Porting the pre-92 file update message from 0.92.x to trunk:

New dialog when opening pre-0.92 files (with 90 dpi). 
I implemented it mostly based on mizmo's UI proposal (thanks!), with additional inputs from su_v with a few bugfixes from jabiertxof
Also adds a commandline option --convert-dpi-method=[none|scale-viewbox|scale-document] to be able to batch convert files.

Fixed bugs:
  - https://launchpad.net/bugs/1659229

(bzr r15729)

5 files changed, 477 insertions, 533 deletions

diff --git a/src/document.cpp b/src/document.cpp
index 4fcc2b098..2141f65e9 100644
--- a/src/document.cpp
+++ b/src/document.cpp
@@ -469,6 +469,11 @@ SPDocument *SPDocument::createDoc(Inkscape::XML::Document *rdoc,
         sp_file_convert_font_name(document);
     }
 
+    /** Fix dpi (pre-92 files) **/
+    if ( !(INKSCAPE.use_gui()) && sp_version_inside_range( document->root->version.inkscape, 0, 1, 0, 92 ) ) {
+        sp_file_convert_dpi(document);
+    }
+
     return document;
 }
 
diff --git a/src/file-update.cpp b/src/file-update.cpp
index 8fb3b3111..c9a1b6d62 100644
--- a/src/file-update.cpp
+++ b/src/file-update.cpp
@@ -8,6 +8,17 @@
  * Marc Jeanmougin
  * su_v
  */
+#include <gtkmm.h>
+
+#include "extension/effect.h"
+#include "extension/db.h"
+#include "extension/input.h"
+#include "extension/output.h"
+#include "extension/system.h"
+
+#include "inkscape.h"
+#include "preferences.h"
+
 #include "file.h"
 #include "sp-root.h"
 #include "sp-text.h"
@@ -17,13 +28,33 @@
 #include "sp-object.h"
 #include "sp-item.h"
 #include "style.h"
+#include "sp-defs.h"
+#include "dir-util.h"
 #include "document.h"
 #include <string>
 #include <clocale>
 #include "text-editing.h"
-
+#include "document-undo.h"
+#include "display/canvas-grid.h"
+#include "sp-guide.h"
+#include "selection-chemistry.h"
+#include "persp3d.h"
+#include "proj_pt.h"
+#include "ui/shape-editor.h"
+#include "io/sys.h"
+#include "print.h"
+#include "ui/interface.h"
+#include "desktop.h"
+#include "message.h"
+#include "message-stack.h"
+#include "verbs.h"
+#include "sp-namedview.h"
+ 
+using Inkscape::DocumentUndo;
 using namespace std;
 
+int sp_file_convert_dpi_method_commandline = -1; // Unset
+
 bool is_line(SPObject *i)
 {
     if (!(i->getAttribute("sodipodi:role")))
@@ -167,6 +198,416 @@ void sp_file_convert_font_name(SPDocument *doc)
     sp_file_text_run_recursive(fix_update, doc->getRoot());
 }
 
+
+// Quick and dirty internal backup function
+bool sp_file_save_backup( Glib::ustring uri ) {
+
+    Glib::ustring out = uri;
+    out.insert(out.find(".svg"),"_backup");
+
+    FILE *filein  = Inkscape::IO::fopen_utf8name(uri.c_str(), "rb");
+    if (!filein) {
+        std::cerr << "sp_file_save_backup: failed to open: " << uri << std::endl;
+        return false;
+    }
+
+    FILE *fileout = Inkscape::IO::fopen_utf8name(out.c_str(), "wb");
+    if (!fileout) {
+        std::cerr << "sp_file_save_backup: failed to open: " << out << std::endl;
+        fclose( filein );
+        return false;
+    }
+
+    int ch;
+    while ((ch = fgetc(filein)) != EOF) {
+        fputc(ch, fileout);
+    }
+    fflush(fileout);
+
+    bool return_value = true;
+    if (ferror(fileout)) {
+        std::cerr << "sp_file_save_backup: error when writing to: " << out << std::endl;
+        return_value = false;
+    }
+
+    fclose(filein);
+    fclose(fileout);
+
+    return return_value;
+}
+
+
+void sp_file_convert_dpi(SPDocument *doc)
+{
+    Inkscape::Preferences *prefs = Inkscape::Preferences::get();
+    Glib::ustring uri = doc->getURI();
+    SPRoot *root = doc->getRoot();
+
+    // See if we need to offer the user a fix for the 90->96 px per inch change.
+    // std::cout << "SPFileOpen:" << std::endl;
+    // std::cout << "  Version: " << sp_version_to_string(root->version.inkscape) << std::endl;
+    // std::cout << "  SVG file from old Inkscape version detected: "                          
+    //           << sp_version_to_string(root->version.inkscape) << std::endl;                 
+    static const double ratio = 90.0/96.0;
+
+    bool need_fix_viewbox = false;
+    bool need_fix_units   = false;
+    bool need_fix_guides  = false;
+    bool need_fix_grid_mm = false;
+    bool need_fix_box3d   = false;
+    bool did_scaling      = false;
+
+    // Check if potentially need viewbox or unit fix                                           
+    switch (root->width.unit) {
+        case SP_CSS_UNIT_PC:
+        case SP_CSS_UNIT_PT:
+        case SP_CSS_UNIT_MM:
+        case SP_CSS_UNIT_CM:
+        case SP_CSS_UNIT_IN:
+            need_fix_viewbox = true;
+            break;
+        case SP_CSS_UNIT_NONE:
+        case SP_CSS_UNIT_PX:
+            need_fix_units = true;
+            break;
+        case SP_CSS_UNIT_EM:
+        case SP_CSS_UNIT_EX:
+        case SP_CSS_UNIT_PERCENT:
+            // OK                                                                              
+            break;
+        default:
+            std::cerr << "sp_file_open: Unhandled width unit!" << std::endl;
+    }
+
+    switch (root->height.unit) {
+        case SP_CSS_UNIT_PC:
+        case SP_CSS_UNIT_PT:
+        case SP_CSS_UNIT_MM:
+        case SP_CSS_UNIT_CM:
+        case SP_CSS_UNIT_IN:
+            need_fix_viewbox = true;
+            break;
+        case SP_CSS_UNIT_NONE:
+        case SP_CSS_UNIT_PX:
+            need_fix_units = true;
+            break;
+        case SP_CSS_UNIT_EM:
+        case SP_CSS_UNIT_EX:
+        case SP_CSS_UNIT_PERCENT:
+            // OK                                                                              
+            break;
+        default:
+            std::cerr << "sp_file_open: Unhandled height unit!" << std::endl;
+    }
+
+    if (need_fix_units && need_fix_viewbox) {
+        std::cerr << "Different units in document size !" << std::endl;
+        if (root->viewBox_set)
+            need_fix_viewbox = false;
+        else
+            need_fix_units = false;
+    }
+
+    // std::cout << "Absolute SVG units in root? " << (need_fix_viewbox?"true":"false") << std::endl;                 
+    // std::cout << "User units in root? "         << (need_fix_units  ?"true":"false") << std::endl;                 
+
+    if ((!root->viewBox_set && need_fix_viewbox) || need_fix_units) {
+        int response = FILE_DPI_UNCHANGED; // default
+
+        /******** UI *******/
+        bool backup = prefs->getBool("/options/dpifixbackup", true);
+        if (INKSCAPE.use_gui() && sp_file_convert_dpi_method_commandline == -1) {
+            Gtk::Dialog scale_dialog(_("Convert legacy Inkscape file"));
+            scale_dialog.set_border_width(10);
+            scale_dialog.set_resizable(false);
+            Gtk::Label explanation;
+            explanation.set_markup(Glib::ustring("<b>") + doc->getName() + "</b>\n" +
+                                   _("was created in an older version of Inkscape (90 DPI) and we need "
+                                     "to make it compatible with newer versions (96 DPI). Tell us about this file:\n"));
+            explanation.set_line_wrap(true);
+            explanation.set_size_request(600,-1);
+            Gtk::RadioButton::Group c1, c2;
+
+            Gtk::Label choice1_label;
+            choice1_label.set_markup(
+                _("This file contains digital artwork for screen display. <b>(Choose if unsure.)</b>"));
+            Gtk::RadioButton choice1(c1);
+            choice1.add(choice1_label);
+            Gtk::RadioButton choice2(c1, _("This file is intended for physical output, such as paper or 3D prints."));
+            Gtk::Label choice2_1_label;
+            choice2_1_label.set_markup(_("The appearance of elements such as clips, masks, filters, and clones\n"
+                                         "is most important. <b>(Choose if unsure.)</b>"));
+            Gtk::RadioButton choice2_1(c2);
+            choice2_1.add(choice2_1_label);
+            Gtk::RadioButton choice2_2(c2, _("The accuracy of the physical unit size and position values of objects\n"
+                                             "in the file is most important. (Experimental.)"));
+            Gtk::CheckButton backup_button(_("Create a backup file in same directory."));
+            Gtk::Expander moreinfo(_("More details..."));
+            Gtk::Label moreinfo_text;
+            moreinfo_text.set_markup(
+                _("<small>We've updated Inkscape to follow the CSS standard of 96 DPI for better browser "
+                  "compatibility; we used to use 90 DPI. "
+                  "Digital artwork for screen display will be converted to 96 DPI without scaling and should be "
+                  "unaffected. "
+                  "Artwork drawn at 90 DPI for a specific physical size will be too small if converted to 96 DPI "
+                  "without any scaling. There are two scaling methods:\n\n"
+                  "<b>Scaling the whole document:</b> The least error-prone method, this preserves the appearance of "
+                  "the artwork, including filters and the position of masks, etc. "
+                  "The scale of the artwork relative to the document size may not be accurate.\n\n"
+                  "<b>Scaling individual elements in the artwork:</b> This method is less reliable and can result in "
+                  "a changed appearance, "
+                  "but is better for physical output that relies on accurate sizes and positions (for example, for "
+                  "3D printing.)\n\n"
+                  "More information about this change are available in the <a "
+                  "href='https://inkscape.org/en/learn/faq#todo-todo-todo'>Inkscape FAQ</a>"
+                  "</small>"));
+            moreinfo_text.set_line_wrap(true);
+            moreinfo_text.set_size_request(554,-1);
+            Gtk::Box b;
+            b.set_border_width(0);
+            
+            b.pack_start(choice2_1, false, false, 4);
+            b.pack_start(choice2_2, false, false, 4);
+            choice2_1.show();
+            choice2_2.show();
+
+            Gtk::Alignment balign(0, 0, 0, 0);
+            balign.set_padding (0, 0, 30, 0);
+            balign.show();
+            balign.add(b);
+            Gtk::Box *content = scale_dialog.get_content_area();
+            content->pack_start(explanation, false, false, 5);
+            content->pack_start(choice1, false, false, 5);
+            content->pack_start(choice2, false, false, 5);
+            content->pack_start(balign, false, false, 5);
+            content->pack_start(backup_button, false, false, 5);
+            Gtk::Button *ok_button = scale_dialog.add_button(_("OK"), GTK_RESPONSE_ACCEPT);
+            backup_button.set_active(backup);
+            content->pack_start(moreinfo, false, false, 5);
+            moreinfo.add(moreinfo_text);
+            scale_dialog.show_all_children();
+            b.hide();
+            choice1.signal_clicked().connect(sigc::mem_fun(b, &Gtk::Box::hide));
+            choice2.signal_clicked().connect(sigc::mem_fun(b, &Gtk::Box::show));
+
+            response = prefs->getInt("/options/dpiupdatemethod", FILE_DPI_UNCHANGED);
+            if ( response != FILE_DPI_UNCHANGED ) {
+                choice2.set_active();
+                b.show();
+                if ( response == FILE_DPI_DOCUMENT_SCALED)
+                    choice2_2.set_active();
+            }
+            ok_button->grab_focus();
+
+            int status = scale_dialog.run();
+            if ( status == GTK_RESPONSE_ACCEPT ) {
+                backup = backup_button.get_active();
+                prefs->setBool("/options/dpifixbackup", backup);
+                response = choice1.get_active() ? FILE_DPI_UNCHANGED : choice2_1.get_active() ? FILE_DPI_VIEWBOX_SCALED : FILE_DPI_DOCUMENT_SCALED;
+                prefs->setInt("/options/dpiupdatemethod", response);
+            } else if (sp_file_convert_dpi_method_commandline != -1) {
+                response = sp_file_convert_dpi_method_commandline;
+            } else {
+                response = FILE_DPI_UNCHANGED;
+            }
