显示对象（按钮小部件）在添加到情节提要显示组时不显示答案

【问题标题】：Display objects (button widgets) aren't shown when they are added to the storyboard display group显示对象（按钮小部件）在添加到情节提要显示组时不显示
【发布时间】：2014-04-25 09:53:25
【问题描述】：

我有一个简单的场景。共有三个按钮小部件和一个标题。

当我将它们包含到group 中时，不会绘制对象。但是，当我不包括它们时，它们就会出现。但退出场景后它们不会消失。

我一直在阅读有关故事板模块的信息，并且我确信通过将它们加入到组中，我以正确的方式使用它。

为什么显示对象包含在组中时不绘制？

我将包含我的 main.lua，以防万一。

main.lua:

local storyboard = require("storyboard")
local mydata = require("mydata")

local widget = require( "widget" )

centerX = display.contentCenterX
centerY = display.contentCenterY
_W = display.contentWidth
_H = display.contentHeight

display.setStatusBar( display.HiddenStatusBar )

local bkg = display.newImage( "stripes.png", centerX, centerY )

local disclaimer = display.newText("DISCLAIMER", 300-75, centerY-175, 320, 0, "Helvetica", 30 )

local message = display.newText("The creators take no responsibility for\nany damage done by this app, etc.\n", 300-110, centerY-120, 320, 0, "Helvetica", 16)


local howtoTitle = display.newText("HOW TO PLAY", 300-85, centerY-50,320, 0, "Helvetica", 30)
local howto = display.newText("1. Select Time Frame\n      2.Select Sides\n       3.Have Fun", 300-60, centerY, 320, 0, "Helvetica", 16)

mydata.time = 0
mydata.sides = 0
mydata.hits = 0

-- Function to handle button events
local function handleButtonEvent( event )
    local phase = event.phase
    if "ended" == phase then
        event.target:removeSelf()
        disclaimer:removeSelf()
        message:removeSelf()
        howto:removeSelf()
        howtoTitle:removeSelf()
        storyboard.loadScene("time_select")
    end
end

local playButton = widget.newButton {
    left = 100,
    top = 350,
    width = 105,
    height = 39,
    defaultFile = "start.png",
    overFile = "start_pressed.png",
    label = "",
    onEvent = handleButtonEvent,
}

time_select.lua：

local storyboard = require("storyboard")
local widget = require("widget")

local scene = storyboard.newScene()

local mydata = require("mydata")

local function fifteenSecondButtonEvent( event )
    local phase = event.phase
    if "ended" == phase then
        mydata.time = 15
        storyboard.gotoScene("play")
    end
end

local function thirtySecondButtonEvent( event )
    local phase = event.phase
    if "ended" == phase then
        mydata.time = 30
        storyboard.gotoScene("play")
    end
end

local function sixtySecondButtonEvent( event )
    local phase = event.phase
    if "ended" == phase then
        mydata.time = 60
        storyboard.gotoScene("play")
    end
end



function scene:createScene( event )
    local group = self.view
    local timeText = display.newText("TIME", 160, 70, "Helvetica", 30)
    group:insert( timeText )

    local fifteenButton = widget.newButton {
        time = 15,
        left = 75,
        top = 150,
        width = 164,
        height = 42,
        defaultFile = "fifteen_button.png",
        overFile = "fifteen_button_pressed.png",
        label = "",
        onRelease = fifteenSecondButtonEvent
    }
    group:insert(fifteenButton)

    local thirtyButton = widget.newButton {
        time = 30,
        left = 75,
        top = 250,
        width = 164,
        height = 42,
        defaultFile = "thirty_button.png",
        overFile = "thirty_button_pressed.png",
        label = "",
        onRelease = thirtySecondButtonEvent
    }
    group:insert(thirtyButton)

    local sixtyButton = widget.newButton {
        time = 60,
        left = 75,
        top = 350,
        width = 164,
        height = 42,
        defaultFile = "sixty_button.png",
        overFile = "sixty_button_pressed.png",
        label = "",
        onRelease = sixtySecondButtonEvent
    }
    group:insert(sixtyButton)
    print( "Number of children in Display Group: " .. group.numChildren )
end

