Android中实现布局背景模糊化处理的方法

在模仿 IOS 密码输入页面的时候发现其背景有模糊处理,于是了解了一下并记录下来,以便使用.在Android 中具体实现方法如下
查考 //www.jb51.net/article/64781.htm

private void applyBlur() {        // 获取壁纸管理器    WallpaperManager wallpaperManager = WallpaperManager.getInstance(this.getContext());    // 获取当前壁纸    Drawable wallpaperDrawable = wallpaperManager.getDrawable();    // 将Drawable,转成Bitmap    Bitmap bmp = ((BitmapDrawable) wallpaperDrawable).getBitmap();       blur(bmp);  }

下面之所以要进行small 和big的处理,是因为仅仅靠ScriptIntrinsicBlur 来处理模式,不能到达更模式的效果,如果需要加深模式效果就需要先把背景图片缩小,在处理完之后再放大.这个可以使用Matrix 来实现,而且这样可以缩短模糊化得时间

@TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR1)  private void blur(Bitmap bkg) {    long startMs = System.currentTimeMillis();    float radius = 20;     bkg = small(bkg);   Bitmap bitmap = bkg.copy(bkg.getConfig(), true);    final RenderScript rs = RenderScript.create(this.getContext());   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(radius);   script.setInput(input);   script.forEach(output);   output.copyTo(bitmap);    bitmap = big(bitmap);   setBackground(new BitmapDrawable(getResources(), bitmap));    rs.destroy();    Log.d("zhangle","blur take away:" + (System.currentTimeMillis() - startMs )+ "ms");  }   private 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;  }   private static Bitmap small(Bitmap bitmap) {    Matrix matrix = new Matrix();     matrix.postScale(0.25f,0.25f); //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; }

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