docs(example): fetch data from remote url

examples/00_howdoi/data_from_remote_url.py

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+r"""
+Installation requirements:
+    pip install trame trame-vuetify trame-vtk vtk
+"""
+
+import tempfile
+from urllib.error import HTTPError
+from urllib.request import urlretrieve
+
+import vtkmodules.vtkRenderingOpenGL2  # noqa
+from trame.ui.vuetify3 import SinglePageLayout
+from vtkmodules.vtkFiltersGeometry import vtkGeometryFilter
+
+# VTK imports
+from vtkmodules.vtkIOXML import vtkXMLUnstructuredGridReader
+from vtkmodules.vtkRenderingCore import (
+    vtkActor,
+    vtkDataSetMapper,
+    vtkRenderer,
+    vtkRenderWindow,
+)
+
+# Trame imports
+from trame.app import get_server
+from trame.widgets import vtk as vtk_widgets
+from trame.widgets import vuetify3 as vuetify
+
+server = get_server(client_type="vue3")
+server.cli.add_argument(
+    "--remote-url",
+    dest="remote_url",
+    help="Remote URL pointing to a VTU file.",
+    default="https://github.com/Kitware/trame/raw/master/examples/data/disk_out_ref.vtu",
+)
+(args, _unknown) = server.cli.parse_known_args()
+
+state, ctrl = server.state, server.controller
+
+with tempfile.NamedTemporaryFile() as fp:
+    try:
+        print(f"using local file {fp.name}")
+        urlretrieve(args.remote_url, fp.name)
+        reader = vtkXMLUnstructuredGridReader()
+        reader.SetFileName(fp.name)
+        reader.Update()
+    except HTTPError as e:
+        print(RuntimeError(f"Failed to download {args.remote_url}. {e.reason}"))
+        raise e
+
+
+dataset = reader.GetOutput()
+
+renderer = vtkRenderer()
+renderer.SetBackground(1, 1, 1)
+render_window = vtkRenderWindow()
+render_window.AddRenderer(renderer)
+
+surface_filter = vtkGeometryFilter()
+surface_filter.SetInputConnection(reader.GetOutputPort())
+surface_filter.SetPassThroughPointIds(True)
+
+mapper = vtkDataSetMapper()
+mapper.SetInputConnection(surface_filter.GetOutputPort())
+actor = vtkActor()
+actor.GetProperty().SetOpacity(0.5)
+actor.SetMapper(mapper)
+
+renderer.AddActor(actor)
+renderer.ResetCamera()
+
+
+state.trame__title = "Fetch Remote URL example"
+ctrl.on_server_ready.add(ctrl.view_update)
+
+with SinglePageLayout(server) as layout:
+    layout.title.set_text("Unstructured grid from remote URL")
+
+    with layout.content:
+        with vuetify.VContainer(fluid=True, classes="fill-height pa-0 ma-0"):
+            with vuetify.VRow(dense=True, style="height: 100%;"):
+                with vuetify.VCol(
+                    classes="pa-0",
+                    style="border-right: 1px solid #ccc; position: relative;",
+                ):
+                    view = vtk_widgets.VtkLocalView(
+                        render_window,
+                    )
+                    ctrl.view_update = view.update
+
+if __name__ == "__main__":
+    server.start()