Android 百分比布局库(percent-support-lib) 解析与扩展


androidsupportpercent

目录(?)[+]

一概述二使用

一PercentFrameLayout二 PercentRelativeLayout
三源码分析

一percent相关属性的获取二 onMeasue中重新计算child的尺寸
三实现PercentLinearlayout

一PercentLinearLayout二测试布局
三效果图

转载请标明出处：
http://blog.csdn.net/lmj623565791/article/details/46695347；
本文出自:【张鸿洋的博客】

一、概述

周末游戏打得过猛，于是周天熬夜码代码，周一早上浑浑噩噩的发现android-percent-support-lib-sample这个项目，Google终于开始支持百分比的方式布局了，瞬间脉动回来，啊咧咧。对于这种历史性的时刻，不出篇博客难以表达我内心的激动。

还记得不久前，发了篇博客：Android 屏幕适配方案，这篇博客以Web页面设计引出一种适配方案，最终的目的就是可以通过百分比控制控件的大小。当然了，存在一些问题，比如：

对于没有考虑到屏幕尺寸，可能会出现意外的情况；apk的大小会增加；

当然了android-percent-support这个库，基本可以解决上述问题，是不是有点小激动，稍等，我们先描述下这个support-lib。

这个库提供了：

两种布局供大家使用：
PercentRelativeLayout、PercentFrameLayout，通过名字就可以看出，这是继承自FrameLayout和RelativeLayout两个容器类；

支持的属性有：

layout_widthPercent、layout_heightPercent、
layout_marginPercent、layout_marginLeftPercent、
layout_marginTopPercent、layout_marginRightPercent、
layout_marginBottomPercent、layout_marginStartPercent、layout_marginEndPercent。

可以看到支持宽高，以及margin。

也就是说，大家只要在开发过程中使用PercentRelativeLayout、PercentFrameLayout替换FrameLayout、RelativeLayout即可。

是不是很简单，不过貌似没有LinearLayout，有人会说LinearLayout有weight属性呀。但是，weight属性只能支持一个方向呀~~哈，没事，刚好给我们一个机会去自定义一个PercentLinearLayout。

好了，本文分为3个部分：

PercentRelativeLayout、PercentFrameLayout的使用对上述控件源码分析自定义PercentLinearLayout

二、使用

关于使用，其实及其简单，并且github上也有例子，android-percent-support-lib-sample。我们就简单过一下：

首先记得在build.gradle添加：

<code class="language-xml hljs  has-numbering"> compile 'com.android.support:percent:22.2.0'</code><ul class="pre-numbering" style="display: block;"><li>1</li></ul>

（一）PercentFrameLayout

<code class="language-xml hljs  has-numbering"><span class="hljs-pi"><?xml version="1.0" encoding="utf-8"?></span>
<span class="hljs-tag"><<span class="hljs-title">android.support.percent.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>

    <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">"left|top"</span>
        <span class="hljs-attribute">android:background</span>=<span class="hljs-value">"#44ff0000"</span>
        <span class="hljs-attribute">android:text</span>=<span class="hljs-value">"width:30%,height: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">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">"right|top"</span>
        <span class="hljs-attribute">android:gravity</span>=<span class="hljs-value">"center"</span>
        <span class="hljs-attribute">android:background</span>=<span class="hljs-value">"#4400ff00"</span>
        <span class="hljs-attribute">android:text</span>=<span class="hljs-value">"width:70%,height:20%"</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: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"</span>
        <span class="hljs-attribute">android:background</span>=<span class="hljs-value">"#770000ff"</span>
        <span class="hljs-attribute">android:text</span>=<span class="hljs-value">"width:100%,height:10%"</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">"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">android.support.percent.PercentFrameLayout</span>></span>
</code><ul class="pre-numbering" style="display: block;"><li>1</li><li>2</li><li>3</li><li>4</li><li>5</li><li>6</li><li>7</li><li>8</li><li>9</li><li>10</li><li>11</li><li>12</li><li>13</li><li>14</li><li>15</li><li>16</li><li>17</li><li>18</li><li>19</li><li>20</li><li>21</li><li>22</li><li>23</li><li>24</li><li>25</li><li>26</li><li>27</li><li>28</li><li>29</li><li>30</li><li>31</li><li>32</li><li>33</li><li>34</li><li>35</li><li>36</li><li>37</li><li>38</li><li>39</li><li>40</li><li>41</li></ul>

3个TextView，很简单，直接看效果图：

(二) PercentRelativeLayout

<code class="language-xml hljs  has-numbering"><span class="hljs-pi"><?xml version="1.0" encoding="utf-8"?></span>
<span class="hljs-tag"><<span class="hljs-title">android.support.percent.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">android.support.percent.PercentRelativeLayout</span>></span>

</code><ul class="pre-numbering" style="display: block;"><li>1</li><li>2</li><li>3</li><li>4</li><li>5</li><li>6</li><li>7</li><li>8</li><li>9</li><li>10</li><li>11</li><li>12</li><li>13</li><li>14</li><li>15</li><li>16</li><li>17</li><li>18</li><li>19</li><li>20</li><li>21</li><li>22</li><li>23</li><li>24</li><li>25</li><li>26</li><li>27</li><li>28</li><li>29</li><li>30</li><li>31</li><li>32</li><li>33</li><li>34</li><li>35</li><li>36</li><li>37</li><li>38</li><li>39</li><li>40</li><li>41</li><li>42</li><li>43</li><li>44</li><li>45</li><li>46</li><li>47</li><li>48</li><li>49</li><li>50</li><li>51</li><li>52</li><li>53</li><li>54</li><li>55</li></ul>

ok，依然是直接看效果图:

