Imported Upstream version 1.7.0upstream/1.7.0

1 files changed, 1597 insertions, 0 deletions

diff --git a/jpeg/transupp.c b/jpeg/transupp.c
new file mode 100644
index 0000000..016f383
--- /dev/null
+++ b/jpeg/transupp.c
@@ -0,0 +1,1597 @@
+/*
+ * transupp.c
+ *
+ * Copyright (C) 1997-2011, Thomas G. Lane, Guido Vollbeding.
+ * 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 */
+#include <ctype.h>		/* to declare isdigit() */
+
+
+#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,
+ * and to Ben Jackson for introducing the cropping 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.
+ *
+ * If cropping or trimming is involved, the destination arrays may be smaller
+ * than the source arrays.  Note it is not possible to do horizontal flip
+ * in-place when a nonzero Y crop offset is specified, since we'd have to move
+ * data from one block row to another but the virtual array manager doesn't
+ * guarantee we can touch more than one row at a time.  So in that case,
+ * we have to use a separate destination array.
+ *
+ * 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. When "crop" is in effect, the destination's dimensions will be the
+ *    cropped values but the source's will be uncropped.  Each transform
+ *    routine is responsible for picking up source data starting at the
+ *    correct X and Y offset for the crop region.  (The X and Y offsets
+ *    passed to the transform routines are measured in iMCU blocks of the
+ *    destination.)
+ * 6. 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.
+ */
+
+
+LOCAL(void)
+do_crop (j_decompress_ptr srcinfo, j_compress_ptr dstinfo,
+	 JDIMENSION x_crop_offset, JDIMENSION y_crop_offset,
+	 jvirt_barray_ptr *src_coef_arrays,
+	 jvirt_barray_ptr *dst_coef_arrays)
+/* Crop.  This is only used when no rotate/flip is requested with the crop. */
+{
+  JDIMENSION dst_blk_y, x_crop_blocks, y_crop_blocks;
+  int ci, offset_y;
+  JBLOCKARRAY src_buffer, dst_buffer;
+  jpeg_component_info *compptr;
+
+  /* We simply have to copy the right amount of data (the destination's
+   * image size) starting at the given X and Y offsets in the source.
+   */
+  for (ci = 0; ci < dstinfo->num_components; ci++) {
+    compptr = dstinfo->comp_info + ci;
+    x_crop_blocks = x_crop_offset * compptr->h_samp_factor;
+    y_crop_blocks = y_crop_offset * 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);
+      src_buffer = (*srcinfo->mem->access_virt_barray)
+	((j_common_ptr) srcinfo, src_coef_arrays[ci],
+	 dst_blk_y + y_crop_blocks,
+	 (JDIMENSION) compptr->v_samp_factor, FALSE);
+      for (offset_y = 0; offset_y < compptr->v_samp_factor; offset_y++) {
+	jcopy_block_row(src_buffer[offset_y] + x_crop_blocks,
+			dst_buffer[offset_y],
+			compptr->width_in_blocks);
+      }
+    }
+  }
+}
+
+
+LOCAL(void)
+do_flip_h_no_crop (j_decompress_ptr srcinfo, j_compress_ptr dstinfo,
+		   JDIMENSION x_crop_offset,
+		   jvirt_barray_ptr *src_coef_arrays)
+/* Horizontal flip; done in-place, so no separate dest array is required.
+ * NB: this only works when y_crop_offset is zero.
+ */
+{
+  JDIMENSION MCU_cols, comp_width, blk_x, blk_y, x_crop_blocks;
+  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 = srcinfo->output_width /
+    (dstinfo->max_h_samp_factor * dstinfo->min_DCT_h_scaled_size);
+
+  for (ci = 0; ci < dstinfo->num_components; ci++) {
+    compptr = dstinfo->comp_info + ci;
+    comp_width = MCU_cols * compptr->h_samp_factor;
+    x_crop_blocks = x_crop_offset * 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++) {
+	/* Do the mirroring */
+	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;
+	  }
+	}
+	if (x_crop_blocks > 0) {
+	  /* Now left-justify the portion of the data to be kept.
+	   * We can't use a single jcopy_block_row() call because that routine
+	   * depends on memcpy(), whose behavior is unspecified for overlapping
+	   * source and destination areas.  Sigh.
+	   */
+	  for (blk_x = 0; blk_x < compptr->width_in_blocks; blk_x++) {
+	    jcopy_block_row(buffer[offset_y] + blk_x + x_crop_blocks,
+			    buffer[offset_y] + blk_x,
+			    (JDIMENSION) 1);
+	  }
+	}
+      }
+    }
+  }
+}
+
+
+LOCAL(void)
+do_flip_h (j_decompress_ptr srcinfo, j_compress_ptr dstinfo,
+	   JDIMENSION x_crop_offset, JDIMENSION y_crop_offset,
+	   jvirt_barray_ptr *src_coef_arrays,
+	   jvirt_barray_ptr *dst_coef_arrays)
+/* Horizontal flip in general cropping case */
+{
+  JDIMENSION MCU_cols, comp_width, dst_blk_x, dst_blk_y;
+  JDIMENSION x_crop_blocks, y_crop_blocks;
+  int ci, k, offset_y;
+  JBLOCKARRAY src_buffer, dst_buffer;
+  JBLOCKROW src_row_ptr, dst_row_ptr;
+  JCOEFPTR src_ptr, dst_ptr;
+  jpeg_component_info *compptr;
+
+  /* Here we must output into a separate array because we can't touch
+   * different rows of a single virtual array simultaneously.  Otherwise,
+   * this is essentially the same as the routine above.
