图片阴影

public void drawImageDropShadow(){BlurMaskFilter blurFilter = new BlurMaskFilter(3, BlurMaskFilter.Blur.OUTER);Paint shadowPaint = new Paint();shadowPaint.setMaskFilter(blurFilter);int[] offsetXY =new int[2];Bitmap originalBitmap = BitmapFactory.decodeResource(this.getResources(),R.drawable.favoritelist);Bitmap shadowBitmap = originalBitmap.extractAlpha(shadowPaint,offsetXY);Bitmap shadowImage32 = shadowBitmap.copy(Bitmap.Config.ARGB_8888, true);Canvas c = new Canvas(shadowImage32);c.drawBitmap(originalBitmap, 0,0, null);ImageView imageView1 = (ImageView)findViewById(R.id.shadowImageView);imageView1.setImageBitmap(shadowImage32);}?

下面是设置LinearLayout的背景。用xml文件画Rectangle来作为LinearLayout的背景。思想和前面的一样。不同的是通过.xml创建一个Drawable，然后

制定 宽和高， 将Drawable转化bitmap 画阴影bitmap，然后将阴影bitmap转化为drawable，最后将drawable设置为LinearLayout的背景。

代码如下：

说明需要一个方法：将drawable转化为bitmap

一般通用的方法为:

public static Bitmap drawableToBitmap(Drawable drawable) {Bitmap bitmap = Bitmap.createBitmap(drawable.getIntrinsicWidth(),drawable.getIntrinsicHeight(),drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888: Bitmap.Config.RGB_565);Canvas canvas = new Canvas(bitmap);//canvas.setBitmap(bitmap);drawable.setBounds(0, 0, drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight());drawable.draw(canvas);return bitmap;}
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我创建的drawable是一个xml文件，而不是图片，所以，drawable.getIntrinsicHeight()得不到值。所以要手动传递参数设宽度和高度。代码如下：
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private Bitmap drawableToBitmap(Drawable drawable,int width,int height) {Bitmap bitmap = Bitmap.createBitmap(width,height,drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888: Bitmap.Config.RGB_565);Canvas canvas = new Canvas(bitmap);drawable.setBounds(0, 0, width, height);drawable.draw(canvas);return bitmap;}
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最后设置阴影的代码：

public void drawLayoutDropShadow(){LinearLayout linearLayout = (LinearLayout)findViewById(R.id.testShadowLinearLayout);BlurMaskFilter blurFilter = new BlurMaskFilter(3, BlurMaskFilter.Blur.OUTER);Paint shadowPaint = new Paint();shadowPaint.setMaskFilter(blurFilter);Drawable drawable = this.getResources().getDrawable(R.drawable.backgroundservicescolor);int[] offsetXY =new int[2];Bitmap originalBitmap = drawableToBitmap(drawable,200,100);Bitmap shadowBitmap = originalBitmap.extractAlpha(shadowPaint,offsetXY);Bitmap shadowImage32 = shadowBitmap.copy(Bitmap.Config.ARGB_8888, true);Canvas c = new Canvas(shadowImage32);c.drawBitmap(originalBitmap, 0,0, null);Drawable d =new BitmapDrawable(shadowImage32);linearLayout.setBackgroundDrawable(d);} 
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最后的效果如下：

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