src/graphics/PreviewLoader.cpp

   1 /**
   2  * \file PreviewLoader.cpp
   3  * This file is part of LyX, the document processor.
   4  * Licence details can be found in the file COPYING.
   5  *
   6  * \author Angus Leeming
   7  *
   8  * Full author contact details are available in file CREDITS.
   9  */
  10
  11 #include <config.h>
  12
  13 #include "PreviewLoader.h"
  14 #include "PreviewImage.h"
  15 #include "GraphicsCache.h"
  16
  17 #include "Buffer.h"
  18 #include "BufferParams.h"
  19 #include "Converter.h"
  20 #include "Encoding.h"
  21 #include "Format.h"
  22 #include "InsetIterator.h"
  23 #include "LaTeXFeatures.h"
  24 #include "LyXRC.h"
  25 #include "output.h"
  26 #include "OutputParams.h"
  27 #include "TexRow.h"
  28
  29 #include "frontends/Application.h" // hexName
  30
  31 #include "insets/Inset.h"
  32
  33 #include "support/convert.h"
  34 #include "support/debug.h"
  35 #include "support/FileName.h"
  36 #include "support/filetools.h"
  37 #include "support/ForkedCalls.h"
  38 #include "support/lstrings.h"
  39
  40 #include "support/bind.h"
  41 #include "support/TempFile.h"
  42
  43 #include <sstream>
  44 #include <fstream>
  45 #include <iomanip>
  46
  47 using namespace std;
  48 using namespace lyx::support;
  49
  50
  51
  52 namespace {
  53
  54 typedef pair<string, FileName> SnippetPair;
  55
  56 // A list of all snippets to be converted to previews
  57 typedef list<string> PendingSnippets;
  58
  59 // Each item in the vector is a pair<snippet, image file name>.
  60 typedef vector<SnippetPair> BitmapFile;
  61
  62
  63 FileName const unique_tex_filename(FileName const & bufferpath)
  64 {
  65         TempFile tempfile(bufferpath, "lyxpreviewXXXXXX.tex");
  66         tempfile.setAutoRemove(false);
  67         return tempfile.name();
  68 }
  69
  70
  71 lyx::Converter const * setConverter(string const & from)
  72 {
  73         typedef vector<string> FmtList;
  74         typedef lyx::graphics::Cache GCache;
  75         FmtList const & loadableFormats = GCache::get().loadableFormats();
  76         FmtList::const_iterator it = loadableFormats.begin();
  77         FmtList::const_iterator const end = loadableFormats.end();
  78
  79         for (; it != end; ++it) {
  80                 string const to = *it;
  81                 if (from == to)
  82                         continue;
  83
  84                 lyx::Converter const * ptr = lyx::theConverters().getConverter(from, to);
  85                 if (ptr)
  86                         return ptr;
  87         }
  88
  89         // FIXME THREAD
  90         static bool first = true;
  91         if (first) {
  92                 first = false;
  93                 LYXERR0("PreviewLoader::startLoading()\n"
  94                         << "No converter from \"" << from << "\" format has been defined.");
  95         }
  96         return 0;
  97 }
  98
  99
 100 void setAscentFractions(vector<double> & ascent_fractions,
 101                         FileName const & metrics_file)
 102 {
 103         // If all else fails, then the images will have equal ascents and
 104         // descents.
 105         vector<double>::iterator it  = ascent_fractions.begin();
 106         vector<double>::iterator end = ascent_fractions.end();
 107         fill(it, end, 0.5);
 108
 109         ifstream in(metrics_file.toFilesystemEncoding().c_str());
 110         if (!in.good()) {
 111                 LYXERR(lyx::Debug::GRAPHICS, "setAscentFractions(" << metrics_file << ")\n"
 112                         << "Unable to open file!");
 113                 return;
 114         }
 115
 116         bool error = false;
 117
 118         int snippet_counter = 1;
 119         while (!in.eof() && it != end) {
 120                 string snippet;
 121                 int id;
 122                 double ascent_fraction;
 123
 124                 in >> snippet >> id >> ascent_fraction;
 125
 126                 if (!in.good())
 127                         // eof after all
 128                         break;
 129
 130                 error = snippet != "Snippet";
 131                 if (error)
 132                         break;
 133
 134                 error = id != snippet_counter;
 135                 if (error)
 136                         break;
 137
 138                 *it = ascent_fraction;
 139
 140                 ++snippet_counter;
 141                 ++it;
 142         }
 143
 144         if (error) {
 145                 LYXERR(lyx::Debug::GRAPHICS, "setAscentFractions(" << metrics_file << ")\n"
 146                         << "Error reading file!\n");
 147         }
 148 }
 149
 150
 151 class FindFirst
 152 {
 153 public:
 154         FindFirst(string const & comp) : comp_(comp) {}
 155         bool operator()(SnippetPair const & sp) const { return sp.first == comp_; }
 156 private:
 157         string const comp_;
 158 };
 159
 160
 161 /// Store info on a currently executing, forked process.
