Imager::APIRef(3pm)

NAME
Imager::APIRef - Imager's C API - reference.

SYNOPSIS
  i_color color;
  color.rgba.r = 255; color.rgba.g = 0; color.rgba.b = 255;

  # Blit tools

  # Data Types
  i_img *img;
  i_color black;
  black.rgba.r = black.rgba.g = black.rgba.b = black.rgba.a = 0;
  i_fill_t *fill;
  i_img_dim x, y;
  printf("left %" i_DF "\n", i_DFc(x));
  printf("point (" i_DFp ")\n", i_DFcp(x, y));

  # Drawing
  i_arc(im, 50, 50, 20, 45, 135, &color);
  i_arc_cfill(im, 50, 50, 35, 90, 135, fill);
  i_arc_aa(im, 50, 50, 35, 90, 135, &color);
  i_arc_aa_cfill(im, 50, 50, 35, 90, 135, fill);
  i_circle_aa(im, 50, 50, 45, &color);
  i_box(im, 0, 0, im->xsize-1, im->ysize-1, &color).
  i_box_filled(im, 0, 0, im->xsize-1, im->ysize-1, &color);
  i_box_cfill(im, 0, 0, im->xsize-1, im->ysize-1, fill);
  i_flood_fill(im, 50, 50, &color);
  i_flood_cfill(im, 50, 50, fill);
  i_flood_fill_border(im, 50, 50, &color, &border);
  i_flood_cfill_border(im, 50, 50, fill, border);

  # Error handling
  im_clear_error(aIMCTX);
  i_clear_error();
  i_push_error(0, "Yep, it's broken");
  i_push_error(errno, "Error writing");
  im_push_error(aIMCTX, 0, "Something is wrong");
  va_args args;
  va_start(args, lastarg);
  im_push_errorvf(ctx, code, format, args);
  i_push_errorf(errno, "Cannot open file %s: %d", filename, errno);
  im_push_errorf(aIMCTX, errno, "Cannot open file %s: %d", filename, errno);

  # Files
  im_set_image_file_limits(aIMCTX, 500, 500, 1000000);
  i_set_image_file_limits(500, 500, 1000000);
  im_get_image_file_limits(aIMCTX, &width, &height, &bytes)
  i_get_image_file_limits(&width, &height, &bytes)
  im_int_check_image_file_limits(aIMCTX, width, height, channels, sizeof(i_sample_t))
  i_int_check_image_file_limits(width, height, channels, sizeof(i_sample_t))

  # Fills
  i_fill_t *fill = i_new_fill_solidf(&fcolor, combine);
  i_fill_t *fill = i_new_fill_solid(&color, combine);
  i_fill_t *fill = i_new_fill_hatch(&fg_color, &bg_color, combine, hatch, custom_hatch, dx, dy);
  i_fill_t *fill = i_new_fill_hatchf(&fg_fcolor, &bg_fcolor, combine, hatch, custom_hatch, dx, dy);
  i_fill_t *fill = i_new_fill_image(src_img, matrix, x_offset, y_offset, combine);
  fill = i_new_fill_fount(0, 0, 100, 100, i_ft_linear, i_ft_linear,
                          i_fr_triangle, 0, i_fts_grid, 9, 1, segs);
  i_fill_destroy(fill);

  # I/O Layers
  ssize_t count = i_io_peekn(ig, buffer, sizeof(buffer));
  ssize_t result = i_io_write(io, buffer, size)
  char buffer[BUFSIZ]
  ssize_t len = i_io_gets(buffer, sizeof(buffer), '\n');
  io_glue_destroy(ig);

  # Image

  # Image creation/destruction
  i_img *img = i_sametype(src, width, height);
  i_img *img = i_sametype_chans(src, width, height, channels);
  i_img *img = im_img_16_new(aIMCTX, width, height, channels);
  i_img *img = i_img_16_new(width, height, channels);
  i_img *img = im_img_8_new(aIMCTX, width, height, channels);
  i_img *img = i_img_8_new(width, height, channels);
  i_img *img = im_img_double_new(aIMCTX, width, height, channels);
  i_img *img = i_img_double_new(width, height, channels);
  i_img *img = im_img_pal_new(aIMCTX, width, height, channels, max_palette_size)
  i_img *img = i_img_pal_new(width, height, channels, max_palette_size)
  i_img_destroy(img)

  # Image Implementation
  i_img *im = im_img_alloc(aIMCTX);
  i_img *im = i_img_alloc();
  im_img_init(aIMCTX, im);
  i_img_init(im);

  # Image Information
  // only channel 0 writable
  i_img_setmask(img, 0x01);
  int mask = i_img_getmask(img);
  int channels = i_img_getchannels(img);
  i_img_dim width = i_img_get_width(im);
  i_img_dim height = i_img_get_height(im);

  # Image quantization

  # Logging

  # Mutex functions
  i_mutex_t m = i_mutex_new();
  i_mutex_destroy(m);
  i_mutex_lock(m);
  i_mutex_unlock(m);

  # Paletted images

  # Tags
  i_tags_set(&img->tags, "i_comment", -1);
  i_tags_setn(&img->tags, "i_xres", 204);
  i_tags_setn(&img->tags, "i_yres", 196);

DESCRIPTION

  Blit tools

i_render_color(r, x, y, width, source, color)
    Render the given color with the coverage specified by "source[0]" to "source[width-1]".

