Viewer: Allow double clicking or long tapping on images to view then in a new window. Fixes #1872759 [E-book viewer: double clicking on image to evoke "View image" window.](https://bugs.launchpad.net/calibre/+bug/1872759)

manual/viewer.rst

@@ -137,6 +137,14 @@ right clicking and selecting :guilabel:`Copy` to copy to the clipboard.  The cop
 material can be pasted into another application as plain text and images.
 
 
+Zooming in on images
+----------------------------
+
+You can zoom in to show an image at full size in a separate window by either
+double clicking or long tapping on it. You can also right click on it and
+choose :guilabel:`View Image`.
+
+
 Non re-flowable content
 --------------------------
 

src/pyj/read_book/flow_mode.pyj

@@ -2,8 +2,6 @@
 # License: GPL v3 Copyright: 2016, Kovid Goyal <kovid at kovidgoyal.net>
 from __python__ import bound_methods, hash_literals
 
-from select import word_at_point
-
 from dom import set_css
 from read_book.globals import current_spine_item, get_boss
 from read_book.settings import opts
@@ -429,13 +427,6 @@ def handle_gesture(gesture):
         scroll_by_page(-1)
     elif gesture.type is 'next-page':
         scroll_by_page(1)
-    elif gesture.type is 'long-tap':
-        r = word_at_point(gesture.viewport_x, gesture.viewport_y)
-        if r:
-            s = document.getSelection()
-            s.removeAllRanges()
-            s.addRange(r)
-            get_boss().send_message('lookup_word', word=str(r))
 
 
 anchor_funcs = {

src/pyj/read_book/iframe.pyj

@@ -6,7 +6,7 @@ import traceback
 from gettext import gettext as _
 from select import (
     extend_selection_after_scroll, selection_extents, selection_extents_at_point,
-    set_selections_extents_to
+    set_selections_extents_to, word_at_point
 )
 
 from fs_images import fix_fullscreen_svg_images
@@ -261,9 +261,23 @@ class IframeBoss:
             self.send_message('show_chrome')
         elif gesture.type is 'pinch':
             self.send_message('bump_font_size', increase=gesture.direction is 'out')
+        elif gesture.type is 'long-tap':
+            self.handle_long_tap(gesture)
         else:
             self._handle_gesture(gesture)
 
+    def handle_long_tap(self, gesture):
+        elements = get_elements(gesture.viewport_x, gesture.viewport_y)
+        if elements.img:
+            self.send_message('view_image', calibre_src=elements.img)
+            return
+        r = word_at_point(gesture.viewport_x, gesture.viewport_y)
+        if r:
+            s = document.getSelection()
+            s.removeAllRanges()
+            s.addRange(r)
+            self.send_message('lookup_word', word=str(r))
+
     def gesture_from_margin(self, data):
         self.handle_gesture(data.gesture)
 
@@ -363,6 +377,8 @@ class IframeBoss:
     def content_loaded_stage2(self):
         reset_find_caches()
         self.connect_links()
+        if runtime.is_standalone_viewer:
+            self.listen_for_image_double_clicks()
         self.content_ready = True
         # this is the loading styles used to suppress scrollbars during load
         # added in unserialize_html
@@ -543,6 +559,15 @@ class IframeBoss:
             for a in document.body.querySelectorAll('a[target]'):
                 a.removeAttribute('target')
 
+    def listen_for_image_double_clicks(self):
+        for img in document.querySelectorAll('img, image'):
+            img.addEventListener('dblclick', self.image_double_clicked, {'passive': True})
+
+    def image_double_clicked(self, ev):
+        img = ev.currentTarget
+        if img.dataset.calibreSrc:
+            self.send_message('view_image', calibre_src=img.dataset.calibreSrc)
+
     def link_activated(self, evt):
         link_attr = 'data-' + self.book.manifest.link_uid
         try:

src/pyj/read_book/view.pyj

@@ -269,6 +269,10 @@ class View:
                 if ui_operations.copy_selection:
                     ui_operations.copy_selection(data.text)
             ,
+            'view_image': def(data):
+                if ui_operations.view_image:
+                    ui_operations.view_image(data.calibre_src)
+            ,
         }
         entry_point = None if runtime.is_standalone_viewer else 'read_book.iframe'
         if runtime.is_standalone_viewer: