2
0
mirror of https://github.com/koreader/koreader synced 2024-11-16 06:12:56 +00:00
koreader/frontend/ui/widget/imagewidget.lua
Hans-Werner Hilse 0c80537003 allow image widgets to do alpha-blitting
when the image (e.g. a PNG) does contain an alpha channel, that can
be honored by ImageWidget. It doesn't do so by default for compatibility
(arguably, we should change that in the future), it has to be enabled
by setting the "alpha" property to "true" (boolean, not string).
2014-11-28 15:37:11 +00:00

134 lines
3.7 KiB
Lua

local Widget = require("ui/widget/widget")
local Screen = require("device").screen
local CacheItem = require("cacheitem")
local Mupdf = require("ffi/mupdf")
local Geom = require("ui/geometry")
local Cache = require("cache")
local DEBUG = require("dbg")
local ImageCache = Cache:new{
max_memsize = 2*1024*1024, -- 2M of image cache
current_memsize = 0,
cache = {},
-- this will hold the LRU order of the cache
cache_order = {}
}
local ImageCacheItem = CacheItem:new{}
function ImageCacheItem:onFree()
if self.bb.free then
DEBUG("free image blitbuffer", self.bb)
self.bb:free()
end
end
--[[
ImageWidget shows an image from a file
--]]
local ImageWidget = Widget:new{
file = nil,
image = nil,
invert = nil,
dim = nil,
hide = nil,
-- if width or height is given, image will rescale to the given size
width = nil,
height = nil,
-- if autoscale is true image will be rescaled according to screen dpi
autoscale = false,
-- when alpha is set to true, alpha values from the image will be honored
alpha = false,
_bb = nil
}
function ImageWidget:_loadimage()
self._bb = self.image
end
function ImageWidget:_loadfile()
local itype = string.lower(string.match(self.file, ".+%.([^.]+)") or "")
if itype == "png" or itype == "jpg" or itype == "jpeg"
or itype == "tiff" then
local hash = "image|"..self.file.."|"..(self.width or "").."|"..(self.height or "")
local cache = ImageCache:check(hash)
if cache then
-- hit cache
self._bb = cache.bb
else
-- cache this image
DEBUG("cache", hash)
local cache = ImageCacheItem:new{
bb = Mupdf.renderImageFile(self.file, self.width, self.height),
}
cache.size = cache.bb.pitch * cache.bb.h * cache.bb:getBpp() / 8
ImageCache:insert(hash, cache)
self._bb = cache.bb
end
else
error("Image file type not supported.")
end
end
function ImageWidget:_render()
if self.image then
self:_loadimage()
elseif self.file then
self:_loadfile()
else
error("cannot render image")
end
local native_w, native_h = self._bb:getWidth(), self._bb:getHeight()
local scaled_w, scaled_h = self.width, self.height
if self.autoscale then
local dpi_scale = Screen:getDPI() / 167
-- rounding off to power of 2 to avoid alias with pow(2, floor(log(x)/log(2))
local scale = math.pow(2, math.max(0, math.floor(math.log(dpi_scale)/0.69)))
scaled_w, scaled_h = scale * native_w, scale * native_h
end
if (scaled_w and scaled_w ~= native_w) or (scaled_h and scaled_h ~= native_h) then
self._bb = self._bb:scale(scaled_w or native_w, scaled_h or native_h)
end
end
function ImageWidget:getSize()
self:_render()
return Geom:new{ w = self._bb:getWidth(), h = self._bb:getHeight() }
end
function ImageWidget:rotate(degree)
self:_render()
self._bb:rotate(degree)
end
function ImageWidget:paintTo(bb, x, y)
if self.hide then return end
-- self:_reader is called in getSize method
local size = self:getSize()
self.dimen = Geom:new{
x = x, y = y,
w = size.w,
h = size.h
}
if self.alpha == true then
bb:alphablitFrom(self._bb, x, y, 0, 0, size.w, size.h)
else
bb:blitFrom(self._bb, x, y, 0, 0, size.w, size.h)
end
if self.invert then
bb:invertRect(x, y, size.w, size.h)
end
if self.dim then
bb:dimRect(x, y, size.w, size.h)
end
end
function ImageWidget:free()
if self.image then
self.image:free()
self.image = nil
end
end
return ImageWidget