f8bpp = (bmDst.bmBitsPixel == 8);
if (f8bpp)
{
TIMESTART(TEXT("CreateInverseMap"));
if ((hbmMap = CreateInverseMapping(&pMap, hdcDst)) == NULL)
goto error;
GetDIBColorTable(hdcDst, 0, 256, rgbColors);
TIMESTOP(TEXT("CreateInverseMap"));
}
DitherEngine((LPBYTE)bmDst.bmBits, lpbSrc, rgbColors, pMap,
bmDst.bmWidth, bmDst.bmHeight, bmDst.bmWidthBytes,
f8bpp, fOrder16);
if (hbmMap)
DeleteBitmap(hbmMap);
fResult = TRUE;
error:
; // make the compiler happy it wants a statement here
}
}
return fResult;
}