Leaked source code of windows server 2003
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/*--------------------------------------------------------------------------*\
| RLE.C - RLE Delta frame code |
|@@BEGIN_MSINTERNAL |
| |
| History: |
| 01/01/88 toddla Created |
| 10/30/90 davidmay Reorganized, rewritten somewhat. |
| 07/11/91 dannymi Un-hacked |
| 09/15/91 ToddLa Re-hacked |
|@@END_MSINTERNAL |
\*--------------------------------------------------------------------------*/
/**************************************************************************
*
* THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY
* KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR
* PURPOSE.
*
* Copyright (c) 1991 - 1995 Microsoft Corporation. All Rights Reserved.
*
**************************************************************************/
#include <windows.h>
#include <windowsx.h>
#include <memory.h> // for _fmemcmp()
#include "msrle.h"
#define RLE_ESCAPE 0
#define RLE_EOL 0
#define RLE_EOF 1
#define RLE_JMP 2
#define RLE_RUN 3
typedef BYTE huge * HPRLE;
typedef BYTE far * LPRLE;
RGBTOL gRgbTol = {0, 0};
//
// RleDeltaFrame
//
// Calculate the RLE bits to go from hdib1 to hdib2
//
// hdibPrev - Previous DIB
// hdib - DIB to RLE
//
// returns
//
// handle to a RLE DIB
//
BOOL FAR PASCAL RleDeltaFrame(
LPBITMAPINFOHEADER lpbiRle, LPBYTE pbRle,
LPBITMAPINFOHEADER lpbiPrev, LPBYTE pbPrev,
LPBITMAPINFOHEADER lpbiDib, LPBYTE pbDib,
int iStart,
int iLen,
long tolTemporal,
long tolSpatial,
int maxRun,
int minJump)
{
LPBITMAPINFOHEADER lpbi;
int biHeight;
UINT cbJump=0;
int dy;
if (!lpbiDib)
return FALSE;
if (maxRun == 0)
maxRun = -1;
if (minJump == 0)
minJump = 4;
//
// Get info on the source and dest dibs
//
lpbi = lpbiDib;
biHeight = (int)lpbi->biHeight;
if (iLen <= 0)
iLen = biHeight;
iLen = min(biHeight-iStart, iLen);
//
// Hey! we only work with 8bpp DIBs if we get otherwise barf.
//
if (lpbi->biBitCount != 8 || lpbi->biCompression != BI_RGB)
return FALSE;
#if 0 // CompressBegin does this..
//
// Set up the table for quick sum of squares calculation (see rle.h)
//
if (!MakeRgbTable(lpbi))
return FALSE;
#endif
//
// lock all the buffers, and start the delta framin'
//
lpbi = lpbiRle;
if (iStart > 0)
pbDib = DibXYN(lpbiDib, pbDib,0,iStart,8);
if (iStart > 0 && lpbiPrev)
pbPrev = DibXYN(lpbiPrev,pbPrev,0,iStart,8);
if (lpbiPrev == NULL)
pbPrev = NULL;
while(iStart > 0)
{
dy = min(iStart,255);
*pbRle++ = RLE_ESCAPE;
*pbRle++ = RLE_JMP;
*pbRle++ = 0;
*pbRle++ = (BYTE)dy;
iStart -= dy;
cbJump += 4;
}
lpbi->biHeight = iLen;
#ifdef _WIN32
DeltaFrameC(
#else
DeltaFrame386(
#endif
lpbi, pbPrev, pbDib, pbRle, maxRun, minJump,
gRgbTol.hpTable, tolTemporal, tolSpatial);
lpbi->biHeight = biHeight;
lpbi->biSizeImage += cbJump; // adjust size to include JUMP!
return TRUE;
}
/* Next is a table that, for each pair of palette entries, helps determine
if two colours are close enough to be merged to a single colour
Let's say the first pixel of a frame is black, and the same pixel in the
next frame is gray. Should you bother painting that gray pixel or let it
stay black because it's close enough? With this table, you have 2 palettes
(one for each of the two frames you are comparing, or possibly two identical
palettes if you are filtering a single DIB) and a table associated with
those palettes. You can index into the table with the colour number of the
pixel in the first frame and the colour number of the pixel in the second
frame. The table value will be a number representing how different those
two colours are.
|Red1 - Red2|^2 + |Green1 - Green2|^2 + |Blue1 - Blue2|^2
is that value (sum of squares of differences). As soon as you start
using this table with a pair of palettes, those hpals are put in this
structure so that you know what pair of palettes the table is built with.
