impeller::FilterContents Class Reference

#include <filter_contents.h>

Inheritance diagram for impeller::FilterContents:

Public Types
enum class	BlurStyle { kNormal , kSolid , kOuter , kInner }
enum class	MorphType { kDilate , kErode }
Public Types inherited from impeller::Contents
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
	FilterContents ()
	~FilterContents () override
void	SetInputs (FilterInput::Vector inputs)
	The input texture sources for this filter. Each input's emitted texture is expected to have premultiplied alpha colors.
void	SetEffectTransform (const Matrix &effect_transform)
	Sets the transform which gets appended to the effect of this filter. Note that this is in addition to the entity's transform.
std::optional< Entity >	GetEntity (const ContentContext &renderer, const Entity &entity, const std::optional< Rect > &coverage_hint) const
	Create an Entity that renders this filter's output.
bool	Render (const ContentContext &renderer, const Entity &entity, RenderPass &pass) const override
std::optional< Rect >	GetCoverage (const Entity &entity) const override
	Get the area of the render pass that will be affected when this contents is rendered.
void	PopulateGlyphAtlas (const std::shared_ptr< LazyGlyphAtlas > &lazy_glyph_atlas, Scalar scale) override
	Add any text data to the specified lazy atlas. The scale parameter must be used again later when drawing the text.
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="Filter Snapshot") const override
	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).
const FilterContents *	AsFilter () const override
	Cast to a filter. Returns nullptr if this Contents is not a filter.
std::optional< Rect >	GetSourceCoverage (const Matrix &effect_transform, const Rect &output_limit) const
	Determines the coverage of source pixels that will be needed to produce results for the specified |output_limit| under the specified |effect_transform|. This is essentially a reverse of the |GetCoverage| method computing a source coverage from an intended |output_limit| coverage.
virtual Matrix	GetLocalTransform (const Matrix &parent_transform) const
Matrix	GetTransform (const Matrix &parent_transform) const
virtual bool	IsTranslationOnly () const
	Returns true if this filter graph doesn't perform any basis transforms to the filtered content. For example: Rotating, scaling, and skewing are all basis transforms, but translating is not.
bool	IsLeaf () const
	Returns true if this filter does not have any FilterInput children.
void	SetLeafInputs (const FilterInput::Vector &inputs)
	Replaces the set of all leaf FilterContents with a new set of FilterInputs.
virtual void	SetRenderingMode (Entity::RenderingMode rendering_mode)
	Marks this filter chain as applying in a subpass scenario.
Public Member Functions inherited from impeller::Contents
	Contents ()
virtual	~Contents ()
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 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 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< FilterContents >	MakeGaussianBlur (const FilterInput::Ref &input, Sigma sigma_x, Sigma sigma_y, Entity::TileMode tile_mode=Entity::TileMode::kDecal, BlurStyle mask_blur_style=BlurStyle::kNormal, const std::shared_ptr< Geometry > &mask_geometry=nullptr)
static std::shared_ptr< FilterContents >	MakeBorderMaskBlur (FilterInput::Ref input, Sigma sigma_x, Sigma sigma_y, BlurStyle blur_style=BlurStyle::kNormal)
static std::shared_ptr< FilterContents >	MakeDirectionalMorphology (FilterInput::Ref input, Radius radius, Vector2 direction, MorphType morph_type)
static std::shared_ptr< FilterContents >	MakeMorphology (FilterInput::Ref input, Radius radius_x, Radius radius_y, MorphType morph_type)
static std::shared_ptr< FilterContents >	MakeMatrixFilter (FilterInput::Ref input, const Matrix &matrix, const SamplerDescriptor &desc)
static std::shared_ptr< FilterContents >	MakeLocalMatrixFilter (FilterInput::Ref input, const Matrix &matrix)
static std::shared_ptr< FilterContents >	MakeYUVToRGBFilter (std::shared_ptr< Texture > y_texture, std::shared_ptr< Texture > uv_texture, YUVColorSpace yuv_color_space)
Static Public Member Functions inherited from impeller::Contents
static std::shared_ptr< Contents >	MakeAnonymous (RenderProc render_proc, CoverageProc coverage_proc)

Static Public Attributes
static const int32_t	kBlurFilterRequiredMipCount

Private Member Functions
virtual std::optional< Rect >	GetFilterCoverage (const FilterInput::Vector &inputs, const Entity &entity, const Matrix &effect_transform) const
	Internal utility method for |GetLocalCoverage| that computes the output coverage of this filter across the specified inputs, ignoring the coverage hint.
virtual std::optional< Rect >	GetFilterSourceCoverage (const Matrix &effect_transform, const Rect &output_limit) const =0
	Internal utility method for |GetSourceCoverage| that computes the inverse effect of this transform on the specified output coverage, ignoring the inputs which will be accommodated by the caller.
virtual std::optional< Entity >	RenderFilter (const FilterInput::Vector &inputs, const ContentContext &renderer, const Entity &entity, const Matrix &effect_transform, const Rect &coverage, const std::optional< Rect > &coverage_hint) const =0
	Converts zero or more filter inputs into a render instruction.

Detailed Description

Definition at line 22 of file filter_contents.h.

Member Enumeration Documentation

BlurStyle

enum class impeller::FilterContents::BlurStyle

strong

Enumerator
kNormal	Blurred inside and outside.
kSolid	Solid inside, blurred outside.
kOuter	Nothing inside, blurred outside.
kInner	Blurred inside, nothing outside.

Definition at line 26 of file filter_contents.h.

                       {
    /// Blurred inside and outside.
    kNormal,
    /// Solid inside, blurred outside.
    kSolid,
    /// Nothing inside, blurred outside.
    kOuter,
    /// Blurred inside, nothing outside.
    kInner,
  };

MorphType

enum class impeller::FilterContents::MorphType

strong

Enumerator
kDilate
kErode

Definition at line 37 of file filter_contents.h.

{ kDilate, kErode };

Constructor & Destructor Documentation

FilterContents()

impeller::FilterContents::FilterContents ( )

default

~FilterContents()

impeller::FilterContents::~FilterContents ( )

overridedefault

Member Function Documentation

AsFilter()

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

overridevirtual

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

Reimplemented from impeller::Contents.

Definition at line 268 of file filter_contents.cc.

                                                     {
  return this;
}

GetCoverage()

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

overridevirtual

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.

Implements impeller::Contents.

Definition at line 162 of file filter_contents.cc.

                                                                        {
  Entity entity_with_local_transform = entity.Clone();
  entity_with_local_transform.SetTransform(GetTransform(entity.GetTransform()));
 
  return GetLocalCoverage(entity_with_local_transform);
}

GetEntity()

std::optional< Entity > impeller::FilterContents::GetEntity	(	const ContentContext &	renderer,
		const Entity &	entity,
		const std::optional< Rect > &	coverage_hint
	)		const

Create an Entity that renders this filter's output.

Definition at line 226 of file filter_contents.cc.

                                                  {
  Entity entity_with_local_transform = entity.Clone();
  entity_with_local_transform.SetTransform(GetTransform(entity.GetTransform()));
 
  auto coverage = GetLocalCoverage(entity_with_local_transform);
  if (!coverage.has_value() || coverage->IsEmpty()) {
    return std::nullopt;
  }
 
  return RenderFilter(inputs_, renderer, entity_with_local_transform,
                      effect_transform_, coverage.value(), coverage_hint);
}

GetFilterCoverage()

std::optional< Rect > impeller::FilterContents::GetFilterCoverage ( const FilterInput::Vector &  inputs, const Entity &  entity, const Matrix &  effect_transform  ) const

privatevirtual

Internal utility method for |GetLocalCoverage| that computes the output coverage of this filter across the specified inputs, ignoring the coverage hint.

Reimplemented in impeller::BorderMaskBlurFilterContents, impeller::GaussianBlurFilterContents, impeller::MatrixFilterContents, and impeller::DirectionalMorphologyFilterContents.

Definition at line 177 of file filter_contents.cc.

                                          {
  // The default coverage of FilterContents is just the union of its inputs'
  // coverage. FilterContents implementations may choose to adjust this
  // coverage depending on the use case.
 
  if (inputs_.empty()) {
    return std::nullopt;
  }
 
  std::optional<Rect> result;
  for (const auto& input : inputs) {
    auto coverage = input->GetCoverage(entity);
    if (!coverage.has_value()) {
      continue;
    }
    if (!result.has_value()) {
      result = coverage;
      continue;
    }
    result = result->Union(coverage.value());
  }
  return result;
}

GetFilterSourceCoverage()

virtual std::optional< Rect > impeller::FilterContents::GetFilterSourceCoverage ( const Matrix &  effect_transform, const Rect &  output_limit  ) const

privatepure virtual

Internal utility method for |GetSourceCoverage| that computes the inverse effect of this transform on the specified output coverage, ignoring the inputs which will be accommodated by the caller.