使用没什么好说的，就是直观的看一下。

三、源码分析

其实细想一下，Google只是对我们原本熟悉的RelativeLayout和FrameLayout进行的功能的扩展，使其支持了percent相关的属性。

那么，我们考虑下，如果是我们添加这种扩展，我们会怎么做：

通过LayoutParams获取child设置的percent相关属性的值onMeasure的时候，将child的width,height的值，通过获取的自定义属性的值进行计算（eg:容器的宽 * fraction ），计算后传入给child.measure(w,h);

ok，有了上面的猜想，我们直接看PercentFrameLayout的源码。

<code class="language-java hljs  has-numbering"><span class="hljs-keyword">public</span> <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">PercentFrameLayout</span> <span class="hljs-keyword">extends</span> <span class="hljs-title">FrameLayout</span> {</span>
    <span class="hljs-keyword">private</span> <span class="hljs-keyword">final</span> PercentLayoutHelper mHelper = <span class="hljs-keyword">new</span> PercentLayoutHelper(<span class="hljs-keyword">this</span>);

    <span class="hljs-comment">//省略了，两个构造方法</span>

    <span class="hljs-keyword">public</span> <span class="hljs-title">PercentFrameLayout</span>(Context context, AttributeSet attrs) {
        <span class="hljs-keyword">super</span>(context, attrs);
    }

    <span class="hljs-annotation">@Override</span>
    <span class="hljs-keyword">public</span> LayoutParams <span class="hljs-title">generateLayoutParams</span>(AttributeSet attrs) {
        <span class="hljs-keyword">return</span> <span class="hljs-keyword">new</span> LayoutParams(getContext(), attrs);
    }

    <span class="hljs-annotation">@Override</span>
    <span class="hljs-keyword">protected</span> <span class="hljs-keyword">void</span> <span class="hljs-title">onMeasure</span>(<span class="hljs-keyword">int</span> widthMeasureSpec, <span class="hljs-keyword">int</span> heightMeasureSpec) {
        mHelper.adjustChildren(widthMeasureSpec, heightMeasureSpec);
        <span class="hljs-keyword">super</span>.onMeasure(widthMeasureSpec, heightMeasureSpec);
        <span class="hljs-keyword">if</span> (mHelper.handleMeasuredStateTooSmall()) {
            <span class="hljs-keyword">super</span>.onMeasure(widthMeasureSpec, heightMeasureSpec);
        }
    }

    <span class="hljs-annotation">@Override</span>
    <span class="hljs-keyword">protected</span> <span class="hljs-keyword">void</span> <span class="hljs-title">onLayout</span>(<span class="hljs-keyword">boolean</span> changed, <span class="hljs-keyword">int</span> left, <span class="hljs-keyword">int</span> top, <span class="hljs-keyword">int</span> right, <span class="hljs-keyword">int</span> bottom) {
        <span class="hljs-keyword">super</span>.onLayout(changed, left, top, right, bottom);
        mHelper.restoreOriginalParams();
    }

    <span class="hljs-keyword">public</span> <span class="hljs-keyword">static</span> <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">LayoutParams</span> <span class="hljs-keyword">extends</span> <span class="hljs-title">FrameLayout</span>.<span class="hljs-title">LayoutParams</span>
            <span class="hljs-keyword">implements</span> <span class="hljs-title">PercentLayoutHelper</span>.<span class="hljs-title">PercentLayoutParams</span> {</span>
        <span class="hljs-keyword">private</span> PercentLayoutHelper.PercentLayoutInfo mPercentLayoutInfo;

        <span class="hljs-keyword">public</span> <span class="hljs-title">LayoutParams</span>(Context c, AttributeSet attrs) {
            <span class="hljs-keyword">super</span>(c, attrs);
            mPercentLayoutInfo = PercentLayoutHelper.getPercentLayoutInfo(c, attrs);
        }
        <span class="hljs-comment">//省略了一些代码...</span>

        <span class="hljs-annotation">@Override</span>
        <span class="hljs-keyword">public</span> PercentLayoutHelper.PercentLayoutInfo <span class="hljs-title">getPercentLayoutInfo</span>() {
            <span class="hljs-keyword">return</span> mPercentLayoutInfo;
        }

        <span class="hljs-annotation">@Override</span>
        <span class="hljs-keyword">protected</span> <span class="hljs-keyword">void</span> <span class="hljs-title">setBaseAttributes</span>(TypedArray a, <span class="hljs-keyword">int</span> widthAttr, <span class="hljs-keyword">int</span> heightAttr) {
            PercentLayoutHelper.fetchWidthAndHeight(<span class="hljs-keyword">this</span>, a, widthAttr, heightAttr);
        }
    }
}</code><ul class="pre-numbering" style="display: block;"><li>1</li><li>2</li><li>3</li><li>4</li><li>5</li><li>6</li><li>7</li><li>8</li><li>9</li><li>10</li><li>11</li><li>12</li><li>13</li><li>14</li><li>15</li><li>16</li><li>17</li><li>18</li><li>19</li><li>20</li><li>21</li><li>22</li><li>23</li><li>24</li><li>25</li><li>26</li><li>27</li><li>28</li><li>29</li><li>30</li><li>31</li><li>32</li><li>33</li><li>34</li><li>35</li><li>36</li><li>37</li><li>38</li><li>39</li><li>40</li><li>41</li><li>42</li><li>43</li><li>44</li><li>45</li><li>46</li><li>47</li><li>48</li><li>49</li><li>50</li><li>51</li><li>52</li></ul>

代码是相当的短，可以看到PercentFrameLayout里面首先重写了generateLayoutParams方法，当然了，由于支持了一些新的layout_属性，那么肯定需要定义对应的LayoutParams。

