Add default filename for exports

When exporting a single file, the filename defaults to the current FCStd
name plus a dash and the name of the object. If multiple objects are
selected, the default is the basename of the FCStd file. No extension is
added. This behavior is controllable via two hidden preferences,
BaseApp/Preferences/General/ExportDefaultFilenameSingle
BaseApp/Preferences/General/ExportDefaultFilenameMultiple

_Allow regeneration of default on new exports_

If an export has been done and it used the default filename, on the next
export regenerate the filename (potentially updating the selected object
name in that filename) instead of just defaulting to the last name.

_Search for extension in chosen filter first_

Originally the file dialog simply searched for the first available extension
in the overall filter list. This commit modifies it to first check the
selected extension, and only if that is empty to search the full filter
list. This section of code only runs if a default filename is set but
does not have an extension ("suffix" in Qt's terms).

src/Gui/CommandDoc.cpp

@@ -25,6 +25,7 @@
 #ifndef _PreComp_
 # include <QApplication>
 # include <QClipboard>
+# include <QDateTime>
 # include <QEventLoop>
 # include <QFileDialog>
 # include <QLabel>
@@ -279,44 +280,221 @@ StdCmdExport::StdCmdExport()
     eType         = 0;
 }
 
+/**
+Create a default filename from a user-specified format string
+ 
+Format options are:
+%F - the basename of the .FCStd file (or the label, if it is not saved yet)
+%Lx - the label of the selected object(s), separated by character 'x'
+%Px - the label of the selected object(s) and their first parent, separated by character 'x'
+%U - the date and time, in UTC, ISO 8601
+%D - the date and time, in local timezone, ISO 8601
+Any other characters are treated literally, though if the filename is illegal
+it will be changed on saving.
+*/
+QString createDefaultExportBasename()
+{
+    QString defaultFilename;
+
+    auto selection = Gui::Selection().getObjectsOfType(App::DocumentObject::getClassTypeId());
+    QString exportFormatString;
+    if (selection.size() == 1) {
+        exportFormatString = QString::fromStdString (App::GetApplication().GetParameterGroupByPath("User parameter:BaseApp/Preferences/General")->
+            GetASCII("ExportDefaultFilenameSingle", "%F-%P-"));
+    } 
+    else {
+        exportFormatString = QString::fromStdString (App::GetApplication().GetParameterGroupByPath("User parameter:BaseApp/Preferences/General")->
+            GetASCII("ExportDefaultFilenameMultiple", "%F"));
+    }
+
+    // For code simplicity, pull all values we might need
+
+    // %F - the basename of the.FCStd file(or the label, if it is not saved yet)
+    QString docFilename = QString::fromUtf8(App::GetApplication().getActiveDocument()->getFileName());
+    QFileInfo fi(docFilename);
+    QString fcstdBasename = fi.completeBaseName();
+    if (fcstdBasename.isEmpty()) {
+        fcstdBasename = QString::fromStdString(App::GetApplication().getActiveDocument()->Label.getStrValue());
+    }
+
+    // %L - the label of the selected object(s)
+    QStringList objectLabels;
+    for (const auto& object : selection) {
+        objectLabels.push_back(QString::fromStdString(object->Label.getStrValue()));
+    }
+
+    // %P - the label of the selected objects and their first parent
+    QStringList parentLabels;
+    for (const auto& object : selection) {
+        auto parents = object->getParents();
+        QString firstParent;
+        if (!parents.empty())
+            firstParent = QString::fromStdString(parents.front().first->Label.getStrValue());
+        parentLabels.append(firstParent + QString::fromStdString(object->Label.getStrValue()));
+    }
+
+    // %U - the date and time, in UTC, ISO 8601
+    QDateTime utc = QDateTime(QDateTime::currentDateTimeUtc());
+    QString utcISO8601 = utc.toString(Qt::ISODate);
+
+    // %D - the date and time, in local timezone, ISO 8601
+    QDateTime local = utc.toLocalTime();
+    QString localISO8601 = local.toString(Qt::ISODate);
+
+    for (int i = 0; i < exportFormatString.size(); ++i) {
+        auto c = exportFormatString.at(i);
+        if (c != QLatin1Char('%')) {
+            defaultFilename.append(c);
+        }
+        else {
+            if (i < exportFormatString.size() - 1) {
+                ++i;
+                auto formatChar = exportFormatString.at(i);
+                QChar separatorChar = QLatin1Char('-');
+                if (formatChar == QLatin1Char('L') ||
+                    formatChar == QLatin1Char('P')) {
+                    if (i < exportFormatString.size() - 1) {
+                        ++i;
+                        separatorChar = exportFormatString.at(i);
+                    }
+                }
+
+                // Handle our format characters:
+                if (formatChar == QLatin1Char('F')) {
+                    defaultFilename.append(fcstdBasename);
+                }
+                else if (formatChar == QLatin1Char('L')) {
+                    defaultFilename.append(objectLabels.join(separatorChar));
+                }
+                else if (formatChar == QLatin1Char('P')) {
+                    defaultFilename.append(parentLabels.join(separatorChar));
+                }
+                else if (formatChar == QLatin1Char('U')) {
+                    defaultFilename.append(utcISO8601);
+                }
+                else if (formatChar == QLatin1Char('D')) {
+                    defaultFilename.append(localISO8601);
+                }
+                else {
+                    FC_WARN("When parsing default export filename format string, %" 
+                        << QString(formatChar).toStdString() 
+                        << " is not a known format string.");
+                }
+            }
+        }
+    }
+
+    // Finally, clean the string:
+    QString invalidCharacters = QLatin1String("/\\?%*:|\"<>");
+    for (const auto &c : invalidCharacters)
+        defaultFilename.replace(c,QLatin1String("_"));
+
+    return defaultFilename;
+}
+
 void StdCmdExport::activated(int iMsg)
 {
     Q_UNUSED(iMsg);
 
