自定义View之方法清单

自定义View通常可实现的方法

Creation

• Constructors 构造方法

• onFinishInflate()

  Called after a view and all of its children has been inflated from XML.

  一般用于自定义ViewGroup中，当此ViewGroup及其所有子View从XML中inflate完成后，就会回调此方法。

  另外，重写此方法时，要确保super.onFinishInflate()的执行。

Layout

• onMeasure(int, int)

  Called to determine the size requirements for this view and all of its children.

  用于确定View及其子View的大小区域

  关于测量模式：

  • UNSPECIFIED:父容器没有对当前View有任何限制，当前View可以任意取尺寸

  • EXACTLY:当前的尺寸就是当前View应该取的尺寸

  • AT_MOST:当前尺寸是当前View能取的最大尺寸

    wrap_content -> AT_MOST

    match_parent、固定尺寸 -> EXACTLY

• onLayout(boolean, int, int, int, int)

  Called when this view should assign a size and position to all of its children.

  用于分配子View大小与位置的方法

• onSizeChanged(int, int, int, int)

  Called when the size of this view has changed.

  当View的大小有变化时回调此方法

Drawing

• onDraw(android.graphics.Canvas)

  Called when the view should render its content.

  将View渲染绘制到屏幕上的方法

Event processing

• onKeyDown(int, KeyEvent)

  Called when a new hardware key event occurs.

  物理按键按下的回调

• onKeyUp(int, KeyEvent)

  Called when a hardware key up event occurs.

  物理按键弹起的回调

• onTrackballEvent(MotionEvent)

  Called when a trackball motion event occurs.

  监听轨迹球事件的回调（==现在开发中基本已弃用==，用触摸事件基本可以满足所需功能，轨迹球初始大多用于一些游戏的开发中）

• onTouchEvent(MotionEvent)

  Called when a touch screen motion event occurs.

  触摸屏幕的回调

Focus

• onFocusChanged(boolean, int, android.graphics.Rect)

  Called when the view gains or loses focus.

  View获得或者失去焦点时回调

• onWindowFocusChanged(boolean)

  Called when the window containing the view gains or loses focus.

  包含此View的Window获得or失去焦点时回调此方法

Attaching

• onAttachToWindow()

  Called when the View attached to a window.

  当View被添加到一个Window中时回调此方法

• onDetachedFromWindow()

  Called when the View is dettached from its window

  当View从Window中被移除时回调此方法

• onWindowVisibilityChanged(int)

  Called when the window containing the view has changed

  当此View的Window的可见性发生变化时回调此方法。

关键点

• 自定义View中获取自定义属性是要采用Context中方法，不要采用getResource中的方法，否则自定义属性定义在style中在真机中是无法获取到style中设置的属性。