Implemented in impeller::BorderMaskBlurFilterContents, impeller::ColorFilterContents, impeller::GaussianBlurFilterContents, impeller::LocalMatrixFilterContents, impeller::MatrixFilterContents, impeller::DirectionalMorphologyFilterContents, and impeller::YUVToRGBFilterContents.

GetLocalTransform()

Matrix impeller::FilterContents::GetLocalTransform ( const Matrix &  parent_transform ) const

virtual

Reimplemented in impeller::LocalMatrixFilterContents.

Definition at line 272 of file filter_contents.cc.

                                                                             {
  return Matrix();
}

GetSourceCoverage()

std::optional< Rect > impeller::FilterContents::GetSourceCoverage	(	const Matrix &	effect_transform,
		const Rect &	output_limit
	)		const

Determines the coverage of source pixels that will be needed to produce results for the specified |output_limit| under the specified |effect_transform|. This is essentially a reverse of the |GetCoverage| method computing a source coverage from an intended |output_limit| coverage.

Both the |output_limit| and the return value are in the transformed coordinate space, and so do not need to be transformed or inverse transformed by the |effect_transform| but individual parameters on the filter might be in the untransformed space and should be transformed by the |effect_transform| before applying them to the coverages.

The method computes a result such that if the filter is applied to a set of pixels filling the computed source coverage, it should produce an output that covers the entire specified |output_limit|.

This is useful for subpass rendering scenarios where a filter will be applied to the output of the subpass and we need to determine how large of a render target to allocate in order to collect all pixels that might affect the supplied output coverage limit. While we might end up clipping the rendering of the subpass to its destination, we want to avoid clipping out any pixels that contribute to the output limit via the filtering operation.

Returns

The coverage bounds in the transformed space of any source pixel that may be needed to produce output for the indicated filter that covers the indicated |output_limit|.

Definition at line 204 of file filter_contents.cc.

                                    {
  auto filter_input_coverage =
      GetFilterSourceCoverage(effect_transform_, output_limit);
 
  if (!filter_input_coverage.has_value()) {
    return std::nullopt;
  }
 
  std::optional<Rect> inputs_coverage;
  for (const auto& input : inputs_) {
    auto input_coverage = input->GetSourceCoverage(
        effect_transform, filter_input_coverage.value());
    if (!input_coverage.has_value()) {
      return std::nullopt;
    }
    inputs_coverage = Rect::Union(inputs_coverage, input_coverage.value());
  }
  return inputs_coverage;
}

GetTransform()

Matrix impeller::FilterContents::GetTransform

(

const Matrix &

parent_transform

)

const

Definition at line 276 of file filter_contents.cc.

                                                                        {
  return parent_transform * GetLocalTransform(parent_transform);
}

IsLeaf()

bool impeller::FilterContents::IsLeaf

(

)

const

Returns true if this filter does not have any FilterInput children.

Definition at line 288 of file filter_contents.cc.

                                  {
  for (auto& input : inputs_) {
    if (!input->IsLeaf()) {
      return false;
    }
  }
  return true;
}

IsTranslationOnly()

bool impeller::FilterContents::IsTranslationOnly ( ) const

virtual

Returns true if this filter graph doesn't perform any basis transforms to the filtered content. For example: Rotating, scaling, and skewing are all basis transforms, but translating is not.

This is useful for determining whether a filtered object's space is compatible enough with the parent pass space to perform certain subpass clipping optimizations.

Reimplemented in impeller::MatrixFilterContents.

Definition at line 279 of file filter_contents.cc.

                                             {
  for (auto& input : inputs_) {
    if (!input->IsTranslationOnly()) {
      return false;
    }
  }
  return true;
}

MakeBorderMaskBlur()

std::shared_ptr< FilterContents > impeller::FilterContents::MakeBorderMaskBlur ( FilterInput::Ref  input, Sigma  sigma_x, Sigma  sigma_y, BlurStyle  blur_style = BlurStyle::kNormal  )

static

Definition at line 49 of file filter_contents.cc.

