qt: qrreader: keep both old and new toolchain; try to abstract it away

contrib/build-wine/deterministic.spec

@@ -53,7 +53,7 @@ datas += collect_data_files('bitbox02')
 # We don't put these files in to actually include them in the script but to make the Analysis method scan them for imports
 a = Analysis([home+'run_electrum',
               home+'electrum/gui/qt/main_window.py',
-              home+'electrum/gui/qt/qrreader/camera_dialog.py',
+              home+'electrum/gui/qt/qrreader/qtmultimedia/camera_dialog.py',
               home+'electrum/gui/text.py',
               home+'electrum/util.py',
               home+'electrum/wallet.py',

contrib/make_zbar.sh

@@ -47,45 +47,39 @@ info "Building $pkgname..."
     if ! [ -r config.status ] ; then
         if [ "$BUILD_TYPE" = "wine" ] ; then
             # windows target
-            ./configure \
+            AUTOCONF_FLAGS="$AUTOCONF_FLAGS \
-                $AUTOCONF_FLAGS \
-                --prefix="$here/$pkgname/dist" \
                 --with-x=no \
-                --enable-pthread=no \
-                --enable-doc=no \
                 --enable-video=yes \
-                --with-directshow=yes \
                 --with-jpeg=no \
-                --with-python=no \
+                --with-directshow=yes \
-                --with-gtk=no \
+                --disable-dependency-tracking"
-                --with-qt=no \
+        elif [ $(uname) == "Darwin" ]; then
-                --with-java=no \
+            # macos target
-                --with-imagemagick=no \
+            AUTOCONF_FLAGS="$AUTOCONF_FLAGS \
-                --with-dbus=no \
+                --with-x=no \
-                --enable-codes=qrcode \
+                --enable-video=no \
-                --disable-dependency-tracking \
+                --with-jpeg=no"
-                --disable-static \
-                --enable-shared || fail "Could not configure $pkgname. Please make sure you have a C compiler installed and try again."
         else
             # linux target
-            ./configure \
+            AUTOCONF_FLAGS="$AUTOCONF_FLAGS \
-                $AUTOCONF_FLAGS \
-                --prefix="$here/$pkgname/dist" \
                 --with-x=yes \
-                --enable-pthread=no \
-                --enable-doc=no \
                 --enable-video=yes \
-                --with-jpeg=yes \
+                --with-jpeg=yes"
-                --with-python=no \
-                --with-gtk=no \
-                --with-qt=no \
-                --with-java=no \
-                --with-imagemagick=no \
-                --with-dbus=no \
-                --enable-codes=qrcode \
-                --disable-static \
-                --enable-shared || fail "Could not configure $pkgname. Please make sure you have a C compiler installed and try again."
         fi
+        ./configure \
+            $AUTOCONF_FLAGS \
+            --prefix="$here/$pkgname/dist" \
+            --enable-pthread=no \
+            --enable-doc=no \
+            --with-python=no \
+            --with-gtk=no \
+            --with-qt=no \
+            --with-java=no \
+            --with-imagemagick=no \
+            --with-dbus=no \
+            --enable-codes=qrcode \
+            --disable-static \
+            --enable-shared || fail "Could not configure $pkgname. Please make sure you have a C compiler installed and try again."
     fi
     make -j4 || fail "Could not build $pkgname"
     make install || fail "Could not install $pkgname"

contrib/osx/osx.spec

@@ -96,7 +96,7 @@ binaries += [b for b in collect_dynamic_libs('PyQt5') if 'macstyle' in b[0]]
 # We don't put these files in to actually include them in the script but to make the Analysis method scan them for imports
 a = Analysis([electrum+ MAIN_SCRIPT,
               electrum+'electrum/gui/qt/main_window.py',
-              electrum+'electrum/gui/qt/qrreader/camera_dialog.py',
+              electrum+'electrum/gui/qt/qrreader/qtmultimedia/camera_dialog.py',
               electrum+'electrum/gui/text.py',
               electrum+'electrum/util.py',
               electrum+'electrum/wallet.py',

electrum/gui/qt/__init__.py

@@ -275,28 +275,6 @@ class ElectrumGui(Logger):
             network_updated_signal_obj=self.network_updated_signal_obj)
         self.network_dialog.show()
 