+        } else { // GUI with explicit option
+            response = FILE_DPI_UNCHANGED;
+        }
+
+        if (backup && (response != FILE_DPI_UNCHANGED)) {
+            sp_file_save_backup(uri);
+        }
+
+        if (!(response == FILE_DPI_UNCHANGED && need_fix_units)) {
+            need_fix_guides = true; // Only fix guides if drawing scaled
+            need_fix_box3d = true;
+        }
+
+        if (response == FILE_DPI_VIEWBOX_SCALED) {
+            double ratio_viewbox = need_fix_units ? 1.0 : ratio;
+
+            doc->setViewBox(Geom::Rect::from_xywh(0, 0, doc->getWidth().value("px") * ratio_viewbox,
+                                                  doc->getHeight().value("px") * ratio_viewbox));
+            Inkscape::Util::Quantity width = // maybe set it to mm ?
+                Inkscape::Util::Quantity(doc->getWidth().value("px") / ratio, "px");
+            Inkscape::Util::Quantity height = Inkscape::Util::Quantity(doc->getHeight().value("px") / ratio, "px");
+            if (need_fix_units)
+                doc->setWidthAndHeight(width, height, false);
+
+            } else if (response == FILE_DPI_DOCUMENT_SCALED) {
+
+            Inkscape::Util::Quantity width = // maybe set it to mm ?
+                Inkscape::Util::Quantity(doc->getWidth().value("px") / ratio, "px");
+            Inkscape::Util::Quantity height = Inkscape::Util::Quantity(doc->getHeight().value("px") / ratio, "px");
+            if (need_fix_units)
+                doc->setWidthAndHeight(width, height, false);
+
+            if (!root->viewBox_set) {
+                // Save preferences
+                bool transform_stroke = prefs->getBool("/options/transform/stroke", true);
+                bool transform_rectcorners = prefs->getBool("/options/transform/rectcorners", true);
+                bool transform_pattern = prefs->getBool("/options/transform/pattern", true);
+                bool transform_gradient = prefs->getBool("/options/transform/gradient", true);
+
+                prefs->setBool("/options/transform/stroke", true);
+                prefs->setBool("/options/transform/rectcorners", true);
+                prefs->setBool("/options/transform/pattern", true);
+                prefs->setBool("/options/transform/gradient", true);
+
+                Inkscape::UI::ShapeEditor::blockSetItem(true);
+                doc->getRoot()->scaleChildItemsRec(Geom::Scale(1 / ratio), Geom::Point(0, 0), false);
+                Inkscape::UI::ShapeEditor::blockSetItem(false);
+
+                // Restore preferences
+                prefs->setBool("/options/transform/stroke", transform_stroke);
+                prefs->setBool("/options/transform/rectcorners", transform_rectcorners);
+                prefs->setBool("/options/transform/pattern", transform_pattern);
+                prefs->setBool("/options/transform/gradient", transform_gradient);
+
+                did_scaling = true;
+/*
+
+// There used to be 2 "experimental" scaling methods in trunk. Considering that the method in .92.x appear to work, so I'm commenting those.
+
+                // Save preferences
+                Inkscape::Preferences *prefs = Inkscape::Preferences::get();
+                bool onlysensitive = prefs->getBool("/options/kbselection/onlysensitive",true);
+                bool onlyvisible   = prefs->getBool("/options/kbselection/onlyvisible",  true);
+
+                prefs->setBool("/options/kbselection/onlysensitive", false);
+                prefs->setBool("/options/kbselection/onlyvisible",   false);
+
+                Inkscape::Selection *selection = desktop->getSelection();
+                Inkscape::SelectionHelper::selectAllInAll( desktop );
+                            
+//method 1 ...
+                selection->group();
+                SPItem * group = selection->singleItem();
+                if (group) {
+                    group->setAttribute("transform","scale(1.06666667,1.06666667)");
+                } else {
+                    std::cerr << "sp_file_open: Failed to get group!" << std::endl;
+                }
+                selection->clear();
+                selection->add( group );
+                selection->ungroup();
+                            
+// OR method 2...                            
+
+                double height = root->height.computed;
+                selection->setScaleRelative( Geom::Point(0,height), Geom::Scale(96.0/90.0,96.0/90.0) );
+
+... end method 2
+
+                selection->clear();
+
+                prefs->setBool("/options/kbselection/onlysensitive", onlysensitive);
+                prefs->setBool("/options/kbselection/onlyvisible",   onlyvisible  );
+
+                did_scaling = true;
+*/
+
+
+
+            }
+        } else { // FILE_DPI_UNCHANGED
+            if (need_fix_units)
+                need_fix_grid_mm = true;
+        }
+    }
+
+    // Fix guides and grids and perspective
+    for (SPObject *child = root->firstChild(); child; child = child->getNext()) {
+        SPNamedView *nv = dynamic_cast<SPNamedView *>(child);
+        if (nv) {
+            if (need_fix_guides) {
+                // std::cout << "Fixing guides" << std::endl;
+                for (SPObject *child2 = nv->firstChild(); child2; child2 = child2->getNext()) {
+                    SPGuide *gd = dynamic_cast<SPGuide *>(child2);
+                    if (gd) {
+                        gd->moveto(gd->getPoint() / ratio, true);
+                    }
+                }
+            }
+
+            for (std::vector<Inkscape::CanvasGrid *>::const_iterator it = nv->grids.begin(); it != nv->grids.end();
+                 ++it) {
+                Inkscape::CanvasXYGrid *xy = dynamic_cast<Inkscape::CanvasXYGrid *>(*it);
+                if (xy) {
+                    // std::cout << "A grid: " << xy->getSVGName() << std::endl;
+                    // std::cout << "  Origin: " << xy->origin
+                    //           << "  Spacing: " << xy->spacing << std::endl;
+                    // std::cout << (xy->isLegacy()?"  Legacy":"  Not Legacy") << std::endl;
+                    Geom::Scale scale = doc->getDocumentScale();
+                    if (xy->isLegacy()) {
+                        if (xy->isPixel()) {
+                            if (need_fix_grid_mm) {
+                                xy->Scale(Geom::Scale(1, 1)); // See note below
+                            } else {
+                                scale *= Geom::Scale(ratio, ratio);
+                                xy->Scale(scale.inverse()); /* *** */
+                            }
+                        } else {
+                            if (need_fix_grid_mm) {
+                                xy->Scale(Geom::Scale(ratio, ratio));
+                            } else {
+                                xy->Scale(scale.inverse()); /* *** */
+                            }
+                        }
+                    } else {
+                        if (need_fix_guides) {
+                            if (did_scaling) {
+                                xy->Scale(Geom::Scale(ratio, ratio).inverse());
+                            } else {
+                                // HACK: Scaling the document does not seem to cause
+                                // grids defined in document units to be updated.
+                                // This forces an update.
+                                xy->Scale(Geom::Scale(1, 1));
+                            }
+                        }
+                    }
+                }
+            }
+        } // If SPNamedView
+
+        SPDefs *defs = dynamic_cast<SPDefs *>(child);
+        if (defs && need_fix_box3d) {
+            for (SPObject *child = defs->firstChild(); child; child = child->getNext()) {
+                Persp3D *persp3d = dynamic_cast<Persp3D *>(child);
+                if (persp3d) {
+                    std::vector<Glib::ustring> tokens;
+
+                    const gchar *vp_x = persp3d->getAttribute("inkscape:vp_x");
+                    const gchar *vp_y = persp3d->getAttribute("inkscape:vp_y");
+                    const gchar *vp_z = persp3d->getAttribute("inkscape:vp_z");
+                    const gchar *vp_o = persp3d->getAttribute("inkscape:persp3d-origin");
+                    // std::cout << "Found Persp3d: "
+                    //           << " vp_x: " << vp_x
+                    //           << " vp_y: " << vp_y
+                    //           << " vp_z: " << vp_z << std::endl;
+                    Proj::Pt2 pt_x(vp_x);
+                    Proj::Pt2 pt_y(vp_y);
+                    Proj::Pt2 pt_z(vp_z);
+                    Proj::Pt2 pt_o(vp_o);
+                    pt_x = pt_x * (1.0 / ratio);
+                    pt_y = pt_y * (1.0 / ratio);
+                    pt_z = pt_z * (1.0 / ratio);
+                    pt_o = pt_o * (1.0 / ratio);
+                    persp3d->setAttribute("inkscape:vp_x", pt_x.coord_string());
+                    persp3d->setAttribute("inkscape:vp_y", pt_y.coord_string());
+                    persp3d->setAttribute("inkscape:vp_z", pt_z.coord_string());
+                    persp3d->setAttribute("inkscape:persp3d-origin", pt_o.coord_string());
+                }
+            }
+        }
+    } // Look for SPNamedView and SPDefs loop
+
+    // desktop->getDocument()->ensureUpToDate();  // Does not update box3d!
+    DocumentUndo::done(doc, SP_VERB_NONE, _("Update Document"));
+}
+
+
+
 /*
   Local Variables:
   mode:c++
diff --git a/src/file.cpp b/src/file.cpp
index 795df433d..43a9c6f5b 100644
--- a/src/file.cpp
+++ b/src/file.cpp
@@ -65,13 +65,6 @@
 #include "event-log.h"
 #include "ui/dialog/font-substitution.h"
 
