int main(int argc,char *argv[]) { FILE *fin,*fout; png_structp read_ptr,write_ptr; fin = fopen("pngtest.png","rb"); fout = fopen("out.png","wb"); png_infop read_info_ptr,write_info_ptr; read_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, png_voidp_NULL,png_error_ptr_NULL, png_error_ptr_NULL); read_info_ptr = png_create_info_struct(read_ptr); write_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, png_voidp_NULL, png_error_ptr_NULL, png_error_ptr_NULL); write_info_ptr = png_create_info_struct(write_ptr); png_init_io(read_ptr, fin); png_init_io(write_ptr, fout); png_read_info(read_ptr,read_info_ptr); png_write_info_before_PLTE(write_ptr, write_info_ptr); return 0; }
void PNGAPI png_write_info(png_structp png_ptr, png_infop info_ptr) { #if defined(PNG_WRITE_TEXT_SUPPORTED) || defined(PNG_WRITE_sPLT_SUPPORTED) int i; #endif png_debug(1, "in png_write_info"); if (png_ptr == NULL || info_ptr == NULL) return; png_write_info_before_PLTE(png_ptr, info_ptr); if (info_ptr->valid & PNG_INFO_PLTE) png_write_PLTE(png_ptr, info_ptr->palette, (png_uint_32)info_ptr->num_palette); else if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE) png_error(png_ptr, "Valid palette required for paletted images"); #ifdef PNG_WRITE_tRNS_SUPPORTED if (info_ptr->valid & PNG_INFO_tRNS) { #ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED /* Invert the alpha channel (in tRNS) */ if ((png_ptr->transformations & PNG_INVERT_ALPHA) && info_ptr->color_type == PNG_COLOR_TYPE_PALETTE) { int j; for (j = 0; j<(int)info_ptr->num_trans; j++) info_ptr->trans_alpha[j] = (png_byte)(255 - info_ptr->trans_alpha[j]); } #endif png_write_tRNS(png_ptr, info_ptr->trans_alpha, &(info_ptr->trans_color), info_ptr->num_trans, info_ptr->color_type); } #endif #ifdef PNG_WRITE_bKGD_SUPPORTED if (info_ptr->valid & PNG_INFO_bKGD) png_write_bKGD(png_ptr, &(info_ptr->background), info_ptr->color_type); #endif #ifdef PNG_WRITE_hIST_SUPPORTED if (info_ptr->valid & PNG_INFO_hIST) png_write_hIST(png_ptr, info_ptr->hist, info_ptr->num_palette); #endif #ifdef PNG_WRITE_oFFs_SUPPORTED if (info_ptr->valid & PNG_INFO_oFFs) png_write_oFFs(png_ptr, info_ptr->x_offset, info_ptr->y_offset, info_ptr->offset_unit_type); #endif #ifdef PNG_WRITE_pCAL_SUPPORTED if (info_ptr->valid & PNG_INFO_pCAL) png_write_pCAL(png_ptr, info_ptr->pcal_purpose, info_ptr->pcal_X0, info_ptr->pcal_X1, info_ptr->pcal_type, info_ptr->pcal_nparams, info_ptr->pcal_units, info_ptr->pcal_params); #endif #ifdef PNG_WRITE_sCAL_SUPPORTED if (info_ptr->valid & PNG_INFO_sCAL) png_write_sCAL_s(png_ptr, (int)info_ptr->scal_unit, info_ptr->scal_s_width, info_ptr->scal_s_height); #endif /* sCAL */ #ifdef PNG_WRITE_pHYs_SUPPORTED if (info_ptr->valid & PNG_INFO_pHYs) png_write_pHYs(png_ptr, info_ptr->x_pixels_per_unit, info_ptr->y_pixels_per_unit, info_ptr->phys_unit_type); #endif /* pHYs */ #ifdef PNG_WRITE_tIME_SUPPORTED if (info_ptr->valid & PNG_INFO_tIME) { png_write_tIME(png_ptr, &(info_ptr->mod_time)); png_ptr->mode |= PNG_WROTE_tIME; } #endif /* tIME */ #ifdef PNG_WRITE_sPLT_SUPPORTED if (info_ptr->valid & PNG_INFO_sPLT) for (i = 0; i < (int)info_ptr->splt_palettes_num; i++) png_write_sPLT(png_ptr, info_ptr->splt_palettes + i); #endif /* sPLT */ #ifdef PNG_WRITE_TEXT_SUPPORTED /* Check to see if we need to write text chunks */ for (i = 0; i < info_ptr->num_text; i++) { png_debug2(2, "Writing header text chunk %d, type %d", i, info_ptr->text[i].compression); /* An internationalized chunk? */ if (info_ptr->text[i].compression > 0) { #ifdef PNG_WRITE_iTXt_SUPPORTED /* Write international chunk */ png_write_iTXt(png_ptr, info_ptr->text[i].compression, info_ptr->text[i].key, info_ptr->text[i].lang, info_ptr->text[i].lang_key, info_ptr->text[i].text); /* Mark this chunk as written */ if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_NONE) info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR; else info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_zTXt_WR; #else png_warning(png_ptr, "Unable to write international text"); #endif } /* If we want a compressed text chunk */ else if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_zTXt) { #ifdef PNG_WRITE_zTXt_SUPPORTED /* Write compressed chunk */ png_write_zTXt(png_ptr, info_ptr->text[i].key, info_ptr->text[i].text, 0, info_ptr->text[i].compression); /* Mark this chunk as written */ info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_zTXt_WR; #else png_warning(png_ptr, "Unable to write compressed text"); #endif } else if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_NONE) { #ifdef PNG_WRITE_tEXt_SUPPORTED /* Write uncompressed chunk */ png_write_tEXt(png_ptr, info_ptr->text[i].key, info_ptr->text[i].text, 0); /* Mark this chunk as written */ info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR; #else /* Can't get here */ png_warning(png_ptr, "Unable to write uncompressed text"); #endif } } #endif /* tEXt */ #ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED if (info_ptr->unknown_chunks_num) { png_unknown_chunk *up; png_debug(5, "writing extra chunks"); for (up = info_ptr->unknown_chunks; up < info_ptr->unknown_chunks + info_ptr->unknown_chunks_num; up++) { int keep = png_handle_as_unknown(png_ptr, up->name); if (keep != PNG_HANDLE_CHUNK_NEVER && up->location && (up->location & PNG_HAVE_PLTE) && !(up->location & PNG_HAVE_IDAT) && !(up->location & PNG_AFTER_IDAT) && ((up->name[3] & 0x20) || keep == PNG_HANDLE_CHUNK_ALWAYS || (png_ptr->flags & PNG_FLAG_KEEP_UNSAFE_CHUNKS))) { png_write_chunk(png_ptr, up->name, up->data, up->size); } } } #endif }