[Impeller] Only set the stencil ref for StC draws. (#52006)

Another clean-up patch following
#51992.

Also, don't rely on Entity tracked stencil height for clip coverage
tracking.

impeller/aiks/canvas.cc

@@ -218,7 +218,7 @@ void Canvas::Save(bool create_subpass,
   auto entry = CanvasStackEntry{};
   entry.transform = transform_stack_.back().transform;
   entry.cull_rect = transform_stack_.back().cull_rect;
-  entry.clip_depth = transform_stack_.back().clip_depth;
+  entry.clip_height = transform_stack_.back().clip_height;
   if (create_subpass) {
     entry.rendering_mode = Entity::RenderingMode::kSubpass;
     auto subpass = std::make_unique<EntityPass>();
@@ -244,7 +244,7 @@ void Canvas::Save(bool create_subpass,
     subpass->SetBlendMode(blend_mode);
     current_pass_ = GetCurrentPass().AddSubpass(std::move(subpass));
     current_pass_->SetTransform(transform_stack_.back().transform);
-    current_pass_->SetClipDepth(transform_stack_.back().clip_depth);
+    current_pass_->SetClipDepth(transform_stack_.back().clip_height);
   }
   transform_stack_.emplace_back(entry);
 }
@@ -336,7 +336,7 @@ void Canvas::RestoreToCount(size_t count) {
 void Canvas::DrawPath(const Path& path, const Paint& paint) {
   Entity entity;
   entity.SetTransform(GetCurrentTransform());
-  entity.SetClipDepth(GetClipDepth());
+  entity.SetClipDepth(GetClipHeight());
   entity.SetBlendMode(paint.blend_mode);
   entity.SetContents(CreatePathContentsWithFilters(paint, path));
 
@@ -346,7 +346,7 @@ void Canvas::DrawPath(const Path& path, const Paint& paint) {
 void Canvas::DrawPaint(const Paint& paint) {
   Entity entity;
   entity.SetTransform(GetCurrentTransform());
-  entity.SetClipDepth(GetClipDepth());
+  entity.SetClipDepth(GetClipHeight());
   entity.SetBlendMode(paint.blend_mode);
   entity.SetContents(CreateCoverContentsWithFilters(paint));
 
@@ -427,7 +427,7 @@ bool Canvas::AttemptDrawBlurredRRect(const Rect& rect,
 
     Entity blurred_rrect_entity;
     blurred_rrect_entity.SetTransform(GetCurrentTransform());
-    blurred_rrect_entity.SetClipDepth(GetClipDepth());
+    blurred_rrect_entity.SetClipDepth(GetClipHeight());
     blurred_rrect_entity.SetBlendMode(rrect_paint.blend_mode);
 
     rrect_paint.mask_blur_descriptor = std::nullopt;
@@ -447,7 +447,7 @@ bool Canvas::AttemptDrawBlurredRRect(const Rect& rect,
       // Then, draw the non-blurred RRect on top.
       Entity entity;
       entity.SetTransform(GetCurrentTransform());
-      entity.SetClipDepth(GetClipDepth());
+      entity.SetClipDepth(GetClipHeight());
       entity.SetBlendMode(rrect_paint.blend_mode);
       entity.SetContents(CreateContentsForGeometryWithFilters(
           rrect_paint, Geometry::MakeRoundRect(rect, corner_radii)));
@@ -474,7 +474,7 @@ bool Canvas::AttemptDrawBlurredRRect(const Rect& rect,
 void Canvas::DrawLine(const Point& p0, const Point& p1, const Paint& paint) {
   Entity entity;
   entity.SetTransform(GetCurrentTransform());
-  entity.SetClipDepth(GetClipDepth());
+  entity.SetClipDepth(GetClipHeight());
   entity.SetBlendMode(paint.blend_mode);
   entity.SetContents(CreateContentsForGeometryWithFilters(
       paint, Geometry::MakeLine(p0, p1, paint.stroke_width, paint.stroke_cap)));
@@ -494,7 +494,7 @@ void Canvas::DrawRect(const Rect& rect, const Paint& paint) {
 
