Activity 类似Dialog主题背景高斯模糊

 可以参考此文章：Android中Activity和AppcompatActivity的区别(详细解析)_today_work的博客-CSDN博客

/**
 * 今天接到的需求是Activty 主题是Dialog样式,背景需要是桌面当时截图并做高斯模糊
 * 1、Android Studio 默认继承AppcompactActivity，这时需要改成继承Activity  主题使用@android:style/Theme.Translucent.NoTitleBar.Fullscreen
 * 2、AppcompaActivity 主界面带有toolbar的标题栏，而Activity 则没有；
 * 3、AppcompaActivity theme主题只能用android:theme=”@style/AppTheme （appTheme主题或者其子类），
 * 而不能用android:style。否则会提示错误： Caused by: java.lang.IllegalStateException: You need to use a Theme.AppCompat theme (or descendant) with this activity.
 */

<application
        android:name=".App"
        android:allowBackup="true"
        android:icon="@mipmap/icon_app_pip_210x"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/icon_app_pip_210x"
        android:supportsRtl="true"
        android:theme="@android:style/Theme.Translucent.NoTitleBar.Fullscreen">
        <activity
            android:name=".MainActivity"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

这里是同事给出的方法
/**
     * 反射截图
     * @param isLandscape 横竖屏方式截屏会有差异
     * @param context 上下文
     * @return bitmap
     */
    public static Bitmap screenshotSystem(boolean isLandscape,Context context) {
        Class<?> demo;
        Bitmap bitmap = null;
        try {
            demo = Class.forName("android.view.SurfaceControl");
            Method method = demo.getMethod("screenshot", Rect.class, int.class, int.class, int.class);
            Object obj = method.invoke(null, new Rect(), Util.getScreenWidth(context), Util.getScreenHeight(context), isLandscape ? 0 : 1);
            //最后一个参数是拍摄角度0,1,2,3对应0,90,180,270
            bitmap = (Bitmap) obj;
        } catch (Exception e) {
            e.printStackTrace();
            Log.d("yyy", "screenshotSystem: error");
        }
        return bitmap;
    }

    /**
     * bitmap整体先缩小
     * @param bitmap
     * @return
     */
    public static Bitmap small(Bitmap bitmap) {
        if (bitmap == null) {
            return null;
        }
        int w = bitmap.getWidth();
        int h = bitmap.getHeight();
        int retX, retY;
        Bitmap bmp = null;
        retX = 0;
        retY = 0;
        Matrix matrix = new Matrix();
        matrix.postScale(1 / 4f, 1 / 4f);
        bmp = Bitmap.createBitmap(bitmap, retX, retY, w, h, matrix,
                true);
        if (!bitmap.equals(bmp) && !bitmap.isRecycled()) {
            bitmap.recycle();   //标记为被回收状态（dead），不可再使用
            bitmap = null;
        }

        return bmp;// Bitmap.createBitmap(bitmap, retX, retY, nw, nh, null,
    }

    /**
     * 这里不是很懂  //android api 30把 hardware bitmap 转换成software bitmap
     * @param src
     * @return
     */
    @RequiresApi(api = Build.VERSION_CODES.P)
    public static Bitmap convertHardWareBitmap(Bitmap src) {
        if (src.getConfig() != Bitmap.Config.HARDWARE) {
            //return Bitmap.createBitmap(src, 0, 0, src.getWidth(), src.getHeight());
            return src;
        }

        final int w = src.getWidth();
        final int h = src.getHeight();
        // For hardware bitmaps, use the Picture API to directly create a software bitmap
        Picture picture = new Picture();
        Canvas canvas = picture.beginRecording(w, h);
        canvas.drawBitmap(src, 0, 0, null);
        picture.endRecording();
        return Bitmap.createBitmap(picture, w, h,
                Bitmap.Config.ARGB_8888);
    }
    
    /**
     * 对缩小的bitmap 进行高斯模糊，效率高
     * @param bkg
     * @param context
     * @return
     */
    public static Bitmap blur(Bitmap bkg,Context context) {
        final RenderScript rs = RenderScript.create(context);
        final Allocation input = Allocation.createFromBitmap(rs, bkg, Allocation.MipmapControl.MIPMAP_NONE,
                Allocation.USAGE_SCRIPT);
        final Allocation output = Allocation.createTyped(rs, input.getType());
        final ScriptIntrinsicBlur script = ScriptIntrinsicBlur.create(rs, Element.U8_4(rs));
        script.setRadius(5);
        script.setInput(input);
        script.forEach(output);
        output.copyTo(bkg);
        return bkg;
    }


    /**
     * 接收缩小高斯模糊后的bitmap 恢复原来截图的大小
     * @param bitmap
     * @return
     */
    public static Bitmap big(Bitmap bitmap) {
        Matrix matrix = new Matrix();
        matrix.postScale(4f, 4f); //长和宽放大缩小的比例
        Bitmap resizeBmp = Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth(), bitmap.getHeight(), matrix, true);
        return resizeBmp;
    }

MainActivity 继承Activity  在onCreate  方法截图 给Decorview 设置背景
public class MainActivity extends Activity implements View.OnClickListener {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        backgroundBokeh();
        super.onCreate(savedInstanceState);
        setContentView(R.layout.source_view);
        initView();
    }

    /**
     * 背景虚化
     */
    @RequiresApi(api = Build.VERSION_CODES.P)
    public void backgroundBokeh() {
        Bitmap blur = Util.screenshotSystem(getResources().getConfiguration().orientation== Configuration.ORIENTATION_LANDSCAPE,this);
        blur = Util.small(blur);
        blur = Util.convertHardWareBitmap(blur);
        blur = Util.blur(blur,this);
        blur = Util.big(blur);
        getWindow().getDecorView().setBackground(new BitmapDrawable(this.getResources(),
                blur));
    }
}