王学岗高级UI8——————屏幕适配

一

1,屏幕分辨率限定符，已经过时了，不在介绍
2,smallestWidth 限定符
使用：(1)android studio中安装ScreenMatch插件;
(2)点击values文件夹下的任意文件，右击，选中ScreenMatch。

生成如下文件

然后移动screenMatch_example_dimens文件到values文件夹下。并修改名字为dimens
右击dimens文件，然后会生成如下

二动态运行时的屏幕适配

package com.dn_alan.myapplication.pixel;

import android.content.Context;
import android.util.DisplayMetrics;
import android.view.WindowManager;

public class Utils {
    private static Utils utils;
    private Context mContext;
    //这里是设计稿参考宽高,UI设计师按照这个宽高设计
    private static final float STANDARD_WIDTH = 1080;
    private static final float STANDARD_HEIGHT = 1920;
    //这里是屏幕显示宽高，当前屏幕的宽和高
    private int mDisplayWidth;
    private int mDisplayHeight;

    public Utils(Context context) {
        mContext = context;
        //获取屏幕宽高
        if (mDisplayWidth == 0 || mDisplayHeight == 0) {
            WindowManager windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
            if (windowManager != null) {
                //宽高获取
                DisplayMetrics displayMetrics = new DisplayMetrics();
                //如果不是NavigationBar沉浸式（不包含NavigationBar）
                windowManager.getDefaultDisplay().getMetrics(displayMetrics);
//                windowManager.getDefaultDisplay().getRealMetrics(displayMetrics);//真实屏幕宽高
                //判断当前的横竖屏
                if (displayMetrics.widthPixels > displayMetrics.heightPixels) {
                    //横屏
                    mDisplayWidth = displayMetrics.heightPixels;
                    mDisplayHeight = displayMetrics.widthPixels - getStatusBarHeight(context);
                } else {
                    //竖屏
                    mDisplayWidth = displayMetrics.widthPixels;
                    mDisplayHeight = displayMetrics.heightPixels - getStatusBarHeight(context);
                }
            }
        }
    }

    public static Utils getInstance(Context context) {
        if (utils == null) {
            utils = new Utils(context);
        }
        return utils;
    }

    //获取状态栏高度
    public int getStatusBarHeight(Context context) {
        int resId = context.getResources().getIdentifier("status_bar_height", "dimen", "android");
        //大于0表示resID存在
        if (resId > 0) {
            return context.getResources().getDimensionPixelSize(resId);//获取具体的像素值
        }
        return 0;
    }

    //获取水平方向的缩放比例
    public float getHorizontalScale() {
        return mDisplayWidth / STANDARD_WIDTH;
    }

    //获取垂直方向的缩放比例
    public float getVerticalScale() {
        return mDisplayHeight / (STANDARD_HEIGHT - getStatusBarHeight(mContext));
    }
}

我们重写RelativeLayout布局，重写它的onMeasure();

package com.dn_alan.myapplication.pixel;

import android.content.Context;
import android.util.AttributeSet;
import android.view.View;
import android.widget.RelativeLayout;

public class ScreenAdapterLayout extends RelativeLayout {
    private boolean flag;

    public ScreenAdapterLayout(Context context) {
        super(context);
    }

    public ScreenAdapterLayout(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public ScreenAdapterLayout(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        if (!flag) { //防止两次测量，onMessasure()执行了两次
            flag = true;
            //获取横竖方向等比
            float scaleX = Utils.getInstance(getContext()).getHorizontalScale();
            float scaleY = Utils.getInstance(getContext()).getVerticalScale();
            //子View个数
            int childCount = getChildCount();
            //遍历所有的子View，改变所有的子View的宽和高
            for (int i = 0; i < childCount; i++) {
                View child = getChildAt(i);
                LayoutParams params = (LayoutParams) child.getLayoutParams();
                //当前子View的宽
                params.width = (int) (params.width * scaleX);
                params.height = (int) (params.height * scaleY);
                params.leftMargin = (int) (params.leftMargin * scaleX);
                params.rightMargin = (int) (params.rightMargin * scaleX);
                params.topMargin = (int) (params.topMargin * scaleY);
                params.bottomMargin = (int) (params.bottomMargin * scaleY);
                child.setPadding((int) (child.getPaddingLeft() * scaleX), (int) (child.getPaddingTop() * scaleY),
                        (int) (child.getPaddingRight() * scaleX), (int) (child.getPaddingBottom() * scaleY));
            }
        }
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    }
}

在布局中可以直接使用px为单位

三密度适配(网上比较火的今日头条适配就是密度适配)

package com.dn_alan.myapplication.density;

import android.app.Activity;
import android.app.Application;
import android.content.ComponentCallbacks;
import android.content.res.Configuration;
import android.util.DisplayMetrics;

/**
 * 修改density，densityDpi值-直接更改系统内部对于目标尺寸而言的像素密度
 */
public class DensityUtils {
    private static final float WIDTH = 360;//参考像素密度(dp)
    private static float appDensity;//表示屏幕密度
    private static float appScaleDensity;//字体缩放比例，默认为appDensity

    public static void setDensity(final Application application, Activity activity) {
        //获取当前屏幕信息
        DisplayMetrics displayMetrics = application.getResources().getDisplayMetrics();
        if (appDensity == 0) {
            //初始化赋值
            appDensity = displayMetrics.density;
            appScaleDensity = displayMetrics.scaledDensity;
            //监听字体变化
            application.registerComponentCallbacks(new ComponentCallbacks() {
                @Override
                public void onConfigurationChanged(Configuration newConfig) {
                    //字体发生更改，重新计算scaleDensity
                    if (newConfig != null && newConfig.fontScale > 0) {
                        appScaleDensity = application.getResources().getDisplayMetrics().scaledDensity;
                    }
                }

                @Override
                public void onLowMemory() {

                }
            });
        }
        //计算目标density scaledDensity
        //屏幕宽度：displayMetrics.widthPixels
        float targetDensity = displayMetrics.widthPixels / WIDTH;//1080/360=3;
        float targetScaleDensity = targetDensity * (appScaleDensity / appDensity);
        int targetDensityDpi = (int) (targetDensity * 160);
        //替换Activity的值
        //px = dp * (dpi / 160)
        DisplayMetrics dm = activity.getResources().getDisplayMetrics();
        dm.density = targetDensity;  //(dpi/160) 后得到的值
        dm.scaledDensity = targetScaleDensity;
        dm.densityDpi = targetDensityDpi;  //dpi
    }
}

package com.dn_alan.myapplication.density;

import android.content.Intent;
import android.os.Bundle;
import android.view.View;

import com.dn_alan.myapplication.R;

public class DensityActivity extends BaseActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
//        //设置density
        DensityUtils.setDensity(getApplication(), this);
        setContentView(R.layout.activity_density);
    }

}