45 ptr = (
void *)mem->stream_ptr;
46 offset = mem->stream_len;
47 memcpy(data, ptr + offset, length);
48 mem->stream_len += length;
69 ptr = mem->stream_ptr;
70 offset = mem->stream_len;
71 memcpy(ptr + offset, data, length);
72 mem->stream_len += length;
130 int interlace, color, compres, filter, bit_depth;
131 g2int j, k, n, bytes;
133 png_infop info_ptr, end_info;
134 png_bytepp row_pointers;
136 png_uint_32 h32, w32;
139 if (png_sig_cmp(pngbuf, 0, 8) != 0)
143 if (!(png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, (png_voidp)NULL,
147 if (!(info_ptr = png_create_info_struct(png_ptr)))
149 png_destroy_read_struct(&png_ptr, (png_infopp)NULL, (png_infopp)NULL);
153 if (!(end_info = png_create_info_struct(png_ptr)))
155 png_destroy_read_struct(&png_ptr, (png_infopp)info_ptr, (png_infopp)NULL);
160 if (setjmp(png_jmpbuf(png_ptr)))
162 png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
167 read_io_ptr.stream_ptr = (png_voidp)pngbuf;
168 read_io_ptr.stream_len = 0;
171 png_set_read_fn(png_ptr, (png_voidp)&read_io_ptr, (png_rw_ptr)
user_read_data);
177 png_read_png(png_ptr, info_ptr, PNG_TRANSFORM_IDENTITY, NULL);
180 row_pointers = png_get_rows(png_ptr, info_ptr);
185 (void)png_get_IHDR(png_ptr, info_ptr, &w32, &h32,
186 &bit_depth, &color, &interlace, &compres, &filter);
197 if (color == PNG_COLOR_TYPE_RGB)
199 else if (color == PNG_COLOR_TYPE_RGB_ALPHA)
204 bytes = (*width * bit_depth) / 8;
205 if ((*width * bit_depth) % 8 != 0)
209 for (j = 0; j < *height; j++)
211 for (k = 0; k < bytes; k++)
213 cout[n] = *(row_pointers[j] + k);
219 png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
260 unsigned char *pngbuf)
263 g2int j, bytes, pnglen, bit_depth;
266 png_bytep **row_pointers;
270 if (!(png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL)))
273 if (!(info_ptr = png_create_info_struct(png_ptr)))
275 png_destroy_write_struct(&png_ptr, (png_infopp)NULL);
280 if (setjmp(png_jmpbuf(png_ptr)))
282 png_destroy_write_struct(&png_ptr, &info_ptr);
287 write_io_ptr.stream_ptr = (png_voidp)pngbuf;
288 write_io_ptr.stream_len = 0;
291 png_set_write_fn(png_ptr, (png_voidp)&write_io_ptr, (png_rw_ptr)
user_write_data,
296 color_type = PNG_COLOR_TYPE_GRAY;
300 color_type = PNG_COLOR_TYPE_RGB;
302 else if (nbits == 32)
305 color_type = PNG_COLOR_TYPE_RGB_ALPHA;
307 png_set_IHDR(png_ptr, info_ptr, width, height,
308 bit_depth, color_type, PNG_INTERLACE_NONE,
309 PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
312 bytes = (width * nbits) / 8;
313 if ((width * nbits) % 8 != 0)
318 row_pointers = malloc(height *
sizeof(png_bytep));
319 for (j = 0; j < height; j++)
320 row_pointers[j] = (png_bytep *)(data + (j * bytes));
322 png_set_rows(png_ptr, info_ptr, (png_bytepp)row_pointers);
325 png_write_png(png_ptr, info_ptr, PNG_TRANSFORM_IDENTITY, NULL);
328 png_destroy_write_struct(&png_ptr, &info_ptr);
330 pnglen = write_io_ptr.stream_len;
void user_read_data(png_structp, png_bytep, png_uint_32)
Custom read function used so that libpng will read a PNG stream from memory instead of a file on disk...
void user_write_data(png_structp, png_bytep, png_uint_32)
Custom write function used to that libpng will write to memory location instead of a file on disk.