function scene:willEnterScene( event )
    local group = self.view
end

function scene:enterScene( event )
    local group = self.view
end

function scene:exitScene( event )
    local group = self.view
    fifteenButton:removeEventListener( 'onRelease', fifteenSecondButtonEvent ) -- line 92
    thirtyButton:removeEventListener( 'onRelease', thirtySecondButtonEvent )
    sixtyButton:removeEventListener( 'onRelease', sixtySecondButtonEvent )

    timeText:removeSelf()
    timeText = nil
    if fifteenButton then
        fifteenButton:removeSelf()
        fifteenButton = nil
    end

    if thirtyButton then
        thirtyButton:removeSelf()
        thirtyButton = nil
    end

    if sixtyButton then
        sixtyButton:removeSelf()
        sixtyButton = nil
    end

    display.remove(group)
    storyboard.removeScene( "time_select" )

end

function scene:destroyScene( event )
    local group = self.view
end

scene:addEventListener("createScene", scene)
scene:addEventListener("willEnterScene", scene)
scene:addEventListener("enterScene", scene)
scene:addEventListener("exitScene", scene)
scene:addEventListener("destroyScene", scene)

return scene

【问题讨论】：

标签： mobile lua storyboard coronasdk

【解决方案1】：

这是因为您使用的是storyboard.loadScene("time_select")。这会加载场景但不会显示它，因此您看不到添加到其视图组中的对象。当您不将对象添加到视图组时，它们会显示出来，因为默认情况下，对象会放在默认的“根级别”组中，称为 stage。来自Group Programming Guide的绘图模型部分：

未放入特定组的显示对象成为舞台的一部分

改用storyboard.gotoScene("time_select")，以便您的应用转换到另一个场景（除非您打算将time_select 用作叠加层，否则请使用storyboard.showOverlay）。

更新：看起来有两个问题，正如您自己的回答所证明的那样。我将您的固定代码复制到我的模拟器并执行它，果然，loadScene() 我什么都看不到；我不得不使用gotoScene()。

但是，您的回答中有几处不正确：

main.lua 可以创建第一个场景：scene = storbyboard.newScene("scene1") 然后storyboard.gotoScene("uniqueName") 和所有场景1 事件处理程序（createScene 等）都可以在 main.lua 中。
您可以将侦听器函数放置在您想要的任何位置。
当对象调用 removeSelf 时，在对象上注册的侦听器会自动取消注册。运行时不是显示对象，因此对于像“enterFrame”这样的运行时侦听器，您必须在退出场景时显式删除事件处理程序。
您不需要在destroyScene 中添加removeSelf 对象，因为当scene.view 被删除时，这会自动为您完成（在调用destroyScene 后自动完成）。
你不应该在time_select.exitScene 中调用removeScene('time_select')，这没有任何意义！ exit 中的 removeScene 将导致从 exitScene 调用 destroyScene！如果您知道不再需要 time_select 场景，则可以将其从（例如）主场景的 enterScene 中删除。这将调用 time_select 的destroyScene，并删除scene.view 组。后者将递归删除组中的每个对象（这将取消注册这些对象的侦听器）。

这两点演示如下：我将handleButtonEvent 移出createScene。

main.lua:

local storyboard = require "storyboard"
local widget = require "widget"

local scene = storyboard.newScene("scene1")

local mydata = {} -- require("mydata")
local widget = require( "widget" )

local centerX = display.contentCenterX
local centerY = display.contentCenterY
local _W = display.contentWidth
local _H = display.contentHeight

mydata.time = 0
mydata.sides = 0
mydata.hits = 0

local function handleButtonEvent( event )
    if "ended" == event.phase then
        storyboard.gotoScene("time_select", "fade", 500)
    end
    return true
end

function scene:createScene( event )
    local group = self.view
    local background = display.newImage( "stripes.png", centerX, centerY )
    background.anchorX, background.anchorY = 0.0,0.0
    background.x, background.y = 0, 0
    group:insert( background )

