一 概述
上周一我们发布了[Android 百分比布局库(percent-support-lib) 解析与扩展][1]中对percent-support这个库进行了解析和添加了PercentLinearLayout的支持。
那么为什么本篇博客的存在的意义是什么呢？
首先我们回顾下百分比布局库的用法，提供了PercentRelativeLayout、PercentFrameLayout供大家在编写的时候，对于以下属性：
layout_widthPercent、layout_heightPercent、layout_marginPercent、layout_marginLeftPercent、layout_marginTopPercent、layout_marginRightPercent、layout_marginBottomPercent、layout_marginStartPercent、layout_marginEndPercent。
可以使用百分比进行设置宽、高、边距，的确给我们在适配上提供了极大的便利，但是在使用过程中，觉得存在一些场景无法得到满足。什么场景呢？下面我举几个例子。
当使用图片时，无法设置宽高的比例 比如我们的图片宽高是200*100的，我们在使用过程中我们设置宽高为20%、10%，这样会造成图片的比例失调。为什么呢？因为20%参考的是屏幕的宽度，而10%参考的是屏幕的高度。
很难使用百分比定义一个正方形的控件 比如，我现在界面的右下角有一个
FloatingActionButton，我希望其宽度和高度都为屏幕宽度的10%，很难做到。一个控件的margin四个方向值一致 有些时候，我设置margin，我希望四边的边距一致的，但是如果目前设置5%，会造成，上下为高度的5%，左右边距为宽度的5%。
综合上述这些问题，可以发现目前的percent-support-lib并不能完全满足我们的需求，所以我们考虑对其进行扩展。说白了，我们就希望在布局的时候可以自己设定参考看度还是高度，比如上述2，我们对于宽高可以写成10%w，10%w。也就是在不改变原库的用法的前提下，添加一些额外的支持。
二 扩展的功能
目前我初步对该库进行了改写，github地址：[android-percent-support-extend][2]，对于官方库，做了如下的改变：
不改变原有库的用法
添加了
PercentLinearLayout支持百分比指定特定的参考值，比如宽度或者高度。 例如：
app:layout_heightPercent="50%w",app:layout_marginPercent="15%w",app:layout_marginBottomPercent="20%h".- 支持通过app:layout_textSizePercent设置textView的textSize
- 对于外层套ScrollView的问题，目前可以在
PercentLinearLayout的外层使用ScrollView，不过对于宽度的百分比参考的就是android.R.id.content的高度(因为，无法参考父控件的高度，父控件的高度理论上依赖于子View高度，且模式为UNSPECIFIED)。
对于如何导入，也是相当的简单，android studio的用户，直接： ```
dependencies { //... compile 'com.zhy:percent-support-extends:1.0.1' }
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不需要导入官方的percent-support-lib了。
对于的三个类分别为：
```
`com.zhy.android.percent.support.PercentLinearLayout
com.zhy.android.percent.support.PercentRelativeLayout
com.zhy.android.percent.support.PercentFrameLayout`
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对于eclipse的用户：github上自行下载源码，就几个类和一个attrs.xml，也可以在[bintray.com/percent-support-extends][3] 下载相关文件。
下面看几个具体的示例。
* * *
### <a name="t2"></a>三 具体的示例 {#三-具体的示例}
#### <a name="t3"></a>Demo 1 {#demo-1}
xml:
```
`<span class=“hljs-pi”><?xml version=“1.0” encoding=“utf-8”?></span>
<span class=“hljs-tag”><<span class=“hljs-title”>com.zhy.android.percent.support.PercentFrameLayout </span> <span class=“hljs-attribute”>xmlns:android</span>=<span class=“hljs-value”>“http://schemas.android.com/apk/res/android"</span> <span class=“hljs-attribute”>xmlns:app</span>=<span class=“hljs-value”>“http://schemas.android.com/apk/res-auto"</span> <span class=“hljs-attribute”>android:layout_width</span>=<span class=“hljs-value”>“match_parent”</span> <span class=“hljs-attribute”>android:layout_height</span>=<span class=“hljs-value”>“match_parent”</span> <span class=“hljs-attribute”>android:orientation</span>=<span class=“hljs-value”>“vertical”</span>></span>
<span class="hljs-tag"><<span class="hljs-title">com.zhy.android.percent.support.PercentFrameLayout
</span> <span class=“hljs-attribute”>android:layout_width</span>=<span class=“hljs-value”>“0dp”</span> <span class=“hljs-attribute”>android:layout_height</span>=<span class=“hljs-value”>“0dp”</span> <span class=“hljs-attribute”>android:layout_gravity</span>=<span class=“hljs-value”>“center”</span> <span class=“hljs-attribute”>android:background</span>=<span class=“hljs-value”>"#ff44aacc”</span> <span class=“hljs-attribute”>app:layout_heightPercent</span>=<span class=“hljs-value”>“50%w”</span> <span class=“hljs-attribute”>app:layout_widthPercent</span>=<span class=“hljs-value”>“50%w”</span>></span>
<span class="hljs-tag"><<span class="hljs-title">com.zhy.android.percent.support.PercentFrameLayout
