impeller::ColorSourceContents Class Reference

#include <color_source_contents.h>

Inheritance diagram for impeller::ColorSourceContents:

Public Member Functions
	ColorSourceContents ()
	~ColorSourceContents () override
void	SetGeometry (std::shared_ptr< Geometry > geometry)
	Set the geometry that this contents will use to render.
const std::shared_ptr< Geometry > &	GetGeometry () const
	Get the geometry that this contents will use to render.
void	SetEffectTransform (Matrix matrix)
	Set the effect transform for this color source.
const Matrix &	GetInverseEffectTransform () const
	Set the inverted effect transform for this color source.
void	SetOpacityFactor (Scalar opacity)
	Set the opacity factor for this color source.
Scalar	GetOpacityFactor () const
	Get the opacity factor for this color source.
virtual bool	IsSolidColor () const
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.
bool	CanInheritOpacity (const Entity &entity) const override
	Whether or not this contents can accept the opacity peephole optimization.
void	SetInheritedOpacity (Scalar opacity) override
	Inherit the provided opacity.
Public Member Functions inherited from impeller::Contents
	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
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 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.

Protected Types
using	BindFragmentCallback = std::function< bool(RenderPass &pass)>
using	PipelineBuilderMethod = std::shared_ptr< Pipeline< PipelineDescriptor > >(impeller::ContentContext::*)(ContentContextOptions) const
using	PipelineBuilderCallback = std::function< std::shared_ptr< Pipeline< PipelineDescriptor > >(ContentContextOptions)>

Protected Member Functions
template<typename VertexShaderT >
bool	DrawGeometry (const ContentContext &renderer, const Entity &entity, RenderPass &pass, const PipelineBuilderCallback &pipeline_callback, typename VertexShaderT::FrameInfo frame_info, const BindFragmentCallback &bind_fragment_callback) const

Additional Inherited Members
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)>
Static Public Member Functions inherited from impeller::Contents
static std::shared_ptr< Contents >	MakeAnonymous (RenderProc render_proc, CoverageProc coverage_proc)

Detailed Description

Color sources are geometry-ignostic Contents capable of shading any area defined by an impeller::Geometry. Conceptually, impeller::ColorSourceContents implement a particular color shading behavior.

This separation of concerns between geometry and color source output allows Impeller to handle most possible draw combinations in a consistent way. For example: There are color sources for handling solid colors, gradients, textures, custom runtime effects, and even 3D scenes.

There are some special rendering exceptions that deviate from this pattern and cross geometry and color source concerns, such as text atlas and image atlas rendering. Special Contents exist for rendering these behaviors which don't implement ColorSourceContents.

See also

impeller::Geometry

Definition at line 36 of file color_source_contents.h.

Member Typedef Documentation

BindFragmentCallback

using impeller::ColorSourceContents::BindFragmentCallback = std::function<bool(RenderPass& pass)>

protected

Definition at line 108 of file color_source_contents.h.

PipelineBuilderCallback

using impeller::ColorSourceContents::PipelineBuilderCallback = std::function<std::shared_ptr<Pipeline<PipelineDescriptor> >( ContentContextOptions)>

protected

Definition at line 111 of file color_source_contents.h.

PipelineBuilderMethod

using impeller::ColorSourceContents::PipelineBuilderMethod = std::shared_ptr<Pipeline<PipelineDescriptor> > ( impeller::ContentContext::*)(ContentContextOptions) const

protected

Definition at line 109 of file color_source_contents.h.

Constructor & Destructor Documentation

ColorSourceContents()

impeller::ColorSourceContents::ColorSourceContents ( )

default

~ColorSourceContents()

impeller::ColorSourceContents::~ColorSourceContents ( )

overridedefault

Member Function Documentation

CanInheritOpacity()

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

overridevirtual

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 from impeller::Contents.

Reimplemented in impeller::RuntimeEffectContents.

Definition at line 49 of file color_source_contents.cc.