    local disclaimer = display.newText("DISCLAIMER", 300-75, centerY-175, 320, 0, "Helvetica", 30 )
    group:insert( disclaimer )
    local message = display.newText("The creators take no responsibility for\nany damage done by this app, etc.\n", 300-110, centerY-120, 320, 0, "Helvetica", 16)
    group:insert( message )
    local howtoTitle = display.newText("HOW TO PLAY", 300-85, centerY-50,320, 0, "Helvetica", 30)
    group:insert( howtoTitle )
    local howto = display.newText("1. Select Time Frame\n      2.Select Sides\n       3.Have Fun", 300-60, centerY, 320, 0, "Helvetica", 16)
    group:insert( howto )

    local playButton = widget.newButton {
        left = 100,
        top = 350,
        width = 105,
        height = 39,
        label = "Play",
        onEvent = handleButtonEvent,
    }
    playButton.isActive = true
    group:insert(playButton)
end

function scene:enterScene( event )
    local group = self.view
end

function scene:exitScene( event )
    local group = self.view
end

function scene:destroyScene( event )
    local group = self.view
end

scene:addEventListener( "createScene", scene )
scene:addEventListener( "enterScene", scene )
scene:addEventListener( "exitScene", scene )
scene:addEventListener( "destroyScene", scene )

-- load first scene
storyboard.gotoScene( "scene1", "fade", 400 )

time_select.lua`：

local storyboard = require("storyboard")
local widget = require("widget")

local scene = storyboard.newScene()

local mydata = {} -- require("mydata")

local function fifteenSecondButtonEvent( event )
    local phase = event.phase
    if "ended" == phase then
        mydata.time = 15
        storyboard.gotoScene("play")
    end
end

local function thirtySecondButtonEvent( event )
    local phase = event.phase
    if "ended" == phase then
        mydata.time = 30
        storyboard.gotoScene("play")
    end
end

local function sixtySecondButtonEvent( event )
    local phase = event.phase
    if "ended" == phase then
        mydata.time = 60
        storyboard.gotoScene("play")
    end
end

function scene:createScene( event )
    local group = self.view
    local timeText = display.newText("TIME", 160, 70, "Helvetica", 30)
    group:insert( timeText )

    local fifteenButton = widget.newButton {
        time = 15,
        left = 75,
        top = 150,
        width = 164,
        height = 42,
        label = "15 Button",
        onRelease = fifteenSecondButtonEvent
    }
    group:insert(fifteenButton)

    local thirtyButton = widget.newButton {
        time = 30,
        left = 75,
        top = 250,
        width = 164,
        height = 42,
        label = "30 Button",
        onRelease = thirtySecondButtonEvent
    }
    group:insert(thirtyButton)

    local sixtyButton = widget.newButton {
        time = 60,
        left = 75,
        top = 350,
        width = 164,
        height = 42,
        label = "45 Button",
        onRelease = sixtySecondButtonEvent
    }
    group:insert(sixtyButton)
    print( "Number of children in Display Group: " .. group.numChildren )
end

function scene:willEnterScene( event )
    local group = self.view
end

local demoNonObjListenerCount
local function enterFrame(event)
    demoNonObjListenerCount = demoNonObjListenerCount + 1 
end

function scene:enterScene( event )
    local group = self.view

    Runtime:addEventListener('enterFrame', enterFrame)
end

function scene:exitScene( event )
    local group = self.view

    Runtime:removeEventListener('enterFrame', enterFrame)    
end

function scene:destroyScene( event )
    local group = self.view
    -- self.view will be removed upon return, which will 
    -- remove display objects contained, recursively, so 
    -- here not much else to do
end

scene:addEventListener("createScene", scene)
scene:addEventListener("willEnterScene", scene)
scene:addEventListener("enterScene", scene)
scene:addEventListener("exitScene", scene)
scene:addEventListener("destroyScene", scene)

return scene

time_select.lua 的内容甚至可以放在main.lua 中，如果您将每次出现的“场景”替换为“timeSelect”并使用timeSelect = storyboard.newScene("time_select")。但是，模块化更好，所以最好将time_select 场景保留在自己的文件中，但scene1 不必与main.lua 在单独的文件中。

