DisplayList SaveLayer (and root layer) read-back flags

display_list/display_list.cc

@@ -24,7 +24,9 @@ DisplayList::DisplayList()
       bounds_({0, 0, 0, 0}),
       can_apply_group_opacity_(true),
       is_ui_thread_safe_(true),
-      modifies_transparent_black_(false) {}
+      modifies_transparent_black_(false),
+      root_has_backdrop_filter_(false),
+      max_root_blend_mode_(DlBlendMode::kClear) {}
 
 DisplayList::DisplayList(DisplayListStorage&& storage,
                          size_t byte_count,
@@ -36,6 +38,8 @@ DisplayList::DisplayList(DisplayListStorage&& storage,
                          bool can_apply_group_opacity,
                          bool is_ui_thread_safe,
                          bool modifies_transparent_black,
+                         DlBlendMode max_root_blend_mode,
+                         bool root_has_backdrop_filter,
                          sk_sp<const DlRTree> rtree)
     : storage_(std::move(storage)),
       byte_count_(byte_count),
@@ -48,6 +52,8 @@ DisplayList::DisplayList(DisplayListStorage&& storage,
       can_apply_group_opacity_(can_apply_group_opacity),
       is_ui_thread_safe_(is_ui_thread_safe),
       modifies_transparent_black_(modifies_transparent_black),
+      root_has_backdrop_filter_(root_has_backdrop_filter),
+      max_root_blend_mode_(max_root_blend_mode),
       rtree_(std::move(rtree)) {}
 
 DisplayList::~DisplayList() {

display_list/display_list.h

@@ -8,6 +8,7 @@
 #include <memory>
 #include <optional>
 
+#include "flutter/display_list/dl_blend_mode.h"
 #include "flutter/display_list/dl_sampling_options.h"
 #include "flutter/display_list/geometry/dl_rtree.h"
 #include "flutter/fml/logging.h"
@@ -208,6 +209,13 @@ class SaveLayerOptions {
     return options;
   }
 
+  bool contains_backdrop_filter() const { return fHasBackdropFilter; }
+  SaveLayerOptions with_contains_backdrop_filter() const {
+    SaveLayerOptions options(this);
+    options.fHasBackdropFilter = true;
+    return options;
+  }
+
   SaveLayerOptions& operator=(const SaveLayerOptions& other) {
     flags_ = other.flags_;
     return *this;
@@ -226,6 +234,7 @@ class SaveLayerOptions {
       unsigned fCanDistributeOpacity : 1;
       unsigned fBoundsFromCaller : 1;
       unsigned fContentIsClipped : 1;
+      unsigned fHasBackdropFilter : 1;
     };
     uint32_t flags_;
   };
@@ -313,6 +322,24 @@ class DisplayList : public SkRefCnt {
 
   const DisplayListStorage& GetStorage() const { return storage_; }
 
+  /// @brief    Indicates if there are any saveLayer operations at the root
+  ///           surface level of the DisplayList that use a backdrop filter.
+  ///
+  /// This condition can be used to determine what kind of surface to create
+  /// for the root layer into which to render the DisplayList as some GPUs
+  /// can support surfaces that do or do not support the readback that would
+  /// be required for the backdrop filter to do its work.
+  bool root_has_backdrop_filter() const { return root_has_backdrop_filter_; }
+
+  /// @brief    Indicates the maximum DlBlendMode used on any rendering op
+  ///           in the root surface of the DisplayList.
+  ///
+  /// This condition can be used to determine what kind of surface to create
+  /// for the root layer into which to render the DisplayList as some GPUs
+  /// can support surfaces that do or do not support the readback that would
+  /// be required for the indicated blend mode to do its work.
+  DlBlendMode max_root_blend_mode() const { return max_root_blend_mode_; }
+
  private:
   DisplayList(DisplayListStorage&& ptr,
               size_t byte_count,
@@ -324,6 +351,8 @@ class DisplayList : public SkRefCnt {
               bool can_apply_group_opacity,
               bool is_ui_thread_safe,
               bool modifies_transparent_black,
+              DlBlendMode max_root_blend_mode,
+              bool root_has_backdrop_filter,
               sk_sp<const DlRTree> rtree);
 
   static uint32_t next_unique_id();
@@ -345,6 +374,8 @@ class DisplayList : public SkRefCnt {
   const bool can_apply_group_opacity_;
   const bool is_ui_thread_safe_;
   const bool modifies_transparent_black_;
+  const bool root_has_backdrop_filter_;
+  const DlBlendMode max_root_blend_mode_;
 
   const sk_sp<const DlRTree> rtree_;