ReactNative与Android中的屏幕适配

2019-11-09 15:31:52

字体：大中小

来源：转载

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前言：从开始接触rn到现在终于能写出点东西了，的确得为自己好好地点个赞，不管咋样，学习还是得继续啊，废话少说了，在rn中我们也需要对屏幕进行适配，但是rn中的适配貌似比android原生容易很多（不得佩服facebook那些大神哈，对android原生控件封装的太屌！）。

我们先看看rn中的屏幕适配（作为一个android程序员去做rn确实比ios程序员考虑的东西多一点点哈，嘻嘻～～）：结合android的一些适配经验，我在rn中也封装了一个工具类 ScreenUtils.js：

/** * 屏幕工具类 * ui设计基准,iphone 6 * width:750 * height:1334 */var ReactNative = require('react-native');var Dimensions = require('Dimensions');export var screenW = Dimensions.get('window').width;export var screenH = Dimensions.get('window').height;var fontScale = ReactNative.PixelRatio.getFontScale();export var pixelRatio = ReactNative.PixelRatio.get();const r2=2;const w2 = 750/r2;``const h2 = 1334/r2;/** * 设置text为sp * @param size sp * @returns {Number} dp */export const DEFAULT_DENSITY=2;export function setSpText(size:Number) { var scaleWidth = screenW / w2; var scaleHeight = screenH / h2; var scale = Math.min(scaleWidth, scaleHeight); size = Math.round((size * scale + 0.5) * pixelRatio / fontScale); return size;}/** * 屏幕适配,缩放size * @param size * @returns {Number} * @constructor */export function scaleSize(size:Number) { var scaleWidth = screenW / w2; var scaleHeight = screenH / h2; var scale = Math.min(scaleWidth, scaleHeight); size = Math.round((size * scale + 0.5)); return size/DEFAULT_DENSITY;}

搞过rn的童鞋知道，rn中直接写宽高都是dp的，所以我们要以一个美工设计的ui基准来计算我们的宽高，数学不好哈，不过大概是这样的：我们先定义好ui的设计基准：

然后获取到我们自己手机的屏幕宽高，生成一个百分比，然后算出在iphone6上的100px，在我们手机上是多少px，最后转换成dp设置在在我们布局的style中：

const styles = StyleSheet.create({ container: { backgroundColor: 'white', justifyContent: 'space-between', flexDirection: 'row', paddingTop: ScreenUtils.scaleSize(22), paddingBottom: ScreenUtils.scaleSize(22), paddingRight: ScreenUtils.scaleSize(12), paddingLeft: ScreenUtils.scaleSize(12), alignItems: 'center' },});

好啦～！！，rn上的适配就完啦，是不是soeasy呢？？？

但是在android原生中，我们写布局大多数都是在xml中写的，所以我们在写布局的时候，压根就不知道我要运行在什么手机上，所以android官方建议我们使用dp啊，然后建很多layout文件啊，很多value文件啊，是的！我个人也是比较推崇官方的做法的，效率高，清晰明了，好啦！！除了android官方说的那种方法，我们是否也可以像rn一样运行后再重新算出百分比，然后再布局呢？答案是肯定的，因为rn就是一个例子，它也是对原生控件封装过的，所以才能用js轻易控制，在此之前鸿洋大神也对百分比布局做了封装，也对齐做了很详细的解析了，先贴上大神的博客链接： [http://blog.csdn.net/lmj623565791/article/details/46767825](http://blog.csdn.net/lmj623565791/article/details/46767825

好啦！我们今天要做的也就是在百分比布局的基础上简单封装下，然后使得其能够像rn一样，直接写上美工标的px就能完美适配大部分手机了。

先上张运行好的效果图（效果还是很不错的！）：

布局文件：

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:id="@+id/activity_main" android:layout_width="match_parent" android:layout_height="match_parent" android:background="#ffffff" tools:context="com.example.leo.textdemo.MainActivity"> <com.yasin.px_percent_layout.PercentLinearLayout android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical"> <TextView android:layout_width="0dp" android:layout_height="0dp" app:layout_widthPercent="10%w" app:layout_heightPercent="10%h" android:text="10%w,10%h" android:background="#ff0000" android:textColor="#fff" /> <TextView android:layout_width="0dp" android:layout_height="0dp" app:layout_widthPercent="20%sw" app:layout_heightPercent="20%sh" android:text="屏幕宽的20%sw,屏幕高的20%sh" android:background="#ffff00" android:textColor="#ff00" /> <TextView android:layout_width="0dp" android:layout_height="0dp" app:layout_widthPercent="200px" app:layout_heightPercent="200px" android:text="iphone6为基准的宽：200px，高：200px" android:background="#0000ff" android:textColor="#fff" /> <TextView android:layout_width="0dp" android:layout_height="0dp" app:layout_widthPercent="375px" app:layout_heightPercent="375px" android:text="iphone6为基准的宽：370px，高：370px,textsize为28px" android:background="#00ff00" app:layout_textSizePercent="28px" android:textColor="#ff00" /> </com.yasin.px_percent_layout.PercentLinearLayout></RelativeLayout>

这里写图片描述

先走一遍百分比布，看它到底是咋实现适配的(以下是来自鸿洋大神封装过后的代码，我就直接拿走解析了，嘻嘻！！)：

PercentLinearLayout.java:

package com.yasin.px_percent_layout;import android.app.Activity;import android.content.Context;import android.content.res.TypedArray;import android.util.AttributeSet;import android.util.DisplayMetrics;import android.view.ViewGroup;import android.view.WindowManager;import android.widget.LinearLayout;import android.widget.ScrollView;public class PercentLinearLayout extends LinearLayout { PRivate static final String TAG = "PercentLinearLayout"; private PercentLayoutHelper mPercentLayoutHelper; public PercentLinearLayout(Context context, AttributeSet attrs) { super(context, attrs); mPercentLayoutHelper = new PercentLayoutHelper(this); } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { int heightSize = MeasureSpec.getSize(heightMeasureSpec); int heightMode = MeasureSpec.getMode(heightMeasureSpec); int tmpHeightMeasureSpec = MeasureSpec.makeMeasureSpec(heightSize, heightMode); int widthSize = MeasureSpec.getSize(widthMeasureSpec); int widthMode = MeasureSpec.getMode(widthMeasureSpec); int tmpWidthMeasureSpec = MeasureSpec.makeMeasureSpec(widthSize, widthMode); //fixed scrollview height problems if (heightMode == MeasureSpec.UNSPECIFIED && getParent() != null && (getParent() instanceof ScrollView)) { int baseHeight = 0; Context context = getContext(); if (context instanceof Activity) { Activity act = (Activity) context; int measuredHeight = act.findViewById(android.R.id.content).getMeasuredHeight(); baseHeight = measuredHeight; } else { baseHeight = getScreenHeight(); } tmpHeightMeasureSpec = MeasureSpec.makeMeasureSpec(baseHeight, heightMode); } mPercentLayoutHelper.adjustChildren(tmpWidthMeasureSpec, tmpHeightMeasureSpec); super.onMeasure(widthMeasureSpec, heightMeasureSpec); if (mPercentLayoutHelper.handleMeasuredStateTooSmall()) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); } } private int getScreenHeight() { WindowManager wm = (WindowManager) getContext().getSystemService(Context.WINDOW_SERVICE); DisplayMetrics outMetrics = new DisplayMetrics(); wm.getDefaultDisplay().getMetrics(outMetrics); return outMetrics.heightPixels; } @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); } }}

代码不要太简单哈，就在构造方法中创建了一个mPercentLayoutHelper：

public PercentLinearLayout(Context context, AttributeSet attrs) { super(context, attrs); mPercentLayoutHelper = new PercentLayoutHelper(this); }

我们待会再来说这个PercentLayoutHelper，

然后就是创建了一个自己的LayoutParams：

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); } }

其中也咩有啥代码，创建了一个PercentLayoutInfo。

然后核心代码就是onMeasure方法里面了：

mPercentLayoutHelper.adjustChildren(tmpWidthMeasureSpec, tmpHeightMeasureSpec);

核心也就这一句。

终结下来就是： 1、先获取到我们在布局文件中定义的属性：

app:layout_widthPercent="10%w" app:layout_heightPercent="10%h" .......