（一）percent相关属性的获取

可以看到PercentFrameLayout.LayoutParams在原有的FrameLayout.LayoutParams基础上，实现了PercentLayoutHelper.PercentLayoutParams接口。

这个接口很简单，只有一个方法：

<code class="language-java hljs  has-numbering"><span class="hljs-keyword">public</span> <span class="hljs-class"><span class="hljs-keyword">interface</span> <span class="hljs-title">PercentLayoutParams</span> {</span>
        PercentLayoutInfo getPercentLayoutInfo();
    }</code><ul class="pre-numbering" style="display: block;"><li>1</li><li>2</li><li>3</li></ul>

而，这个方法的实现呢，也只有一行：return mPercentLayoutInfo;，那么这个mPercentLayoutInfo在哪完成赋值呢？

看PercentFrameLayout.LayoutParams的构造方法：

<code class="language-java hljs  has-numbering"><span class="hljs-keyword">public</span> <span class="hljs-title">LayoutParams</span>(Context c, AttributeSet attrs) {
            <span class="hljs-keyword">super</span>(c, attrs);
            mPercentLayoutInfo = PercentLayoutHelper.getPercentLayoutInfo(c, attrs);
        }</code><ul class="pre-numbering" style="display: block;"><li>1</li><li>2</li><li>3</li><li>4</li></ul>

可以看到，将attrs传入给getPercentLayoutInfo方法，那么不用说，这个方法的内部，肯定是获取自定义属性的值，然后将其封装到PercentLayoutInfo对象中，最后返回。

代码如下：

<code class="language-java hljs  has-numbering"><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);
        <span class="hljs-keyword">float</span> value = array.getFraction(R.styleable.PercentLayout_Layout_layout_widthPercent, <span class="hljs-number">1</span>, <span class="hljs-number">1</span>,
                -<span class="hljs-number">1</span>f);
        <span class="hljs-keyword">if</span> (value != -<span class="hljs-number">1</span>f) {
            <span class="hljs-keyword">if</span> (Log.isLoggable(TAG, Log.VERBOSE)) {
                Log.v(TAG, <span class="hljs-string">"percent width: "</span> + value);
            }
            info = info != <span class="hljs-keyword">null</span> ? info : <span class="hljs-keyword">new</span> PercentLayoutInfo();
            info.widthPercent = value;
        }
        value = array.getFraction(R.styleable.PercentLayout_Layout_layout_heightPercent, <span class="hljs-number">1</span>, <span class="hljs-number">1</span>, -<span class="hljs-number">1</span>f);
        <span class="hljs-keyword">if</span> (value != -<span class="hljs-number">1</span>f) {
            <span class="hljs-keyword">if</span> (Log.isLoggable(TAG, Log.VERBOSE)) {
                Log.v(TAG, <span class="hljs-string">"percent height: "</span> + value);
            }
            info = info != <span class="hljs-keyword">null</span> ? info : <span class="hljs-keyword">new</span> PercentLayoutInfo();
            info.heightPercent = value;
        }
        value = array.getFraction(R.styleable.PercentLayout_Layout_layout_marginPercent, <span class="hljs-number">1</span>, <span class="hljs-number">1</span>, -<span class="hljs-number">1</span>f);
        <span class="hljs-keyword">if</span> (value != -<span class="hljs-number">1</span>f) {
            <span class="hljs-keyword">if</span> (Log.isLoggable(TAG, Log.VERBOSE)) {
                Log.v(TAG, <span class="hljs-string">"percent margin: "</span> + value);
            }
            info = info != <span class="hljs-keyword">null</span> ? info : <span class="hljs-keyword">new</span> PercentLayoutInfo();
            info.leftMarginPercent = value;
            info.topMarginPercent = value;
            info.rightMarginPercent = value;
            info.bottomMarginPercent = value;
        }
        value = array.getFraction(R.styleable.PercentLayout_Layout_layout_marginLeftPercent, <span class="hljs-number">1</span>, <span class="hljs-number">1</span>,
                -<span class="hljs-number">1</span>f);
        <span class="hljs-keyword">if</span> (value != -<span class="hljs-number">1</span>f) {
            <span class="hljs-keyword">if</span> (Log.isLoggable(TAG, Log.VERBOSE)) {
                Log.v(TAG, <span class="hljs-string">"percent left margin: "</span> + value);
            }
            info = info != <span class="hljs-keyword">null</span> ? info : <span class="hljs-keyword">new</span> PercentLayoutInfo();
            info.leftMarginPercent = value;
        }
        value = array.getFraction(R.styleable.PercentLayout_Layout_layout_marginTopPercent, <span class="hljs-number">1</span>, <span class="hljs-number">1</span>,
                -<span class="hljs-number">1</span>f);
        <span class="hljs-keyword">if</span> (value != -<span class="hljs-number">1</span>f) {
