koreader/frontend/apps/reader/modules/readerrotation.lua

local InputContainer = require("ui/widget/container/inputcontainer")
local Screen = require("ui/screen")
local Geom = require("ui/geometry")
local Device = require("ui/device")
local Event = require("ui/event")
local GestureRange = require("ui/gesturerange")
local _ = require("gettext")

local ReaderRotation = InputContainer:new{
    ROTATE_ANGLE_THRESHOLD = 15,
    current_rotation = 0
}

function ReaderRotation:init()
    if Device:hasKeyboard() then
        self.key_events = {
            -- these will all generate the same event, just with different arguments
            RotateLeft = {
                {"J"},
                doc = "rotate left by 90 degrees",
                event = "Rotate", args = -90 },
            RotateRight = {
                {"K"},
                doc = "rotate right by 90 degrees",
                event = "Rotate", args = 90 },
        }
    end
    if Device:isTouchDevice() then
        self.ges_events = {
            RotateGes = {
                GestureRange:new{
                    ges = "rotate",
                    range = Geom:new{
                        x = 0, y = 0,
                        w = Screen:getWidth(),
                        h = Screen:getHeight(),
                    },
                    rate = 0.3
                }
            },
        }
    end
end

-- TODO: reset rotation on new document, maybe on new page?

function ReaderRotation:onRotate(rotate_by)
    self.current_rotation = (self.current_rotation + rotate_by) % 360
    self.ui:handleEvent(Event:new("RotationUpdate", self.current_rotation))
    return true
end

function ReaderRotation:onRotateGes(arg, ges)
    if ges.angle and ges.angle > self.ROTATE_ANGLE_THRESHOLD then
        if Screen:getScreenMode() == "portrait" then
            self.ui:handleEvent(Event:new("SetScreenMode", "landscape"))
        else
            self.ui:handleEvent(Event:new("SetScreenMode", "portrait"))
        end
    end
    return true
end

return ReaderRotation