Corona SDK - 从 Widget Candy 按钮 onPress 处理程序中取消计时器

Question

我正在尝试取消 Widget Candy 按钮的 onPress 事件处理程序中的计时器。但是，即使我已将 timerId 定义为文件范围内的局部变量，timerId 也始终为零。我是 Lua 开发的新手，所以我假设这个问题与变量范围有关，但我很难找到一种方法来访问计时器变量而不使其成为真正的全局变量（即在没有“local”关键字的情况下声明它)。见下面的代码sn-p。

local countdownTimer = timer.performWithDelay(1000, handleCountdownTimer, countdown);

local answerButton1 = wcandy.NewButton
{
x       = "center",
y       = "55%",
width   = "75%",
name    = "MyButton1",
theme   = "theme_1",
border     = {"normal",6,1, .12,.12,0,.4,  .72,.72,.72,.6},
pressColor = {1,1,1,.25},
caption = "Touch me!",
textAlign   = "center",
fontSize    = "40",
onPress     =   function( EventData )
                    timer.cancel(countdownTimer); -- "countdownTimer" is always nil!!!
                    local button = wcandy.GetHandle("MyButton1");
                    if button:get("caption") == tostring(solution) then
                        questionText:set("caption", "Correct!");
                    else
                        questionText:set("caption", "Wrong!");
                    end
                end
}

Answer 1

我认为您发布的代码没有任何问题：当 onPress 被调用时，您的 countdownTimer 应该不为零。您不必测试 countdownTimer 是否为零。在创建新按钮之前打印 countdownTimer 以确认它不为零。还可以搜索代码以查找引用该变量的所有位置，并检查是否有任何位置将其设置为 nil。

更新：

您可以尝试的一件事是移动函数并将其设为本地：

local countdownTimer = timer.performWithDelay(1000, handleCountdownTimer, countdown);

local function cancelTimer( EventData )
    timer.cancel(countdownTimer); -- "countdownTimer" is always nil!!!
    local button = wcandy.GetHandle("MyButton1");
    if button:get("caption") == tostring(solution) then
        questionText:set("caption", "Correct!");
    else
        questionText:set("caption", "Wrong!");
    end
end

local answerButton1 = wcandy.NewButton
{
x       = "center",
y       = "55%",
width   = "75%",
name    = "MyButton1",
theme   = "theme_1",
border     = {"normal",6,1, .12,.12,0,.4,  .72,.72,.72,.6},
pressColor = {1,1,1,.25},
caption = "Touch me!",
textAlign   = "center",
fontSize    = "40",
onPress     = cancelTimer
}

更新 2（在@husterk 发现上述内容仍然不起作用之后）：

我看不出有什么问题，所以我在我的 corona sim 中对此进行了测试，没有问题，所以问题出在其他地方。这是 main.lua 的完整内容：

local widget = require('widget')

local function handleCountdownTimer(event)
    print('timed out; timer:', event.source)
end

local countdownTimer

local function cancelTimer( event )
    print('cancelling timout, timer:', countdownTimer)
    timer.cancel(countdownTimer) 
end

local answerButton1 = widget.newButton
{
    onPress     = cancelTimer, 
    width = 100,
    height = 100,
    label = 'hello',
    emboss = true
}

countdownTimer = timer.performWithDelay(10000, handleCountdownTimer)
print('timer started:', countdownTimer)

Answer 2

尝试像这样取消：

if(countdownTimer~=nil)  -- Check whether timer is triggering or not 
  timer.cancel(countdownTimer)
end