fix performance issue of screensaver on Kobo

now loadDocument will not render the document and getCoverPageImage will
be much faster.

frontend/apps/reader/readerui.lua

@@ -220,9 +220,9 @@ function ReaderUI:init()
             document = self.document,
         })
     else
-        -- make sure we load document first before calling any callback
+        -- make sure we render document first before calling any callback
         table.insert(self.postInitCallback, function()
-            self.document:loadDocument()
+            self.document:render()
         end)
         -- typeset controller
         table.insert(self, ReaderTypeset:new{

frontend/document/credocument.lua

@@ -108,20 +108,25 @@ function CreDocument:init()
     -- set fallback font face
     self._document:setStringProperty("crengine.font.fallback.face", self.fallback_font)
 
+    -- set visible page count in landscape
+    if math.max(Screen:getWidth(), Screen:getHeight()) / Screen:getDPI()
+        < DCREREADER_TWO_PAGE_THRESHOLD then
+        self:setVisiblePageCount(1)
+    end
+
     self.is_open = true
     self.info.has_pages = false
     self:_readMetadata()
     self.info.configurable = true
 end
 
-function CreDocument:loadDocument()
+function CreDocument:render()
+    -- load document before rendering
     self._document:loadDocument(self.file)
+    self._document:renderDocument()
     if not self.info.has_pages then
         self.info.doc_height = self._document:getFullHeight()
     end
-    if math.max(Screen:getWidth(),Screen:getHeight())/Screen:getDPI() < DCREREADER_TWO_PAGE_THRESHOLD then
-        self:setVisiblePageCount(1)
-    end
 end
 
 function CreDocument:close()
@@ -133,6 +138,7 @@ function CreDocument:getPageCount()
 end
 
 function CreDocument:getCoverPageImage()
+    -- don't need to render document in order to get cover image
     self._document:loadDocument(self.file)
     local data, size = self._document:getCoverPageImageData()
     if data and size then

koreader-base

@@ -1 +1 @@
-Subproject commit 446aa931453c0c18ecdc7e94cf827730de6bd31d
+Subproject commit 11a738de463d3c3e9c776ab10a35447bb445d717