Bug 538571 - checkerboard appears after slow pan [r=stuart,vingtetun,froystig]

mobile/chrome/content/BrowserView.js

@@ -244,6 +244,9 @@ BrowserView.prototype = {
     let cacheSize = kBrowserViewCacheSize;
     try {
       cacheSize = gPrefService.getIntPref("tile.cache.size");
+      // XXX cacheSize still can be -1 even though new profile sets it to a positive value
+      if (cacheSize == -1)
+        cacheSize = kBrowserViewCacheSize;
     } catch(e) {}
     
     this._tileManager = new TileManager(this._appendTile, this._removeTile, this, cacheSize);
@@ -863,35 +866,32 @@ BrowserView.BrowserViewportState.prototype = {
  */
 BrowserView.IdleServiceObserver = function IdleServiceObserver(browserView) {
   this._browserView = browserView;
-  this._crawlStarted = false;
-  this._idleState = false;
+  this._idle = false;
+  this._paused = false;
 };
 
 BrowserView.IdleServiceObserver.prototype = {
-  /** Start prefetching tiles. */
-  _start: function _start() {
-    if (!this._crawlStarted) {
-      let bv = this._browserView;
-      bv._tileManager.restartPrefetchCrawl();
-      this._crawlStarted = true;
-    }
+  /** No matter what idle is, make sure prefetching is not active. */
+  pause: function pause() {
+    this._paused = true;
+    this._updateTileManager();
   },
 
-  /** Stop prefetching tiles. */
-  _stop: function _stop() {
-    if (this._crawlStarted) {
-      let bv = this._browserView;
-      bv._tileManager.stopPrefetchCrawl();
-      this._crawlStarted = false;
-    }
+  /** Prefetch tiles in idle mode. */
+  resume: function resume() {
+    this._paused = false;
+    this._updateTileManager();
   },
 
   /** Idle event handler. */
   observe: function observe(aSubject, aTopic, aUserIdleTime) {
-    this._idleState = (aTopic == "idle") ? true : false;
-    if (this._idleState)
-      this._start();
-    else
-      this._stop();
+    this._idle = (aTopic == "idle") ? true : false;
+    this._updateTileManager();
   },
+
+  _updateTileManager: function _updateTileManager() {
+    let bv = this._browserView;
+    bv._tileManager.setPrefetch(this._idle && !this._paused);
+  }
 };
+

mobile/chrome/content/TileManager.js.in

@@ -136,6 +136,9 @@ function TileManager(appendTile, removeTile, browserView, cacheSize) {
   /* remember these values to reduce the recenterEvictionQueue cost */
   this._ctr = new Point(0, 0);
 
+  /* If true, render dirty tiles outside of a viewport on timer. */
+  this._prefetch = false;
+
   /* create one Image of the checkerboard to be reused */
   this._checkerboard = new Image();
   this._checkerboard.src = "chrome://browser/content/checkerboard.png";
@@ -360,6 +363,17 @@ TileManager.prototype = {
       this.criticalRectPaint();
   },
 
+  setPrefetch: function setPrefetch(prefetch) {
+    if (prefetch == this._prefetch)
+      return;
+
+   this._prefetch = prefetch;
+    if (prefetch)
+      this.restartPrefetchCrawl();
+    else
+      this.stopPrefetchCrawl();
+  },
+
   restartPrefetchCrawl: function restartPrefetchCrawl(startRectOrQueue) {
     if (startRectOrQueue instanceof Array) {
       this._crawler = new TileManager.CrawlIterator(this._tileCache);
@@ -371,7 +385,7 @@ TileManager.prototype = {
     } else {
       let cr = this._criticalRect;
       this._crawler = new TileManager.CrawlIterator(this._tileCache,
-                                                    startRectOrQueue || (cr ? cr.clone() : null));
+                                                    startRectOrQueue || (!cr.isEmpty() ? cr.clone() : null));
     }
 
     if (!this._idleTileCrawlerTimeout)
@@ -523,6 +537,7 @@ TileManager.prototype = {
       if (tile.isDirty()) {
         self._renderTile(tile);
       }
+      self._appendTileSafe(tile);
     }
 
     if (comeAgain) {

mobile/chrome/content/browser.js

@@ -1416,6 +1416,12 @@ Browser.MainDragger.prototype = {
       this.draggedFrame = element.ownerDocument.defaultView;
 
     this.bv.pauseRendering();
+
+    // XXX shouldn't know about observer
+    // adding pause in pauseRendering isn't so great, because tiles will hardly ever prefetch while
+    // loading state is going (and already, the idle timer is bigger during loading so it doesn't fit
+    // into the aggressive flag).
+    this.bv._idleServiceObserver.pause();
   },
 
   dragStop: function dragStop(dx, dy, scroller) {
@@ -1425,6 +1431,9 @@ Browser.MainDragger.prototype = {
     Browser.tryUnfloatToolbar();
 
     this.bv.resumeRendering();
+
+    // XXX shouldn't know about observer
+    this.bv._idleServiceObserver.resume();
   },
 
   dragMove: function dragMove(dx, dy, scroller) {