If you change a palette, you need to recompute the table. BUT: you don't
build the table at the beginning, you do it on demand. Initially, the
table is filled with a value of UNCOMPUTED, and as the values are needed,
they are put into the table, so a second call to the CloseEnough routine
with the same colours will exit extremely quickly with no calculations!
Prepare the table for looking up quickly the sum of squares of colours
of two palette entries (possibly in different palettes) */
DWORD NEAR _fastcall RgbCompare(RGBQUAD rgb1, RGBQUAD rgb2)
{
DWORD sum=0;
//
// lets do some magic so the compiler generates "good" code.
//
#define SUMSQ(a,b) \
if (a > b) \
sum += (WORD)(a-b) * (WORD)(a-b); \
else \
sum += (WORD)(b-a) * (WORD)(b-a);
SUMSQ(rgb1.rgbRed, rgb2.rgbRed);
SUMSQ(rgb1.rgbGreen, rgb2.rgbGreen);
SUMSQ(rgb1.rgbBlue, rgb2.rgbBlue);
return sum;
}
BOOL NEAR PASCAL MakeRgbTable(LPBITMAPINFOHEADER lpbi)
{
UINT i, j;
int n=0;
DWORD tol;
if (!lpbi)
return FALSE;
if (lpbi->biClrUsed == 0)
lpbi->biClrUsed = 1 << lpbi->biBitCount;
/* If the palette passed in has a different number of colours than */
/* the one in the table, we obviously need a new table */
if (gRgbTol.hpTable == NULL ||
(int)lpbi->biClrUsed != gRgbTol.ClrUsed ||
_fmemcmp(lpbi+1, gRgbTol.argbq, gRgbTol.ClrUsed * sizeof(RGBQUAD)))
{
if (gRgbTol.hpTable == NULL)
{
gRgbTol.hpTable = (LPVOID)GlobalAllocPtr(GHND|GMEM_SHARE, 256L * 256L * sizeof(DWORD));
if (gRgbTol.hpTable == NULL)
return FALSE;
}
gRgbTol.ClrUsed = (int)lpbi->biClrUsed; // get the actual colours
for (i = 0; i < (UINT)gRgbTol.ClrUsed; i++)
gRgbTol.argbq[i] = ((LPRGBQUAD)(lpbi + 1))[i];
for (i = 0; i < (UINT)gRgbTol.ClrUsed; i++)
{
for (j = 0; j <= i; j++)
{
tol = RgbCompare(gRgbTol.argbq[i], gRgbTol.argbq[j]);
gRgbTol.hpTable[256 * i + j] = tol;
gRgbTol.hpTable[256 * j + i] = tol;
}
}
}
return TRUE;
}
#ifdef _WIN32
// ---- DeltaFrameC --------------------------------------------------------
#define TolLookUp(p, a, b) ( ((LPDWORD)p)[a * 256 + b] )
LPBYTE EncodeFragment(LPBYTE pIn, int len, LPBYTE pOut, LPDWORD pTol, DWORD tolerance, UINT maxrun);
LPBYTE EncodeAbsolute(LPBYTE pbDib, int len, LPBYTE pbRle);
int FindFragmentLength(LPBYTE pIn, LPBYTE pPrev, int len, UINT maxjmp, LPDWORD pTol, DWORD tol, PDWORD prunlen);
// rle format:
// byte 1: 0 - escape
// byte 2: 0 - eol
// byte 2: 1 - eof
// byte 2: 2 - jump x, y (bytes 3, 4)
// byte 2: >2 - absolute run of pixels - byte 2 is length
// byte 1: >0 - repeat solid colour - byte 1 is length
// byte 2 is solid pixel to repeat
// compression - in df.asm for Win16
extern void DeltaFrameC(