                                                                      {
  return true;
}

DrawGeometry()

template<typename VertexShaderT >

bool impeller::ColorSourceContents::DrawGeometry ( const ContentContext &  renderer, const Entity &  entity, RenderPass &  pass, const PipelineBuilderCallback &  pipeline_callback, typename VertexShaderT::FrameInfo  frame_info, const BindFragmentCallback &  bind_fragment_callback  ) const

inlineprotected

Stencil preparation draw.

Cover draw.

Definition at line 116 of file color_source_contents.h.

                                                                              {
    auto options = OptionsFromPassAndEntity(pass, entity);
 
    GeometryResult::Mode geometry_mode = GetGeometry()->GetResultMode();
    Geometry& geometry = *GetGeometry();
 
    const bool is_stencil_then_cover =
        geometry_mode == GeometryResult::Mode::kNonZero ||
        geometry_mode == GeometryResult::Mode::kEvenOdd;
    if (is_stencil_then_cover) {
      pass.SetStencilReference(0);
 
      /// Stencil preparation draw.
 
      GeometryResult stencil_geometry_result =
          GetGeometry()->GetPositionBuffer(renderer, entity, pass);
      if (stencil_geometry_result.vertex_buffer.vertex_count == 0u) {
        return true;
      }
      pass.SetVertexBuffer(std::move(stencil_geometry_result.vertex_buffer));
      options.primitive_type = stencil_geometry_result.type;
 
      options.blend_mode = BlendMode::kDestination;
      switch (stencil_geometry_result.mode) {
        case GeometryResult::Mode::kNonZero:
          pass.SetCommandLabel("Stencil preparation (NonZero)");
          options.stencil_mode =
              ContentContextOptions::StencilMode::kStencilNonZeroFill;
          break;
        case GeometryResult::Mode::kEvenOdd:
          pass.SetCommandLabel("Stencil preparation (EvenOdd)");
          options.stencil_mode =
              ContentContextOptions::StencilMode::kStencilEvenOddFill;
          break;
        default:
          FML_UNREACHABLE();
      }
      pass.SetPipeline(renderer.GetClipPipeline(options));
      ClipPipeline::VertexShader::FrameInfo clip_frame_info;
      clip_frame_info.depth = entity.GetShaderClipDepth();
      clip_frame_info.mvp = stencil_geometry_result.transform;
      ClipPipeline::VertexShader::BindFrameInfo(
          pass, renderer.GetTransientsBuffer().EmplaceUniform(clip_frame_info));
 
      if (!pass.Draw().ok()) {
        return false;
      }
 
      /// Cover draw.
 
      options.blend_mode = entity.GetBlendMode();
      options.stencil_mode = ContentContextOptions::StencilMode::kCoverCompare;
      std::optional<Rect> maybe_cover_area = GetGeometry()->GetCoverage({});
      if (!maybe_cover_area.has_value()) {
        return true;
      }
      geometry = RectGeometry(maybe_cover_area.value());
    }
 
    GeometryResult geometry_result =
        geometry.GetPositionBuffer(renderer, entity, pass);
    if (geometry_result.vertex_buffer.vertex_count == 0u) {
      return true;
    }
    pass.SetVertexBuffer(std::move(geometry_result.vertex_buffer));
    options.primitive_type = geometry_result.type;
 
    // Take the pre-populated vertex shader uniform struct and set managed
    // values.
    frame_info.mvp = geometry_result.transform;
 
    // If overdraw prevention is enabled (like when drawing stroke paths), we
    // increment the stencil buffer as we draw, preventing overlapping fragments
    // from drawing. Afterwards, we need to append another draw call to clean up
    // the stencil buffer (happens below in this method).
    if (geometry_result.mode == GeometryResult::Mode::kPreventOverdraw) {
      options.stencil_mode =
          ContentContextOptions::StencilMode::kOverdrawPreventionIncrement;
    }
    pass.SetStencilReference(0);
 
    VertexShaderT::BindFrameInfo(
        pass, renderer.GetTransientsBuffer().EmplaceUniform(frame_info));
 