-    if (Gui::Selection().countObjectsOfType(App::DocumentObject::getClassTypeId()) == 0) {
+    static QString lastExportFullPath = QString();
+    static bool lastExportUsedGeneratedFilename = true;
+    static QString lastExportFilterUsed = QString();
+
+    auto selection = Gui::Selection().getObjectsOfType(App::DocumentObject::getClassTypeId());
+    if (selection.size() == 0) {
         QMessageBox::warning(Gui::getMainWindow(),
             QString::fromUtf8(QT_TR_NOOP("No selection")),
-            QString::fromUtf8(QT_TR_NOOP("Please select first the objects you want to export.")));
+            QString::fromUtf8(QT_TR_NOOP("Select the objects to export before choosing Export.")));
         return;
     }
 
-    // fill the list of registered endings
+    // fill the list of registered suffixes
     QStringList filterList;
-    std::map<std::string, std::string> FilterList = App::GetApplication().getExportFilters();
-    std::map<std::string, std::string>::const_iterator jt;
-    for (jt=FilterList.begin();jt != FilterList.end();++jt) {
+    std::map<std::string, std::string> filterMap = App::GetApplication().getExportFilters();
+    for (const auto &filter : filterMap) {
         // ignore the project file format
-        if (jt->first.find("(*.FCStd)") == std::string::npos) {
-            filterList << QString::fromLatin1(jt->first.c_str());
+        if (filter.first.find("(*.FCStd)") == std::string::npos) {
+            filterList << QString::fromStdString(filter.first);
         }
     }
-
     QString formatList = filterList.join(QLatin1String(";;"));
-    Base::Reference<ParameterGrp> hPath = App::GetApplication().GetUserParameter().GetGroup("BaseApp")
-                               ->GetGroup("Preferences")->GetGroup("General");
+    Base::Reference<ParameterGrp> hPath = 
+        App::GetApplication().GetUserParameter().GetGroup("BaseApp")->GetGroup("Preferences")->GetGroup("General");
     QString selectedFilter = QString::fromStdString(hPath->GetASCII("FileExportFilter"));
+    if (!lastExportFilterUsed.isEmpty()) {
+        selectedFilter = lastExportFilterUsed;
+    }
 