 162 class InProgress {
 163 public:
 164         ///
 165         InProgress() : pid(0) {}
 166         ///
 167         InProgress(string const & filename_base,
 168                    PendingSnippets const & pending,
 169                    string const & to_format);
 170         /// Remove any files left lying around and kill the forked process.
 171         void stop() const;
 172
 173         ///
 174         pid_t pid;
 175         ///
 176         string command;
 177         ///
 178         FileName metrics_file;
 179         ///
 180         BitmapFile snippets;
 181 };
 182
 183 typedef map<pid_t, InProgress>  InProgressProcesses;
 184
 185 typedef InProgressProcesses::value_type InProgressProcess;
 186
 187 } // namespace anon
 188
 189
 190
 191 namespace lyx {
 192 namespace graphics {
 193
 194 class PreviewLoader::Impl : public boost::signals::trackable {
 195 public:
 196         ///
 197         Impl(PreviewLoader & p, Buffer const & b);
 198         /// Stop any InProgress items still executing.
 199         ~Impl();
 200         ///
 201         PreviewImage const * preview(string const & latex_snippet) const;
 202         ///
 203         PreviewLoader::Status status(string const & latex_snippet) const;
 204         ///
 205         void add(string const & latex_snippet);
 206         ///
 207         void remove(string const & latex_snippet);
 208         /// Record math macro definitions added to the loader
 209         void addMacroDef(docstring const & latex_snippet);
 210         /// Has a math macro definition already been added to the loader?
 211         bool hasMacroDef(docstring const & latex_snippet) const;
 212         /// \p wait whether to wait for the process to complete or, instead,
 213         /// to do it in the background.
 214         void startLoading(bool wait = false);
 215
 216         /// Emit this signal when an image is ready for display.
 217         boost::signal<void(PreviewImage const &)> imageReady;
 218
 219         Buffer const & buffer() const { return buffer_; }
 220
 221 private:
 222         /// Called by the ForkedCall process that generated the bitmap files.
 223         void finishedGenerating(pid_t, int);
 224         ///
 225         void dumpPreamble(otexstream &, OutputParams::FLAVOR) const;
 226         ///
 227         void dumpData(odocstream &, BitmapFile const &) const;
 228
 229         /** cache_ allows easy retrieval of already-generated images
 230          *  using the LaTeX snippet as the identifier.
 231          */
 232         typedef shared_ptr<PreviewImage> PreviewImagePtr;
 233         ///
 234         typedef map<string, PreviewImagePtr> Cache;
 235         ///
 236         Cache cache_;
 237
 238         /** pending_ stores the LaTeX snippets in anticipation of them being
 239          *  sent to the converter.
 240          */
 241         PendingSnippets pending_;
 242
 243         /** in_progress_ stores all forked processes so that we can proceed
 244          *  thereafter.
 245             The map uses the conversion commands as its identifiers.
 246          */
 247         InProgressProcesses in_progress_;
 248
 249         ///
 250         set<docstring> macrodefs_;
 251
 252         ///
 253         PreviewLoader & parent_;
 254         ///
 255         Buffer const & buffer_;
 256         ///
 257         mutable int font_scaling_factor_;
 258
 259         /// We don't own this
 260         static lyx::Converter const * pconverter_;
 261 };
 262
 263
 264 lyx::Converter const * PreviewLoader::Impl::pconverter_;
 265
 266
 267 //
 268 // The public interface, defined in PreviewLoader.h
 269 //
 270
 271 PreviewLoader::PreviewLoader(Buffer const & b)
 272         : pimpl_(new Impl(*this, b))
 273 {}
 274
 275
 276 PreviewLoader::~PreviewLoader()
 277 {
 278         delete pimpl_;
 279 }
 280
 281
 282 PreviewImage const * PreviewLoader::preview(string const & latex_snippet) const
 283 {
 284         return pimpl_->preview(latex_snippet);
 285 }
 286
 287
 288 PreviewLoader::Status PreviewLoader::status(string const & latex_snippet) const
 289 {
 290         return pimpl_->status(latex_snippet);
 291 }
 292
 293
 294 void PreviewLoader::add(string const & latex_snippet) const
 295 {
 296         pimpl_->add(latex_snippet);
 297 }
 298
 299
 300 void PreviewLoader::remove(string const & latex_snippet) const
 301 {
 302         pimpl_->remove(latex_snippet);
 303 }
 304
 305
 306 void PreviewLoader::addMacroDef(docstring const & latex_snippet) const
 307 {
 308         pimpl_->addMacroDef(latex_snippet);
 309 }
 310
 311
 312 bool PreviewLoader::hasMacroDef(docstring const & latex_snippet) const
 313 {
 314         return pimpl_->hasMacroDef(latex_snippet);
 315 }
 316
 317
 318 void PreviewLoader::startLoading(bool wait) const
 319 {
 320         pimpl_->startLoading(wait);
 321 }
 322
 323
 324 boost::signals::connection PreviewLoader::connect(slot_type const & slot) const
 325 {
 326         return pimpl_->imageReady.connect(slot);
 327 }
 328
 329
 330 void PreviewLoader::emitSignal(PreviewImage const & pimage) const
 331 {
 332         pimpl_->imageReady(pimage);
 333 }
 334
 335
 336 Buffer const & PreviewLoader::buffer() const
 337 {
 338         return pimpl_->buffer();
 339 }
 340
 341 } // namespace graphics
 342 } // namespace lyx
 343
 344
 345 // The details of the Impl
 346 // =======================
 347
 348 namespace {
 349
 350 class IncrementedFileName {
 351 public:
 352         IncrementedFileName(string const & to_format,
 353                             string const & filename_base)
 354                 : to_format_(to_format), base_(filename_base), counter_(1)
 355         {}
 356
 357         SnippetPair const operator()(string const & snippet)
 358         {
 359                 ostringstream os;
 360                 os << base_ << counter_++ << '.' << to_format_;
 361                 string const file = os.str();
 362
 363                 return make_pair(snippet, FileName(file));
 364         }
 365
 366 private:
 367         string const & to_format_;
 368         string const & base_;
 369         int counter_;
 370 };
 371
 372
 373 InProgress::InProgress(string const & filename_base,
 374                        PendingSnippets const & pending,
 375                        string const & to_format)
 376         : pid(0),
 377           metrics_file(filename_base + ".metrics"),
 378           snippets(pending.size())
 379 {
 380         PendingSnippets::const_iterator pit  = pending.begin();
 381         PendingSnippets::const_iterator pend = pending.end();
 382         BitmapFile::iterator sit = snippets.begin();
 383
 384         transform(pit, pend, sit,
 385                        IncrementedFileName(to_format, filename_base));
 386 }
 387
 388
 389 void InProgress::stop() const
 390 {
 391         if (pid)
 392                 ForkedCallsController::kill(pid, 0);
 393
 394         if (!metrics_file.empty())
 395                 metrics_file.removeFile();
 396
 397         BitmapFile::const_iterator vit  = snippets.begin();
 398         BitmapFile::const_iterator vend = snippets.end();
 399         for (; vit != vend; ++vit) {
 400                 if (!vit->second.empty())
 401                         vit->second.removeFile();
 402         }
 403 }
 404
 405 } // namespace anon
 406
 407
 408 namespace lyx {
 409 namespace graphics {
 410
 411 PreviewLoader::Impl::Impl(PreviewLoader & p, Buffer const & b)
 412         : parent_(p), buffer_(b)
 413 {
 414         font_scaling_factor_ = int(buffer_.fontScalingFactor());
 415         if (!pconverter_)
 416                 pconverter_ = setConverter("lyxpreview");
 417 }
 418
 419
 420 PreviewLoader::Impl::~Impl()
 421 {
 422         InProgressProcesses::iterator ipit  = in_progress_.begin();
 423         InProgressProcesses::iterator ipend = in_progress_.end();
 424