2、然后把获取到的属性封装进一个叫PercentLayoutInfo的类中：

public LayoutParams(Context c, AttributeSet attrs) { super(c, attrs); mPercentLayoutInfo = PercentLayoutHelper.getPercentLayoutInfo(c, attrs); }

3、在onMeasure方法中根据传进的属性对子控件进行重置大小：

@Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { int heightSize = MeasureSpec.getSize(heightMeasureSpec); int heightMode = MeasureSpec.getMode(heightMeasureSpec); int tmpHeightMeasureSpec = MeasureSpec.makeMeasureSpec(heightSize, heightMode); int widthSize = MeasureSpec.getSize(widthMeasureSpec); int widthMode = MeasureSpec.getMode(widthMeasureSpec); int tmpWidthMeasureSpec = MeasureSpec.makeMeasureSpec(widthSize, widthMode); //fixed scrollview height problems if (heightMode == MeasureSpec.UNSPECIFIED && getParent() != null && (getParent() instanceof ScrollView)) { int baseHeight = 0; Context context = getContext(); if (context instanceof Activity) { Activity act = (Activity) context; int measuredHeight = act.findViewById(android.R.id.content).getMeasuredHeight(); baseHeight = measuredHeight; } else { baseHeight = getScreenHeight(); } tmpHeightMeasureSpec = MeasureSpec.makeMeasureSpec(baseHeight, heightMode); } mPercentLayoutHelper.adjustChildren(tmpWidthMeasureSpec, tmpHeightMeasureSpec); super.onMeasure(widthMeasureSpec, hei } }

看完是不是觉得很简单呢？是的，本来就不难哈，我们接着往下看：

先看看它是咋拿到我们在布局文件中写的属性的（怎么封装）：

public static PercentLayoutInfo getPercentLayoutInfo(Context context, AttributeSet attrs) { PercentLayoutInfo info = null; TypedArray array = context.obtainStyledAttributes(attrs, R.styleable.PercentLayout_Layout); info = setWidthAndHeightVal(array, info); info = setMarginRelatedVal(array, info); info = setTextSizeSupportVal(array, info); info = setMinMaxWidthHeightRelatedVal(array, info); info = setPaddingRelatedVal(array, info); array.recycle(); if (Log.isLoggable(TAG, Log.DEBUG)) { Log.d(TAG, "constructed: " + info); } return info; }

获取TypedArray数组中的数据（我们就只看setWidthAndHeightVal代码了）：

private static PercentLayoutInfo setWidthAndHeightVal(TypedArray array, PercentLayoutInfo info) { PercentLayoutInfo.PercentVal percentVal = getPercentVal(array, R.styleable.PercentLayout_Layout_layout_widthPercent, true); if (percentVal != null) { if (Log.isLoggable(TAG, Log.VERBOSE)) { Log.v(TAG, "percent width: " + percentVal.percent); } info = checkForInfoExists(info); info.widthPercent = percentVal; } percentVal = getPercentVal(array, R.styleable.PercentLayout_Layout_layout_heightPercent, false); if (percentVal != null) { if (Log.isLoggable(TAG, Log.VERBOSE)) { Log.v(TAG, "percent height: " + percentVal.percent); } info = checkForInfoExists(info); info.heightPercent = percentVal; } return info; }

获取到heightPercent跟widthPercent信息然后赋给info对象，没啥好看的，重点看看咋获取到的widthPercent信息：

private static PercentLayoutInfo.PercentVal getPercentVal(TypedArray array, int index, boolean baseWidth) { String sizeStr = array.getString(index); PercentLayoutInfo.PercentVal percentVal = getPercentVal(sizeStr, baseWidth); return percentVal; }

也没啥看的（继续往下走）：

private static PercentLayoutInfo.PercentVal getPercentVal(String percentStr, boolean isOnWidth) { //valid param if (percentStr == null) { return null; } Pattern p = Pattern.compile(REGEX_PERCENT); Matcher matcher = p.matcher(percentStr); if (TextUtils.isEmpty(percentStr) || (!matcher.matches() && !(percentStr.toLowerCase().endsWith("px")))) { throw new RuntimeException("the value of layout_xxxPercent invalid! ==>" + percentStr); } String floatVal; String lastAlpha; float percent; int len = percentStr.length(); if (matcher.matches()) { //extract the float value floatVal = matcher.group(1); lastAlpha = percentStr.substring(len - 1); percent = Float.parseFloat(floatVal) / 100f; } else { //extract the float value floatVal = percentStr.substring(0, percentStr.indexOf("px")); lastAlpha = percentStr.substring(len - 1); percent = Float.parseFloat(floatVal); } PercentLayoutInfo.PercentVal percentVal = new PercentLayoutInfo.PercentVal(); percentVal.percent = percent; if (percentStr.endsWith(PercentLayoutInfo.BASEMODE.SW)) { percentVal.basemode = PercentLayoutInfo.BASEMODE.BASE_SCREEN_WIDTH; } else if (percentStr.endsWith(PercentLayoutInfo.BASEMODE.SH)) { percentVal.basemode = PercentLayoutInfo.BASEMODE.BASE_SCREEN_HEIGHT; } else if (percentStr.endsWith(PercentLayoutInfo.BASEMODE.PERCENT)) { if (isOnWidth) { percentVal.basemode = PercentLayoutInfo.BASEMODE.BASE_WIDTH; } else { percentVal.basemode = PercentLayoutInfo.BASEMODE.BASE_HEIGHT; } } else if (percentStr.endsWith(PercentLayoutInfo.BASEMODE.W)) { percentVal.basemode = PercentLayoutInfo.BASEMODE.BASE_WIDTH; } else if (percentStr.endsWith(PercentLayoutInfo.BASEMODE.H)) { percentVal.basemode = PercentLayoutInfo.BASEMODE.BASE_HEIGHT; } else if (percentStr.endsWith(PercentLayoutInfo.BASEMODE.PX)) { percentVal.basemode = PercentLayoutInfo.BASEMODE.ABSOLUTE_PX; } else { throw new IllegalArgumentException("the " + percentStr + " must be endWith [%|w|h|sw|sh]"); } return percentVal; }

好啦，终于看到核心代码了，不做太多解释，相信都看得懂，简单来说就是获取到我们设置的值，然后判断我们设置的值属于哪种类型：

类型有：

private enum BASEMODE { BASE_WIDTH, BASE_HEIGHT, BASE_SCREEN_WIDTH, BASE_SCREEN_HEIGHT, ABSOLUTE_PX; /** * width_parent */ public static final String PERCENT = "%"; /** * width_parent */ public static final String W = "w"; /** * height_parent */ public static final String H = "h"; /** * width_screen */ public static final String SW = "sw"; /** * height_screen */ public static final String SH = "sh"; /** * absolute px */ public static final String PX = "px"; }

就是我们布局中写的：

app:layout_widthPercent="10%w" app:layout_heightPercent="10%h" app:layout_widthPercent="20%sw" app:layout_heightPercent="20%sh" app:layout_widthPercent="200px" app:layout_heightPercent="200px"

小伙伴是不是看懂了呢？比如20％sw，就是把20跟sw取出来，然后封装进类中。

好啦，我们已经拿到我们在布局中设置的属性了，然后我们就得根据我们设置的值重新赋给子控件了。

在onMeasure中我们找到adjustChildren方法：

/** * Iterates over children and changes their width and height to one calculated from percentage * values. * * @param widthMeasureSpec Width MeasureSpec of the parent ViewGroup. * @param heightMeasureSpec Height MeasureSpec of the parent ViewGroup. */ public void adjustChildren(int widthMeasureSpec, int heightMeasureSpec) { if (Log.isLoggable(TAG, Log.DEBUG)) { Log.d(TAG, "adjustChildren: " + mHost + " widthMeasureSpec: " + View.MeasureSpec.toString(widthMeasureSpec) + " heightMeasureSpec: " + View.MeasureSpec.toString(heightMeasureSpec)); } int widthHint = View.MeasureSpec.getSize(widthMeasureSpec); int heightHint = View.MeasureSpec.getSize(heightMeasureSpec); if (Log.isLoggable(TAG, Log.DEBUG)) Log.d(TAG, "widthHint = " + widthHint + " , heightHint = " + heightHint); for (int i = 0, N = mHost.getChildCount(); i < N; i++) { View view = mHost.getChildAt(i); ViewGroup.LayoutParams params = view.getLayoutParams(); if (Log.isLoggable(TAG, Log.DEBUG)) { Log.d(TAG, "should adjust " + view + " " + params); } if (params instanceof PercentLayoutParams) { PercentLayoutInfo info = ((PercentLayoutParams) params).getPercentLayoutInfo(); if (Log.isLoggable(TAG, Log.DEBUG)) { Log.d(TAG, "using " + info); } if (info != null) { supportTextSize(widthHint, heightHint, view, info); supportPadding(widthHint, heightHint, view, info); supportMinOrMaxDimesion(widthHint, heightHint, view, info); if (params instanceof ViewGroup.MarginLayoutParams) { info.fillMarginLayoutParams((ViewGroup.MarginLayoutParams) params, widthHint, heightHint); } else { info.fillLayoutParams(params, widthHint, heightHint); } } } } }