    Renders in normal combine mode.

i_render_delete(r)
    Release an "i_render" object.

i_render_fill(r, x, y, width, source, fill)
    Render the given fill with the coverage in "source[0]" through "source[width-1]".

i_render_line(r, x, y, width, source, fill)
    Render the given fill with the coverage in "source[0]" through "source[width-1]".

i_render_linef(r, x, y, width, source, fill)
    Render the given fill with the coverage in "source[0]" through "source[width-1]".

i_render_new(im, width)
    Allocate a new "i_render" object and initialize it.

  Data Types

i_img
      i_img *img;

    This is Imager's image type.

    It contains the following members:

    •   "channels" - the number of channels in the image

    •   "xsize", "ysize" - the width and height of the image in pixels

    •   "bytes" - the number of bytes used to store the image data. Undefined where virtual is non-zero.

    •   "ch_mask" - a mask of writable channels. eg. if this is 6 then only channels 1 and 2 are writable. There may be bits set for which there are no channels in the image.

    •   "bits" - the number of bits stored per sample. Should be one of i_8_bits, i_16_bits, i_double_bits.

    •   "type" - either i_direct_type for direct color images, or i_palette_type for paletted images.

    •   "virtual" - if zero then this image is-self contained. If non-zero then this image could be an interface to some other implementation.

    •   "idata" - the image data. This should not be directly accessed. A new image implementation can use this to store its image data. i_img_destroy() will myfree() this pointer if it's non-null.

    •   "tags" - a structure storing the image's tags. This should only be accessed via the i_tags_*() functions.

    •   "ext_data" - a pointer for use internal to an image implementation. This should be freed by the image's destroy handler.

    •   "im_data" - data internal to Imager. This is initialized by i_img_init().

    •   i_f_ppix, i_f_ppixf, i_f_plin, i_f_plinf, i_f_gpix, i_f_gpixf, i_f_glin, i_f_glinf, i_f_gsamp, i_f_gampf - implementations for each of the required image functions. An image implementation should initialize these between calling i_img_alloc() and i_img_init().

    •   i_f_gpal, i_f_ppal, i_f_addcolors, i_f_getcolors, i_f_colorcount, i_f_maxcolors, i_f_findcolor, i_f_setcolors - implementations for each paletted image function.

    •   i_f_destroy - custom image destruction function. This should be used to release memory if necessary.

    •   i_f_gsamp_bits - implements i_gsamp_bits() for this image.

    •   i_f_psamp_bits - implements i_psamp_bits() for this image.

    •   i_f_psamp - implements psamp() for this image.

    •   i_f_psampf - implements psamp() for this image.

    •   "im_data" - image specific data internal to Imager.

    •   "context" - the Imager API context this image belongs to.

i_color
      i_color black;
      black.rgba.r = black.rgba.g = black.rgba.b = black.rgba.a = 0;

    Type for 8-bit/sample color.

    Samples as per;

      i_color c;

    i_color is a union of:

    •   gray - contains a single element gray_color, eg. "c.gray.gray_color"

    •   "rgb" - contains three elements "r", "g", "b", eg. "c.rgb.r"

    •   "rgba" - contains four elements "r", "g", "b", "a", eg. "c.rgba.a"

    •   "cmyk" - contains four elements "c", "m", "y", "k", eg. "c.cmyk.y". Note that Imager never uses CMYK colors except when reading/writing files.

    •   channels - an array of four channels, eg "c.channels[2]".

i_fcolor
    This is the double/sample color type.

    Its layout exactly corresponds to i_color.

i_fill_t
      i_fill_t *fill;

    This is the "abstract" base type for Imager's fill types.

    Unless you're implementing a new fill type you'll typically treat this as an opaque type.

i_img_dim
      i_img_dim x, y;

    A signed integer type that represents an image dimension or ordinate.

    May be larger than int on some platforms.

i_DF
      printf("left %" i_DF "\n", i_DFc(x));

    This is a constant string that can be used with functions like printf() to format i_img_dim values after they're been cast with i_DFc().

    Does not include the leading "%".

i_DFc
    Cast an "i_img_dim" value to a type for use with the i_DF format string.

i_DFcp
    Casts two "i_img_dim" values for use with the i_DF (or i_DFp) format.

i_DFp
      printf("point (" i_DFp ")\n", i_DFcp(x, y));

    Format a pair of "i_img_dim" values. This format string does include the leading "%".

  Drawing

i_arc(im, x, y, rad, d1, d2, color)
      i_arc(im, 50, 50, 20, 45, 135, &color);

    Fills an arc centered at (x,y) with radius rad covering the range of angles in degrees from d1 to d2, with the color.

i_arc_aa(im, x, y, rad, d1, d2, color)
      i_arc_aa(im, 50, 50, 35, 90, 135, &color);

    Anti-alias fills an arc centered at (x,y) with radius rad covering the range of angles in degrees from d1 to d2, with the color.

i_arc_aa_cfill(im, x, y, rad, d1, d2, fill)
      i_arc_aa_cfill(im, 50, 50, 35, 90, 135, fill);

    Anti-alias fills an arc centered at (x,y) with radius rad covering the range of angles in degrees from d1 to d2, with the fill object.

i_arc_cfill(im, x, y, rad, d1, d2, fill)
      i_arc_cfill(im, 50, 50, 35, 90, 135, fill);

    Fills an arc centered at (x,y) with radius rad covering the range of angles in degrees from d1 to d2, with the fill object.

i_box(im, x1, y1, x2, y2, color)
      i_box(im, 0, 0, im->xsize-1, im->ysize-1, &color).

