# ViewGroup

## 属性

ViewGroup继承View后增加的属性不多，但是有几个相关的属性集合和属性需要注意

`ViewGroup`

| 属性                     | 类型                                                            | 说明                  |
| ---------------------- | ------------------------------------------------------------- | ------------------- |
| animateLayoutChanges   | boolean                                                       | 布局发生变化时添加动画效果       |
| clipChildren           | boolean                                                       | 限制子View在其范围内，默认true |
| clipToPadding          | boolean                                                       | 去掉padding的绘制，默认true |
| layoutAnimation        | refrence                                                      | ViewGroup动画效果       |
| animationCache         | boolean                                                       | 子布局也有动画效果           |
| persistentDrawingCache | flag  (none/animation/scrolling/all)                          | 高速缓存的持久性            |
| alwaysDrawnWithCache   | boolean                                                       | 子布局是否应用绘图的高速缓存      |
| addStatesFromChildren  | boolean                                                       | 是否应用子布局的背景          |
| descendantFocusability | enum (beforeDescendants/ afterDescendants/ blocksDescendants) | 子布局焦点获取方式           |
| touchscreenBlocksFocus | boolean                                                       |                     |
| splitMotionEvents      | boolean                                                       | 否传递touch事件到子布局      |
| layoutMode             | enum  (clipBounds/opticalBounds)                              | 边界是否留白              |
| transitionGroup        | boolean                                                       | 过渡整体                |

附：\
<http://blog.163.com/allegro_tyc/blog/static/33743768201371301526104/> <http://blog.csdn.net/jaysong2012/article/details/41047587> <http://www.jcodecraeer.com/a/anzhuokaifa/androidkaifa/2016/0711/4490.html>

`ViewGroup_Layout` 子控件属性，通常使用其扩展ViewGroup\_MarginLayout和其它子类而不直接使用ViewGroup\_Layout

| 属性             | 类型                                                           | 说明    |
| -------------- | ------------------------------------------------------------ | ----- |
| layout\_width  | dimension & enum  (fill\_parent/match\_parent/wrap\_content) | 子控件宽度 |
| layout\_height | dimension & enum                                             | 子控件高度 |

`ViewGroup_MarginLayout` 扩展ViewGroup\_Layout加入margin，需要知道的是这些属性并不是View的属性，虽然我们在布局文件填写参数的时候写在View下面，但是系统读取后，由ViewGroup生成一个`LayoutParams`类赋值给View，具体LayoutParams的类型由ViewGroup确定。

| 属性                   | 类型                                                          | 说明       |
| -------------------- | ----------------------------------------------------------- | -------- |
| layout\_width        | dimension & enum (fill\_parent/match\_parent/wrap\_content) | 子控件宽度    |
| layout\_height       | dimension & enum                                            | 子控件高度    |
| layout\_margin       | dimension                                                   | 与父控件的偏移量 |
| layout\_marginLeft   | dimension                                                   | 具体方向偏移量  |
| layout\_marginTop    | dimension                                                   | 具体方向偏移量  |
| layout\_marginRight  | dimension                                                   | 具体方向偏移量  |
| layout\_marginBottom | dimension                                                   | 具体方向偏移量  |
| layout\_marginStart  | dimension                                                   | 具体方向偏移量  |
| layout\_marginEnd    | dimension                                                   | 具体方向偏移量  |

layout\_gravity(flag) 常见LayoutParams派生类都具有该属性，子控件对齐方式，会和margin冲突； gravity(flag) 常见View和ViewGroup派生类都具有该属性，自身对齐方式； 属性内容是一样的，但记得不是同一个参数作用对象不同，具体意义看名字可以知道不具体说明了

| 属性                 | 说明 |
| ------------------ | -- |
| top                | ～  |
| bottom             |    |
| left               |    |
| right              |    |
| center             |    |
| center\_vertical   |    |
| center\_horizontal |    |
| fill               |    |
| fill\_vertical     |    |
| fill\_horizontal   |    |
| clip\_vertical     |    |
| clip\_horizontal   |    |
| start              |    |
| end                | ～  |


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