Imported from libpng-0.71.tar
diff --git a/pngwutil.c b/pngwutil.c
new file mode 100644
index 0000000..89743d7
--- /dev/null
+++ b/pngwutil.c
@@ -0,0 +1,1080 @@
+
+/* pngwutil.c - utilities to write a png file
+
+ libpng 1.0 beta 1 - version 0.71
+ For conditions of distribution and use, see copyright notice in png.h
+ Copyright (c) 1995 Guy Eric Schalnat, Group 42, Inc.
+ June 26, 1995
+ */
+#define PNG_INTERNAL
+#include "png.h"
+
+/* place a 32 bit number into a buffer in png byte order. We work
+ with unsigned numbers for convenience, you may have to cast
+ signed numbers (if you use any, most png data is unsigned). */
+void
+png_save_uint_32(png_byte *buf, png_uint_32 i)
+{
+ buf[0] = (png_byte)((i >> 24) & 0xff);
+ buf[1] = (png_byte)((i >> 16) & 0xff);
+ buf[2] = (png_byte)((i >> 8) & 0xff);
+ buf[3] = (png_byte)(i & 0xff);
+}
+
+/* place a 16 bit number into a buffer in png byte order */
+void
+png_save_uint_16(png_byte *buf, png_uint_16 i)
+{
+ buf[0] = (png_byte)((i >> 8) & 0xff);
+ buf[1] = (png_byte)(i & 0xff);
+}
+
+/* write a 32 bit number */
+void
+png_write_uint_32(png_struct *png_ptr, png_uint_32 i)
+{
+ png_byte buf[4];
+
+ buf[0] = (png_byte)((i >> 24) & 0xff);
+ buf[1] = (png_byte)((i >> 16) & 0xff);
+ buf[2] = (png_byte)((i >> 8) & 0xff);
+ buf[3] = (png_byte)(i & 0xff);
+ png_write_data(png_ptr, buf, 4);
+}
+
+/* write a 16 bit number */
+void
+png_write_uint_16(png_struct *png_ptr, png_uint_16 i)
+{
+ png_byte buf[2];
+
+ buf[0] = (png_byte)((i >> 8) & 0xff);
+ buf[1] = (png_byte)(i & 0xff);
+ png_write_data(png_ptr, buf, 2);
+}
+
+/* Write a png chunk all at once. The type is an array of ASCII characters
+ representing the chunk name. The array must be at least 4 bytes in
+ length, and does not need to be null terminated. To be safe, pass the
+ pre-defined chunk names here, and if you need a new one, define it
+ where the others are defined. The length is the length of the data.
+ All the data must be present. If that is not possible, use the
+ png_write_chunk_start(), png_write_chunk_data(), and png_write_chunk_end()
+ functions instead. */
+void
+png_write_chunk(png_struct *png_ptr, png_byte *type,
+ png_byte *data, png_uint_32 length)
+{
+ /* write length */
+ png_write_uint_32(png_ptr, length);
+ /* write chunk name */
+ png_write_data(png_ptr, type, (png_uint_32)4);
+ /* reset the crc and run the chunk name over it */
+ png_reset_crc(png_ptr);
+ png_calculate_crc(png_ptr, type, (png_uint_32)4);
+ /* write the data and update the crc */
+ if (length)
+ {
+ png_calculate_crc(png_ptr, data, length);
+ png_write_data(png_ptr, data, length);
+ }
+ /* write the crc */
+ png_write_uint_32(png_ptr, ~png_ptr->crc);
+}
+
+/* Write the start of a png chunk. The type is the chunk type.
+ The total_length is the sum of the lengths of all the data you will be
+ passing in png_write_chunk_data() */
+void
+png_write_chunk_start(png_struct *png_ptr, png_byte *type,
+ png_uint_32 total_length)
+{
+ /* write the length */
+ png_write_uint_32(png_ptr, total_length);
+ /* write the chunk name */
+ png_write_data(png_ptr, type, (png_uint_32)4);
+ /* reset the crc and run it over the chunk name */
+ png_reset_crc(png_ptr);
+ png_calculate_crc(png_ptr, type, (png_uint_32)4);
+}
+
+/* write the data of a png chunk started with png_write_chunk_start().
