An {@link Animation} used to enlarge the popup into view.

class ResizeAnimation extends Animation {
 /**
  * The {@link PopupPanel} being affected.
  */
 PopupPanel curPanel = null;

 /**
  * Indicates whether or not the {@link PopupPanel} is in the process of
  * unloading. If the popup is unloading, then the animation just does
  * cleanup.
  */
 bool isUnloading = false;

 /**
  * The offset height and width of the current {@link PopupPanel}.
  */
 int offsetHeight, offsetWidth = -1;

 /**
  * A bool indicating whether we are showing or hiding the popup.
  */
 bool showing = false;

 /**
  * The timer used to delay the show animation.
  */
 Timer showTimer;

 /**
  * A bool indicating whether the glass element is currently attached.
  */
 bool glassShowing = false;

 //HandlerRegistration resizeRegistration;

 /**
  * Create a new {@link ResizeAnimation}.
 *
  * @param panel the panel to affect
  */
 ResizeAnimation(PopupPanel panel) {
   this.curPanel = panel;
 }

 /**
  * Open or close the content. This method always called immediately after
  * the PopupPanel showing state has changed, so we base the animation on the
  * current state.
 *
  * @param showing true if the popup is showing, false if not
  */
 void setState(bool showing, bool isUnloading) {
   // Immediately complete previous open/close animation
   this.isUnloading = isUnloading;
   cancel();

   // If there is a pending timer to start a show animation, then just cancel
   // the timer and complete the show operation.
   if (showTimer != null) {
     showTimer.cancel();
     showTimer = null;
     onComplete();
   }

   // Update the logical state.
   curPanel.showing = showing;
   curPanel.updateHandlers();

   // Determine if we need to animate
   bool animate = !isUnloading && curPanel._isAnimationEnabled;
   if (curPanel.animType != AnimationType.CENTER && !showing) {
     animate = false;
   }

   // Open the new item
   this.showing = showing;
   if (animate) {
     // impl.onShow takes some time to complete, so we do it before starting
     // the animation. If we move this to onStart, the animation will look
     // choppy or not run at all.
     if (showing) {
       maybeShowGlass();

       // Set the position attribute, and then attach to the Dom. Otherwise,
       // the PopupPanel will appear to 'jump' from its static/relative
       // position to its absolute position (issue #1231).
       Dom.setStyleAttribute(curPanel.getElement(), "position", "absolute");
       if (curPanel.topPosition != -1) {
         curPanel.setPopupPosition(curPanel.leftPosition,
             curPanel.topPosition);
       }
       PopupPanel.impl.setClip(curPanel.getElement(), getRectString(0, 0, 0, 0));
       RootPanel.get().add(curPanel);
       PopupPanel.impl.onShow(curPanel.getElement());

       // Wait for the popup panel and iframe to be attached before running
       // the animation. We use a Timer instead of a DeferredCommand so we
       // can cancel it if the popup is hidden synchronously.
       showTimer = new Timer.get(() {
         showTimer = null;
         run(PopupPanel.ANIMATION_DURATION);
       });
       showTimer.schedule(1);
     } else {
       run(PopupPanel.ANIMATION_DURATION);
     }
   } else {
     onInstantaneousRun();
   }
 }


 void onComplete() {
   if (!showing) {
     maybeShowGlass();
     if (!isUnloading) {
       RootPanel.get().remove(curPanel);
     }
     PopupPanel.impl.onHide(curPanel.getElement());
   }
   PopupPanel.impl.setClip(curPanel.getElement(), "rect(auto, auto, auto, auto)");
   Dom.setStyleAttribute(curPanel.getElement(), "overflow", "visible");
 }


 void onStart() {
   offsetHeight = curPanel.getOffsetHeight();
   offsetWidth = curPanel.getOffsetWidth();
   Dom.setStyleAttribute(curPanel.getElement(), "overflow", "hidden");
   super.onStart();
 }


 void onUpdate(double progress) {
   if (!showing) {
     progress = 1.0 - progress;
   }

   // Determine the clipping size
   int top = 0;
   int left = 0;
   int right = 0;
   int bottom = 0;
   int height = (progress * offsetHeight).toInt();
   int width = (progress * offsetWidth).toInt();
   switch (curPanel.animType) {
     case AnimationType.ROLL_DOWN:
       right = offsetWidth;
       bottom = height;
       break;
     case AnimationType.CENTER:
       top = (offsetHeight - height) >> 1;
       left = (offsetWidth - width) >> 1;
       right = left + width;
       bottom = top + height;
       break;
     case AnimationType.ONE_WAY_CORNER:
       if (LocaleInfo.getCurrentLocale().isRTL()) {
         left = offsetWidth - width;
       }
       right = left + width;
       bottom = top + height;
       break;
   }
   // Set the rect clipping
   PopupPanel.impl.setClip(curPanel.getElement(), getRectString(top, right, bottom, left));
 }

 /**
  * Returns a rect string.
  */
 String getRectString(int top, int right, int bottom, int left) {
   return "rect(${top}px, ${right}px, ${bottom}px, ${left}px)";
 }

 /**
  * Show or hide the glass.
  */
 void maybeShowGlass() {
   if (showing) {
     if (curPanel._isGlassEnabled) {
       dart_html.document.body.append(curPanel.glass);
       PopupPanel.impl.onShow(curPanel.glass);

//        resizeRegistration = dart_html.document.window.addResizeHandler(curPanel.glassResizer);
       curPanel.glassResizer.onResize(null);

       glassShowing = true;
     }
   } else if (glassShowing) {
     //dart_html.document.body.removeChild(curPanel.glass);
     curPanel.glass.remove();
     PopupPanel.impl.onHide(curPanel.glass);

//      resizeRegistration.removeHandler();
//      resizeRegistration = null;

     glassShowing = false;
   }
 }

 void onInstantaneousRun() {
   maybeShowGlass();
   if (showing) {
     // Set the position attribute, and then attach to the Dom. Otherwise,
     // the PopupPanel will appear to 'jump' from its static/relative
     // position to its absolute position (issue #1231).
     Dom.setStyleAttribute(curPanel.getElement(), "position", "absolute");
     if (curPanel.topPosition != -1) {
       curPanel.setPopupPosition(curPanel.leftPosition, curPanel.topPosition);
     }
     RootPanel.get().add(curPanel);
     PopupPanel.impl.onShow(curPanel.getElement());
   } else {
     if (!isUnloading) {
       RootPanel.get().remove(curPanel);
     }
     PopupPanel.impl.onHide(curPanel.getElement());
   }
   Dom.setStyleAttribute(curPanel.getElement(), "overflow", "visible");
 }
}