            <span class="hljs-keyword">if</span> (Log.isLoggable(TAG, Log.VERBOSE)) {
                Log.v(TAG, <span class="hljs-string">"percent top margin: "</span> + value);
            }
            info = info != <span class="hljs-keyword">null</span> ? info : <span class="hljs-keyword">new</span> PercentLayoutInfo();
            info.topMarginPercent = value;
        }
        value = array.getFraction(R.styleable.PercentLayout_Layout_layout_marginRightPercent, <span class="hljs-number">1</span>, <span class="hljs-number">1</span>,
                -<span class="hljs-number">1</span>f);
        <span class="hljs-keyword">if</span> (value != -<span class="hljs-number">1</span>f) {
            <span class="hljs-keyword">if</span> (Log.isLoggable(TAG, Log.VERBOSE)) {
                Log.v(TAG, <span class="hljs-string">"percent right margin: "</span> + value);
            }
            info = info != <span class="hljs-keyword">null</span> ? info : <span class="hljs-keyword">new</span> PercentLayoutInfo();
            info.rightMarginPercent = value;
        }
        value = array.getFraction(R.styleable.PercentLayout_Layout_layout_marginBottomPercent, <span class="hljs-number">1</span>, <span class="hljs-number">1</span>,
                -<span class="hljs-number">1</span>f);
        <span class="hljs-keyword">if</span> (value != -<span class="hljs-number">1</span>f) {
            <span class="hljs-keyword">if</span> (Log.isLoggable(TAG, Log.VERBOSE)) {
                Log.v(TAG, <span class="hljs-string">"percent bottom margin: "</span> + value);
            }
            info = info != <span class="hljs-keyword">null</span> ? info : <span class="hljs-keyword">new</span> PercentLayoutInfo();
            info.bottomMarginPercent = value;
        }
        value = array.getFraction(R.styleable.PercentLayout_Layout_layout_marginStartPercent, <span class="hljs-number">1</span>, <span class="hljs-number">1</span>,
                -<span class="hljs-number">1</span>f);
        <span class="hljs-keyword">if</span> (value != -<span class="hljs-number">1</span>f) {
            <span class="hljs-keyword">if</span> (Log.isLoggable(TAG, Log.VERBOSE)) {
                Log.v(TAG, <span class="hljs-string">"percent start margin: "</span> + value);
            }
            info = info != <span class="hljs-keyword">null</span> ? info : <span class="hljs-keyword">new</span> PercentLayoutInfo();
            info.startMarginPercent = value;
        }
        value = array.getFraction(R.styleable.PercentLayout_Layout_layout_marginEndPercent, <span class="hljs-number">1</span>, <span class="hljs-number">1</span>,
                -<span class="hljs-number">1</span>f);
        <span class="hljs-keyword">if</span> (value != -<span class="hljs-number">1</span>f) {
            <span class="hljs-keyword">if</span> (Log.isLoggable(TAG, Log.VERBOSE)) {
                Log.v(TAG, <span class="hljs-string">"percent end margin: "</span> + value);
            }
            info = info != <span class="hljs-keyword">null</span> ? info : <span class="hljs-keyword">new</span> PercentLayoutInfo();
            info.endMarginPercent = value;
        }
        array.recycle();
        <span class="hljs-keyword">if</span> (Log.isLoggable(TAG, Log.DEBUG)) {
            Log.d(TAG, <span class="hljs-string">"constructed: "</span> + info);
        }
        <span class="hljs-keyword">return</span> info;
    }</code><ul class="pre-numbering" style="display: block;"><li>1</li><li>2</li><li>3</li><li>4</li><li>5</li><li>6</li><li>7</li><li>8</li><li>9</li><li>10</li><li>11</li><li>12</li><li>13</li><li>14</li><li>15</li><li>16</li><li>17</li><li>18</li><li>19</li><li>20</li><li>21</li><li>22</li><li>23</li><li>24</li><li>25</li><li>26</li><li>27</li><li>28</li><li>29</li><li>30</li><li>31</li><li>32</li><li>33</li><li>34</li><li>35</li><li>36</li><li>37</li><li>38</li><li>39</li><li>40</li><li>41</li><li>42</li><li>43</li><li>44</li><li>45</li><li>46</li><li>47</li><li>48</li><li>49</li><li>50</li><li>51</li><li>52</li><li>53</li><li>54</li><li>55</li><li>56</li><li>57</li><li>58</li><li>59</li><li>60</li><li>61</li><li>62</li><li>63</li><li>64</li><li>65</li><li>66</li><li>67</li><li>68</li><li>69</li><li>70</li><li>71</li><li>72</li><li>73</li><li>74</li><li>75</li><li>76</li><li>77</li><li>78</li><li>79</li><li>80</li><li>81</li><li>82</li><li>83</li><li>84</li><li>85</li><li>86</li><li>87</li><li>88</li><li>89</li><li>90</li><li>91</li><li>92</li></ul>