+   */
+  MCU_cols = srcinfo->output_width /
+    (dstinfo->max_h_samp_factor * dstinfo->min_DCT_h_scaled_size);
+
+  for (ci = 0; ci < dstinfo->num_components; ci++) {
+    compptr = dstinfo->comp_info + ci;
+    comp_width = MCU_cols * compptr->h_samp_factor;
+    x_crop_blocks = x_crop_offset * compptr->h_samp_factor;
+    y_crop_blocks = y_crop_offset * 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);
+      src_buffer = (*srcinfo->mem->access_virt_barray)
+	((j_common_ptr) srcinfo, src_coef_arrays[ci],
+	 dst_blk_y + y_crop_blocks,
+	 (JDIMENSION) compptr->v_samp_factor, FALSE);
+      for (offset_y = 0; offset_y < compptr->v_samp_factor; offset_y++) {
+	dst_row_ptr = dst_buffer[offset_y];
+	src_row_ptr = src_buffer[offset_y];
+	for (dst_blk_x = 0; dst_blk_x < compptr->width_in_blocks; dst_blk_x++) {
+	  if (x_crop_blocks + dst_blk_x < comp_width) {
+	    /* Do the mirrorable blocks */
+	    dst_ptr = dst_row_ptr[dst_blk_x];
+	    src_ptr = src_row_ptr[comp_width - x_crop_blocks - dst_blk_x - 1];
+	    /* this unrolled loop doesn't need to know which row it's on... */
+	    for (k = 0; k < DCTSIZE2; k += 2) {
+	      *dst_ptr++ = *src_ptr++;	 /* copy even column */
+	      *dst_ptr++ = - *src_ptr++; /* copy odd column with sign change */
+	    }
+	  } else {
+	    /* Copy last partial block(s) verbatim */
+	    jcopy_block_row(src_row_ptr + dst_blk_x + x_crop_blocks,
+			    dst_row_ptr + dst_blk_x,
+			    (JDIMENSION) 1);
+	  }
+	}
+      }
+    }
+  }
+}
+
+
+LOCAL(void)
+do_flip_v (j_decompress_ptr srcinfo, j_compress_ptr dstinfo,
+	   JDIMENSION x_crop_offset, JDIMENSION y_crop_offset,
+	   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;
+  JDIMENSION x_crop_blocks, y_crop_blocks;
+  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 = srcinfo->output_height /
+    (dstinfo->max_v_samp_factor * dstinfo->min_DCT_v_scaled_size);
+
+  for (ci = 0; ci < dstinfo->num_components; ci++) {
+    compptr = dstinfo->comp_info + ci;
+    comp_height = MCU_rows * compptr->v_samp_factor;
+    x_crop_blocks = x_crop_offset * compptr->h_samp_factor;
+    y_crop_blocks = y_crop_offset * 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 (y_crop_blocks + 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 - y_crop_blocks - 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 + y_crop_blocks,
+	   (JDIMENSION) compptr->v_samp_factor, FALSE);
+      }
+      for (offset_y = 0; offset_y < compptr->v_samp_factor; offset_y++) {
+	if (y_crop_blocks + 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];
+	  src_row_ptr += x_crop_blocks;
+	  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] + x_crop_blocks,
+			  dst_buffer[offset_y],
+			  compptr->width_in_blocks);
+	}
+      }
+    }
+  }
+}
+
+
+LOCAL(void)
+do_transpose (j_decompress_ptr srcinfo, j_compress_ptr dstinfo,
+	      JDIMENSION x_crop_offset, JDIMENSION y_crop_offset,
+	      jvirt_barray_ptr *src_coef_arrays,
+	      jvirt_barray_ptr *dst_coef_arrays)
+/* Transpose source into destination */
+{
+  JDIMENSION dst_blk_x, dst_blk_y, x_crop_blocks, y_crop_blocks;
+  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;
+    x_crop_blocks = x_crop_offset * compptr->h_samp_factor;
+    y_crop_blocks = y_crop_offset * 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);
+      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 + x_crop_blocks,
+	     (JDIMENSION) compptr->h_samp_factor, FALSE);
+	  for (offset_x = 0; offset_x < compptr->h_samp_factor; offset_x++) {
+	    dst_ptr = dst_buffer[offset_y][dst_blk_x + offset_x];
+	    src_ptr = src_buffer[offset_x][dst_blk_y + offset_y + y_crop_blocks];
+	    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,
+	   JDIMENSION x_crop_offset, JDIMENSION y_crop_offset,
+	   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;
+  JDIMENSION x_crop_blocks, y_crop_blocks;
+  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 = srcinfo->output_height /
+    (dstinfo->max_h_samp_factor * dstinfo->min_DCT_h_scaled_size);
+
+  for (ci = 0; ci < dstinfo->num_components; ci++) {
+    compptr = dstinfo->comp_info + ci;
+    comp_width = MCU_cols * compptr->h_samp_factor;
+    x_crop_blocks = x_crop_offset * compptr->h_samp_factor;
+    y_crop_blocks = y_crop_offset * 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);
+      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) {
+	  if (x_crop_blocks + dst_blk_x < comp_width) {
+	    /* Block is within the mirrorable area. */
+	    src_buffer = (*srcinfo->mem->access_virt_barray)
+	      ((j_common_ptr) srcinfo, src_coef_arrays[ci],
+	       comp_width - x_crop_blocks - dst_blk_x -
+	       (JDIMENSION) compptr->h_samp_factor,
+	       (JDIMENSION) compptr->h_samp_factor, FALSE);
+	  } else {
+	    /* Edge blocks are transposed but not mirrored. */
+	    src_buffer = (*srcinfo->mem->access_virt_barray)
+	      ((j_common_ptr) srcinfo, src_coef_arrays[ci],
+	       dst_blk_x + x_crop_blocks,
+	       (JDIMENSION) compptr->h_samp_factor, FALSE);
+	  }
+	  for (offset_x = 0; offset_x < compptr->h_samp_factor; offset_x++) {
+	    dst_ptr = dst_buffer[offset_y][dst_blk_x + offset_x];
+	    if (x_crop_blocks + dst_blk_x < comp_width) {
+	      /* Block is within the mirrorable area. */
+	      src_ptr = src_buffer[compptr->h_samp_factor - offset_x - 1]
+		[dst_blk_y + offset_y + y_crop_blocks];
+	      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. */
+	      src_ptr = src_buffer[offset_x]
+		[dst_blk_y + offset_y + y_crop_blocks];
+	      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,
+	    JDIMENSION x_crop_offset, JDIMENSION y_crop_offset,
+	    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;
+  JDIMENSION x_crop_blocks, y_crop_blocks;
+  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
+   * not mirrored.
+   */
+  MCU_rows = srcinfo->output_width /
+    (dstinfo->max_v_samp_factor * dstinfo->min_DCT_v_scaled_size);
+
+  for (ci = 0; ci < dstinfo->num_components; ci++) {
+    compptr = dstinfo->comp_info + ci;
+    comp_height = MCU_rows * compptr->v_samp_factor;
+    x_crop_blocks = x_crop_offset * compptr->h_samp_factor;
+    y_crop_blocks = y_crop_offset * 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);
+      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 + x_crop_blocks,
+	     (JDIMENSION) compptr->h_samp_factor, FALSE);
+	  for (offset_x = 0; offset_x < compptr->h_samp_factor; offset_x++) {
+	    dst_ptr = dst_buffer[offset_y][dst_blk_x + offset_x];
+	    if (y_crop_blocks + dst_blk_y < comp_height) {
+	      /* Block is within the mirrorable area. */
+	      src_ptr = src_buffer[offset_x]
+		[comp_height - y_crop_blocks - dst_blk_y - offset_y - 1];
+	      for (i = 0; i < DCTSIZE; i++) {
+		for (j = 0; j < DCTSIZE; j++) {
+		  dst_ptr[j*DCTSIZE+i] = src_ptr[i*DCTSIZE+j];
+		  j++;
+		  dst_ptr[j*DCTSIZE+i] = -src_ptr[i*DCTSIZE+j];
+		}
+	      }
+	    } else {
+	      /* Edge blocks are transposed but not mirrored. */
+	      src_ptr = src_buffer[offset_x]
+		[dst_blk_y + offset_y + y_crop_blocks];
+	      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_180 (j_decompress_ptr srcinfo, j_compress_ptr dstinfo,
+	    JDIMENSION x_crop_offset, JDIMENSION y_crop_offset,
+	    jvirt_barray_ptr *src_coef_arrays,
+	    jvirt_barray_ptr *dst_coef_arrays)
+/* 180 degree rotation is equivalent to
+ *   1. Vertical mirroring;
+ *   2. Horizontal mirroring.
+ * These two steps are merged into a single processing routine.
+ */
+{
+  JDIMENSION MCU_cols, MCU_rows, comp_width, comp_height, dst_blk_x, dst_blk_y;
+  JDIMENSION x_crop_blocks, y_crop_blocks;
+  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;
+
+  MCU_cols = srcinfo->output_width /
+    (dstinfo->max_h_samp_factor * dstinfo->min_DCT_h_scaled_size);
+  MCU_rows = srcinfo->output_height /
+    (dstinfo->max_v_samp_factor * dstinfo->min_DCT_v_scaled_size);
+
+  for (ci = 0; ci < dstinfo->num_components; ci++) {
+    compptr = dstinfo->comp_info + ci;
+    comp_width = MCU_cols * compptr->h_samp_factor;
+    comp_height = MCU_rows * compptr->v_samp_factor;
+    x_crop_blocks = x_crop_offset * compptr->h_samp_factor;
+    y_crop_blocks = y_crop_offset * 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 (y_crop_blocks + dst_blk_y < comp_height) {
+	/* Row is within the vertically mirrorable area. */
+	src_buffer = (*srcinfo->mem->access_virt_barray)
+	  ((j_common_ptr) srcinfo, src_coef_arrays[ci],
+	   comp_height - y_crop_blocks - dst_blk_y -
+	   (JDIMENSION) compptr->v_samp_factor,
+	   (JDIMENSION) compptr->v_samp_factor, FALSE);
+      } else {
+	/* Bottom-edge rows are only mirrored horizontally. */
+	src_buffer = (*srcinfo->mem->access_virt_barray)
+	  ((j_common_ptr) srcinfo, src_coef_arrays[ci],
+	   dst_blk_y + y_crop_blocks,
+	   (JDIMENSION) compptr->v_samp_factor, FALSE);
+      }
+      for (offset_y = 0; offset_y < compptr->v_samp_factor; offset_y++) {
+	dst_row_ptr = dst_buffer[offset_y];
+	if (y_crop_blocks + dst_blk_y < comp_height) {
+	  /* Row is within the mirrorable area. */
+	  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];
+	    if (x_crop_blocks + dst_blk_x < comp_width) {
+	      /* Process the blocks that can be mirrored both ways. */
+	      src_ptr = src_row_ptr[comp_width - x_crop_blocks - dst_blk_x - 1];
+	      for (i = 0; i < DCTSIZE; i += 2) {
+		/* For even row, negate every odd column. */
+		for (j = 0; j < DCTSIZE; j += 2) {
+		  *dst_ptr++ = *src_ptr++;
+		  *dst_ptr++ = - *src_ptr++;
+		}
+		/* For odd row, negate every even column. */
+		for (j = 0; j < DCTSIZE; j += 2) {
+		  *dst_ptr++ = - *src_ptr++;
+		  *dst_ptr++ = *src_ptr++;
+		}
+	      }
+	    } else {
+	      /* Any remaining right-edge blocks are only mirrored vertically. */
+	      src_ptr = src_row_ptr[x_crop_blocks + dst_blk_x];
+	      for (i = 0; i < DCTSIZE; i += 2) {
+		for (j = 0; j < DCTSIZE; j++)
+		  *dst_ptr++ = *src_ptr++;
+		for (j = 0; j < DCTSIZE; j++)
+		  *dst_ptr++ = - *src_ptr++;
+	      }
+	    }
+	  }
+	} else {
+	  /* Remaining rows are just mirrored horizontally. */
+	  src_row_ptr = src_buffer[offset_y];
+	  for (dst_blk_x = 0; dst_blk_x < compptr->width_in_blocks; dst_blk_x++) {
+	    if (x_crop_blocks + dst_blk_x < comp_width) {
+	      /* Process the blocks that can be mirrored. */
+	      dst_ptr = dst_row_ptr[dst_blk_x];
+	      src_ptr = src_row_ptr[comp_width - x_crop_blocks - dst_blk_x - 1];
+	      for (i = 0; i < DCTSIZE2; i += 2) {
+		*dst_ptr++ = *src_ptr++;
+		*dst_ptr++ = - *src_ptr++;
+	      }
+	    } else {
+	      /* Any remaining right-edge blocks are only copied. */
+	      jcopy_block_row(src_row_ptr + dst_blk_x + x_crop_blocks,
+			      dst_row_ptr + dst_blk_x,
+			      (JDIMENSION) 1);
+	    }
+	  }
+	}
+      }
+    }
+  }
+}
+
+
+LOCAL(void)
+do_transverse (j_decompress_ptr srcinfo, j_compress_ptr dstinfo,
+	       JDIMENSION x_crop_offset, JDIMENSION y_crop_offset,
+	       jvirt_barray_ptr *src_coef_arrays,
+	       jvirt_barray_ptr *dst_coef_arrays)
+/* Transverse transpose is equivalent to
+ *   1. 180 degree rotation;
+ *   2. Transposition;
+ * or
+ *   1. Horizontal mirroring;
+ *   2. Transposition;
+ *   3. Horizontal mirroring.
+ * These steps are merged into a single processing routine.
+ */
+{
+  JDIMENSION MCU_cols, MCU_rows, comp_width, comp_height, dst_blk_x, dst_blk_y;
+  JDIMENSION x_crop_blocks, y_crop_blocks;
+  int ci, i, j, offset_x, offset_y;
+  JBLOCKARRAY src_buffer, dst_buffer;
+  JCOEFPTR src_ptr, dst_ptr;
+  jpeg_component_info *compptr;
+
+  MCU_cols = srcinfo->output_height /
+    (dstinfo->max_h_samp_factor * dstinfo->min_DCT_h_scaled_size);
+  MCU_rows = srcinfo->output_width /
+    (dstinfo->max_v_samp_factor * dstinfo->min_DCT_v_scaled_size);
+
+  for (ci = 0; ci < dstinfo->num_components; ci++) {
+    compptr = dstinfo->comp_info + ci;
+    comp_width = MCU_cols * compptr->h_samp_factor;
+    comp_height = MCU_rows * compptr->v_samp_factor;
+    x_crop_blocks = x_crop_offset * compptr->h_samp_factor;
+    y_crop_blocks = y_crop_offset * 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);
+      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) {
+	  if (x_crop_blocks + dst_blk_x < comp_width) {
+	    /* Block is within the mirrorable area. */
+	    src_buffer = (*srcinfo->mem->access_virt_barray)
+	      ((j_common_ptr) srcinfo, src_coef_arrays[ci],
+	       comp_width - x_crop_blocks - dst_blk_x -
+	       (JDIMENSION) compptr->h_samp_factor,
+	       (JDIMENSION) compptr->h_samp_factor, FALSE);
+	  } else {
+	    src_buffer = (*srcinfo->mem->access_virt_barray)
+	      ((j_common_ptr) srcinfo, src_coef_arrays[ci],
+	       dst_blk_x + x_crop_blocks,
+	       (JDIMENSION) compptr->h_samp_factor, FALSE);
+	  }
+	  for (offset_x = 0; offset_x < compptr->h_samp_factor; offset_x++) {
+	    dst_ptr = dst_buffer[offset_y][dst_blk_x + offset_x];
+	    if (y_crop_blocks + dst_blk_y < comp_height) {
+	      if (x_crop_blocks + dst_blk_x < comp_width) {
+		/* Block is within the mirrorable area. */
+		src_ptr = src_buffer[compptr->h_samp_factor - offset_x - 1]
+		  [comp_height - y_crop_blocks - dst_blk_y - offset_y - 1];
+		for (i = 0; i < DCTSIZE; i++) {
+		  for (j = 0; j < DCTSIZE; j++) {
+		    dst_ptr[j*DCTSIZE+i] = src_ptr[i*DCTSIZE+j];
+		    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];
+		    j++;
+		    dst_ptr[j*DCTSIZE+i] = src_ptr[i*DCTSIZE+j];
+		  }
+		}
+	      } else {
+		/* Right-edge blocks are mirrored in y only */
+		src_ptr = src_buffer[offset_x]
+		  [comp_height - y_crop_blocks - dst_blk_y - offset_y - 1];
+		for (i = 0; i < DCTSIZE; i++) {
+		  for (j = 0; j < DCTSIZE; j++) {
+		    dst_ptr[j*DCTSIZE+i] = src_ptr[i*DCTSIZE+j];
+		    j++;
+		    dst_ptr[j*DCTSIZE+i] = -src_ptr[i*DCTSIZE+j];
+		  }
+		}
+	      }
+	    } else {
+	      if (x_crop_blocks + dst_blk_x < comp_width) {
+		/* Bottom-edge blocks are mirrored in x only */
+		src_ptr = src_buffer[compptr->h_samp_factor - offset_x - 1]
+		  [dst_blk_y + offset_y + y_crop_blocks];
+		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 {
+		/* At lower right corner, just transpose, no mirroring */
+		src_ptr = src_buffer[offset_x]
+		  [dst_blk_y + offset_y + y_crop_blocks];
+		for (i = 0; i < DCTSIZE; i++)
+		  for (j = 0; j < DCTSIZE; j++)
+		    dst_ptr[j*DCTSIZE+i] = src_ptr[i*DCTSIZE+j];
+	      }
+	    }
+	  }
+	}
+      }
+    }
+  }
+}
+
+
+/* Parse an unsigned integer: subroutine for jtransform_parse_crop_spec.
