E-book viewer: Fix "View Image" right click menu action not available for svg files included via <img> tags. Fixes #1657717 [Private bug](https://bugs.launchpad.net/calibre/+bug/1657717)

src/calibre/gui2/viewer/documentview.py

@@ -25,7 +25,7 @@ from calibre.gui2.viewer.keys import SHORTCUTS
 from calibre.gui2.viewer.javascript import JavaScriptLoader
 from calibre.gui2.viewer.position import PagePosition
 from calibre.gui2.viewer.config import config, ConfigDialog, load_themes
-from calibre.gui2.viewer.image_popup import ImagePopup
+from calibre.gui2.viewer.image_popup import ImagePopup, render_svg
 from calibre.gui2.viewer.table_popup import TablePopup
 from calibre.gui2.viewer.inspector import WebInspector
 from calibre.gui2.viewer.gestures import GestureHandler
@@ -729,6 +729,11 @@ class DocumentView(QWebView):  # {{{
         elem = r.element()
         if elem.isNull():
             elem = r.enclosingBlockElement()
+        if img.isNull() and elem.tagName().lower() == 'img':
+            # QtWebKit return null pixmaps for svg images
+            iqurl = r.imageUrl()
+            path = self.path(iqurl)
+            img = render_svg(self, path)
         table = None
         parent = elem
         while not parent.isNull():

src/calibre/gui2/viewer/image_popup.py

@@ -9,9 +9,27 @@ __docformat__ = 'restructuredtext en'
 
 from PyQt5.Qt import (QDialog, QPixmap, QUrl, QScrollArea, QLabel, QSizePolicy,
         QDialogButtonBox, QVBoxLayout, QPalette, QApplication, QSize, QIcon,
-        Qt, QTransform)
+        Qt, QTransform, QSvgRenderer, QImage, QPainter)
 
-from calibre.gui2 import choose_save_file, gprefs, NO_URL_FORMATTING
+from calibre.gui2 import choose_save_file, gprefs, NO_URL_FORMATTING, max_available_height
+
+
+def render_svg(widget, path):
+    img = QPixmap()
+    rend = QSvgRenderer()
+    if rend.load(path):
+        dpr = getattr(widget, 'devicePixelRatioF', widget.devicePixelRatio)()
+        sz = rend.defaultSize()
+        h = (max_available_height() - 50)
+        w = int(h * sz.height() / float(sz.width()))
+        pd = QImage(w * dpr, h * dpr, QImage.Format_RGB32)
+        pd.fill(Qt.white)
+        p = QPainter(pd)
+        rend.render(p)
+        p.end()
+        img = QPixmap.fromImage(pd)
+        img.setDevicePixelRatio(dpr)
+    return img
 
 
 class ImageView(QDialog):
@@ -146,6 +164,7 @@ class ImagePopup(object):
             if not d.isVisible():
                 self.dialogs.remove(d)
 
+
 if __name__ == '__main__':
     import sys
     from calibre.gui2 import Application