遍历我们的子控件，然后根据我们上面获取到的info类，进行重新布局：

if (info != null) { supportTextSize(widthHint, heightHint, view, info); supportPadding(widthHint, heightHint, view, info); supportMinOrMaxDimesion(widthHint, heightHint, view, info); if (params instanceof ViewGroup.MarginLayoutParams) { info.fillMarginLayoutParams((ViewGroup.MarginLayoutParams) params, widthHint, heightHint); } else { info.fillLayoutParams(params, widthHint, heightHint); } }

demo中我们看到了：

我们有设置一个app:layout_textSizePercent：

看到这我们找到一个方法，没错！也就是这里对textview设置的size大小的：

supportTextSize(widthHint, heightHint, view, info);

我们往下走：

private void supportTextSize(int widthHint, int heightHint, View view, PercentLayoutInfo info) { //textsize percent support PercentLayoutInfo.PercentVal textSizePercent = info.textSizePercent; if (textSizePercent == null) return; float textSize; int base = getBaseByModeAndVal(widthHint, heightHint, textSizePercent.basemode); if (textSizePercent.basemode == PercentLayoutInfo.BASEMODE.ABSOLUTE_PX) { textSize = ViewUtils.scaleTextValue(mHost.getContext(), textSizePercent.percent); } else { textSize = (int) (base * textSizePercent.percent); } //Button 和 EditText 是TextView的子类 if (view instanceof TextView) { ((TextView) view).setTextSize(TypedValue.COMPLEX_UNIT_PX, textSize); } }

这里如果我们是直接设置的px的话（如：app:layout_textSizePercent=”28px”），我们就需要根据ui基准，然后算出在我们手机上应该显示多少：

int base = getBaseByModeAndVal(widthHint, heightHint, textSizePercent.basemode); if (textSizePercent.basemode == PercentLayoutInfo.BASEMODE.ABSOLUTE_PX) { textSize = ViewUtils.scaleTextValue(mHost.getContext(), textSizePercent.percent); } else { textSize = (int) (base * textSizePercent.percent); }

如果是直接设置的20％w，20％h，20％sh这样的值的话，我们就需要用父布局的宽、高、屏幕宽、高乘一个我们设置进去的百分比进行计算了：

textSize = (int) (base * textSizePercent.percent);

好啦！！！剩下的几个方法也都差不多，我就不一一讲了哈：

嗯嗯～！我们的百分比跟px布局差不多就讲完啦～，下面看看咋使用它哈：

如果要直接使用px布局的话（不用px布局可不需要做第一步与第二步）： 1、在项目的manifest文件中定义好ui设计的基准（如iphone6）：

<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.example.leo.textdemo" > <application android:name=".BaseApplication" android:allowBackup="true" android:icon="@mipmap/ic_launcher" android:label="@string/app_name" android:supportsRtl="true" android:theme="@style/APPTheme" > <meta-data android:name="UI_WIDTH" android:value="750"/> <meta-data android:name="UI_HEIGHT" android:value="1334"/> <meta-data android:name="UI_DENSITY" android:value="2"/> <activity android:name=".MainActivity" > <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> <activity android:name=".SimpleMenuActivtiy"> </activity> </application></manifest>

2、在app中的application文件中，初始化布局：

package com.example.leo.textdemo;import android.app.Application;import android.content.Context;import com.yasin.px_percent_layout.utils.PxAppConfig;/** * Created by leo on 17/2/9. */public class BaseApplication extends Application { @Override protected void attachBaseContext(Context base) { super.attachBaseContext(base); PxAppConfig.init(base); }}

然后我们就可以在布局文件中用起来了：

好啦！！！文章有点长哈，最后附上项目的git链接： https://github.com/913453448/PercentLayoutDemo

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