koreader/frontend/ui/widget/container/centercontainer.lua

--[[--
CenterContainer centers its content (1 widget) within its own dimensions
--]]

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

local CenterContainer = WidgetContainer:extend{}

function CenterContainer:paintTo(bb, x, y)
    local content_size = self[1]:getSize()

    -- check if content is bigger than container
    if self.ignore_if_over == "height" then -- align upper borders
        if self.dimen.h < content_size.h then
            self.ignore = "height"
        end
    elseif self.ignore_if_over == "width" then -- align left borders
        if self.dimen.w < content_size.w then
            self.ignore = "width"
        end
    end

    local x_pos = x
    local y_pos = y
    if self.ignore ~= "height" then
        y_pos = y + math.floor((self.dimen.h - content_size.h)/2)
    end
    if self.ignore ~= "width" then
        x_pos = x + math.floor((self.dimen.w - content_size.w)/2)
    end
    self[1]:paintTo(bb, x_pos, y_pos)
end

return CenterContainer