[UX] Add spread/pinch & font increase/decrease to gesture manager (#5188)

* Add spread/pinch gesture to gesture manager
ability to disable: 
https://www.mobileread.com/forums/showthread.php?t=321818
https://github.com/koreader/koreader/pull/4815#issuecomment-478462416

* Add increase/decrease font size action gesture
https://github.com/koreader/koreader/issues/4727#issuecomment-475950484

frontend/apps/reader/modules/readerfont.lua

@@ -94,33 +94,6 @@ function ReaderFont:init()
     self.ui.menu:registerToMainMenu(self)
 end
 
-function ReaderFont:onReaderReady()
-    self:setupTouchZones()
-end
-
-function ReaderFont:setupTouchZones()
-    if Device:isTouchDevice() then
-        self.ui:registerTouchZones({
-            {
-                id = "id_spread",
-                ges = "spread",
-                screen_zone = {
-                    ratio_x = 0, ratio_y = 0, ratio_w = 1, ratio_h = 1,
-                },
-                handler = function(ges) return self:onAdjustSpread(ges) end
-            },
-            {
-                id = "id_pinch",
-                ges = "pinch",
-                screen_zone = {
-                    ratio_x = 0, ratio_y = 0, ratio_w = 1, ratio_h = 1,
-                },
-                handler = function(ges) return self:onAdjustPinch(ges) end
-            },
-        })
-    end
-end
-
 function ReaderFont:onSetDimensions(dimen)
     self.dimen = dimen
 end
@@ -338,25 +311,31 @@ function ReaderFont:addToMainMenu(menu_items)
     }
 end
 
-function ReaderFont:onAdjustSpread(ges)
-    local step = math.ceil(2 * #self.steps * ges.distance / self.gestureScale)
-    local delta_int = self.steps[step] or self.steps[#self.steps]
-    local info = Notification:new{text = _("Increasing font size…")}
-    UIManager:show(info)
-    UIManager:forceRePaint()
-    self:onChangeSize("increase", delta_int)
-    UIManager:close(info)
-    return true
-end
-
-function ReaderFont:onAdjustPinch(ges)
+-- direction +1 - increase font size
+-- direction -1 - decrease front size
+function ReaderFont:onAdjustFontSize(ges, direction)
+    if ges.distance == nil then
+        ges.distance = 1
+    end
+    if direction ~= -1 and direction ~= 1 then
+        -- set default value (increase frontlight)
+        direction = 1
+    end
     local step = math.ceil(2 * #self.steps * ges.distance / self.gestureScale)
     local delta_int = self.steps[step] or self.steps[#self.steps]
-    local info = Notification:new{text = _("Decreasing font size…")}
-    UIManager:show(info)
-    UIManager:forceRePaint()
-    self:onChangeSize("decrease", delta_int)
-    UIManager:close(info)
+    if direction == 1 then
+        local info = Notification:new{text = _("Increasing font size…")}
+        UIManager:show(info)
+        UIManager:forceRePaint()
+        self:onChangeSize("increase", delta_int)
+        UIManager:close(info)
+    else
+        local info = Notification:new{text = _("Decreasing font size…")}
+        UIManager:show(info)
+        UIManager:forceRePaint()
+        self:onChangeSize("decrease", delta_int)
+        UIManager:close(info)
+    end
     return true
 end
 

frontend/apps/reader/modules/readergesture.lua

@@ -85,6 +85,9 @@ local action_strings = {
     zoom_content = _("Zoom to fit content"),
     zoom_page = _("Zoom to fit page"),
 
+    increase_font = _("Increase font size"),
+    decrease_font = _("Decrease font size"),
+
     folder_up = _("Folder up"),
     show_plus_menu = _("Show plus menu"),
     folder_shortcuts = _("Folder shortcuts"),
@@ -209,6 +212,8 @@ function ReaderGesture:init()
         two_finger_swipe_northwest = "ignore",
         two_finger_swipe_southeast = "ignore",
         two_finger_swipe_southwest = "ignore",
+        spread_gesture = self.ges_mode == "gesture_reader" and "increase_font" or "ignore",
+        pinch_gesture = self.ges_mode == "gesture_reader" and "decrease_font" or "ignore",
     }
     local gm = G_reader_settings:readSetting(self.ges_mode)
     if gm == nil then G_reader_settings:saveSetting(self.ges_mode, {}) end
@@ -617,6 +622,19 @@ Default value: %1]]), GestureDetector.SWIPE_INTERVAL/1000),
                 },
             },
         })
+        table.insert(menu_items.gesture_manager.sub_item_table, {
+            text = _("Spread and pinch"),
+            sub_item_table = {
+                {
+                    text_func = function() return actionTextFunc("spread_gesture", _("Spread")) end,
+                    sub_item_table = self:buildMenu("spread_gesture", self.default_gesture["spread_gesture"]),
+                },
+                {
+                    text_func = function() return actionTextFunc("pinch_gesture", _("Pinch")) end,
+                    sub_item_table = self:buildMenu("pinch_gesture", self.default_gesture["pinch_gesture"]),
+                },
+            }
+        })
     end
 end
 
@@ -685,6 +703,9 @@ function ReaderGesture:buildMenu(ges, default)
         {"wifi_off", Device:hasWifiToggle()},
         {"toggle_wifi", Device:hasWifiToggle(), true},
 
+        {"increase_font", not self.is_docless},
+        {"decrease_font", not self.is_docless, true},
+
         {"toggle_bookmark", not self.is_docless, true},
         {"toggle_page_flipping", not self.is_docless, true},
         {"toggle_reflow", not self.is_docless, true},
@@ -1101,7 +1122,12 @@ function ReaderGesture:setupGesture(ges, action)
                 "paging_swipe",
             }
         end
-
+    elseif ges == "spread_gesture" then
+        ges_type = "spread"
+        zone = zone_fullscreen
+    elseif ges == "pinch_gesture" then
+        ges_type = "pinch"
+        zone = zone_fullscreen
     else return
     end
     self:registerGesture(ges, action, ges_type, zone, overrides, direction, distance)
@@ -1370,6 +1396,10 @@ function ReaderGesture:gestureAction(action, ges)
                 timeout = 1,
             })
         end
+    elseif action == "increase_font" then
+        self.ui:handleEvent(Event:new("AdjustFontSize", ges, 1))
+    elseif action == "decrease_font" then
+        self.ui:handleEvent(Event:new("AdjustFontSize", ges, -1))
     elseif action == "suspend" then
         UIManager:suspend()
     elseif action == "exit" then