-// For updating old Inkscape SVG files
-#include "display/canvas-grid.h"
-#include "sp-guide.h"
-#include "selection-chemistry.h"
-#include "persp3d.h"
-#include "proj_pt.h"
-#include "ui/shape-editor.h"
 
 using Inkscape::DocumentUndo;
 
@@ -240,42 +233,6 @@ sp_file_exit()
 }
 
 
-// Quick and dirty internal backup function
-bool sp_file_save_backup( Glib::ustring uri ) {
-
-    Glib::ustring out = uri;
-    out.insert(out.find(".svg"),"_backup");
-
-    FILE *filein  = Inkscape::IO::fopen_utf8name(uri.c_str(), "rb");
-    if (!filein) {
-        std::cerr << "sp_file_save_backup: failed to open: " << uri << std::endl;
-        return false;
-    }
-
-    FILE *fileout = Inkscape::IO::fopen_utf8name(out.c_str(), "wb");
-    if (!fileout) {
-        std::cerr << "sp_file_save_backup: failed to open: " << out << std::endl;
-        fclose( filein );
-        return false;
-    }
-
-    int ch;
-    while ((ch = fgetc(filein)) != EOF) {
-        fputc(ch, fileout);
-    }
-    fflush(fileout);
-
-    bool return_value = true;
-    if (ferror(fileout)) {
-        std::cerr << "sp_file_save_backup: error when writing to: " << out << std::endl;
-        return_value = false;
-    }
-
-    fclose(filein);
-    fclose(fileout);
-
-    return return_value;
-}
 
 /*######################
 ## O P E N
@@ -342,497 +299,12 @@ bool sp_file_open(const Glib::ustring &uri,
         root->original.svg      = root->version.svg;
 
