diff options
author | Peter Breitenlohner <peb@mppmu.mpg.de> | 2014-10-15 07:49:29 +0000 |
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committer | Peter Breitenlohner <peb@mppmu.mpg.de> | 2014-10-15 07:49:29 +0000 |
commit | f30e59e50f4dc8d3b3d043346af5b1beaff3e313 (patch) | |
tree | 370069828aa09ea4fa28477458e05e8fc649e1d7 /Build/source/libs/cairo/cairo-1.14.0/src/cairo-png.c | |
parent | f8c3097b508413f6171ad5332227256e32daddd1 (diff) |
cairo 1.14.0
git-svn-id: svn://tug.org/texlive/trunk@35377 c570f23f-e606-0410-a88d-b1316a301751
Diffstat (limited to 'Build/source/libs/cairo/cairo-1.14.0/src/cairo-png.c')
-rw-r--r-- | Build/source/libs/cairo/cairo-1.14.0/src/cairo-png.c | 819 |
1 files changed, 819 insertions, 0 deletions
diff --git a/Build/source/libs/cairo/cairo-1.14.0/src/cairo-png.c b/Build/source/libs/cairo/cairo-1.14.0/src/cairo-png.c new file mode 100644 index 00000000000..068617d588d --- /dev/null +++ b/Build/source/libs/cairo/cairo-1.14.0/src/cairo-png.c @@ -0,0 +1,819 @@ +/* cairo - a vector graphics library with display and print output + * + * Copyright © 2003 University of Southern California + * + * This library is free software; you can redistribute it and/or + * modify it either under the terms of the GNU Lesser General Public + * License version 2.1 as published by the Free Software Foundation + * (the "LGPL") or, at your option, under the terms of the Mozilla + * Public License Version 1.1 (the "MPL"). If you do not alter this + * notice, a recipient may use your version of this file under either + * the MPL or the LGPL. + * + * You should have received a copy of the LGPL along with this library + * in the file COPYING-LGPL-2.1; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA 02110-1335, USA + * You should have received a copy of the MPL along with this library + * in the file COPYING-MPL-1.1 + * + * The contents of this file are subject to the Mozilla Public License + * Version 1.1 (the "License"); you may not use this file except in + * compliance with the License. You may obtain a copy of the License at + * http://www.mozilla.org/MPL/ + * + * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY + * OF ANY KIND, either express or implied. See the LGPL or the MPL for + * the specific language governing rights and limitations. + * + * The Original Code is the cairo graphics library. + * + * The Initial Developer of the Original Code is University of Southern + * California. + * + * Contributor(s): + * Carl D. Worth <cworth@cworth.org> + * Kristian Høgsberg <krh@redhat.com> + * Chris Wilson <chris@chris-wilson.co.uk> + */ + +#include "cairoint.h" + +#include "cairo-error-private.h" +#include "cairo-image-surface-private.h" +#include "cairo-output-stream-private.h" + +#include <stdio.h> +#include <errno.h> +#include <png.h> + +/** + * SECTION:cairo-png + * @Title: PNG Support + * @Short_Description: Reading and writing PNG images + * @See_Also: #cairo_surface_t + * + * The PNG functions allow reading PNG images into image surfaces, and writing + * any surface to a PNG file. + * + * It is a toy API. It only offers very simple support for reading and + * writing PNG files, which is sufficient for testing and + * demonstration purposes. Applications which need more control over + * the generated PNG file should access the pixel data directly, using + * cairo_image_surface_get_data() or a backend-specific access + * function, and process it with another library, e.g. gdk-pixbuf or + * libpng. + **/ + +/** + * CAIRO_HAS_PNG_FUNCTIONS: + * + * Defined if the PNG functions are available. + * This macro can be used to conditionally compile code using the cairo + * PNG functions. + * + * Since: 1.0 + **/ + +struct png_read_closure_t { + cairo_read_func_t read_func; + void *closure; + cairo_output_stream_t *png_data; +}; + + +/* Unpremultiplies data