    Outlines the box from (x1,y1) to (x2,y2) inclusive with color.

i_box_cfill(im, x1, y1, x2, y2, fill)
      i_box_cfill(im, 0, 0, im->xsize-1, im->ysize-1, fill);

    Fills the box from (x1,y1) to (x2,y2) inclusive with fill.

i_box_filled(im, x1, y1, x2, y2, color)
      i_box_filled(im, 0, 0, im->xsize-1, im->ysize-1, &color);

    Fills the box from (x1,y1) to (x2,y2) inclusive with color.

i_circle_aa(im, x, y, rad, color)
      i_circle_aa(im, 50, 50, 45, &color);

    Anti-alias fills a circle centered at (x,y) for radius rad with color.

i_flood_cfill("im", "seedx", "seedy", "fill")
      i_flood_cfill(im, 50, 50, fill);

    Flood fills the 4-connected region starting from the point ("seedx", "seedy") with "fill".

    Returns false if ("seedx", "seedy") are outside the image.

i_flood_cfill_border("im", "seedx", "seedy", "fill", "border")
      i_flood_cfill_border(im, 50, 50, fill, border);

    Flood fills the 4-connected region starting from the point ("seedx", "seedy") with "fill", the fill stops when it reaches pixels of color "border".

    Returns false if ("seedx", "seedy") are outside the image.

i_flood_fill("im", "seedx", "seedy", "color")
      i_flood_fill(im, 50, 50, &color);

    Flood fills the 4-connected region starting from the point ("seedx", "seedy") with color.

    Returns false if ("seedx", "seedy") are outside the image.

i_flood_fill_border("im", "seedx", "seedy", "color", "border")
      i_flood_fill_border(im, 50, 50, &color, &border);

    Flood fills the 4-connected region starting from the point ("seedx", "seedy") with "color", fill stops when the fill reaches a pixels with color "border".

    Returns false if ("seedx", "seedy") are outside the image.

i_glin(im, l, r, y, colors)
    Retrieves (r-l) pixels starting from (l,y) into colors.

    Returns the number of pixels retrieved.

i_glinf(im, l, r, y, colors)
    Retrieves (r-l) pixels starting from (l,y) into colors as floating point colors.

    Returns the number of pixels retrieved.

i_gpal(im, left, right, y, indexes)
    Reads palette indexes for the horizontal line (left, y) to (right-1, y) into "indexes".

    Returns the number of indexes read.

    Always returns 0 for direct color images.

i_gpix(im, "x", "y", "color")
    Retrieves the "color" of the pixel (x,y).

    Returns 0 if the pixel was retrieved, or -1 if not.

i_gpixf(im, "x", "y", "fcolor")
    Retrieves the color of the pixel (x,y) as a floating point color into "fcolor".

    Returns 0 if the pixel was retrieved, or -1 if not.

i_gsamp(im, left, right, y, samples, channels, channel_count)
    Reads sample values from "im" for the horizontal line (left, y) to (right-1,y) for the channels specified by "channels", an array of int with "channel_count" elements.

    If channels is NULL then the first channels_count channels are retrieved for each pixel.

    Returns the number of samples read (which should be (right-left) * channel_count)

i_gsamp_bg(im, l, r, y, samples, out_channels, background)
    Like "i_gsampf()" but applies the source image color over a supplied background color.

    This is intended for output to image formats that don't support alpha channels.

i_gsamp_bits(im, left, right, y, samples, channels, channel_count, bits)
    Reads integer samples scaled to "bits" bits of precision into the "unsigned int" array "samples".

    Expect this to be slow unless "bits == im->bits".

    Returns the number of samples copied, or -1 on error.

    Not all image types implement this method.

    Pushes errors, but does not call "i_clear_error()".

i_gsampf(im, left, right, y, samples, channels, channel_count)
    Reads floating point sample values from "im" for the horizontal line (left, y) to (right-1,y) for the channels specified by "channels", an array of int with channel_count elements.

    If "channels" is NULL then the first "channel_count" channels are retrieved for each pixel.

    Returns the number of samples read (which should be ("right"-"left") * "channel_count")

i_gsampf_bg(im, l, r, y, samples, out_channels, background)
    Like "i_gsampf()" but applies the source image color over a supplied background color.

    This is intended for output to image formats that don't support alpha channels.

i_line("im", "x1", "y1", "x2", "y2", "color", "endp")
    Draw a line to image using Bresenham's line drawing algorithm

       im    - image to draw to
       x1    - starting x coordinate
       y1    - starting x coordinate
       x2    - starting x coordinate
       y2    - starting x coordinate
       color - color to write to image
       endp  - endpoint flag (boolean)

i_line_aa("im", "x1", "x2", "y1", "y2", "color", "endp")
    Anti-alias draws a line from (x1,y1) to (x2, y2) in color.

