[DisplayList] track unbounded state on save layers and DisplayLists (f…

…lutter#54032)

New flags on SaveLayerOptions will report if a saveLayer result is unbounded because a rendering operation within its contents did not have a definable bounds and there was no clip installed at the time (consider DrawPaint for example). A similar flag is found on DisplayList objects which reports if their top level had an unbounded operation.

display_list/BUILD.gn

@@ -130,6 +130,7 @@ if (enable_unittests) {
       ":display_list",
       ":display_list_fixtures",
       "//flutter/display_list/testing:display_list_testing",
+      "//flutter/impeller/typographer/backends/skia:typographer_skia_backend",
       "//flutter/testing",
       "//flutter/testing:skia",
     ]

display_list/display_list.cc

@@ -26,6 +26,7 @@ DisplayList::DisplayList()
       is_ui_thread_safe_(true),
       modifies_transparent_black_(false),
       root_has_backdrop_filter_(false),
+      root_is_unbounded_(false),
       max_root_blend_mode_(DlBlendMode::kClear) {}
 
 DisplayList::DisplayList(DisplayListStorage&& storage,
@@ -40,6 +41,7 @@ DisplayList::DisplayList(DisplayListStorage&& storage,
                          bool modifies_transparent_black,
                          DlBlendMode max_root_blend_mode,
                          bool root_has_backdrop_filter,
+                         bool root_is_unbounded,
                          sk_sp<const DlRTree> rtree)
     : storage_(std::move(storage)),
       byte_count_(byte_count),
@@ -53,6 +55,7 @@ DisplayList::DisplayList(DisplayListStorage&& storage,
       is_ui_thread_safe_(is_ui_thread_safe),
       modifies_transparent_black_(modifies_transparent_black),
       root_has_backdrop_filter_(root_has_backdrop_filter),
+      root_is_unbounded_(root_is_unbounded),
       max_root_blend_mode_(max_root_blend_mode),
       rtree_(std::move(rtree)) {}
 

display_list/display_list.h

@@ -216,6 +216,13 @@ class SaveLayerOptions {
     return options;
   }
 
+  bool content_is_unbounded() const { return fContentIsUnbounded; }
+  SaveLayerOptions with_content_is_unbounded() const {
+    SaveLayerOptions options(this);
+    options.fContentIsUnbounded = true;
+    return options;
+  }
+
   SaveLayerOptions& operator=(const SaveLayerOptions& other) {
     flags_ = other.flags_;
     return *this;
@@ -235,6 +242,7 @@ class SaveLayerOptions {
       unsigned fBoundsFromCaller : 1;
       unsigned fContentIsClipped : 1;
       unsigned fHasBackdropFilter : 1;
+      unsigned fContentIsUnbounded : 1;
     };
     uint32_t flags_;
   };
@@ -331,6 +339,18 @@ class DisplayList : public SkRefCnt {
   /// be required for the backdrop filter to do its work.
   bool root_has_backdrop_filter() const { return root_has_backdrop_filter_; }
 
+  /// @brief    Indicates if a rendering operation at the root level of the
+  ///           DisplayList had an unbounded result, not otherwise limited by
+  ///           a clip operation.
+  ///
+  /// This condition can occur in a number of situations. The most common
+  /// situation is when there is a drawPaint or drawColor rendering
+  /// operation which fills out the entire drawable surface unless it is
+  /// bounded by a clip. Other situations include an operation rendered
+  /// through an ImageFilter that cannot compute the resulting bounds or
+  /// when an unclipped backdrop filter is applied by a save layer.
+  bool root_is_unbounded() const { return root_is_unbounded_; }
+
   /// @brief    Indicates the maximum DlBlendMode used on any rendering op
   ///           in the root surface of the DisplayList.
   ///
@@ -353,6 +373,7 @@ class DisplayList : public SkRefCnt {
               bool modifies_transparent_black,
               DlBlendMode max_root_blend_mode,
               bool root_has_backdrop_filter,
+              bool root_is_unbounded,
               sk_sp<const DlRTree> rtree);
 
   static uint32_t next_unique_id();
@@ -375,6 +396,7 @@ class DisplayList : public SkRefCnt {
   const bool is_ui_thread_safe_;
   const bool modifies_transparent_black_;
   const bool root_has_backdrop_filter_;
+  const bool root_is_unbounded_;
   const DlBlendMode max_root_blend_mode_;
 
   const sk_sp<const DlRTree> rtree_;