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一，百分比布局库android-percent-support介绍
百分比布局库中提供了两种布局可以设置百分比：PercentRelativeLayout、PercentFrameLayout。
这两个百分比布局都有以下九个布局属性，值都是用百分比来表示宽度、高度、margin值，使用时候需要父布局为百分比布局，child控件才可以使用这九个布局属性：
app:layout_heightPercent
app:layout_widthPercent
app:layout_marginPercent
app:layout_marginTopPercent
app:layout_marginBottomPercent
app:layout_marginLeftPercent
app:layout_marginRightPercent
app:layout_marginStartPercent
app: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。
二，百分比布局使用
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：
compile 'com.android.support:percent:22.2.0'
1
(一) PercentFrameLayout
<?xml version="1.0" encoding="utf-8"?>
<android.support.percent.PercentFrameLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_gravity="left|top"
android:background="#44ff0000"
android:text="width:30%,height:20%"
app:layout_heightPercent="20%"
android:gravity="center"
app:layout_widthPercent="30%"/>
<TextView
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_gravity="right|top"
android:gravity="center"
android:background="#4400ff00"
android:text="width:70%,height:20%"
app:layout_heightPercent="20%"
app:layout_widthPercent="70%"/>
<TextView
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_gravity="bottom"
android:background="#770000ff"
android:text="width:100%,height:10%"
android:gravity="center"
app:layout_heightPercent="10%"
app:layout_widthPercent="100%"/>
</android.support.percent.PercentFrameLayout>
3个TextView，很简单，直接看效果图：
(二) PercentRelativeLayout
<?xml version="1.0" encoding="utf-8"?>
<android.support.percent.PercentRelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:clickable="true">
<TextView
android:id="@+id/row_one_item_one"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_alignParentTop="true"
android:background="#7700ff00"
android:text="w:70%,h:20%"
android:gravity="center"
app:layout_heightPercent="20%"
app:layout_widthPercent="70%"/>
<TextView
android:id="@+id/row_one_item_two"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_toRightOf="@+id/row_one_item_one"
android:background="#396190"
android:text="w:30%,h:20%"
app:layout_heightPercent="20%"
android:gravity="center"
app:layout_widthPercent="30%"/>
<ImageView
android:id="@+id/row_two_item_one"
android:layout_width="match_parent"
android:layout_height="0dp"
android:src="@drawable/tangyan"
android:scaleType="centerCrop"
android:layout_below="@+id/row_one_item_one"
android:background="#d89695"
app:layout_heightPercent="70%"/>
<TextView
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_below="@id/row_two_item_one"
android:background="#770000ff"
android:gravity="center"
android:text="width:100%,height:10%"
app:layout_heightPercent="10%"
app:layout_widthPercent="100%"/>
</android.support.percent.PercentRelativeLayout>
(三) 使用注意
其实PercentRelativeLayout 和PercentFrameLayout就是多了九个布局属性的RelativeLayout 和FrameLayout，用法完全和这两个布局一样，不过只有父布局是百分比布局（PercentRelativeLayout和PercentFrameLayout ）的时候，child才能使用百分比布局属性进行布局，否则无效，如：
<android.support.percent.PercentRelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<Button
android:id="@+id/button"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:text="width=50%"
app:layout_widthPercent="50%" />
</LinearLayout>
</android.support.percent.PercentRelativeLayout>
这样设置Button的宽度并不会是父布局宽度的一半，因为child用百分比只对父布局是百分比布局才有效。三、实现PercentLinearlayout
(一) PercentLinearLayout
package com.juliengenoud.percentsamples;
import android.content.Context;
import android.content.res.TypedArray;
import android.support.percent.PercentLayoutHelper;
import android.util.AttributeSet;
import android.view.ViewGroup;
import android.widget.LinearLayout;
/**
* Created by zhy on 15/6/30.