         if (INKSCAPE.use_gui()) {
-
-            // See if we need to offer the user a fix for the 90->96 px per inch change.
-            // std::cout << "SPFileOpen:" << std::endl;
-            // std::cout << "  Version: " << sp_version_to_string(root->version.inkscape) << std::endl;
-
-            if ( sp_version_inside_range( root->version.inkscape, 0, 1, 0, 92 ) ) {
-
-                // std::cout << "  SVG file from old Inkscape version detected: "
-                //           << sp_version_to_string(root->version.inkscape) << std::endl;
-                static const double ratio = 90.0/96.0;
-
-                bool need_fix_viewbox = false;
-                bool need_fix_units   = false;
-                bool need_fix_guides  = false;
-                bool need_fix_grid_mm = false;
-                bool need_fix_box3d   = false;
-                bool did_scaling = false;
-
-                // Check if potentially need viewbox or unit fix
-                switch (root->width.unit) {
-                    case SP_CSS_UNIT_PC:
-                    case SP_CSS_UNIT_PT:
-                    case SP_CSS_UNIT_MM:
-                    case SP_CSS_UNIT_CM:
-                    case SP_CSS_UNIT_IN:
-                        need_fix_viewbox = true;
-                        break;
-                    case SP_CSS_UNIT_NONE:
-                    case SP_CSS_UNIT_PX:
-                        need_fix_units = true;
-                        break;
-                    case SP_CSS_UNIT_EM:
-                    case SP_CSS_UNIT_EX:
-                    case SP_CSS_UNIT_PERCENT:
-                        // OK
-                        break;
-                    default:
-                        std::cerr << "sp_file_open: Unhandled width unit!" << std::endl;
-                }
-
-                switch (root->height.unit) {
-                    case SP_CSS_UNIT_PC:
-                    case SP_CSS_UNIT_PT:
-                    case SP_CSS_UNIT_MM:
-                    case SP_CSS_UNIT_CM:
-                    case SP_CSS_UNIT_IN:
-                        need_fix_viewbox = true;
-                        break;
-                    case SP_CSS_UNIT_NONE:
-                    case SP_CSS_UNIT_PX:
-                        need_fix_units = true;
-                        break;
-                    case SP_CSS_UNIT_EM:
-                    case SP_CSS_UNIT_EX:
-                    case SP_CSS_UNIT_PERCENT:
-                        // OK
-                        break;
-                    default:
-                        std::cerr << "sp_file_open: Unhandled height unit!" << std::endl;
-                }
-
-                // std::cout << "Absolute SVG units in root? " << (need_fix_viewbox?"true":"false") << std::endl;
-                // std::cout << "User units in root? "         << (need_fix_units  ?"true":"false") << std::endl;
-
-                Inkscape::Preferences *prefs = Inkscape::Preferences::get();
-
-                if (!root->viewBox_set && need_fix_viewbox) {
-
-                    Glib::ustring msg = _(
-                        "Old Inkscape files use 1in == 90px. CSS requires 1in == 96px.\n"
-                        "Drawing elements may be too small. This can be corrected by\n"
-                        "either setting the SVG 'viewBox' to compensate or by scaling\n"
-                        "all the elements in the drawing.");
-                    Gtk::Dialog scaleDialog( _("Old Inkscape file detected (90 DPI)"), false);
-
-                    Gtk::Label info;
-                    info.set_markup(msg.c_str());
-                    info.show();
-                    scaleDialog.get_content_area()->pack_start(info, false, false, 20);
-
-                    Gtk::CheckButton backupButton( _("Create backup file (in same directory).") );
-                    bool backup = prefs->getBool("/options/dpifixbackup", true);
-                    backupButton.set_active( backup );
-                    backupButton.show();
-                    scaleDialog.get_content_area()->pack_start(backupButton, false, false, 20);
-
-                    scaleDialog.add_button(_("Set 'viewBox'"),   1);
-                    scaleDialog.add_button(_("Scale elements"),  2);
-                    scaleDialog.add_button(_("Ignore"),          3);
-                    scaleDialog.add_button("Scale test - group",    4);
-                    scaleDialog.add_button("Scale test - children", 5);
-                    scaleDialog.add_button("Scale test - all",      6);
-
-                    gint response = scaleDialog.run();
-                    backup = backupButton.get_active();
-                    prefs->setBool("/options/dpifixbackup", backup);
-
-                    if ( backup && response != 3) {
-                        sp_file_save_backup( uri );
-                    }
-
-                    if (response == 1) {
-
-                        doc->setViewBox(Geom::Rect::from_xywh(
-                                            0, 0,
-                                            doc->getWidth().value("px") * ratio,
-                                            doc->getHeight().value("px") * ratio));
-
-                    } else if (response == 2 ) {
-
-                        std::list<Inkscape::Extension::Effect *> effects;
-                        Inkscape::Extension::db.get_effect_list(effects);
-                        std::list<Inkscape::Extension::Effect *>::iterator it = effects.begin();
-                        bool did = false;
-                        while (it != effects.end()) {
-                            if (strcmp((*it)->get_id(), "org.inkscape.dpi90to96") == 0) {
-                                Inkscape::UI::View::View *view = desktop;
-                                (*it)->effect(view);
-                                did = true;
-                                break;
-                            }
-                            ++it;
-                        }
-                        if (!did) {
-                            std::cerr << "sp_file_open: Failed to find dpi90to96 extension." << std::endl;
-                        }
-                        did_scaling = true;
-
-                    } else if (response == 4) {
-
-                        // Save preferences
-                        bool onlysensitive = prefs->getBool("/options/kbselection/onlysensitive",true);
-                        bool onlyvisible   = prefs->getBool("/options/kbselection/onlyvisible",  true);
-
-                        prefs->setBool("/options/kbselection/onlysensitive", false);
-                        prefs->setBool("/options/kbselection/onlyvisible",   false);
-
-                        Inkscape::Selection *selection = desktop->getSelection();
-                        Inkscape::SelectionHelper::selectAllInAll( desktop );
-                        selection->group();
-                        SPItem * group = selection->singleItem();
-                        if (group) {
-                            group->setAttribute("transform","scale(1.06666667,1.06666667)");
-                        } else {
-                            std::cerr << "sp_file_open: Failed to get group!" << std::endl;
-                        }
-                        selection->clear();
-                        selection->add( group );
-                        selection->ungroup();
-                        selection->clear();
-
-                        prefs->setBool("/options/kbselection/onlysensitive", onlysensitive);
-                        prefs->setBool("/options/kbselection/onlyvisible",   onlyvisible  );
-
-                        did_scaling = true;
-
-                    } else if (response == 5) {
-
-                        // Save preferences
-                        bool transform_stroke      = prefs->getBool("/options/transform/stroke", true);
-                        bool transform_rectcorners = prefs->getBool("/options/transform/rectcorners", true);
-                        bool transform_pattern     = prefs->getBool("/options/transform/pattern", true);
-                        bool transform_gradient    = prefs->getBool("/options/transform/gradient", true);
-
-                        prefs->setBool("/options/transform/stroke",      true);
-                        prefs->setBool("/options/transform/rectcorners", true);
-                        prefs->setBool("/options/transform/pattern",     true);
-                        prefs->setBool("/options/transform/gradient",    true);
-
-                        Inkscape::UI::ShapeEditor::blockSetItem(true);
-                        doc->getRoot()->scaleChildItemsRec(Geom::Scale(1/ratio),Geom::Point(0, 0), false);
-                        Inkscape::UI::ShapeEditor::blockSetItem(false);
-
-                        // Restore preferences
-                        prefs->setBool("/options/transform/stroke",      transform_stroke);
-                        prefs->setBool("/options/transform/rectcorners", transform_rectcorners);
