dbus: return the drawings as array of timestamps

As we're planning to cache the data locally, the timestamps are a
unique-enough way that makes it possible to access a specific drawing.
And this way we can also delete some drawings without all other indices
shifting around.

Fixes #16

README.md

@@ -137,9 +137,9 @@ org.freedesktop.tuhi1.Device
       The physical dimensions (width, height) in µm
       Read-only
 
-  Property: DrawingsAvailable (u)
-      An integer indicating the number of drawings available. Drawings are
-      zero-indexed, see GetJSONData().
+  Property: DrawingsAvailable (at)
+      An array of timestamps of the available drawings. The timestamp of
+      each drawing can be used as index to GetJSONData().
       Read-only
 
   Property: Listening (b)
@@ -202,7 +202,7 @@ org.freedesktop.tuhi1.Device
       signal arriving, the property DrawingsAvailable may still be updated
       and it's the responsibility of the client to fetch the JSON data.
 
-  Method: GetJSONData(index: u) -> (s)
+  Method: GetJSONData(index: t) -> (s)
       Returns a JSON file with the drawings specified by the index argument.
       Drawings are zero-indexed and the requested index must be less than
       the DrawingsAvailable property value. See section JSON FILE FORMAT for

tools/tuhi-kete.py

@@ -325,8 +325,8 @@ class Listener(GObject.Object):
         if self.device is None:
             return
 
-        if self.device.drawings_available > 0:
-            logger.info('{}: drawings available: {}'.format(self.device, self.device.drawings_available))
+        if self.device.drawings_available:
+            self._log_drawings_available(self.device)
 
         if self.device.listening:
             logger.info("{}: device already listening".format(self.device))
@@ -352,7 +352,11 @@ class Listener(GObject.Object):
         self.manager.quit()
 
     def _on_drawings_available(self, device, pspec):
-        logger.info('{}: drawings available: {}'.format(device, device.drawings_available))
+        self._log_drawings_available(device)
+
+    def _log_drawings_available(self, device):
+        s = ", ".join(["{}".format(t) for t in device.drawings_available])
+        logger.info('{}: drawings available: {}'.format(device, s))
 
 
 class Fetcher(GObject.Object):
@@ -371,17 +375,17 @@ class Fetcher(GObject.Object):
             logger.error("{}: device not found".format(address))
             return
 
-        ndrawings = self.device.drawings_available
         if index != 'all':
             try:
-                self.indices = [int(index)]
-                if index >= ndrawings:
+                index = int(index)
+                if index not in self.device.drawings_available:
                     raise ValueError()
+                self.indices = [index]
             except ValueError:
                 logger.error("Invalid index {}".format(index))
                 return
         else:
-            self.indices = list(range(ndrawings))
+            self.indices = self.device.drawings_available
 
     def run(self):
         if self.device is None or self.indices is None:

tuhi/dbusserver.py

@@ -53,7 +53,7 @@ INTROSPECTION_XML = """
     <property type='b' name='Listening' access='read'>
       <annotation name='org.freedesktop.DBus.Property.EmitsChangedSignal' value='true'/>
     </property>
-    <property type='u' name='DrawingsAvailable' access='read'>
+    <property type='at' name='DrawingsAvailable' access='read'>
       <annotation name='org.freedesktop.DBus.Property.EmitsChangedSignal' value='true'/>
     </property>
 
@@ -141,7 +141,7 @@ class TuhiDBusDevice(_TuhiDBus):
         self.name = device.name
         self.btaddr = device.address
         self.width, self.height = 0, 0
-        self.drawings = []
+        self.drawings = {}
         self.paired = device.paired
         self._listening = False
         self._listening_client = None
@@ -215,7 +215,10 @@ class TuhiDBusDevice(_TuhiDBus):
             h = GLib.Variant.new_uint32(self.height)
             return GLib.Variant.new_tuple(w, h)
         elif propname == 'DrawingsAvailable':
-            return GLib.Variant.new_uint32(len(self.drawings))
+            ts = GLib.Variant.new_array(GLib.VariantType('t'),
+                                        [GLib.Variant.new_uint64(t)
+                                            for t in self.drawings.keys()])
+            return ts
         elif propname == 'Listening':
             return GLib.Variant.new_boolean(self.listening)
 
@@ -291,15 +294,17 @@ class TuhiDBusDevice(_TuhiDBus):
         index = args[0]
         try:
             drawing = self.drawings[index]
-        except IndexError:
+        except KeyError:
             return ''
         else:
             return drawing.to_json()
 
     def add_drawing(self, drawing):
-        self.drawings.append(drawing)
-        self.properties_changed({'DrawingsAvailable':
-                                 GLib.Variant.new_uint32(len(self.drawings))})
+        self.drawings[drawing.timestamp] = drawing
+        ts = GLib.Variant.new_array(GLib.VariantType('t'),
+                                    [GLib.Variant.new_uint64(t)
+                                        for t in self.drawings.keys()])
+        self.properties_changed({'DrawingsAvailable': ts})
 
     def notify_button_press_required(self):
         logger.debug("Sending ButtonPressRequired signal")