+ * Returns TRUE if valid integer found, FALSE if not.
+ * *strptr is advanced over the digit string, and *result is set to its value.
+ */
+
+LOCAL(boolean)
+jt_read_integer (const char ** strptr, JDIMENSION * result)
+{
+  const char * ptr = *strptr;
+  JDIMENSION val = 0;
+
+  for (; isdigit(*ptr); ptr++) {
+    val = val * 10 + (JDIMENSION) (*ptr - '0');
+  }
+  *result = val;
+  if (ptr == *strptr)
+    return FALSE;		/* oops, no digits */
+  *strptr = ptr;
+  return TRUE;
+}
+
+
+/* Parse a crop specification (written in X11 geometry style).
+ * The routine returns TRUE if the spec string is valid, FALSE if not.
+ *
+ * The crop spec string should have the format
+ *	<width>[f]x<height>[f]{+-}<xoffset>{+-}<yoffset>
+ * where width, height, xoffset, and yoffset are unsigned integers.
+ * Each of the elements can be omitted to indicate a default value.
+ * (A weakness of this style is that it is not possible to omit xoffset
+ * while specifying yoffset, since they look alike.)
+ *
+ * This code is loosely based on XParseGeometry from the X11 distribution.
+ */
+
+GLOBAL(boolean)
+jtransform_parse_crop_spec (jpeg_transform_info *info, const char *spec)
+{
+  info->crop = FALSE;
+  info->crop_width_set = JCROP_UNSET;
+  info->crop_height_set = JCROP_UNSET;
+  info->crop_xoffset_set = JCROP_UNSET;
+  info->crop_yoffset_set = JCROP_UNSET;
+
+  if (isdigit(*spec)) {
+    /* fetch width */
+    if (! jt_read_integer(&spec, &info->crop_width))
+      return FALSE;
+    if (*spec == 'f' || *spec == 'F') {
+      spec++;
+      info->crop_width_set = JCROP_FORCE;
+    } else
+      info->crop_width_set = JCROP_POS;
+  }
+  if (*spec == 'x' || *spec == 'X') {
+    /* fetch height */
+    spec++;
+    if (! jt_read_integer(&spec, &info->crop_height))
+      return FALSE;
+    if (*spec == 'f' || *spec == 'F') {
+      spec++;
+      info->crop_height_set = JCROP_FORCE;
+    } else
+      info->crop_height_set = JCROP_POS;
+  }
+  if (*spec == '+' || *spec == '-') {
+    /* fetch xoffset */
+    info->crop_xoffset_set = (*spec == '-') ? JCROP_NEG : JCROP_POS;
+    spec++;
+    if (! jt_read_integer(&spec, &info->crop_xoffset))
+      return FALSE;
+  }
+  if (*spec == '+' || *spec == '-') {
+    /* fetch yoffset */
+    info->crop_yoffset_set = (*spec == '-') ? JCROP_NEG : JCROP_POS;
+    spec++;
+    if (! jt_read_integer(&spec, &info->crop_yoffset))
+      return FALSE;
+  }
+  /* We had better have gotten to the end of the string. */
+  if (*spec != '\0')
+    return FALSE;
+  info->crop = TRUE;
+  return TRUE;
+}
+
+
+/* Trim off any partial iMCUs on the indicated destination edge */
+
+LOCAL(void)
+trim_right_edge (jpeg_transform_info *info, JDIMENSION full_width)
+{
+  JDIMENSION MCU_cols;
+
+  MCU_cols = info->output_width / info->iMCU_sample_width;
+  if (MCU_cols > 0 && info->x_crop_offset + MCU_cols ==
+      full_width / info->iMCU_sample_width)
+    info->output_width = MCU_cols * info->iMCU_sample_width;
+}
+
+LOCAL(void)
+trim_bottom_edge (jpeg_transform_info *info, JDIMENSION full_height)
+{
+  JDIMENSION MCU_rows;
+
+  MCU_rows = info->output_height / info->iMCU_sample_height;
+  if (MCU_rows > 0 && info->y_crop_offset + MCU_rows ==
+      full_height / info->iMCU_sample_height)
+    info->output_height = MCU_rows * info->iMCU_sample_height;
+}
+
+
+/* Request any required workspace.
+ *
+ * This routine figures out the size that the output image will be
+ * (which implies that all the transform parameters must be set before
+ * it is called).
+ *
+ * We allocate the workspace virtual arrays from the source decompression
+ * object, so that all the arrays (both the original data and the workspace)
+ * will be taken into account while making memory management decisions.
+ * Hence, this routine must be called after jpeg_read_header (which reads
+ * the image dimensions) and before jpeg_read_coefficients (which realizes
+ * the source's virtual arrays).
+ *
+ * This function returns FALSE right away if -perfect is given
+ * and transformation is not perfect.  Otherwise returns TRUE.
+ */
+
+GLOBAL(boolean)
+jtransform_request_workspace (j_decompress_ptr srcinfo,
+			      jpeg_transform_info *info)
+{
+  jvirt_barray_ptr *coef_arrays;
+  boolean need_workspace, transpose_it;
+  jpeg_component_info *compptr;
+  JDIMENSION xoffset, yoffset;
+  JDIMENSION width_in_iMCUs, height_in_iMCUs;
+  JDIMENSION width_in_blocks, height_in_blocks;
+  int ci, h_samp_factor, v_samp_factor;
+
+  /* Determine number of components in output image */
+  if (info->force_grayscale &&
+      srcinfo->jpeg_color_space == JCS_YCbCr &&
+      srcinfo->num_components == 3)
+    /* We'll only process the first component */
+    info->num_components = 1;
+  else
+    /* Process all the components */
+    info->num_components = srcinfo->num_components;
+
+  /* Compute output image dimensions and related values. */
+  jpeg_core_output_dimensions(srcinfo);
+
+  /* Return right away if -perfect is given and transformation is not perfect.