</span> <span class=“hljs-attribute”>android:layout_width</span>=<span class=“hljs-value”>“0dp”</span> <span class=“hljs-attribute”>android:layout_height</span>=<span class=“hljs-value”>“0dp”</span> <span class=“hljs-attribute”>android:layout_gravity</span>=<span class=“hljs-value”>“center”</span> <span class=“hljs-attribute”>android:background</span>=<span class=“hljs-value”>"#ffcc5ec7”</span> <span class=“hljs-attribute”>app:layout_heightPercent</span>=<span class=“hljs-value”>“50%w”</span> <span class=“hljs-attribute”>app:layout_widthPercent</span>=<span class=“hljs-value”>“50%w”</span>></span>
<span class="hljs-tag"><<span class="hljs-title">TextView
</span> <span class=“hljs-attribute”>android:layout_width</span>=<span class=“hljs-value”>“match_parent”</span> <span class=“hljs-attribute”>android:layout_height</span>=<span class=“hljs-value”>“match_parent”</span> <span class=“hljs-attribute”>android:layout_gravity</span>=<span class=“hljs-value”>“center”</span> <span class=“hljs-attribute”>android:background</span>=<span class=“hljs-value”>"#ff7ecc16"</span> <span class=“hljs-attribute”>android:gravity</span>=<span class=“hljs-value”>“center”</span> <span class=“hljs-attribute”>android:text</span>=<span class=“hljs-value”>“margin 15% of w”</span> <span class=“hljs-attribute”>app:layout_marginPercent</span>=<span class=“hljs-value”>“15%w”</span> /></span>
<span class="hljs-tag"></<span class="hljs-title">com.zhy.android.percent.support.PercentFrameLayout</span>></span>
<span class="hljs-tag"></<span class="hljs-title">com.zhy.android.percent.support.PercentFrameLayout</span>></span>
<span class="hljs-tag"><<span class="hljs-title">TextView</span> <span class="hljs-attribute">android:layout_width</span>=<span class="hljs-value">"0dp"</span>
<span class="hljs-attribute">android:layout_height</span>=<span class="hljs-value">"0dp"</span>
<span class="hljs-attribute">android:layout_gravity</span>=<span class="hljs-value">"bottom|right"</span>
<span class="hljs-attribute">android:background</span>=<span class="hljs-value">"#44ff0000"</span>
<span class="hljs-attribute">android:gravity</span>=<span class="hljs-value">"center"</span>
<span class="hljs-attribute">android:text</span>=<span class="hljs-value">"15%w,15%w"</span>
<span class="hljs-attribute">app:layout_heightPercent</span>=<span class="hljs-value">"15%w"</span>
<span class="hljs-attribute">app:layout_marginPercent</span>=<span class="hljs-value">"5%w"</span>
<span class="hljs-attribute">app:layout_widthPercent</span>=<span class="hljs-value">"15%w"</span>/></span>
<span class=“hljs-tag”></<span class=“hljs-title”>com.zhy.android.percent.support.PercentFrameLayout</span>></span> `
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#### <a name="t4"></a>Demo 2 {#demo-2}
xml:
```
`<span class="hljs-pi"><?xml version="1.0" encoding="utf-8"?></span>
<span class="hljs-tag"><<span class="hljs-title">com.zhy.android.percent.support.PercentRelativeLayout
</span> <span class="hljs-attribute">xmlns:android</span>=<span class="hljs-value">"http://schemas.android.com/apk/res/android"</span>
<span class="hljs-attribute">xmlns:app</span>=<span class="hljs-value">"http://schemas.android.com/apk/res-auto"</span>
<span class="hljs-attribute">android:layout_width</span>=<span class="hljs-value">"match_parent"</span>
<span class="hljs-attribute">android:layout_height</span>=<span class="hljs-value">"match_parent"</span>
<span class="hljs-attribute">android:clickable</span>=<span class="hljs-value">"true"</span>></span>