   Entity entity;
   entity.SetTransform(GetCurrentTransform());
-  entity.SetClipDepth(GetClipDepth());
+  entity.SetClipDepth(GetClipHeight());
   entity.SetBlendMode(paint.blend_mode);
   entity.SetContents(
       CreateContentsForGeometryWithFilters(paint, Geometry::MakeRect(rect)));
@@ -521,7 +521,7 @@ void Canvas::DrawOval(const Rect& rect, const Paint& paint) {
 
   Entity entity;
   entity.SetTransform(GetCurrentTransform());
-  entity.SetClipDepth(GetClipDepth());
+  entity.SetClipDepth(GetClipHeight());
   entity.SetBlendMode(paint.blend_mode);
   entity.SetContents(
       CreateContentsForGeometryWithFilters(paint, Geometry::MakeOval(rect)));
@@ -539,7 +539,7 @@ void Canvas::DrawRRect(const Rect& rect,
   if (paint.style == Paint::Style::kFill) {
     Entity entity;
     entity.SetTransform(GetCurrentTransform());
-    entity.SetClipDepth(GetClipDepth());
+    entity.SetClipDepth(GetClipHeight());
     entity.SetBlendMode(paint.blend_mode);
     entity.SetContents(CreateContentsForGeometryWithFilters(
         paint, Geometry::MakeRoundRect(rect, corner_radii)));
@@ -568,7 +568,7 @@ void Canvas::DrawCircle(const Point& center,
 
   Entity entity;
   entity.SetTransform(GetCurrentTransform());
-  entity.SetClipDepth(GetClipDepth());
+  entity.SetClipDepth(GetClipHeight());
   entity.SetBlendMode(paint.blend_mode);
   auto geometry =
       paint.style == Paint::Style::kStroke
@@ -680,11 +680,11 @@ void Canvas::ClipGeometry(const std::shared_ptr<Geometry>& geometry,
   Entity entity;
   entity.SetTransform(GetCurrentTransform());
   entity.SetContents(std::move(contents));
-  entity.SetClipDepth(GetClipDepth());
+  entity.SetClipDepth(GetClipHeight());
 
   GetCurrentPass().PushClip(std::move(entity));
 
-  ++transform_stack_.back().clip_depth;
+  ++transform_stack_.back().clip_height;
   ++transform_stack_.back().num_clips;
 }
 
@@ -718,8 +718,9 @@ void Canvas::RestoreClip() {
   entity.SetTransform(GetCurrentTransform());
   // This path is empty because ClipRestoreContents just generates a quad that
   // takes up the full render target.
-  entity.SetContents(std::make_shared<ClipRestoreContents>());
-  entity.SetClipDepth(GetClipDepth());
+  auto clip_restore = std::make_shared<ClipRestoreContents>();
+  clip_restore->SetRestoreHeight(GetClipHeight());
+  entity.SetContents(std::move(clip_restore));
 
   AddEntityToCurrentPass(std::move(entity));
 }
@@ -734,7 +735,7 @@ void Canvas::DrawPoints(std::vector<Point> points,
 
   Entity entity;
   entity.SetTransform(GetCurrentTransform());
-  entity.SetClipDepth(GetClipDepth());
+  entity.SetClipDepth(GetClipHeight());
   entity.SetBlendMode(paint.blend_mode);
   entity.SetContents(CreateContentsForGeometryWithFilters(
       paint,
@@ -790,7 +791,7 @@ void Canvas::DrawImageRect(const std::shared_ptr<Image>& image,
 
   Entity entity;
   entity.SetBlendMode(paint.blend_mode);
-  entity.SetClipDepth(GetClipDepth());
+  entity.SetClipDepth(GetClipHeight());
   entity.SetContents(paint.WithFilters(contents));
   entity.SetTransform(GetCurrentTransform());
 
@@ -818,8 +819,8 @@ EntityPass& Canvas::GetCurrentPass() {
   return *current_pass_;
 }
 
