ChangeSheetTitleBlock operator

Added operator to change title block of currently selected sheet, it's located right after "Add sheet" button.
The way it works - you select the sheet, select the desired titleblock from dropdown menu and it overrides current titleblock from the sheet with the new one.

src/blenderbim/blenderbim/bim/module/drawing/__init__.py

@@ -55,6 +55,7 @@ classes = (
     operator.LoadSheets,
     operator.OpenSchedule,
     operator.OpenSheet,
+    operator.ChangeSheetTitleBlock,
     operator.OpenView,
     operator.RemoveDrawing,
     operator.RemoveDrawingFromSheet,

src/blenderbim/blenderbim/bim/module/drawing/operator.py

@@ -847,6 +847,27 @@ class CreateSheets(bpy.types.Operator):
         return {"FINISHED"}
 
 
+class ChangeSheetTitleBlock(bpy.types.Operator):
+    bl_idname = "bim.change_sheet_title_block"
+    bl_label = "Change Sheet Title Block"
+    bl_description = "Change the title block of the active sheet"
+    bl_options = {"REGISTER"}
+
+    def execute(self, context):
+        scene = context.scene
+        props = scene.DocProperties
+        active_sheet = props.sheets[props.active_sheet_index]
+        sheet = tool.Ifc.get().by_id(active_sheet.ifc_definition_id)
+
+        sheet_builder = sheeter.SheetBuilder()
+        sheet_builder.data_dir = scene.BIMProperties.data_dir
+        titleblock = scene.DocProperties.titleblock
+        sheet_builder.change_titleblock(sheet, titleblock)
+
+        self.report({"INFO"}, 'Title block changed for sheet "{}" to {}'.format(sheet.Name, titleblock))
+        return {"FINISHED"}
+
+
 class OpenView(bpy.types.Operator):
     bl_idname = "bim.open_view"
     bl_label = "Open View"

src/blenderbim/blenderbim/bim/module/drawing/sheeter.py

@@ -48,7 +48,7 @@ class SheetBuilder:
         view = ET.SubElement(root, "g")
         view.attrib["data-type"] = "titleblock"
         titleblock = ET.SubElement(view, "image")
-        titleblock.attrib["xlink:href"] = "../templates/titleblocks/" + titleblock_name + ".svg"
+        titleblock.attrib["xlink:href"] = f"../templates/titleblocks/{titleblock_name}.svg"
         titleblock.attrib["x"] = "0"
         titleblock.attrib["y"] = "0"
         titleblock.attrib["width"] = str(view_width)
@@ -314,6 +314,33 @@ class SheetBuilder:
             group.append(child)
         return group
 
+    def change_titleblock(self, sheet, titleblock_name):
+        ET.register_namespace("", "http://www.w3.org/2000/svg")
+        ET.register_namespace("xlink", "http://www.w3.org/1999/xlink")
+
+        titleblock_svg_path = os.path.join(self.data_dir, "templates", "titleblocks", f"{titleblock_name}.svg")
+        view_root = ET.parse(titleblock_svg_path).getroot()
+        view_width = self.convert_to_mm(view_root.attrib.get("width"))
+        view_height = self.convert_to_mm(view_root.attrib.get("height"))
+
+        sheet_dir = os.path.join(self.data_dir, "sheets")
+        sheet_name = os.path.splitext(os.path.basename(tool.Drawing.get_document_uri(sheet)))[0]
+        sheet_path = os.path.join(sheet_dir, sheet_name + ".svg")
+        sheet_tree = ET.parse(sheet_path)
+        root = sheet_tree.getroot()
+
+        titleblock = sheet_tree.findall('{http://www.w3.org/2000/svg}g[@data-type="titleblock"]')[0]
+        image = titleblock.findall("{http://www.w3.org/2000/svg}image[@{http://www.w3.org/1999/xlink}href]")[0]
+        image.attrib["{http://www.w3.org/1999/xlink}href"] = f"../templates/titleblocks/{titleblock_name}.svg"
+        image.attrib["width"] = str(view_width)
+        image.attrib["height"] = str(view_height)
+
+        root.attrib["width"] = "{}mm".format(view_width)
+        root.attrib["height"] = "{}mm".format(view_height)
+        root.attrib["viewBox"] = "0 0 {} {}".format(view_width, view_height)
+
+        sheet_tree.write(sheet_path)
+
     def convert_to_mm(self, value):
         # CSS is what defines these possibilities
         # https://www.w3.org/TR/SVG/refs.html#ref-css-values-3

src/blenderbim/blenderbim/bim/module/drawing/ui.py

@@ -274,6 +274,7 @@ class BIM_PT_sheets(Panel):
         row = self.layout.row(align=True)
         row.prop(self.props, "titleblock", text="")
         row.operator("bim.add_sheet", text="", icon="ADD")
+        row.operator("bim.change_sheet_title_block", text="", icon="MODIFIER_DATA")
         row.operator("bim.disable_editing_sheets", text="", icon="CANCEL")
 
         if self.props.sheets and self.props.active_sheet_index < len(self.props.sheets):