-                        prefs->setBool("/options/transform/pattern",     transform_pattern);
-                        prefs->setBool("/options/transform/gradient",    transform_gradient);
-
-                    } else if (response == 6) {
-
-                        // Save preferences
-                        bool onlysensitive = prefs->getBool("/options/kbselection/onlysensitive",true);
-                        bool onlyvisible   = prefs->getBool("/options/kbselection/onlyvisible",  true);
-
-                        prefs->setBool("/options/kbselection/onlysensitive", false);
-                        prefs->setBool("/options/kbselection/onlyvisible",   false);
-
-                        Inkscape::Selection *selection = desktop->getSelection();
-                        Inkscape::SelectionHelper::selectAllInAll( desktop );
-
-                        double height = root->height.computed;
-                        selection->setScaleRelative( Geom::Point(0,height), Geom::Scale(96.0/90.0,96.0/90.0) );
-                        selection->clear();
-
-                        prefs->setBool("/options/kbselection/onlysensitive", onlysensitive);
-                        prefs->setBool("/options/kbselection/onlyvisible",   onlyvisible  );
-
-                        did_scaling = true;
-
-                    }
-
-                    need_fix_box3d = false; // setScaleRelative() handles box3d
-                    need_fix_guides = true; // Always fix guides
-                }
-
-                else if (need_fix_units) {
-                    Glib::ustring msg = _(
-                        "Old Inkscape files use 1in == 90px. CSS requires 1in == 96px.\n"
-                        "Drawings meant to match a physical size (e.g. Letter or A4)\n"
-                        "will be too small. Scaling the drawing can correct for this.\n"
-                        "Internal scaling can be handled either by setting the SVG 'viewBox'\n"
-                        "attribute to compensate or by scaling all objects in the drawing.");
-                    Gtk::Dialog scaleDialog( _("Old Inkscape file detected (90 DPI)"), false);
-
-                    Gtk::Label info;
-                    info.set_markup(msg.c_str());
-                    info.show();
-                    scaleDialog.get_content_area()->pack_start(info, false, false, 20);
-
-                    Gtk::CheckButton backupButton( _("Create backup file (in same directory).") );
-                    bool backup = prefs->getBool("/options/dpifixbackup", true);
-                    backupButton.set_active( backup );
-                    backupButton.show();
-                    scaleDialog.get_content_area()->pack_start(backupButton, false, false, 20);
-
-                    scaleDialog.add_button(_("Set 'viewBox'"),  1);
-                    scaleDialog.add_button(_("Scale elements"), 2);
-                    scaleDialog.add_button(_("Ignore"),         3);
-                    scaleDialog.add_button("Scale test - group",    4);
-                    scaleDialog.add_button("Scale test - children", 5);
-                    scaleDialog.add_button("Scale test - all",      6);
-
-                    gint response = scaleDialog.run();
-                    backup = backupButton.get_active();
-                    prefs->setBool("/options/dpifixbackup", backup);
-
-                    if ( backup && response != 3) {
-                        sp_file_save_backup( uri );
-                    }
-
-                    if (response == 1) {
-
-                        if (!root->viewBox_set) {
-                            doc->setViewBox(Geom::Rect::from_xywh(
-                                                0, 0,
-                                                doc->getWidth().value("px"),
-                                                doc->getHeight().value("px")));
-                            }
-                        Inkscape::Util::Quantity width  =
-                            Inkscape::Util::Quantity(doc->getWidth().value("px")/ratio, "px" );
-                        Inkscape::Util::Quantity height =
-                            Inkscape::Util::Quantity(doc->getHeight().value("px")/ratio,"px" );
-                        doc->setWidthAndHeight( width, height, false );
-
-                        need_fix_guides = true; // Only fix guides if drawing scaled
-                        need_fix_box3d = true;
-
-                    } else if (response == 2) {
-
-                        std::list<Inkscape::Extension::Effect *> effects;
-                        Inkscape::Extension::db.get_effect_list(effects);
-                        std::list<Inkscape::Extension::Effect *>::iterator it = effects.begin();
-                        bool did = false;
-                        while (it != effects.end()){
-                            if (strcmp((*it)->get_id(), "org.inkscape.dpi90to96") == 0) {
-                                Inkscape::UI::View::View *view = desktop;
-                               (*it)->effect(view);
-                               did = true;
-                               break;
-                            }
-                            ++it;
-                        }
-                        if (!did) {
-                            std::cerr << "sp_file_open: Failed to find dpi90to96 extension." << std::endl;
-                        }
-                        need_fix_guides = true; // Only fix guides if drawing scaled
-                        did_scaling = true;
-
-                    } else if (response == 4) {
-
-                        Inkscape::Util::Quantity width  =
-                            Inkscape::Util::Quantity(doc->getWidth().value("px")/ratio, "px" );
-                        Inkscape::Util::Quantity height =
-                            Inkscape::Util::Quantity(doc->getHeight().value("px")/ratio,"px" );
-                        doc->setWidthAndHeight( width, height, false );
-
-                        if (!root->viewBox_set) {
-
-                            // Save preferences
-                            Inkscape::Preferences *prefs = Inkscape::Preferences::get();
-                            bool onlysensitive = prefs->getBool("/options/kbselection/onlysensitive",true);
-                            bool onlyvisible   = prefs->getBool("/options/kbselection/onlyvisible",  true);
-
-                            prefs->setBool("/options/kbselection/onlysensitive", false);
-                            prefs->setBool("/options/kbselection/onlyvisible",   false);
-
-                            Inkscape::Selection *selection = desktop->getSelection();
-                            Inkscape::SelectionHelper::selectAllInAll( desktop );
-                            selection->group();
-                            SPItem * group = selection->singleItem();
-                            if (group) {
-                                group->setAttribute("transform","scale(1.06666667,1.06666667)");
-                            } else {
-                                std::cerr << "sp_file_open: Failed to get group!" << std::endl;
-                            }
-                            selection->clear();
-                            selection->add( group );
-                            selection->ungroup();
-                            selection->clear();
-
-                            prefs->setBool("/options/kbselection/onlysensitive", onlysensitive);
-                            prefs->setBool("/options/kbselection/onlyvisible",   onlyvisible  );
-
-                            did_scaling = true;
-                        }
-
-                        need_fix_box3d = true;
-                        need_fix_guides = true; // Only fix guides if drawing scaled
-
-                    } else if (response == 5) {
-
-                        Inkscape::Util::Quantity width  =
-                            Inkscape::Util::Quantity(doc->getWidth().value("px")/ratio, "px" );
-                        Inkscape::Util::Quantity height =
-                            Inkscape::Util::Quantity(doc->getHeight().value("px")/ratio,"px" );
-                        doc->setWidthAndHeight( width, height, false );
-
-                        if (!root->viewBox_set) {
-
-                            // Save preferences
-                            Inkscape::Preferences *prefs = Inkscape::Preferences::get();
-                            bool transform_stroke      = prefs->getBool("/options/transform/stroke", true);
-                            bool transform_rectcorners = prefs->getBool("/options/transform/rectcorners", true);
-                            bool transform_pattern     = prefs->getBool("/options/transform/pattern", true);
-                            bool transform_gradient    = prefs->getBool("/options/transform/gradient", true);
-
-                            prefs->setBool("/options/transform/stroke",      true);
-                            prefs->setBool("/options/transform/rectcorners", true);
-                            prefs->setBool("/options/transform/pattern",     true);