是不是和我们平时的取值很类似，所有的值最终封装到PercentLayoutInfo对象中。

ok，到此我们的属性获取就介绍完成，有了这些属性，是不是onMeasure里面要进行使用呢？

(二) onMeasue中重新计算child的尺寸

<code class="language-java hljs  has-numbering"><span class="hljs-annotation">@Override</span>
    <span class="hljs-keyword">protected</span> <span class="hljs-keyword">void</span> <span class="hljs-title">onMeasure</span>(<span class="hljs-keyword">int</span> widthMeasureSpec, <span class="hljs-keyword">int</span> heightMeasureSpec) {
        mHelper.adjustChildren(widthMeasureSpec, heightMeasureSpec);
        <span class="hljs-keyword">super</span>.onMeasure(widthMeasureSpec, heightMeasureSpec);
        <span class="hljs-keyword">if</span> (mHelper.handleMeasuredStateTooSmall()) {
            <span class="hljs-keyword">super</span>.onMeasure(widthMeasureSpec, heightMeasureSpec);
        }
    }</code><ul class="pre-numbering" style="display: block;"><li>1</li><li>2</li><li>3</li><li>4</li><li>5</li><li>6</li><li>7</li><li>8</li></ul>

可以看到onMeasure中的代码页很少，看来核心的代码都被封装在mHelper的方法中，我们直接看mHelper.adjustChildren方法。

<code class="language-java hljs  has-numbering"><span class="hljs-javadoc">/**
     * Iterates over children and changes their width and height to one calculated from percentage
     * values.
     *<span class="hljs-javadoctag"> @param</span> widthMeasureSpec Width MeasureSpec of the parent ViewGroup.
     *<span class="hljs-javadoctag"> @param</span> heightMeasureSpec Height MeasureSpec of the parent ViewGroup.
     */</span>
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">adjustChildren</span>(<span class="hljs-keyword">int</span> widthMeasureSpec, <span class="hljs-keyword">int</span> heightMeasureSpec) {
        <span class="hljs-comment">//...</span>
        <span class="hljs-keyword">int</span> widthHint = View.MeasureSpec.getSize(widthMeasureSpec);
        <span class="hljs-keyword">int</span> heightHint = View.MeasureSpec.getSize(heightMeasureSpec);
        <span class="hljs-keyword">for</span> (<span class="hljs-keyword">int</span> i = <span class="hljs-number">0</span>, N = mHost.getChildCount(); i < N; i++) {
            View view = mHost.getChildAt(i);
            ViewGroup.LayoutParams params = view.getLayoutParams();

            <span class="hljs-keyword">if</span> (params <span class="hljs-keyword">instanceof</span> PercentLayoutParams) {
                PercentLayoutInfo info =
                        ((PercentLayoutParams) params).getPercentLayoutInfo();
                <span class="hljs-keyword">if</span> (Log.isLoggable(TAG, Log.DEBUG)) {
                    Log.d(TAG, <span class="hljs-string">"using "</span> + info);
                }
                <span class="hljs-keyword">if</span> (info != <span class="hljs-keyword">null</span>) {
                    <span class="hljs-keyword">if</span> (params <span class="hljs-keyword">instanceof</span> ViewGroup.MarginLayoutParams) {
                        info.fillMarginLayoutParams((ViewGroup.MarginLayoutParams) params,
                                widthHint, heightHint);
                    } <span class="hljs-keyword">else</span> {
                        info.fillLayoutParams(params, widthHint, heightHint);
                    }
                }
            }
        }
    }
</code><ul class="pre-numbering" style="display: block;"><li>1</li><li>2</li><li>3</li><li>4</li><li>5</li><li>6</li><li>7</li><li>8</li><li>9</li><li>10</li><li>11</li><li>12</li><li>13</li><li>14</li><li>15</li><li>16</li><li>17</li><li>18</li><li>19</li><li>20</li><li>21</li><li>22</li><li>23</li><li>24</li><li>25</li><li>26</li><li>27</li><li>28</li><li>29</li><li>30</li><li>31</li><li>32</li></ul>

通过注释也能看出，此方法中遍历所有的孩子，通过百分比的属性重新设置其宽度和高度。

首先在widthHint、heightHint保存容器的宽、高，然后遍历所有的孩子，判断其LayoutParams是否是PercentLayoutParams类型，如果是，通过params.getPercentLayoutInfo拿出info对象。

是否还记得，上面的分析中，PercentLayoutInfo保存了percent相关属性的值。

如果info不为null，则判断是否需要处理margin；我们直接看fillLayoutParams方法（处理margin也是类似的）。

<code class="language-java hljs  has-numbering"> <span class="hljs-javadoc">/**
         * Fills {@code ViewGroup.LayoutParams} dimensions based on percentage values.
         */</span>
        <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-keyword">if</span> (widthPercent >= <span class="hljs-number">0</span>) {
                params.width = (<span class="hljs-keyword">int</span>) (widthHint * widthPercent);
            }
            <span class="hljs-keyword">if</span> (heightPercent >= <span class="hljs-number">0</span>) {
                params.height = (<span class="hljs-keyword">int</span>) (heightHint * heightPercent);
            }
            <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>);
            }
        }</code><ul class="pre-numbering" style="display: block;"><li>1</li><li>2</li><li>3</li><li>4</li><li>5</li><li>6</li><li>7</li><li>8</li><li>9</li><li>10</li><li>11</li><li>12</li><li>13</li><li>14</li><li>15</li><li>16</li><li>17</li><li>18</li><li>19</li></ul>

首先保存原本的width和height，然后重置params的width和height为(int) (widthHint * widthPercent)和(int) (heightHint * heightPercent);。

到此，其实我们的百分比转换就结束了，理论上就已经实现了对于百分比的支持，不过Google还考虑了一些细节。

我们回到onMeasure方法：

<code class="language-java hljs  has-numbering"><span class="hljs-annotation">@Override</span>
    <span class="hljs-keyword">protected</span> <span class="hljs-keyword">void</span> <span class="hljs-title">onMeasure</span>(<span class="hljs-keyword">int</span> widthMeasureSpec, <span class="hljs-keyword">int</span> heightMeasureSpec) {
        mHelper.adjustChildren(widthMeasureSpec, heightMeasureSpec);
        <span class="hljs-keyword">super</span>.onMeasure(widthMeasureSpec, heightMeasureSpec);
        <span class="hljs-keyword">if</span> (mHelper.handleMeasuredStateTooSmall()) {
            <span class="hljs-keyword">super</span>.onMeasure(widthMeasureSpec, heightMeasureSpec);
        }
    }</code><ul class="pre-numbering" style="display: block;"><li>1</li><li>2</li><li>3</li><li>4</li><li>5</li><li>6</li><li>7</li><li>8</li></ul>

下面还有个mHelper.handleMeasuredStateTooSmall的判断，也就是说，如果你设置的百分比，最终计算出来的MeasuredSize过小的话，会进行一些操作。
代码如下：

