/* * transupp.c * * Copyright (C) 1997, Thomas G. Lane. * This file is part of the Independent JPEG Group's software. * For conditions of distribution and use, see the accompanying README file. * * This file contains image transformation routines and other utility code * used by the jpegtran sample application.  These are NOT part of the core * JPEG library.  But we keep these routines separate from jpegtran.c to * ease the task of maintaining jpegtran-like programs that have other user * interfaces. *//* Although this file really shouldn't have access to the library internals, * it's helpful to let it call jround_up() and jcopy_block_row(). */#define JPEG_INTERNALS#include "jinclude.h"#include "jpeglib.h"#include "transupp.h"   /* My own external interface */#if TRANSFORMS_SUPPORTED/* * Lossless image transformation routines.  These routines work on DCT * coefficient arrays and thus do not require any lossy decompression * or recompression of the image. * Thanks to Guido Vollbeding for the initial design and code of this feature. * * Horizontal flipping is done in-place, using a single top-to-bottom * pass through the virtual source array.  It will thus be much the * fastest option for images larger than main memory. * * The other routines require a set of destination virtual arrays, so they * need twice as much memory as jpegtran normally does.  The destination * arrays are always written in normal scan order (top to bottom) because * the virtual array manager expects this.  The source arrays will be scanned * in the corresponding order, which means multiple passes through the source * arrays for most of the transforms.  That could result in much thrashing * if the image is larger than main memory. * * Some notes about the operating environment of the individual transform * routines: * 1. Both the source and destination virtual arrays are allocated from the *    source JPEG object, and therefore should be manipulated by calling the *    source's memory manager. * 2. The destination's component count should be used.  It may be smaller *    than the source's when forcing to grayscale. * 3. Likewise the destination's sampling factors should be used.  When *    forcing to grayscale the destination's sampling factors will be all 1, *    and we may as well take that as the effective iMCU size. * 4. When "trim" is in effect, the destination's dimensions will be the *    trimmed values but the source's will be untrimmed. * 5. All the routines assume that the source and destination buffers are *    padded out to a full iMCU boundary.  This is true, although for the *    source buffer it is an undocumented property of jdcoefct.c. * Notes 2,3,4 boil down to this: generally we should use the destination's * dimensions and ignore the source's. */LOCAL(void)do_flip_h (j_decompress_ptr srcinfo, j_compress_ptr dstinfo,     jvirt_barray_ptr *src_coef_arrays)/* Horizontal flip; done in-place, so no separate dest array is required */{  JDIMENSION MCU_cols, comp_width, blk_x, blk_y;  int ci, k, offset_y;  JBLOCKARRAY buffer;  JCOEFPTR ptr1, ptr2;  JCOEF temp1, temp2;  jpeg_component_info *compptr;  /* Horizontal mirroring of DCT blocks is accomplished by swapping   * pairs of blocks in-place.  Within a DCT block, we perform horizontal   * mirroring by changing the signs of odd-numbered columns.   * Partial iMCUs at the right edge are left untouched.   */  MCU_cols = dstinfo->image_width / (dstinfo->max_h_samp_factor * DCTSIZE);  for (ci = 0; ci < dstinfo->num_components; ci++) {    compptr = dstinfo->comp_info + ci;    comp_width = MCU_cols * compptr->h_samp_factor;    for (blk_y = 0; blk_y < compptr->height_in_blocks;   blk_y += compptr->v_samp_factor) {      buffer = (*srcinfo->mem->access_virt_barray)  ((j_common_ptr) srcinfo, src_coef_arrays[ci], blk_y,   (JDIMENSION) compptr->v_samp_factor, TRUE);      for (offset_y = 0; offset_y < compptr->v_samp_factor; offset_y++) {  for (blk_x = 0; blk_x * 2 < comp_width; blk_x++) {    ptr1 = buffer[offset_y][blk_x];    ptr2 = buffer[offset_y][comp_width - blk_x - 1];    /* this unrolled loop doesn't need to know which row it's on... */    for (k = 0; k < DCTSIZE2; k += 2) {      temp1 = *ptr1;  /* swap even column */      temp2 = *ptr2;      *ptr1++ = temp2;      *ptr2++ = temp1;      temp1 = *ptr1;  /* swap odd column with sign change */      temp2 = *ptr2;      *ptr1++ = -temp2;      *ptr2++ = -temp1;    }  }      }    }  }}LOCAL(void)do_flip_v (j_decompress_ptr srcinfo, j_compress_ptr dstinfo,     jvirt_barray_ptr *src_coef_arrays,     jvirt_barray_ptr *dst_coef_arrays)/* Vertical flip */{  JDIMENSION MCU_rows, comp_height, dst_blk_x, dst_blk_y;  int ci, i, j, offset_y;  JBLOCKARRAY src_buffer, dst_buffer;  JBLOCKROW src_row_ptr, dst_row_ptr;  JCOEFPTR src_ptr, dst_ptr;  jpeg_component_info *compptr;  /* We output into a separate array because we can't touch different   * rows of the source virtual array simultaneously.  Otherwise, this   * is a pretty straightforward analog of horizontal flip.   * Within a DCT block, vertical mirroring is done by changing the signs   * of odd-numbered rows.   * Partial iMCUs at the bottom edge are copied verbatim.   */  MCU_rows = dstinfo->image_height / (dstinfo->max_v_samp_factor * DCTSIZE);  for (ci = 0; ci < dstinfo->num_components; ci++) {    compptr = dstinfo->comp_info + ci;    comp_height = MCU_rows * compptr->v_samp_factor;    for (dst_blk_y = 0; dst_blk_y < compptr->height_in_blocks;   dst_blk_y += compptr->v_samp_factor) {      dst_buffer = (*srcinfo->mem->access_virt_barray)  ((j_common_ptr) srcinfo, dst_coef_arrays[ci], dst_blk_y,   (JDIMENSION) compptr->v_samp_factor, TRUE);      if (dst_blk_y < comp_height) {  /* Row is within the mirrorable area. */  src_buffer = (*srcinfo->mem->access_virt_barray)    ((j_common_ptr) srcinfo, src_coef_arrays[ci],     comp_height - dst_blk_y - (JDIMENSION) compptr->v_samp_factor,     (JDIMENSION) compptr->v_samp_factor, FALSE);      } else {  /* Bottom-edge blocks will be copied verbatim. */  src_buffer = (*srcinfo->mem->access_virt_barray)    ((j_common_ptr) srcinfo, src_coef_arrays[ci], dst_blk_y,     (JDIMENSION) compptr->v_samp_factor, FALSE);      }      for (offset_y = 0; offset_y < compptr->v_samp_factor; offset_y++) {  if (dst_blk_y < comp_height) {    /* Row is within the mirrorable area. */    dst_row_ptr = dst_buffer[offset_y];    src_row_ptr = src_buffer[compptr->v_samp_factor - offset_y - 1];    for (dst_blk_x = 0; dst_blk_x < compptr->width_in_blocks;         dst_blk_x++) {      dst_ptr = dst_row_ptr[dst_blk_x];      src_ptr = src_row_ptr[dst_blk_x];      for (i = 0; i < DCTSIZE; i += 2) {        /* copy even row */        for (j = 0; j < DCTSIZE; j++)    *dst_ptr++ = *src_ptr++;        /* copy odd row with sign change */        for (j = 0; j < DCTSIZE; j++)    *dst_ptr++ = - *src_ptr++;      }    }  } else {    /* Just copy row verbatim. */    jcopy_block_row(src_buffer[offset_y], dst_buffer[offset_y],        compptr->width_in_blocks);  }      }    }  }}LOCAL(void)do_transpose (j_decompress_ptr srcinfo, j_compress_ptr dstinfo,        jvirt_barray_ptr *src_coef_arrays,        jvirt_barray_ptr *dst_coef_arrays)/* Transpose source into destination */{  JDIMENSION dst_blk_x, dst_blk_y;  int ci, i, j, offset_x, offset_y;  JBLOCKARRAY src_buffer, dst_buffer;  JCOEFPTR src_ptr, dst_ptr;  jpeg_component_info *compptr;  /* Transposing pixels within a block just requires transposing the   * DCT coefficients.   * Partial iMCUs at the edges require no special treatment; we simply   * process all the available DCT blocks for every component.   */  for (ci = 0; ci < dstinfo->num_components; ci++) {    compptr = dstinfo->comp_info + ci;    for (dst_blk_y = 0; dst_blk_y < compptr->height_in_blocks;   dst_blk_y += compptr->v_samp_factor) {      dst_buffer = (*srcinfo->mem->access_virt_barray)  ((j_common_ptr) srcinfo, dst_coef_arrays[ci], dst_blk_y,   (JDIMENSION) compptr->v_samp_factor, TRUE);      for (offset_y = 0; offset_y < compptr->v_samp_factor; offset_y++) {  for (dst_blk_x = 0; dst_blk_x < compptr->width_in_blocks;       dst_blk_x += compptr->h_samp_factor) {    src_buffer = (*srcinfo->mem->access_virt_barray)      ((j_common_ptr) srcinfo, src_coef_arrays[ci], dst_blk_x,       (JDIMENSION) compptr->h_samp_factor, FALSE);    for (offset_x = 0; offset_x < compptr->h_samp_factor; offset_x++) {      src_ptr = src_buffer[offset_x][dst_blk_y + offset_y];      dst_ptr = dst_buffer[offset_y][dst_blk_x + offset_x];      for (i = 0; i < DCTSIZE; i++)        for (j = 0; j < DCTSIZE; j++)    dst_ptr[j*DCTSIZE+i] = src_ptr[i*DCTSIZE+j];    }  }      }    }  }}LOCAL(void)do_rot_90 (j_decompress_ptr srcinfo, j_compress_ptr dstinfo,     jvirt_barray_ptr *src_coef_arrays,     jvirt_barray_ptr *dst_coef_arrays)/* 90 degree rotation is equivalent to *   1. Transposing the image; *   2. Horizontal mirroring. * These two steps are merged into a single processing routine. */{  JDIMENSION MCU_cols, comp_width, dst_blk_x, dst_blk_y;  int ci, i, j, offset_x, offset_y;  JBLOCKARRAY src_buffer, dst_buffer;  JCOEFPTR src_ptr, dst_ptr;  jpeg_component_info *compptr;  /* Because of the horizontal mirror step, we can't process partial iMCUs   * at the (output) right edge properly.  They just get transposed and   * not mirrored.   */  MCU_cols = dstinfo->image_width / (dstinfo->max_h_samp_factor * DCTSIZE);  for (ci = 0; ci < dstinfo->num_components; ci++) {    compptr = dstinfo->comp_info + ci;    comp_width = MCU_cols * compptr->h_samp_factor;    for (dst_blk_y = 0; dst_blk_y < compptr->height_in_blocks;   dst_blk_y += compptr->v_samp_factor) {      dst_buffer = (*srcinfo->mem->access_virt_barray)  ((j_common_ptr) srcinfo, dst_coef_arrays[ci], dst_blk_y,   (JDIMENSION) compptr->v_samp_factor, TRUE);      for (offset_y = 0; offset_y < compptr->v_samp_factor; offset_y++) {  for (dst_blk_x = 0; dst_blk_x < compptr->width_in_blocks;       dst_blk_x += compptr->h_samp_factor) {    src_buffer = (*srcinfo->mem->access_virt_barray)      ((j_common_ptr) srcinfo, src_coef_arrays[ci], dst_blk_x,       (JDIMENSION) compptr->h_samp_factor, FALSE);    for (offset_x = 0; offset_x < compptr->h_samp_factor; offset_x++) {      src_ptr = src_buffer[offset_x][dst_blk_y + offset_y];      if (dst_blk_x < comp_width) {        /* Block is within the mirrorable area. */        dst_ptr = dst_buffer[offset_y]    [comp_width - dst_blk_x - offset_x - 1];        for (i = 0; i < DCTSIZE; i++) {    for (j = 0; j < DCTSIZE; j++)      dst_ptr[j*DCTSIZE+i] = src_ptr[i*DCTSIZE+j];    i++;    for (j = 0; j < DCTSIZE; j++)      dst_ptr[j*DCTSIZE+i] = -src_ptr[i*DCTSIZE+j];        }      } else {        /* Edge blocks are transposed but not mirrored. */        dst_ptr = dst_buffer[offset_y][dst_blk_x + offset_x];        for (i = 0; i < DCTSIZE; i++)    for (j = 0; j < DCTSIZE; j++)      dst_ptr[j*DCTSIZE+i] = src_ptr[i*DCTSIZE+j];      }    }  }      }    }  }}LOCAL(void)do_rot_270 (j_decompress_ptr srcinfo, j_compress_ptr dstinfo,      jvirt_barray_ptr *src_coef_arrays,      jvirt_barray_ptr *dst_coef_arrays)/* 270 degree rotation is equivalent to *   1. Horizontal mirroring; *   2. Transposing the image. * These two steps are merged into a single processing routine. */{  JDIMENSION MCU_rows, comp_height, dst_blk_x, dst_blk_y;  int ci, i, j, offset_x, offset_y;  JBLOCKARRAY src_buffer, dst_buffer;  JCOEFPTR src_ptr, dst_ptr;  jpeg_component_info *compptr;  /* Because of the horizontal mirror step, we can't process partial iMCUs   * at the (output) bottom edge properly.  They just get transposed and