Stash enableCPUCores in CanvasContext

Avoids requring Device direction in Document.

The method needs complete access to the Device object, though, so it's
just another layer of indirection, with an extra reference on the Device
object stashed in CanvasContext...
(much like it already does for Screen)

frontend/document/canvascontext.lua

@@ -35,6 +35,7 @@ The following key is required for a device object:
     * isColorEnabled() -> boolean
 ]]--
 function CanvasContext:init(device)
+    self.device = device
     self.screen = device.screen
     self.isAndroid = device.isAndroid
     self.isDesktop = device.isDesktop
@@ -45,7 +46,7 @@ function CanvasContext:init(device)
     self.hasSystemFonts = device.hasSystemFonts
     self:setColorRenderingEnabled(device.screen.isColorEnabled())
 
-    -- NOTE: Kobo's fb is BGR, not RGB. Handle the conversion in MuPDF if needed.
+    -- NOTE: At 32bpp, Kobo's fb is BGR, not RGB. Handle the conversion in MuPDF if needed.
     if device:hasBGRFrameBuffer() then
         self.is_bgr = true
         Mupdf.bgr = true
@@ -77,4 +78,8 @@ function CanvasContext:scaleBySize(px)
     return self.screen:scaleBySize(px)
 end
 
+function CanvasContext:enableCPUCores(amount)
+    return self.device:enableCPUCores(amount)
+end
+
 return CanvasContext

frontend/document/document.lua

@@ -1,7 +1,6 @@
 local Blitbuffer = require("ffi/blitbuffer")
 local CacheItem = require("cacheitem")
 local Configurable = require("configurable")
-local Device = require("device")
 local DocCache = require("document/doccache")
 local DrawContext = require("ffi/drawcontext")
 local CanvasContext = require("document/canvascontext")
@@ -413,7 +412,7 @@ function Document:renderPage(pageno, rect, zoom, rotation, gamma, render_mode, h
     end
 
     if hinting then
-        Device:enableCPUCores(2)
+        CanvasContext:enableCPUCores(2)
     end
     self:preRenderPage()
 
@@ -429,7 +428,7 @@ function Document:renderPage(pageno, rect, zoom, rotation, gamma, render_mode, h
             logger.warn("aborting, since we do not have a specification for that part")
             -- required part not given, so abort
             if hinting then
-                Device:enableCPUCores(1)
+                CanvasContext:enableCPUCores(1)
             end
             return
         end
@@ -474,7 +473,7 @@ function Document:renderPage(pageno, rect, zoom, rotation, gamma, render_mode, h
 
     self:postRenderPage()
     if hinting then
-        Device:enableCPUCores(1)
+        CanvasContext:enableCPUCores(1)
     end
     return tile
 end

frontend/document/koptinterface.lua

@@ -6,7 +6,6 @@ local CacheItem = require("cacheitem")
 local CanvasContext = require("document/canvascontext")
 local DataStorage = require("datastorage")
 local DEBUG = require("dbg")
-local Device = require("device")
 local DocCache = require("document/doccache")
 local Document = require("document/document")
 local FFIUtil = require("ffi/util")
@@ -111,7 +110,7 @@ function KoptInterface:waitForContext(kc)
 
     if waited or self.bg_thread then
         -- Background thread is done, go back to a single CPU core.
-        Device:enableCPUCores(1)
+        CanvasContext:enableCPUCores(1)
         self.bg_thread = nil
     end
 
@@ -392,7 +391,7 @@ function KoptInterface:renderOptimizedPage(doc, pageno, rect, zoom, rotation, re
     local cached = DocCache:check(hash, TileCacheItem)
     if not cached then
         if hinting then
-            Device:enableCPUCores(2)
+            CanvasContext:enableCPUCores(2)
         end
 
         local page_size = Document.getNativePageDimensions(doc, pageno)
@@ -425,7 +424,7 @@ function KoptInterface:renderOptimizedPage(doc, pageno, rect, zoom, rotation, re
         DocCache:insert(hash, tile)
 
         if hinting then
-            Device:enableCPUCores(1)
+            CanvasContext:enableCPUCores(1)
         end
 
         return tile
@@ -464,7 +463,7 @@ function KoptInterface:hintReflowedPage(doc, pageno, zoom, rotation, gamma, rend
     local cached = DocCache:check(hash)
     if not cached then
         if hinting then
-            Device:enableCPUCores(2)
+            CanvasContext:enableCPUCores(2)
         end
 
         local kc = self:createContext(doc, pageno, bbox)