Add audio modem integration for transaction sending & receiving

http://www.flaticon.com/free-icon/speaker-outline_54951

Speaker icon made by <a href="http://catalinfertu.com" title="Catalin
Fertu">Catalin Fertu</a> from <a href="http://www.flaticon.com"
title="Flaticon">www.flaticon.com</a> is licensed under <a
href="http://creativecommons.org/licenses/by/3.0/" title="Creative
Commons BY 3.0">CC BY 3.0</a>

http://www.flaticon.com/free-icon/mic_10032

Microphone icon made by <a href="http://www.elegantthemes.com"
title="Elegant Themes">Elegant Themes</a> from <a
href="http://www.flaticon.com" title="Flaticon">www.flaticon.com</a> is
licensed under <a href="http://creativecommons.org/licenses/by/3.0/"
title="Creative Commons BY 3.0">CC BY 3.0</a>

gui/qt/qrtextedit.py

@@ -1,4 +1,5 @@
 from electrum.i18n import _
+from electrum.plugins import run_hook
 from PyQt4.QtGui import *
 from PyQt4.QtCore import *
 
@@ -25,6 +26,7 @@ class ShowQRTextEdit(QRTextEdit):
         super(ShowQRTextEdit, self).__init__(text)
         self.setReadOnly(1)
         self.button.clicked.connect(self.qr_show)
+        run_hook('show_text_edit', self)
 
     def qr_show(self):
         from qrcodewidget import QRDialog
@@ -49,6 +51,7 @@ class ScanQRTextEdit(QRTextEdit):
         if win:
             assert hasattr(win,"config"), "You must pass a window with access to the config to ScanQRTextEdit constructor."
         self.button.clicked.connect(self.qr_input)
+        run_hook('scan_text_edit', self)
 
 
     def qr_input(self):

icons.qrc

@@ -28,6 +28,8 @@
     <file>icons/network.png</file>
     <file>icons/dark_background.png</file>
     <file>icons/qrcode.png</file>
+    <file>icons/microphone.png</file>
+    <file>icons/speaker.png</file>
     <file>icons/trustedcoin.png</file>
   </qresource>
 </RCC>

plugins/audio_modem.py

@@ -0,0 +1,123 @@
+from electrum.plugins import BasePlugin, hook
+from electrum_gui.qt.util import WaitingDialog
+from electrum.util import print_msg
+
+from PyQt4.QtGui import *
+from PyQt4.QtCore import *
+
+import subprocess
+import traceback
+import zlib
+import json
+
+try:
+    subprocess.check_call(['amodem-cli', '--help'])
+    print_msg('Audio MODEM is enabled.')
+    amodem_available = True
+except subprocess.CalledProcessError:
+    print_msg('Audio MODEM is not found.')
+    amodem_available = False
+
+
+def send(parent, blob):
+    print_msg('Sending:', repr(blob))
+    blob = zlib.compress(blob)
+    def sender_thread():
+        try:
+            args = ['amodem-cli', 'send', '-vv']
+            p = subprocess.Popen(args, stdin=subprocess.PIPE)
+            p.stdin.write(blob)
+            p.stdin.close()
+            p.wait()
+        except Exception:
+            traceback.print_exc()
+            p.kill()
+
+    return WaitingDialog(
+        parent=parent, message='Sending transaction to Audio MODEM...',
+        run_task=sender_thread)
+
+
+def recv(parent):
+    def receiver_thread():
+        import subprocess
+        try:
+            args = ['amodem-cli', 'recv', '-vv']
+            p = subprocess.Popen(args, stdout=subprocess.PIPE)
+            return p.stdout.read()
+        except Exception:
+            traceback.print_exc()
+            p.kill()
+
+    def on_success(blob):
+        blob = zlib.decompress(blob)
+        print_msg('Received:', repr(blob))
+        parent.setText(blob)
+
+    return WaitingDialog(
+        parent=parent, message='Receiving transaction from Audio MODEM...',
+        run_task=receiver_thread, on_success=on_success)
+
+
+class Plugin(BasePlugin):
+
+    def fullname(self):
+        return 'Audio MODEM'
+
+    def description(self):
+        return ('Provides support for air-gapped transaction signing.\n\n'
+                'Requires http://github.com/romanz/amodem/')
+
+    def is_available(self):
+        return amodem_available
+
+    is_enabled = is_available
+
+    @hook
+    def transaction_dialog(self, dialog):
+        b = QPushButton()
+        b.setIcon(QIcon(":icons/speaker.png"))
+
+        def handler():
+            blob = json.dumps(dialog.tx.as_dict())
+            self.sender = send(parent=dialog, blob=blob)
+            self.sender.start()
+        b.clicked.connect(handler)
+        dialog.buttons.insertWidget(1, b)
+
+    @hook
+    def scan_text_edit(self, parent):
+        def handler():
+            self.receiver = recv(parent=parent)
+            self.receiver.start()
+        button = add_button(parent=parent, icon_name=':icons/microphone.png')
+        button.clicked.connect(handler)
+
+    @hook
+    def show_text_edit(self, parent):
+        def handler():
+            blob = str(parent.toPlainText())
+            self.sender = send(parent=parent, blob=blob)
+            self.sender.start()
+        button = add_button(parent=parent, icon_name=':icons/speaker.png')
+        button.clicked.connect(handler)
+
+
+def add_button(parent, icon_name):
+    audio_button = QToolButton(parent)
+    audio_button.setIcon(QIcon(icon_name))
+    audio_button.setStyleSheet("QToolButton { border: none; padding: 0px; }")
+    audio_button.setVisible(True)
+
+    parent_resizeEvent = parent.resizeEvent
+
+    def resizeEvent(e):
+        result = parent_resizeEvent(e)
+        qr_button = parent.button
+        left = qr_button.geometry().left() - audio_button.sizeHint().width()
+        top = qr_button.geometry().top()
+        audio_button.move(left, top)
+        return result
+
+    parent.resizeEvent = resizeEvent
+    return audio_button