-    @staticmethod
-    def warn_if_cant_import_qrreader(parent, *, show_warning=True) -> bool:
-        """Checks it QR reading from camera is possible.  It can fail on a
-        system lacking QtMultimedia.  This can be removed in the future when
-        we are unlikely to encounter Qt5 installations that are missing
-        QtMultimedia
-        """
-        try:
-            from .qrreader import QrReaderCameraDialog
-        except ImportError as e:
-            if show_warning:
-                icon = QMessageBox.Warning
-                title = _("QR Reader Error")
-                message = _("QR reader failed to load. This may happen if "
-                            "you are using an older version of PyQt5.") + "\n\n" + str(e)
-                if isinstance(parent, MessageBoxMixin):
-                    parent.msg_box(title=title, text=message, icon=icon, parent=None)
-                else:
-                    custom_message_box(title=title, text=message, icon=icon, parent=parent)
-            return True
-        return False
-
     def _create_window_for_wallet(self, wallet):
         w = ElectrumWindow(self, wallet)
         self.windows.append(w)

electrum/gui/qt/main_window.py

@@ -103,6 +103,7 @@ from .channels_list import ChannelsList
 from .confirm_tx_dialog import ConfirmTxDialog
 from .transaction_dialog import PreviewTxDialog
 from .rbf_dialog import BumpFeeDialog, DSCancelDialog
+from .qrreader import scan_qrcode
 
 if TYPE_CHECKING:
     from . import ElectrumGui
@@ -2820,54 +2821,28 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger):
             self.show_error("failed to import backup" + '\n' + str(e))
             return
 
-    # Due to the asynchronous nature of the qr reader we need to keep the
-    # dialog instance as member variable to prevent reentrancy/multiple ones
-    # from being presented at once.
-    _qr_dialog = None
-
     def read_tx_from_qrcode(self):
-        if self._qr_dialog:
+        def cb(success: bool, error: str, data):
-            self.logger.warning("QR dialog is already presented, ignoring.")
+            if not success:
-            return
+                if error:
-        if self.gui_object.warn_if_cant_import_qrreader(self):
+                    self.show_error(error)
-            return
+                return
-        from .qrreader import QrReaderCameraDialog, CameraError, MissingQrDetectionLib
+            if not data:
-        self._qr_dialog = None
+                return
-        try:
+            # if the user scanned a bitcoin URI
-            self._qr_dialog = QrReaderCameraDialog(parent=self.top_level_window(), config=self.config)
+            if data.lower().startswith(BITCOIN_BIP21_URI_SCHEME + ':'):
-
+                self.pay_to_URI(data)
-            def _on_qr_reader_finished(success: bool, error: str, data):
+                return
-                if self._qr_dialog:
+            if data.lower().startswith('channel_backup:'):
-                    self._qr_dialog.deleteLater()
+                self.import_channel_backup(data)
-                    self._qr_dialog = None
+                return
-                if not success:
+            # else if the user scanned an offline signed tx
-                    if error:
+            tx = self.tx_from_text(data)
-                        self.show_error(error)
+            if not tx:
-                    return
+                return
-                if not data:
+            self.show_transaction(tx)
-                    return
-                # if the user scanned a bitcoin URI
-                if data.lower().startswith(BITCOIN_BIP21_URI_SCHEME + ':'):
-                    self.pay_to_URI(data)
-                    return
-                if data.lower().startswith('channel_backup:'):
-                    self.import_channel_backup(data)
-                    return
-                # else if the user scanned an offline signed tx
-                tx = self.tx_from_text(data)
-                if not tx:
-                    return
-                self.show_transaction(tx)
 
-            self._qr_dialog.qr_finished.connect(_on_qr_reader_finished)
+        scan_qrcode(parent=self.top_level_window(), config=self.config, callback=cb)
-            self._qr_dialog.start_scan(self.config.get_video_device())
-        except (MissingQrDetectionLib, CameraError) as e:
-            self._qr_dialog = None
-            self.show_error(str(e))
-        except Exception as e:
-            self.logger.exception('camera error')
-            self._qr_dialog = None
-            self.show_error(repr(e))
 
     def read_tx_from_file(self) -> Optional[Transaction]:
         fileName = getOpenFileName(

