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https://github.com/koreader/koreader
synced 2024-11-10 01:10:34 +00:00
0c80537003
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).
134 lines
3.7 KiB
Lua
134 lines
3.7 KiB
Lua
local Widget = require("ui/widget/widget")
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local Screen = require("device").screen
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local CacheItem = require("cacheitem")
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local Mupdf = require("ffi/mupdf")
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local Geom = require("ui/geometry")
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local Cache = require("cache")
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local DEBUG = require("dbg")
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local ImageCache = Cache:new{
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max_memsize = 2*1024*1024, -- 2M of image cache
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current_memsize = 0,
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cache = {},
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-- this will hold the LRU order of the cache
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cache_order = {}
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}
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local ImageCacheItem = CacheItem:new{}
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function ImageCacheItem:onFree()
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if self.bb.free then
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DEBUG("free image blitbuffer", self.bb)
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self.bb:free()
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end
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end
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--[[
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ImageWidget shows an image from a file
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--]]
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local ImageWidget = Widget:new{
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file = nil,
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image = nil,
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invert = nil,
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dim = nil,
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hide = nil,
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-- if width or height is given, image will rescale to the given size
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width = nil,
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height = nil,
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-- if autoscale is true image will be rescaled according to screen dpi
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autoscale = false,
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-- when alpha is set to true, alpha values from the image will be honored
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alpha = false,
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_bb = nil
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}
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function ImageWidget:_loadimage()
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self._bb = self.image
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end
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function ImageWidget:_loadfile()
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local itype = string.lower(string.match(self.file, ".+%.([^.]+)") or "")
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if itype == "png" or itype == "jpg" or itype == "jpeg"
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or itype == "tiff" then
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local hash = "image|"..self.file.."|"..(self.width or "").."|"..(self.height or "")
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local cache = ImageCache:check(hash)
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if cache then
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-- hit cache
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self._bb = cache.bb
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else
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-- cache this image
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DEBUG("cache", hash)
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local cache = ImageCacheItem:new{
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bb = Mupdf.renderImageFile(self.file, self.width, self.height),
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}
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cache.size = cache.bb.pitch * cache.bb.h * cache.bb:getBpp() / 8
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ImageCache:insert(hash, cache)
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self._bb = cache.bb
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end
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else
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error("Image file type not supported.")
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end
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end
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function ImageWidget:_render()
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if self.image then
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self:_loadimage()
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elseif self.file then
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self:_loadfile()
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else
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error("cannot render image")
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end
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local native_w, native_h = self._bb:getWidth(), self._bb:getHeight()
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local scaled_w, scaled_h = self.width, self.height
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if self.autoscale then
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local dpi_scale = Screen:getDPI() / 167
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-- rounding off to power of 2 to avoid alias with pow(2, floor(log(x)/log(2))
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local scale = math.pow(2, math.max(0, math.floor(math.log(dpi_scale)/0.69)))
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scaled_w, scaled_h = scale * native_w, scale * native_h
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end
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if (scaled_w and scaled_w ~= native_w) or (scaled_h and scaled_h ~= native_h) then
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self._bb = self._bb:scale(scaled_w or native_w, scaled_h or native_h)
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end
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end
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function ImageWidget:getSize()
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self:_render()
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return Geom:new{ w = self._bb:getWidth(), h = self._bb:getHeight() }
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end
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function ImageWidget:rotate(degree)
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self:_render()
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self._bb:rotate(degree)
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end
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function ImageWidget:paintTo(bb, x, y)
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if self.hide then return end
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-- self:_reader is called in getSize method
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local size = self:getSize()
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self.dimen = Geom:new{
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x = x, y = y,
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w = size.w,
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h = size.h
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}
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if self.alpha == true then
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bb:alphablitFrom(self._bb, x, y, 0, 0, size.w, size.h)
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else
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bb:blitFrom(self._bb, x, y, 0, 0, size.w, size.h)
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end
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if self.invert then
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bb:invertRect(x, y, size.w, size.h)
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end
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if self.dim then
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bb:dimRect(x, y, size.w, size.h)
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end
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end
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function ImageWidget:free()
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if self.image then
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self.image:free()
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self.image = nil
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end
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end
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return ImageWidget
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