+   */
+  if (info->perfect) {
+    if (info->num_components == 1) {
+      if (!jtransform_perfect_transform(srcinfo->output_width,
+	  srcinfo->output_height,
+	  srcinfo->min_DCT_h_scaled_size,
+	  srcinfo->min_DCT_v_scaled_size,
+	  info->transform))
+	return FALSE;
+    } else {
+      if (!jtransform_perfect_transform(srcinfo->output_width,
+	  srcinfo->output_height,
+	  srcinfo->max_h_samp_factor * srcinfo->min_DCT_h_scaled_size,
+	  srcinfo->max_v_samp_factor * srcinfo->min_DCT_v_scaled_size,
+	  info->transform))
+	return FALSE;
+    }
+  }
+
+  /* If there is only one output component, force the iMCU size to be 1;
+   * else use the source iMCU size.  (This allows us to do the right thing
+   * when reducing color to grayscale, and also provides a handy way of
+   * cleaning up "funny" grayscale images whose sampling factors are not 1x1.)
+   */
+  switch (info->transform) {
+  case JXFORM_TRANSPOSE:
+  case JXFORM_TRANSVERSE:
+  case JXFORM_ROT_90:
+  case JXFORM_ROT_270:
+    info->output_width = srcinfo->output_height;
+    info->output_height = srcinfo->output_width;
+    if (info->num_components == 1) {
+      info->iMCU_sample_width = srcinfo->min_DCT_v_scaled_size;
+      info->iMCU_sample_height = srcinfo->min_DCT_h_scaled_size;
+    } else {
+      info->iMCU_sample_width =
+	srcinfo->max_v_samp_factor * srcinfo->min_DCT_v_scaled_size;
+      info->iMCU_sample_height =
+	srcinfo->max_h_samp_factor * srcinfo->min_DCT_h_scaled_size;
+    }
+    break;
+  default:
+    info->output_width = srcinfo->output_width;
+    info->output_height = srcinfo->output_height;
+    if (info->num_components == 1) {
+      info->iMCU_sample_width = srcinfo->min_DCT_h_scaled_size;
+      info->iMCU_sample_height = srcinfo->min_DCT_v_scaled_size;
+    } else {
+      info->iMCU_sample_width =
+	srcinfo->max_h_samp_factor * srcinfo->min_DCT_h_scaled_size;
+      info->iMCU_sample_height =
+	srcinfo->max_v_samp_factor * srcinfo->min_DCT_v_scaled_size;
+    }
+    break;
+  }
+
+  /* If cropping has been requested, compute the crop area's position and
+   * dimensions, ensuring that its upper left corner falls at an iMCU boundary.
+   */
+  if (info->crop) {
+    /* Insert default values for unset crop parameters */
+    if (info->crop_xoffset_set == JCROP_UNSET)
+      info->crop_xoffset = 0;	/* default to +0 */
+    if (info->crop_yoffset_set == JCROP_UNSET)
+      info->crop_yoffset = 0;	/* default to +0 */
+    if (info->crop_xoffset >= info->output_width ||
+	info->crop_yoffset >= info->output_height)
+      ERREXIT(srcinfo, JERR_BAD_CROP_SPEC);
+    if (info->crop_width_set == JCROP_UNSET)
+      info->crop_width = info->output_width - info->crop_xoffset;
+    if (info->crop_height_set == JCROP_UNSET)
+      info->crop_height = info->output_height - info->crop_yoffset;
+    /* Ensure parameters are valid */
+    if (info->crop_width <= 0 || info->crop_width > info->output_width ||
+	info->crop_height <= 0 || info->crop_height > info->output_height ||
+	info->crop_xoffset > info->output_width - info->crop_width ||
+	info->crop_yoffset > info->output_height - info->crop_height)
+      ERREXIT(srcinfo, JERR_BAD_CROP_SPEC);
+    /* Convert negative crop offsets into regular offsets */
+    if (info->crop_xoffset_set == JCROP_NEG)
+      xoffset = info->output_width - info->crop_width - info->crop_xoffset;
+    else
+      xoffset = info->crop_xoffset;
+    if (info->crop_yoffset_set == JCROP_NEG)
+      yoffset = info->output_height - info->crop_height - info->crop_yoffset;
+    else
+      yoffset = info->crop_yoffset;
+    /* Now adjust so that upper left corner falls at an iMCU boundary */
+    if (info->crop_width_set == JCROP_FORCE)
+      info->output_width = info->crop_width;
+    else
+      info->output_width =
+        info->crop_width + (xoffset % info->iMCU_sample_width);
+    if (info->crop_height_set == JCROP_FORCE)
+      info->output_height = info->crop_height;
+    else
+      info->output_height =
+        info->crop_height + (yoffset % info->iMCU_sample_height);
+    /* Save x/y offsets measured in iMCUs */
+    info->x_crop_offset = xoffset / info->iMCU_sample_width;
+    info->y_crop_offset = yoffset / info->iMCU_sample_height;
+  } else {
+    info->x_crop_offset = 0;
+    info->y_crop_offset = 0;
+  }
+
+  /* Figure out whether we need workspace arrays,
+   * and if so whether they are transposed relative to the source.
+   */
+  need_workspace = FALSE;
+  transpose_it = FALSE;
+  switch (info->transform) {
+  case JXFORM_NONE:
+    if (info->x_crop_offset != 0 || info->y_crop_offset != 0)
+      need_workspace = TRUE;
+    /* No workspace needed if neither cropping nor transforming */
+    break;
+  case JXFORM_FLIP_H:
+    if (info->trim)
+      trim_right_edge(info, srcinfo->output_width);
+    if (info->y_crop_offset != 0)
+      need_workspace = TRUE;
+    /* do_flip_h_no_crop doesn't need a workspace array */
+    break;
+  case JXFORM_FLIP_V:
+    if (info->trim)
+      trim_bottom_edge(info, srcinfo->output_height);
+    /* Need workspace arrays having same dimensions as source image. */
+    need_workspace = TRUE;
+    break;
+  case JXFORM_TRANSPOSE:
+    /* transpose does NOT have to trim anything */
+    /* Need workspace arrays having transposed dimensions. */
+    need_workspace = TRUE;
+    transpose_it = TRUE;
+    break;
+  case JXFORM_TRANSVERSE:
+    if (info->trim) {
+      trim_right_edge(info, srcinfo->output_height);
+      trim_bottom_edge(info, srcinfo->output_width);
+    }
+    /* Need workspace arrays having transposed dimensions. */
+    need_workspace = TRUE;
+    transpose_it = TRUE;
+    break;
+  case JXFORM_ROT_90:
+    if (info->trim)
+      trim_right_edge(info, srcinfo->output_height);
+    /* Need workspace arrays having transposed dimensions. */
+    need_workspace = TRUE;
+    transpose_it = TRUE;
+    break;
+  case JXFORM_ROT_180:
+    if (info->trim) {
+      trim_right_edge(info, srcinfo->output_width);
+      trim_bottom_edge(info, srcinfo->output_height);
+    }
+    /* Need workspace arrays having same dimensions as source image. */
+    need_workspace = TRUE;
+    break;
+  case JXFORM_ROT_270:
+    if (info->trim)
+      trim_bottom_edge(info, srcinfo->output_width);
+    /* Need workspace arrays having transposed dimensions. */
+    need_workspace = TRUE;
+    transpose_it = TRUE;
+    break;
+  }
+
+  /* Allocate workspace if needed.
+   * Note that we allocate arrays padded out to the next iMCU boundary,
+   * so that transform routines need not worry about missing edge blocks.
+   */
+  if (need_workspace) {
+    coef_arrays = (jvirt_barray_ptr *)
+      (*srcinfo->mem->alloc_small) ((j_common_ptr) srcinfo, JPOOL_IMAGE,
+		SIZEOF(jvirt_barray_ptr) * info->num_components);
+    width_in_iMCUs = (JDIMENSION)
+      jdiv_round_up((long) info->output_width,
+		    (long) info->iMCU_sample_width);
+    height_in_iMCUs = (JDIMENSION)
+      jdiv_round_up((long) info->output_height,
+		    (long) info->iMCU_sample_height);
+    for (ci = 0; ci < info->num_components; ci++) {
+      compptr = srcinfo->comp_info + ci;
+      if (info->num_components == 1) {
+	/* we're going to force samp factors to 1x1 in this case */
+	h_samp_factor = v_samp_factor = 1;
+      } else if (transpose_it) {
+	h_samp_factor = compptr->v_samp_factor;
+	v_samp_factor = compptr->h_samp_factor;
+      } else {
+	h_samp_factor = compptr->h_samp_factor;
+	v_samp_factor = compptr->v_samp_factor;
+      }
+      width_in_blocks = width_in_iMCUs * h_samp_factor;
+      height_in_blocks = height_in_iMCUs * v_samp_factor;
+      coef_arrays[ci] = (*srcinfo->mem->request_virt_barray)
+	((j_common_ptr) srcinfo, JPOOL_IMAGE, FALSE,
+	 width_in_blocks, height_in_blocks, (JDIMENSION) v_samp_factor);
+    }
+    info->workspace_coef_arrays = coef_arrays;
+  } else
+    info->workspace_coef_arrays = NULL;
+
+  return TRUE;
+}
+
+
+/* Transpose destination image parameters */
+
+LOCAL(void)
+transpose_critical_parameters (j_compress_ptr dstinfo)
+{
+  int tblno, i, j, ci, itemp;
+  jpeg_component_info *compptr;
+  JQUANT_TBL *qtblptr;
+  JDIMENSION jtemp;
+  UINT16 qtemp;
+
+  /* Transpose image dimensions */
+  jtemp = dstinfo->image_width;
+  dstinfo->image_width = dstinfo->image_height;
+  dstinfo->image_height = jtemp;
+  itemp = dstinfo->min_DCT_h_scaled_size;
+  dstinfo->min_DCT_h_scaled_size = dstinfo->min_DCT_v_scaled_size;
+  dstinfo->min_DCT_v_scaled_size = itemp;
+
+  /* Transpose sampling factors */
+  for (ci = 0; ci < dstinfo->num_components; ci++) {
+    compptr = dstinfo->comp_info + ci;
+    itemp = compptr->h_samp_factor;
+    compptr->h_samp_factor = compptr->v_samp_factor;
+    compptr->v_samp_factor = itemp;
+  }
+
+  /* Transpose quantization tables */
+  for (tblno = 0; tblno < NUM_QUANT_TBLS; tblno++) {
+    qtblptr = dstinfo->quant_tbl_ptrs[tblno];
+    if (qtblptr != NULL) {
+      for (i = 0; i < DCTSIZE; i++) {
+	for (j = 0; j < i; j++) {
+	  qtemp = qtblptr->quantval[i*DCTSIZE+j];
+	  qtblptr->quantval[i*DCTSIZE+j] = qtblptr->quantval[j*DCTSIZE+i];
+	  qtblptr->quantval[j*DCTSIZE+i] = qtemp;
+	}
+      }
+    }
+  }
+}
+
+
+/* Adjust Exif image parameters.
+ *
+ * We try to adjust the Tags ExifImageWidth and ExifImageHeight if possible.
+ */
+
+LOCAL(void)
+adjust_exif_parameters (JOCTET FAR * data, unsigned int length,
+			JDIMENSION new_width, JDIMENSION new_height)
+{
+  boolean is_motorola; /* Flag for byte order */
+  unsigned int number_of_tags, tagnum;
+  unsigned int firstoffset, offset;
+  JDIMENSION new_value;
+
+  if (length < 12) return; /* Length of an IFD entry */
+
+  /* Discover byte order */
+  if (GETJOCTET(data[0]) == 0x49 && GETJOCTET(data[1]) == 0x49)
+    is_motorola = FALSE;
+  else if (GETJOCTET(data[0]) == 0x4D && GETJOCTET(data[1]) == 0x4D)
+    is_motorola = TRUE;
+  else
+    return;
+
+  /* Check Tag Mark */
+  if (is_motorola) {
+    if (GETJOCTET(data[2]) != 0) return;
+    if (GETJOCTET(data[3]) != 0x2A) return;
+  } else {
+    if (GETJOCTET(data[3]) != 0) return;
+    if (GETJOCTET(data[2]) != 0x2A) return;
+  }
+
+  /* Get first IFD offset (offset to IFD0) */
+  if (is_motorola) {
+    if (GETJOCTET(data[4]) != 0) return;
+    if (GETJOCTET(data[5]) != 0) return;
+    firstoffset = GETJOCTET(data[6]);
+    firstoffset <<= 8;
+    firstoffset += GETJOCTET(data[7]);
+  } else {
+    if (GETJOCTET(data[7]) != 0) return;
+    if (GETJOCTET(data[6]) != 0) return;
+    firstoffset = GETJOCTET(data[5]);
+    firstoffset <<= 8;
+    firstoffset += GETJOCTET(data[4]);
+  }
+  if (firstoffset > length - 2) return; /* check end of data segment */
+
+  /* Get the number of directory entries contained in this IFD */
+  if (is_motorola) {
+    number_of_tags = GETJOCTET(data[firstoffset]);
+    number_of_tags <<= 8;
+    number_of_tags += GETJOCTET(data[firstoffset+1]);
+  } else {
+    number_of_tags = GETJOCTET(data[firstoffset+1]);
+    number_of_tags <<= 8;
+    number_of_tags += GETJOCTET(data[firstoffset]);
+  }
+  if (number_of_tags == 0) return;
+  firstoffset += 2;
+
+  /* Search for ExifSubIFD offset Tag in IFD0 */
+  for (;;) {
+    if (firstoffset > length - 12) return; /* check end of data segment */
+    /* Get Tag number */
+    if (is_motorola) {
+      tagnum = GETJOCTET(data[firstoffset]);
+      tagnum <<= 8;
+      tagnum += GETJOCTET(data[firstoffset+1]);
+    } else {
+      tagnum = GETJOCTET(data[firstoffset+1]);
+      tagnum <<= 8;
+      tagnum += GETJOCTET(data[firstoffset]);
+    }
+    if (tagnum == 0x8769) break; /* found ExifSubIFD offset Tag */
+    if (--number_of_tags == 0) return;
+    firstoffset += 12;
+  }
+
+  /* Get the ExifSubIFD offset */
+  if (is_motorola) {
+    if (GETJOCTET(data[firstoffset+8]) != 0) return;
+    if (GETJOCTET(data[firstoffset+9]) != 0) return;
+    offset = GETJOCTET(data[firstoffset+10]);
+    offset <<= 8;
+    offset += GETJOCTET(data[firstoffset+11]);
+  } else {
+    if (GETJOCTET(data[firstoffset+11]) != 0) return;
+    if (GETJOCTET(data[firstoffset+10]) != 0) return;
+    offset = GETJOCTET(data[firstoffset+9]);
+    offset <<= 8;
+    offset += GETJOCTET(data[firstoffset+8]);
+  }
+  if (offset > length - 2) return; /* check end of data segment */
+
+  /* Get the number of directory entries contained in this SubIFD */
+  if (is_motorola) {
+    number_of_tags = GETJOCTET(data[offset]);
+    number_of_tags <<= 8;
+    number_of_tags += GETJOCTET(data[offset+1]);
+  } else {
+    number_of_tags = GETJOCTET(data[offset+1]);