<code class="language-java hljs  has-numbering"><span class="hljs-keyword">public</span> <span class="hljs-keyword">boolean</span> <span class="hljs-title">handleMeasuredStateTooSmall</span>() {
        <span class="hljs-keyword">boolean</span> needsSecondMeasure = <span class="hljs-keyword">false</span>;
        <span class="hljs-keyword">for</span> (<span class="hljs-keyword">int</span> i = <span class="hljs-number">0</span>, N = mHost.getChildCount(); i < N; i++) {
            View view = mHost.getChildAt(i);
            ViewGroup.LayoutParams params = view.getLayoutParams();
            <span class="hljs-keyword">if</span> (Log.isLoggable(TAG, Log.DEBUG)) {
                Log.d(TAG, <span class="hljs-string">"should handle measured state too small "</span> + view + <span class="hljs-string">" "</span> + params);
            }
            <span class="hljs-keyword">if</span> (params <span class="hljs-keyword">instanceof</span> PercentLayoutParams) {
                PercentLayoutInfo info =
                        ((PercentLayoutParams) params).getPercentLayoutInfo();
                <span class="hljs-keyword">if</span> (info != <span class="hljs-keyword">null</span>) {
                    <span class="hljs-keyword">if</span> (shouldHandleMeasuredWidthTooSmall(view, info)) {
                        needsSecondMeasure = <span class="hljs-keyword">true</span>;
                        params.width = ViewGroup.LayoutParams.WRAP_CONTENT;
                    }
                    <span class="hljs-keyword">if</span> (shouldHandleMeasuredHeightTooSmall(view, info)) {
                        needsSecondMeasure = <span class="hljs-keyword">true</span>;
                        params.height = ViewGroup.LayoutParams.WRAP_CONTENT;
                    }
                }
            }
        }
        <span class="hljs-keyword">if</span> (Log.isLoggable(TAG, Log.DEBUG)) {
            Log.d(TAG, <span class="hljs-string">"should trigger second measure pass: "</span> + needsSecondMeasure);
        }
        <span class="hljs-keyword">return</span> needsSecondMeasure;
    }</code><ul class="pre-numbering" style="display: block;"><li>1</li><li>2</li><li>3</li><li>4</li><li>5</li><li>6</li><li>7</li><li>8</li><li>9</li><li>10</li><li>11</li><li>12</li><li>13</li><li>14</li><li>15</li><li>16</li><li>17</li><li>18</li><li>19</li><li>20</li><li>21</li><li>22</li><li>23</li><li>24</li><li>25</li><li>26</li><li>27</li><li>28</li></ul>

首先遍历所有的孩子，拿出孩子的layoutparams，如果是PercentLayoutParams实例，则取出info。如果info不为null，调用shouldHandleMeasuredWidthTooSmall判断：

<code class="language-java hljs  has-numbering"><span class="hljs-keyword">private</span> <span class="hljs-keyword">static</span> <span class="hljs-keyword">boolean</span> <span class="hljs-title">shouldHandleMeasuredWidthTooSmall</span>(View view, PercentLayoutInfo info) {
        <span class="hljs-keyword">int</span> state = ViewCompat.getMeasuredWidthAndState(view) & ViewCompat.MEASURED_STATE_MASK;
        <span class="hljs-keyword">return</span> state == ViewCompat.MEASURED_STATE_TOO_SMALL && info.widthPercent >= <span class="hljs-number">0</span> &&
                info.mPreservedParams.width == ViewGroup.LayoutParams.WRAP_CONTENT;
    }</code><ul class="pre-numbering" style="display: block;"><li>1</li><li>2</li><li>3</li><li>4</li><li>5</li></ul>

这里就是判断，如果你设置的measuredWidth或者measureHeight过小的话，并且你在布局文件中layout_w/h 设置的是WRAP_CONTENT的话，将params.width / height= ViewGroup.LayoutParams.WRAP_CONTENT，然后重新测量。

哈，onMeasure终于结束了~~~现在我觉得应该代码结束了吧，尺寸都设置好了，还需要干嘛么，but，你会发现onLayout也重写了，我们又不改变layout规则，在onLayout里面干什么毛线：

<code class="language-java hljs  has-numbering"><span class="hljs-annotation">@Override</span>
    <span class="hljs-keyword">protected</span> <span class="hljs-keyword">void</span> <span class="hljs-title">onLayout</span>(<span class="hljs-keyword">boolean</span> changed, <span class="hljs-keyword">int</span> left, <span class="hljs-keyword">int</span> top, <span class="hljs-keyword">int</span> right, <span class="hljs-keyword">int</span> bottom) {
        <span class="hljs-keyword">super</span>.onLayout(changed, left, top, right, bottom);
        mHelper.restoreOriginalParams();
    }</code><ul class="pre-numbering" style="display: block;"><li>1</li><li>2</li><li>3</li><li>4</li><li>5</li></ul>

继续看mHelper.restoreOriginalParams

<code class="language-java hljs  has-numbering"> <span class="hljs-javadoc">/**
     * Iterates over children and restores their original dimensions that were changed for
     * percentage values. Calling this method only makes sense if you previously called
     * {@link PercentLayoutHelper#adjustChildren(int, int)}.
     */</span>
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">restoreOriginalParams</span>() {
        <span class="hljs-keyword">for</span> (<span class="hljs-keyword">int</span> i = <span class="hljs-number">0</span>, N = mHost.getChildCount(); i < N; i++) {
            View view = mHost.getChildAt(i);
            ViewGroup.LayoutParams params = view.getLayoutParams();
            <span class="hljs-keyword">if</span> (Log.isLoggable(TAG, Log.DEBUG)) {
                Log.d(TAG, <span class="hljs-string">"should restore "</span> + view + <span class="hljs-string">" "</span> + params);
            }
            <span class="hljs-keyword">if</span> (params <span class="hljs-keyword">instanceof</span> PercentLayoutParams) {
                PercentLayoutInfo info =
                        ((PercentLayoutParams) params).getPercentLayoutInfo();
                <span class="hljs-keyword">if</span> (Log.isLoggable(TAG, Log.DEBUG)) {
                    Log.d(TAG, <span class="hljs-string">"using "</span> + info);
                }
                <span class="hljs-keyword">if</span> (info != <span class="hljs-keyword">null</span>) {
                    <span class="hljs-keyword">if</span> (params <span class="hljs-keyword">instanceof</span> ViewGroup.MarginLayoutParams) {
                        info.restoreMarginLayoutParams((ViewGroup.MarginLayoutParams) params);
                    } <span class="hljs-keyword">else</span> {
                        info.restoreLayoutParams(params);
                    }
                }
            }
        }
    }
</code><ul class="pre-numbering" style="display: block;"><li>1</li><li>2</li><li>3</li><li>4</li><li>5</li><li>6</li><li>7</li><li>8</li><li>9</li><li>10</li><li>11</li><li>12</li><li>13</li><li>14</li><li>15</li><li>16</li><li>17</li><li>18</li><li>19</li><li>20</li><li>21</li><li>22</li><li>23</li><li>24</li><li>25</li><li>26</li><li>27</li><li>28</li><li>29</li></ul>