    // The reason we need to have a callback mechanism here is that this routine
    // may insert draw calls before the main draw call below. For example, for
    // sufficiently complex paths we may opt to use stencil-then-cover to avoid
    // tessellation.
    if (!bind_fragment_callback(pass)) {
      return false;
    }
 
    pass.SetPipeline(pipeline_callback(options));
 
    if (!pass.Draw().ok()) {
      return false;
    }
 
    // If we performed overdraw prevention, a subsection of the clip heightmap
    // was incremented by 1 in order to self-clip. So simply append a clip
    // restore to clean it up.
    if (geometry_result.mode == GeometryResult::Mode::kPreventOverdraw) {
      auto restore = ClipRestoreContents();
      restore.SetRestoreCoverage(GetCoverage(entity));
      Entity restore_entity = entity.Clone();
      return restore.Render(renderer, restore_entity, pass);
    }
    return true;
  }

GetCoverage()

std::optional< Rect > impeller::ColorSourceContents::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.

Reimplemented in impeller::FramebufferBlendContents, and impeller::SolidColorContents.

Definition at line 44 of file color_source_contents.cc.

                                {
  return geometry_->GetCoverage(entity.GetTransform());
};

GetGeometry()

const std::shared_ptr< Geometry > & impeller::ColorSourceContents::GetGeometry

(

)

const

Get the geometry that this contents will use to render.

Definition at line 20 of file color_source_contents.cc.

                                                                      {
  return geometry_;
}

GetInverseEffectTransform()

const Matrix & impeller::ColorSourceContents::GetInverseEffectTransform

(

)

const

Set the inverted effect transform for this color source.

     When the effect transform is set via `SetEffectTransform`, the
     value is inverted upon storage. The reason for this is that most
     color sources internally use the inverted transform.

Returns

The inverse of the transform set by SetEffectTransform.

See also

SetEffectTransform

Definition at line 36 of file color_source_contents.cc.

                                                                   {
  return inverse_matrix_;
}

GetOpacityFactor()

Scalar impeller::ColorSourceContents::GetOpacityFactor

(

)

const

Get the opacity factor for this color source.

    This value is is factored into the output of the color source in
    addition to opacity information that may be supplied any other
    inputs.

Note

If set, the output of this method factors factors in the inherited opacity of this Contents.

See also

Contents::CanInheritOpacity

Definition at line 28 of file color_source_contents.cc.

                                                   {
  return opacity_ * inherited_opacity_;
}

IsSolidColor()

bool impeller::ColorSourceContents::IsSolidColor ( ) const

virtual

Reimplemented in impeller::SolidColorContents.

Definition at line 40 of file color_source_contents.cc.

                                             {
  return false;
}

SetEffectTransform()

void impeller::ColorSourceContents::SetEffectTransform

(

Matrix

matrix

)

Set the effect transform for this color source.

    The effect transform is a transform matrix that is applied to
    the shaded color output and does not impact geometry in any way.

    For example: With repeat tiling, any gradient or
    `TiledTextureContents` could be used with an effect transform to
    inexpensively draw an infinite scrolling background pattern.

Definition at line 32 of file color_source_contents.cc.

                                                          {
  inverse_matrix_ = matrix.Invert();
}

SetGeometry()

void impeller::ColorSourceContents::SetGeometry

(

std::shared_ptr< Geometry >

geometry

)

Set the geometry that this contents will use to render.

Definition at line 16 of file color_source_contents.cc.

                                                                      {
  geometry_ = std::move(geometry);
}

SetInheritedOpacity()

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

overridevirtual

Inherit the provided opacity.

   Use of this method is invalid if CanAcceptOpacity returns false.

Reimplemented from impeller::Contents.

Definition at line 53 of file color_source_contents.cc.

                                                            {
  inherited_opacity_ = opacity;
}

SetOpacityFactor()

void impeller::ColorSourceContents::SetOpacityFactor

(

Scalar

opacity

)

Set the opacity factor for this color source.

Definition at line 24 of file color_source_contents.cc.

                                                       {
  opacity_ = alpha;
}

---

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

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