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，即使我已将其定义为文件范围内的局部变量，timerId始终为nil。我是Lua开发的新手，所以我假设这个问题与变量范围有关，但是我很难找到一种方法来访问timer变量而不使它成为一个真正的全局变量（即声明它没有“local”关键字）。请参阅下面的代码段。

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

尝试取消这样：

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

Answer 2

我发现您发布的代码没有任何问题：当onPress被调用时，您的countdownTimer应该是非零的。你不应该测试countdownTimer是否为零。在创建新的按钮之前打印countdownTimer以确认它不是nil。同时搜索代码以查找引用变量的所有位置，并检查它们是否将其设置为nil。

更新：

您可以尝试的一件事是移动函数并使其成为本地函数：

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发现以上情况后仍无效）：

我看不出有什么不对，所以我在我的电晕模拟器中对此进行了测试，并且没有任何问题，因此问题出在其他地方。这是main.lua的全部内容：

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)

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

2 个答案: