DevTools: always do partial viewport update in console

third_party/WebKit/Source/devtools/front_end/console/ConsoleViewport.js

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 303 matching lines @@
       this._firstActiveIndex = -1;
       this._lastActiveIndex = -1;
       return;
     }
 
     var selection = this.element.getComponentSelection();
     var shouldRestoreSelection = this._updateSelectionModel(selection);
 
     var visibleFrom = this.element.scrollTop;
     var visibleHeight = this._visibleHeight();
-    var isInvalidating = !this._cumulativeHeights;
 
     for (var i = 0; i < this._renderedItems.length; ++i) {
       // Tolerate 1-pixel error due to double-to-integer rounding errors.
       if (this._cumulativeHeights &&
           Math.abs(this._cachedItemHeight(this._firstActiveIndex + i) - this._renderedItems[i].element().offsetHeight) >
               1)
         delete this._cumulativeHeights;
     }
     this._rebuildCumulativeHeightsIfNeeded();
-    var oldFirstActiveIndex = this._firstActiveIndex;
-    var oldLastActiveIndex = this._lastActiveIndex;
     var activeHeight = visibleHeight * 2;
     // When the viewport is scrolled to the bottom, using the cumulative heights estimate is not
     // precise enough to determine next visible indices. This stickToBottom check avoids extra
     // calls to refresh in those cases.
     if (this._stickToBottom) {
       this._firstActiveIndex =
           Math.max(this._itemCount - Math.ceil(activeHeight / this._provider.minimumRowHeight()), 0);
       this._lastActiveIndex = this._itemCount - 1;
     } else {
       this._firstActiveIndex = Math.max(
@@ skipping 13 matching lines @@
      * @this {Console.ConsoleViewport}
      */
     function prepare() {
       this._topGapElement.style.height = topGapHeight + 'px';
       this._bottomGapElement.style.height = bottomGapHeight + 'px';
       this._topGapElement._active = !!topGapHeight;
       this._bottomGapElement._active = !!bottomGapHeight;
       this._contentElement.style.setProperty('height', '10000000px');
     }
 
-    if (isInvalidating)
-      this._fullViewportUpdate(prepare.bind(this));
-    else
-      this._partialViewportUpdate(oldFirstActiveIndex, oldLastActiveIndex, prepare.bind(this));
+    this._partialViewportUpdate(prepare.bind(this));
     this._contentElement.style.removeProperty('height');
     // Should be the last call in the method as it might force layout.
     if (shouldRestoreSelection)
       this._restoreSelection(selection);
     if (this._stickToBottom)
       this.element.scrollTop = 10000000;
   }
 
   /**
    * @param {function()} prepare
    */
-  _fullViewportUpdate(prepare) {
-    for (var i = 0; i < this._renderedItems.length; ++i)
-      this._renderedItems[i].willHide();
-    prepare();
-    this._renderedItems = [];
-    this._contentElement.removeChildren();
-    for (var i = this._firstActiveIndex; i <= this._lastActiveIndex; ++i) {
-      var viewportElement = this._providerElement(i);
-      this._contentElement.appendChild(viewportElement.element());
-      this._renderedItems.push(viewportElement);
-    }
-    for (var i = 0; i < this._renderedItems.length; ++i)
-      this._renderedItems[i].wasShown();
-  }
-
-  /**
-   * @param {number} oldFirstActiveIndex
-   * @param {number} oldLastActiveIndex
-   * @param {function()} prepare
-   */
-  _partialViewportUpdate(oldFirstActiveIndex, oldLastActiveIndex, prepare) {
-    var willBeHidden = [];
-    for (var i = 0; i < this._renderedItems.length; ++i) {
-      var index = oldFirstActiveIndex + i;
-      if (index < this._firstActiveIndex || this._lastActiveIndex < index)
-        willBeHidden.push(this._renderedItems[i]);
-    }
+  _partialViewportUpdate(prepare) {
+    var itemsToRender = new Set();
+    for (var i = this._firstActiveIndex; i <= this._lastActiveIndex; ++i)
+      itemsToRender.add(this._providerElement(i));
+    var willBeHidden = this._renderedItems.filter(item => !itemsToRender.has(item));
     for (var i = 0; i < willBeHidden.length; ++i)
       willBeHidden[i].willHide();
     prepare();
     for (var i = 0; i < willBeHidden.length; ++i)
       willBeHidden[i].element().remove();
 
-    this._renderedItems = [];
+    var wasShown = [];
     var anchor = this._contentElement.firstChild;
-    var wasShown = [];
-    for (var i = this._firstActiveIndex; i <= this._lastActiveIndex; ++i) {
-      var viewportElement = this._providerElement(i);
+    for (var viewportElement of itemsToRender) {
       var element = viewportElement.element();
       if (element !== anchor) {
+        var wasReordered = element.parentElement === this._contentElement;

[lushnikov, 2017/02/15 21:34:14]

can we check for element.parentElement being null?

var shouldCallWasShown = !element.parentElement;
if (shouldCallWasShown)
    wasShown.push(viewportElement);
this._contentElement...

[luoe, 2017/02/15 23:24:18]

Done.

+        if (!wasReordered)
+          wasShown.push(viewportElement);
         this._contentElement.insertBefore(element, anchor);

[pfeldman, 2017/02/15 22:06:10]

You are breaking the console.table (wasShown contract), aren't you?

[pfeldman, 2017/02/15 22:25:58]

Element.prototype.insertBefore override seems to allow this case.

[luoe, 2017/02/15 23:24:18]

Acknowledged.

[luoe, 2017/02/15 23:24:18]

Acknowledged.

-        wasShown.push(viewportElement);
       } else {
         anchor = anchor.nextSibling;
       }
-      this._renderedItems.push(viewportElement);
     }
     for (var i = 0; i < wasShown.length; ++i)
       wasShown[i].wasShown();
+    this._renderedItems = Array.from(itemsToRender);
   }
 
   /**
    * @return {?string}
    */
   _selectedText() {
     this._updateSelectionModel(this.element.getComponentSelection());
     if (!this._headSelection || !this._anchorSelection)
       return null;
 
@@ skipping 175 matching lines @@
 Console.ConsoleViewportElement.prototype = {
   willHide() {},
 
   wasShown() {},
 
   /**
    * @return {!Element}
    */
   element() {},
 };