Speed up page turning on big cre documents

frontend/apps/reader/modules/readerrolling.lua

@@ -99,6 +99,9 @@ function ReaderRolling:init()
     end)
     table.insert(self.ui.postReaderCallback, function()
         self:updatePos()
+        -- Disable crengine internal history, with required redraw
+        self.ui.document:enableInternalHistory(false)
+        self:onRedrawCurrentView()
     end)
     self.ui.menu:registerToMainMenu(self)
 end
@@ -566,10 +569,16 @@ function ReaderRolling:onSetDimensions(dimen)
 end
 
 function ReaderRolling:onChangeScreenMode(mode)
+    -- We need to temporarily re-enable internal history as crengine
+    -- uses it to reposition after resize
+    self.ui.document:enableInternalHistory(true)
     self.ui:handleEvent(Event:new("SetScreenMode", mode))
     self.ui.document:setViewDimen(Screen:getSize())
     self:onChangeViewMode()
     self:onUpdatePos()
+    -- Re-disable internal history, with required redraw
+    self.ui.document:enableInternalHistory(false)
+    self:onRedrawCurrentView()
 end
 
 function ReaderRolling:onColorRenderingUpdate()

frontend/document/credocument.lua

@@ -540,6 +540,19 @@ function CreDocument:findText(pattern, origin, reverse, caseInsensitive)
         pattern, origin, reverse, caseInsensitive and 1 or 0)
 end
 
+function CreDocument:enableInternalHistory(toggle)
+    -- Setting this to 0 unsets crengine internal bookmarks highlighting,
+    -- and as a side effect, disable internal history and the need to build
+    -- a bookmark at each page turn: this speeds up a lot page turning
+    -- and menu opening on big books.
+    -- It has to be called late in the document opening process, and setting
+    -- it to false needs to be followed by a redraw.
+    -- It needs to be temporarily re-enabled on page resize for crengine to
+    -- keep track of position in page and restore it after resize.
+    logger.dbg("CreDocument: set bookmarks highlight and internal history", toggle)
+    self._document:setIntProperty("crengine.highlight.bookmarks", toggle and 2 or 0)
+end
+
 function CreDocument:register(registry)
     registry:addProvider("azw", "application/vnd.amazon.mobi8-ebook", self, 90)
     registry:addProvider("chm", "application/vnd.ms-htmlhelp", self, 90)