+ Note that multiple calls to this function are allowed, and that the
+ sum of the lengths from these calls *must* add up to the total_length
+ given to png_write_chunk_start() */
+void
+png_write_chunk_data(png_struct *png_ptr, png_byte *data, png_uint_32 length)
+{
+ /* write the data, and run the crc over it */
+ if (length)
+ {
+ png_calculate_crc(png_ptr, data, length);
+ png_write_data(png_ptr, data, length);
+ }
+}
+
+/* finish a chunk started with png_write_chunk_start() */
+void
+png_write_chunk_end(png_struct *png_ptr)
+{
+ /* write the crc */
+ png_write_uint_32(png_ptr, ~png_ptr->crc);
+}
+
+/* simple function to write the signature */
+void
+png_write_sig(png_struct *png_ptr)
+{
+ /* write the 8 byte signature */
+ png_write_data(png_ptr, png_sig, (png_uint_32)8);
+}
+
+/* Write the IHDR chunk, and update the png_struct with the necessary
+ information. Note that the rest of this code depends upon this
+ information being correct. */
+void
+png_write_IHDR(png_struct *png_ptr, png_uint_32 width, png_uint_32 height,
+ int bit_depth, int color_type, int compression_type, int filter_type,
+ int interlace_type)
+{
+ png_byte buf[13]; /* buffer to store the IHDR info */
+
+ /* pack the header information into the buffer */
+ png_save_uint_32(buf, width);
+ png_save_uint_32(buf + 4, height);
+ buf[8] = bit_depth;
+ buf[9] = color_type;
+ buf[10] = compression_type;
+ buf[11] = filter_type;
+ buf[12] = interlace_type;
+ /* save off the relevent information */
+ png_ptr->bit_depth = bit_depth;
+ png_ptr->color_type = color_type;
+ png_ptr->interlaced = interlace_type;
+ png_ptr->width = width;
+ png_ptr->height = height;
+
+ switch (color_type)
+ {
+ case 0:
+ case 3:
+ png_ptr->channels = 1;
+ break;
+ case 2:
+ png_ptr->channels = 3;
+ break;
+ case 4:
+ png_ptr->channels = 2;
+ break;
+ case 6:
+ png_ptr->channels = 4;
+ break;
+ }
+ png_ptr->pixel_depth = bit_depth * png_ptr->channels;
+ png_ptr->rowbytes = ((width * (png_uint_32)png_ptr->pixel_depth + 7) >> 3);
+ /* set the usr info, so any transformations can modify it */
+ png_ptr->usr_width = png_ptr->width;
+ png_ptr->usr_bit_depth = png_ptr->bit_depth;
+ png_ptr->usr_channels = png_ptr->channels;
+
+ /* write the chunk */
+ png_write_chunk(png_ptr, png_IHDR, buf, (png_uint_32)13);
+}
+
+/* write the palette. We are careful not to trust png_color to be in the
+ correct order for PNG, so people can redefine it to any convient
+ structure. */
+void
+png_write_PLTE(png_struct *png_ptr, png_color *palette, int number)
+{
+ int i;
+ png_color *pal_ptr;
+ png_byte buf[3];
+
+ png_write_chunk_start(png_ptr, png_PLTE, number * 3);
+ for (i = 0, pal_ptr = palette;
+ i < number;
+ i++, pal_ptr++)
+ {
+ buf[0] = pal_ptr->red;
+ buf[1] = pal_ptr->green;
+ buf[2] = pal_ptr->blue;
+ png_write_chunk_data(png_ptr, buf, (png_uint_32)3);
+ }
+ png_write_chunk_end(png_ptr);
+}
+
+/* write an IDAT chunk */
+void
+png_write_IDAT(png_struct *png_ptr, png_byte *data, png_uint_32 length)
+{
+#ifdef zlibinout
+/* temp zlib problem */
+{
+ extern FILE *fpzlibout;
+
+ fwrite(data, 1, length, fpzlibout);
+}
+/* end temp zlib problem */
+#endif
+
+ png_write_chunk(png_ptr, png_IDAT, data, length);
+}
+
+/* write an IEND chunk */
+void
+png_write_IEND(png_struct *png_ptr)
+{
+ png_write_chunk(png_ptr, png_IEND, NULL, (png_uint_32)0);
+}
+
+/* write a gAMA chunk */
+void
+png_write_gAMA(png_struct *png_ptr, float gamma)
+{
+ png_uint_32 igamma;
+ png_byte buf[4];
+
+ /* gamma is saved in 1/100,000ths */
+ igamma = (png_uint_32)(gamma * 100000.0 + 0.5);
+ png_save_uint_32(buf, igamma);
+ png_write_chunk(png_ptr, png_gAMA, buf, (png_uint_32)4);
+}
+
+/* write the sBIT chunk */
+void
+png_write_sBIT(png_struct *png_ptr, png_color_8 *sbit, int color_type)
+{
+ png_byte buf[4];
+ int size;
+
+ /* make sure we don't depend upon the order of png_color_8 */
+ if (color_type & PNG_COLOR_MASK_COLOR)
+ {
+ buf[0] = sbit->red;
+ buf[1] = sbit->green;
+ buf[2] = sbit->blue;
+ size = 3;
+ }
+ else
+ {
+ buf[0] = sbit->gray;
+ size = 1;
+ }
+
+ if (color_type & PNG_COLOR_MASK_ALPHA)
+ {
+ buf[size++] = sbit->alpha;
+ }
+
+ png_write_chunk(png_ptr, png_sBIT, buf, (png_uint_32)size);
+}
+
+/* write the cHRM chunk */
+void
+png_write_cHRM(png_struct *png_ptr, float white_x, float white_y,
+ float red_x, float red_y, float green_x, float green_y,
+ float blue_x, float blue_y)
+{
+ png_uint_32 itemp;
+ png_byte buf[32];
+
+ /* each value is saved int 1/100,000ths */
+ itemp = (png_uint_32)(white_x * 100000.0 + 0.5);
+ png_save_uint_32(buf, itemp);
+ itemp = (png_uint_32)(white_y * 100000.0 + 0.5);
+ png_save_uint_32(buf + 4, itemp);
+ itemp = (png_uint_32)(red_x * 100000.0 + 0.5);
+ png_save_uint_32(buf + 8, itemp);
+ itemp = (png_uint_32)(red_y * 100000.0 + 0.5);
+ png_save_uint_32(buf + 12, itemp);
+ itemp = (png_uint_32)(green_x * 100000.0 + 0.5);
+ png_save_uint_32(buf + 16, itemp);
+ itemp = (png_uint_32)(green_y * 100000.0 + 0.5);
+ png_save_uint_32(buf + 20, itemp);
+ itemp = (png_uint_32)(blue_x * 100000.0 + 0.5);
+ png_save_uint_32(buf + 24, itemp);
+ itemp = (png_uint_32)(blue_y * 100000.0 + 0.5);
+ png_save_uint_32(buf + 28, itemp);
+ png_write_chunk(png_ptr, png_cHRM, buf, (png_uint_32)32);
+}
+
+/* write the tRNS chunk */
+void
+png_write_tRNS(png_struct *png_ptr, png_byte *trans, png_color_16 *tran,
+ int num_trans, int color_type)
+{
+ png_byte buf[6];
+
+ if (color_type == PNG_COLOR_TYPE_PALETTE)
+ {
+ /* write the chunk out as it is */
+ png_write_chunk(png_ptr, png_tRNS, trans, (png_uint_32)num_trans);
+ }
+ else if (color_type == PNG_COLOR_TYPE_GRAY)
+ {
+ /* one 16 bit value */
+ png_save_uint_16(buf, tran->gray);
+ png_write_chunk(png_ptr, png_tRNS, buf, (png_uint_32)2);
+ }
+ else if (color_type == PNG_COLOR_TYPE_RGB)
+ {
+ /* three 16 bit values */
+ png_save_uint_16(buf, tran->red);
+ png_save_uint_16(buf + 2, tran->green);
+ png_save_uint_16(buf + 4, tran->blue);
+ png_write_chunk(png_ptr, png_tRNS, buf, (png_uint_32)6);
+ }
+}
+
+/* write the background chunk */
+void
+png_write_bKGD(png_struct *png_ptr, png_color_16 *back, int color_type)
+{
+ png_byte buf[6];
+
+ if (color_type == PNG_COLOR_TYPE_PALETTE)
+ {
+ buf[0] = back->index;
+ png_write_chunk(png_ptr, png_bKGD, buf, (png_uint_32)1);
+ }
+ else if (color_type & PNG_COLOR_MASK_COLOR)
+ {
+ png_save_uint_16(buf, back->red);
+ png_save_uint_16(buf + 2, back->green);
+ png_save_uint_16(buf + 4, back->blue);
+ png_write_chunk(png_ptr, png_bKGD, buf, (png_uint_32)6);
+ }
+ else
+ {
+ png_save_uint_16(buf, back->gray);
+ png_write_chunk(png_ptr, png_bKGD, buf, (png_uint_32)2);
+ }
+}
+
+/* write the histogram */
+void
+png_write_hIST(png_struct *png_ptr, png_uint_16 *hist, int number)
+{
+ int i;
+ png_byte buf[3];
+
+ png_write_chunk_start(png_ptr, png_hIST, (png_uint_32)(number * 2));
+ for (i = 0; i < number; i++)
+ {
+ png_save_uint_16(buf, hist[i]);
+ png_write_chunk_data(png_ptr, buf, (png_uint_32)2);
+ }
+ png_write_chunk_end(png_ptr);
+}
+
+/* write a tEXt chunk */
+void
+png_write_tEXt(png_struct *png_ptr, char *key, char *text,
+ png_uint_32 text_len)
+{
+ int key_len;
+
+ key_len = strlen(key);
+ /* make sure we count the 0 after the key */
+ png_write_chunk_start(png_ptr, png_tEXt,
+ (png_uint_32)(key_len + text_len + 1));
+ /* key has an 0 at the end. How nice */
+ png_write_chunk_data(png_ptr, (png_byte *)key, (png_uint_32)(key_len + 1));
+ if (text && text_len)
+ png_write_chunk_data(png_ptr, (png_byte *)text, (png_uint_32)text_len);
+ png_write_chunk_end(png_ptr);
+}
+
+/* write a compressed chunk */
+void
+png_write_zTXt(png_struct *png_ptr, char *key, char *text,
+ png_uint_32 text_len, int compression)
+{
+ int key_len;
+ char buf[1];
+ int i, ret;
+ char **output_ptr = NULL; /* array of pointers to output */
+ int num_output_ptr = 0; /* number of output pointers used */
+ int max_output_ptr = 0; /* size of output_ptr */
+
+ key_len = strlen(key);
+
+ /* we can't write the chunk until we find out how much data we have,
+ which means we need to run the compresser first, and save the
+ output. This shouldn't be a problem, as the vast majority of
+ comments should be reasonable, but we will set up an array of
+ malloced pointers to be sure. */
+
+ /* set up the compression buffers */
+ png_ptr->zstream->avail_in = (uInt)text_len;
+ png_ptr->zstream->next_in = (Byte *)text;
+ png_ptr->zstream->avail_out = (uInt)png_ptr->zbuf_size;
+ png_ptr->zstream->next_out = (Byte *)png_ptr->zbuf;
+
+ /* this is the same compression loop as in png_write_row() */
+ do
+ {
+ /* compress the data */
+ ret = deflate(png_ptr->zstream, Z_NO_FLUSH);
+ if (ret != Z_OK)
+ {
+ /* error */
+ if (png_ptr->zstream->msg)
+ png_error(png_ptr, png_ptr->zstream->msg);
+ else
+ png_error(png_ptr, "zlib error");
+ }
+ /* check to see if we need more room */
+ if (!png_ptr->zstream->avail_out && png_ptr->zstream->avail_in)
+ {
+ /* make sure the output array has room */
+ if (num_output_ptr >= max_output_ptr)
+ {
+ max_output_ptr = num_output_ptr + 4;
+ if (output_ptr)
+ output_ptr = png_realloc(png_ptr, output_ptr,
+ max_output_ptr * sizeof (char *));
+ else
+ output_ptr = png_malloc(png_ptr,
+ max_output_ptr * sizeof (char *));
+ }
+
+ /* save the data */
+ output_ptr[num_output_ptr] = png_large_malloc(png_ptr,
+ png_ptr->zbuf_size);
+ memcpy(output_ptr[num_output_ptr], png_ptr->zbuf,
+ (png_size_t)png_ptr->zbuf_size);
+ num_output_ptr++;
+
+ /* and reset the buffer */
+ png_ptr->zstream->avail_out = (uInt)png_ptr->zbuf_size;
+ png_ptr->zstream->next_out = png_ptr->zbuf;
+ }
+ /* continue until we don't have anymore to compress */
+ } while (png_ptr->zstream->avail_in);
+
+ /* finish the compression */
+ do
+ {
+ /* tell zlib we are finished */
+ ret = deflate(png_ptr->zstream, Z_FINISH);
+ if (ret != Z_OK && ret != Z_STREAM_END)
+ {
+ /* we got an error */
+ if (png_ptr->zstream->msg)
+ png_error(png_ptr, png_ptr->zstream->msg);
+ else
+ png_error(png_ptr, "zlib error");
+ }
+
+ /* check to see if we need more room */
+ if (!png_ptr->zstream->avail_out && ret == Z_OK)
+ {
+ /* check to make sure our output array has room */
+ if (num_output_ptr >= max_output_ptr)
+ {
+ max_output_ptr = num_output_ptr + 4;
+ if (output_ptr)
+ output_ptr = png_realloc(png_ptr, output_ptr,