                          {
  auto filter = std::make_shared<BorderMaskBlurFilterContents>();
  filter->SetInputs({std::move(input)});
  filter->SetSigma(sigma_x, sigma_y);
  filter->SetBlurStyle(blur_style);
  return filter;
}

MakeDirectionalMorphology()

std::shared_ptr< FilterContents > impeller::FilterContents::MakeDirectionalMorphology ( FilterInput::Ref  input, Radius  radius, Vector2  direction, MorphType  morph_type  )

static

Definition at line 61 of file filter_contents.cc.

                          {
  auto filter = std::make_shared<DirectionalMorphologyFilterContents>();
  filter->SetInputs({std::move(input)});
  filter->SetRadius(radius);
  filter->SetDirection(direction);
  filter->SetMorphType(morph_type);
  return filter;
}

MakeGaussianBlur()

std::shared_ptr< FilterContents > impeller::FilterContents::MakeGaussianBlur ( const FilterInput::Ref &  input, Sigma  sigma_x, Sigma  sigma_y, Entity::TileMode  tile_mode = Entity::TileMode::kDecal, FilterContents::BlurStyle  mask_blur_style = BlurStyle::kNormal, const std::shared_ptr< Geometry > &  mask_geometry = nullptr  )

static

Creates a gaussian blur that operates in 2 dimensions. See also: MakeDirectionalGaussianBlur

Definition at line 36 of file filter_contents.cc.

                                                  {
  auto blur = std::make_shared<GaussianBlurFilterContents>(
      sigma_x.sigma, sigma_y.sigma, tile_mode, mask_blur_style, mask_geometry);
  blur->SetInputs({input});
  return blur;
}

MakeLocalMatrixFilter()

std::shared_ptr< FilterContents > impeller::FilterContents::MakeLocalMatrixFilter ( FilterInput::Ref  input, const Matrix &  matrix  )

static

Definition at line 97 of file filter_contents.cc.

                          {
  auto filter = std::make_shared<LocalMatrixFilterContents>();
  filter->SetInputs({std::move(input)});
  filter->SetMatrix(matrix);
  return filter;
}

MakeMatrixFilter()

std::shared_ptr< FilterContents > impeller::FilterContents::MakeMatrixFilter ( FilterInput::Ref  input, const Matrix &  matrix, const SamplerDescriptor &  desc  )

static

Definition at line 86 of file filter_contents.cc.

                                   {
  auto filter = std::make_shared<MatrixFilterContents>();
  filter->SetInputs({std::move(input)});
  filter->SetMatrix(matrix);
  filter->SetSamplerDescriptor(desc);
  return filter;
}

MakeMorphology()

std::shared_ptr< FilterContents > impeller::FilterContents::MakeMorphology ( FilterInput::Ref  input, Radius  radius_x, Radius  radius_y, MorphType  morph_type  )

static

Definition at line 74 of file filter_contents.cc.

                          {
  auto x_morphology = MakeDirectionalMorphology(std::move(input), radius_x,
                                                Point(1, 0), morph_type);
  auto y_morphology = MakeDirectionalMorphology(
      FilterInput::Make(x_morphology), radius_y, Point(0, 1), morph_type);
  return y_morphology;
}

MakeYUVToRGBFilter()

std::shared_ptr< FilterContents > impeller::FilterContents::MakeYUVToRGBFilter ( std::shared_ptr< Texture >  y_texture, std::shared_ptr< Texture >  uv_texture, YUVColorSpace  yuv_color_space  )

static

Definition at line 106 of file filter_contents.cc.

                                   {
  auto filter = std::make_shared<impeller::YUVToRGBFilterContents>();
  filter->SetInputs({impeller::FilterInput::Make(y_texture),
                     impeller::FilterInput::Make(uv_texture)});
  filter->SetYUVColorSpace(yuv_color_space);
  return filter;
}

PopulateGlyphAtlas()

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

overridevirtual

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

Reimplemented from impeller::Contents.

Definition at line 169 of file filter_contents.cc.

                  {
  for (auto& input : inputs_) {
    input->PopulateGlyphAtlas(lazy_glyph_atlas, scale);
  }
}

Render()

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

overridevirtual

Implements impeller::Contents.

Definition at line 133 of file filter_contents.cc.