噗，原来是重新恢复原本的尺寸值，也就是说onMeasure里面的对值进行了改变，测量完成后。在这个地方，将值又恢复成如果布局文件中的值，上面写的都是0。恢复很简单：

<code class="language-java hljs  has-numbering">
<span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">restoreLayoutParams</span>(ViewGroup.LayoutParams params) {
            params.width = mPreservedParams.width;
            params.height = mPreservedParams.height;
        }</code><ul class="pre-numbering" style="display: block;"><li>1</li><li>2</li><li>3</li><li>4</li><li>5</li></ul>

你应该没有忘在哪存的把~忘了的话，麻烦Ctrl+F ‘mPreservedParams.width’ 。

也就是说，你去打印上面写法，布局文件中view的v.getLayoutParams().width，这个值应该是0。

这里感觉略微不爽~这个0没撒用处呀，还不如不重置~~

好了，到此就分析完了，其实主要就几个步骤：

LayoutParams中属性的获取onMeasure中，改变params.width为百分比计算结果，测量如果测量值过小且设置的w/h是wrap_content，重新测量onLayout中，重置params.w/h为布局文件中编写的值

可以看到，有了RelativeLayout、FrameLayout的扩展，竟然没有LinearLayout几个意思。好在，我们的核心代码都由PercentLayoutHelper封装了，自己扩展下LinearLayout也不复杂。

三、实现PercentLinearlayout

可能有人会说，有了weight呀，但是weight能做到宽、高同时百分比赋值嘛？

好了，代码很简单，如下：

（一）PercentLinearLayout

<code class="language-java hljs  has-numbering"><span class="hljs-keyword">package</span> com.juliengenoud.percentsamples;

<span class="hljs-keyword">import</span> android.content.Context;
<span class="hljs-keyword">import</span> android.content.res.TypedArray;
<span class="hljs-keyword">import</span> android.support.percent.PercentLayoutHelper;
<span class="hljs-keyword">import</span> android.util.AttributeSet;
<span class="hljs-keyword">import</span> android.view.ViewGroup;
<span class="hljs-keyword">import</span> android.widget.LinearLayout;

<span class="hljs-javadoc">/**
 * Created by zhy on 15/6/30.
 */</span>
<span class="hljs-keyword">public</span> <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">PercentLinearLayout</span> <span class="hljs-keyword">extends</span> <span class="hljs-title">LinearLayout</span>
{</span>

    <span class="hljs-keyword">private</span> PercentLayoutHelper mPercentLayoutHelper;

    <span class="hljs-keyword">public</span> <span class="hljs-title">PercentLinearLayout</span>(Context context, AttributeSet attrs)
    {
        <span class="hljs-keyword">super</span>(context, attrs);

        mPercentLayoutHelper = <span class="hljs-keyword">new</span> PercentLayoutHelper(<span class="hljs-keyword">this</span>);
    }

    <span class="hljs-annotation">@Override</span>
    <span class="hljs-keyword">protected</span> <span class="hljs-keyword">void</span> <span class="hljs-title">onMeasure</span>(<span class="hljs-keyword">int</span> widthMeasureSpec, <span class="hljs-keyword">int</span> heightMeasureSpec)
    {
        mPercentLayoutHelper.adjustChildren(widthMeasureSpec, heightMeasureSpec);
        <span class="hljs-keyword">super</span>.onMeasure(widthMeasureSpec, heightMeasureSpec);
        <span class="hljs-keyword">if</span> (mPercentLayoutHelper.handleMeasuredStateTooSmall())
        {
            <span class="hljs-keyword">super</span>.onMeasure(widthMeasureSpec, heightMeasureSpec);
        }
    }

    <span class="hljs-annotation">@Override</span>
    <span class="hljs-keyword">protected</span> <span class="hljs-keyword">void</span> <span class="hljs-title">onLayout</span>(<span class="hljs-keyword">boolean</span> changed, <span class="hljs-keyword">int</span> l, <span class="hljs-keyword">int</span> t, <span class="hljs-keyword">int</span> r, <span class="hljs-keyword">int</span> b)
    {
        <span class="hljs-keyword">super</span>.onLayout(changed, l, t, r, b);
        mPercentLayoutHelper.restoreOriginalParams();
    }

    <span class="hljs-annotation">@Override</span>
    <span class="hljs-keyword">public</span> LayoutParams <span class="hljs-title">generateLayoutParams</span>(AttributeSet attrs)
    {
        <span class="hljs-keyword">return</span> <span class="hljs-keyword">new</span> LayoutParams(getContext(), attrs);
    }