 425         for (; ipit != ipend; ++ipit)
 426                 ipit->second.stop();
 427 }
 428
 429
 430 PreviewImage const *
 431 PreviewLoader::Impl::preview(string const & latex_snippet) const
 432 {
 433         int fs = int(buffer_.fontScalingFactor());
 434         if (font_scaling_factor_ != fs) {
 435                 // Refresh all previews on zoom changes
 436                 font_scaling_factor_ = fs;
 437                 Cache::const_iterator cit = cache_.begin();
 438                 Cache::const_iterator cend = cache_.end();
 439                 while (cit != cend)
 440                         parent_.remove((cit++)->first);
 441                 buffer_.updatePreviews();
 442         }
 443         Cache::const_iterator it = cache_.find(latex_snippet);
 444         return (it == cache_.end()) ? 0 : it->second.get();
 445 }
 446
 447
 448 namespace {
 449
 450 class FindSnippet {
 451 public:
 452         FindSnippet(string const & s) : snippet_(s) {}
 453         bool operator()(InProgressProcess const & process) const
 454         {
 455                 BitmapFile const & snippets = process.second.snippets;
 456                 BitmapFile::const_iterator beg  = snippets.begin();
 457                 BitmapFile::const_iterator end = snippets.end();
 458                 return find_if(beg, end, FindFirst(snippet_)) != end;
 459         }
 460
 461 private:
 462         string const snippet_;
 463 };
 464
 465 } // namespace anon
 466
 467 PreviewLoader::Status
 468 PreviewLoader::Impl::status(string const & latex_snippet) const
 469 {
 470         Cache::const_iterator cit = cache_.find(latex_snippet);
 471         if (cit != cache_.end())
 472                 return Ready;
 473
 474         PendingSnippets::const_iterator pit  = pending_.begin();
 475         PendingSnippets::const_iterator pend = pending_.end();
 476
 477         pit = find(pit, pend, latex_snippet);
 478         if (pit != pend)
 479                 return InQueue;
 480
 481         InProgressProcesses::const_iterator ipit  = in_progress_.begin();
 482         InProgressProcesses::const_iterator ipend = in_progress_.end();
 483
 484         ipit = find_if(ipit, ipend, FindSnippet(latex_snippet));
 485         if (ipit != ipend)
 486                 return Processing;
 487
 488         return NotFound;
 489 }
 490
 491
 492 void PreviewLoader::Impl::add(string const & latex_snippet)
 493 {
 494         if (!pconverter_ || status(latex_snippet) != NotFound)
 495                 return;
 496
 497         string const snippet = trim(latex_snippet);
 498         if (snippet.empty())
 499                 return;
 500
 501         LYXERR(Debug::GRAPHICS, "adding snippet:\n" << snippet);
 502
 503         pending_.push_back(snippet);
 504 }
 505
 506
 507 namespace {
 508
 509 class EraseSnippet {
 510 public:
 511         EraseSnippet(string const & s) : snippet_(s) {}
 512         void operator()(InProgressProcess & process)
 513         {
 514                 BitmapFile & snippets = process.second.snippets;
 515                 BitmapFile::iterator it  = snippets.begin();
 516                 BitmapFile::iterator end = snippets.end();
 517
 518                 it = find_if(it, end, FindFirst(snippet_));
 519                 if (it != end)
 520                         snippets.erase(it, it+1);
 521         }
 522
 523 private:
 524         string const & snippet_;
 525 };
 526
 527 } // namespace anon
 528
 529
 530 void PreviewLoader::Impl::remove(string const & latex_snippet)
 531 {
 532         Cache::iterator cit = cache_.find(latex_snippet);
 533         if (cit != cache_.end())
 534                 cache_.erase(cit);
 535
 536         PendingSnippets::iterator pit  = pending_.begin();
 537         PendingSnippets::iterator pend = pending_.end();
 538
 539         pending_.erase(std::remove(pit, pend, latex_snippet), pend);
 540
 541         InProgressProcesses::iterator ipit  = in_progress_.begin();
 542         InProgressProcesses::iterator ipend = in_progress_.end();
 543
 544         for_each(ipit, ipend, EraseSnippet(latex_snippet));
 545
 546         while (ipit != ipend) {
 547                 InProgressProcesses::iterator curr = ipit++;
 548                 if (curr->second.snippets.empty())
 549                         in_progress_.erase(curr);
 550         }
 551 }
 552
 553
 554 void PreviewLoader::Impl::addMacroDef(docstring const & latex_snippet)
 555 {
 556         macrodefs_.insert(latex_snippet);
 557 }
 558
 559
 560 bool PreviewLoader::Impl::hasMacroDef(docstring const & latex_snippet) const
 561 {
 562         return macrodefs_.find(latex_snippet) != macrodefs_.end();
 563 }
 564
 565
 566 void PreviewLoader::Impl::startLoading(bool wait)
 567 {
 568         if (pending_.empty() || !pconverter_)
 569                 return;
 570
 571         // Only start the process off after the buffer is loaded from file.
