move qrscanner from plugins to lib

lib/qrscanner.py

@@ -0,0 +1,38 @@
+import os
+
+try:
+    import zbar
+except ImportError:
+    zbar = None
+
+
+def scan_qr(config):
+    if not zbar:
+        return
+    device = config.get("video_device", "default")
+    if device == 'default':
+        device = ''
+    proc = zbar.Processor()
+    proc.init(video_device=device)
+    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
+            return r.data
+        
+
+def _find_system_cameras():
+    device_root = "/sys/class/video4linux"
+    devices = {} # Name -> device
+    if os.path.exists(device_root):
+        for device in os.listdir(device_root):
+            name = open(os.path.join(device_root, device, 'name')).read()
+            name = name.strip('\n')
+            devices[name] = os.path.join("/dev",device)
+    return devices