From 65b1c5ac57639347e6bd5f3316fb26208762d37a Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Wed, 23 Apr 2014 10:31:36 +0530
Subject: [PATCH] E-book viewer: When in flow mode, handle swiping on the
 touchscreen differently. Swiping now scrolls line by line in flow mode
 instead of page by page. If you wish to scroll page by page in flow mode, tap
 instead of swiping.

---
 src/calibre/gui2/viewer/gestures.py | 36 ++++++++++++++++++++++++++++-
 1 file changed, 35 insertions(+), 1 deletion(-)

diff --git a/src/calibre/gui2/viewer/gestures.py b/src/calibre/gui2/viewer/gestures.py
index 751f4383ed..55fa249960 100644
--- a/src/calibre/gui2/viewer/gestures.py
+++ b/src/calibre/gui2/viewer/gestures.py
@@ -62,7 +62,8 @@ class Help(QDialog):  # {{{
 
             <dt>Swipe</dt>
             <dd>Swipe to the left to go to the next page and to the right to go to the previous page.
-            This mimics turning pages in a paper book.</dd>
+            This mimics turning pages in a paper book. When the viewer is not in paged mode, swiping
+            scrolls the text line by line instead of page by page.</dd>
 
             <dt>Pinch</dt>
             <dd>Pinch in or out to decrease or increase the font size</dd>
@@ -115,6 +116,12 @@ class TouchPoint(object):
         axis = (Left, Right) if xabs > yabs else (Up, Down)
         return axis[0 if d < 0 else 1]
 
+    @property
+    def swipe_live(self):
+        x_movement = self.current_screen_position.x() - self.previous_screen_position.x()
+        y_movement = self.current_screen_position.y() - self.previous_screen_position.y()
+        return (x_movement, y_movement)
+
 def get_pinch(p1, p2):
     starts = [p1.start_screen_position, p2.start_screen_position]
     ends = [p1.current_screen_position, p2.current_screen_position]
@@ -132,6 +139,7 @@ class State(QObject):
 
     tapped = pyqtSignal(object)
     swiped = pyqtSignal(object)
+    swiping = pyqtSignal(object, object)
     pinched = pyqtSignal(object)
     tap_hold_started = pyqtSignal(object)
     tap_hold_updated = pyqtSignal(object)
@@ -175,6 +183,9 @@ class State(QObject):
             self.clear()
         else:
             self.check_for_holds()
+            if {Swipe, SwipeAndHold} & self.possible_gestures:
+                tp = next(self.touch_points.itervalues())
+                self.swiping.emit(*tp.swipe_live)
 
     def check_for_holds(self):
         if not {SwipeAndHold, TapAndHold} & self.possible_gestures:
@@ -247,6 +258,7 @@ class GestureHandler(QObject):
         self.last_swipe_hold_update = None
         self.state.swiped.connect(self.handle_swipe)
         self.state.tapped.connect(self.handle_tap)
+        self.state.swiping.connect(self.handle_swiping)
         self.state.tap_hold_started.connect(partial(self.handle_tap_hold, 'start'))
         self.state.tap_hold_updated.connect(partial(self.handle_tap_hold, 'update'))
         self.state.tap_hold_finished.connect(partial(self.handle_tap_hold, 'end'))
@@ -314,9 +326,29 @@ class GestureHandler(QObject):
         if self.close_open_menu():
             return
         view = self.parent()
+        if not view.document.in_paged_mode:
+            return
         func = {Left:'next_page', Right: 'previous_page', Up:'goto_previous_section', Down:'goto_next_section'}[direction]
         getattr(view, func)()
 
+    def handle_swiping(self, x, y):
+        if max(abs(x), abs(y)) < 1:
+            return
+        view = self.parent()
+        if view.document.in_paged_mode:
+            return
+        ydirection = Up if y < 0 else Down
+        if view.manager is not None and abs(y) > 0:
+            if ydirection is Up and view.document.at_bottom:
+                view.manager.next_document()
+                return
+            elif ydirection is Down and view.document.at_top:
+                view.manager.previous_document()
+                return
+        view.scroll_by(x=-x, y=-y)
+        if view.manager is not None:
+            view.manager.scrolled(view.scroll_fraction)
+
     def current_position(self, tp):
         return self.parent().mapFromGlobal(tp.current_screen_position.toPoint())
 
@@ -346,6 +378,8 @@ class GestureHandler(QObject):
 
     def handle_swipe_hold(self, action, direction):
         view = self.parent()
+        if not view.document.in_paged_mode:
+            return
         if action == 'start':
             self.last_swipe_hold_update = time.time()
             try: