base: add an argument to peek at the first drawing only

Use --peek to download the first (oldest) drawing on the device but do not
delete it. This is primarily intended as a debugging option, so we can debug
the tablet handling without having to draw new drawings (which cause the
protocol messages to change slightly).

Since the tablet only has a "download oldest file" command this isn't very
useful to end users. If there are two or more files on the tablet, we can only
ever retrieve the oldest one.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>

tuhi/base.py

@@ -450,9 +450,14 @@ def main(args=sys.argv):
                         help='Base directory for configuration',
                         type=str,
                         default=DEFAULT_CONFIG_PATH)
+    parser.add_argument('--peek',
+                        help='Download first drawing only but do not remove it from the device',
+                        action='store_true',
+                        default=False)
 
     ns = parser.parse_args(args[1:])
     TuhiConfig.set_base_path(ns.config_dir)
+    TuhiConfig().peek_at_drawing = ns.peek
     setup_logging(ns.config_dir)
 
     if ns.verbose:

tuhi/config.py

@@ -41,6 +41,7 @@ class TuhiConfig(GObject.Object):
 
             self._devices = {}
             self._scan_config_dir()
+            self.peek_at_drawing = False
         return cls._instance
 
     @GObject.Property

tuhi/gui/application.py

@@ -46,6 +46,12 @@ class Application(Gtk.Application):
                              GLib.OptionFlags.NONE,
                              GLib.OptionArg.NONE,
                              'enable verbose output')
+        # unused, just here to have option compatibility with the tuhi
+        # server but we could add some GUI feedback here
+        self.add_main_option('peek', 0,
+                             GLib.OptionFlags.NONE,
+                             GLib.OptionArg.NONE,
+                             'download first drawing only but do not remove it from the device')
         self._tuhi = None
 
     def do_startup(self):

tuhi/wacom.py

@@ -26,6 +26,7 @@ from .uhid import UHIDDevice
 import tuhi.protocol
 from tuhi.protocol import NordicData, Interactions, Mode, ProtocolVersion, StrokeFile
 from .util import list2hex, flatten
+from tuhi.config import TuhiConfig
 
 logger = logging.getLogger('tuhi.wacom')
 
@@ -745,7 +746,8 @@ class WacomProtocolBase(WacomProtocolLowLevelComm):
     def read_offline_data(self):
         self.set_paper_mode()
         transaction_count = 0
-        while self.count_available_files():
+        file_count = self.count_available_files()
+        while file_count > 0:
             count, timestamp = self.get_stroke_data()
             logger.info(f'receiving {count} bytes drawn on UTC {time.strftime("%y%m%d%H%M%S", time.gmtime(timestamp))}')
             self.start_downloading_oldest_file()
@@ -755,6 +757,12 @@ class WacomProtocolBase(WacomProtocolLowLevelComm):
             drawing = self.parse_pen_data(pen_data, timestamp)
             if drawing:
                 self.emit('drawing', drawing)
+            file_count -= 1
+            if TuhiConfig().peek_at_drawing:
+                logger.info(f'Not deleting drawing from device')
+                if file_count > 0:
+                    logger.info(f'{file_count} more files on device but I can only download the oldest one')
+                break
             self.delete_oldest_file()
             transaction_count += 1
         return transaction_count