new cache organization in preparation for more complex tile data

in order to use the tile cache for variable zoomed tiles, we need more
flexibility. thus, now cache tiles are hashed (well, in fact it's a
concatenation) of their metadata.

also, we close pages right after opening them - there was no re-use
before and now we have opening and closing at one place. this should
also make it easier for the garbage collector.

reader.lua

@@ -51,6 +51,7 @@ rcount = 5
 rcountmax = 5
 
 globalzoom = -1
+globalgamma = -1.0
 
 if optarg["d"] == "k3" then
 	-- for now, the only difference is the additional input device
@@ -66,6 +67,10 @@ else
 	input.open("/dev/input/event1")
 end
 
+if optarg["G"] ~= nil then
+	globalgamma = optarg["G"]
+end
+
 doc = pdf.openDocument(ARGV[optind], optarg["p"] or "")
 
 print("pdf has "..doc:getPages().." pages.")
@@ -73,12 +78,11 @@ print("pdf has "..doc:getPages().." pages.")
 fb = einkfb.open("/dev/fb0")
 width, height = fb:getSize()
 
-init_tilecache()
-
 nulldc = pdf.newDC()
 
-function setzoom(cacheslot)
+function setzoom(page, cacheslot)
-	local pwidth, pheight = cache[cacheslot].page:getSize(nulldc)
+	local dc = pdf.newDC()
+	local pwidth, pheight = page:getSize(nulldc)
 
 	-- default zoom: fit to page
 	local zoom = width / pwidth
@@ -90,18 +94,19 @@ function setzoom(cacheslot)
 		offset_y = 0
 	end
 
-	cache[cacheslot].dc:setZoom(zoom)
+	dc:setZoom(zoom)
-	cache[cacheslot].dc:setOffset(offset_x, offset_y)
+	dc:setOffset(offset_x, offset_y)
 
 	-- set gamma here, we don't have any other good place for this right now:
-	if optarg["G"] then
+	if globalgamma ~= -1.0 then
-		print("gamma correction: "..optarg["G"])
+		print("gamma correction: "..globalgamma)
-		cache[cacheslot].dc:setGamma(optarg["G"])
+		dc:setGamma(globalgamma)
 	end
+	return dc
 end
 
 function show(no)
-	local slot = draworcache(no)
+	local slot = draworcache(no,globalzoom,0,0,width,height,globalgamma)
 	fb:blitFullFrom(cache[slot].bb)
 	if rcount == rcountmax then
 		print("full refresh")
@@ -123,22 +128,18 @@ function goto(no)
 	show(no)
 	if no < doc:getPages() then
 		-- always pre-cache next page
-		draworcache(no+1)
+		draworcache(no+1,globalzoom,0,0,width,height,globalgamma)
 	end
 end
 
 function modify_gamma(offset)
-	local slot = slot_visible
+	if globalgamma == -1 then
-	local gamma = cache[slot].dc:getGamma();
+		globalgamma = 1
-	if gamma == -1 then
-		gamma = 1
 	end
-	local no = cache[slot].no
+	print("modify_gamma, gamma="..globalgamma.." offset="..offset)
-	print("modify_gamma "..no.." slot="..slot.." gamma="..gamma.." offset="..offset)
+	globalgamma = globalgamma + offset;
-	gamma = gamma + offset;
+	clearcache()
-	optarg["G"] = gamma; -- for next page
+	goto(pageno)
-	freecache()
-	goto(no)
 end
 
 function mainloop()
@@ -147,13 +148,9 @@ function mainloop()
 		if ev.type == EV_KEY and ev.value == EVENT_VALUE_KEY_PRESS then
 			local secs, usecs = util.gettime()
 			if ev.code == KEY_PAGEUP then
-				print(cache)
 				goto(pageno + 1)
-				print(cache)
 			elseif ev.code == KEY_PAGEDOWN then
-				print(cache)
 				goto(pageno - 1)
-				print(cache)
 			elseif ev.code == KEY_BACK then
 				return
 			elseif ev.code == KEY_UP then

tilecache.lua

@@ -1,64 +1,51 @@
 --[[
 a cache for rendered tiles
 ]]--
-
+cache_max_memsize = 1024*1024*5 -- 5MB tile cache
-function init_tilecache()
+cache_current_memsize = 0
-	cache = {
+cache = {}
-		{ age = 0, no = 0, bb = blitbuffer.new(width, height), dc = pdf.newDC(), page = nil },
+cache_max_age = 20
-		{ age = 0, no = 0, bb = blitbuffer.new(width, height), dc = pdf.newDC(), page = nil },
+function cacheclaim(size)
-		{ age = 0, no = 0, bb = blitbuffer.new(width, height), dc = pdf.newDC(), page = nil }
+	if(size > cache_max_memsize) then
-	}
+		error("too much memory claimed")
-end
+		return false
-function freecache()
+	end
-	for i = 1, #cache do
+	repeat
-		if cache[i].page ~= nil then
+		for k, v in pairs(cache) do
-			print("freeing slot="..i.." oldpage="..cache[i].no)
+			if v.age > 0 then
-			cache[i].page:close()
+				print("aging slot="..k)
-			cache[i].page = nil
+				v.age = v.age - 1
+			else
+				cache_current_memsize = cache_current_memsize - v.size
+				cache[k] = nil
+				break -- out of for loop
 			end
 		end
+	until cache_current_memsize + size <= cache_max_memsize
+	cache_current_memsize = cache_current_memsize + size
+	print("cleaned cache to fit new tile (size="..size..")")
+	return true
 end
-function checkcache(no)
+function draworcache(no, zoom, offset_x, offset_y, width, height, gamma)
-	for i = 1, #cache do
+	local hash = cachehash(no, zoom, offset_x, offset_y, width, height, gamma)
-		if cache[i].no == no and cache[i].page ~= nil then
+	if cache[hash] == nil then
-			print("cache hit: slot="..i.." page="..no)
+		cacheclaim(width * height / 2);
-			return i
+		cache[hash] = {
-		end
+			age = cache_max_age,
+			size = width * height / 2,
+			bb = blitbuffer.new(width, height)
+		}
+		print("drawing page="..no.." to slot="..hash)
+		local page = doc:openPage(no)
+		local dc = setzoom(page, hash)
+		page:draw(dc, cache[hash].bb, 0, 0)
+		page:close()
 	end
-	print("cache miss")
+	return hash
-	return nil
 end
-function cacheslot()
+function cachehash(no, zoom, offset_x, offset_y, width, height, gamma)
-	freeslot = nil
+	return no..'_'..zoom..'_'..offset_x..','..offset_y..'-'..width..'x'..height..'_'..gamma;
-	while freeslot == nil do
-		for i = 1, #cache do
-			if cache[i].age > 0 then
-				print("aging slot="..i)
-				cache[i].age = cache[i].age - 1
-			else
-				if cache[i].page ~= nil then
-					print("freeing slot="..i.." oldpage="..cache[i].no)
-					cache[i].page:close()
-					cache[i].page = nil
-				end
-				freeslot = i
-			end
-		end
-	end
-	print("returning free slot="..freeslot)
-	return freeslot
 end
-
+function clearcache()
-function draworcache(no)
+	cache = {}
-	local slot = checkcache(no)
-	if slot == nil then
-		slot = cacheslot()
-		cache[slot].no = no
-		cache[slot].age = #cache
-		cache[slot].page = doc:openPage(no)
-		setzoom(slot)
-		print("drawing page="..no.." to slot="..slot)
-		cache[slot].page:draw(cache[slot].dc, cache[slot].bb, 0, 0)
-	end
-	return slot
 end