<span class="hljs-tag"><<span class="hljs-title">TextView
</span> <span class="hljs-attribute">android:id</span>=<span class="hljs-value">"@+id/row_one_item_one"</span>
<span class="hljs-attribute">android:layout_width</span>=<span class="hljs-value">"0dp"</span>
<span class="hljs-attribute">android:layout_height</span>=<span class="hljs-value">"0dp"</span>
<span class="hljs-attribute">android:layout_alignParentTop</span>=<span class="hljs-value">"true"</span>
<span class="hljs-attribute">android:background</span>=<span class="hljs-value">"#7700ff00"</span>
<span class="hljs-attribute">android:text</span>=<span class="hljs-value">"w:70%,h:20%"</span>
<span class="hljs-attribute">android:gravity</span>=<span class="hljs-value">"center"</span>
<span class="hljs-attribute">app:layout_heightPercent</span>=<span class="hljs-value">"20%"</span>
<span class="hljs-attribute">app:layout_widthPercent</span>=<span class="hljs-value">"70%"</span>/></span>
<span class="hljs-tag"><<span class="hljs-title">TextView
</span> <span class="hljs-attribute">android:id</span>=<span class="hljs-value">"@+id/row_one_item_two"</span>
<span class="hljs-attribute">android:layout_width</span>=<span class="hljs-value">"0dp"</span>
<span class="hljs-attribute">android:layout_height</span>=<span class="hljs-value">"0dp"</span>
<span class="hljs-attribute">android:layout_toRightOf</span>=<span class="hljs-value">"@+id/row_one_item_one"</span>
<span class="hljs-attribute">android:background</span>=<span class="hljs-value">"#396190"</span>
<span class="hljs-attribute">android:text</span>=<span class="hljs-value">"w:30%,h:20%"</span>
<span class="hljs-attribute">app:layout_heightPercent</span>=<span class="hljs-value">"20%"</span>
<span class="hljs-attribute">android:gravity</span>=<span class="hljs-value">"center"</span>
<span class="hljs-attribute">app:layout_widthPercent</span>=<span class="hljs-value">"30%"</span>/></span>
<span class="hljs-tag"><<span class="hljs-title">ImageView
</span> <span class="hljs-attribute">android:id</span>=<span class="hljs-value">"@+id/row_two_item_one"</span>
<span class="hljs-attribute">android:layout_width</span>=<span class="hljs-value">"match_parent"</span>
<span class="hljs-attribute">android:layout_height</span>=<span class="hljs-value">"0dp"</span>
<span class="hljs-attribute">android:src</span>=<span class="hljs-value">"@drawable/tangyan"</span>
<span class="hljs-attribute">android:scaleType</span>=<span class="hljs-value">"centerCrop"</span>
<span class="hljs-attribute">android:layout_below</span>=<span class="hljs-value">"@+id/row_one_item_one"</span>
<span class="hljs-attribute">android:background</span>=<span class="hljs-value">"#d89695"</span>
<span class="hljs-attribute">app:layout_heightPercent</span>=<span class="hljs-value">"70%"</span>/></span>
<span class="hljs-tag"><<span class="hljs-title">TextView
</span> <span class="hljs-attribute">android:layout_width</span>=<span class="hljs-value">"0dp"</span>
<span class="hljs-attribute">android:layout_height</span>=<span class="hljs-value">"0dp"</span>
<span class="hljs-attribute">android:layout_below</span>=<span class="hljs-value">"@id/row_two_item_one"</span>
<span class="hljs-attribute">android:background</span>=<span class="hljs-value">"#770000ff"</span>
<span class="hljs-attribute">android:gravity</span>=<span class="hljs-value">"center"</span>
<span class="hljs-attribute">android:text</span>=<span class="hljs-value">"width:100%,height:10%"</span>
