qml: handle DataOverflow in qeqr.py and QRImage

electrum/gui/qml/components/controls/QRImage.qml

@@ -1,4 +1,5 @@
 import QtQuick 2.6
+import QtQuick.Controls 2.15
 
 Item {
     id: root
@@ -17,10 +18,10 @@ Item {
     }
 
     Image {
-        source: qrdata && render ? 'image://qrgen/' + qrdata : ''
+        source: qrdata && render && qrprops.modules > 0 ? 'image://qrgen/' + qrdata : ''
 
         Rectangle {
-            visible: root.render
+            visible: root.render && qrprops.valid
             color: 'white'
             x: (parent.width - width) / 2
             y: (parent.height - height) / 2
@@ -28,6 +29,7 @@ Item {
             height: qrprops.icon_modules * qrprops.box_size
 
             Image {
+                visible: qrprops.valid
                 source: '../../../icons/electrum.png'
                 x: 1
                 y: 1
@@ -36,5 +38,10 @@ Item {
                 scale: 0.9
             }
         }
+        Label {
+            visible: !qrprops.valid
+            text: qsTr('Data too big for QR')
+            anchors.centerIn: parent
+        }
     }
 }

electrum/gui/qml/qeqr.py

@@ -1,5 +1,7 @@
 import asyncio
 import qrcode
+from qrcode.exceptions import DataOverflowError
+
 import math
 import urllib
 
@@ -143,6 +145,7 @@ class QEQRImageProvider(QQuickImageProvider):
 
         # calculate best box_size
         pixelsize = min(self._max_size, 400)
+        try:
             modules = 17 + 4 * qr.best_fit() + qr.border * 2
             qr.box_size = math.floor(pixelsize/modules)
 
@@ -150,6 +153,12 @@ class QEQRImageProvider(QQuickImageProvider):
 
             pimg = qr.make_image(fill_color='black', back_color='white')
             self.qimg = ImageQt.ImageQt(pimg)
+        except DataOverflowError:
+            # fake it
+            modules = 17 + qr.border * 2
+            box_size = math.floor(pixelsize/modules)
+            self.qimg = QImage(box_size * modules, box_size * modules, QImage.Format_RGB32)
+            self.qimg.fill(QColor('gray'))
         return self.qimg, self.qimg.size()
 
 # helper for placing icon exactly where it should go on the QR code
@@ -167,12 +176,17 @@ class QEQRImageProviderHelper(QObject):
 
         # calculate best box_size
         pixelsize = min(self._max_size, 400)
+        try:
             modules = 17 + 4 * qr.best_fit() + qr.border * 2
-        qr.box_size = math.floor(pixelsize/modules)
+            valid = True
+        except DataOverflowError:
+            # fake it
+            modules = 17 + qr.border * 2
+            valid = False
 
+        qr.box_size = math.floor(pixelsize/modules)
         # calculate icon width in modules
         icon_modules = int(modules / 5)
         icon_modules += (icon_modules+1)%2 # force odd
 
-        return { 'modules': modules, 'box_size': qr.box_size, 'icon_modules': icon_modules }
+        return { 'modules': modules, 'box_size': qr.box_size, 'icon_modules': icon_modules, 'valid' : valid }
-