LPBITMAPINFOHEADER lpbi,
LPBYTE pbPrev,
LPBYTE pbDib,
LPBYTE pbRle,
UINT MaxRunLength,
UINT MinJumpLength,
LPDWORD TolTable,
DWORD tolTemporal,
DWORD tolSpatial)
{
int WidthBytes = (lpbi->biWidth+3) & (~3);
int x, y;
LPBYTE pbRle_Orig = pbRle;
if ((MaxRunLength == 0) || (MaxRunLength > 255)) {
MaxRunLength = 255;
}
if (pbPrev == NULL) {
// no previous frame, just encode each line spatially
for (y = lpbi->biHeight; y > 0; y--) {
pbRle = EncodeFragment(
pbDib,
lpbi->biWidth,
pbRle,
TolTable,
tolSpatial,
MaxRunLength);
// don't bother to insert an EOL if we are about to insert EOF
if (y > 0) {
* (WORD FAR *)pbRle = RLE_ESCAPE | (RLE_EOL << 8);
pbRle += sizeof(WORD);
}
pbDib += WidthBytes;
}
} else {
int jumpX = 0;
int jumpY = 0;
int frag, runlen;
for (y = 0; y < lpbi->biHeight; y++) {
x = 0;
while (x < lpbi->biWidth) {
// see how much is not the same as the previous frame,
// followed by how much is the same. frag is the length of
// the not-similar fragment; runlen is the length of the
// similar fragment.
frag = FindFragmentLength(
pbDib,
pbPrev,
lpbi->biWidth - x,
MinJumpLength,
TolTable,
tolTemporal,
&runlen
);
if (frag == 0) {
// no fragment, just a jump over the similar pixels.
//add up jumps until we need to output them
jumpX += runlen;
x += runlen;
pbPrev += runlen;
pbDib += runlen;
} else {
// output any saved jumps
if (jumpX < 0) {
// don't jump backwards - eol and jump forwards
*(WORD FAR *)pbRle = RLE_ESCAPE | (RLE_EOL << 8);
pbRle += sizeof(WORD);
// jump is now across to current position,
// and one fewer lines.
jumpX = x;
jumpY--;
}
while (jumpX + jumpY) {
int delta;
* (WORD FAR *)pbRle = RLE_ESCAPE | (RLE_JMP << 8);
pbRle += sizeof(WORD);
// max jump size is 255
delta = min(255, jumpX);
*pbRle++ = (BYTE) delta;
jumpX -= delta;
delta = min(255, jumpY);
*pbRle++ = (BYTE) delta;
jumpY -= delta;
}
// output the different fragment as a combination
// of solid runs and absolute pixels
pbRle = EncodeFragment(
pbDib,
frag,
pbRle,
TolTable,
tolSpatial,
MaxRunLength);
x += frag;
pbDib += frag;
pbPrev += frag;
}
}
// end-of-line
jumpY++;
// advance past DWORD-rounding bytes
pbPrev += (WidthBytes - lpbi->biWidth);
pbDib += (WidthBytes - lpbi->biWidth);
//adjust jumpX
jumpX -= x;
}
}
// end-of-frame
* (WORD FAR *)pbRle = RLE_ESCAPE | (RLE_EOF << 8);
pbRle += sizeof(WORD);
// update lpbi to correct size and format
lpbi->biSizeImage = (DWORD) (pbRle - pbRle_Orig);
lpbi->biCompression = BI_RLE8;
}
//
// encode a sequence of pixels as a mixture of solid runs and absolute
// pixels. write the rle data to pbRle and return pointer to the next
// available rle buffer.