<span class="hljs-attribute">app:layout_heightPercent</span>=<span class="hljs-value">"10%"</span>
<span class="hljs-attribute">app:layout_widthPercent</span>=<span class="hljs-value">"100%"</span>/></span>
<span class="hljs-tag"></<span class="hljs-title">com.zhy.android.percent.support.PercentRelativeLayout</span>></span>
`
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ok，例子都比较简单，主要就一个布局文件，可以看出上述我们可以给宽度、高度，边距等指定参考值为宽度或者高度。这样的话，在保证图片宽、高比例、控件设置为正方形等需求就没问题了。
* * *
接下来还有个例子，功能主要是设置TextView对于textSize的百分比设置；以及对于ScrollView的支持。当然了，对于ScrollView的支持，这个理论上是不支持的，因为大家都清楚，如果`PercentLinearLayout`在ScrollView中，那么高度的模式肯定是`UNSPECIFIED`，那么理论上来说高度是无限制的，也就是依赖于子View的高度，而百分比布局的高度是依赖于父View的高度的，所有是互斥的。而我们支持是：考虑到编写代码的时候，大多参考的是屏幕高度（android.R.id.content）的高度，所以如果在ScrollView中，编写10%h，这个百分比是依赖于屏幕高度的（不包括ActionBar的高度）。
#### <a name="t5"></a>Demo 3 {#demo-3}
xml:
```
`<span class=“hljs-pi”><?xml version=“1.0” encoding=“utf-8”?></span>
<span class=“hljs-tag”><<span class=“hljs-title”>ScrollView </span> <span class=“hljs-attribute”>xmlns:android</span>=<span class=“hljs-value”>“http://schemas.android.com/apk/res/android"</span> <span class=“hljs-attribute”>xmlns:app</span>=<span class=“hljs-value”>“http://schemas.android.com/apk/res-auto"</span> <span class=“hljs-attribute”>android:layout_width</span>=<span class=“hljs-value”>“match_parent”</span> <span class=“hljs-attribute”>android:layout_height</span>=<span class=“hljs-value”>“match_parent”</span>></span> <span class=“hljs-tag”><<span class=“hljs-title”>com.zhy.android.percent.support.PercentLinearLayout </span> <span class=“hljs-attribute”>xmlns:android</span>=<span class=“hljs-value”>“http://schemas.android.com/apk/res/android"</span> <span class=“hljs-attribute”>xmlns:app</span>=<span class=“hljs-value”>“http://schemas.android.com/apk/res-auto"</span> <span class=“hljs-attribute”>android:layout_width</span>=<span class=“hljs-value”>“match_parent”</span> <span class=“hljs-attribute”>android:layout_height</span>=<span class=“hljs-value”>“wrap_content”</span> <span class=“hljs-attribute”>android:orientation</span>=<span class=“hljs-value”>“vertical”</span>></span>
<span class="hljs-tag"><<span class="hljs-title">TextView
</span> <span class=“hljs-attribute”>android:layout_width</span>=<span class=“hljs-value”>“0dp”</span> <span class=“hljs-attribute”>android:layout_height</span>=<span class=“hljs-value”>“0dp”</span> <span class=“hljs-attribute”>android:background</span>=<span class=“hljs-value”>"#ff44aacc”</span> <span class=“hljs-attribute”>android:gravity</span>=<span class=“hljs-value”>“center”</span> <span class=“hljs-attribute”>android:text</span>=<span class=“hljs-value”>“width:60%,height:5%,ts:3%"</span> <span class=“hljs-attribute”>android:textColor</span>=<span class=“hljs-value”>"#ffffff”</span> <span class=“hljs-attribute”>app:layout_heightPercent</span>=<span class=“hljs-value”>“5%"</span> <span class=“hljs-attribute”>app:layout_marginBottomPercent</span>=<span class=“hljs-value”>“5%"</span> <span class=“hljs-attribute”>app:layout_textSizePercent</span>=<span class=“hljs-value”>“3%"</span> <span class=“hljs-attribute”>app:layout_widthPercent</span>=<span class=“hljs-value”>“60%"</span>/></span>
<span class="hljs-tag"><<span class="hljs-title">TextView
