ReferenceImageLayer: Add new layer class.

New class `ReferenceImageLayer` added, which refers
a picture file in another location of local filesystem.
Mypaint monitors that file and follows its update.
It is just referred, cannot be modified from mypaint.
ORA file records only its filename and position.

It would be useful when that picture is generated by
another (and processor consuming) program,  such as
blender.

Also, under certain case, LayerPropertiesUI class
shows GTK-warning or causing Segfault.
This bug fixed.

Also, now Vectorlayer can have `blueprint`
as current layer image.
To use this feature, invoke `New Vector layer from current` action
from menu.

gui/document.py

@@ -1412,6 +1412,9 @@ def new_layer_cb(self, action):
             layer_kwds["y"] = y
             layer_kwds["w"] = w
             layer_kwds["h"] = h
+            if "Current" in action.get_name():
+                layer_kwds["source-layer"] = layers.current
+
         elif "Group" in action.get_name():
             layer_class = lib.layer.LayerStack
 
@@ -1424,23 +1427,6 @@ def new_layer_cb(self, action):
             path = layers.path_below(path, insert=True)
         assert path is not None
 
-        if "Import" in action.get_name():
-            app = self.app
-            try:
-                dlg = app.filehandler.get_open_dialog(
-                        file_filters=app.filehandler.file_filters)
-                preview = Gtk.Image()
-                dlg.set_preview_widget(preview)
-                dlg.connect("update-preview", 
-                        app.filehandler.update_preview_cb, preview)
-
-                if dlg.run() == Gtk.ResponseType.OK:
-                    layer_kwds["import-filename"] = dlg.get_filename().decode('utf-8')
-                else:
-                    return
-            finally:
-                dlg.destroy()
-
         self.model.add_layer(path, layer_class=layer_class, **layer_kwds)
 
         self.layerblink_state.activate(action)

gui/filehandling.py

@@ -859,6 +859,16 @@ def import_layers(self, filenames):
             return
         logger.info('Imported layers from %r', filenames)
 
+    # XXX for `reference layer`
+    def add_reference_layers(self, filenames):
+        """Load a file, replacing the current working document."""
+
+        if not self._call_doc_load_method(self.doc.model.add_reference_layers,
+                                          filenames, True):
+            return
+        logger.info('Add reference layers from %r', filenames)
+    # XXX for `reference layer` end
+
     def _call_doc_load_method(self, method, arg, is_import):
         """Internal: common GUI aspects of loading or importing files.
 
@@ -1129,11 +1139,21 @@ def open_scratchpad_dialog(self):
 
     def import_layers_cb(self, action):
         """Action callback: import layers from multiple files."""
-        dialog = Gtk.FileChooserDialog(
+        # XXX for `reference layer`
+        if "Import" in action.get_name():
             title = C_(
                 u'Layers→Import Layers: files-chooser dialog: title',
                 u"Import Layers",
-            ),
+            )
+        else:
+            title = C_(
+                u'Layers→Add Reference Layer: files-chooser dialog: title',
+                u"Add Reference Layer",
+            )
+
+
+        dialog = Gtk.FileChooserDialog(
+            title = title,
             parent = self.app.drawWindow,
             action = Gtk.FileChooserAction.OPEN,
             buttons = [
@@ -1152,15 +1172,17 @@ def import_layers_cb(self, action):
 
         _add_filters_to_dialog(self.file_filters, dialog)
 
-        # Choose the most recent save folder.
-        self._update_recent_items()
-        for item in reversed(self._recent_items):
-            uri = item.get_uri()
-            fn, _h = lib.glib.filename_from_uri(uri)
-            dn = os.path.dirname(fn)
-            if os.path.isdir(dn):
-                dialog.set_current_folder(dn)
-                break
+        # XXX for `reference layer`
+        if "Import" in action.get_name():
+            # Choose the most recent save folder.
+            self._update_recent_items()
+            for item in reversed(self._recent_items):
+                uri = item.get_uri()
+                fn, _h = lib.glib.filename_from_uri(uri)
+                dn = os.path.dirname(fn)
+                if os.path.isdir(dn):
+                    dialog.set_current_folder(dn)
+                    break
 
         filenames = []
         try:
@@ -1172,7 +1194,10 @@ def import_layers_cb(self, action):
 
         if filenames:
             filenames = [filename_to_unicode(f) for f in filenames]
-            self.import_layers(filenames)
+            if "Import" in action.get_name():
+                self.import_layers(filenames)
+            else:
+                self.add_reference_layers(filenames)
 
     def save_cb(self, action):
         if not self.filename:

