impeller::TextureContents Class Reference

#include <texture_contents.h>

Inheritance diagram for impeller::TextureContents:

Public Member Functions
	TextureContents ()
	~TextureContents () override
void	SetLabel (std::string_view label)
void	SetDestinationRect (Rect rect)
void	SetTexture (std::shared_ptr< Texture > texture)
std::shared_ptr< Texture >	GetTexture () const
void	SetSamplerDescriptor (const SamplerDescriptor &desc)
const SamplerDescriptor &	GetSamplerDescriptor () const
void	SetSourceRect (const Rect &source_rect)
const Rect &	GetSourceRect () const
void	SetStrictSourceRect (bool strict)
bool	GetStrictSourceRect () const
void	SetOpacity (Scalar opacity)
Scalar	GetOpacity () const
void	SetStencilEnabled (bool enabled)
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. More...
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, std::string_view label="Texture 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). More...
bool	Render (const ContentContext &renderer, const Entity &entity, RenderPass &pass) const override
void	SetInheritedOpacity (Scalar opacity) override
	Inherit the provided opacity. More...
void	SetDeferApplyingOpacity (bool defer_applying_opacity)
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(). More...
const std::optional< Rect > &	GetCoverageHint () const
virtual bool	IsOpaque (const Matrix &transform) 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. More...
std::optional< Size >	GetColorSourceSize () const
	Return the color source's intrinsic size, if available. More...
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. More...
virtual bool	ApplyColorFilter (const ColorFilterProc &color_filter_proc)
	If possible, applies a color filter to this contents inputs on the CPU. More...

Static Public Member Functions
static std::shared_ptr< TextureContents >	MakeRect (Rect destination)
Static Public Member Functions inherited from impeller::Contents
static std::shared_ptr< Contents >	MakeAnonymous (RenderProc render_proc, CoverageProc coverage_proc)

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)>

Detailed Description

Represents the contents of a texture to be rendered.

This class encapsulates a texture along with parameters defining how it should be drawn, such as the source rectangle within the texture, the destination rectangle on the render target, opacity, and sampler settings. It's used by the rendering system to draw textured quads.

See also

TiledTextureContents for a tiled version.

Definition at line 25 of file texture_contents.h.

Constructor & Destructor Documentation

TextureContents()

impeller::TextureContents::TextureContents ( )

default

~TextureContents()

impeller::TextureContents::~TextureContents ( )

overridedefault

Member Function Documentation

GetCoverage()

std::optional< Rect > impeller::TextureContents::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 66 of file texture_contents.cc.

                                                                         {
  if (GetOpacity() == 0) {
    return std::nullopt;
  }
  return destination_rect_.TransformBounds(entity.GetTransform());
};

References GetOpacity(), impeller::Entity::GetTransform(), and impeller::TRect< T >::TransformBounds().

GetOpacity()

Scalar impeller::TextureContents::GetOpacity

(

)

const

Definition at line 62 of file texture_contents.cc.

                                         {
  return opacity_ * inherited_opacity_;
}

Referenced by GetCoverage(), Render(), and RenderToSnapshot().

GetSamplerDescriptor()

const SamplerDescriptor & impeller::TextureContents::GetSamplerDescriptor

(

)

const

Definition at line 251 of file texture_contents.cc.

                                                                     {
  return sampler_descriptor_;
}

GetSourceRect()

const Rect & impeller::TextureContents::GetSourceRect

(

)

const

Definition at line 235 of file texture_contents.cc.

                                                 {
  return source_rect_;
}

GetStrictSourceRect()

bool impeller::TextureContents::GetStrictSourceRect

(

)

const

Definition at line 243 of file texture_contents.cc.

                                                {
  return strict_source_rect_enabled_;
}

GetTexture()

std::shared_ptr< Texture > impeller::TextureContents::GetTexture

(

)

const

Definition at line 46 of file texture_contents.cc.

                                                         {
  return texture_;
}

MakeRect()

std::shared_ptr< TextureContents > impeller::TextureContents::MakeRect ( Rect  destination )

static

A common case factory that marks the texture contents as having a destination rectangle.

In this situation, a subpass can be avoided when image filters are applied.

Parameters

destination

The destination rectangle in the Entity's local coordinate space.

Definition at line 28 of file texture_contents.cc.

                                                                         {
  auto contents = std::make_shared<TextureContents>();
  contents->destination_rect_ = destination;
  return contents;
}

Referenced by impeller::Canvas::DrawImageRect(), impeller::Entity::FromSnapshot(), impeller::Canvas::SaveLayer(), and impeller::testing::TEST_P().

Render()

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

overridevirtual

Implements impeller::Contents.

Definition at line 106 of file texture_contents.cc.

