impeller::Contents Class Reference

#include <contents.h>

Inheritance diagram for impeller::Contents:

Classes
struct	ClipCoverage

Public Types
using	ColorFilterProc = std::function< Color(Color)>
using	RenderProc = std::function< bool(const ContentContext &renderer, const Entity &entity, RenderPass &pass)>
using	CoverageProc = std::function< std::optional< Rect >(const Entity &entity)>

Public Member Functions
	Contents ()
virtual	~Contents ()
virtual void	PopulateGlyphAtlas (const std::shared_ptr< LazyGlyphAtlas > &lazy_glyph_atlas, Scalar scale)
	Add any text data to the specified lazy atlas. The scale parameter must be used again later when drawing the text.
virtual bool	Render (const ContentContext &renderer, const Entity &entity, RenderPass &pass) const =0
virtual std::optional< Rect >	GetCoverage (const Entity &entity) const =0
	Get the area of the render pass that will be affected when this contents is rendered.
void	SetCoverageHint (std::optional< Rect > coverage_hint)
	Hint that specifies the coverage area of this Contents that will actually be used during rendering. This is for optimization purposes only and can not be relied on as a clip. May optionally affect the result of GetCoverage().
const std::optional< Rect > &	GetCoverageHint () const
virtual bool	IsOpaque () const
	Whether this Contents only emits opaque source colors from the fragment stage. This value does not account for any entity properties (e.g. the blend mode), clips/visibility culling, or inherited opacity.
virtual ClipCoverage	GetClipCoverage (const Entity &entity, const std::optional< Rect > &current_clip_coverage) const
	Given the current pass space bounding rectangle of the clip buffer, return the expected clip coverage after this draw call. This should only be implemented for contents that may write to the clip buffer.
virtual std::optional< Snapshot >	RenderToSnapshot (const ContentContext &renderer, const Entity &entity, std::optional< Rect > coverage_limit=std::nullopt, const std::optional< SamplerDescriptor > &sampler_descriptor=std::nullopt, bool msaa_enabled=true, int32_t mip_count=1, const std::string &label="Snapshot") const
	Render this contents to a snapshot, respecting the entity's transform, path, clip depth, and blend mode. The result texture size is always the size of GetCoverage(entity).
virtual bool	ShouldRender (const Entity &entity, const std::optional< Rect > clip_coverage) const
std::optional< Size >	GetColorSourceSize () const
	Return the color source's intrinsic size, if available.
void	SetColorSourceSize (Size size)
virtual bool	CanInheritOpacity (const Entity &entity) const
	Whether or not this contents can accept the opacity peephole optimization.
virtual void	SetInheritedOpacity (Scalar opacity)
	Inherit the provided opacity.
virtual std::optional< Color >	AsBackgroundColor (const Entity &entity, ISize target_size) const
	Returns a color if this Contents will flood the given target_size with a color. This output color is the "Source" color that will be used for the Entity's blend operation.
virtual const FilterContents *	AsFilter () const
	Cast to a filter. Returns nullptr if this Contents is not a filter.
virtual bool	ApplyColorFilter (const ColorFilterProc &color_filter_proc)
	If possible, applies a color filter to this contents inputs on the CPU.

Static Public Member Functions
static std::shared_ptr< Contents >	MakeAnonymous (RenderProc render_proc, CoverageProc coverage_proc)

Detailed Description

Definition at line 34 of file contents.h.

Member Typedef Documentation

ColorFilterProc

using impeller::Contents::ColorFilterProc = std::function<Color(Color)>

A procedure that filters a given unpremultiplied color to produce a new unpremultiplied color.

Definition at line 38 of file contents.h.

CoverageProc

using impeller::Contents::CoverageProc = std::function<std::optional<Rect>(const Entity& entity)>

Definition at line 50 of file contents.h.

RenderProc

using impeller::Contents::RenderProc = std::function<bool(const ContentContext& renderer, const Entity& entity, RenderPass& pass)>

Definition at line 47 of file contents.h.

Constructor & Destructor Documentation

Contents()

impeller::Contents::Contents ( )

default

~Contents()

impeller::Contents::~Contents ( )

virtualdefault

Member Function Documentation

ApplyColorFilter()

bool impeller::Contents::ApplyColorFilter ( const ColorFilterProc &  color_filter_proc )

virtual

If possible, applies a color filter to this contents inputs on the CPU.

This method will either fully apply the color filter or perform no action. Partial/incorrect application of the color filter will never occur.

Parameters

[in]

color_filter_proc

A function that filters a given unpremultiplied color to produce a new unpremultiplied color.

Returns

True if the color filter was able to be fully applied to all all relevant inputs. Otherwise, this operation is a no-op and false is returned.

Reimplemented in impeller::ConicalGradientContents, impeller::LinearGradientContents, impeller::RadialGradientContents, impeller::SolidColorContents, impeller::SolidRRectBlurContents, and impeller::SweepGradientContents.

Definition at line 150 of file contents.cc.