 572         if (!buffer_.isFullyLoaded())
 573                 return;
 574
 575         LYXERR(Debug::GRAPHICS, "PreviewLoader::startLoading()");
 576
 577         // As used by the LaTeX file and by the resulting image files
 578         FileName const directory(buffer_.temppath());
 579
 580         FileName const latexfile = unique_tex_filename(directory);
 581         string const filename_base = removeExtension(latexfile.absFileName());
 582
 583         // Create an InProgress instance to place in the map of all
 584         // such processes if it starts correctly.
 585         InProgress inprogress(filename_base, pending_, pconverter_->to());
 586
 587         // clear pending_, so we're ready to start afresh.
 588         pending_.clear();
 589
 590         // Output the LaTeX file.
 591         // we use the encoding of the buffer
 592         Encoding const & enc = buffer_.params().encoding();
 593         ofdocstream of;
 594         try { of.reset(enc.iconvName()); }
 595         catch (iconv_codecvt_facet_exception const & e) {
 596                 LYXERR0("Caught iconv exception: " << e.what()
 597                         << "\nUnable to create LaTeX file: " << latexfile);
 598                 return;
 599         }
 600
 601         TexRow texrow;
 602         otexstream os(of, texrow);
 603         OutputParams runparams(&enc);
 604         LaTeXFeatures features(buffer_, buffer_.params(), runparams);
 605
 606         if (!openFileWrite(of, latexfile))
 607                 return;
 608
 609         if (!of) {
 610                 LYXERR(Debug::GRAPHICS, "PreviewLoader::startLoading()\n"
 611                                         << "Unable to create LaTeX file\n" << latexfile);
 612                 return;
 613         }
 614         of << "\\batchmode\n";
 615
 616         LYXERR(Debug::LATEX, "Format = " << buffer_.params().getDefaultOutputFormat());
 617         string latexparam = "";
 618         bool docformat = !buffer_.params().default_output_format.empty()
 619                         && buffer_.params().default_output_format != "default";
 620         // Use LATEX flavor if the document does not specify a specific
 621         // output format (see bug 9371).
 622         OutputParams::FLAVOR flavor = docformat
 623                                         ? buffer_.params().getOutputFlavor()
 624                                         : OutputParams::LATEX;
 625         if (buffer_.params().encoding().package() == Encoding::japanese) {
 626                 latexparam = " --latex=platex";
 627                 flavor = OutputParams::LATEX;
 628         }
 629         else if (buffer_.params().useNonTeXFonts) {
 630                 if (flavor == OutputParams::LUATEX)
 631                         latexparam = " --latex=lualatex";
 632                 else {
 633                         flavor = OutputParams::XETEX;
 634                         latexparam = " --latex=xelatex";
 635                 }
 636         }
 637         else {
 638                 switch (flavor) {
 639                         case OutputParams::PDFLATEX:
 640                                 latexparam = " --latex=pdflatex";
 641                                 break;
 642                         case OutputParams::XETEX:
 643                                 latexparam = " --latex=xelatex";
 644                                 break;
 645                         case OutputParams::LUATEX:
 646                                 latexparam = " --latex=lualatex";
 647                                 break;
 648                         case OutputParams::DVILUATEX:
 649                                 latexparam = " --latex=dvilualatex";
 650                                 break;
 651                         default:
 652                                 flavor = OutputParams::LATEX;
 653                 }
 654         }
 655         dumpPreamble(os, flavor);
 656         // handle inputenc etc.