+    number_of_tags <<= 8;
+    number_of_tags += GETJOCTET(data[offset]);
+  }
+  if (number_of_tags < 2) return;
+  offset += 2;
+
+  /* Search for ExifImageWidth and ExifImageHeight Tags in this SubIFD */
+  do {
+    if (offset > length - 12) return; /* check end of data segment */
+    /* Get Tag number */
+    if (is_motorola) {
+      tagnum = GETJOCTET(data[offset]);
+      tagnum <<= 8;
+      tagnum += GETJOCTET(data[offset+1]);
+    } else {
+      tagnum = GETJOCTET(data[offset+1]);
+      tagnum <<= 8;
+      tagnum += GETJOCTET(data[offset]);
+    }
+    if (tagnum == 0xA002 || tagnum == 0xA003) {
+      if (tagnum == 0xA002)
+	new_value = new_width; /* ExifImageWidth Tag */
+      else
+	new_value = new_height; /* ExifImageHeight Tag */
+      if (is_motorola) {
+	data[offset+2] = 0; /* Format = unsigned long (4 octets) */
+	data[offset+3] = 4;
+	data[offset+4] = 0; /* Number Of Components = 1 */
+	data[offset+5] = 0;
+	data[offset+6] = 0;
+	data[offset+7] = 1;
+	data[offset+8] = 0;
+	data[offset+9] = 0;
+	data[offset+10] = (JOCTET)((new_value >> 8) & 0xFF);
+	data[offset+11] = (JOCTET)(new_value & 0xFF);
+      } else {
+	data[offset+2] = 4; /* Format = unsigned long (4 octets) */
+	data[offset+3] = 0;
+	data[offset+4] = 1; /* Number Of Components = 1 */
+	data[offset+5] = 0;
+	data[offset+6] = 0;
+	data[offset+7] = 0;
+	data[offset+8] = (JOCTET)(new_value & 0xFF);
+	data[offset+9] = (JOCTET)((new_value >> 8) & 0xFF);
+	data[offset+10] = 0;
+	data[offset+11] = 0;
+      }
+    }
+    offset += 12;
+  } while (--number_of_tags);
+}
+
+
+/* Adjust output image parameters as needed.
+ *
+ * This must be called after jpeg_copy_critical_parameters()
+ * and before jpeg_write_coefficients().
+ *
+ * The return value is the set of virtual coefficient arrays to be written
+ * (either the ones allocated by jtransform_request_workspace, or the
+ * original source data arrays).  The caller will need to pass this value
+ * to jpeg_write_coefficients().
+ */
+
+GLOBAL(jvirt_barray_ptr *)
+jtransform_adjust_parameters (j_decompress_ptr srcinfo,
+			      j_compress_ptr dstinfo,
+			      jvirt_barray_ptr *src_coef_arrays,
+			      jpeg_transform_info *info)
+{
+  /* If force-to-grayscale is requested, adjust destination parameters */
+  if (info->force_grayscale) {
+    /* First, ensure we have YCbCr or grayscale data, and that the source's
+     * Y channel is full resolution.  (No reasonable person would make Y
+     * be less than full resolution, so actually coping with that case
+     * isn't worth extra code space.  But we check it to avoid crashing.)
+     */
+    if (((dstinfo->jpeg_color_space == JCS_YCbCr &&
+	  dstinfo->num_components == 3) ||
+	 (dstinfo->jpeg_color_space == JCS_GRAYSCALE &&
+	  dstinfo->num_components == 1)) &&
+	srcinfo->comp_info[0].h_samp_factor == srcinfo->max_h_samp_factor &&
+	srcinfo->comp_info[0].v_samp_factor == srcinfo->max_v_samp_factor) {
+      /* We use jpeg_set_colorspace to make sure subsidiary settings get fixed
+       * properly.  Among other things, it sets the target h_samp_factor &
+       * v_samp_factor to 1, which typically won't match the source.
+       * We have to preserve the source's quantization table number, however.
+       */
+      int sv_quant_tbl_no = dstinfo->comp_info[0].quant_tbl_no;
+      jpeg_set_colorspace(dstinfo, JCS_GRAYSCALE);
+      dstinfo->comp_info[0].quant_tbl_no = sv_quant_tbl_no;
+    } else {
+      /* Sorry, can't do it */
+      ERREXIT(dstinfo, JERR_CONVERSION_NOTIMPL);
+    }
+  } else if (info->num_components == 1) {
+    /* For a single-component source, we force the destination sampling factors
+     * to 1x1, with or without force_grayscale.  This is useful because some
+     * decoders choke on grayscale images with other sampling factors.
+     */
+    dstinfo->comp_info[0].h_samp_factor = 1;
+    dstinfo->comp_info[0].v_samp_factor = 1;
+  }
+
+  /* Correct the destination's image dimensions as necessary
+   * for rotate/flip, resize, and crop operations.
+   */
+  dstinfo->jpeg_width = info->output_width;
+  dstinfo->jpeg_height = info->output_height;
+
+  /* Transpose destination image parameters */
+  switch (info->transform) {
+  case JXFORM_TRANSPOSE:
+  case JXFORM_TRANSVERSE:
+  case JXFORM_ROT_90:
+  case JXFORM_ROT_270:
+    transpose_critical_parameters(dstinfo);
+    break;
+  default:
+    break;
+  }
+
+  /* Adjust Exif properties */
+  if (srcinfo->marker_list != NULL &&
+      srcinfo->marker_list->marker == JPEG_APP0+1 &&
+      srcinfo->marker_list->data_length >= 6 &&
+      GETJOCTET(srcinfo->marker_list->data[0]) == 0x45 &&
+      GETJOCTET(srcinfo->marker_list->data[1]) == 0x78 &&
+      GETJOCTET(srcinfo->marker_list->data[2]) == 0x69 &&
+      GETJOCTET(srcinfo->marker_list->data[3]) == 0x66 &&
+      GETJOCTET(srcinfo->marker_list->data[4]) == 0 &&
+      GETJOCTET(srcinfo->marker_list->data[5]) == 0) {
+    /* Suppress output of JFIF marker */
+    dstinfo->write_JFIF_header = FALSE;
+    /* Adjust Exif image parameters */
+    if (dstinfo->jpeg_width != srcinfo->image_width ||
+	dstinfo->jpeg_height != srcinfo->image_height)
+      /* Align data segment to start of TIFF structure for parsing */
+      adjust_exif_parameters(srcinfo->marker_list->data + 6,
+	srcinfo->marker_list->data_length - 6,
+	dstinfo->jpeg_width, dstinfo->jpeg_height);
+  }
+
+  /* Return the appropriate output data set */
+  if (info->workspace_coef_arrays != NULL)
+    return info->workspace_coef_arrays;
+  return src_coef_arrays;
+}
+
+
+/* Execute the actual transformation, if any.
+ *
+ * This must be called *after* jpeg_write_coefficients, because it depends
+ * on jpeg_write_coefficients to have computed subsidiary values such as
+ * the per-component width and height fields in the destination object.
+ *
+ * Note that some transformations will modify the source data arrays!
+ */
+
+GLOBAL(void)
+jtransform_execute_transform (j_decompress_ptr srcinfo,
+			      j_compress_ptr dstinfo,
+			      jvirt_barray_ptr *src_coef_arrays,
+			      jpeg_transform_info *info)
+{
+  jvirt_barray_ptr *dst_coef_arrays = info->workspace_coef_arrays;
+
+  /* Note: conditions tested here should match those in switch statement
+   * in jtransform_request_workspace()
+   */
+  switch (info->transform) {
+  case JXFORM_NONE:
+    if (info->x_crop_offset != 0 || info->y_crop_offset != 0)
+      do_crop(srcinfo, dstinfo, info->x_crop_offset, info->y_crop_offset,
+	      src_coef_arrays, dst_coef_arrays);
+    break;
+  case JXFORM_FLIP_H:
+    if (info->y_crop_offset != 0)
+      do_flip_h(srcinfo, dstinfo, info->x_crop_offset, info->y_crop_offset,
+		src_coef_arrays, dst_coef_arrays);
+    else
+      do_flip_h_no_crop(srcinfo, dstinfo, info->x_crop_offset,
+			src_coef_arrays);
+    break;
+  case JXFORM_FLIP_V:
+    do_flip_v(srcinfo, dstinfo, info->x_crop_offset, info->y_crop_offset,
+	      src_coef_arrays, dst_coef_arrays);
+    break;
+  case JXFORM_TRANSPOSE:
+    do_transpose(srcinfo, dstinfo, info->x_crop_offset, info->y_crop_offset,
+		 src_coef_arrays, dst_coef_arrays);
+    break;
+  case JXFORM_TRANSVERSE:
+    do_transverse(srcinfo, dstinfo, info->x_crop_offset, info->y_crop_offset,
+		  src_coef_arrays, dst_coef_arrays);
+    break;
+  case JXFORM_ROT_90:
+    do_rot_90(srcinfo, dstinfo, info->x_crop_offset, info->y_crop_offset,
+	      src_coef_arrays, dst_coef_arrays);
+    break;
+  case JXFORM_ROT_180:
+    do_rot_180(srcinfo, dstinfo, info->x_crop_offset, info->y_crop_offset,
+	       src_coef_arrays, dst_coef_arrays);
+    break;
+  case JXFORM_ROT_270:
+    do_rot_270(srcinfo, dstinfo, info->x_crop_offset, info->y_crop_offset,
+	       src_coef_arrays, dst_coef_arrays);
+    break;
+  }
+}
+
+/* jtransform_perfect_transform
+ *
+ * Determine whether lossless transformation is perfectly
+ * possible for a specified image and transformation.
+ *
+ * Inputs:
+ *   image_width, image_height: source image dimensions.
+ *   MCU_width, MCU_height: pixel dimensions of MCU.
+ *   transform: transformation identifier.
+ * Parameter sources from initialized jpeg_struct
+ * (after reading source header):
+ *   image_width = cinfo.image_width
+ *   image_height = cinfo.image_height
+ *   MCU_width = cinfo.max_h_samp_factor * cinfo.block_size
+ *   MCU_height = cinfo.max_v_samp_factor * cinfo.block_size
+ * Result:
+ *   TRUE = perfect transformation possible
+ *   FALSE = perfect transformation not possible
+ *           (may use custom action then)
+ */
+
+GLOBAL(boolean)
+jtransform_perfect_transform(JDIMENSION image_width, JDIMENSION image_height,
+			     int MCU_width, int MCU_height,
+			     JXFORM_CODE transform)
+{
+  boolean result = TRUE; /* initialize TRUE */
+
+  switch (transform) {
+  case JXFORM_FLIP_H:
+  case JXFORM_ROT_270:
+    if (image_width % (JDIMENSION) MCU_width)
+      result = FALSE;
+    break;
+  case JXFORM_FLIP_V:
+  case JXFORM_ROT_90:
+    if (image_height % (JDIMENSION) MCU_height)
+      result = FALSE;
+    break;
+  case JXFORM_TRANSVERSE:
+  case JXFORM_ROT_180:
+    if (image_width % (JDIMENSION) MCU_width)
+      result = FALSE;
+    if (image_height % (JDIMENSION) MCU_height)
+      result = FALSE;
+    break;
+  default:
+    break;
+  }
+
+  return result;
+}
+
+#endif /* TRANSFORMS_SUPPORTED */
+
+
+/* Setup decompression object to save desired markers in memory.
+ * This must be called before jpeg_read_header() to have the desired effect.
+ */
+
+GLOBAL(void)
+jcopy_markers_setup (j_decompress_ptr srcinfo, JCOPY_OPTION option)
+{
+#ifdef SAVE_MARKERS_SUPPORTED
+  int m;
+
+  /* Save comments except under NONE option */
+  if (option != JCOPYOPT_NONE) {
+    jpeg_save_markers(srcinfo, JPEG_COM, 0xFFFF);
+  }
+  /* Save all types of APPn markers iff ALL option */
+  if (option == JCOPYOPT_ALL) {
+    for (m = 0; m < 16; m++)
+      jpeg_save_markers(srcinfo, JPEG_APP0 + m, 0xFFFF);
+  }
+#endif /* SAVE_MARKERS_SUPPORTED */
+}
+
+/* Copy markers saved in the given source object to the destination object.
+ * This should be called just after jpeg_start_compress() or
+ * jpeg_write_coefficients().
+ * Note that those routines will have written the SOI, and also the
+ * JFIF APP0 or Adobe APP14 markers if selected.
+ */
+
+GLOBAL(void)
+jcopy_markers_execute (j_decompress_ptr srcinfo, j_compress_ptr dstinfo,
+		       JCOPY_OPTION option)
+{
+  jpeg_saved_marker_ptr marker;
+
+  /* In the current implementation, we don't actually need to examine the
+   * option flag here; we just copy everything that got saved.
+   * But to avoid confusion, we do not output JFIF and Adobe APP14 markers
+   * if the encoder library already wrote one.
+   */
+  for (marker = srcinfo->marker_list; marker != NULL; marker = marker->next) {
+    if (dstinfo->write_JFIF_header &&
+	marker->marker == JPEG_APP0 &&
+	marker->data_length >= 5 &&
+	GETJOCTET(marker->data[0]) == 0x4A &&
+	GETJOCTET(marker->data[1]) == 0x46 &&
+	GETJOCTET(marker->data[2]) == 0x49 &&
+	GETJOCTET(marker->data[3]) == 0x46 &&
+	GETJOCTET(marker->data[4]) == 0)
+      continue;			/* reject duplicate JFIF */
+    if (dstinfo->write_Adobe_marker &&
+	marker->marker == JPEG_APP0+14 &&
+	marker->data_length >= 5 &&
+	GETJOCTET(marker->data[0]) == 0x41 &&
+	GETJOCTET(marker->data[1]) == 0x64 &&
+	GETJOCTET(marker->data[2]) == 0x6F &&
+	GETJOCTET(marker->data[3]) == 0x62 &&
+	GETJOCTET(marker->data[4]) == 0x65)
+      continue;			/* reject duplicate Adobe */
+#ifdef NEED_FAR_POINTERS
+    /* We could use jpeg_write_marker if the data weren't FAR... */
+    {
+      unsigned int i;
+      jpeg_write_m_header(dstinfo, marker->marker, marker->data_length);
+      for (i = 0; i < marker->data_length; i++)
+	jpeg_write_m_byte(dstinfo, marker->data[i]);
+    }
+#else
+    jpeg_write_marker(dstinfo, marker->marker,
+		      marker->data, marker->data_length);
+#endif
+  }
+}