                                                      {
  return false;
}

AsBackgroundColor()

std::optional< Color > impeller::Contents::AsBackgroundColor ( const Entity &  entity, ISize  target_size  ) const

virtual

Returns a color if this Contents will flood the given target_size with a color. This output color is the "Source" color that will be used for the Entity's blend operation.

This is useful for absorbing full screen solid color draws into subpass clear colors.

Reimplemented in impeller::SolidColorContents.

Definition at line 141 of file contents.cc.

                                                                          {
  return {};
}

AsFilter()

const FilterContents * impeller::Contents::AsFilter ( ) const

virtual

Cast to a filter. Returns nullptr if this Contents is not a filter.

Reimplemented in impeller::FilterContents.

Definition at line 146 of file contents.cc.

                                               {
  return nullptr;
}

CanInheritOpacity()

bool impeller::Contents::CanInheritOpacity ( const Entity &  entity ) const

virtual

Whether or not this contents can accept the opacity peephole optimization.

By default all contents return false. Contents are responsible for determining whether or not their own geometries intersect in a way that makes accepting opacity impossible. It is always safe to return false, especially if computing overlap would be computationally expensive.

Reimplemented in impeller::ClipContents, impeller::ClipRestoreContents, impeller::ColorSourceContents, impeller::RuntimeEffectContents, impeller::TextContents, and impeller::TextureContents.

Definition at line 132 of file contents.cc.

                                                           {
  return false;
}

GetClipCoverage()

Contents::ClipCoverage impeller::Contents::GetClipCoverage ( const Entity &  entity, const std::optional< Rect > &  current_clip_coverage  ) const

virtual

Given the current pass space bounding rectangle of the clip buffer, return the expected clip coverage after this draw call. This should only be implemented for contents that may write to the clip buffer.

During rendering, coverage coordinates count pixels from the top left corner of the framebuffer.

Reimplemented in impeller::ClipContents, and impeller::ClipRestoreContents.

Definition at line 57 of file contents.cc.

                                                          {
  return {.type = ClipCoverage::Type::kNoChange,
          .coverage = current_clip_coverage};
}

GetColorSourceSize()

std::optional< Size > impeller::Contents::GetColorSourceSize

(

)

const

Return the color source's intrinsic size, if available.

    For example, a gradient has a size based on its end and beginning
    points, ignoring any tiling. Solid colors and runtime effects have
    no size.

Definition at line 178 of file contents.cc.

                                                     {
  return color_source_size_;
};

GetCoverage()

virtual std::optional< Rect > impeller::Contents::GetCoverage ( const Entity &  entity ) const

pure virtual

Get the area of the render pass that will be affected when this contents is rendered.

During rendering, coverage coordinates count pixels from the top left corner of the framebuffer.

Returns

The coverage rectangle. An std::nullopt result means that rendering this contents has no effect on the output color.

Implemented in impeller::AnonymousContents, impeller::AtlasContents, impeller::CheckerboardContents, impeller::ClipContents, impeller::ClipRestoreContents, impeller::ColorSourceContents, impeller::FilterContents, impeller::FramebufferBlendContents, impeller::SolidColorContents, impeller::SolidRRectBlurContents, impeller::TextContents, impeller::TextureContents, and impeller::VerticesSimpleBlendContents.

GetCoverageHint()

const std::optional< Rect > & impeller::Contents::GetCoverageHint

(

)

const

Definition at line 174 of file contents.cc.

                                                         {
  return coverage_hint_;
}

IsOpaque()

bool impeller::Contents::IsOpaque ( ) const

virtual

Whether this Contents only emits opaque source colors from the fragment stage. This value does not account for any entity properties (e.g. the blend mode), clips/visibility culling, or inherited opacity.

Reimplemented in impeller::LinearGradientContents, impeller::RadialGradientContents, impeller::SolidColorContents, impeller::SweepGradientContents, and impeller::TiledTextureContents.

Definition at line 53 of file contents.cc.

                              {
  return false;
}

MakeAnonymous()

std::shared_ptr< Contents > impeller::Contents::MakeAnonymous ( Contents::RenderProc  render_proc, Contents::CoverageProc  coverage_proc  )

static

Definition at line 42 of file contents.cc.

                                        {
  return AnonymousContents::Make(std::move(render_proc),
                                 std::move(coverage_proc));
}

PopulateGlyphAtlas()

virtual void impeller::Contents::PopulateGlyphAtlas ( const std::shared_ptr< LazyGlyphAtlas > &  lazy_glyph_atlas, Scalar  scale  )

inlinevirtual

Add any text data to the specified lazy atlas. The scale parameter must be used again later when drawing the text.

Reimplemented in impeller::FilterContents, and impeller::TextContents.

Definition at line 61 of file contents.h.

                    {}

Render()

virtual bool impeller::Contents::Render ( const ContentContext &  renderer, const Entity &  entity, RenderPass &  pass  ) const

pure virtual

Implemented in impeller::AnonymousContents, impeller::AtlasContents, impeller::CheckerboardContents, impeller::ClipContents, impeller::ClipRestoreContents, impeller::ConicalGradientContents, impeller::FilterContents, impeller::FramebufferBlendContents, impeller::LinearGradientContents, impeller::RadialGradientContents, impeller::RuntimeEffectContents, impeller::SceneContents, impeller::SolidColorContents, impeller::SolidRRectBlurContents, impeller::SweepGradientContents, impeller::TextContents, impeller::TextureContents, impeller::TiledTextureContents, and impeller::VerticesSimpleBlendContents.

