小编jor*_*nti的帖子

我目前正在使用包含ImageViews的GridView,并希望我的图像背后有阴影.例如,在网格中可能有15个图像随时可见.在假设我希望我的屏幕以50fps渲染以显得平滑的情况下工作,我的数学表明我希望每个ImageView的总绘制时间不会差于大约1.3ms.

我看了一下Romain Guy如何在他的Shelves应用程序中做阴影:http: //code.google.com/p/shelves/source/browse/trunk/Shelves/src/org/curiouscreature/android/shelves/util/ ImageUtilities.java

这似乎有道理,所以我创建了以下类:

 public class ShadowImageView extends ImageView {
     private static final int SHADOW_RADIUS = 8;
     private static final int SHADOW_COLOR = 0x99000000;
     private static final Paint SHADOW_PAINT = new Paint();

     static {
         SHADOW_PAINT.setShadowLayer(SHADOW_RADIUS / 2.0f, 0.0f, 
             0.0f, SHADOW_COLOR);
         SHADOW_PAINT.setColor(0xFF000000);
         SHADOW_PAINT.setStyle(Paint.Style.FILL);
     }

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

     @Override
     public void onDraw(Canvas canvas) {
         final int containerWidth = getMeasuredWidth();
         final int containerHeight = getMeasuredHeight();

         canvas.drawRect(
                 SHADOW_RADIUS / 2.0f,
                 SHADOW_RADIUS / 2.0f,
                 containerWidth …