[fix] GestureDetector: add PAN_DELAYED_INTERVAL (#4666)

When multiswipes are enabled, this fixes the long-standing complaint that swiping to open the menu could unintentionally trigger some light panning. With the introduction of multiswipes, this problem has become more noticeable.

frontend/apps/reader/modules/readerpaging.lua

@@ -401,8 +401,12 @@ function ReaderPaging:onPan(_, ges)
             self.view:PanningStart(-ges.relative.x, -ges.relative.y)
         end
     elseif ges.direction == "north" or ges.direction == "south" then
-        self:onPanningRel(self.last_pan_relative_y - ges.relative.y)
-        self.last_pan_relative_y = ges.relative.y
+        local relative_type = "relative"
+        if self.ui.gesture and self.ui.gesture.multiswipes_enabled then
+            relative_type = "relative_delayed"
+        end
+        self:onPanningRel(self.last_pan_relative_y - ges[relative_type].y)
+        self.last_pan_relative_y = ges[relative_type].y
     end
     return true
 end

frontend/apps/reader/modules/readerrolling.lua

@@ -421,10 +421,14 @@ end
 
 function ReaderRolling:onPan(_, ges)
     if self.view.view_mode == "scroll" then
+        local distance_type = "distance"
+        if self.ui.gesture and self.ui.gesture.multiswipes_enabled then
+            distance_type = "distance_delayed"
+        end
         if ges.direction == "north" then
-            self:_gotoPos(self.current_pos + ges.distance)
+            self:_gotoPos(self.current_pos + ges[distance_type])
         elseif ges.direction == "south" then
-            self:_gotoPos(self.current_pos - ges.distance)
+            self:_gotoPos(self.current_pos - ges[distance_type])
         end
     end
     return true

frontend/device/gesturedetector.lua

@@ -53,6 +53,7 @@ local GestureDetector = {
     DOUBLE_TAP_INTERVAL = 300 * 1000,
     TWO_FINGER_TAP_DURATION = 300 * 1000,
     HOLD_INTERVAL = 500 * 1000,
+    PAN_DELAYED_INTERVAL = 500 * 1000,
     SWIPE_INTERVAL = 900 * 1000,
     -- pinch/spread direction table
     DIRECTION_TABLE = {
@@ -482,6 +483,7 @@ function GestureDetector:handlePan(tev)
         return self:handleTwoFingerPan(tev)
     else
         local pan_direction, pan_distance = self:getPath(slot)
+        local tv_diff = self.last_tevs[slot].timev - self.first_tevs[slot].timev
 
         local pan_ev = {
             ges = "pan",
@@ -490,13 +492,30 @@ function GestureDetector:handlePan(tev)
                 x = 0,
                 y = 0,
             },
+            relative_delayed = {
+                -- default to pan 0
+                x = 0,
+                y = 0,
+            },
             pos = nil,
             direction = pan_direction,
             distance = pan_distance,
+            distance_delayed = 0,
             time = tev.timev,
         }
+
+        -- regular pan
         pan_ev.relative.x = tev.x - self.first_tevs[slot].x
         pan_ev.relative.y = tev.y - self.first_tevs[slot].y
+
+        -- delayed pan, used where necessary to reduce potential activation of panning
+        -- when swiping is intended (e.g., for the menu or for multiswipe)
+        if not ((tv_diff.sec == 0) and (tv_diff.usec < self.PAN_DELAYED_INTERVAL)) then
+            pan_ev.relative_delayed.x = tev.x - self.first_tevs[slot].x
+            pan_ev.relative_delayed.y = tev.y - self.first_tevs[slot].y
+            pan_ev.distance_delayed = pan_distance
+        end
+
         pan_ev.pos = Geom:new{
             x = self.last_tevs[slot].x,
             y = self.last_tevs[slot].y,