RenderToSnapshot()

std::optional< Snapshot > impeller::Contents::RenderToSnapshot ( const ContentContext &  renderer, const Entity &  entity, std::optional< Rect >  coverage_limit = std::nullopt, const std::optional< SamplerDescriptor > &  sampler_descriptor = std::nullopt, bool  msaa_enabled = true, int32_t  mip_count = 1, const std::string &  label = "Snapshot"  ) const

virtual

Render this contents to a snapshot, respecting the entity's transform, path, clip depth, and blend mode. The result texture size is always the size of GetCoverage(entity).

Reimplemented in impeller::FilterContents, impeller::TextureContents, and impeller::TiledTextureContents.

Definition at line 64 of file contents.cc.

                                  {
  auto coverage = GetCoverage(entity);
  if (!coverage.has_value()) {
    return std::nullopt;
  }
 
  std::shared_ptr<CommandBuffer> command_buffer =
      renderer.GetContext()->CreateCommandBuffer();
  if (!command_buffer) {
    return std::nullopt;
  }
 
  // Pad Contents snapshots with 1 pixel borders to ensure correct sampling
  // behavior. Not doing so results in a coverage leak for filters that support
  // customizing the input sampling mode. Snapshots of contents should be
  // theoretically treated as infinite size just like layers.
  coverage = coverage->Expand(1);
 
  if (coverage_limit.has_value()) {
    coverage = coverage->Intersection(*coverage_limit);
    if (!coverage.has_value()) {
      return std::nullopt;
    }
  }
 
  ISize subpass_size = ISize::Ceil(coverage->GetSize());
  fml::StatusOr<RenderTarget> render_target = renderer.MakeSubpass(
      label, subpass_size, command_buffer,
      [&contents = *this, &entity, &coverage](const ContentContext& renderer,
                                              RenderPass& pass) -> bool {
        Entity sub_entity;
        sub_entity.SetBlendMode(BlendMode::kSourceOver);
        sub_entity.SetTransform(
            Matrix::MakeTranslation(Vector3(-coverage->GetOrigin())) *
            entity.GetTransform());
        return contents.Render(renderer, sub_entity, pass);
      },
      msaa_enabled, /*depth_stencil_enabled=*/true,
      std::min(mip_count, static_cast<int32_t>(subpass_size.MipCount())));
 
  if (!render_target.ok()) {
    return std::nullopt;
  }
  if (!renderer.GetContext()
           ->GetCommandQueue()
           ->Submit(/*buffers=*/{std::move(command_buffer)})
           .ok()) {
    return std::nullopt;
  }
 
  auto snapshot = Snapshot{
      .texture = render_target.value().GetRenderTargetTexture(),
      .transform = Matrix::MakeTranslation(coverage->GetOrigin()),
  };
  if (sampler_descriptor.has_value()) {
    snapshot.sampler_descriptor = sampler_descriptor.value();
  }
 
  return snapshot;
}

SetColorSourceSize()

void impeller::Contents::SetColorSourceSize

(

Size

size

)

Definition at line 182 of file contents.cc.

                                           {
  color_source_size_ = size;
}

SetCoverageHint()

void impeller::Contents::SetCoverageHint

(

std::optional< Rect >

coverage_hint

)

Hint that specifies the coverage area of this Contents that will actually be used during rendering. This is for optimization purposes only and can not be relied on as a clip. May optionally affect the result of GetCoverage().

Definition at line 170 of file contents.cc.

                                                              {
  coverage_hint_ = coverage_hint;
}

SetInheritedOpacity()

void impeller::Contents::SetInheritedOpacity ( Scalar  opacity )

virtual

Inherit the provided opacity.

   Use of this method is invalid if CanAcceptOpacity returns false.

Reimplemented in impeller::ClipContents, impeller::ClipRestoreContents, impeller::ColorSourceContents, impeller::TextContents, and impeller::TextureContents.

Definition at line 136 of file contents.cc.

                                                 {
  VALIDATION_LOG << "Contents::SetInheritedOpacity should never be called when "
                    "Contents::CanAcceptOpacity returns false.";
}

ShouldRender()

bool impeller::Contents::ShouldRender ( const Entity &  entity, const std::optional< Rect >  clip_coverage  ) const

virtual

Reimplemented in impeller::ClipContents, and impeller::ClipRestoreContents.

Definition at line 155 of file contents.cc.

                                                                         {
  if (!clip_coverage.has_value()) {
    return false;
  }
  auto coverage = GetCoverage(entity);
  if (!coverage.has_value()) {
    return false;
  }
  if (coverage == Rect::MakeMaximum()) {
    return true;
  }
  return clip_coverage->IntersectsWithRect(coverage.value());
}

---

The documentation for this class was generated from the following files:

• impeller/entity/contents/contents.h
• impeller/entity/contents/contents.cc