+ max_output_ptr * sizeof (char *));
+ else
+ output_ptr = png_malloc(png_ptr,
+ max_output_ptr * sizeof (char *));
+ }
+
+ /* save off the data */
+ output_ptr[num_output_ptr] = png_large_malloc(png_ptr,
+ png_ptr->zbuf_size);
+ memcpy(output_ptr[num_output_ptr], png_ptr->zbuf,
+ (png_size_t)png_ptr->zbuf_size);
+ num_output_ptr++;
+
+ /* and reset the buffer pointers */
+ png_ptr->zstream->avail_out = (uInt)png_ptr->zbuf_size;
+ png_ptr->zstream->next_out = png_ptr->zbuf;
+ }
+ } while (ret != Z_STREAM_END);
+
+ /* text length is number of buffers plus last buffer */
+ text_len = png_ptr->zbuf_size * num_output_ptr;
+ if (png_ptr->zstream->avail_out < png_ptr->zbuf_size)
+ text_len += (png_uint_32)(png_ptr->zbuf_size -
+ png_ptr->zstream->avail_out);
+
+ /* write start of chunk */
+ png_write_chunk_start(png_ptr, png_zTXt,
+ (png_uint_32)(key_len + text_len + 2));
+ /* write key */
+ png_write_chunk_data(png_ptr, (png_byte *)key, (png_uint_32)(key_len + 1));
+ buf[0] = compression;
+ /* write compression */
+ png_write_chunk_data(png_ptr, (png_byte *)buf, (png_uint_32)1);
+
+ /* write saved output buffers, if any */
+ for (i = 0; i < num_output_ptr; i++)
+ {
+ png_write_chunk_data(png_ptr, (png_byte *)output_ptr[i], png_ptr->zbuf_size);
+ png_large_free(png_ptr, output_ptr[i]);
+ }
+ if (max_output_ptr)
+ png_free(png_ptr, output_ptr);
+ /* write anything left in zbuf */
+ if (png_ptr->zstream->avail_out < png_ptr->zbuf_size)
+ png_write_chunk_data(png_ptr, png_ptr->zbuf,
+ png_ptr->zbuf_size - png_ptr->zstream->avail_out);
+ /* close the chunk */
+ png_write_chunk_end(png_ptr);
+
+ /* reset zlib for another zTXt or the image data */
+/* deflateReset(png_ptr->zstream); */
+ deflateEnd(png_ptr->zstream);
+ deflateInit(png_ptr->zstream, -1);
+}
+
+/* write the pHYs chunk */
+void
+png_write_pHYs(png_struct *png_ptr, png_uint_32 x_pixels_per_unit,
+ png_uint_32 y_pixels_per_unit,
+ int unit_type)
+{
+ png_byte buf[9];
+
+ png_save_uint_32(buf, x_pixels_per_unit);
+ png_save_uint_32(buf + 4, y_pixels_per_unit);
+ buf[8] = unit_type;
+
+ png_write_chunk(png_ptr, png_pHYs, buf, (png_uint_32)9);
+}
+
+/* write the oFFs chunk */
+void
+png_write_oFFs(png_struct *png_ptr, png_uint_32 x_offset,
+ png_uint_32 y_offset,
+ int unit_type)
+{
+ png_byte buf[9];
+
+ png_save_uint_32(buf, x_offset);
+ png_save_uint_32(buf + 4, y_offset);
+ buf[8] = unit_type;
+
+ png_write_chunk(png_ptr, png_oFFs, buf, (png_uint_32)9);
+}
+
+/* two time chunks are given. This chunk assumes you have a gmtime()
+ function. If you don't have that, use the other tIME function */
+void
+png_write_tIME(png_struct *png_ptr, png_time *mod_time)
+{
+ png_byte buf[7];
+
+ png_save_uint_16(buf, mod_time->year);
+ buf[2] = mod_time->month;
+ buf[3] = mod_time->day;
+ buf[4] = mod_time->hour;
+ buf[5] = mod_time->minute;
+ buf[6] = mod_time->second;
+
+ png_write_chunk(png_ptr, png_tIME, buf, (png_uint_32)7);
+}
+
+/* initializes the row writing capability of libpng */
+void
+png_write_start_row(png_struct *png_ptr)
+{
+ /* set up row buffer */
+ png_ptr->row_buf = (png_byte *)png_large_malloc(png_ptr,
+ (((png_uint_32)png_ptr->usr_channels *
+ (png_uint_32)png_ptr->usr_bit_depth *
+ png_ptr->width) >> 3) + 1);
+ /* set up filtering buffers, if filtering */
+ if (png_ptr->bit_depth >= 8 && png_ptr->color_type != 3)
+ {
+ png_ptr->prev_row = (png_byte *)png_large_malloc(png_ptr,