【讨论】：

你的解释很有道理。我在 main.lua 中将loadScene 换成了gotoScene，但它仍然拒绝出现。我尝试了我找到的其他故事板示例，它们都不起作用，我觉得它可能是我的构建版本（2013.2100）
@EjayTumacder 如果没有一个示例适用于您安装的 2100，那么所有的赌注都没有了，但是我相信一旦您找到了适用于开箱即用的 Corona 版本例如，您将不得不按照上述更改您的代码。请注意，2100 是我使用的稳定版本，我会尝试卸载并重新安装。还有你所说的“不工作”是什么意思？
对不起，我应该详细说明“不工作”。他们似乎都给了我空白屏幕。我使用了这个github.com/RevMob/corona-sample-with-storyboard 和附加到这个develephant.net/… 的代码，仅举几例。它们似乎都不起作用
打开 Corona 模拟器后，您会在右侧看到“Docs Samples Forum Learn”吗？从“入门”组中选择一个示例。他们的样本是否运行？
我找到了解决方案，原因似乎是您发布的答案的一部分。我认为我的构建没有任何问题。我想我只是很沮丧:)

【解决方案2】：

好的，所以我找到了一个适用于我的构建 (2013.2100) 的示例情节提要，并尝试使用它来找到我的问题。这是我在 main.lua 文件中绘制显示对象的事实。 main.lua 的唯一目的似乎是引导您进入第一个场景，这似乎是惯例。我将前两个文件分成三个单独的文件，一切都按照预期的方式运行。

我相信原因也是@Schollii 回答的一部分：

未放入特定组的显示对象成为舞台的一部分

background是舞台的一部分，所以当它切换到下一个场景时，它被舞台上的展示物体所覆盖。

@user3439409 我听说您必须将侦听器函数放在 createScene 中，就像我在下面的代码中那样。至于 addEventListener、removeEventListener 等。您不需要执行 addEventListener，因为 widget 会为您执行此操作。但是，我听说您应该删除事件侦听器，因为它会留在内存中。您可以通过添加有关内存的打印语句来检查内存泄漏。为此，您可以使用storyboard.printMemUsage()

main.lua（现在只有 3 行）：

display.setStatusBar( display.HiddenStatusBar )

local storyboard = require("storyboard")

storyboard.gotoScene( "start", "fade", 500 )

start.lua（我的 main.lua 之前的）：

local storyboard = require( "storyboard")
local scene = storyboard.newScene()

mydata = require("mydata")
widget = require( "widget" )

centerX = display.contentCenterX
centerY = display.contentCenterY
_W = display.contentWidth
_H = display.contentHeight

mydata.time = 0
mydata.sides = 0
mydata.hits = 0

function scene:createScene( event )
    local group = self.view
    local background = display.newImage( "stripes.png", centerX, centerY )
    background.anchorX, background.anchorY = 0.0,0.0
    background.x, background.y = 0, 0
    group:insert( background )

    local disclaimer = display.newText("DISCLAIMER", 300-75, centerY-175, 320, 0, "Helvetica", 30 )
    group:insert( disclaimer )
    local message = display.newText("The creators take no responsibility for\nany damage done by this app, etc.\n", 300-110, centerY-120, 320, 0, "Helvetica", 16)
    group:insert( message )
    local howtoTitle = display.newText("HOW TO PLAY", 300-85, centerY-50,320, 0, "Helvetica", 30)
    group:insert( howtoTitle )
    local howto = display.newText("1. Select Time Frame\n      2.Select Sides\n       3.Have Fun", 300-60, centerY, 320, 0, "Helvetica", 16)
    group:insert( howto )