    The point (x2, y2) is drawn only if "endp" is set.

i_plin(im, l, r, y, colors)
    Sets (r-l) pixels starting from (l,y) using (r-l) values from colors.

    Returns the number of pixels set.

i_plinf(im, "left", "right", "fcolors")
    Sets (right-left) pixels starting from (left,y) using (right-left) floating point colors from "fcolors".

    Returns the number of pixels set.

i_ppal(im, left, right, y, indexes)
    Writes palette indexes for the horizontal line (left, y) to (right-1, y) from "indexes".

    Returns the number of indexes written.

    Always returns 0 for direct color images.

i_ppix(im, x, y, color)
    Sets the pixel at (x,y) to color.

    Returns 0 if the pixel was drawn, or -1 if not.

    Does no alpha blending, just copies the channels from the supplied color to the image.

i_ppixf(im, "x", "y", "fcolor")
    Sets the pixel at ("x","y") to the floating point color "fcolor".

    Returns 0 if the pixel was drawn, or -1 if not.

    Does no alpha blending, just copies the channels from the supplied color to the image.

i_psamp(im, left, right, y, samples, channels, channel_count)
    Writes sample values from "samples" to "im" for the horizontal line (left, y) to (right-1, y) inclusive for the channels specified by "channels", an array of "int" with "channel_count" elements.

    If "channels" is "NULL" then the first "channels_count" channels are written to for each pixel.

    Returns the number of samples written, which should be (right - left) * channel_count. If a channel not in the image is in channels, left is negative, left is outside the image or y is outside the image, returns -1 and pushes an error.

i_psamp_bits(im, left, right, y, samples, channels, channel_count, bits)
    Writes integer samples scaled to "bits" bits of precision from the "unsigned int" array "samples".

    Expect this to be slow unless "bits == im->bits".

    Returns the number of samples copied, or -1 on error.

    Not all image types implement this method.

    Pushes errors, but does not call "i_clear_error()".

i_psampf(im, left, right, y, samples, channels, channel_count)
    Writes floating point sample values from "samples" to "im" for the horizontal line (left, y) to (right-1, y) inclusive for the channels specified by "channels", an array of "int" with "channel_count" elements.

    If "channels" is "NULL" then the first "channels_count" channels are written to for each pixel.

    Returns the number of samples written, which should be (right - left) * channel_count. If a channel not in the image is in channels, left is negative, left is outside the image or y is outside the image, returns -1 and pushes an error.

  Error handling

i_push_errorf(int code, char const *fmt, ...)
      i_push_errorf(errno, "Cannot open file %s: %d", filename, errno);

    A version of i_push_error() that does printf() like formatting.

    Does not support perl specific format codes.

im_clear_error(ctx)
      im_clear_error(aIMCTX);
      i_clear_error();

    Clears the error stack.

    Called by any Imager function before doing any other processing.

    Also callable as "i_clear_error()".

im_push_error(ctx, code, message)
      i_push_error(0, "Yep, it's broken");
      i_push_error(errno, "Error writing");
      im_push_error(aIMCTX, 0, "Something is wrong");

    Called by an Imager function to push an error message onto the stack.

    No message is pushed if the stack is full (since this means someone forgot to call i_clear_error(), or that a function that doesn't do error handling is calling function that does.).

im_push_errorf(ctx, code, char const *fmt, ...)
      im_push_errorf(aIMCTX, errno, "Cannot open file %s: %d", filename, errno);

    A version of im_push_error() that does printf() like formatting.

    Does not support perl specific format codes.

im_push_errorvf(ctx, code, format, args)
      va_args args;
      va_start(args, lastarg);
      im_push_errorvf(ctx, code, format, args);

    Intended for use by higher level functions, takes a varargs pointer and a format to produce the finally pushed error message.

    Does not support perl specific format codes.

    Also callable as "i_push_errorvf(code, format, args)"

  Files

i_get_file_background(im, &bg)
    Retrieve the file write background color tag from the image.

    If not present, "bg" is set to black.

    Returns 1 if the "i_background" tag was found and valid.

i_get_file_backgroundf(im, &bg)
    Retrieve the file write background color tag from the image as a floating point color.

    Implemented in terms of i_get_file_background().

    If not present, "bg" is set to black.

    Returns 1 if the "i_background" tag was found and valid.

im_get_image_file_limits(ctx, &width, &height, &bytes)
      im_get_image_file_limits(aIMCTX, &width, &height, &bytes)
      i_get_image_file_limits(&width, &height, &bytes)

    Retrieves the file limits set by i_set_image_file_limits().

    •   i_img_dim *width, *height - the maximum width and height of the image.

    •   size_t *bytes - size in memory of the image in bytes.

    Also callable as "i_get_image_file_limits(&width, &height, &bytes)".

im_int_check_image_file_limits(width, height, channels, sample_size)
      im_int_check_image_file_limits(aIMCTX, width, height, channels, sizeof(i_sample_t))
      i_int_check_image_file_limits(width, height, channels, sizeof(i_sample_t))

    Checks the size of a file in memory against the configured image file limits.

