use ctypes to access the zbar library

gui/qt/main_window.py

@@ -2001,7 +2001,7 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, PrintError):
     def read_tx_from_qrcode(self):
         from electrum import qrscanner
         try:
-            data = qrscanner.scan_qr(self.config)
+            data = qrscanner.scan_barcode(self.config.get_video_device())
         except BaseException as e:
             self.show_error(str(e))
             return
@@ -2517,9 +2517,9 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, PrintError):
         #combo.addItem("Manually specify a device", config.get("video_device"))
         index = qr_combo.findData(self.config.get("video_device"))
         qr_combo.setCurrentIndex(index)
-        msg = _("Install the zbar package to enable this.\nOn linux, type: 'apt-get install python-zbar'")
+        msg = _("Install the zbar package to enable this.")
         qr_label = HelpLabel(_('Video Device') + ':', msg)
-        qr_combo.setEnabled(qrscanner.zbar is not None)
+        qr_combo.setEnabled(qrscanner.libzbar is not None)
         on_video_device = lambda x: self.config.set_key("video_device", str(qr_combo.itemData(x).toString()), True)
         qr_combo.currentIndexChanged.connect(on_video_device)
         gui_widgets.append((qr_label, qr_combo))

gui/qt/qrtextedit.py

@@ -49,12 +49,12 @@ class ScanQRTextEdit(ButtonsTextEdit, MessageBoxMixin):
     def qr_input(self):
         from electrum import qrscanner, get_config
         try:
-            data = qrscanner.scan_qr(get_config())
+            data = qrscanner.scan_barcode(get_config().get_video_device())
         except BaseException as e:
             self.show_error(str(e))
-            return ""
+            data = ''
         if type(data) != str:
-            return
+            data = ''
         self.setText(data)
         return data
 

lib/qrscanner.py

@@ -24,43 +24,42 @@
 # SOFTWARE.
 
 import os
-from i18n import _
+import sys
+from ctypes import cdll, c_char_p
 
-try:
-    import zbar
-except ImportError:
-    zbar = None
-
-proc = None
+if sys.platform == 'darwin':
+    name = 'libzbar.dylib'
+elif sys.platform == 'windows':
+    name = 'libzbar.dll'
+else:
+    name = 'libzbar.so.0'
 
+try:
+    libzbar = cdll.LoadLibrary(name)
+except OSError:
+    libzbar = None
 
-def scan_qr(config):
-    global proc
-    if not zbar:
-        raise RuntimeError("\n".join([_("Cannot start QR scanner."),_("The zbar package is not available."),_("On Linux, try 'sudo pip install zbar'")]))
-    if proc is None:
-        device = config.get("video_device", "default")
-        if device == 'default':
-            device = ''
-        _proc = zbar.Processor()
-        _proc.init(video_device=device)
-        # set global only if init did not raise an exception
-        proc = _proc
 
-
-    proc.visible = True
-    while True:
-        try:
-            proc.process_one()
-        except Exception:
-            # User closed the preview window
-            return ""
-        for r in proc.results:
-            if str(r.type) != 'QRCODE':
-                continue
-            # hiding the preview window stops the camera
-            proc.visible = False
-            return r.data
+def scan_barcode(device='', timeout=-1, display=True, threaded=False):
+    if libzbar is None:
+        raise RuntimeError("Cannot start QR scanner; zbar not available.")
+    libzbar.zbar_symbol_get_data.restype = c_char_p
+    proc = libzbar.zbar_processor_create(threaded)
+    libzbar.zbar_processor_request_size(proc, 640, 480)
+    libzbar.zbar_processor_init(proc, device, display)
+    libzbar.zbar_processor_set_visible(proc)
+    if libzbar.zbar_process_one(proc, timeout):
+        symbols = libzbar.zbar_processor_get_results(proc)
+    else:
+        symbols = None
+    libzbar.zbar_processor_destroy(proc)
+    if symbols is None:
+        return
+    if not libzbar.zbar_symbol_set_get_size(symbols):
+        return
+    symbol = libzbar.zbar_symbol_set_first_symbol(symbols)
+    data = libzbar.zbar_symbol_get_data(symbol)
+    return data
 
 def _find_system_cameras():
     device_root = "/sys/class/video4linux"
@@ -71,3 +70,7 @@ def _find_system_cameras():
             name = name.strip('\n')
             devices[name] = os.path.join("/dev",device)
     return devices
+
+
+if __name__ == "__main__":
+    print(scan_barcode())

lib/simple_config.py

@@ -232,6 +232,13 @@ class SimpleConfig(PrintError):
             fee_rate = self.get('fee_per_kb', self.max_fee_rate()/2)
         return fee_rate
 
+    def get_video_device(self):
+        device = self.get("video_device", "default")
+        if device == 'default':
+            device = ''
+        return device
+
+
 def read_system_config(path=SYSTEM_CONFIG_PATH):
     """Parse and return the system config settings in /etc/electrum.conf."""
     result = {}