如何实现Android 布局背景模糊化处理

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 http://www.cnblogs.com/lipeil/p/3997992.html

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;
}