    This also range checks the values to those permitted by Imager and checks for overflows in calculating the size.

    Returns non-zero if the file is within limits.

    This function is intended to be called by image file read functions.

    Also callable as "i_int_check_image_file_limits(width, height, channels, sizeof(i_sample_t)".

im_set_image_file_limits(ctx, width, height, bytes)
      im_set_image_file_limits(aIMCTX, 500, 500, 1000000);
      i_set_image_file_limits(500, 500, 1000000);

    Set limits on the sizes of images read by Imager.

    Setting a limit to 0 means that limit is ignored.

    Negative limits result in failure.

    Parameters:

    •   i_img_dim width, height - maximum width and height.

    •   size_t bytes - maximum size in memory in bytes. A value of zero sets this limit to one gigabyte.

    Returns non-zero on success.

    Also callable as "i_set_image_file_limits(width, height, bytes)".

  Fills

i_new_fill_fount("xa", "ya", "xb", "yb", "type", "repeat", "combine", "super_sample", "ssample_param", "count", "segs")
      fill = i_new_fill_fount(0, 0, 100, 100, i_ft_linear, i_ft_linear,
                              i_fr_triangle, 0, i_fts_grid, 9, 1, segs);

    Creates a new general fill which fills with a fountain fill.

i_new_fill_hatch("fg", "bg", "combine", "hatch", "cust_hatch", "dx", "dy")
      i_fill_t *fill = i_new_fill_hatch(&fg_color, &bg_color, combine, hatch, custom_hatch, dx, dy);

    Creates a new hatched fill with the "fg" color used for the 1 bits in the hatch and "bg" for the 0 bits. If "combine" is non-zero alpha values will be combined.

    If "cust_hatch" is non-NULL it should be a pointer to 8 bytes of the hash definition, with the high-bits to the left.

    If "cust_hatch" is NULL then one of the standard hatches is used.

    ("dx", "dy") are an offset into the hatch which can be used to hatch adjoining areas out of alignment, or to align the origin of a hatch with the side of a filled area.

i_new_fill_hatchf("fg", "bg", "combine", "hatch", "cust_hatch", "dx", "dy")
      i_fill_t *fill = i_new_fill_hatchf(&fg_fcolor, &bg_fcolor, combine, hatch, custom_hatch, dx, dy);

    Creates a new hatched fill with the "fg" color used for the 1 bits in the hatch and "bg" for the 0 bits. If "combine" is non-zero alpha values will be combined.

    If "cust_hatch" is non-NULL it should be a pointer to 8 bytes of the hash definition, with the high-bits to the left.

    If "cust_hatch" is NULL then one of the standard hatches is used.

    ("dx", "dy") are an offset into the hatch which can be used to hatch adjoining areas out of alignment, or to align the origin of a hatch with the side of a filled area.

i_new_fill_image("im", "matrix", "xoff", "yoff", "combine")
      i_fill_t *fill = i_new_fill_image(src_img, matrix, x_offset, y_offset, combine);

    Create an image based fill.

    matrix is an array of 9 doubles representing a transformation matrix.

    "xoff" and "yoff" are the offset into the image to start filling from.

i_new_fill_solid(color, combine)
      i_fill_t *fill = i_new_fill_solid(&color, combine);

    Create a solid fill based on an 8-bit color.

    If combine is non-zero then alpha values will be combined.

i_new_fill_solidf(color, combine)
      i_fill_t *fill = i_new_fill_solidf(&fcolor, combine);

    Create a solid fill based on a float color.

    If combine is non-zero then alpha values will be combined.

i_fill_destroy(fill)
      i_fill_destroy(fill);

    Call to destroy any fill object.

  I/O Layers

im_io_new_bufchain(ctx)
    Returns a new io_glue object that has the 'empty' source and but can be written to and read from later (like a pseudo file).

    Also callable as "io_new_bufchain()".

im_io_new_buffer(ctx, data, length)
    Returns a new io_glue object that has the source defined as reading from specified buffer. Note that the buffer is not copied.

       ctx - an Imager context object
       data - buffer to read from
       length - length of buffer

    Also callable as "io_new_buffer(data, length".

im_io_new_cb(ctx, p, read_cb, write_cb, seek_cb, close_cb, destroy_cb)
    Create a new I/O layer object that calls your supplied callbacks.

    In general the callbacks should behave like the corresponding POSIX primitives.

    •   "read_cb"(p, buffer, length) should read up to "length" bytes into "buffer" and return the number of bytes read. At end of file, return 0. On error, return -1.

    •   "write_cb"(p, buffer, length) should write up to "length" bytes from "buffer" and return the number of bytes written. A return value <= 0 will be treated as an error.

    •   "seekcb"(p, offset, whence) should seek and return the new offset.

    •   "close_cb"(p) should return 0 on success, -1 on failure.

    •   "destroy_cb"(p) should release any memory specific to your callback handlers.

    Also callable as "io_new_cb(p, readcb, writecb, seekcb, closecb, destroycb)".

im_io_new_fd(ctx, file)
    Returns a new io_glue object that has the source defined as reading from specified file descriptor. Note that the interface to receiving data from the io_glue callbacks hasn't been done yet.

      ctx - and Imager context object
      file - file descriptor to read/write from

    Also callable as "io_new_fd(file)".

i_io_close(io)
    Flush any pending output and perform the close action for the stream.

