Improving widget transitions:

-> When a widget has no configuration activity, we bind
   and inflate it when the user picks it up. This allows
   us to smoothly transition between it's preview and
   some actual state of the widget when it is dropped.
-> When a widget has a configuration activity, we delay
   the above process until the configuration activity
   has been run at which time we transition between
   the preview and the actual widget.

Change-Id: I5265cd98400d70e5e75c3dcd21e322ed0b352d7b

src/com/android/launcher2/DragView.java

@@ -33,6 +33,7 @@ import com.android.launcher.R;
 
 public class DragView extends View {
     private Bitmap mBitmap;
+    private Bitmap mCrossFadeBitmap;
     private Paint mPaint;
     private int mRegistrationX;
     private int mRegistrationY;
@@ -41,6 +42,7 @@ public class DragView extends View {
     private Rect mDragRegion = null;
     private DragLayer mDragLayer = null;
     private boolean mHasDrawn = false;
+    private float mCrossFadeProgress = 0f;
 
     ValueAnimator mAnim;
     private float mOffsetX = 0.0f;
@@ -164,9 +166,43 @@ public class DragView extends View {
             p.setColor(0xaaffffff);
             canvas.drawRect(0, 0, getWidth(), getHeight(), p);
         }
+        if (mPaint == null) {
+            mPaint = new Paint();
+        }
 
         mHasDrawn = true;
+        boolean crossFade = mCrossFadeProgress > 0 && mCrossFadeBitmap != null;
+        if (crossFade) {
+            int alpha = crossFade ? (int) (255 * (1 - mCrossFadeProgress)) : 255;
+            mPaint.setAlpha(alpha);
+        }
         canvas.drawBitmap(mBitmap, 0.0f, 0.0f, mPaint);
+        if (crossFade) {
+            mPaint.setAlpha((int) (255 * mCrossFadeProgress));
+            canvas.save();
+            float sX = (mBitmap.getWidth() * 1.0f) / mCrossFadeBitmap.getWidth();
+            float sY = (mBitmap.getHeight() * 1.0f) / mCrossFadeBitmap.getHeight();
+            canvas.scale(sX, sY);
+            canvas.drawBitmap(mCrossFadeBitmap, 0.0f, 0.0f, mPaint);
+            canvas.restore();
+        }
+    }
+
+    public void setCrossFadeBitmap(Bitmap crossFadeBitmap) {
+        mCrossFadeBitmap = crossFadeBitmap;
+    }
+
+    public void crossFade(int duration) {
+        ValueAnimator va = ValueAnimator.ofFloat(0f, 1f);
+        va.setDuration(duration);
+        va.setInterpolator(new DecelerateInterpolator(1.5f));
+        va.addUpdateListener(new AnimatorUpdateListener() {
+            @Override
+            public void onAnimationUpdate(ValueAnimator animation) {
+                mCrossFadeProgress = animation.getAnimatedFraction();
+            }
+        });
+        va.start();
     }
 
     public void setPaint(Paint paint) {