在Corona sdk中显示图像

我使用 Corona SDK 制作了一个游戏。我试图在屏幕中央显示一张图片，但它会显示在随机位置。我想展示的图片是 circle.png。如果您能帮忙，请告诉我。

以下是代码：

local composer = require( "composer" )

local scene = composer.newScene()
local widget = require "widget"
widget.setTheme ("widget_theme_ios")

local score
local scoreEarn = 1

local lives = {}
local livesCount = 1

local balls = {}

local ballsCount = 0

local ballsSendSpeed = 65

local ballsTravelSpeed = 3500

local ballsIncrementSpeed = 1.5

local ballsMaxSendSpeed = 30

local timer_Counter

local onGameOver, gameOverBox, gameoverBackground, btn_returnToMenu

function scene:create( event )

    local sceneGroup = self.view

    local function ballTap(event)

    end

    local function ballDrag()

    end

    local function ballSend ()

    end

    local function ballsCollision ()

    end

    local function onCollision (event)

    end

    local function circleDamage ()

    end

    function gameOver ()

    end

    local background = display.newImageRect(sceneGroup, "images/gamescreen/background.png", 1600, 1200)
    background.x = _CX
    background.y = _CY

    local cirlce = display.newImageRect(sceneGroup, "images/gamescreen/circle.png", 184, 179)
    cirlce.x = _CX
    cirlce.y = _CY

end

function scene:show( event )

    local sceneGroup = self.view
    local phase = event.phase

    if ( phase == "will" ) then

    elseif ( phase == "did" ) then

    end

end

function scene:hide( event )

    local sceneGroup = self.view
    local phase = event.phase

    if ( phase == "will" ) then

    elseif ( phase == "did" ) then

    end

end

function scene:destroy( event )

    local sceneGroup = self.view

end

scene:addEventListener( "create", scene )
scene:addEventListener( "show", scene )
scene:addEventListener( "hide", scene )
scene:addEventListener( "destroy", scene )

return scene