-size_t Canvas::GetClipDepth() const {
-  return transform_stack_.back().clip_depth;
+size_t Canvas::GetClipHeight() const {
+  return transform_stack_.back().clip_height;
 }
 
 void Canvas::AddEntityToCurrentPass(Entity entity) {
@@ -866,7 +867,7 @@ void Canvas::DrawTextFrame(const std::shared_ptr<TextFrame>& text_frame,
                            Point position,
                            const Paint& paint) {
   Entity entity;
-  entity.SetClipDepth(GetClipDepth());
+  entity.SetClipDepth(GetClipHeight());
   entity.SetBlendMode(paint.blend_mode);
 
   auto text_contents = std::make_shared<TextContents>();
@@ -918,7 +919,7 @@ void Canvas::DrawVertices(const std::shared_ptr<VerticesGeometry>& vertices,
 
   Entity entity;
   entity.SetTransform(GetCurrentTransform());
-  entity.SetClipDepth(GetClipDepth());
+  entity.SetClipDepth(GetClipHeight());
   entity.SetBlendMode(paint.blend_mode);
 
   // If there are no vertex color or texture coordinates. Or if there
@@ -1011,7 +1012,7 @@ void Canvas::DrawAtlas(const std::shared_ptr<Image>& atlas,
 
   Entity entity;
   entity.SetTransform(GetCurrentTransform());
-  entity.SetClipDepth(GetClipDepth());
+  entity.SetClipDepth(GetClipHeight());
   entity.SetBlendMode(paint.blend_mode);
   entity.SetContents(paint.WithFilters(contents));
 

impeller/aiks/canvas.h

@@ -32,7 +32,7 @@ struct CanvasStackEntry {
   Matrix transform;
   // |cull_rect| is conservative screen-space bounds of the clipped output area
   std::optional<Rect> cull_rect;
-  size_t clip_depth = 0u;
+  size_t clip_height = 0u;
   // The number of clips tracked for this canvas stack entry.
   size_t num_clips = 0u;
   Entity::RenderingMode rendering_mode = Entity::RenderingMode::kDirect;
@@ -192,7 +192,7 @@ class Canvas {
 
   EntityPass& GetCurrentPass();
 
-  size_t GetClipDepth() const;
+  size_t GetClipHeight() const;
 
   void AddEntityToCurrentPass(Entity entity);
 

impeller/entity/contents/atlas_contents.cc

@@ -240,7 +240,6 @@ bool AtlasContents::Render(const ContentContext& renderer,
         SPrintF("DrawAtlas Blend (%s)", BlendModeToString(blend_mode_)));
 #endif  // IMPELLER_DEBUG
     pass.SetVertexBuffer(vtx_builder.CreateVertexBuffer(host_buffer));
-    pass.SetStencilReference(entity.GetClipDepth());
     pass.SetPipeline(
         renderer.GetPorterDuffBlendPipeline(OptionsFromPass(pass)));
 
@@ -410,7 +409,6 @@ bool AtlasTextureContents::Render(const ContentContext& renderer,
 
   auto options = OptionsFromPassAndEntity(pass, entity);
   pass.SetPipeline(renderer.GetTexturePipeline(options));
-  pass.SetStencilReference(entity.GetClipDepth());
   pass.SetVertexBuffer(vertex_builder.CreateVertexBuffer(host_buffer));
   VS::BindFrameInfo(pass, host_buffer.EmplaceUniform(frame_info));
   FS::BindTextureSampler(pass, texture,
@@ -498,7 +496,6 @@ bool AtlasColorContents::Render(const ContentContext& renderer,
   auto opts = OptionsFromPassAndEntity(pass, entity);
   opts.blend_mode = BlendMode::kSourceOver;
   pass.SetPipeline(renderer.GetGeometryColorPipeline(opts));
-  pass.SetStencilReference(entity.GetClipDepth());
   pass.SetVertexBuffer(vertex_builder.CreateVertexBuffer(host_buffer));
   VS::BindFrameInfo(pass, host_buffer.EmplaceUniform(frame_info));
   FS::BindFragInfo(pass, host_buffer.EmplaceUniform(frag_info));

impeller/entity/contents/clip_contents.cc

@@ -191,6 +191,14 @@ ClipRestoreContents::ClipRestoreContents() = default;
 
