View.onDraw（） - 当它被调用？ [英] View.onDraw() --- when does it get called?

问题描述

我把Log.d（）调用到我的扩展视图的OnDraw（），这样我就可以看多久，什么时候获取调用。它被调用时认为，这是不奇怪的实例。但后来我发现，它被要求由的onTouchEvent（处理每一个水龙头），即使我的code有没有做任何事情远程相关图形。然而，在意见文档，我似乎无法找到任何东西时的OnDraw（ ）实际被调用。我真的不关心我在这里特别项目（这不会导致我的一个问题），我只是想知道是否有什么地方列表或东西，显示操作的查看订单，特别是什么原因引起的的OnDraw（）来调用。

I put a Log.d() call into the onDraw() of my extended View, so I could see how often and when it's getting called. It gets called upon instantiation of the view, which is not surprising. But then I notice, it gets called on every tap that is handled by onTouchEvent(), even though my code there isn't doing anything remotely related to graphics. However, in the documentation for Views, I can't seem to find anything about when onDraw() is actually called. I'm not really concerned about my particular project here (this doesn't cause a problem for me), I would just like to know if there is a list somewhere or something that shows the order of operations for a View, particularly what causes onDraw() to get called.

推荐答案

AFAIK，视图的OnDraw（）被调用时：

AFAIK, a View's onDraw() is called when:

1. 在该视图最初绘制
2. 当<一href="http://developer.android.com/reference/android/view/View.html#invalidate%28%29">invalidate()被称为在视图

1. The view is initially drawn
2. Whenever invalidate() is called on the view

失效等可能由您或系统需要时调用。例如，很多意见而改变他们如何看onTouch，就像一个EditText得到一个轮廓和光标，或在pressed状态的按钮时。由于这一点，视图是重绘的联系。

Invalidate can be called by you or the system whenever needed. For example, a lot of Views change how they look onTouch, like an EditText getting an outline and cursor, or a button being in the pressed state. Due to this, Views are redrawn on touch.

我同意，这将是不错的一份文件，详细视图的工作，以及如果存在的话，有人知道在哪里可以找到它，请告诉我们。

I agree that it would be nice to have a document that detailed the working of Views, and if one exists and somebody knows where to find it, please let us know.

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