koreader/frontend/ui/widget/overlapgroup.lua

local WidgetContainer = require("ui/widget/container/widgetcontainer")

--[[
A Layout widget that puts objects above each other
--]]
local OverlapGroup = WidgetContainer:new{
    _size = nil,
}

function OverlapGroup:getSize()
    if not self._size then
        self._size = {w = 0, h = 0}
        self._offsets = { x = math.huge, y = math.huge }
        for i, widget in ipairs(self) do
            local w_size = widget:getSize()
            if self._size.h < w_size.h then
                self._size.h = w_size.h
            end
            if self._size.w < w_size.w then
                self._size.w = w_size.w
            end
        end
    end

    if self.dimen.w then
        self._size.w = self.dimen.w
    end
    if self.dimen.h then
        self._size.h = self.dimen.h
    end

    return self._size
end

function OverlapGroup:paintTo(bb, x, y)
    local size = self:getSize()

    for i, wget in ipairs(self) do
        local wget_size = wget:getSize()
        if wget.align == "right" then
            wget:paintTo(bb, x+size.w-wget_size.w, y)
        elseif wget.align == "center" then
            wget:paintTo(bb, x+math.floor((size.w-wget_size.w)/2), y)
        else
            -- default to left
            wget:paintTo(bb, x, y)
        end
    end
end

return OverlapGroup