Android 百分比布局讲解

1 前沿

android 推出了百分比布局，有了这个布局我们按照百分比来分配屏幕。大家是不是听了很激动？下面我们来慢慢讲解。

2 控件介绍

2.1 控件介绍

我们来看一下这几个百分比控件：

1. PercentRelativeLayout2. PercentFrameLayout.

它们分别继承了FrameLayout和RelativeLayout两个容器类。大家可能奇怪为什么没有PercentLinearLayout控件呢？这个android确实没给出，但是我们可以自己做一个嘛！

2.2 支持的属性

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

上面这些是百分比宽度和margin属性，具体使用请继续看。

3 使用步骤

1. 在build.gradle添加：

    compile 'com.android.support:percent:22.2.0'

2. 使用控件

<?xml version="1.0" encoding="utf-8"?><android.support.percent.PercentRelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    xmlns:app="http://schemas.android.com/apk/res-auto"    android:orientation="vertical">    <Button        android:id="@+id/button1"        android:text="左按钮"        android:background="#FBAFB0"        android:layout_alignParentLeft="true"        android:layout_width="0dp"        android:layout_height="0dp"        app:layout_heightPercent="100%"        app:layout_widthPercent="70%"/>         />    <Button        android:id="@+id/button2"        android:text="右按钮"        android:background="#A5F4AF"        android:layout_alignParentRight="true"        android:layout_width="0dp"        android:layout_height="0dp"        app:layout_heightPercent="100%"        app:layout_widthPercent="30%"        /></android.support.percent.PercentRelativeLayout>

3. 效果图

是不是很简单啊。下面我们再自己做一个PercentLinearLayout.

4 PercentLinearLayout代码

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 Yyd on 2017-01-09. */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);        }    }}

5 结尾

注：本文参照鸿洋大神写的文章，因源码我还没有研究明白，所以只记录如何使用。等我研究明白再补充。

6 参考文档

1.Android 百分比布局库(percent-support-lib) 解析与扩展
2.PercentRelativeLayout 源码解析