    <span class="hljs-keyword">public</span> <span class="hljs-keyword">static</span> <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">LayoutParams</span> <span class="hljs-keyword">extends</span> <span class="hljs-title">LinearLayout</span>.<span class="hljs-title">LayoutParams</span>
            <span class="hljs-keyword">implements</span> <span class="hljs-title">PercentLayoutHelper</span>.<span class="hljs-title">PercentLayoutParams</span>
    {</span>
        <span class="hljs-keyword">private</span> PercentLayoutHelper.PercentLayoutInfo mPercentLayoutInfo;

        <span class="hljs-keyword">public</span> <span class="hljs-title">LayoutParams</span>(Context c, AttributeSet attrs)
        {
            <span class="hljs-keyword">super</span>(c, attrs);
            mPercentLayoutInfo = PercentLayoutHelper.getPercentLayoutInfo(c, attrs);
        }

        <span class="hljs-annotation">@Override</span>
        <span class="hljs-keyword">public</span> PercentLayoutHelper.PercentLayoutInfo <span class="hljs-title">getPercentLayoutInfo</span>()
        {
            <span class="hljs-keyword">return</span> mPercentLayoutInfo;
        }

        <span class="hljs-annotation">@Override</span>
        <span class="hljs-keyword">protected</span> <span class="hljs-keyword">void</span> <span class="hljs-title">setBaseAttributes</span>(TypedArray a, <span class="hljs-keyword">int</span> widthAttr, <span class="hljs-keyword">int</span> heightAttr)
        {
            PercentLayoutHelper.fetchWidthAndHeight(<span class="hljs-keyword">this</span>, a, widthAttr, heightAttr);
        }

        <span class="hljs-keyword">public</span> <span class="hljs-title">LayoutParams</span>(<span class="hljs-keyword">int</span> width, <span class="hljs-keyword">int</span> height) {
            <span class="hljs-keyword">super</span>(width, height);
        }

        <span class="hljs-keyword">public</span> <span class="hljs-title">LayoutParams</span>(ViewGroup.LayoutParams source) {
            <span class="hljs-keyword">super</span>(source);
        }

        <span class="hljs-keyword">public</span> <span class="hljs-title">LayoutParams</span>(MarginLayoutParams source) {
            <span class="hljs-keyword">super</span>(source);
        }

    }

}

</code><ul class="pre-numbering" style="display: block;"><li>1</li><li>2</li><li>3</li><li>4</li><li>5</li><li>6</li><li>7</li><li>8</li><li>9</li><li>10</li><li>11</li><li>12</li><li>13</li><li>14</li><li>15</li><li>16</li><li>17</li><li>18</li><li>19</li><li>20</li><li>21</li><li>22</li><li>23</li><li>24</li><li>25</li><li>26</li><li>27</li><li>28</li><li>29</li><li>30</li><li>31</li><li>32</li><li>33</li><li>34</li><li>35</li><li>36</li><li>37</li><li>38</li><li>39</li><li>40</li><li>41</li><li>42</li><li>43</li><li>44</li><li>45</li><li>46</li><li>47</li><li>48</li><li>49</li><li>50</li><li>51</li><li>52</li><li>53</li><li>54</li><li>55</li><li>56</li><li>57</li><li>58</li><li>59</li><li>60</li><li>61</li><li>62</li><li>63</li><li>64</li><li>65</li><li>66</li><li>67</li><li>68</li><li>69</li><li>70</li><li>71</li><li>72</li><li>73</li><li>74</li><li>75</li><li>76</li><li>77</li><li>78</li><li>79</li><li>80</li><li>81</li><li>82</li><li>83</li><li>84</li><li>85</li><li>86</li><li>87</li><li>88</li><li>89</li><li>90</li><li>91</li></ul>

如果你详细看了上面的源码分析，这个代码是不是没撒解释的了~

（二）测试布局

<code class="language-xml hljs  has-numbering"><span class="hljs-pi"><?xml version="1.0" encoding="utf-8"?></span>

<span class="hljs-tag"><<span class="hljs-title">com.juliengenoud.percentsamples.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">"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">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:text</span>=<span class="hljs-value">"width:60%,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">"5%"</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">"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:textColor</span>=<span class="hljs-value">"#ffffff"</span>
        <span class="hljs-attribute">android:text</span>=<span class="hljs-value">"width:70%,height:10%"</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">"width:80%,height:15%"</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_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">"10%"</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">com.juliengenoud.percentsamples.PercentLinearLayout</span>></span>

</code><ul class="pre-numbering" style="display: block;"><li>1</li><li>2</li><li>3</li><li>4</li><li>5</li><li>6</li><li>7</li><li>8</li><li>9</li><li>10</li><li>11</li><li>12</li><li>13</li><li>14</li><li>15</li><li>16</li><li>17</li><li>18</li><li>19</li><li>20</li><li>21</li><li>22</li><li>23</li><li>24</li><li>25</li><li>26</li><li>27</li><li>28</li><li>29</li><li>30</li><li>31</li><li>32</li><li>33</li><li>34</li><li>35</li><li>36</li><li>37</li><li>38</li><li>39</li><li>40</li><li>41</li><li>42</li><li>43</li><li>44</li><li>45</li><li>46</li><li>47</li><li>48</li><li>49</li><li>50</li><li>51</li><li>52</li><li>53</li><li>54</li><li>55</li><li>56</li><li>57</li><li>58</li><li>59</li><li>60</li><li>61</li><li>62</li><li>63</li><li>64</li><li>65</li><li>66</li></ul>

我们纵向排列的几个TextView，分别设置宽/高都为百分比，且之间的间隔为5%p。

(三)效果图

ok，到此，我们使用、源码分析、扩展PercentLinearLayout就结束了。

添加PercentLinearLayout后的地址：点击查看

扩展下载:android-percent-support-extend 包含android studio, eclipse项目，以及上述源码。

~~have a nice day ~~

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