Changeset 109112 in webkit

Timestamp:

Feb 28, 2012 8:52:35 AM (12 years ago)

Author:

kenneth@webkit.org

Message:

Improve the visual of the tiling
​https://bugs.webkit.org/show_bug.cgi?id=79648

Reviewed by Noam Rosenthal.

When we cover the view with tiles[1], we do so from the center
and out, in bigger and bigger cicles by finding the current minimum
covered distance.

This looks like painting a rect, then a cross, then a rect, ...
and can be noticed when a page blocks during tiling.

We can do this better by only covering with tiles in rects at a time.

The original code was done so that it gave preference to tiles in
vertical direction due to that being the most common scrolling
direction. This is not needed anymore as we are now using the
trajectory vector when panning, which always gives preference for
creating tiles in the panned direction.

[1] It should be noted that we always cover the visibleRect in one go,

and that we here are talking about covering the coverRect beyond
the visibleRect

• platform/graphics/TiledBackingStore.cpp:

(WebCore::TiledBackingStore::tileDistance):

Location:

trunk/Source/WebCore

Files:

• ChangeLog (modified) (1 diff)
• platform/graphics/TiledBackingStore.cpp (modified) (1 diff)

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2012-02-28  Kenneth Rohde Christiansen  <kenneth@webkit.org>
+
+        Improve the visual of the tiling
+        https://bugs.webkit.org/show_bug.cgi?id=79648
+
+        Reviewed by Noam Rosenthal.
+
+        When we cover the view with tiles[1], we do so from the center
+        and out, in bigger and bigger cicles by finding the current minimum
+        covered distance.
+
+        This looks like painting a rect, then a cross, then a rect, ...
+        and can be noticed when a page blocks during tiling.
+
+        We can do this better by only covering with tiles in rects at a time.
+
+        The original code was done so that it gave preference to tiles in
+        vertical direction due to that being the most common scrolling
+        direction. This is not needed anymore as we are now using the
+        trajectory vector when panning, which always gives preference for
+        creating tiles in the panned direction.
+
+        [1] It should be noted that we always cover the visibleRect in one go,
+            and that we here are talking about covering the coverRect beyond
+            the visibleRect
+
+        * platform/graphics/TiledBackingStore.cpp:
+        (WebCore::TiledBackingStore::tileDistance):
+
 2012-02-28  Yury Semikhatsky  <yurys@chromium.org>
 

trunk/Source/WebCore/platform/graphics/TiledBackingStore.cpp

@@ -194 +194 @@
     if (viewport.intersects(tileRectForCoordinate(tileCoordinate)))
         return 0;
-    
+
     IntPoint viewCenter = viewport.location() + IntSize(viewport.width() / 2, viewport.height() / 2);
     Tile::Coordinate centerCoordinate = tileCoordinateForPoint(viewCenter);
-    
-    // Manhattan distance, biased so that vertical distances are shorter.
-    const double horizontalBias = 1.3;
-    return abs(centerCoordinate.y() - tileCoordinate.y()) + horizontalBias * abs(centerCoordinate.x() - tileCoordinate.x());
+
+    return std::max(abs(centerCoordinate.y() - tileCoordinate.y()), abs(centerCoordinate.x() - tileCoordinate.x()));
 }