View 翻译

http://developer.android.com/intl/zh-CN/reference/android/view/View.html

类概述（Class Overview）

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这个类表示用户界面组件的基本构建块。视图占据了屏幕上的一个矩形区域，并负责绘图和事件处理。View是基类的部件，这是用来创建交互式UI组件（按钮，文本框等）。ViewGroup子类是基类的布局，这是invisible的容器，用来装别的View或ViewGroup，并定义它们的布局属性。

开发指南

如需使用这个类来开发应用程序的用户界面的信息，阅读的用户界面开发指南。

使用视图

所有的View，在一个窗口中排列像“一棵树”。您可以添加代码或通过指定树中的一个或多个XML布局文件。有许多专门的子类的View

，作为控制或能够显示文字，图像或其他内容。（树： 在对界面进行布局是就像一颗树。从根元素开始布局。）

一旦你已经创建了一个树的View，一般有几类常见的操作，你不妨来执行：

• Set properties:：例如设置一个文本TextView。可用的属性和设置的方法，他们将各不相同意见不同的子类。请注意，在编译时已知的属性可以设置在XML布局文件。
• 设置焦点（Set focus）：框架将处理移动响应用户输入的焦点。要强制焦点到一个特定的视图，调用requestFocus（）。
• Set up listeners:：Views allow clients to set listeners that will be notified when something interesting happens to the view。例如，所有的View，将让你设置一个监听的观点获得或失去焦点时通知。您可以寄存器使用setOnFocusChangeListener（android.view.View.OnFocusChangeListener）这样一个监听器 。其他视图子类提供更专业的监听器。例如，一个按钮 一个监听器按钮被点击时通知客户。
• 设置可见性：您可以隐藏或显示使用setVisibility（int）。

Note: The Android framework is responsible for measuring, laying out and drawing views. You should not call methods that perform these actions on views yourself unless you are actually implementing aViewGroup.

自定义视图

要实现之定义的View ，你通常要overrides 有些方法 ，这个framework 将要回调所有的views。你不需要覆盖所有这些方法。事实上，你就可以开始只是重写 OnDraw（android.graphics.Canvas） 。

Category	Methods	Description
构造	Constructors	There is a form of the constructor that are called when the view is created from code and a form that is called when the view is inflated from a layout file. The second form should parse and apply any attributes defined in the layout file.
	onFinishInflate()	Called after a view and all of its children has been inflated from XML.
布局t	onMeasure(int, int)	Called to determine the size requirements for this view and all of its children.
	onLayout(boolean, int, int, int, int)	Called when this view should assign a size and position to all of its children.
	onSizeChanged(int, int, int, int)	Called when the size of this view has changed.
画	onDraw(android.graphics.Canvas)	Called when the view should render its content.
事件处理	onKeyDown(int, KeyEvent)	Called when a new hardware key event occurs.
	onKeyUp(int, KeyEvent)	Called when a hardware key up event occurs.
	onTrackballEvent(MotionEvent)	Called when a trackball motion event occurs.
	onTouchEvent(MotionEvent)	Called when a touch screen motion event occurs.
Focus	onFocusChanged(boolean, int, android.graphics.Rect)	Called when the view gains or loses focus.
	onWindowFocusChanged(boolean)	Called when the window containing the view gains or loses focus.
Attaching	onAttachedToWindow()	Called when the view is attached to a window.
	onDetachedFromWindow()	Called when the view is detached from its window.
	onWindowVisibilityChanged(int)	Called when the visibility of the window containing the view has changed.