    Returns 0 on success.

i_io_flush(io)
    Flush any buffered output.

    Returns true on success,

i_io_getc(ig)
    A macro to read a single byte from a buffered I/O glue object.

    Returns EOF on failure, or a byte.

i_io_gets(ig, buffer, size, end_of_line)
      char buffer[BUFSIZ]
      ssize_t len = i_io_gets(buffer, sizeof(buffer), '\n');

    Read up to "size"-1 bytes from the stream "ig" into "buffer".

    If the byte "end_of_line" is seen then no further bytes will be read.

    Returns the number of bytes read.

    Always "NUL" terminates the buffer.

i_io_peekc(ig)
    Read the next character from the stream without advancing the stream.

    On error or end of file, return EOF.

    For unbuffered streams a single character buffer will be setup.

i_io_peekn(ig, buffer, size)
      ssize_t count = i_io_peekn(ig, buffer, sizeof(buffer));

    Buffer at least "size" (at most "ig->buf_size" bytes of data from the stream and return "size" bytes of it to the caller in "buffer".

    This ignores the buffered state of the stream, and will always setup buffering if needed.

    If no "type" parameter is provided to Imager::read() or Imager::read_multi(), Imager will call "i_io_peekn()" when probing for the file format.

    Returns -1 on error, 0 if there is no data before EOF, or the number of bytes read into "buffer".

i_io_putc(ig, c)
    Write a single character to the stream.

    On success return c, on error returns EOF

i_io_read(io, buffer, size)
    Read up to "size" bytes from the stream "io" into "buffer".

    Returns the number of bytes read. Returns 0 on end of file. Returns -1 on error.

i_io_seek(io, offset, whence)
    Seek within the stream.

    Acts like perl's seek.

i_io_set_buffered(io, buffered)
    Set the buffering mode of the stream.

    If you switch buffering off on a stream with buffering on:

    •   any buffered output will be flushed.

    •   any existing buffered input will be consumed before reads become unbuffered.

    Returns true on success. This may fail if any buffered output cannot be flushed.

i_io_write(io, buffer, size)
      ssize_t result = i_io_write(io, buffer, size)

    Write to the given I/O stream.

    Returns the number of bytes written.

io_slurp(ig, c)
    Takes the source that the io_glue is bound to and allocates space for a return buffer and returns the entire content in a single buffer. Note: This only works for io_glue objects created by io_new_bufchain(). It is useful for saving to scalars and such.

       ig - io_glue object
       c  - pointer to a pointer to where data should be copied to

      char *data;
      size_t size = io_slurp(ig, &data);
      ... do something with the data ...
      myfree(data);

    io_slurp() will abort the program if the supplied I/O layer is not from io_new_bufchain().

io_glue_destroy(ig)
      io_glue_destroy(ig);

    Destroy an io_glue objects. Should clean up all related buffers.

       ig - io_glue object to destroy.

  Image

i_copy(source)
    Creates a new image that is a copy of the image "source".

    Tags are not copied, only the image data.

    Returns: i_img *

i_copyto("dest", "src", "x1", "y1", "x2", "y2", "tx", "ty")
    Copies image data from the area ("x1","y1")-["x2","y2"] in the source image to a rectangle the same size with it's top-left corner at ("tx","ty") in the destination image.

    If "x1" > "x2" or "y1" > "y2" then the corresponding co-ordinates are swapped.

i_copyto_trans("im", "src", "x1", "y1", "x2", "y2", "tx", "ty", "trans")
    ("x1","y1") ("x2","y2") specifies the region to copy (in the source coordinates) ("tx","ty") specifies the upper left corner for the target image. pass NULL in "trans" for non transparent i_colors.

i_img_info(im, info)
    Return image information

       im - Image pointer
       info - pointer to array to return data

    info is an array of 4 integers with the following values:

     info[0] - width
     info[1] - height
     info[2] - channels
     info[3] - channel mask

i_rubthru("im", "src", "tx", "ty", "src_minx", "src_miny", "src_maxx", "src_maxy")
    Takes the sub image "src"["src_minx", "src_maxx")["src_miny", "src_maxy")> and overlays it at ("tx","ty") on the image object.

    The alpha channel of each pixel in "src" is used to control how much the existing color in "im" is replaced, if it is 255 then the color is completely replaced, if it is 0 then the original color is left unmodified.

  Image creation/destruction

i_sametype("im", "xsize", "ysize")
      i_img *img = i_sametype(src, width, height);

    Returns an image of the same type (sample size, channels, paletted/direct).

    For paletted images the palette is copied from the source.

i_sametype_chans("im", "xsize", "ysize", "channels")
      i_img *img = i_sametype_chans(src, width, height, channels);

    Returns an image of the same type (sample size).

    For paletted images the equivalent direct type is returned.

im_img_16_new(ctx, x, y, ch)
      i_img *img = im_img_16_new(aIMCTX, width, height, channels);
      i_img *img = i_img_16_new(width, height, channels);

    Create a new 16-bit/sample image.

    Returns the image on success, or NULL on failure.

