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149 lines
3.6 KiB
C
149 lines
3.6 KiB
C
/*
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* The Python Imaging Library.
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* $Id$
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*
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* encoder for PCX data
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*
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* history:
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* 99-02-07 fl created
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*
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* Copyright (c) Fredrik Lundh 1999.
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* Copyright (c) Secret Labs AB 1999.
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*
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* See the README file for information on usage and redistribution.
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*/
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#include "Imaging.h"
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enum { INIT, FETCH, ENCODE };
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/* we're reusing "ystep" to store the last value */
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#define LAST ystep
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int
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ImagingPcxEncode(Imaging im, ImagingCodecState state, UINT8* buf, int bytes)
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{
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UINT8* ptr;
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int this;
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ptr = buf;
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if (!state->state) {
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/* sanity check */
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if (state->xsize <= 0 || state->ysize <= 0) {
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state->errcode = IMAGING_CODEC_END;
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return 0;
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}
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state->bytes = (state->xsize*state->bits + 7) / 8;
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state->state = FETCH;
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}
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for (;;)
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switch (state->state) {
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case FETCH:
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/* get a line of data */
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if (state->y >= state->ysize) {
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state->errcode = IMAGING_CODEC_END;
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return ptr - buf;
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}
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state->shuffle(state->buffer,
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(UINT8*) im->image[state->y + state->yoff] +
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state->xoff * im->pixelsize, state->xsize);
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state->y++;
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state->count = 1;
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state->LAST = state->buffer[0];
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state->x = 1;
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state->state = ENCODE;
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/* fall through */
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case ENCODE:
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/* compress this line */
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/* when we arrive here, "count" contains the number of
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bytes having the value of "LAST" that we've already
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seen */
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while (state->x < state->bytes) {
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if (state->count == 63) {
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/* this run is full; flush it */
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if (bytes < 2)
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return ptr - buf;
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*ptr++ = 0xff;
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*ptr++ = state->LAST;
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bytes -= 2;
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state->count = 0;
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}
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this = state->buffer[state->x];
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if (this == state->LAST) {
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/* extend the current run */
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state->x++;
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state->count++;
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} else {
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/* start a new run */
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if (state->count == 1 && (state->LAST < 0xc0)) {
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if (bytes < 1)
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return ptr - buf;
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*ptr++ = state->LAST;
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bytes--;
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} else {
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if (state->count > 0) {
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if (bytes < 2)
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return ptr - buf;
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*ptr++ = 0xc0 | state->count;
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*ptr++ = state->LAST;
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bytes -= 2;
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}
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}
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state->LAST = this;
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state->count = 1;
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state->x++;
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}
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}
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/* end of line; flush the current run */
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if (state->count == 1 && (state->LAST < 0xc0)) {
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if (bytes < 1)
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return ptr - buf;
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*ptr++ = state->LAST;
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bytes--;
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} else {
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if (state->count > 0) {
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if (bytes < 2)
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return ptr - buf;
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*ptr++ = 0xc0 | state->count;
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*ptr++ = state->LAST;
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bytes -= 2;
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}
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}
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/* read next line */
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state->state = FETCH;
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break;
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}
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}
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