</span> <span class=“hljs-attribute”>android:layout_width</span>=<span class=“hljs-value”>“0dp”</span> <span class=“hljs-attribute”>android:layout_height</span>=<span class=“hljs-value”>“0dp”</span> <span class=“hljs-attribute”>android:background</span>=<span class=“hljs-value”>"#ff4400cc”</span> <span class=“hljs-attribute”>android:gravity</span>=<span class=“hljs-value”>“center”</span> <span class=“hljs-attribute”>android:text</span>=<span class=“hljs-value”>“width:70%,height:10%"</span> <span class=“hljs-attribute”>android:textColor</span>=<span class=“hljs-value”>"#ffffff”</span> <span class=“hljs-attribute”>app:layout_heightPercent</span>=<span class=“hljs-value”>“10%"</span> <span class=“hljs-attribute”>app:layout_marginBottomPercent</span>=<span class=“hljs-value”>“5%"</span> <span class=“hljs-attribute”>app:layout_widthPercent</span>=<span class=“hljs-value”>“70%"</span>/></span> <span class=“hljs-tag”><<span class=“hljs-title”>TextView </span> <span class=“hljs-attribute”>android:layout_width</span>=<span class=“hljs-value”>“0dp”</span> <span class=“hljs-attribute”>android:layout_height</span>=<span class=“hljs-value”>“0dp”</span> <span class=“hljs-attribute”>android:background</span>=<span class=“hljs-value”>"#ff44aacc”</span> <span class=“hljs-attribute”>android:gravity</span>=<span class=“hljs-value”>“center”</span> <span class=“hljs-attribute”>android:text</span>=<span class=“hljs-value”>“w:80%,h:15%,textSize:5%"</span> <span class=“hljs-attribute”>android:textColor</span>=<span class=“hljs-value”>"#ffffff”</span> <span class=“hljs-attribute”>app:layout_heightPercent</span>=<span class=“hljs-value”>“15%"</span> <span class=“hljs-attribute”>app:layout_marginBottomPercent</span>=<span class=“hljs-value”>“5%"</span> <span class=“hljs-attribute”>app:layout_textSizePercent</span>=<span class=“hljs-value”>“5%"</span> <span class=“hljs-attribute”>app:layout_widthPercent</span>=<span class=“hljs-value”>“80%"</span>/></span> <span class=“hljs-tag”><<span class=“hljs-title”>TextView </span> <span class=“hljs-attribute”>android:layout_width</span>=<span class=“hljs-value”>“0dp”</span> <span class=“hljs-attribute”>android:layout_height</span>=<span class=“hljs-value”>“0dp”</span> <span class=“hljs-attribute”>android:background</span>=<span class=“hljs-value”>"#ff4400cc”</span> <span class=“hljs-attribute”>android:gravity</span>=<span class=“hljs-value”>“center”</span> <span class=“hljs-attribute”>android:text</span>=<span class=“hljs-value”>“width:90%,height:5%"</span> <span class=“hljs-attribute”>android:textColor</span>=<span class=“hljs-value”>"#ffffff”</span> <span class=“hljs-attribute”>app:layout_heightPercent</span>=<span class=“hljs-value”>“20%"</span> <span class=“hljs-attribute”>app:layout_marginBottomPercent</span>=<span class=“hljs-value”>“5%"</span> <span class=“hljs-attribute”>app:layout_widthPercent</span>=<span class=“hljs-value”>“90%"</span>/></span>
<span class="hljs-tag"><<span class="hljs-title">TextView
</span> <span class=“hljs-attribute”>android:layout_width</span>=<span class=“hljs-value”>“match_parent”</span> <span class=“hljs-attribute”>android:layout_height</span>=<span class=“hljs-value”>“0dp”</span> <span class=“hljs-attribute”>android:background</span>=<span class=“hljs-value”>"#ff44aacc”</span> <span class=“hljs-attribute”>android:gravity</span>=<span class=“hljs-value”>“center”</span> <span class=“hljs-attribute”>android:text</span>=<span class=“hljs-value”>“width:100%,height:25%"</span> <span class=“hljs-attribute”>android:textColor</span>=<span class=“hljs-value”>"#ffffff”</span> <span class=“hljs-attribute”>app:layout_heightPercent</span>=<span class=“hljs-value”>“25%"</span> <span class=“hljs-attribute”>app:layout_marginBottomPercent</span>=<span class=“hljs-value”>“5%"</span> /></span>
