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https://github.com/koreader/koreader
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e47b43e8b5
This is a container that will honor a given alpha value (0..1) when painting, so it will be translucent for values < 1.
55 lines
1.8 KiB
Lua
55 lines
1.8 KiB
Lua
local WidgetContainer = require("ui/widget/container/widgetcontainer")
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local BlitBuffer = require("ffi/blitbuffer")
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--[[
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AlphaContainer will paint its content (1 widget) onto lower levels using
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a transparency (0..1)
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--]]
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local AlphaContainer = WidgetContainer:new{
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alpha = 1,
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-- we cache a blitbuffer object for re-use here:
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private_bb = nil,
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-- we save the underlying area here:
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background_bb = nil,
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background_bb_x = nil,
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background_bb_y = nil
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}
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function AlphaContainer:paintTo(bb, x, y)
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local contentSize = self[1]:getSize()
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local private_bb = self.private_bb
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if self.background_bb then
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-- we have a saved copy of what was below our paint area
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-- we restore this first
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bb:blitFrom(self.background_bb, self.background_bb_x, self.background_bb_y)
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end
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if not private_bb
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or private_bb:getWidth() ~= contentSize.w
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or private_bb:getHeight() ~= contentSize.h
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then
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-- create private blitbuffer for our child widget to paint to
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private_bb = BlitBuffer.new(contentSize.w, contentSize.h, bb:getType())
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self.private_bb = private_bb
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-- save what is below our painting area
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if not self.background_bb
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or self.background_bb:getWidth() ~= contentSize.w
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or self.background_bb:getHeight() ~= contentSize.h
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then
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self.background_bb = BlitBuffer.new(contentSize.w, contentSize.h, bb:getType())
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end
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self.background_bb:blitFrom(bb, 0, 0, x, y)
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end
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-- now have our childs paint to the private blitbuffer
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-- TODO: should we clean before painting?
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self[1]:paintTo(private_bb, 0, 0)
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-- blit the private blitbuffer to our parent blitbuffer
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bb:addblitFrom(private_bb, x, y, nil, nil, nil, nil, self.alpha)
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end
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return AlphaContainer
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