未指定事件名称的可绑定函数
在 Flex 中使函数 Bindable 而不指定事件名称会产生什么效果？我已经在我的代码中完成了此操作，并且它似乎工作正常，没有任何关联事件（但是它确实生成了警告）。如果我从此类函数中删除绑定，它确实会影响代码，并且如果函数的返回值发生更改，则不会反映更改。
有人可以解释一下，即使没有任何与 [Bindable] 标签关联的事件，这样的 Bindable 函数如何以及为什么工作。
示例：
<mx:Image id="a" source="{getImage(1)}" useHandCursor="true" buttonMode="true" width="10" height="10" click="finalize(event)" autoLoad="true"/>
[Bindable] private var _ratingSelected:int;
[Bindable]
private function getImage(value:int):String
{
if (value <= _ratingSelected)
return 'images/hr/applicants/star_icon.png';
else
return 'images/hr/applicants/star_icon_dis.png';
}
如果我从此处的 getImage 函数中删除 Bindable 标记，则图像在运行时不会正确更新。请注意，这里 _ ratingSelected 是可绑定变量。尽管我没有任何与 getImage() 函数相关的事件，但使其可绑定似乎工作得很好。它是否会自动检测 _ ratingSelected 变量（可绑定）的变化并在运行时调用 getImage 函数？请赐教。
谢谢。
What is the effect of making a function Bindable in flex without specifying event name with it? I have done this in my code and it seems to be working alright without any associated event (however it does generate a warning). If I remove the binding from such functions it will does effect the code and doesnt reflect the changes if the return value from the function changes.
Could someone explain me , how and why such Bindable function work even without any event associated with [Bindable] tag.
Example:
<mx:Image id="a" source="{getImage(1)}" useHandCursor="true" buttonMode="true" width="10" height="10" click="finalize(event)" autoLoad="true"/>
[Bindable] private var _ratingSelected:int;
[Bindable]
private function getImage(value:int):String
{
if (value <= _ratingSelected)
return 'images/hr/applicants/star_icon.png';
else
return 'images/hr/applicants/star_icon_dis.png';
}
If I remove the Bindable tag from getImage function here, the image doesnt properly get updated at the run time. Please note that _ratingSelected is Bindable variable here. Even though I don't have any event associated with getImage() function, making it Bindable seems to be working just alright. Does it automatically detect changes to changes in _ratingSelected variable (which is bindable) and call the getImage function at run time? Kindly enlighten.
Thanks.
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当您未在 Binding 标记中指定事件名称时，它将使用事件“propertyChange”。这意味着每次框架从文档中获取“propertyChange”事件时，它都会尝试通过再次调用
getImage来更新图像源。现在，当
_ ratingSelected的值更新时，会在内部调度“propertyChange”事件，从而导致图像更新。请注意，这与
getImage是否实际使用_atingSelected生成其返回值无关。从数据绑定框架的角度来看，getImage和_atingSelected之间的唯一联系是“propertyChange”事件，它们都声称在各自的值发生更改时调度该事件（即使getImage从未实际调度它）。When you don't specify an event name in the Binding tag, it uses the event "propertyChange". This means that every time the framework gets a "propertyChange" event from your document, it'll try to update the image source by calling
getImageagain.Now when the value of
_ratingSelectedis updated, a "propertyChange" event is dispatched internally, which then causes the image to be updated.Note that this has nothing to do with whether
getImageactually uses_ratingSelectedto generate its return value. The only connection betweengetImageand_ratingSelectedfrom the data binding framework's point of view is the "propertyChange" event which they both claim to dispatch when their respective values have changed (even thoughgetImagenever actually dispatches it).