<span class="hljs-tag"><<span class="hljs-title">TextView
</span> <span class=“hljs-attribute”>android:layout_width</span>=<span class=“hljs-value”>“match_parent”</span> <span class=“hljs-attribute”>android:layout_height</span>=<span class=“hljs-value”>“0dp”</span> <span class=“hljs-attribute”>android:background</span>=<span class=“hljs-value”>"#ff44aacc”</span> <span class=“hljs-attribute”>android:gravity</span>=<span class=“hljs-value”>“center”</span> <span class=“hljs-attribute”>android:text</span>=<span class=“hljs-value”>“width:100%,height:30%"</span> <span class=“hljs-attribute”>android:textColor</span>=<span class=“hljs-value”>"#ffffff”</span> <span class=“hljs-attribute”>app:layout_heightPercent</span>=<span class=“hljs-value”>“30%"</span> <span class=“hljs-attribute”>app:layout_marginBottomPercent</span>=<span class=“hljs-value”>“5%"</span> /></span>
<span class="hljs-tag"></<span class="hljs-title">com.zhy.android.percent.support.PercentLinearLayout</span>></span>
<span class=“hljs-tag”></<span class=“hljs-title”>ScrollView</span>></span>
`
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上面的第三个TextView的字体设置的就是5%（默认参考容器高度）。整个PercentLinearLayout在ScrollView中。ok~ 姑且这样，由于源码比较简单，大家可以根据自己的实际需求去修改，前提尽可能不要改变原有的功能。
* * *
### <a name="t6"></a>四 扩展的相关源码 {#四-扩展的相关源码}
#### <a name="t7"></a>(一) 关于attrs.xml {#一-关于attrsxml}
原库中所有的属性的format为fraction，但是由于我期望的写法有10%w，10%h，10%，没有找到合适的format，就直接定义为string了~string我可以自己去解析~
```
`<span class="hljs-pi"><?xml version="1.0" encoding="utf-8"?></span>
<span class="hljs-tag"><<span class="hljs-title">resources</span>></span>
<span class="hljs-tag"><<span class="hljs-title">declare-styleable</span> <span class="hljs-attribute">name</span>=<span class="hljs-value">"PercentLayout_Layout"</span>></span>
<span class="hljs-tag"><<span class="hljs-title">attr</span> <span class="hljs-attribute">name</span>=<span class="hljs-value">"layout_widthPercent"</span> <span class="hljs-attribute">format</span>=<span class="hljs-value">"string"</span>/></span>
<span class="hljs-tag"><<span class="hljs-title">attr</span> <span class="hljs-attribute">name</span>=<span class="hljs-value">"layout_heightPercent"</span> <span class="hljs-attribute">format</span>=<span class="hljs-value">"string"</span>/></span>
<span class="hljs-tag"><<span class="hljs-title">attr</span> <span class="hljs-attribute">name</span>=<span class="hljs-value">"layout_marginPercent"</span> <span class="hljs-attribute">format</span>=<span class="hljs-value">"string"</span>/></span>
<span class="hljs-tag"><<span class="hljs-title">attr</span> <span class="hljs-attribute">name</span>=<span class="hljs-value">"layout_marginLeftPercent"</span> <span class="hljs-attribute">format</span>=<span class="hljs-value">"string"</span>/></span>
<span class="hljs-tag"><<span class="hljs-title">attr</span> <span class="hljs-attribute">name</span>=<span class="hljs-value">"layout_marginTopPercent"</span> <span class="hljs-attribute">format</span>=<span class="hljs-value">"string"</span>/></span>
<span class="hljs-tag"><<span class="hljs-title">attr</span> <span class="hljs-attribute">name</span>=<span class="hljs-value">"layout_marginRightPercent"</span> <span class="hljs-attribute">format</span>=<span class="hljs-value">"string"</span>/></span>
<span class="hljs-tag"><<span class="hljs-title">attr</span> <span class="hljs-attribute">name</span>=<span class="hljs-value">"layout_marginBottomPercent"</span> <span class="hljs-attribute">format</span>=<span class="hljs-value">"string"</span>/></span>
<span class="hljs-tag"><<span class="hljs-title">attr</span> <span class="hljs-attribute">name</span>=<span class="hljs-value">"layout_marginStartPercent"</span> <span class="hljs-attribute">format</span>=<span class="hljs-value">"string"</span>/></span>
<span class="hljs-tag"><<span class="hljs-title">attr</span> <span class="hljs-attribute">name</span>=<span class="hljs-value">"layout_marginEndPercent"</span> <span class="hljs-attribute">format</span>=<span class="hljs-value">"string"</span>/></span>
<span class="hljs-tag"><<span class="hljs-title">attr</span> <span class="hljs-attribute">name</span>=<span class="hljs-value">"layout_textSizePercent"</span> <span class="hljs-attribute">format</span>=<span class="hljs-value">"string"</span>/></span>
<span class="hljs-tag"></<span class="hljs-title">declare-styleable</span>></span>
<span class="hljs-tag"></<span class="hljs-title">resources</span>></span>
`
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#### <a name="t8"></a>（二） 获取自定义属性的值及使用 {#二-获取自定义属性的值及使用}
如果看了上篇博文的话，应该清楚，对于自定义属性的值是在`PercentLayoutHelper.getPercentLayoutInfo(c, attrs)`中获取的。
简单看下修改后的代码：
```
` <span class=“hljs-keyword”>public</span> <span class=“hljs-keyword”>static</span> PercentLayoutInfo <span class=“hljs-title”>getPercentLayoutInfo</span>(Context context, AttributeSet attrs) { PercentLayoutInfo info = <span class=“hljs-keyword”>null</span>; TypedArray array = context.obtainStyledAttributes(attrs, R.styleable.PercentLayout_Layout);
String sizeStr = array.getString(R.styleable.PercentLayout_Layout_layout_widthPercent);
PercentLayoutInfo.PercentVal percentVal = getPercentVal(sizeStr, <span class="hljs-keyword">true</span>);
<span class="hljs-keyword">if</span> (percentVal != <span class="hljs-keyword">null</span>)
{
<span class="hljs-keyword">if</span> (Log.isLoggable(TAG, Log.VERBOSE))
{
Log.v(TAG, <span class="hljs-string">"percent width: "</span> + percentVal.percent);
}
info = info != <span class="hljs-keyword">null</span> ? info : <span class="hljs-keyword">new</span> PercentLayoutInfo();
info.widthPercent = percentVal;
}
<span class="hljs-comment">//省略了获取其他的类似属性</span>
array.recycle();
<span class="hljs-keyword">return</span> info;
}
<span class="hljs-keyword">private</span> <span class="hljs-keyword">static</span> <span class="hljs-keyword">final</span> String REGEX_PERCENT = <span class="hljs-string">"^(([0-9]+)([.]([0-9]+))?|([.]([0-9]+))?)%([wh]?)$"</span>;
<span class="hljs-javadoc">/**
* widthStr to PercentVal
* <br/>
* eg: 35%w => new PercentVal(35, true)
*
*<span class="hljs-javadoctag"> @param</span> percentStr
*<span class="hljs-javadoctag"> @param</span> isOnWidth
*<span class="hljs-javadoctag"> @return</span>
*/</span>
<span class="hljs-keyword">private</span> <span class="hljs-keyword">static</span> PercentLayoutInfo.PercentVal <span class="hljs-title">getPercentVal</span>(String percentStr, <span class="hljs-keyword">boolean</span> isOnWidth)
{
<span class="hljs-comment">//valid param</span>
<span class="hljs-keyword">if</span> (percentStr == <span class="hljs-keyword">null</span>)
{
<span class="hljs-keyword">return</span> <span class="hljs-keyword">null</span>;
}
Pattern p = Pattern.compile(REGEX_PERCENT);
Matcher matcher = p.matcher(percentStr);
<span class="hljs-keyword">if</span> (!matcher.matches())
{
<span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> RuntimeException(<span class="hljs-string">"the value of layout_xxxPercent invalid! ==>"</span> + percentStr);