-                            prefs->setBool("/options/transform/gradient",    true);
-
-                            Inkscape::UI::ShapeEditor::blockSetItem(true);
-                            doc->getRoot()->scaleChildItemsRec(Geom::Scale(1/ratio),Geom::Point(0, 0), false);
-                            Inkscape::UI::ShapeEditor::blockSetItem(false);
-
-                            // Restore preferences
-                            prefs->setBool("/options/transform/stroke",      transform_stroke);
-                            prefs->setBool("/options/transform/rectcorners", transform_rectcorners);
-                            prefs->setBool("/options/transform/pattern",     transform_pattern);
-                            prefs->setBool("/options/transform/gradient",    transform_gradient);
-
-                            did_scaling = true;
-
-                        }
-
-                    } else if (response == 6) {
-
-                        double old_height = root->height.computed;
-                        Inkscape::Util::Quantity width  =
-                            Inkscape::Util::Quantity(doc->getWidth().value("px")/ratio, "px" );
-                        Inkscape::Util::Quantity height =
-                            Inkscape::Util::Quantity(doc->getHeight().value("px")/ratio,"px" );
-                        doc->setWidthAndHeight( width, height, false );
-
-                        if (!root->viewBox_set) {
-
-                            // Save preferences
-                            Inkscape::Preferences *prefs = Inkscape::Preferences::get();
-                            bool onlysensitive = prefs->getBool("/options/kbselection/onlysensitive",true);
-                            bool onlyvisible   = prefs->getBool("/options/kbselection/onlyvisible",  true);
-
-                            prefs->setBool("/options/kbselection/onlysensitive", false);
-                            prefs->setBool("/options/kbselection/onlyvisible",   false);
-
-                            Inkscape::Selection *selection = desktop->getSelection();
-                            Inkscape::SelectionHelper::selectAllInAll( desktop );
-                            double height = root->height.computed;
-
-                            // So far we have just enlarged the drawing but due to the
-                            // inverted coordinate system we must scale around the old
-                            // height position.
-                            selection->setScaleRelative( Geom::Point(0,old_height), Geom::Scale(96.0/90.0,96.0/90.0) );
-                            selection->clear();
-
-                            prefs->setBool("/options/kbselection/onlysensitive", onlysensitive);
-                            prefs->setBool("/options/kbselection/onlyvisible",   onlyvisible  );
-
-                            did_scaling = true;
-                        }
-
-                        need_fix_box3d = false; // setScaleRelative() handls box3s
-                        need_fix_guides = true; // Only fix guides if drawing scaled
-
-                    } else {
-                        // Ignore
-                        need_fix_grid_mm = true;
-                    }
-                }
-
-                // Fix guides and grids and perspective
-                for (SPObject *child = root->firstChild() ; child; child = child->getNext() ) {
-                    SPNamedView *nv = dynamic_cast<SPNamedView *>(child);
-                    if (nv) {
-                        if (need_fix_guides) {
-                            // std::cout << "Fixing guides" << std::endl;
-                            for (SPObject *child2 = nv->firstChild() ; child2; child2 = child2->getNext() ) {
-                                SPGuide *gd = dynamic_cast<SPGuide *>(child2);
-                                if (gd) {
-                                    gd->moveto( gd->getPoint() / ratio, true );
-                                }
-                            }
-                        }
-                    
-                        for(std::vector<Inkscape::CanvasGrid *>::const_iterator it=nv->grids.begin();it!=nv->grids.end();++it ) {
-                            Inkscape::CanvasXYGrid *xy = dynamic_cast<Inkscape::CanvasXYGrid *>(*it);
-                            if (xy) { 
-                                // std::cout << "A grid: " << xy->getSVGName() << std::endl;
-                                // std::cout << "  Origin: " << xy->origin
-                                //           << "  Spacing: " << xy->spacing << std::endl;
-                                // std::cout << (xy->isLegacy()?"  Legacy":"  Not Legacy") << std::endl;
-                                Geom::Scale scale = doc->getDocumentScale();
-                                if (xy->isLegacy()) {
-                                    if (xy->isPixel()) {
-                                        if (need_fix_grid_mm) {
-                                            xy->Scale( Geom::Scale(1,1) ); // See note below
-                                        } else {
-                                            scale *= Geom::Scale(ratio,ratio);
-                                            xy->Scale( scale.inverse() ); /* *** */
-                                        }
-                                    } else {
-                                        if (need_fix_grid_mm) {
-                                            xy->Scale( Geom::Scale(ratio,ratio) );
-                                        } else {
-                                            xy->Scale( scale.inverse() ); /* *** */
-                                        }
-                                    }
-                                } else {
-                                    if (need_fix_guides) {
-                                        if(did_scaling){
-                                            xy->Scale( Geom::Scale(ratio,ratio).inverse() );
-                                        } else {
-                                            // HACK: Scaling the document does not seem to cause
-                                            // grids defined in document units to be updated.
-                                            // This forces an update.
-                                            xy->Scale( Geom::Scale(1,1) );
-                                        }
-                                    }
-                                }
-                            }
-                        }
-                    }  // If SPNamedView
-
-                    SPDefs *defs = dynamic_cast<SPDefs *>(child);
-                    if (defs && need_fix_box3d) {
-                        for (SPObject *child = defs->firstChild() ; child; child = child->getNext() ) {
-                            Persp3D* persp3d = dynamic_cast<Persp3D *>(child);
-                            if (persp3d) {
-                                std::vector<Glib::ustring> tokens;
-
-                                const gchar* vp_x = persp3d->getAttribute("inkscape:vp_x");
-                                const gchar* vp_y = persp3d->getAttribute("inkscape:vp_y");
-                                const gchar* vp_z = persp3d->getAttribute("inkscape:vp_z");
-                                const gchar* vp_o = persp3d->getAttribute("inkscape:persp3d-origin");
-                                // std::cout << "Found Persp3d: "
-                                //           << " vp_x: " << vp_x
-                                //           << " vp_y: " << vp_y
-                                //           << " vp_z: " << vp_z << std::endl;
-                                Proj::Pt2 pt_x (vp_x);
-                                Proj::Pt2 pt_y (vp_y);
-                                Proj::Pt2 pt_z (vp_z);
-                                Proj::Pt2 pt_o (vp_o);
-                                pt_x = pt_x * (1.0/ratio);
-                                pt_y = pt_y * (1.0/ratio);
-                                pt_z = pt_z * (1.0/ratio);
-                                pt_o = pt_o * (1.0/ratio);
-                                persp3d->setAttribute("inkscape:vp_x",pt_x.coord_string());
-                                persp3d->setAttribute("inkscape:vp_y",pt_y.coord_string());
-                                persp3d->setAttribute("inkscape:vp_z",pt_z.coord_string());
-                                persp3d->setAttribute("inkscape:persp3d-origin",pt_o.coord_string());
-                            }
-                        }
-                    }
-                }  // Look for SPNamedView and SPDefs loop
-
-                // desktop->getDocument()->ensureUpToDate();  // Does not update box3d!
-                DocumentUndo::done(desktop->getDocument(), SP_VERB_NONE, _("Update Document"));
-
-            }  // If old Inkscape version
+            if (sp_version_inside_range(root->version.inkscape, 0, 1, 0, 92)) {
+                sp_file_convert_dpi(doc);
+            }
         }  // If use_gui
 
