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+//
+// Copyright (C) 2002 RealVNC Ltd. All Rights Reserved.
+//
+// This is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 2 of the License, or
+// (at your option) any later version.
+//
+// This software is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this software; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
+// USA.
+
+//
+// zrleEncode.h - zrle encoding function.
+//
+// Before including this file, you must define a number of CPP macros.
+//
+// BPP should be 8, 16 or 32 depending on the bits per pixel.
+// GET_IMAGE_INTO_BUF should be some code which gets a rectangle of pixel data
+// into the given buffer. EXTRA_ARGS can be defined to pass any other
+// arguments needed by GET_IMAGE_INTO_BUF.
+//
+// Note that the buf argument to ZRLE_ENCODE needs to be at least one pixel
+// bigger than the largest tile of pixel data, since the ZRLE encoding
+// algorithm writes to the position one past the end of the pixel data.
+//
+
+#include <rdr/OutStream.h>
+#include <assert.h>
+
+using namespace rdr;
+
+/* __RFB_CONCAT2 concatenates its two arguments. __RFB_CONCAT2E does the same
+ but also expands its arguments if they are macros */
+
+#ifndef __RFB_CONCAT2E
+#define __RFB_CONCAT2(a,b) a##b
+#define __RFB_CONCAT2E(a,b) __RFB_CONCAT2(a,b)
+#endif
+
+#ifdef CPIXEL
+#define PIXEL_T __RFB_CONCAT2E(rdr::U,BPP)
+#define WRITE_PIXEL __RFB_CONCAT2E(writeOpaque,CPIXEL)
+#define ZRLE_ENCODE __RFB_CONCAT2E(zrleEncode,CPIXEL)
+#define ZRLE_ENCODE_TILE __RFB_CONCAT2E(zrleEncodeTile,CPIXEL)
+#define BPPOUT 24
+#else
+#define PIXEL_T __RFB_CONCAT2E(rdr::U,BPP)
+#define WRITE_PIXEL __RFB_CONCAT2E(writeOpaque,BPP)
+#define ZRLE_ENCODE __RFB_CONCAT2E(zrleEncode,BPP)
+#define ZRLE_ENCODE_TILE __RFB_CONCAT2E(zrleEncodeTile,BPP)
+#define BPPOUT BPP
+#endif
+
+#ifndef ZRLE_ONCE
+#define ZRLE_ONCE
+static const int bitsPerPackedPixel[] = {
+ 0, 1, 2, 2, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4
+};
+
+// The PaletteHelper class helps us build up the palette from pixel data by
+// storing a reverse index using a simple hash-table
+
+class PaletteHelper {
+public:
+ enum { MAX_SIZE = 127 };
+
+ PaletteHelper()
+ {
+ memset(index, 255, sizeof(index));
+ size = 0;
+ }
+
+ inline int hash(rdr::U32 pix)
+ {
+ return (pix ^ (pix >> 17)) & 4095;
+ }
+
+ inline void insert(rdr::U32 pix)
+ {
+ if (size < MAX_SIZE) {
+ int i = hash(pix);
+ while (index[i] != 255 && key[i] != pix)
+ i++;
+ if (index[i] != 255) return;
+
+ index[i] = size;
+ key[i] = pix;
+ palette[size] = pix;
+ }
+ size++;
+ }
+
+ inline int lookup(rdr::U32 pix)
+ {
+ assert(size <= MAX_SIZE);
+ int i = hash(pix);
+ while (index[i] != 255 && key[i] != pix)
+ i++;
+ if (index[i] != 255) return index[i];
+ return -1;
+ }
+
+ rdr::U32 palette[MAX_SIZE];
+ rdr::U8 index[4096+MAX_SIZE];
+ rdr::U32 key[4096+MAX_SIZE];
+ int size;
+};
+#endif
+
+void ZRLE_ENCODE_TILE (PIXEL_T* data, int w, int h, rdr::OutStream* os);
+
+void ZRLE_ENCODE (int x, int y, int w, int h, rdr::OutStream* os,
+ rdr::ZlibOutStream* zos, void* buf
+ EXTRA_ARGS
+ )
+{
+ zos->setUnderlying(os);
+
+ for (int ty = y; ty < y+h; ty += rfbZRLETileHeight) {
+ int th = rfbZRLETileHeight;
+ if (th > y+h-ty) th = y+h-ty;
+ for (int tx = x; tx < x+w; tx += rfbZRLETileWidth) {
+ int tw = rfbZRLETileWidth;
+ if (tw > x+w-tx) tw = x+w-tx;
+
+ GET_IMAGE_INTO_BUF(tx,ty,tw,th,buf);
+
+ ZRLE_ENCODE_TILE((PIXEL_T*)buf, tw, th, zos);
+ }
+ }
+ zos->flush();
+}
+
+
+void ZRLE_ENCODE_TILE (PIXEL_T* data, int w, int h, rdr::OutStream* os)
+{
+ // First find the palette and the number of runs
+
+ PaletteHelper ph;
+
+ int runs = 0;
+ int singlePixels = 0;
+
+ PIXEL_T* ptr = data;
+ PIXEL_T* end = ptr + h * w;
+ *end = ~*(end-1); // one past the end is different so the while loop ends
+
+ while (ptr < end) {
+ PIXEL_T pix = *ptr;
+ if (*++ptr != pix) {
+ singlePixels++;
+ } else {
+ while (*++ptr == pix) ;
+ runs++;
+ }
+ ph.insert(pix);
+ }
+
+ //fprintf(stderr,"runs %d, single pixels %d, paletteSize %d\n",
+ // runs, singlePixels, ph.size);
+
+ // Solid tile is a special case
+
+ if (ph.size == 1) {
+ os->writeU8(1);
+ os->WRITE_PIXEL(ph.palette[0]);
+ return;
+ }
+
+ // Try to work out whether to use RLE and/or a palette. We do this by
+ // estimating the number of bytes which will be generated and picking the
+ // method which results in the fewest bytes. Of course this may not result
+ // in the fewest bytes after compression...
