NAME

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

SYNOPSIS

i_color color;
color.rgba.r = 255; color.rgba.g = 0; color.rgba.b = 255;
double x[] = { ... };
double y[] = { ... };
i_polygon_t poly;
poly.count = sizeof(x) / sizeof(*x);
poly.x = x;
poly.y = y;


# 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;
i_img_dim_u limit;
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);
i_poly_poly_aa(im, 1, &poly, mode, color);
i_poly_aa_m(im, count, x, y, mode, color);
i_poly_poly_aa_cfill(im, 1, &poly, mode, fill);
i_poly_aa_cfill(im, count, x, y, mode, fill);

# 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);
i_color_model_t cm = i_img_color_model(im);
int alpha_channel;
int has_alpha = i_img_alpha_channel(im, &alpha_channel);
int color_channels = i_img_color_channels(im);

# Image quantization

# Logging

# mutex
i_mutex_t mutex;

# 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_poly_fill_mode_t

Control how polygons are filled. Has the following values:

i_pfm_evenodd - simple even-odd fills.
i_pfm_nonzero - non-zero winding rule fills.

i_polygon_t

Represents a polygon. Has the following members:

x, y - arrays of x and y locations of vertices.
count - the number of entries in the x and y arrays.

im_context_t

Imager's per-thread context.

im_slot_t

Represents a slot in the context object.

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_img_dim_u

i_img_dim_u limit;

An unsigned variant of "i_img_dim".

i_color_model_t

Returned by "i_img_color_model(im)" to indicate the color model of the image.

An enumerated type with the following possible values:

icm_unknown - the image has no usable color data. In future versions of Imager this will be returned in a few limited cases, eg. when the source image is CMYK and the user has requested no color translation is done.
icm_gray - gray scale with no alpha channel.
icm_gray_alpha - gray scale with an alpha channel.
icm_rgb - RGB
icm_rgb_alpha - RGB with an alpha channel.

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_poly_aa_cfill_m(im, count, x, y, mode, fill)

i_poly_aa_cfill(im, count, x, y, mode, fill);

Fill a polygon defined by the points specified by the x and y arrays with the fill specified by fill.

i_poly_aa_m(im, count, x, y, mode, color)

i_poly_aa_m(im, count, x, y, mode, color);

Fill a polygon defined by the points specified by the x and y arrays with the color specified by color.

i_poly_poly_aa(im, count, polys, mode, color)

i_poly_poly_aa(im, 1, &poly, mode, color);

Fill the count polygons defined by polys the color specified by color.

At least one polygon must be supplied.

All polygons must have at least 3 points.

i_poly_poly_aa_cfill(im, count, polys, mode, fill)

i_poly_poly_aa_cfill(im, 1, &poly, mode, fill);

Fill the count polygons defined by polys the fill specified by fill.

At least one polygon must be supplied.

All polygons must have at least 3 points.

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.

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:

allocate the image with i_img_alloc().
initialize any function pointers or other data as needed, you can overwrite the whole block if you need to.
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_alpha_channel(im, &channel)

int alpha_channel;
int has_alpha = i_img_alpha_channel(im, &alpha_channel);

Work out the alpha channel for an image.

If the image has an alpha channel, sets *channel to the alpha channel index and returns non-zero.

If the image has no alpha channel, returns zero and *channel is not modified.

channel may be NULL.

i_img_color_channels(im)

int color_channels = i_img_color_channels(im);

Returns the number of color channels in the image. For now this is always 1 (for grayscale) or 3 (for RGB) but may be 0 in some special cases in a future release of Imager.

i_img_color_model(im)

i_color_model_t cm = i_img_color_model(im);

Returns the color model for the image.

A future version of Imager will allow for images with extra channels beyond gray/rgb and alpha.

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

i_mutex_t

i_mutex_t mutex;

Opaque type for Imager's mutex API.

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.

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>

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NAME

SYNOPSIS

DESCRIPTION

Blit tools

Data Types

Drawing

Error handling

Files

Fills

I/O Layers

Image

Image creation/destruction

Image Implementation

Image Information

Image quantization

Logging

mutex

Mutex functions

Paletted images

Tags

Uncategorized functions

UNDOCUMENTED

AUTHOR

SEE ALSO

Module Install Instructions