+ png_ptr->rowbytes + 1);
+ memset(png_ptr->prev_row, 0, (png_size_t)png_ptr->rowbytes + 1);
+ png_ptr->save_row = (png_byte *)png_large_malloc(png_ptr,
+ png_ptr->rowbytes + 1);
+ memset(png_ptr->save_row, 0, (png_size_t)png_ptr->rowbytes + 1);
+ }
+
+ /* if interlaced, we need to set up width and height of pass */
+ if (png_ptr->interlaced)
+ {
+ if (!(png_ptr->transformations & PNG_INTERLACE))
+ {
+ png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 -
+ png_pass_ystart[0]) / png_pass_yinc[0];
+ png_ptr->usr_width = (png_ptr->width +
+ png_pass_inc[0] - 1 -
+ png_pass_start[0]) /
+ png_pass_inc[0];
+ }
+ else
+ {
+ png_ptr->num_rows = png_ptr->height;
+ png_ptr->usr_width = png_ptr->width;
+ }
+ }
+ else
+ {
+ png_ptr->num_rows = png_ptr->height;
+ png_ptr->usr_width = png_ptr->width;
+ }
+ png_ptr->zstream->avail_out = (uInt)png_ptr->zbuf_size;
+ png_ptr->zstream->next_out = png_ptr->zbuf;
+}
+
+/* Internal use only. Called when finished processing a row of data */
+void
+png_write_finish_row(png_struct *png_ptr)
+{
+ int ret;
+
+ /* next row */
+ png_ptr->row_number++;
+ /* see if we are done */
+ if (png_ptr->row_number < png_ptr->num_rows)
+ return;
+
+ /* if interlaced, go to next pass */
+ if (png_ptr->interlaced)
+ {
+ png_ptr->row_number = 0;
+ if (png_ptr->transformations & PNG_INTERLACE)
+ {
+ png_ptr->pass++;
+ }
+ else
+ {
+ /* loop until we find a non-zero width or height pass */
+ do
+ {
+ png_ptr->pass++;
+ if (png_ptr->pass >= 7)
+ break;
+ png_ptr->usr_width = (png_ptr->width +
+ png_pass_inc[png_ptr->pass] - 1 -
+ png_pass_start[png_ptr->pass]) /
+ png_pass_inc[png_ptr->pass];
+ png_ptr->num_rows = (png_ptr->height +
+ png_pass_yinc[png_ptr->pass] - 1 -
+ png_pass_ystart[png_ptr->pass]) /
+ png_pass_yinc[png_ptr->pass];
+ } while (png_ptr->usr_width == 0 || png_ptr->num_rows == 0);
+
+ }
+
+ /* reset filter row */
+ if (png_ptr->prev_row)
+ memset(png_ptr->prev_row, 0, (png_size_t)png_ptr->rowbytes + 1);
+ /* if we have more data to get, go get it */
+ if (png_ptr->pass < 7)
+ return;
+ }
+
+ /* if we get here, we've just written the last row, so we need
+ to flush the compressor */
+ do
+ {
+ /* tell the compressor we are done */
+ ret = deflate(png_ptr->zstream, Z_FINISH);
+ /* check for an error */
+ if (ret != Z_OK && ret != Z_STREAM_END)
+ {
+ if (png_ptr->zstream->msg)
+ png_error(png_ptr, png_ptr->zstream->msg);
+ else
+ png_error(png_ptr, "zlib error");
+ }
+ /* check to see if we need more room */
+ if (!png_ptr->zstream->avail_out && ret == Z_OK)
+ {
+ png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size);
+ png_ptr->zstream->next_out = png_ptr->zbuf;
+ png_ptr->zstream->avail_out = (uInt)png_ptr->zbuf_size;
+ }
+ } while (ret != Z_STREAM_END);
+
+ /* write any extra space */
+ if (png_ptr->zstream->avail_out < png_ptr->zbuf_size)
+ {
+ png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size -
+ png_ptr->zstream->avail_out);
+ }
+
+/* deflateReset(png_ptr->zstream); */
+ deflateEnd(png_ptr->zstream);
+ deflateInit(png_ptr->zstream, -1);
+
+}
+
+/* pick out the correct pixels for the interlace pass.
+
+ The basic idea here is to go through the row with a source
+ pointer and a destination pointer (sp and dp), and copy the
+ correct pixels for the pass. As the row gets compacted,
+ sp will always be >= dp, so we should never overwrite anything.
+ See the default: case for the easiest code to understand.
