koreader/frontend/ui/widget/horizontalgroup.lua

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

--[[
A Layout widget that puts objects besides each others
--]]
local HorizontalGroup = WidgetContainer:new{
    align = "center",
    _size = nil,
}

function HorizontalGroup:getSize()
    if not self._size then
        self._size = { w = 0, h = 0 }
        self._offsets = { }
        for i, widget in ipairs(self) do
            local w_size = widget:getSize()
            self._offsets[i] = {
                x = self._size.w,
                y = w_size.h
            }
            self._size.w = self._size.w + w_size.w
            if w_size.h > self._size.h then
                self._size.h = w_size.h
            end
        end
    end
    return self._size
end

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

    for i, widget in ipairs(self) do
        if self.align == "center" then
            widget:paintTo(bb,
                x + self._offsets[i].x,
                y + math.floor((size.h - self._offsets[i].y) / 2))
        elseif self.align == "top" then
            widget:paintTo(bb, x + self._offsets[i].x, y)
        elseif self.align == "bottom" then
            widget:paintTo(bb, x + self._offsets[i].x, y + size.h - self._offsets[i].y)
        else
            io.stderr:write("[!] invalid alignment for HorizontalGroup: ",
                            self.align)
        end
    end
end

function HorizontalGroup:clear()
    self:free()
    WidgetContainer.clear(self)
end

function HorizontalGroup:resetLayout()
    self._size = nil
    self._offsets = {}
end

function HorizontalGroup:free()
    self:resetLayout()
    WidgetContainer.free(self)
end

return HorizontalGroup