    Also callable as "i_img_16_new(x, y, ch)"

im_img_8_new(ctx, x, y, ch)
      i_img *img = im_img_8_new(aIMCTX, width, height, channels);
      i_img *img = i_img_8_new(width, height, channels);

    Creates a new image object x pixels wide, and y pixels high with ch channels.

im_img_double_new(ctx, x, y, ch)
      i_img *img = im_img_double_new(aIMCTX, width, height, channels);
      i_img *img = i_img_double_new(width, height, channels);

    Creates a new double per sample image.

    Also callable as "i_img_double_new(width, height, channels)".

im_img_pal_new(ctx, "x", "y", "channels", "maxpal")
      i_img *img = im_img_pal_new(aIMCTX, width, height, channels, max_palette_size)
      i_img *img = i_img_pal_new(width, height, channels, max_palette_size)

    Creates a new paletted image of the supplied dimensions.

    "maxpal" is the maximum palette size and should normally be 256.

    Returns a new image or NULL on failure.

    Also callable as "i_img_pal_new(width, height, channels, max_palette_size)".

i_img_destroy("img")
      i_img_destroy(img)

    Destroy an image object

  Image Implementation

im_img_alloc(aIMCTX)
      i_img *im = im_img_alloc(aIMCTX);
      i_img *im = i_img_alloc();

    Allocates a new i_img structure.

    When implementing a new image type perform the following steps in your image object creation function:

    1.  allocate the image with i_img_alloc().

    2.  initialize any function pointers or other data as needed, you can overwrite the whole block if you need to.

    3.  initialize Imager's internal data by calling i_img_init() on the image object.

im_img_init(aIMCTX, image)
      im_img_init(aIMCTX, im);
      i_img_init(im);

    Imager internal initialization of images.

    See "im_img_alloc(aIMCTX)" for more information.

  Image Information

i_img_color_channels("im")
    The number of channels holding color information.

i_img_get_height("im")
      i_img_dim height = i_img_get_height(im);

    Returns the height in pixels of the image.

i_img_get_width("im")
      i_img_dim width = i_img_get_width(im);

    Returns the width in pixels of the image.

i_img_getchannels("im")
      int channels = i_img_getchannels(img);

    Get the number of channels in "im".

i_img_getmask("im")
      int mask = i_img_getmask(img);

    Get the image channel mask for "im".

i_img_has_alpha("im")
    Return true if the image has an alpha channel.

i_img_is_monochrome(img, &zero_is_white)
    Tests an image to check it meets our monochrome tests.

    The idea is that a file writer can use this to test where it should write the image in whatever bi-level format it uses, eg. "pbm" for "pnm".

    For performance of encoders we require monochrome images:

    •   be paletted

    •   have a palette of two colors, containing only "(0,0,0)" and "(255,255,255)" in either order.

    "zero_is_white" is set to non-zero if the first palette entry is white.

i_img_setmask("im", "ch_mask")
      // only channel 0 writable
      i_img_setmask(img, 0x01);

    Set the image channel mask for "im" to "ch_mask".

    The image channel mask gives some control over which channels can be written to in the image.

  Image quantization

i_quant_makemap("quant", "imgs", "count")
    Analyzes the "count" images in "imgs" according to the rules in "quant" to build a color map (optimal or not depending on "quant->make_colors").

i_quant_translate("quant", "img")
    Quantize the image given the palette in "quant".

    On success returns a pointer to a memory block of "img->xsize * img->ysize" "i_palidx" entries.

    On failure returns NULL.

    You should call myfree() on the returned block when you're done with it.

    This function will fail if the supplied palette contains no colors.

i_quant_transparent("quant", "data", "img", "trans_index")
    Dither the alpha channel on "img" into the palette indexes in "data". Pixels to be transparent are replaced with "trans_pixel".

    The method used depends on the tr_* members of "quant".

  Logging

i_lhead(file, line)
    This is an internal function called by the mm_log() macro.

i_loog(level, format, ...)
    This is an internal function called by the mm_log() macro.

  Mutex functions

i_mutex_new()
      i_mutex_t m = i_mutex_new();

    Create a mutex.

    If a critical section cannot be created for whatever reason, Imager will abort.

i_mutex_destroy(m)
      i_mutex_destroy(m);

    Destroy a mutex.

i_mutex_lock(m)
      i_mutex_lock(m);

    Lock the mutex, waiting if another thread has the mutex locked.

i_mutex_unlock(m)
      i_mutex_unlock(m);

    Release the mutex.

    The behavior of releasing a mutex you don't hold is unspecified.

  Paletted images

i_addcolors(im, colors, count)
    Adds colors to the image's palette.

    On success returns the index of the lowest color added.

    On failure returns -1.

    Always fails for direct color images.

i_colorcount(im)
    Returns the number of colors in the image's palette.

    Returns -1 for direct images.

i_findcolor(im, color, &entry)
    Searches the images palette for the given color.

    On success sets *entry to the index of the color, and returns true.

    On failure returns false.

    Always fails on direct color images.

i_getcolors(im, index, colors, count)
    Retrieves count colors starting from index in the image's palette.

    On success stores the colors into colors and returns true.

    On failure returns false.

    Always fails for direct color images.