 ClipRestoreContents::~ClipRestoreContents() = default;
 
+void ClipRestoreContents::SetRestoreHeight(size_t clip_height) {
+  restore_height_ = clip_height;
+}
+
+size_t ClipRestoreContents::GetRestoreHeight() const {
+  return restore_height_;
+}
+
 void ClipRestoreContents::SetRestoreCoverage(
     std::optional<Rect> restore_coverage) {
   restore_coverage_ = restore_coverage;
@@ -230,7 +238,7 @@ bool ClipRestoreContents::Render(const ContentContext& renderer,
   options.stencil_mode = ContentContextOptions::StencilMode::kLegacyClipRestore;
   options.primitive_type = PrimitiveType::kTriangleStrip;
   pass.SetPipeline(renderer.GetClipPipeline(options));
-  pass.SetStencilReference(entity.GetClipDepth());
+  pass.SetStencilReference(0);
 
   // Create a rect that covers either the given restore area, or the whole
   // render target texture.

impeller/entity/contents/clip_contents.h

@@ -63,6 +63,10 @@ class ClipRestoreContents final : public Contents {
 
   ~ClipRestoreContents();
 
+  void SetRestoreHeight(size_t clip_height);
+
+  size_t GetRestoreHeight() const;
+
   /// @brief  The area on the pass texture where this clip restore will be
   ///         applied. If unset, the entire pass texture will be restored.
   ///
@@ -94,6 +98,7 @@ class ClipRestoreContents final : public Contents {
 
  private:
   std::optional<Rect> restore_coverage_;
+  size_t restore_height_ = 0;
 
   ClipRestoreContents(const ClipRestoreContents&) = delete;
 

impeller/entity/contents/color_source_contents.h

@@ -229,7 +229,6 @@ class ColorSourceContents : public Contents {
       auto restore = ClipRestoreContents();
       restore.SetRestoreCoverage(GetCoverage(entity));
       Entity restore_entity = entity.Clone();
-      restore_entity.SetClipDepth(0);
       return restore.Render(renderer, restore_entity, pass);
     }
     return true;

impeller/entity/contents/filters/blend_filter_contents.cc

@@ -111,16 +111,14 @@ static std::optional<Entity> AdvancedBlend(
       if (!dst_snapshot.has_value()) {
         return std::nullopt;
       }
-      return Entity::FromSnapshot(dst_snapshot.value(), entity.GetBlendMode(),
-                                  entity.GetClipDepth());
+      return Entity::FromSnapshot(dst_snapshot.value(), entity.GetBlendMode());
     }
     auto maybe_src_uvs = src_snapshot->GetCoverageUVs(coverage);
     if (!maybe_src_uvs.has_value()) {
       if (!dst_snapshot.has_value()) {
         return std::nullopt;
       }
-      return Entity::FromSnapshot(dst_snapshot.value(), entity.GetBlendMode(),
-                                  entity.GetClipDepth());
+      return Entity::FromSnapshot(dst_snapshot.value(), entity.GetBlendMode());
     }
     src_uvs = maybe_src_uvs.value();
   }
@@ -253,7 +251,7 @@ static std::optional<Entity> AdvancedBlend(
                           ? 1.0f
                           : dst_snapshot->opacity) *
                      alpha.value_or(1.0)},
-      entity.GetBlendMode(), entity.GetClipDepth());
+      entity.GetBlendMode());
 }
 
 std::optional<Entity> BlendFilterContents::CreateForegroundAdvancedBlend(
@@ -295,7 +293,6 @@ std::optional<Entity> BlendFilterContents::CreateForegroundAdvancedBlend(
                                  BlendModeToString(blend_mode)));
 #endif  // IMPELLER_DEBUG
     pass.SetVertexBuffer(std::move(vtx_buffer));
-    pass.SetStencilReference(entity.GetClipDepth());
     auto options = OptionsFromPass(pass);
     options.primitive_type = PrimitiveType::kTriangleStrip;
 
