Use file from the Binary field to display document

On Windows the file used to create the Evince document must be kept after the
initialization.
Also reusing the file cache mechanism of the Binary field, prevents to create
temporary files on each call of display.
Evince document needs to have the proper extension to be sure to load the
proper backend. So the cache file must be retrieved with the requested
extension.
And finally we use Document.factory_get_document_full so if leading with the
filename extension does not work, it will try to guess from the data.

Closes #13307
(grafted from 34deeaf3c0215f793c3e673de3ee2e04971ebee4)

--HG--
branch : 7.0

tryton/tryton/gui/window/view_form/model/field.py

@@ -9,6 +9,7 @@ import os
 import tempfile
 from decimal import Decimal
 from itertools import chain
+from pathlib import Path
 
 import tryton.common as common
 from tryton.common import (
@@ -1048,26 +1049,56 @@ class ReferenceField(Field):
 
 
 class _FileCache(object):
-    def __init__(self, path):
-        self.path = path
+    def __init__(self, data=None):
+        _, filename = tempfile.mkstemp(prefix='tryton_')
+        self.path = Path(filename)
+        self.suffixes = {}
+        if data:
+            with open(self.path, 'wb') as fp:
+                fp.write(data)
+
+    @property
+    def data(self):
+        with open(self.path, 'rb') as fp:
+            return fp.read()
 
     def __del__(self):
         try:
             os.remove(self.path)
         except IOError:
             pass
+        for path in self.suffixes.values():
+            try:
+                os.remove(path)
+            except IOError:
+                pass
+
+    def with_suffix(self, suffix):
+        if suffix in self.suffixes:
+            return self.suffixes[suffix]
+        _, filename = tempfile.mkstemp(prefix='tryton_', suffix=suffix)
+        self.suffixes[suffix] = path = Path(filename)
+        with open(path, 'wb') as fp:
+            fp.write(self.data)
+        return path
 
 
 class BinaryField(Field):
 
     _default = None
 
+    def _set_file_cache(self, record, data):
+        if isinstance(data, str):
+            data = data.encode('utf-8')
+        file_cache = _FileCache(data)
+        self.set(record, file_cache)
+        return file_cache
+
     def get(self, record):
         result = record.value.get(self.name, self._default)
         if isinstance(result, _FileCache):
             try:
-                with open(result.path, 'rb') as fp:
-                    result = fp.read()
+                result = result.data
             except IOError:
                 result = self.get_data(record)
         return result
@@ -1076,13 +1107,7 @@ class BinaryField(Field):
         return self.get(record)
 
     def set_client(self, record, value, force_change=False):
-        _, filename = tempfile.mkstemp(prefix='tryton_')
-        data = value or b''
-        if isinstance(data, str):
-            data = data.encode('utf-8')
-        with open(filename, 'wb') as fp:
-            fp.write(data)
-        self.set(record, _FileCache(filename))
+        self._set_file_cache(record, value or b'')
         self.sig_changed(record)
         record.validate(softvalidation=True)
         record.set_modified(self.name)
@@ -1106,15 +1131,20 @@ class BinaryField(Field):
                     [record.id], [self.name], context=context)
             except RPCException:
                 return b''
-            _, filename = tempfile.mkstemp(prefix='tryton_')
-            data = values[self.name] or b''
-            if isinstance(data, str):
-                data = data.encode('utf-8')
-            with open(filename, 'wb') as fp:
-                fp.write(data)
-            self.set(record, _FileCache(filename))
+            self._set_file_cache(record, values[self.name] or b'')
         return self.get(record)
 
+    def get_filename(self, record, suffix=None):
+        data = self.get_data(record)
+        file_cache = record.value.get(self.name)
+        if not isinstance(file_cache, _FileCache):
+            file_cache = self._set_file_cache(record, data)
+        if suffix:
+            filename = file_cache.with_suffix(suffix)
+        else:
+            filename = file_cache.path
+        return filename
+
 
 class DictField(Field):
 

tryton/tryton/gui/window/view_form/view/form_gtk/document.py

@@ -1,7 +1,6 @@
 # This file is part of Tryton.  The COPYRIGHT file at the top level of
 # this repository contains the full copyright notices and license terms.
 from pathlib import Path
-from tempfile import NamedTemporaryFile
 
 from gi.repository import Gdk, GLib, Gtk
 
@@ -76,17 +75,17 @@ class Document(BinaryMixin, Widget):
             self.image.hide()
             if self.evince_view:
                 self.evince_scroll.show()
+                suffix = None
                 if self.filename_field:
-                    suffix = self.filename_field.get(self.record)
-                else:
-                    suffix = None
+                    filename = self.filename_field.get(self.record)
+                    if filename:
+                        suffix = Path(filename).suffix
+                filename = Path(self.field.get_filename(self.record, suffix))
                 try:
-                    with NamedTemporaryFile(suffix=suffix) as fp:
-                        fp.write(data)
-                        path = Path(fp.name)
-                        document = (
-                            EvinceDocument.Document.factory_get_document(
-                                path.as_uri()))
+                    document = (
+                        EvinceDocument.Document.factory_get_document_full(
+                            filename.as_uri(),
+                            EvinceDocument.DocumentLoadFlags.NONE))
                     model = EvinceView.DocumentModel()
                     model.set_document(document)
                     self.evince_view.set_model(model)