and converts native endian ARGB => RGBA bytes */ +static void +unpremultiply_data (png_structp png, png_row_infop row_info, png_bytep data) +{ + unsigned int i; + + for (i = 0; i < row_info->rowbytes; i += 4) { + uint8_t *b = &data[i]; + uint32_t pixel; + uint8_t alpha; + + memcpy (&pixel, b, sizeof (uint32_t)); + alpha = (pixel & 0xff000000) >> 24; + if (alpha == 0) { + b[0] = b[1] = b[2] = b[3] = 0; + } else { + b[0] = (((pixel & 0xff0000) >> 16) * 255 + alpha / 2) / alpha; + b[1] = (((pixel & 0x00ff00) >> 8) * 255 + alpha / 2) / alpha; + b[2] = (((pixel & 0x0000ff) >> 0) * 255 + alpha / 2) / alpha; + b[3] = alpha; + } + } +} + +/* Converts native endian xRGB => RGBx bytes */ +static void +convert_data_to_bytes (png_structp png, png_row_infop row_info, png_bytep data) +{ + unsigned int i; + + for (i = 0; i < row_info->rowbytes; i += 4) { + uint8_t *b = &data[i]; + uint32_t pixel; + + memcpy (&pixel, b, sizeof (uint32_t)); + + b[0] = (pixel & 0xff0000) >> 16; + b[1] = (pixel & 0x00ff00) >> 8; + b[2] = (pixel & 0x0000ff) >> 0; + b[3] = 0; + } +} + +/* Use a couple of simple error callbacks that do not print anything to + * stderr and rely on the user to check for errors via the #cairo_status_t + * return. + */ +static void +png_simple_error_callback (png_structp png, + png_const_charp error_msg) +{ + cairo_status_t *error = png_get_error_ptr (png); + + /* default to the most likely error */ + if (*error == CAIRO_STATUS_SUCCESS) + *error = _cairo_error (CAIRO_STATUS_NO_MEMORY); + +#ifdef PNG_SETJMP_SUPPORTED + longjmp (png_jmpbuf (png), 1); +#endif + + /* if we get here, then we have to choice but to abort ... */ +} + +static void +png_simple_warning_callback (png_structp png, + png_const_charp error_msg) +{ + /* png does not expect to abort and will try to tidy up and continue + * loading the image after a warning. So we also want to return the + * (incorrect?) surface. + * + * We use our own warning callback to squelch any attempts by libpng + * to write to stderr as we may not be in control of that output. + */ +} + + +/* Starting with libpng-1.2.30, we must explicitly specify an output_flush_fn. + * Otherwise, we will segfault if we are writing to a stream. */ +static void +png_simple_output_flush_fn (png_structp png_ptr) +{ +} + +static cairo_status_t +write_png (cairo_surface_t *surface, + png_rw_ptr write_func, + void *closure) +{ + int i; + cairo_int_status_t status; + cairo_image_surface_t *image; + cairo_image_surface_t * volatile clone; + void *image_extra; + png_struct *png; + png_info *info; + png_byte **volatile rows = NULL; + png_color_16 white; + int png_color_type; + int bpc; + + status = _cairo_surface_acquire_source_image (surface, + &image, + &image_extra); + + if (status == CAIRO_INT_STATUS_UNSUPPORTED) + return _cairo_error (CAIRO_STATUS_SURFACE_TYPE_MISMATCH); + else if (unlikely (status)) + return status; + + /* PNG complains about "Image width or height is zero in IHDR" */ + if (image->width == 0 || image->height == 0) { + status = _cairo_error (CAIRO_STATUS_WRITE_ERROR); + goto BAIL1; + } + + /* Handle the various fallback formats (e.g. low bit-depth XServers) + * by coercing them to a simpler format using pixman. + */ + clone = _cairo_image_surface_coerce (image); + status = clone->base.status; + if (unlikely (status)) + goto BAIL1; + + rows = _cairo_malloc_ab (clone->height, sizeof (png_byte*)); + if (unlikely (rows == NULL)) { + status = _cairo_error (CAIRO_STATUS_NO_MEMORY); + goto BAIL2; + } + + for (i = 0; i < clone->height; i++) + rows[i] = (png_byte *) clone->data + i * clone->stride; + + png = png_create_write_struct (PNG_LIBPNG_VER_STRING, &status, + png_simple_error_callback, + png_simple_warning_callback); + if (unlikely (png == NULL)) { + status = _cairo_error (CAIRO_STATUS_NO_MEMORY); + goto BAIL3; + } + + info = png_create_info_struct (png); + if (unlikely (info == NULL)) { + status = _cairo_error (CAIRO_STATUS_NO_MEMORY); + goto BAIL4; + } + +#ifdef PNG_SETJMP_SUPPORTED + if (setjmp (png_jmpbuf (png))) + goto BAIL4; +#endif + + png_set_write_fn (png, closure, write_func, png_simple_output_flush_fn); + + switch (clone->format) { + case CAIRO_FORMAT_ARGB32: + bpc = 8; + if (_cairo_image_analyze_transparency (clone) == CAIRO_IMAGE_IS_OPAQUE) + png_color_type = PNG_COLOR_TYPE_RGB; + else + png_color_type = PNG_COLOR_TYPE_RGB_ALPHA; + break; + case CAIRO_FORMAT_RGB30: + bpc = 10; + png_color_type = PNG_COLOR_TYPE_RGB; + break; + case CAIRO_FORMAT_RGB24: + bpc = 8; + png_color_type = PNG_COLOR_TYPE_RGB; + break; + case CAIRO_FORMAT_A8: + bpc = 8; + png_color_type = PNG_COLOR_TYPE_GRAY; + break; + case CAIRO_FORMAT_A1: + bpc = 1; + png_color_type = PNG_COLOR_TYPE_GRAY; +#ifndef WORDS_BIGENDIAN + png_set_packswap (png); +#endif + break; + case CAIRO_FORMAT_INVALID: + case CAIRO_FORMAT_RGB16_565: + default: + status = _cairo_error (CAIRO_STATUS_INVALID_FORMAT); + goto BAIL4; + } + + png_set_IHDR (png, info, + clone->width, + clone->height, bpc, + png_color_type, + PNG_INTERLACE_NONE, + PNG_COMPRESSION_TYPE_DEFAULT, + PNG_FILTER_TYPE_DEFAULT); + + white.gray = (1 << bpc) - 1; + white.red = white.blue = white.green = white.gray; + png_set_bKGD (png, info, &white); + + if (0) { /* XXX extract meta-data from surface (i.e. creation date) */ + png_time pt; + + png_convert_from_time_t (&pt, time (NULL)); + png_set_tIME (png, info, &pt); + } + + /* We have to call png_write_info() before setting up the write + * transformation, since it stores data internally in 'png' + * that is needed for the write transformation functions to work. + */ + png_write_info (png, info); + + if (png_color_type == PNG_COLOR_TYPE_RGB_ALPHA) { + png_set_write_user_transform_fn (png, unpremultiply_data); + } else if (png_color_type == PNG_COLOR_TYPE_RGB) { + png_set_write_user_transform_fn (png, convert_data_to_bytes); + png_set_filler (png, 0, PNG_FILLER_AFTER); + } + + png_write_image (png, rows); + png_write_end (png, info); + +BAIL4: + png_destroy_write_struct (&png, &info); +BAIL3: + free (rows); +BAIL2: + cairo_surface_destroy (&clone->base); +BAIL1: + _cairo_surface_release_source_image (surface, image, image_extra); + + return status; +} + +static void +stdio_write_func (png_structp png, png_bytep data, png_size_t size) +{ + FILE *fp; + + fp = png_get_io_ptr (png); + while (size) { + size_t ret = fwrite (data, 1, size, fp); + size -= ret; + data += ret; + if (size && ferror (fp)) { + cairo_status_t *error = png_get_error_ptr (png); + if (*error == CAIRO_STATUS_SUCCESS) + *error = _cairo_error (CAIRO_STATUS_WRITE_ERROR); + png_error (png, NULL); + } + } +} + +/** + * cairo_surface_write_to_png: + * @surface: a #cairo_surface_t with pixel contents + * @filename: the name of a file to write to + * + * Writes the contents of @surface to a new file @filename as a PNG + * image. + * + * Return value: %CAIRO_STATUS_SUCCESS if the PNG file was written + * successfully. Otherwise, %CAIRO_STATUS_NO_MEMORY if memory could not + * be allocated for the operation or + * %CAIRO_STATUS_SURFACE_TYPE_MISMATCH if the surface does not have + * pixel contents, or %CAIRO_STATUS_WRITE_ERROR if an I/O error occurs + * while attempting to write the file. + * + * Since: 1.0 + **/ +cairo_status_t +cairo_surface_write_to_png (cairo_surface_t *surface, + const char *filename) +{ + FILE *fp; + cairo_status_t status; + + if (surface->status) + return surface->status; + + if (surface->finished) + return _cairo_error (CAIRO_STATUS_SURFACE_FINISHED); + + fp = fopen (filename, "wb"); + if (fp == NULL) { + switch (errno) { + case ENOMEM: + return _cairo_error (CAIRO_STATUS_NO_MEMORY); + default: + return _cairo_error (CAIRO_STATUS_WRITE_ERROR); + } + } + + status = write_png (surface, stdio_write_func, fp); + + if (fclose (fp) && status == CAIRO_STATUS_SUCCESS) + status = _cairo_error (CAIRO_STATUS_WRITE_ERROR); + + return status; +} + +struct png_write_closure_t { + cairo_write_func_t write_func; + void *closure; +}; + +static void +stream_write_func (png_structp png, png_bytep data, png_size_t size) +{ + cairo_status_t status; + struct png_write_closure_t *png_closure; + + png_closure = png_get_io_ptr (png); + status = png_closure->write_func (png_closure->closure, data, size); + if (unlikely (status)) { + cairo_status_t *error = png_get_error_ptr (png); + if (*error == CAIRO_STATUS_SUCCESS) + *error = status; + png_error (png, NULL); + } +} + +/** + * cairo_surface_write_to_png_stream: + * @surface: a #cairo_surface_t with pixel contents + * @write_func: a #cairo_write_func_t + * @closure: closure data for the write function + * + * Writes the image surface to the write function. + * + * Return value: %CAIRO_STATUS_SUCCESS if the PNG file was written + * successfully. Otherwise, %CAIRO_STATUS_NO_MEMORY is returned if + * memory could not be allocated for the operation, + * %CAIRO_STATUS_SURFACE_TYPE_MISMATCH if the surface does not have + * pixel contents. + * + * Since: 1.0 + **/ +cairo_status_t +cairo_surface_write_to_png_stream (cairo_surface_t *surface, + cairo_write_func_t write_func, + void *closure) +{ + struct png_write_closure_t png_closure; + + if (surface->status) + return surface->status; + + if (surface->finished) + return _cairo_error (CAIRO_STATUS_SURFACE_FINISHED); + + png_closure.write_func = write_func; + png_closure.closure = closure; + + return write_png (surface, stream_write_func, &png_closure); +} +slim_hidden_def (cairo_surface_write_to_png_stream); + +static inline int +multiply_alpha (int alpha, int color) +{ + int temp = (alpha * color) + 0x80; + return ((temp + (temp >> 8)) >> 8); +} + +/* Premultiplies data and converts RGBA bytes => native endian */ +static void +premultiply_data (png_structp png, + png_row_infop row_info, + png_bytep data) +{ + unsigned int i; + + for (i = 0; i < row_info->rowbytes; i += 4) { + uint8_t *base = &data[i]; + uint8_t alpha = base[3]; + uint32_t p; + + if (alpha == 0) { + p = 0; + } else { + uint8_t red = base[0]; + uint8_t green = base[1]; + uint8_t blue = base[2]; + + if (alpha != 0xff) { + red = multiply_alpha (alpha, red); + green = multiply_alpha (alpha, green); + blue = multiply_alpha (alpha, blue); + } + p = (alpha << 24) | (red << 16) | (green << 8) | (blue << 0); + } + memcpy (base, &p, sizeof (uint32_t)); + } +} + +/* Converts RGBx bytes to native endian xRGB */ +static void +convert_bytes_to_data (png_structp png, png_row_infop row_info, png_bytep data) +{ + unsigned int i; + + for (i = 0; i < row_info->rowbytes; i += 4) { + uint8_t *base = &data[i]; + uint8_t red = base[0]; + uint8_t green = base[1]; + uint8_t blue = base[2]; + uint32_t pixel; + + pixel = (0xff << 24) | (red << 16) | (green << 8) | (blue << 0); + memcpy (base, &pixel, sizeof (uint32_t)); + } +} + +static cairo_status_t +stdio_read_func (void *closure, unsigned char *data, unsigned int size) +{ + FILE *file = closure; + + while (size) { + size_t ret; + + ret = fread (data, 1, size, file); + size -= ret; + data += ret; + + if (size && (feof (file) || ferror (file))) + return _cairo_error (CAIRO_STATUS_READ_ERROR); + } + + return CAIRO_STATUS_SUCCESS; +} + +static void +stream_read_func (png_structp png, png_bytep data, png_size_t size) +{ + cairo_status_t status; + struct png_read_closure_t *png_closure; + + png_closure = png_get_io_ptr (png); + status = png_closure->read_func (png_closure->closure, data, size); + if (unlikely (status)) { + cairo_status_t *error = png_get_error_ptr (png); + if (*error == CAIRO_STATUS_SUCCESS) + *error = status; + png_error (png, NULL); + } + + _cairo_output_stream_write (png_closure->png_data, data, size); +} + +static cairo_surface_t * +read_png (struct png_read_closure_t *png_closure) +{ + cairo_surface_t *surface; + png_struct *png = NULL; + png_info *info; + png_byte *data = NULL; + png_byte **row_pointers = NULL; + png_uint_32 png_width, png_height; + int depth, color_type, interlace, stride; + unsigned int i; + cairo_format_t format; + cairo_status_t status; + unsigned char *mime_data; + unsigned long mime_data_length; + + png_closure->png_data = _cairo_memory_stream_create (); + + /* XXX: Perhaps we'll want some other error handlers? */ + png = png_create_read_struct (PNG_LIBPNG_VER_STRING, + &status, + png_simple_error_callback, + png_simple_warning_callback); + if (unlikely (png == NULL)) { + surface = _cairo_surface_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY)); + goto BAIL; + } + + info = png_create_info_struct (png); + if (unlikely (info == NULL)) { + surface = _cairo_surface_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY)); + goto BAIL; + } + + png_set_read_fn (png, png_closure, stream_read_func); + + status = CAIRO_STATUS_SUCCESS; +#ifdef PNG_SETJMP_SUPPORTED + if (setjmp (png_jmpbuf (png))) { + surface = _cairo_surface_create_in_error (status); + goto BAIL; + } +#endif + + png_read_info (png, info); + + png_get_IHDR (png, info, + &png_width, &png_height, &depth, + &color_type, &interlace, NULL, NULL); + if (unlikely (status)) { /* catch any early warnings */ + surface = _cairo_surface_create_in_error (status); + goto BAIL; + } + + /* convert palette/gray image to rgb */ + if (color_type == PNG_COLOR_TYPE_PALETTE) + png_set_palette_to_rgb (png); + + /* expand gray bit depth if needed */ + if (color_type == PNG_COLOR_TYPE_GRAY) { +#if PNG_LIBPNG_VER >= 10209 + png_set_expand_gray_1_2_4_to_8 (png); +#else + png_set_gray_1_2_4_to_8 (png); +#endif + } + + /* transform transparency to alpha */ + if (png_get_valid (png, info, PNG_INFO_tRNS)) + png_set_tRNS_to_alpha (png); + + if (depth == 16) + png_set_strip_16 (png); + + if (depth < 8) + png_set_packing (png); + + /* convert grayscale to RGB */ + if (color_type == PNG_COLOR_TYPE_GRAY || + color_type == PNG_COLOR_TYPE_GRAY_ALPHA) + { + png_set_gray_to_rgb (png); + } + + if (interlace != PNG_INTERLACE_NONE) + png_set_interlace_handling (png); + + png_set_filler (png, 0xff, PNG_FILLER_AFTER); + + /* recheck header after setting EXPAND options */ + png_read_update_info (png, info); + png_get_IHDR (png, info, + &png_width, &png_height, &depth, + &color_type, &interlace, NULL, NULL); + if (depth != 8 || + ! (color_type == PNG_COLOR_TYPE_RGB || + color_type == PNG_COLOR_TYPE_RGB_ALPHA)) + { + surface = _cairo_surface_create_in_error (_cairo_error (CAIRO_STATUS_READ_ERROR)); + goto BAIL; + } + + switch (color_type) { + default: + ASSERT_NOT_REACHED; + /* fall-through just in case ;-) */ + + case PNG_COLOR_TYPE_RGB_ALPHA: + format = CAIRO_FORMAT_ARGB32; + png_set_read_user_transform_fn (png, premultiply_data); + break; + + case PNG_COLOR_TYPE_RGB: + format = CAIRO_FORMAT_RGB24; + png_set_read_user_transform_fn (png, convert_bytes_to_data); + break; + } + + stride = cairo_format_stride_for_width (format, png_width); + if (stride < 0) { + surface = _cairo_surface_create_in_error (_cairo_error (CAIRO_STATUS_INVALID_STRIDE)); + goto BAIL; + } + + data = _cairo_malloc_ab (png_height, stride); + if (unlikely (data == NULL)) { + surface = _cairo_surface_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY)); + goto BAIL; + } + + row_pointers = _cairo_malloc_ab (png_height, sizeof (char *)); + if (unlikely (row_pointers == NULL)) { + surface = _cairo_surface_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY)); + goto BAIL; + } + + for (i = 0; i < png_height; i++) + row_pointers[i] = &data[i * stride]; + + png_read_image (png, row_pointers); + png_read_end (png, info); + + if (unlikely (status)) { /* catch any late warnings - probably hit an error already */ + surface = _cairo_surface_create_in_error (status); + goto BAIL; + } + + surface = cairo_image_surface_create_for_data (data, format, + png_width, png_height, + stride); + if (surface->status) + goto BAIL; + + _cairo_image_surface_assume_ownership_of_data ((cairo_image_surface_t*)surface); + data = NULL; + + _cairo_debug_check_image_surface_is_defined (surface); + + status = _cairo_memory_stream_destroy (png_closure->png_data, + &mime_data, + &mime_data_length); + png_closure->png_data = NULL; + if (unlikely (status)) { + cairo_surface_destroy (surface); + surface = _cairo_surface_create_in_error (status); + goto BAIL; + } + + status = cairo_surface_set_mime_data (surface, + CAIRO_MIME_TYPE_PNG, + mime_data, + mime_data_length, + free, + mime_data); + if (unlikely (status)) { + free (mime_data); + cairo_surface_destroy (surface); + surface = _cairo_surface_create_in_error (status); + goto BAIL; + } + + BAIL: + free (row_pointers); + free (data); + if (png != NULL) + png_destroy_read_struct (&png, &info, NULL); + if (png_closure->png_data != NULL) { + cairo_status_t status_ignored; + + status_ignored = _cairo_output_stream_destroy (png_closure->png_data); + } + + return surface; +} + +/** + * cairo_image_surface_create_from_png: + * @filename: name of PNG file to load + * + * Creates a new image surface and initializes the contents to the + * given PNG file. + * + * Return value: a new #cairo_surface_t initialized with the contents + * of the PNG file, or a "nil" surface if any error occurred. A nil + * surface can be checked for with cairo_surface_status(surface) which + * may return one of the following values: + * + * %CAIRO_STATUS_NO_MEMORY + * %CAIRO_STATUS_FILE_NOT_FOUND + * %CAIRO_STATUS_READ_ERROR + * + * Alternatively, you can allow errors to propagate through the drawing + * operations and check the status on the context upon completion + * using cairo_status(). + * + * Since: 1.0 + **/ +cairo_surface_t * +cairo_image_surface_create_from_png (const char *filename) +{ + struct png_read_closure_t png_closure; + cairo_surface_t *surface; + + png_closure.closure = fopen (filename, "rb"); + if (png_closure.closure == NULL) { + cairo_status_t status; + switch (errno) { + case ENOMEM: + status = _cairo_error (CAIRO_STATUS_NO_MEMORY); + break; + case ENOENT: + status = _cairo_error (CAIRO_STATUS_FILE_NOT_FOUND); + break; + default: + status = _cairo_error (CAIRO_STATUS_READ_ERROR); + break; + } + return _cairo_surface_create_in_error (status); + } + + png_closure.read_func = stdio_read_func; + + surface = read_png (&png_closure); + + fclose (png_closure.closure); + + return surface; +} + +/** + * cairo_image_surface_create_from_png_stream: + * @read_func: function called to read the data of the file + * @closure: data to pass to @read_func. + * + * Creates a new image surface from PNG data read incrementally + * via the @read_func function. + * + * Return value: a new #cairo_surface_t initialized with the contents + * of the PNG file or a "nil" surface if the data read is not a valid PNG image + * or memory could not be allocated for the operation. A nil + * surface can be checked for with cairo_surface_status(surface) which + * may return one of the following values: + * + * %CAIRO_STATUS_NO_MEMORY + * %CAIRO_STATUS_READ_ERROR + * + * Alternatively, you can allow errors to propagate through the drawing + * operations and check the status on the context upon completion + * using cairo_status(). + * + * Since: 1.0 + **/ +cairo_surface_t * +cairo_image_surface_create_from_png_stream (cairo_read_func_t read_func, + void *closure) +{ + struct png_read_closure_t png_closure; + + png_closure.read_func = read_func; + png_closure.closure = closure; + + return read_png (&png_closure); +} |