    local playButton = nil
    local function handleButtonEvent( event )
        if "ended" == event.phase then
            storyboard.gotoScene("time_select", "fade", 500)
        end
        return true
    end
    playButton = widget.newButton {
        left = 100,
        top = 350,
        width = 105,
        height = 39,
        defaultFile = "start.png",
        overFile = "start_pressed.png",
        label = "",
        onEvent = handleButtonEvent,
    }
    playButton.isActive = true
    group:insert(playButton)
end

function scene:enterScene( event )
    local group = self.view
end

function scene:exitScene( event )
    local group = self.view
end

function scene:destroyScene( event )
    local group = self.view
end

-- Function to handle button events


scene:addEventListener( "createScene", scene )
scene:addEventListener( "enterScene", scene )
scene:addEventListener( "exitScene", scene )
scene:addEventListener( "destroyScene", scene )

return scene

time_select.lua（我将监听函数放在 createScene 中）：

local storyboard = require("storyboard")

local scene = storyboard.newScene()

 local widget = require "widget"

function scene:createScene( event )
    local group = self.view
    --local background = display.newImage("stripes.png", centerX, centerY)
    --group:insert(backgroundz)

    local background = display.newImage( "stripes.png", centerX, centerY )
    background.anchorX, background.anchorY = 0.0,0.0
    background.x, background.y = 0, 0
    group:insert( background )

    local timeText = display.newText("TIME", 0, 0, "Helvetica", 30)
    timeText.x = _W/2
    timeText.y = _H/2 - 150
    timeText:setFillColor( 255, 255, 255 )
    group:insert(timeText)

    local fifteenButton = nil
    local function fifteenSecondButtonEvent( event )
        if "ended" == event.phase then
            mydata.time = 15
            storyboard.gotoScene("sides_selection")
        end
        return true
    end
    fifteenButton = widget.newButton {
        left = 75,
        top = 150,
        width = 164,
        height = 42,
        defaultFile = "fifteen_button.png",
        overFile = "fifteen_button_pressed.png",
        label = "",
        onRelease = fifteenSecondButtonEvent
    }
    fifteenButton.isActive = true
    group:insert(fifteenButton)

    local thirtyButton = nil
    local function thirtySecondButtonEvent( event )
        local phase = event.phase
        if "ended" == phase then
            mydata.time = 30
            storyboard.gotoScene("play")
        end
    end
    thirtyButton = widget.newButton {
        left = 75,
        top = 250,
        width = 164,
        height = 42,
        defaultFile = "thirty_button.png",
        overFile = "thirty_button_pressed.png",
        label = "",
        onRelease = thirtySecondButtonEvent
    }
    thirtyButton.active = true
    group:insert(thirtyButton)

    local sixtySecondButtonEvent = nil
    local function sixtySecondButtonEvent( event )
        local phase = event.phase
        if "ended" == phase then
            mydata.time = 60
            storyboard.gotoScene("play")
        end
    end
    sixtyButton = widget.newButton {
        left = 75,
        top = 350,
        width = 164,
        height = 42,
        defaultFile = "sixty_button.png",
        overFile = "sixty_button_pressed.png",
        label = "",
        onRelease = sixtySecondButtonEvent
    }
    group:insert(sixtyButton)
end

function scene:enterScene( event )
    local group = self.view
end

function scene:exitScene( event )
    local group = self.view
end

function scene:destroyScene( event )
    local group = self.view
end

scene:addEventListener("createScene", scene)
scene:addEventListener("enterScene", scene)
scene:addEventListener("exitScene", scene)
scene:addEventListener("destroyScene", scene)

return scene

【讨论】：

+1 表示答案的第二部分。内部不需要监听器，也不需要将第一个场景放在单独的文件中，只有运行时监听器需要显式删除。所以我扩展了我的回答来讨论这些观点，因为它们可能会误导 Corona 的其他新手用户。
感谢您的智慧和指导。拿起 Corona + Lua 很艰难。

【解决方案3】：

如果您使用故事板，则需要调用 storyboard.removeScene() 方法从显示组中删除所有对象。这是参考。 http://docs.coronalabs.com/api/library/storyboard/removeScene.html http://docs.coronalabs.com/api/library/storyboard/

【讨论】：