electrum/gui/qt/qrreader/__init__.py

@@ -1,30 +1,141 @@
-#!/usr/bin/env python3
+# Copyright (C) 2021 The Electrum developers
+# Distributed under the MIT software license, see the accompanying
+# file LICENCE or http://www.opensource.org/licenses/mit-license.php
 #
-# Electron Cash - lightweight Bitcoin client
+# We have two toolchains to scan qr codes:
-# Copyright (C) 2019 Axel Gembe <derago@gmail.com>
+# 1. access camera via QtMultimedia, take picture, feed picture to zbar
+# 2. let zbar handle whole flow (including accessing the camera)
 #
-# Permission is hereby granted, free of charge, to any person
+# notes:
-# obtaining a copy of this software and associated documentation files
+# - zbar needs to be compiled with platform-dependent extra config options to be able
-# (the "Software"), to deal in the Software without restriction,
+#   to access the camera
-# including without limitation the rights to use, copy, modify, merge,
+# - zbar fails to access the camera on macOS
-# publish, distribute, sublicense, and/or sell copies of the Software,
+# - qtmultimedia seems to support more cameras on Windows than zbar
-# and to permit persons to whom the Software is furnished to do so,
+# - qtmultimedia is often not packaged with PyQt5
-# subject to the following conditions:
+#   in particular, on debian, you need both "python3-pyqt5" and "python3-pyqt5.qtmultimedia"
+# - older versions of qtmultimedia don't seem to work reliably
 #
-# The above copyright notice and this permission notice shall be
+# Considering the above, we use QtMultimedia for Windows and macOS, as there
-# included in all copies or substantial portions of the Software.
+# most users run our binaries where we can make sure the packaged versions work well.
+# On Linux where many people run from source, we use zbar.
 #
-# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+# Note: this module is safe to import on all platforms.
-# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+
-# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+import sys
-# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+from typing import Callable, Optional, TYPE_CHECKING, Mapping
-# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+
-# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+from PyQt5.QtWidgets import QMessageBox, QWidget
-# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+
-# SOFTWARE.
+from electrum.i18n import _
-
+from electrum.util import UserFacingException
-from .camera_dialog import (QrReaderCameraDialog, CameraError, NoCamerasFound,
+from electrum.logging import get_logger
-                            NoCameraResolutionsFound, MissingQrDetectionLib)
+
-from .validator import (QrReaderValidatorResult, AbstractQrReaderValidator,
+from electrum.gui.qt.util import MessageBoxMixin, custom_message_box
-                        QrReaderValidatorCounting, QrReaderValidatorColorizing,
+
-                        QrReaderValidatorStrong, QrReaderValidatorCounted)
+
+if TYPE_CHECKING:
+    from electrum.simple_config import SimpleConfig
+
+
+_logger = get_logger(__name__)
+
+
+def scan_qrcode(
+        *,
+        parent: Optional[QWidget],
+        config: 'SimpleConfig',
+        callback: Callable[[bool, str, Optional[str]], None],
+) -> None:
+    if sys.platform == 'darwin' or sys.platform in ('windows', 'win32'):
+        _scan_qrcode_using_qtmultimedia(parent=parent, config=config, callback=callback)
+    else:  # desktop Linux and similar
+        _scan_qrcode_using_zbar(parent=parent, config=config, callback=callback)
+
+
+def find_system_cameras() -> Mapping[str, str]:
+    """Returns a camera_description -> camera_path map."""
+    if sys.platform == 'darwin' or sys.platform in ('windows', 'win32'):
+        try:
+            from .qtmultimedia import find_system_cameras
+        except ImportError as e:
+            return {}
+        else:
+            return find_system_cameras()
+    else:  # desktop Linux and similar
+        from electrum import qrscanner
+        return qrscanner.find_system_cameras()
+
+
+# --- Internals below (not part of external API)
+
+def _scan_qrcode_using_zbar(
+        *,
+        parent: Optional[QWidget],
+        config: 'SimpleConfig',
+        callback: Callable[[bool, str, Optional[str]], None],
+) -> None:
+    from electrum import qrscanner
+    data = None
+    try:
+        data = qrscanner.scan_barcode(config.get_video_device())
+    except UserFacingException as e:
+        success = False
+        error = str(e)
+    except BaseException as e:
+        _logger.exception('camera error')
+        success = False
+        error = repr(e)
+    else:
+        success = True
+        error = ""
+    callback(success, error, data)
+
+
+# Use a global to prevent multiple QR dialogs created simultaneously
+_qr_dialog = None
+
+
+def _scan_qrcode_using_qtmultimedia(
+        *,
+        parent: Optional[QWidget],
+        config: 'SimpleConfig',
+        callback: Callable[[bool, str, Optional[str]], None],
+) -> None:
+    try:
+        from .qtmultimedia import QrReaderCameraDialog, CameraError, MissingQrDetectionLib
+    except ImportError as e:
+        icon = QMessageBox.Warning
+        title = _("QR Reader Error")
+        message = _("QR reader failed to load. This may happen if "
+                    "you are using an older version of PyQt5.") + "\n\n" + str(e)
+        if isinstance(parent, MessageBoxMixin):
+            parent.msg_box(title=title, text=message, icon=icon, parent=None)
+        else:
+            custom_message_box(title=title, text=message, icon=icon, parent=parent)
+        return
+
+    global _qr_dialog
+    if _qr_dialog:
+        _logger.warning("QR dialog is already presented, ignoring.")
+        return
+    _qr_dialog = None
+    try:
+        _qr_dialog = QrReaderCameraDialog(parent=parent, config=config)
+
+        def _on_qr_reader_finished(success: bool, error: str, data):
+            global _qr_dialog
+            if _qr_dialog:
+                _qr_dialog.deleteLater()
+                _qr_dialog = None
+            callback(success, error, data)
+
+        _qr_dialog.qr_finished.connect(_on_qr_reader_finished)
+        _qr_dialog.start_scan(config.get_video_device())
+    except (MissingQrDetectionLib, CameraError) as e:
+        _qr_dialog = None
+        callback(False, str(e), None)
+    except Exception as e:
+        _logger.exception('camera error')
+        _qr_dialog = None
+        callback(False, repr(e), None)
+

