Button Class

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-- Button class
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function newButton( params )
    local src, width, height, align, unBounded
    local unit = 32

    if not params.src then
        -- No filename supplied
        return false
    else
        src = params.src
    end

    width = params.width
    height = params.height
        unBounded = params.unBounded

    local spriteSheet = sprite.newSpriteSheet(src, width, height)
    local spriteSet = sprite.newSpriteSet(spriteSheet, 1, spriteSheet.frameCount)
    local button = sprite.newSprite(spriteSet)

    if params.x then
        button.x = params.x
    end
    if params.y then
        button.y = params.y
    end

    if params.onPress and type(params.onPress) == 'function' then
        button._onPress = params.onPress
    end
    if params.onRelease and type(params.onRelease) == 'function' then
        button._onRelease = params.onRelease
    end
    if params.onMove and type(params.onMove) == 'function' then
        button._onMove = params.onMove
    end
    if params.onCancel and type(params.onCancel) == 'function' then
        button._onCancel = params.onCancel
    end
    if params.onInactive and type(params.onInactive) == 'function' then
        button._onInactive = params.onInactive
    end

    -- set button to active (meaning, can be pushed)
    button.isActive = true

    -- If it's a switch, state 0 is off, 1 - on.
    button.state = 0
    local default, pressed, inactive
    if params.switch then
        button.isSwitch = true
        default, pressed, inactive = 1, 3, 5
    else
        default, pressed, inactive = 1, 2, 3
    end

    function button:touch (event)
        local result = true
        if self.isActive then
            local onPress = self._onPress
            local onMove = self._onMove
            local onRelease = self._onRelease
            local onCancel = self._onCancel

            local phase = event.phase
            if phase == 'began' then
                self.currentFrame = pressed + self.state
                if onPress then
                    result = onPress(event)
                end
                -- Subsequent touch events will target button even if they are outside the stageBounds of button
                display.getCurrentStage():setFocus(self, event.id)
                self.isFocus = true
            elseif self.isFocus then
                local bounds = self.contentBounds
                local x, y = event.x,event.y
                local isWithinBounds = bounds.xMin <= x and bounds.xMax >= x and bounds.yMin <= y and bounds.yMax >= y

                if phase == 'moved' then
                    if isWithinBounds or unBounded then
                        -- The rollover image should only be visible while the finger is within button's stageBounds
                        self.currentFrame = pressed + self.state
                    else
                        self.currentFrame = default + self.state
                    end
                    if onMove then
                        result = onMove(event)
                    end
                elseif phase == 'ended' or phase == 'cancelled' then
                    self.currentFrame = default + self.state
                    if phase == 'ended' then
                        -- Only consider this a "click" if the user lifts their finger inside button's stageBounds
                        if isWithinBounds or unBounded then
                            if onRelease then
                                if self.isSwitch then
                                    self:toggle()
                                end
                                result = onRelease(event)
                            end
                        end
                    elseif phase == 'cancelled' then
                        if onCancel then
                            result = onCancel(event)
                        end
                    end
                    -- Allow touch events to be sent normally to the objects they "hit"
                    display.getCurrentStage():setFocus(self, nil)
                    self.isFocus = false
                end
            end
        else
            if self._onInactive and event.phase == 'began' then
                result = self._onInactive(event)
            end
        end
        return result
    end

    button:addEventListener('touch', button)

    function button:disable ()
        self.currentFrame = inactive
        self.isActive = false
    end

    function button:enable ()
        self.currentFrame = default + self.state
        self.isActive = true
    end

    function button:toggle ()
        if self.state == 1 then
            self.currentFrame = self.currentFrame - 1
            self.state = 0
        else
            self.currentFrame = self.currentFrame + 1
            self.state = 1
        end
    end

    return button
end