                                                    {
  auto filter_coverage = GetCoverage(entity);
  if (!filter_coverage.has_value()) {
    return true;
  }
 
  // Run the filter.
 
  auto maybe_entity = GetEntity(renderer, entity, GetCoverageHint());
  if (!maybe_entity.has_value()) {
    return true;
  }
  maybe_entity->SetClipDepth(entity.GetClipDepth());
  return maybe_entity->Render(renderer, pass);
}

RenderFilter()

virtual std::optional< Entity > impeller::FilterContents::RenderFilter ( const FilterInput::Vector &  inputs, const ContentContext &  renderer, const Entity &  entity, const Matrix &  effect_transform, const Rect &  coverage, const std::optional< Rect > &  coverage_hint  ) const

privatepure virtual

Converts zero or more filter inputs into a render instruction.

Implemented in impeller::BorderMaskBlurFilterContents, impeller::ColorMatrixFilterContents, impeller::GaussianBlurFilterContents, impeller::LinearToSrgbFilterContents, impeller::LocalMatrixFilterContents, impeller::MatrixFilterContents, impeller::DirectionalMorphologyFilterContents, impeller::SrgbToLinearFilterContents, impeller::YUVToRGBFilterContents, and impeller::BlendFilterContents.

RenderToSnapshot()

std::optional< Snapshot > impeller::FilterContents::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 = "Filter Snapshot"  ) const

overridevirtual

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 from impeller::Contents.

Definition at line 242 of file filter_contents.cc.

                                  {
  // Resolve the render instruction (entity) from the filter and render it to a
  // snapshot.
  if (std::optional<Entity> result =
          GetEntity(renderer, entity, coverage_limit);
      result.has_value()) {
    return result->GetContents()->RenderToSnapshot(
        renderer,        // renderer
        result.value(),  // entity
        coverage_limit,  // coverage_limit
        std::nullopt,    // sampler_descriptor
        true,            // msaa_enabled
        /*mip_count=*/mip_count,
        label);  // label
  }
 
  return std::nullopt;
}

SetEffectTransform()

void impeller::FilterContents::SetEffectTransform

(

const Matrix &

effect_transform

)

Sets the transform which gets appended to the effect of this filter. Note that this is in addition to the entity's transform.

This is useful for subpass rendering scenarios where it's difficult to encode the current transform of the layer into the Entity being rendered.

Definition at line 125 of file filter_contents.cc.

                                                                      {
  effect_transform_ = effect_transform;
 
  for (auto& input : inputs_) {
    input->SetEffectTransform(effect_transform);
  }
}

SetInputs()

void impeller::FilterContents::SetInputs

(

FilterInput::Vector

inputs

)

The input texture sources for this filter. Each input's emitted texture is expected to have premultiplied alpha colors.

The number of required or optional textures depends on the particular filter's implementation.

Definition at line 121 of file filter_contents.cc.

                                                       {
  inputs_ = std::move(inputs);
}

SetLeafInputs()

void impeller::FilterContents::SetLeafInputs

(

const FilterInput::Vector &

inputs

)

Replaces the set of all leaf FilterContents with a new set of FilterInputs.

See also

FilterContents::IsLeaf

Definition at line 297 of file filter_contents.cc.

                                                                  {
  if (IsLeaf()) {
    inputs_ = inputs;
    return;
  }
  for (auto& input : inputs_) {
    input->SetLeafInputs(inputs);
  }
}

SetRenderingMode()

void impeller::FilterContents::SetRenderingMode ( Entity::RenderingMode  rendering_mode )

virtual

Marks this filter chain as applying in a subpass scenario.

    Subpasses render in screenspace, and this setting informs filters
    that the current transform matrix of the entity is not stored
    in the Entity transform matrix. Instead, the effect transform
    is used in this case. 

Reimplemented in impeller::MatrixFilterContents.

Definition at line 307 of file filter_contents.cc.

                                                                        {
  for (auto& input : inputs_) {
    input->SetRenderingMode(rendering_mode);
  }
}

Member Data Documentation

kBlurFilterRequiredMipCount

const int32_t impeller::FilterContents::kBlurFilterRequiredMipCount

static

Initial value:

=
    GaussianBlurFilterContents::kBlurFilterRequiredMipCount

Definition at line 24 of file filter_contents.h.

---

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

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