+ */
+void
+png_do_write_interlace(png_row_info *row_info, png_byte *row, int pass)
+{
+ /* we don't have to do anything on the last pass (6) */
+ if (row && row_info && pass < 6)
+ {
+ /* each pixel depth is handled seperately */
+ switch (row_info->pixel_depth)
+ {
+ case 1:
+ {
+ png_byte *sp;
+ png_byte *dp;
+ int shift;
+ int d;
+ int value;
+ png_uint_32 i;
+
+ dp = row;
+ d = 0;
+ shift = 7;
+ for (i = png_pass_start[pass];
+ i < row_info->width;
+ i += png_pass_inc[pass])
+ {
+ sp = row + (png_size_t)(i >> 3);
+ value = (int)(*sp >> (7 - (int)(i & 7))) & 0x1;
+ d |= (value << shift);
+
+ if (shift == 0)
+ {
+ shift = 7;
+ *dp++ = d;
+ d = 0;
+ }
+ else
+ shift--;
+
+ }
+ if (shift != 7)
+ *dp = d;
+ break;
+ }
+ case 2:
+ {
+ png_byte *sp;
+ png_byte *dp;
+ int shift;
+ int d;
+ int value;
+ png_uint_32 i;
+
+ dp = row;
+ shift = 6;
+ d = 0;
+ for (i = png_pass_start[pass];
+ i < row_info->width;
+ i += png_pass_inc[pass])
+ {
+ sp = row + (png_size_t)(i >> 2);
+ value = (*sp >> ((3 - (int)(i & 3)) << 1)) & 0x3;
+ d |= (value << shift);
+
+ if (shift == 0)
+ {
+ shift = 6;
+ *dp++ = d;
+ d = 0;
+ }
+ else
+ shift -= 2;
+ }
+ if (shift != 6)
+ *dp = d;
+ break;
+ }
+ case 4:
+ {
+ png_byte *sp;
+ png_byte *dp;
+ int shift;
+ int d;
+ int value;
+ png_uint_32 i;
+
+ dp = row;
+ shift = 4;
+ d = 0;
+ for (i = png_pass_start[pass];
+ i < row_info->width;
+ i += png_pass_inc[pass])
+ {
+ sp = row + (png_size_t)(i >> 1);
+ value = (*sp >> ((1 - (int)(i & 1)) << 2)) & 0xf;
+ d |= (value << shift);
+
+ if (shift == 0)
+ {
+ shift = 4;
+ *dp++ = d;
+ d = 0;
+ }
+ else
+ shift -= 4;
+ }
+ if (shift != 4)
+ *dp = d;
+ break;
+ }
+ default:
+ {
+ png_byte *sp;
+ png_byte *dp;
+ png_uint_32 i;
+ int pixel_bytes;
+
+ /* start at the beginning */
+ dp = row;
+ /* find out how many bytes each pixel takes up */
+ pixel_bytes = (row_info->pixel_depth >> 3);
+ /* loop through the row, only looking at the pixels that
+ matter */
+ for (i = png_pass_start[pass];
+ i < row_info->width;
+ i += png_pass_inc[pass])
+ {
+ /* find out where the original pixel is */
+ sp = row + (png_size_t)(i * pixel_bytes);
+ /* move the pixel */
+ if (dp != sp)
+ memcpy(dp, sp, pixel_bytes);
+ /* next pixel */
+ dp += pixel_bytes;
+ }
+ break;
+ }
+ }
+ /* set new row width */
+ row_info->width = (row_info->width +
+ png_pass_inc[pass] - 1 -
+ png_pass_start[pass]) /
+ png_pass_inc[pass];
+ row_info->rowbytes = ((row_info->width *
+ row_info->pixel_depth + 7) >> 3);
+
+ }
+}
+
+/* this filters the row. Both row and prev_row have space at the
+ first byte for the filter byte. */
+void
+png_write_filter_row(png_row_info *row_info, png_byte *row,
+ png_byte *prev_row)
+{
+ int minf, bpp;
+ png_uint_32 i, v;
+ png_uint_32 s, mins;
+ png_byte *rp, *pp, *cp, *lp;
+
+ /* find out how many bytes offset each pixel is */
+ bpp = (row_info->pixel_depth + 7) / 8;
+ if (bpp < 1)
+ bpp = 1;
+
+ /* the prediction method we use is to find which method provides
+ the smallest value when summing the abs of the distances from
+ zero using anything >= 128 as negitive numbers. */
+ for (i = 0, s = 0, rp = row + 1; i < row_info->rowbytes; i++, rp++)
+ {
+ v = *rp;
+ if (v < 128)
+ s += v;
+ else
+ s += 256 - (png_int_32)v;
+ }
+
+ mins = s;
+ minf = 0;