+
+ bool useRle = false;
+ bool usePalette = false;
+
+ int estimatedBytes = w * h * (BPPOUT/8); // start assuming raw
+
+ int plainRleBytes = ((BPPOUT/8)+1) * (runs + singlePixels);
+
+ if (plainRleBytes < estimatedBytes) {
+ useRle = true;
+ estimatedBytes = plainRleBytes;
+ }
+
+ if (ph.size < 128) {
+ int paletteRleBytes = (BPPOUT/8) * ph.size + 2 * runs + singlePixels;
+
+ if (paletteRleBytes < estimatedBytes) {
+ useRle = true;
+ usePalette = true;
+ estimatedBytes = paletteRleBytes;
+ }
+
+ if (ph.size < 17) {
+ int packedBytes = ((BPPOUT/8) * ph.size +
+ w * h * bitsPerPackedPixel[ph.size-1] / 8);
+
+ if (packedBytes < estimatedBytes) {
+ useRle = false;
+ usePalette = true;
+ estimatedBytes = packedBytes;
+ }
+ }
+ }
+
+ if (!usePalette) ph.size = 0;
+
+ os->writeU8((useRle ? 128 : 0) | ph.size);
+
+ for (int i = 0; i < ph.size; i++) {
+ os->WRITE_PIXEL(ph.palette[i]);
+ }
+
+ if (useRle) {
+
+ PIXEL_T* ptr = data;
+ PIXEL_T* end = ptr + w * h;
+ PIXEL_T* runStart;
+ PIXEL_T pix;
+ while (ptr < end) {
+ runStart = ptr;
+ pix = *ptr++;
+ while (*ptr == pix && ptr < end)
+ ptr++;
+ int len = ptr - runStart;
+ if (len <= 2 && usePalette) {
+ int index = ph.lookup(pix);
+ if (len == 2)
+ os->writeU8(index);
+ os->writeU8(index);
+ continue;
+ }
+ if (usePalette) {
+ int index = ph.lookup(pix);
+ os->writeU8(index | 128);
+ } else {
+ os->WRITE_PIXEL(pix);
+ }
+ len -= 1;
+ while (len >= 255) {
+ os->writeU8(255);
+ len -= 255;
+ }
+ os->writeU8(len);
+ }
+
+ } else {
+
+ // no RLE
+
+ if (usePalette) {
+
+ // packed pixels
+
+ assert (ph.size < 17);
+
+ int bppp = bitsPerPackedPixel[ph.size-1];
+
+ PIXEL_T* ptr = data;
+
+ for (int i = 0; i < h; i++) {
+ U8 nbits = 0;
+ U8 byte = 0;
+
+ PIXEL_T* eol = ptr + w;
+
+ while (ptr < eol) {
+ PIXEL_T pix = *ptr++;
+ U8 index = ph.lookup(pix);
+ byte = (byte << bppp) | index;
+ nbits += bppp;
+ if (nbits >= 8) {
+ os->writeU8(byte);
+ nbits = 0;
+ }
+ }
+ if (nbits > 0) {
+ byte <<= 8 - nbits;
+ os->writeU8(byte);
+ }
+ }
+ } else {
+
+ // raw
+
+#ifdef CPIXEL
+ for (PIXEL_T* ptr = data; ptr < data+w*h; ptr++) {
+ os->WRITE_PIXEL(*ptr);
+ }
+#else
+ os->writeBytes(data, w*h*(BPP/8));
+#endif
+ }
+ }
+}
+
+#undef PIXEL_T
+#undef WRITE_PIXEL
+#undef ZRLE_ENCODE
+#undef ZRLE_ENCODE_TILE
+#undef BPPOUT
generated by cgit v1.2.1 (git 2.18.0) at 2024-04-26 09:54:47 +0000