[UX] Gesture manager: add actions - prev/next chapter (#4692)

Also adds rudimentary support for these in ReaderPaging.

frontend/apps/reader/modules/readergesture.lua

@@ -23,6 +23,8 @@ local action_strings = {
     page_jmp_back_1 = _("Previous page"),
     page_jmp_fwd_10 = _("Forward 10 pages"),
     page_jmp_fwd_1 = _("Next page"),
+    prev_chapter = _("Previous chapter"),
+    next_chapter = _("Next chapter"),
     go_to = _("Go to"),
     skim = _("Skim"),
     back = _("Back"),
@@ -247,6 +249,8 @@ function ReaderGesture:buildMenu(ges, default)
         {"page_jmp_back_1", not self.is_docless},
         {"page_jmp_fwd_10", not self.is_docless},
         {"page_jmp_fwd_1", not self.is_docless},
+        {"prev_chapter", not self.is_docless},
+        {"next_chapter", not self.is_docless},
         {"go_to", true},
         {"skim", not self.is_docless},
         {"back", true},
@@ -513,6 +517,10 @@ function ReaderGesture:gestureAction(action)
         self:pageUpdate(-10)
     elseif action == "page_jmp_back_1" then
         self:pageUpdate(-1)
+    elseif action == "next_chapter" then
+        self.ui:handleEvent(Event:new("GotoNextChapter"))
+    elseif action == "prev_chapter" then
+        self.ui:handleEvent(Event:new("GotoPrevChapter"))
     elseif action == "go_to" then
         self.ui:handleEvent(Event:new("ShowGotoDialog"))
     elseif action == "skim" then

frontend/apps/reader/modules/readerpaging.lua

@@ -959,4 +959,26 @@ function ReaderPaging:onGotoPercentage(percentage)
     return true
 end
 
+-- These might need additional work to behave fine in scroll
+-- mode, and other zoom modes than Fit page
+function ReaderPaging:onGotoNextChapter()
+    local pageno = self.current_page
+    local new_page = self.ui.toc:getNextChapter(pageno, 0)
+    if new_page then
+        self.ui.link:addCurrentLocationToStack()
+        self:onGotoPage(new_page)
+    end
+    return true
+end
+
+function ReaderPaging:onGotoPrevChapter()
+    local pageno = self.current_page
+    local new_page = self.ui.toc:getPreviousChapter(pageno, 0)
+    if new_page then
+        self.ui.link:addCurrentLocationToStack()
+        self:onGotoPage(new_page)
+    end
+    return true
+end
+
 return ReaderPaging

frontend/apps/reader/modules/readerrolling.lua

@@ -285,13 +285,13 @@ function ReaderRolling:setupTouchZones()
             id = "double_tap_forward",
             ges = "double_tap",
             screen_zone = forward_double_tap_zone,
-            handler = function() return self:onDoubleTapForward() end
+            handler = function() return self:onGotoNextChapter() end
         },
         {
             id = "double_tap_backward",
             ges = "double_tap",
             screen_zone = backward_double_tap_zone,
-            handler = function() return self:onDoubleTapBackward() end
+            handler = function() return self:onGotoPrevChapter() end
         },
         {
             id = "rolling_swipe",
@@ -448,7 +448,7 @@ function ReaderRolling:onResume()
     self:updateBatteryState()
 end
 
-function ReaderRolling:onDoubleTapForward()
+function ReaderRolling:onGotoNextChapter()
     local visible_page_count = self.ui.document:getVisiblePageCount()
     local pageno = self.current_page + (visible_page_count > 1 and 1 or 0)
     local new_page = self.ui.toc:getNextChapter(pageno, 0)
@@ -459,7 +459,7 @@ function ReaderRolling:onDoubleTapForward()
     return true
 end
 
-function ReaderRolling:onDoubleTapBackward()
+function ReaderRolling:onGotoPrevChapter()
     local pageno = self.current_page
     local new_page = self.ui.toc:getPreviousChapter(pageno, 0)
     if new_page then