+
+ /* check sub filter */
+ for (i = 0, s = 0, rp = row + 1, lp = row + 1 - bpp;
+ i < row_info->rowbytes; i++, rp++, lp++)
+ {
+ if (i >= bpp)
+ v = (png_byte)(((int)*rp - (int)*lp) & 0xff);
+ else
+ v = *rp;
+
+ if (v < 128)
+ s += v;
+ else
+ s += 256 - v;
+ }
+
+ if (s < mins)
+ {
+ mins = s;
+ minf = 1;
+ }
+
+ /* check up filter */
+ for (i = 0, s = 0, rp = row + 1, pp = prev_row + 1;
+ i < row_info->rowbytes; i++, rp++, pp++)
+ {
+ v = (png_byte)(((int)*rp - (int)*pp) & 0xff);
+
+ if (v < 128)
+ s += v;
+ else
+ s += 256 - v;
+ }
+
+ if (s < mins)
+ {
+ mins = s;
+ minf = 2;
+ }
+
+ /* check avg filter */
+ for (i = 0, s = 0, rp = row + 1, pp = prev_row + 1, lp = row + 1 - bpp;
+ i < row_info->rowbytes; i++, rp++, pp++, lp++)
+ {
+ if (i >= bpp)
+ v = (png_byte)(((int)*rp - (((int)*pp + (int)*lp) / 2)) & 0xff);
+ else
+ v = (png_byte)(((int)*rp - ((int)*pp / 2)) & 0xff);
+
+ if (v < 128)
+ s += v;
+ else
+ s += 256 - v;
+ }
+
+ if (s < mins)
+ {
+ mins = s;
+ minf = 3;
+ }
+
+ /* check paeth filter */
+ for (i = 0, s = 0, rp = row + 1, pp = prev_row + 1, lp = row + 1 - bpp,
+ cp = prev_row + 1 - bpp;
+ i < row_info->rowbytes; i++, rp++, pp++, lp++, cp++)
+ {
+ int a, b, c, pa, pb, pc, p;
+
+ b = *pp;
+ if (i >= bpp)
+ {
+ c = *cp;
+ a = *lp;
+ }
+ else
+ {
+ a = c = 0;
+ }
+ p = a + b - c;
+ pa = abs(p - a);
+ pb = abs(p - b);
+ pc = abs(p - c);
+
+ if (pa <= pb && pa <= pc)
+ p = a;
+ else if (pb <= pc)
+ p = b;
+ else
+ p = c;
+
+ v = (png_byte)(((int)*rp - p) & 0xff);
+
+ if (v < 128)
+ s += v;
+ else
+ s += 256 - v;
+ }
+
+ if (s < mins)
+ {
+ mins = s;
+ minf = 4;
+ }
+
+ /* set filter byte */
+ row[0] = minf;
+
+ /* do filter */
+ switch (minf)
+ {
+ /* sub filter */
+ case 1:
+ for (i = bpp, rp = row + (png_size_t)row_info->rowbytes,
+ lp = row + (png_size_t)row_info->rowbytes - bpp;
+ i < row_info->rowbytes; i++, rp--, lp--)
+ {
+ *rp = (png_byte)(((int)*rp - (int)*lp) & 0xff);
+ }
+ break;
+ /* up filter */
+ case 2:
+ for (i = 0, rp = row + (png_size_t)row_info->rowbytes,
+ pp = prev_row + (png_size_t)row_info->rowbytes;
+ i < row_info->rowbytes; i++, rp--, pp--)
+ {
+ *rp = (png_byte)(((int)*rp - (int)*pp) & 0xff);
+ }
+ break;
+ /* avg filter */
+ case 3:
+ for (i = row_info->rowbytes,
+ rp = row + (png_size_t)row_info->rowbytes,
+ pp = prev_row + (png_size_t)row_info->rowbytes,
+ lp = row + (png_size_t)row_info->rowbytes - bpp;
+ i > bpp; i--, rp--, lp--, pp--)
+ {
+ *rp = (png_byte)(((int)*rp - (((int)*lp + (int)*pp) /
+ 2)) & 0xff);
+ }
+ for (; i > 0; i--, rp--, pp--)
+ {
+ *rp = (png_byte)(((int)*rp - ((int)*pp / 2)) & 0xff);
+ }
+ break;
+ /* paeth filter */
+ case 4:
+ for (i = row_info->rowbytes,
+ rp = row + (png_size_t)row_info->rowbytes,
+ pp = prev_row + (png_size_t)row_info->rowbytes,
+ lp = row + (png_size_t)row_info->rowbytes - bpp,
+ cp = prev_row + (png_size_t)row_info->rowbytes - bpp;
+ i > 0; i--, rp--, lp--, pp--, cp--)
+ {
+ int a, b, c, pa, pb, pc, p;
+
+ b = *pp;
+ if (i > bpp)
+ {
+ c = *cp;
+ a = *lp;
+ }
+ else
+ {
+ a = c = 0;
+ }
+ p = a + b - c;
+ pa = abs(p - a);
+ pb = abs(p - b);
+ pc = abs(p - c);
+
+ if (pa <= pb && pa <= pc)
+ p = a;
+ else if (pb <= pc)
+ p = b;
+ else
+ p = c;
+
+ *rp = (png_byte)(((int)*rp - p) & 0xff);
+ }
+ break;
+ }
+}