196    /* The oFFs chunk gives the offset in "offset_unit_type" units rightwards
 197     * and downwards from the top-left corner of the display, page, or other
 198     * application-specific co-ordinate space.  See the PNG_OFFSET_ defines
 199     * below for the unit types.  Valid if (valid & PNG_INFO_oFFs) non-zero.
 200     */
 201    png_int_32 x_offset; /* x offset on page */
 202    png_int_32 y_offset; /* y offset on page */
 203    png_byte offset_unit_type; /* offset units type */
 204 #endif
 205 
 206 #ifdef PNG_pHYs_SUPPORTED
 207    /* The pHYs chunk gives the physical pixel density of the image for
 208     * display or printing in "phys_unit_type" units (see PNG_RESOLUTION_
 209     * defines below).  Data is valid if (valid & PNG_INFO_pHYs) is non-zero.
 210     */
 211    png_uint_32 x_pixels_per_unit; /* horizontal pixel density */
 212    png_uint_32 y_pixels_per_unit; /* vertical pixel density */
 213    png_byte phys_unit_type; /* resolution type (see PNG_RESOLUTION_ below) */
 214 #endif
 215 








 216 #ifdef PNG_hIST_SUPPORTED
 217    /* The hIST chunk contains the relative frequency or importance of the
 218     * various palette entries, so that a viewer can intelligently select a
 219     * reduced-color palette, if required.  Data is an array of "num_palette"
 220     * values in the range [0,65535]. Data valid if (valid & PNG_INFO_hIST)
 221     * is non-zero.
 222     */
 223    png_uint_16p hist;
 224 #endif
 225 
 226 #ifdef PNG_pCAL_SUPPORTED
 227    /* The pCAL chunk describes a transformation between the stored pixel
 228     * values and original physical data values used to create the image.
 229     * The integer range [0, 2^bit_depth - 1] maps to the floating-point
 230     * range given by [pcal_X0, pcal_X1], and are further transformed by a
 231     * (possibly non-linear) transformation function given by "pcal_type"
 232     * and "pcal_params" into "pcal_units".  Please see the PNG_EQUATION_
 233     * defines below, and the PNG-Group's PNG extensions document for a
 234     * complete description of the transformations and how they should be
 235     * implemented, and for a description of the ASCII parameter strings.

 196    /* The oFFs chunk gives the offset in "offset_unit_type" units rightwards
 197     * and downwards from the top-left corner of the display, page, or other
 198     * application-specific co-ordinate space.  See the PNG_OFFSET_ defines
 199     * below for the unit types.  Valid if (valid & PNG_INFO_oFFs) non-zero.
 200     */
 201    png_int_32 x_offset; /* x offset on page */
 202    png_int_32 y_offset; /* y offset on page */
 203    png_byte offset_unit_type; /* offset units type */
 204 #endif
 205 
 206 #ifdef PNG_pHYs_SUPPORTED
 207    /* The pHYs chunk gives the physical pixel density of the image for
 208     * display or printing in "phys_unit_type" units (see PNG_RESOLUTION_
 209     * defines below).  Data is valid if (valid & PNG_INFO_pHYs) is non-zero.
 210     */
 211    png_uint_32 x_pixels_per_unit; /* horizontal pixel density */
 212    png_uint_32 y_pixels_per_unit; /* vertical pixel density */
 213    png_byte phys_unit_type; /* resolution type (see PNG_RESOLUTION_ below) */
 214 #endif
 215 
 216 #ifdef PNG_eXIf_SUPPORTED
 217    int num_exif;  /* Added at libpng-1.6.31 */
 218    png_bytep exif;
 219 # ifdef PNG_READ_eXIf_SUPPORTED
 220    png_bytep eXIf_buf;  /* Added at libpng-1.6.32 */
 221 # endif
 222 #endif
 223 
 224 #ifdef PNG_hIST_SUPPORTED
 225    /* The hIST chunk contains the relative frequency or importance of the
 226     * various palette entries, so that a viewer can intelligently select a
 227     * reduced-color palette, if required.  Data is an array of "num_palette"
 228     * values in the range [0,65535]. Data valid if (valid & PNG_INFO_hIST)
 229     * is non-zero.
 230     */
 231    png_uint_16p hist;
 232 #endif
 233 
 234 #ifdef PNG_pCAL_SUPPORTED
 235    /* The pCAL chunk describes a transformation between the stored pixel
 236     * values and original physical data values used to create the image.
 237     * The integer range [0, 2^bit_depth - 1] maps to the floating-point
 238     * range given by [pcal_X0, pcal_X1], and are further transformed by a
 239     * (possibly non-linear) transformation function given by "pcal_type"
 240     * and "pcal_params" into "pcal_units".  Please see the PNG_EQUATION_
 241     * defines below, and the PNG-Group's PNG extensions document for a
 242     * complete description of the transformations and how they should be
 243     * implemented, and for a description of the ASCII parameter strings.