electrum/gui/qt/qrreader/qtmultimedia/__init__.py

@@ -0,0 +1,39 @@
+#!/usr/bin/env python3
+#
+# Electron Cash - lightweight Bitcoin client
+# Copyright (C) 2019 Axel Gembe <derago@gmail.com>
+#
+# Permission is hereby granted, free of charge, to any person
+# obtaining a copy of this software and associated documentation files
+# (the "Software"), to deal in the Software without restriction,
+# including without limitation the rights to use, copy, modify, merge,
+# publish, distribute, sublicense, and/or sell copies of the Software,
+# and to permit persons to whom the Software is furnished to do so,
+# subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be
+# included in all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+from typing import Mapping
+
+from .camera_dialog import (QrReaderCameraDialog, CameraError, NoCamerasFound,
+                            NoCameraResolutionsFound, MissingQrDetectionLib)
+from .validator import (QrReaderValidatorResult, AbstractQrReaderValidator,
+                        QrReaderValidatorCounting, QrReaderValidatorColorizing,
+                        QrReaderValidatorStrong, QrReaderValidatorCounted)
+
+
+def find_system_cameras() -> Mapping[str, str]:
+    """Returns a camera_description -> camera_path map."""
+    from PyQt5.QtMultimedia import QCameraInfo
+    system_cameras = QCameraInfo.availableCameras()
+    return {cam.description(): cam.deviceName() for cam in system_cameras}

electrum/gui/qt/qrreader/qtmultimedia/camera_dialog.py

@@ -39,12 +39,14 @@ from electrum.i18n import _
 from electrum.qrreader import get_qr_reader, QrCodeResult
 from electrum.logging import Logger
 
+from electrum.gui.qt.util import MessageBoxMixin, FixedAspectRatioLayout, ImageGraphicsEffect
+
 from .video_widget import QrReaderVideoWidget
 from .video_overlay import QrReaderVideoOverlay
 from .video_surface import QrReaderVideoSurface
 from .crop_blur_effect import QrReaderCropBlurEffect
 from .validator import AbstractQrReaderValidator, QrReaderValidatorCounted, QrReaderValidatorResult
-from ..util import MessageBoxMixin, FixedAspectRatioLayout, ImageGraphicsEffect
+
 
 class CameraError(RuntimeError):
     ''' Base class of the camera-related error conditions. '''

electrum/gui/qt/qrtextedit.py

@@ -7,6 +7,7 @@ from electrum.util import UserFacingException
 from electrum.logging import Logger
 
 from .util import ButtonsTextEdit, MessageBoxMixin, ColorScheme, getOpenFileName
+from .qrreader import scan_qrcode
 
 
 class ShowQRTextEdit(ButtonsTextEdit):
@@ -72,49 +73,23 @@ class ScanQRTextEdit(ButtonsTextEdit, MessageBoxMixin, Logger):
         else:
             self.setText(data)
 
-    # Due to the asynchronous nature of the qr reader we need to keep the
-    # dialog instance as member variable to prevent reentrancy/multiple ones
-    # from being presented at once.
-    qr_dialog = None
-
     def qr_input(self, *, callback=None) -> None:
-        if self.qr_dialog:
+        def cb(success: bool, error: str, data):
-            self.logger.warning("QR dialog is already presented, ignoring.")
+            if not success:
-            return
+                if error:
-        from . import ElectrumGui
+                    self.show_error(error)
-        if ElectrumGui.warn_if_cant_import_qrreader(self):
+                return
-            return
+            if not data:
-        from .qrreader import QrReaderCameraDialog, CameraError, MissingQrDetectionLib
+                data = ''
-        try:
+            if self.allow_multi:
-            self.qr_dialog = QrReaderCameraDialog(parent=self.top_level_window(), config=self.config)
+                new_text = self.text() + data + '\n'
-
+            else:
-            def _on_qr_reader_finished(success: bool, error: str, data):
+                new_text = data
-                if self.qr_dialog:
+            self.setText(new_text)
-                    self.qr_dialog.deleteLater()
+            if callback and success:
-                    self.qr_dialog = None
+                callback(data)
-                if not success:
+
-                    if error:
+        scan_qrcode(parent=self.top_level_window(), config=self.config, callback=cb)
-                        self.show_error(error)
-                    return
-                if not data:
-                    data = ''
-                if self.allow_multi:
-                    new_text = self.text() + data + '\n'
-                else:
-                    new_text = data
-                self.setText(new_text)
-                if callback and success:
-                    callback(data)
-
-            self.qr_dialog.qr_finished.connect(_on_qr_reader_finished)
-            self.qr_dialog.start_scan(self.config.get_video_device())
-        except (MissingQrDetectionLib, CameraError) as e:
-            self.qr_dialog = None
-            self.show_error(str(e))
-        except Exception as e:
-            self.logger.exception('camera error')
-            self.qr_dialog = None
-            self.show_error(repr(e))
 
     def contextMenuEvent(self, e):
         m = self.createStandardContextMenu()

electrum/gui/qt/settings_dialog.py

@@ -220,18 +220,10 @@ class SettingsDialog(WindowModalDialog):
         msg = (_("For scanning QR codes.") + "\n"
                + _("Install the zbar package to enable this."))
         qr_label = HelpLabel(_('Video Device') + ':', msg)
-        system_cameras = []
+        from .qrreader import find_system_cameras
-        try:
+        system_cameras = find_system_cameras()
-            from PyQt5.QtMultimedia import QCameraInfo
+        for cam_desc, cam_path in system_cameras.items():
-            system_cameras = QCameraInfo.availableCameras()
+            qr_combo.addItem(cam_desc, cam_path)
-        except ImportError as e:
-            # Older Qt or missing libs -- disable GUI control and inform user why
-            qr_combo.setEnabled(False)
-            qr_label.setEnabled(False)
-            qr_combo.setToolTip(_("Unable to probe for cameras on this system. QtMultimedia is likely missing."))
-            qr_label.setToolTip(qr_combo.toolTip())
-        for cam in system_cameras:
-            qr_combo.addItem(cam.description(), cam.deviceName())
         index = qr_combo.findData(self.config.get("video_device"))
         qr_combo.setCurrentIndex(index)
         on_video_device = lambda x: self.config.set_key("video_device", qr_combo.itemData(x), True)

electrum/qrscanner.py

@@ -26,7 +26,7 @@
 import os
 import sys
 import ctypes
-from typing import Optional
+from typing import Optional, Mapping
 
 from .util import UserFacingException
 from .i18n import _
@@ -82,7 +82,7 @@ def scan_barcode(device='', timeout=-1, display=True, threaded=False) -> Optiona
     return data.decode('utf8')
 
 
-def _find_system_cameras():
+def find_system_cameras() -> Mapping[str, str]:
     device_root = "/sys/class/video4linux"
     devices = {} # Name -> device
     if os.path.exists(device_root):

setup.py

@@ -76,6 +76,7 @@ setup(
         'electrum.gui',
         'electrum.gui.qt',
         'electrum.gui.qt.qrreader',
+        'electrum.gui.qt.qrreader.qtmultimedia',
         'electrum.plugins',
     ] + [('electrum.plugins.'+pkg) for pkg in find_packages('electrum/plugins')],
     package_dir={