+
         // resize the window to match the document properties
         sp_namedview_window_from_document(desktop);
         sp_namedview_update_layers_from_document(desktop);
diff --git a/src/file.h b/src/file.h
index 2fc4ea910..c6ff61c25 100644
--- a/src/file.h
+++ b/src/file.h
@@ -205,6 +205,9 @@ void sp_file_print (Gtk::Window& parentWindow);
 void sp_file_vacuum (SPDocument *doc);
 void sp_file_convert_text_baseline_spacing(SPDocument *doc);
 void sp_file_convert_font_name(SPDocument *doc);
+void sp_file_convert_dpi(SPDocument *doc);
+enum File_DPI_Fix { FILE_DPI_UNCHANGED = 0, FILE_DPI_VIEWBOX_SCALED, FILE_DPI_DOCUMENT_SCALED };
+extern int sp_file_convert_dpi_method_commandline;
 
 #endif // SEEN_SP_FILE_H
 
diff --git a/src/main.cpp b/src/main.cpp
index 4c63402fb..7a786234e 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -15,6 +15,7 @@
  * ... and various people who have worked with various projects
  *   Jon A. Cruz <jon@oncruz.org>
  *   Abhishek Sharma
+ *   Marc Jeanmougin
  *
  * Copyright (C) 1999-2004 authors
  * Copyright (C) 2001-2002 Ximian, Inc.
@@ -167,6 +168,7 @@ enum {
     SP_ARG_VERSION,
     SP_ARG_VACUUM_DEFS,
     SP_ARG_NO_CONVERT_TEXT_BASELINE_SPACING,
+    SP_ARG_CONVERT_DPI_METHOD,
 #ifdef WITH_DBUS
     SP_ARG_DBUS_LISTEN,
     SP_ARG_DBUS_NAME,
@@ -278,6 +280,7 @@ static void resetCommandlineGlobals() {
         sp_query_id = NULL;
         sp_vacuum_defs = FALSE;
         sp_no_convert_text_baseline_spacing = FALSE;
+        sp_file_convert_dpi_method_commandline = -1;
 #ifdef WITH_DBUS
         sp_dbus_listen = FALSE;
         sp_dbus_name = NULL;
@@ -539,6 +542,11 @@ struct poptOption options[] = {
     N_("Do not fix legacy (pre-0.92) files' text baseline spacing on opening."),
     NULL},
 
+    {"convert-dpi-method", 0,
+    POPT_ARG_STRING, NULL, SP_ARG_CONVERT_DPI_METHOD,
+    N_("Method used to convert pre-.92 document dpi, if needed."),
+    "[none|scale-viewbox|scale-document]"},
+
     POPT_AUTOHELP POPT_TABLEEND
 };
 
@@ -2180,6 +2188,21 @@ sp_process_args(poptContext ctx)
                 }
                 break;
             }
+            case SP_ARG_CONVERT_DPI_METHOD: {
+                gchar const *arg = poptGetOptArg(ctx);
+                if (arg != NULL) {
+                    if (!strcmp(arg,"none")) {
+                        sp_file_convert_dpi_method_commandline = FILE_DPI_UNCHANGED;
+                    } else if (!strcmp(arg,"scale-viewbox")) {
+                        sp_file_convert_dpi_method_commandline = FILE_DPI_VIEWBOX_SCALED;
+                    } else if (!strcmp(arg,"scale-document")) {
+                        sp_file_convert_dpi_method_commandline = FILE_DPI_DOCUMENT_SCALED;
+                    } else {
+                        g_warning("Invalid update option");
+                    }
+                }
+                break;
+            }
             case POPT_ERROR_BADOPT: {
                 g_warning ("Invalid option %s", poptBadOption(ctx, 0));
                 exit(1);