UIManager: Don't block gestures for new widgets when input is disabled (#11122)

They'll be disabled again when the widget in question is dismissed.

This exposes a couple of semi-obvious but edge-casey footguns to the user, but a hardened implementation is way uglier. See PR for details.

frontend/device/devicelistener.lua

@@ -355,4 +355,10 @@ function DeviceListener:onFullRefresh()
     UIManager:setDirty(nil, "full")
 end
 
+-- On resume, make sure we restore Gestures handling in InputContainer, to avoid confusion for scatter-brained users ;).
+-- It's also helpful when the IgnoreTouchInput event is emitted by Dispatcher through other means than Gestures.
+function DeviceListener:onResume()
+    UIManager:setIgnoreTouchInput(false)
+end
+
 return DeviceListener

frontend/ui/screensaver.lua

@@ -753,6 +753,9 @@ function Screensaver:show()
         widget = addOverlayMessage(widget, message_height, self.overlay_message)
     end
 
+    -- NOTE: Make sure InputContainer gestures are not disabled, to prevent stupid interactions with UIManager on close.
+    UIManager:setIgnoreTouchInput(false)
+
     if widget then
         self.screensaver_widget = ScreenSaverWidget:new{
             widget = widget,

frontend/ui/uimanager.lua

@@ -42,6 +42,7 @@ local UIManager = {
     _gated_quit = nil,
     _prevent_standby_count = 0,
     _prev_prevent_standby_count = 0,
+    _input_gestures_disabled = false,
 
     event_hook = require("ui/hook_container"):new()
 }
@@ -113,6 +114,12 @@ function UIManager:init()
     self:unsetRunForeverMode()
 end
 
+-- Crappy wrapper because of circular dependencies
+function UIManager:setIgnoreTouchInput(state)
+    local InputContainer = require("ui/widget/container/inputcontainer")
+    InputContainer:setIgnoreTouchInput(state)
+end
+
 --[[--
 Registers and shows a widget.
 
@@ -165,6 +172,13 @@ function UIManager:show(widget, refreshtype, refreshregion, x, y, refreshdither)
     Input.disable_double_tap = widget.disable_double_tap ~= false
     -- a widget may override tap interval (when it doesn't, nil restores the default)
     Input.tap_interval_override = widget.tap_interval_override
+    -- If input was disabled, re-enable it while this widget is shown so we can actually interact with it.
+    -- The only thing that could actually call show in this state is something automatic, so we need to be able to deal with it.
+    if UIManager._input_gestures_disabled then
+        logger.dbg("Gestures were disabled, temporarily re-enabling them to allow interaction with widget")
+        self:setIgnoreTouchInput(false)
+        widget._restored_input_gestures = true
+    end
 end
 
 --[[--
@@ -245,6 +259,10 @@ function UIManager:close(widget, refreshtype, refreshregion, refreshdither)
         end
         self:_refresh(refreshtype, refreshregion, refreshdither)
     end
+    if widget._restored_input_gestures then
+        logger.dbg("Widget is gone, disabling gesture handling again")
+        self:setIgnoreTouchInput(true)
+    end
 end
 
 --- Shift the execution times of all scheduled tasks.

frontend/ui/widget/container/inputcontainer.lua

@@ -41,6 +41,7 @@ local Geom = require("ui/geometry")
 local GestureRange = require("ui/gesturerange")
 local UIManager = require("ui/uimanager")
 local WidgetContainer = require("ui/widget/container/widgetcontainer")
+local logger = require("logger")
 local Screen = Device.screen
 local _ = require("gettext")
 
@@ -304,41 +305,56 @@ end
 --       [1] The most common implementation you'll see is a NOP for ReaderUI modules that defer gesture handling to ReaderUI.
 --           Notification also implements a simple one to dismiss notifications on any user input,
 --           which is something that doesn't impede our goal, which is why we don't need to deal with it.
-function InputContainer:onIgnoreTouchInput(toggle)
-    local Notification = require("ui/widget/notification")
-    if toggle == false then
+function InputContainer:setIgnoreTouchInput(state)
+    logger.dbg("InputContainer:setIgnoreTouchInput", state)
+    if state == true then
+        -- Replace the onGesture handler w/ the minimal one if that's not already the case
+        if not InputContainer._onGesture then
+            InputContainer._onGesture = InputContainer.onGesture
+            InputContainer.onGesture = InputContainer._onGestureFiltered
+            -- Notify UIManager so it knows what to do if a random popup shows up
+            UIManager._input_gestures_disabled = true
+            logger.dbg("Disabled InputContainer gesture handler")
+
+            -- Notify our caller that the state changed
+            return true
+        end
+    elseif state == false then
         -- Restore the proper onGesture handler if we disabled it
         if InputContainer._onGesture then
             InputContainer.onGesture = InputContainer._onGesture
             InputContainer._onGesture = nil
-            Notification:notify("Restored touch input")
+            UIManager._input_gestures_disabled = false
+            logger.dbg("Restored InputContainer gesture handler")
+
+            return true
         end
-    elseif toggle == true then
-        -- Replace the onGesture handler w/ the minimal one if that's not already the case
-        if not InputContainer._onGesture then
-            InputContainer._onGesture = InputContainer.onGesture
-            InputContainer.onGesture = InputContainer._onGestureFiltered
-            Notification:notify("Disabled touch input")
+    end
+
+    -- We did not actually change the state
+    return false
+end
+
+-- And the matching Event handler
+function InputContainer:onIgnoreTouchInput(toggle)
+    local Notification = require("ui/widget/notification")
+    if toggle == true then
+        if self:setIgnoreTouchInput(true) then
+            Notification:notify(_("Disabled touch input"))
+        end
+    elseif toggle == false then
+        if self:setIgnoreTouchInput(false) then
+            Notification:notify(_("Restored touch input"))
         end
     else
         -- Toggle the current state
-        if InputContainer._onGesture then
-            return self:onIgnoreTouchInput(false)
-        else
-            return self:onIgnoreTouchInput(true)
-        end
+        return self:onIgnoreTouchInput(not UIManager._input_gestures_disabled)
     end
 
     -- We only affect the base class, once is enough ;).
     return true
 end
 
-function InputContainer:onResume()
-    -- Always restore touch input on resume, to avoid confusion for scatter-brained users ;).
-    -- It's also helpful when the IgnoreTouchInput event is emitted by Dispatcher through other means than Gestures.
-    self:onIgnoreTouchInput(false)
-end
-
 function InputContainer:onInput(input, ignore_first_hold_release)
     local InputDialog = require("ui/widget/inputdialog")
     self.input_dialog = InputDialog:new{