@@ -397,7 +394,6 @@ std::optional<Entity> BlendFilterContents::CreateForegroundAdvancedBlend(
 
   Entity sub_entity;
   sub_entity.SetContents(std::move(contents));
-  sub_entity.SetClipDepth(entity.GetClipDepth());
 
   return sub_entity;
 }
@@ -422,8 +418,7 @@ std::optional<Entity> BlendFilterContents::CreateForegroundPorterDuffBlend(
   }
 
   if (blend_mode == BlendMode::kDestination) {
-    return Entity::FromSnapshot(dst_snapshot.value(), entity.GetBlendMode(),
-                                entity.GetClipDepth());
+    return Entity::FromSnapshot(dst_snapshot.value(), entity.GetBlendMode());
   }
 
   RenderProc render_proc = [foreground_color, dst_snapshot, blend_mode,
@@ -450,7 +445,6 @@ std::optional<Entity> BlendFilterContents::CreateForegroundPorterDuffBlend(
                                  BlendModeToString(blend_mode)));
 #endif  // IMPELLER_DEBUG
     pass.SetVertexBuffer(std::move(vtx_buffer));
-    pass.SetStencilReference(entity.GetClipDepth());
     auto options = OptionsFromPass(pass);
     options.primitive_type = PrimitiveType::kTriangleStrip;
     pass.SetPipeline(renderer.GetPorterDuffBlendPipeline(options));
@@ -501,7 +495,6 @@ std::optional<Entity> BlendFilterContents::CreateForegroundPorterDuffBlend(
 
   Entity sub_entity;
   sub_entity.SetContents(std::move(contents));
-  sub_entity.SetClipDepth(entity.GetClipDepth());
 
   return sub_entity;
 }
@@ -667,7 +660,7 @@ static std::optional<Entity> PipelineBlend(
                           ? 1.0f
                           : dst_snapshot->opacity) *
                      alpha.value_or(1.0)},
-      entity.GetBlendMode(), entity.GetClipDepth());
+      entity.GetBlendMode());
 }
 
 #define BLEND_CASE(mode)                                                      \

impeller/entity/contents/filters/border_mask_blur_filter_contents.cc

@@ -118,7 +118,6 @@ std::optional<Entity> BorderMaskBlurFilterContents::RenderFilter(
     pass.SetCommandLabel("Border Mask Blur Filter");
     pass.SetPipeline(renderer.GetBorderMaskBlurPipeline(options));
     pass.SetVertexBuffer(vtx_builder.CreateVertexBuffer(host_buffer));
-    pass.SetStencilReference(entity.GetClipDepth());
 
     FS::BindFragInfo(pass, host_buffer.EmplaceUniform(frag_info));
     VS::BindFrameInfo(pass, host_buffer.EmplaceUniform(frame_info));
@@ -139,7 +138,6 @@ std::optional<Entity> BorderMaskBlurFilterContents::RenderFilter(
 
   Entity sub_entity;
   sub_entity.SetContents(std::move(contents));
-  sub_entity.SetClipDepth(entity.GetClipDepth());
   sub_entity.SetBlendMode(entity.GetBlendMode());
   return sub_entity;
 }

impeller/entity/contents/filters/color_matrix_filter_contents.cc

@@ -56,7 +56,6 @@ std::optional<Entity> ColorMatrixFilterContents::RenderFilter(
                                const ContentContext& renderer,
                                const Entity& entity, RenderPass& pass) -> bool {
     pass.SetCommandLabel("Color Matrix Filter");
-    pass.SetStencilReference(entity.GetClipDepth());
 
     auto options = OptionsFromPassAndEntity(pass, entity);
     options.primitive_type = PrimitiveType::kTriangleStrip;
@@ -116,7 +115,6 @@ std::optional<Entity> ColorMatrixFilterContents::RenderFilter(
 
   Entity sub_entity;
   sub_entity.SetContents(std::move(contents));
-  sub_entity.SetClipDepth(entity.GetClipDepth());
   sub_entity.SetBlendMode(entity.GetBlendMode());
   return sub_entity;
 }