 657         // I think, this is already hadled by dumpPreamble(): Kornel
 658         // buffer_.params().writeEncodingPreamble(os, features);
 659         of << "\n\\begin{document}\n";
 660         dumpData(of, inprogress.snippets);
 661         of << "\n\\end{document}\n";
 662         of.close();
 663         if (of.fail()) {
 664                 LYXERR(Debug::GRAPHICS, "PreviewLoader::startLoading()\n"
 665                                          << "File was not closed properly.");
 666                 return;
 667         }
 668
 669         // The conversion command.
 670         ostringstream cs;
 671         cs << pconverter_->command()
 672            << " " << quoteName(latexfile.toFilesystemEncoding())
 673            << " --dpi " << font_scaling_factor_;
 674
 675         // FIXME XHTML
 676         // The colors should be customizable.
 677         if (!buffer_.isExporting()) {
 678                 ColorCode const fg = PreviewLoader::foregroundColor();
 679                 ColorCode const bg = PreviewLoader::backgroundColor();
 680                 cs << " --fg " << theApp()->hexName(fg)
 681                    << " --bg " << theApp()->hexName(bg);
 682         }
 683
 684         cs << latexparam;
 685         if (buffer_.params().bibtex_command != "default")
 686                 cs << " --bibtex=" << quoteName(buffer_.params().bibtex_command);
 687         else if (buffer_.params().encoding().package() == Encoding::japanese)
 688                 cs << " --bibtex=" << quoteName(lyxrc.jbibtex_command);
 689         else
 690                 cs << " --bibtex=" << quoteName(lyxrc.bibtex_command);
 691         if (buffer_.params().bufferFormat() == "lilypond-book")
 692                 cs << " --lilypond";
 693
 694         string const command = cs.str();
 695
 696         if (wait) {
 697                 ForkedCall call(buffer_.filePath(), buffer_.layoutPos());
 698                 int ret = call.startScript(ForkedProcess::Wait, command);
 699                 // FIXME THREAD
 700                 static int fake = (2^20) + 1;
 701                 int pid = fake++;
 702                 inprogress.pid = pid;
 703                 inprogress.command = command;
 704                 in_progress_[pid] = inprogress;
 705                 finishedGenerating(pid, ret);
 706                 return;
 707         }
 708
 709         // Initiate the conversion from LaTeX to bitmap images files.
 710         ForkedCall::SignalTypePtr
 711                 convert_ptr(new ForkedCall::SignalType);
 712         convert_ptr->connect(bind(&Impl::finishedGenerating, this, _1, _2));
 713
 714         ForkedCall call(buffer_.filePath());
 715         int ret = call.startScript(command, convert_ptr);
 716
 717         if (ret != 0) {
 718                 LYXERR(Debug::GRAPHICS, "PreviewLoader::startLoading()\n"
 719                                         << "Unable to start process\n" << command);
 720                 return;
 721         }
 722
 723         // Store the generation process in a list of all such processes
 724         inprogress.pid = call.pid();
 725         inprogress.command = command;
 726         in_progress_[inprogress.pid] = inprogress;
 727 }
 728
 729
 730 double PreviewLoader::displayPixelRatio() const
 731 {
 732         return buffer().params().display_pixel_ratio;
 733 }
 734
 735 void PreviewLoader::Impl::finishedGenerating(pid_t pid, int retval)
 736 {
 737         // Paranoia check!