LPBYTE
EncodeFragment(
LPBYTE pbDib,
int width,
LPBYTE pbRle,
LPDWORD TolTable,
DWORD tolerance,
UINT MaxRunLength
)
{
int maxrun, run;
BYTE px;
while (width > 0) {
maxrun = min(255, width);
MaxRunLength = min((int)MaxRunLength, maxrun);
px = *pbDib;
for (run = 0; run < maxrun; run++, pbDib++) {
// the same or similar ? - use tolerance table to compare pixel
// rgb values
// We're allowed a run of 255 if they're exact, but only a run of
// MaxRunLength if they're not exact, only close
if (px == *pbDib)
continue;
if (TolLookUp(TolTable,px,*pbDib) <= tolerance &&
run < (int)MaxRunLength)
continue;
// not close enough - end run
break;
}
// we have found the end of a run of identical pixels
// if the run is one pixel, then we switch into absolute mode.
// however, we cannot encode absolute runs of less than RLE_RUN
// pixels (the runlength code is an escape code and must not coincide
// with RLE_JMP, RLE_EOL and RLE_EOF.
if ((run > 1) || (width < RLE_RUN)) {
// write out run length and colour
* (WORD FAR *)pbRle = run | (px << 8);
pbRle += sizeof(WORD);
width -= run;
} else {
// we have a 'run' of one pixel - back up to point at this.
pbDib--;
// write out an absolute run. now we are in abs mode, we need
// a solid run of at least 4 pixels for it to be worth leaving
// and re-entering abs mode
for (run = 0; run < maxrun; run++) {
// at the end of the fragment ?
if ((maxrun - run) < 4) {
// yes - so no point in looking for a solid run -
// just dump all the remainder as an absolute block
pbRle = EncodeAbsolute(pbDib, maxrun, pbRle);
pbDib += maxrun;
width -= maxrun;
break;
}
px = pbDib[run];
if ( (TolLookUp(TolTable,px,pbDib[run + 1]) <= tolerance) &&
(TolLookUp(TolTable,px,pbDib[run + 2]) <= tolerance) &&
(TolLookUp(TolTable,px,pbDib[run + 3]) <= tolerance)) {
// we have run bytes to encode followed by four
// similar pixels
pbRle = EncodeAbsolute(pbDib, run, pbRle);
pbDib += run;
width -= run;
break;
}
}
}
}
return pbRle;
}
LPBYTE
EncodeAbsolute(LPBYTE pbDib, int runlen, LPBYTE pbRle)
{
if (runlen < RLE_RUN) {
// cannot encode absolute runs of less than RLE_RUN as it
// conflicts with other rle escapes - so encode each pixel
// as a run of 1 of that pixel
int i;
for (i = 0; i < runlen; i++) {
* (WORD FAR *) pbRle = 1 | ((*pbDib++) << 8);
pbRle += sizeof(WORD);
}
return pbRle;
}
// absolute run of > RLE_RUN
* (WORD FAR *)pbRle = RLE_ESCAPE | (runlen << 8);
pbRle += sizeof(WORD);
while (runlen >= 2) {
* (WORD FAR *) pbRle = * (WORD UNALIGNED FAR *)pbDib;
pbRle += sizeof(WORD);
pbDib += sizeof(WORD);
runlen -= 2;
}
// remember to keep word alignment
if (runlen) {
*pbRle++ = *pbDib++;
*pbRle++ = 0;
}
return pbRle;
}
// count how many pixels are not the same as the previous frame, and how
// long is the run of similar pixels after it. We must find at least minjump
// similar pixels before we stop.
int
FindFragmentLength(
LPBYTE pIn,
LPBYTE pPrev,
int len,
UINT minjump,
LPDWORD pTol,
DWORD tol,
PDWORD prunlen
)
{
int x;
int run = 0;
for (x = 0; x < len; x++) {
if ((*pIn == *pPrev) || (TolLookUp(pTol, *pIn, *pPrev) <= tol)) {
run++;
} else {
// have we accumulated a run long enough to be worth
// returning ?
if (run >= (int)minjump) {
*prunlen = run;
return x - run;
} else {
run = 0;
}
}
pIn++;
pPrev++;
}
// end of line - did we find a run ?
if (run < (int) minjump) {
*prunlen = 0;
return len;
} else {
*prunlen = run;
return x - run;
}
}
#endif