}
<span class="hljs-keyword">int</span> len = percentStr.length();
<span class="hljs-comment">//extract the float value</span>
String floatVal = matcher.group(<span class="hljs-number">1</span>);
String lastAlpha = percentStr.substring(len - <span class="hljs-number">1</span>);
<span class="hljs-keyword">float</span> percent = Float.parseFloat(floatVal) / <span class="hljs-number">100</span>f;
<span class="hljs-keyword">boolean</span> isBasedWidth = (isOnWidth && !lastAlpha.equals(<span class="hljs-string">"h"</span>)) || lastAlpha.equals(<span class="hljs-string">"w"</span>);
<span class="hljs-keyword">return</span> <span class="hljs-keyword">new</span> PercentLayoutInfo.PercentVal(percent, isBasedWidth);
}
`
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首先我们获取自定义属性的填写的值，通过getPercentVal方法，在该方法内部通过正则校验其合法性，如果合法，则将其拆解封装成PercentVal对象，该对象中记录百分比值，已经知否参考宽度的布尔值（如果参考宽度则为true，否则为false）。对于没有后缀w|h的，和原库的解析方式相同。
PercentVal对象如下:
```
`public static class PercentVal
{
public float percent = -1;
public boolean isBaseWidth;
public PercentVal(float percent, boolean isBaseWidth)
{
this.percent = percent;
this.isBaseWidth = isBaseWidth;
}
} `
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对于定义的自定义属性获取完成之后，剩下的无非是测量时候对于原本的LayoutParams中的宽度和高度的赋值做简单的修改。参考上一篇的源码，我们直接看 `PercentLayoutInfo.fillLayoutParams(params, widthHint, heightHint);`方法：
```
` <span class=“hljs-keyword”>public</span> <span class=“hljs-keyword”>void</span> <span class=“hljs-title”>fillLayoutParams</span>(ViewGroup.LayoutParams params, <span class=“hljs-keyword”>int</span> widthHint, <span class=“hljs-keyword”>int</span> heightHint) { <span class=“hljs-comment”>// Preserve the original layout params, so we can restore them after the measure step.</span> mPreservedParams.width = params.width; mPreservedParams.height = params.height; <span class=“hljs-comment”>/* if (widthPercent >= 0) { params.width = (int) (widthHint * widthPercent); } if (heightPercent >= 0) { params.height = (int) (heightHint * heightPercent); }*/</span> <span class=“hljs-keyword”>if</span> (widthPercent != <span class=“hljs-keyword”>null</span>) { <span class=“hljs-keyword”>int</span> base = widthPercent.isBaseWidth ? widthHint : heightHint; params.width = (<span class=“hljs-keyword”>int</span>) (base * widthPercent.percent); } <span class=“hljs-keyword”>if</span> (heightPercent != <span class=“hljs-keyword”>null</span>) { <span class=“hljs-keyword”>int</span> base = heightPercent.isBaseWidth ? widthHint : heightHint; params.height = (<span class=“hljs-keyword”>int</span>) (base * heightPercent.percent); }
<span class="hljs-keyword">if</span> (Log.isLoggable(TAG, Log.DEBUG))
{
Log.d(TAG, <span class="hljs-string">"after fillLayoutParams: ("</span> + params.width + <span class="hljs-string">", "</span> + params.height + <span class="hljs-string">")"</span>);
}
}
`
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原本的源码比较简单，只需要将widthHint/heightHint乘以百分比即可（见上代码注释），而我们修改的也比较容易，首先判断参考宽度还是高度，然后乘以百分比（根据我们的对象PercentVal的属性）。
ok，大概的源码修改就是上述的内容，有兴趣的可以直接查看源码。
当然了，上述库中肯定还存在或多或少的问题，大家可以fork完善下，或者直接留言提意见都可以。
* * *
github地址：[android-percent-support-extend][2] ，用法参考上文，或者README。欢迎star and fork 。
~~have a nice day ~~
ok~
[1]: http://blog.csdn.net/lmj623565791/article/details/46695347
[2]: https://github.com/hongyangAndroid/android-percent-support-extend
[3]: https://bintray.com/hongyangandroid/maven/android-screen-support-ext/view#files
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