gui/layerprops.glade

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<!-- Generated with glade 3.18.3 -->
+<!-- Generated with glade 3.22.1 -->
 <interface domain="mypaint">
   <requires lib="gtk+" version="3.12"/>
   <object class="GtkAdjustment" id="layer-opacity-adjustment">
@@ -244,6 +244,28 @@ With marking layer(s),you can do some actions which uses other layer(s) as sourc
             <property name="top_attach">3</property>
           </packing>
         </child>
+        <child>
+          <object class="GtkLabel" id="layer-source-label">
+            <property name="can_focus">False</property>
+            <property name="label" translatable="yes">Source</property>
+          </object>
+          <packing>
+            <property name="left_attach">0</property>
+            <property name="top_attach">4</property>
+          </packing>
+        </child>
+        <child>
+          <object class="GtkFileChooserButton" id="layer-source-chooser">
+            <property name="can_focus">False</property>
+            <property name="create_folders">False</property>
+            <property name="title" translatable="yes"/>
+            <signal name="file-set" handler="_v_layer_source_changed_cb" swapped="no"/>
+          </object>
+          <packing>
+            <property name="left_attach">1</property>
+            <property name="top_attach">4</property>
+          </packing>
+        </child>
       </object>
       <packing>
         <property name="left_attach">1</property>

gui/layerprops.py

@@ -24,6 +24,7 @@
 import lib.xml
 from lib.gettext import C_
 import gui.mvp
+import lib.layer # XXX for `reference-layer`
 
 import cairo
 from gi.repository import Gtk
@@ -115,17 +116,25 @@ def __init__(self, docmodel):
         root.layer_thumbnail_updated += self._m_layer_thumbnail_updated_cb
         self._store = None
 
+        # XXX To detect whether this view is active(i.e. shown as dialog)
+        # or not.
+        self.attached = False  
+
     def init_view(self):
         """Set initial state of the view objects."""
-
         # 3-column mode liststore (id, name, sensitive)
-        store = Gtk.ListStore(int, str, bool)
-        modes = STACK_MODES + STANDARD_MODES
-        for mode in modes:
-            label, desc = MODE_STRINGS.get(mode)
-            store.append([mode, label, True])
-        self._store = store
-        self.view.layer_mode_combo.set_model(store)
+        if self._store is None:
+            store = Gtk.ListStore(int, str, bool)
+            modes = STACK_MODES + STANDARD_MODES
+            for mode in modes:
+                label, desc = MODE_STRINGS.get(mode)
+                store.append([mode, label, True])
+            self._store = store
+            self.view.layer_mode_combo.set_model(store)
+        else:
+            self.view.layer_mode_combo.set_model(self._store)
+
+        self.attached = True
 
         # The eye button is greyed out while the view is locked.
         lvm = self._docmodel.layer_view_manager
@@ -143,6 +152,15 @@ def widget(self):
 
     @property
     def _layer(self):
+        # XXX Workaround: To avoid GTK-warning and 
+        # Segfault(abort) Mypaint. 
+        # Once Layer-property dialog is destroied,
+        # the event handler still active, and it causes
+        # some problems around dialog widgets.
+        # So add `attached` attribute and use this to
+        # identify the dialog is exist.
+        if not self.attached:
+            return None
         root = self._docmodel.layer_stack
         return root.current
 
@@ -192,13 +210,16 @@ def _m_current_view_changed_cb(self, lvm):
         self._m2v_layerview_locked()
 
     def _m2v_all(self):
+        if not self._layer:
+            return
         self._m2v_preview()
         self._m2v_name()
         self._m2v_mode()
         self._m2v_opacity()
         for info in self._BOOL_PROPERTIES:
             self._m2v_layer_flag(info)
         self._m2v_layerview_locked()
+        self._m2v_refsource() # XXX for `reference_layer`
 
     def _m2v_preview(self):
         layer = self._layer
@@ -246,13 +267,15 @@ def _m2v_mode(self):
         combo.set_active_iter(active_iter)
 
     def _m2v_opacity(self):
+        layer = self._layer
+        if not layer:
+            return
+
         adj = self.view.layer_opacity_adjustment
         scale = self.view.layer_opacity_scale
-        layer = self._layer
 
         opacity_is_adjustable = not (
-            layer is None
-            or layer is self._docmodel.layer_stack
+            layer is self._docmodel.layer_stack
             or layer.mode == PASS_THROUGH_MODE
         )
         scale.set_sensitive(opacity_is_adjustable)
@@ -264,6 +287,9 @@ def _m2v_opacity(self):
 
     def _m2v_layer_flag(self, info):
         layer = self._layer
+        if not layer:
+            return
+
         propval = getattr(layer, info.property)
         propval_idx = int(propval)
 
@@ -281,6 +307,22 @@ def _m2v_layerview_locked(self):
         btn = self.view.layer_hidden_togglebutton
         btn.set_sensitive(sensitive)
 