+    // Create a default filename for the export
+    // * If this is the first export this session default, generate a new default.
+    // * If this is a repeated export during the same session:
+    //     * If the user accepted the default filename last time, regenerate a new
+    //       default, potentially updating the object label.
+    //     * If not, default to their previously-set export filename.
+    QString defaultFilename = lastExportFullPath;
+
+    bool filenameWasGenerated = false;
+    // We want to generate a new default name in two cases:
+    if (defaultFilename.isEmpty() || lastExportUsedGeneratedFilename) {
+        // First, get the name and path of the current .FCStd file, if there is one:
+        QString docFilename = QString::fromUtf8(
+            App::GetApplication().getActiveDocument()->getFileName());
+
+        // Find the default location for our exported file. Three possibilities:
+        QString defaultExportPath;
+        if (!lastExportFullPath.isEmpty()) {
+            QFileInfo fi(lastExportFullPath);
+            defaultExportPath = fi.path();
+        }
+        else if (!docFilename.isEmpty()) {
+            QFileInfo fi(docFilename);
+            defaultExportPath = fi.path();
+        }
+        else {
+            defaultExportPath = Gui::FileDialog::getWorkingDirectory();
+        }
+
+        if (lastExportUsedGeneratedFilename /*<- static, true on first call*/ ) {
+            defaultFilename = defaultExportPath + QLatin1Char('/') + createDefaultExportBasename();
+
+            // Append the last extension used, if there is one.
+            if (!lastExportFullPath.isEmpty()) {
+                QFileInfo lastExportFile(lastExportFullPath);
+                if (!lastExportFile.suffix().isEmpty()) {
+                    defaultFilename += QLatin1String(".") + lastExportFile.suffix();
+                }
+            }
+            filenameWasGenerated = true;
+        }
+    }
+
+    // Launch the file selection modal dialog
     QString fileName = FileDialog::getSaveFileName(getMainWindow(),
-        QObject::tr("Export file"), QString(), formatList, &selectedFilter);
+        QObject::tr("Export file"), defaultFilename, formatList, &selectedFilter);
     if (!fileName.isEmpty()) {
         hPath->SetASCII("FileExportFilter", selectedFilter.toLatin1().constData());
+        lastExportFilterUsed = selectedFilter; // So we can select the same one next time
         SelectModule::Dict dict = SelectModule::exportHandler(fileName, selectedFilter);
         // export the files with the associated modules
         for (SelectModule::Dict::iterator it = dict.begin(); it != dict.end(); ++it) {
             getGuiApplication()->exportTo(it.key().toUtf8(),
                 getActiveGuiDocument()->getDocument()->getName(),
                 it.value().toLatin1());
         }
+
+        // Keep a record of if the user used our suggested generated filename. If they
+        // did, next time we can recreate it, which will update the object label if
+        // there is one.
+        QFileInfo defaultExportFI(defaultFilename);
+        QFileInfo thisExportFI(fileName);
+        if (filenameWasGenerated && 
+            thisExportFI.completeBaseName() == defaultExportFI.completeBaseName()) {
+            lastExportUsedGeneratedFilename = true;
+        }
+        else {
+            lastExportUsedGeneratedFilename = false;
+        }
+        lastExportFullPath = fileName;
     }
 }
 

src/Gui/FileDialog.cpp

@@ -145,13 +145,21 @@ QString FileDialog::getSaveFileName (QWidget * parent, const QString & caption,
             dirName += fi.fileName();
         }
 
-        // get the suffix for the filter
+        // get the suffix for the filter: use the selected filter if there is one,
+        // otherwise find the first valid suffix in the complete list of filters
+        const QString *filterToSearch;
+        if (selectedFilter != nullptr) {
+            filterToSearch = selectedFilter;
+        }
+        else {
+            filterToSearch = &filter;
+        }
         QRegExp rx;
         rx.setPattern(QLatin1String("\\s(\\(\\*\\.\\w{1,})\\W"));
-        int index = rx.indexIn(filter);
+        int index = rx.indexIn(*filterToSearch);
         if (index != -1) {
             // get the suffix with the leading dot
-            QString suffix = filter.mid(index+3, rx.matchedLength()-4);
+            QString suffix = filterToSearch->mid(index+3, rx.matchedLength()-4);
             if (fi.suffix().isEmpty())
                 dirName += suffix;
         }
@@ -199,6 +207,7 @@ QString FileDialog::getSaveFileName (QWidget * parent, const QString & caption,
         dlg.setFileMode(QFileDialog::AnyFile);
         dlg.setAcceptMode(QFileDialog::AcceptSave);
         dlg.setDirectory(dirName);
+        dlg.selectFile(dirName);
         dlg.setOptions(options);
         dlg.setNameFilters(filter.split(QLatin1String(";;")));
         if (selectedFilter && !selectedFilter->isEmpty())