Draft: Disabled automatic DXF library download - fixes #1785

Note for existing users: Can be reenabled in menu Edit > Preferences >
Import-Export > DXF > Automatic update

src/Mod/Draft/Resources/ui/userprefs-import1.ui

@@ -6,8 +6,8 @@
    <rect>
     <x>0</x>
     <y>0</y>
-    <width>521</width>
-    <height>528</height>
+    <width>505</width>
+    <height>543</height>
    </rect>
   </property>
   <property name="windowTitle">
@@ -20,6 +20,35 @@
    <property name="margin">
     <number>9</number>
    </property>
+   <item>
+    <widget class="QGroupBox" name="groupBox_2">
+     <property name="title">
+      <string>Automatic update</string>
+     </property>
+     <layout class="QVBoxLayout" name="verticalLayout_2">
+      <item>
+       <layout class="QHBoxLayout" name="horizontalLayout_9">
+        <item>
+         <widget class="Gui::PrefCheckBox" name="checkBox_3">
+          <property name="toolTip">
+           <string>&lt;html&gt;&lt;head/&gt;&lt;body&gt;&lt;p&gt;By checking this, you will allow FreeCAD to download and update the&lt;/p&gt;&lt;p&gt;components needed for DXF import and export. You can also do that&lt;/p&gt;&lt;p&gt;manually, by visiting https://github.com/yorikvanhavre/Draft-dxf-importer&lt;/p&gt;&lt;/body&gt;&lt;/html&gt;</string>
+          </property>
+          <property name="text">
+           <string>Allow FreeCAD to automatically download and update the DXF libraries</string>
+          </property>
+          <property name="prefEntry" stdset="0">
+           <cstring>dxfAllowDownload</cstring>
+          </property>
+          <property name="prefPath" stdset="0">
+           <cstring>Mod/Draft</cstring>
+          </property>
+         </widget>
+        </item>
+       </layout>
+      </item>
+     </layout>
+    </widget>
+   </item>
    <item>
     <widget class="QGroupBox" name="GroupBox12">
      <property name="title">

src/Mod/Draft/importDXF.py

@@ -69,27 +69,39 @@
         FreeCAD.Console.PrintWarning("DXF libraries need to be updated. Downloading...\n")
         libsok = False
 if not libsok:
-    files = ['dxfColorMap.py','dxfImportObjects.py','dxfLibrary.py','dxfReader.py']
-    baseurl = 'https://raw.githubusercontent.com/yorikvanhavre/Draft-dxf-importer/'+str(CURRENTDXFLIB)+"/"
-    import ArchCommands
-    from FreeCAD import Base
-    progressbar = Base.ProgressIndicator()
-    progressbar.start("Downloading files...",4)
-    for f in files:
-        progressbar.next()
-        p = None
-        p = ArchCommands.download(baseurl+f,force=True)
-        if not p:
-            FreeCAD.Console.PrintWarning("Download of dxf libraries failed. Please download them manually from\nhttps://github.com/yorikvanhavre/Draft-dxf-importer\nand place them in your macros folder\n")
-            break
-    progressbar.stop() 
-
-    sys.path.append(FreeCAD.ConfigGet("UserAppData"))
-    try:
-        import dxfColorMap, dxfLibrary, dxfReader
-    except ImportError:
+    p = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Mod/Draft")
+    dxfAllowDownload = p.GetBool("dxfAllowDownload",False)
+    if dxfAllowDownload:
+        files = ['dxfColorMap.py','dxfImportObjects.py','dxfLibrary.py','dxfReader.py']
+        baseurl = 'https://raw.githubusercontent.com/yorikvanhavre/Draft-dxf-importer/'+str(CURRENTDXFLIB)+"/"
+        import ArchCommands
+        from FreeCAD import Base
+        progressbar = Base.ProgressIndicator()
+        progressbar.start("Downloading files...",4)
+        for f in files:
+            progressbar.next()
+            p = None
+            p = ArchCommands.download(baseurl+f,force=True)
+            if not p:
+                FreeCAD.Console.PrintWarning("Download of dxf libraries failed. Please download them manually from\nhttps://github.com/yorikvanhavre/Draft-dxf-importer\nand place them in your macros folder\n")
+                break
+        progressbar.stop() 
+
+        sys.path.append(FreeCAD.ConfigGet("UserAppData"))
+        try:
+            import dxfColorMap, dxfLibrary, dxfReader
+        except ImportError:
+            dxfReader = None
+            dxfLibrary = None
+    else:
+        FreeCAD.Console.PrintWarning("The DXF import/export libraries needed by FreeCAD to handle the DXF format\n")
+        FreeCAD.Console.PrintWarning("were not found on this system. Please either enable FreeCAD to download these\n")
+        FreeCAD.Console.PrintWarning("libraries (menu Edit > Preferences > Import-Export > DXF > Enable downloads) or download\n")
+        FreeCAD.Console.PrintWarning("these libraries manually, as explained on\n")
+        FreeCAD.Console.PrintWarning("https://github.com/yorikvanhavre/Draft-dxf-importer\n")
         dxfReader = None
         dxfLibrary = None
+
 
 if open.__module__ == '__builtin__':
     pythonopen = open # to distinguish python built-in open function from the one declared here