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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;
 
 
   # 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;
 
   # 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
   i_clear_error();
   i_push_error(0, "Yep, it's broken");
   i_push_error(errno, "Error writing");
   i_push_errorf(errno, "Cannot open file %s: %d", filename, errno);
 
   # Files
   i_set_image_file_limits(500, 500, 1000000);
   i_get_image_file_limits(&width, &height, &bytes)
   i_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);
 
   # Image
 
   # Image creation/destruction
   i_img *img = i_img_8_new(width, height, channels);
   i_img *img = i_sametype(src, width, height);
   i_img *img = i_sametype_chans(src, width, height, channels);
   i_img *img = i_img_pal_new(width, height, channels, max_palette_size)
   i_img *img = i_img_double_new(width, height, channels);
   i_img *img = i_img_16_new(width, height, channels);
   i_img_destroy(img)
 
   # Image Implementation
 
   # Image Information
   // only channel 0 writeable 
   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
 
   # 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

Data Types

i_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_color

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

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

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

May be larger than int on some platforms.

Drawing

i_arc(im, x, y, rad, d1, d2, 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)

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)

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)

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)

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

i_box_cfill(im, x1, y1, x2, y2, fill)

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

i_box_filled(im, x1, y1, x2, y2, color)

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

i_circle_aa(im, x, y, rad, color)

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

i_flood_cfill("im", "seedx", "seedy", "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")

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")

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")

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_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_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.

Error handling

i_clear_error()

Clears the error stack.

Called by any Imager function before doing any other processing.

i_push_error(int code, char const *msg)

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.).

i_push_errorf(int code, char const *fmt, ...)

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

Does not support perl specific format codes.

i_push_errorvf(int "code", char const *"fmt", va_list "ap")

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.

Files

i_get_image_file_limits(&width, &height, &bytes)

Retrieves the file limits set by i_set_image_file_limits().

i_int_check_image_file_limits(width, height, channels, sample_size)

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.

i_set_image_file_limits(width, height, bytes)

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.

Returns non-zero on success.

Fills

i_new_fill_fount("xa", "ya", "xb", "yb", "type", "repeat", "combine", "super_sample", "ssample_param", "count", "segs")

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

i_new_fill_hatch("fg", "bg", "combine", "hatch", "cust_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 the side of a filled area.

i_new_fill_hatchf("fg", "bg", "combine", "hatch", "cust_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 the side of a filled area.

i_new_fill_image("im", "matrix", "xoff", "yoff", "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)

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)

Create a solid fill based on a float color.

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

i_fill_destroy(fill)

Call to destroy any fill object.

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_img_16_new(x, y, ch)

Create a new 16-bit/sample image.

Returns the image on success, or NULL on failure.

i_img_8_new(x, y, ch)

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

i_img_double_new(int x, int y, int ch)

Creates a new double per sample image.

i_img_pal_new("x", "y", "channels", "maxpal")

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.

i_sametype("im", "xsize", "ysize")

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")

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

For paletted images the equivalent direct type is returned.

i_img_destroy("img")

Destroy an image object

Image Implementation

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.

i_img_init("img")

Imager internal initialization of images.

Currently this does very little, in the future it may be used to support threads, or color profiles.

Image Information

i_img_color_channels("im")

The number of channels holding color information.

i_img_get_height("im")

Returns the height in pixels of the image.

i_img_get_width("im")

Returns the width in pixels of the image.

i_img_getchannels("im")

Get the number of channels in "im".

i_img_getmask("im")

Get the image channel mask for "im".

i_img_has_alpha("im")

Return true if the image has an alpha channel.

i_img_setmask("im", "ch_mask")

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.

mm_log((level, format, ...))

This is the main entry point to logging. Note that the extra set of parentheses are required due to limitations in C89 macros.

This will format a string with the current file and line number to the log file if logging is enabled.

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)

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")

Sets the given tag to the integer "idata"

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

AUTHOR

Tony Cook <tony@imager.perl.org>

SEE ALSO

Imager, Imager::ExtUtils, Imager::Inline