+    # XXX for `reference-layer`
+    def _m2v_refsource(self):
+        layer = self._layer
+        show_flag = isinstance(layer, lib.layer.ReferenceImageLayer)
+        refsource_label = self.view.layer_source_label
+        refsource_chooser = self.view.layer_source_chooser
+        if show_flag:
+            refsource_label.show()
+            refsource_chooser.show()
+            assert hasattr(layer, 'reference_path')
+            refsource_chooser.set_filename(layer.reference_path)
+        else:
+            refsource_label.hide()
+            refsource_chooser.hide()
+    # XXX for `reference-layer` end
+
     # View monitoring and response (callback names defined in .glade XML):
 
     def _v_layer_mode_combo_query_tooltip_cb(self, combo, x, y, kbd, tooltip):
@@ -350,6 +392,15 @@ def _v_layer_marked_togglebutton_toggled_cb(self, btn):
                 if (i.property == "marked")][0]
         self._v2m_layer_flag(info)
     # XXX 'marked' layer flag end
+
+    # XXX for `reference_layer`
+    @gui.mvp.model_updater
+    def _v_layer_source_changed_cb(self, btn):
+        cl = self._layer
+        if not cl or not isinstance(cl, lib.layer.ReferenceImageLayer):
+            return
+        cl.set_reference_path(btn.get_filename())
+    # XXX for `reference_layer` end
 
     def _v2m_layer_flag(self, info):
         layer = self._layer
@@ -420,7 +471,13 @@ def __init__(self, parent, docmodel):
         self._ui = LayerPropertiesUI(docmodel)
         self.vbox.pack_start(self._ui.widget, True, True, 0)
         self.set_default_response(Gtk.ResponseType.OK)
+        self.connect("destroy", self.destroy_cb) # XXX workaround for GTK segfault
 
+    def destroy_cb(self, widget):
+        """Destroy handler, to notify LayerPropertiesUI that
+        the parent dialog is already destroyed.
+        """
+        self._ui.attached = False
 
 # Helpers:
 

gui/layerswindow.xml

@@ -13,7 +13,9 @@
     <placeholder name="BasicListActions">
       <menuitem action='NewPaintingLayerAbove'/>
       <menuitem action='NewVectorLayerAbove'/>
+      <menuitem action='NewVectorLayerCurrent'/>
       <menuitem action='NewLayerGroupAbove'/>
+      <menuitem action='NewReferenceLayerAbove'/>
       <separator/>
       <menuitem action='DuplicateLayer'/>
       <menuitem action='RemoveLayer'/>

gui/menu.xml

@@ -248,10 +248,13 @@
       <menuitem action='NewPaintingLayerAbove'/>
       <menuitem action='NewLayerGroupAbove'/>
       <menuitem action='NewVectorLayerAbove'/>
+      <menuitem action='NewVectorLayerCurrent'/>
+      <menuitem action='NewReferenceLayerAbove'/>
       <menu action="LayerNewBelowMenu">
         <menuitem action='NewPaintingLayerBelow'/>
         <menuitem action='NewLayerGroupBelow'/>
         <menuitem action='NewVectorLayerBelow'/>
+        <menuitem action='NewReferenceLayerBelow'/>
       </menu>
       <!-- Current layer: editing: Clipboard -->
       <separator/>

gui/resources.xml

@@ -575,6 +575,32 @@ Vocabulary
           <signal name="activate" handler="new_layer_cb"/>
         </object>
       </child>
+      <!-- XXX for vectorlayer from current -->
+      <child>
+        <object class="GtkAction" id="NewVectorLayerCurrent">
+          <property name="icon-name">mypaint-layer-vector-symbolic</property>
+          <property name="label" translatable="yes" context="Menu→Layer (labels), Accel Editor (labels)">New Vector Layer from current…</property>
+          <property name="tooltip" translatable="yes" context="Accel Editor (descriptions)">Add a new vector layer above the current layer which based on currently selected layer, and begin editing it.</property>
+          <signal name="activate" handler="new_layer_cb"/>
+        </object>
+      </child>
+      <!-- XXX for vectorlayer from current end -->
+      <!-- XXX for `reference layer` -->
+      <child>
+        <object class="GtkAction" id="NewReferenceLayerAbove">
+          <property name="label" translatable="yes" context="Menu→Layer (labels), Accel Editor (labels)">New Reference Layer…</property>
+          <property name="tooltip" translatable="yes" context="Accel Editor (descriptions)">Add a new reference image layer above the current layer. That layer only shows a image file of another location, cannot edit it.</property>
+          <signal name="activate" handler="import_layers_cb"/>
+        </object>
+      </child>
+      <child>
+        <object class="GtkAction" id="NewReferenceLayerBelow">
+          <property name="label" translatable="yes" context="Menu→Layer (labels), Accel Editor (labels)">New Reference Layer Below</property>
+          <property name="tooltip" translatable="yes" context="Accel Editor (descriptions)">Add a new reference image layer below the current layer. That layer only shows a image file of another location, cannot edit it.</property>
+          <signal name="activate" handler="import_layers_cb"/>
+        </object>
+      </child>
+      <!-- XXX for `reference layer` end -->
       <child>
         <object class="GtkAction" id="NewLayerGroupAbove">
           <property name="icon-name">mypaint-layer-group-new-symbolic</property>