    Fails if there are less than index+count colors in the image's palette.

i_maxcolors(im)
    Returns the maximum number of colors the palette can hold for the image.

    Returns -1 for direct color images.

i_setcolors(im, index, colors, count)
    Sets count colors starting from index in the image's palette.

    On success returns true.

    On failure returns false.

    The image must have at least index+count colors in it's palette for this to succeed.

    Always fails on direct color images.

  Tags

i_tags_delbycode(tags, code)
    Delete any tags with the given code.

    Returns the number of tags deleted.

i_tags_delbyname(tags, name)
    Delete any tags with the given name.

    Returns the number of tags deleted.

i_tags_delete(tags, index)
    Delete a tag by index.

    Returns true on success.

i_tags_destroy(tags)
    Destroys the given tags structure. Called by i_img_destroy().

i_tags_find(tags, name, start, &entry)
    Searches for a tag of the given name starting from index start.

    On success returns true and sets *entry.

    On failure returns false.

i_tags_findn(tags, code, start, &entry)
    Searches for a tag of the given code starting from index start.

    On success returns true and sets *entry.

    On failure returns false.

i_tags_get_color(tags, name, code, &value)
    Retrieve a tag specified by name or code as color.

    On success sets the i_color *value to the color and returns true.

    On failure returns false.

i_tags_get_float(tags, name, code, value)
    Retrieves a tag as a floating point value.

    If the tag has a string value then that is parsed as a floating point number, otherwise the integer value of the tag is used.

    On success sets *value and returns true.

    On failure returns false.

i_tags_get_int(tags, name, code, &value)
    Retrieve a tag specified by name or code as an integer.

    On success sets the int *value to the integer and returns true.

    On failure returns false.

i_tags_get_string(tags, name, code, value, value_size)
    Retrieves a tag by name or code as a string.

    On success copies the string to value for a max of value_size and returns true.

    On failure returns false.

    value_size must be at least large enough for a string representation of an integer.

    The copied value is always "NUL" terminated.

i_tags_new(i_img_tags *tags)
    Initialize a tags structure. Should not be used if the tags structure has been previously used.

    This should be called tags member of an i_img object on creation (in i_img_*_new() functions).

    To destroy the contents use i_tags_destroy()

i_tags_set(tags, name, data, size)
      i_tags_set(&img->tags, "i_comment", -1);

    Sets the given tag to the string data

    If size is -1 then the strlen(data) bytes are stored.

    Even on failure, if an existing tag name exists, it will be removed.

i_tags_set_color(tags, name, code, &value)
    Stores the given color as a tag with the given name and code.

i_tags_set_float(tags, name, code, value)
    Equivalent to i_tags_set_float2(tags, name, code, value, 30).

i_tags_set_float2(tags, name, code, value, places)
    Sets the tag with the given name and code to the given floating point value.

    Since tags are strings or ints, we convert the value to a string before storage at the precision specified by "places".

i_tags_setn("tags", "name", "idata")
      i_tags_setn(&img->tags, "i_xres", 204);
      i_tags_setn(&img->tags, "i_yres", 196);

    Sets the given tag to the integer "idata"

    Even on failure, if an existing tag "name" exists, it will be removed.

  Uncategorized functions

i_utf8_advance(char **p, size_t *len)
    Retrieve a "UTF-8" character from the stream.

    Modifies *p and *len to indicate the consumed characters.

    This doesn't support the extended "UTF-8" encoding used by later versions of Perl. Since this is typically used to implement text output by font drivers, the strings supplied shouldn't have such out of range characters.

    This doesn't check that the "UTF-8" character is using the shortest possible representation.

    Returns ~0UL on failure.

im_context_refdec(ctx, where) =section Context objects
      im_context_refdec(aIMCTX, "a description");

    Remove a reference to the context, releasing it if all references have been removed.

im_context_refinc(ctx, where) =section Context objects
      im_context_refinc(aIMCTX, "a description");

    Add a new reference to the context.

im_context_slot_get(ctx, slot)
    Retrieve the value previously stored in the given slot of the context object.

im_context_slot_new(destructor)
    Allocate a new context-local-storage slot.

    "desctructor" will be called when the context is destroyed if the corresponding slot is non-NULL.

im_context_slot_set(slot, value)
    Set the value of a slot.

    Returns true on success.

    Aborts if the slot supplied is invalid.

    If reallocation of slot storage fails, returns false.

im_errors(ctx)
      i_errmsg *errors = im_errors(aIMCTX);
      i_errmsg *errors = i_errors();

    Returns a pointer to the first element of an array of error messages, terminated by a NULL pointer. The highest level message is first.

    Also callable as "i_errors()".

im_get_context()
    Retrieve the context object for the current thread.

    Inside Imager itself this is just a function pointer, which the Imager.xs BOOT handler initializes for use within perl. If you're taking the Imager code and embedding it elsewhere you need to initialize the "im_get_context" pointer at some point.

UNDOCUMENTED
The following API functions are undocumented so far, hopefully this will change:

•   im_lhead

•   im_loog

•   mm_log

AUTHOR
Tony Cook <tonyc@cpan.org>

SEE ALSO
Imager, Imager::API, Imager::ExtUtils, Imager::Inline