*/
public class PercentLinearLayout extends LinearLayout
{
private PercentLayoutHelper mPercentLayoutHelper;
public PercentLinearLayout(Context context, AttributeSet attrs)
{
super(context, attrs);
mPercentLayoutHelper = new PercentLayoutHelper(this);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
{
mPercentLayoutHelper.adjustChildren(widthMeasureSpec, heightMeasureSpec);
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
if (mPercentLayoutHelper.handleMeasuredStateTooSmall())
{
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b)
{
super.onLayout(changed, l, t, r, b);
mPercentLayoutHelper.restoreOriginalParams();
}
@Override
public LayoutParams generateLayoutParams(AttributeSet attrs)
{
return new LayoutParams(getContext(), attrs);
}
public static class LayoutParams extends LinearLayout.LayoutParams
implements PercentLayoutHelper.PercentLayoutParams
{
private PercentLayoutHelper.PercentLayoutInfo mPercentLayoutInfo;
public LayoutParams(Context c, AttributeSet attrs)
{
super(c, attrs);
mPercentLayoutInfo = PercentLayoutHelper.getPercentLayoutInfo(c, attrs);
}
@Override
public PercentLayoutHelper.PercentLayoutInfo getPercentLayoutInfo()
{
return mPercentLayoutInfo;
}
@Override
protected void setBaseAttributes(TypedArray a, int widthAttr, int heightAttr)
{
PercentLayoutHelper.fetchWidthAndHeight(this, a, widthAttr, heightAttr);
}
public LayoutParams(int width, int height) {
super(width, height);
}
public LayoutParams(ViewGroup.LayoutParams source) {
super(source);
}
public LayoutParams(MarginLayoutParams source) {
super(source);
}
}
}
(二) 布局使用
<?xml version="1.0" encoding="utf-8"?>
<com.juliengenoud.percentsamples.PercentLinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<TextView
android:layout_width="0dp"
android:layout_height="0dp"
android:background="#ff44aacc"
android:text="width:60%,height:5%"
android:textColor="#ffffff"
app:layout_heightPercent="5%"
app:layout_marginBottomPercent="5%"
app:layout_widthPercent="60%"/>
<TextView
android:layout_width="0dp"
android:layout_height="0dp"
android:background="#ff4400cc"
android:gravity="center"
android:textColor="#ffffff"
android:text="width:70%,height:10%"
app:layout_heightPercent="10%"
app:layout_marginBottomPercent="5%"
app:layout_widthPercent="70%"/>
<TextView
android:layout_width="0dp"
android:layout_height="0dp"
android:background="#ff44aacc"
android:gravity="center"
android:text="width:80%,height:15%"
android:textColor="#ffffff"
app:layout_heightPercent="15%"
app:layout_marginBottomPercent="5%"
app:layout_widthPercent="80%"/>
<TextView
android:layout_width="0dp"
android:layout_height="0dp"
android:background="#ff4400cc"
android:gravity="center"
android:text="width:90%,height:5%"
android:textColor="#ffffff"
app:layout_heightPercent="20%"
app:layout_marginBottomPercent="10%"
app:layout_widthPercent="90%"/>
<TextView
android:layout_width="match_parent"
android:layout_height="0dp"
android:background="#ff44aacc"
android:gravity="center"
android:text="width:100%,height:25%"
android:textColor="#ffffff"
app:layout_heightPercent="25%"
app:layout_marginBottomPercent="5%"
/>
</com.juliengenoud.percentsamples.PercentLinearLayout>
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。
四，固定比例属性 layout_aspectRatio
注意：layout_aspectRatio属性需要在23.3.0版本以上才能使用
详细解释请见：http://blog.csdn.net/zcn596785154/article/details/76855499
PercentLayout是百分比控件, 使用百分比属性创建控件. 除了常用的百分比, 也可以使用固定比例进行布局(aspect ratio)
PercentLayout布局, 提供宽度和比例, 自动适配高度.
<android.support.percent.PercentRelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/main_text">
<ImageView
android:layout_width="0dp"
android:layout_height="0dp"
android:background="#FF1493"
app:layout_aspectRatio="@fraction/header_aspectRatio"
app:layout_widthPercent="50%"/>
</android.support.percent.PercentRelativeLayout>
比例的资源文件, fractions.xml.
<resources>
<item name="header_aspectRatio" type="fraction">178%</item>
</resources>
178%的含义是16:9. //宽：高
文章参考：
Android 百分比布局库(percent-support-lib) 解析与扩展
PercentLayout的固定比例
Android百分比布局支持库（android-percent-support）