 738         InProgressProcesses::iterator git = in_progress_.find(pid);
 739         if (git == in_progress_.end()) {
 740                 lyxerr << "PreviewLoader::finishedGenerating(): unable to find "
 741                         "data for PID " << pid << endl;
 742                 return;
 743         }
 744
 745         string const command = git->second.command;
 746         string const status = retval > 0 ? "failed" : "succeeded";
 747         LYXERR(Debug::GRAPHICS, "PreviewLoader::finishedInProgress("
 748                                 << retval << "): processing " << status
 749                                 << " for " << command);
 750         if (retval > 0)
 751                 return;
 752
 753         // Read the metrics file, if it exists
 754         vector<double> ascent_fractions(git->second.snippets.size());
 755         setAscentFractions(ascent_fractions, git->second.metrics_file);
 756
 757         // Add these newly generated bitmap files to the cache and
 758         // start loading them into LyX.
 759         BitmapFile::const_iterator it  = git->second.snippets.begin();
 760         BitmapFile::const_iterator end = git->second.snippets.end();
 761
 762         list<PreviewImagePtr> newimages;
 763
 764         int metrics_counter = 0;
 765         for (; it != end; ++it, ++metrics_counter) {
 766                 string const & snip = it->first;
 767                 FileName const & file = it->second;
 768                 double af = ascent_fractions[metrics_counter];
 769
 770                 // Add the image to the cache only if it's actually present
 771                 // and not empty (an empty image is signaled by af < 0)
 772                 if (af >= 0 && file.isReadableFile()) {
 773                         PreviewImagePtr ptr(new PreviewImage(parent_, snip, file, af));
 774                         cache_[snip] = ptr;
 775
 776                         newimages.push_back(ptr);
 777                 }
 778
 779         }
 780
 781         // Remove the item from the list of still-executing processes.
 782         in_progress_.erase(git);
 783
 784         // Tell the outside world
 785         list<PreviewImagePtr>::const_reverse_iterator
 786                 nit  = newimages.rbegin();
 787         list<PreviewImagePtr>::const_reverse_iterator
 788                 nend = newimages.rend();
 789         for (; nit != nend; ++nit) {
 790                 imageReady(*nit->get());
 791         }
 792 }
 793
 794
 795 void PreviewLoader::Impl::dumpPreamble(otexstream & os, OutputParams::FLAVOR flavor) const
 796 {
 797         // Dump the preamble only.
 798         LYXERR(Debug::LATEX, "dumpPreamble, flavor == " << flavor);
 799         OutputParams runparams(&buffer_.params().encoding());
 800         runparams.flavor = flavor;
 801         runparams.nice = true;
 802         runparams.moving_arg = true;
 803         runparams.free_spacing = true;
 804         runparams.is_child = buffer_.parent();
 805         buffer_.writeLaTeXSource(os, buffer_.filePath(), runparams, Buffer::OnlyPreamble);
 806
 807         // FIXME! This is a HACK! The proper fix is to control the 'true'
 808         // passed to WriteStream below:
 809         // int InsetMathNest::latex(Buffer const &, odocstream & os,
 810         //                          OutputParams const & runparams) const
 811         // {
 812         //      WriteStream wi(os, runparams.moving_arg, true);
 813         //      par_->write(wi);
 814         //      return wi.line();
 815         // }
 816         os << "\n"
 817            << "\\def\\lyxlock{}\n"
 818            << "\n";
 819
 820         // All equation labels appear as "(#)" + preview.sty's rendering of
 821         // the label name
 822         if (lyxrc.preview_hashed_labels)
 823                 os << "\\renewcommand{\\theequation}{\\#}\n";
 824
 825         // Use the preview style file to ensure that each snippet appears on a
 826         // fresh page.
 827         // Also support PDF output (automatically generated e.g. when
 828         // \usepackage[pdftex]{hyperref} is used and XeTeX.
 829         os << "\n"
 830            << "\\usepackage[active,delayed,showlabels,lyx]{preview}\n"
 831            << "\n";
 832 }
 833
 834
 835 void PreviewLoader::Impl::dumpData(odocstream & os,
 836                                    BitmapFile const & vec) const
 837 {
 838         if (vec.empty())
 839                 return;
 840
 841         BitmapFile::const_iterator it  = vec.begin();
 842         BitmapFile::const_iterator end = vec.end();
 843
 844         for (; it != end; ++it) {
 845                 // FIXME UNICODE
 846                 os << "\\begin{preview}\n"
 847                    << from_utf8(it->first)
 848                    << "\n\\end{preview}\n\n";
 849         }
 850 }
 851
 852 } // namespace graphics
 853 } // namespace lyx