Tiling priorities in Android Webview.

cc/layers/picture_layer_impl.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/layers/picture_layer_impl.h"
 
 #include <algorithm>
 #include <limits>
 
 #include "base/time/time.h"
@@ skipping 381 matching lines @@
   // TODO(danakj): We should always get an occlusion tracker when we are using
   // occlusion, so update this check when we don't use a pending tree in the
   // browser compositor.
   DCHECK(!occlusion_tracker ||
          layer_tree_impl()->settings().use_occlusion_for_tile_prioritization);
 
   // Transforms and viewport are invalid for tile management inside a
   // resourceless software draw, so don't update them.
   if (!layer_tree_impl()->resourceless_software_draw()) {
     visible_rect_for_tile_priority_ = visible_content_rect();
-    viewport_size_for_tile_priority_ = layer_tree_impl()->DrawViewportSize();
+    viewport_rect_for_tile_priority_ = layer_tree_impl()->TilingViewportRect();
     screen_space_transform_for_tile_priority_ = screen_space_transform();

[aelias_OOO_until_Jul13, 2014/07/16 00:32:56]

Instead of the double-ProjectClippedRect below, wouldn't it work just as well to
multiply the TilingTransform into this matrix here?

[hush (inactive), 2014/07/16 20:45:32]

That works.
Done.

On 2014/07/16 00:32:56, aelias wrote:

   }
 
   if (!CanHaveTilings()) {
     ideal_page_scale_ = 0.f;
     ideal_device_scale_ = 0.f;
     ideal_contents_scale_ = 0.f;
     ideal_source_scale_ = 0.f;
     SanityCheckTilingState();
     return;
   }
@@ skipping 36 matching lines @@
   for (size_t i = 0; i < tilings_->num_tilings(); ++i) {
     if (tilings_->tiling_at(i)->NeedsUpdateForFrameAtTime(
             current_frame_time_in_seconds)) {
       tiling_needs_update = true;
       break;
     }
   }
   if (!tiling_needs_update)
     return;
 
-  // Use visible_content_rect, unless it's empty. If it's empty, then
-  // try to inverse project the viewport into layer space and use that.
+  // If visible_rect_for_tile_priority_ is empty or
+  // LayerTreeImpl::TilingViewportRect is set to be different from the device
+  // viewport, try to inverse project the viewport into layer space and use
+  // that. Otherwise just use visible_rect_for_tile_priority_
   gfx::Rect visible_rect_in_content_space = visible_rect_for_tile_priority_;
-  if (visible_rect_in_content_space.IsEmpty()) {
-    gfx::Transform screen_to_layer(gfx::Transform::kSkipInitialization);
-    if (screen_space_transform_for_tile_priority_.GetInverse(
-            &screen_to_layer)) {
+  if (visible_rect_in_content_space.IsEmpty() ||

[aelias_OOO_until_Jul13, 2014/07/16 00:32:56]

|| !layer_tree_impl()->TilingTransform().IsIdentity()

[hush (inactive), 2014/07/16 20:45:32]

Done.

+      layer_tree_impl()->DrawViewportSize() !=
+          layer_tree_impl()->TilingViewportRect().size()) {
+    gfx::Transform view_to_layer(gfx::Transform::kSkipInitialization);
+    gfx::Transform screen_to_view(gfx::Transform::kSkipInitialization);
+    if (screen_space_transform_for_tile_priority_.GetInverse(&view_to_layer) &&
+        layer_tree_impl()->TilingTransform().GetInverse(&screen_to_view)) {
+      // Transform the tiling viewport rect from screen to view space.
+      gfx::Rect viewport_rect_in_view_space =
+          gfx::ToEnclosingRect(MathUtil::ProjectClippedRect(
+              screen_to_view, layer_tree_impl()->TilingViewportRect()));
+
+      // Transform from view space to content space.
       visible_rect_in_content_space =
           gfx::ToEnclosingRect(MathUtil::ProjectClippedRect(
-              screen_to_layer, gfx::Rect(viewport_size_for_tile_priority_)));
+              view_to_layer, viewport_rect_in_view_space));
+
       visible_rect_in_content_space.Intersect(gfx::Rect(content_bounds()));
     }
   }
 
   gfx::Rect visible_layer_rect = gfx::ScaleToEnclosingRect(
       visible_rect_in_content_space, 1.f / contents_scale_x());
   WhichTree tree =
       layer_tree_impl()->IsActiveTree() ? ACTIVE_TREE : PENDING_TREE;
   for (size_t i = 0; i < tilings_->num_tilings(); ++i) {
     tilings_->tiling_at(i)->UpdateTilePriorities(tree,
@@ skipping 1155 matching lines @@
   return iterator_index_ < iterators_.size();
 }
 
 bool PictureLayerImpl::LayerEvictionTileIterator::IsCorrectType(
     PictureLayerTiling::TilingEvictionTileIterator* it) const {
   return it->get_type() == iteration_stage_ &&
          (**it)->required_for_activation() == required_for_activation_;
 }
 
 }  // namespace cc