                                                     {
  using VS = TextureFillVertexShader;
  using FS = TextureFillFragmentShader;
  using FSStrict = TextureFillStrictSrcFragmentShader;
 
  if (destination_rect_.IsEmpty() || source_rect_.IsEmpty() ||
      texture_ == nullptr || texture_->GetSize().IsEmpty()) {
    return true;  // Nothing to render.
  }
 
#ifdef IMPELLER_ENABLE_OPENGLES
  using FSExternal = TiledTextureFillExternalFragmentShader;
  bool is_external_texture =
      texture_->GetTextureDescriptor().type == TextureType::kTextureExternalOES;
#endif  // IMPELLER_ENABLE_OPENGLES
 
  auto texture_coords =
      Rect::MakeSize(texture_->GetSize()).Project(source_rect_);
  auto& host_buffer = renderer.GetTransientsBuffer();
 
  std::array<VS::PerVertexData, 4> vertices = {
      VS::PerVertexData{destination_rect_.GetLeftTop(),
                        texture_coords.GetLeftTop()},
      VS::PerVertexData{destination_rect_.GetRightTop(),
                        texture_coords.GetRightTop()},
      VS::PerVertexData{destination_rect_.GetLeftBottom(),
                        texture_coords.GetLeftBottom()},
      VS::PerVertexData{destination_rect_.GetRightBottom(),
                        texture_coords.GetRightBottom()},
  };
  auto vertex_buffer = CreateVertexBuffer(vertices, host_buffer);
 
  VS::FrameInfo frame_info;
  frame_info.mvp = entity.GetShaderTransform(pass);
  frame_info.texture_sampler_y_coord_scale = texture_->GetYCoordScale();
 
#ifdef IMPELLER_DEBUG
  if (label_.empty()) {
    pass.SetCommandLabel("Texture Fill");
  } else {
    pass.SetCommandLabel("Texture Fill: " + label_);
  }
#endif  // IMPELLER_DEBUG
 
  auto pipeline_options = OptionsFromPassAndEntity(pass, entity);
  if (!stencil_enabled_) {
    pipeline_options.stencil_mode = ContentContextOptions::StencilMode::kIgnore;
  }
  pipeline_options.primitive_type = PrimitiveType::kTriangleStrip;
 
  pipeline_options.depth_write_enabled =
      stencil_enabled_ && pipeline_options.blend_mode == BlendMode::kSrc;
 
#ifdef IMPELLER_ENABLE_OPENGLES
  if (is_external_texture) {
    pass.SetPipeline(
        renderer.GetTiledTextureExternalPipeline(pipeline_options));
  } else {
    pass.SetPipeline(
        strict_source_rect_enabled_
            ? renderer.GetTextureStrictSrcPipeline(pipeline_options)
            : renderer.GetTexturePipeline(pipeline_options));
  }
#else
  pass.SetPipeline(strict_source_rect_enabled_
                       ? renderer.GetTextureStrictSrcPipeline(pipeline_options)
                       : renderer.GetTexturePipeline(pipeline_options));
#endif  // IMPELLER_ENABLE_OPENGLES
 
  pass.SetVertexBuffer(vertex_buffer);
  VS::BindFrameInfo(pass, host_buffer.EmplaceUniform(frame_info));
 
  if (strict_source_rect_enabled_) {
    // For a strict source rect, shrink the texture coordinate range by half a
    // texel to ensure that linear filtering does not sample anything outside
    // the source rect bounds.
    auto strict_texture_coords =
        Rect::MakeSize(texture_->GetSize()).Project(source_rect_.Expand(-0.5));
 
    FSStrict::FragInfo frag_info;
    frag_info.source_rect = Vector4(strict_texture_coords.GetLTRB());
    frag_info.alpha = GetOpacity();
    FSStrict::BindFragInfo(pass, host_buffer.EmplaceUniform((frag_info)));
    FSStrict::BindTextureSampler(
        pass, texture_,
        renderer.GetContext()->GetSamplerLibrary()->GetSampler(
            sampler_descriptor_));
#ifdef IMPELLER_ENABLE_OPENGLES
  } else if (is_external_texture) {
    FSExternal::FragInfo frag_info;
    frag_info.x_tile_mode =
        static_cast<Scalar>(sampler_descriptor_.width_address_mode);
    frag_info.y_tile_mode =
        static_cast<Scalar>(sampler_descriptor_.height_address_mode);
    frag_info.alpha = GetOpacity();
    FSExternal::BindFragInfo(pass, host_buffer.EmplaceUniform(frag_info));
 
    SamplerDescriptor sampler_desc;
    // OES_EGL_image_external states that only CLAMP_TO_EDGE is valid, so
    // we emulate all other tile modes here by remapping the texture
    // coordinates.
    sampler_desc.width_address_mode = SamplerAddressMode::kClampToEdge;
    sampler_desc.height_address_mode = SamplerAddressMode::kClampToEdge;
    sampler_desc.min_filter = sampler_descriptor_.min_filter;
    sampler_desc.mag_filter = sampler_descriptor_.mag_filter;
    sampler_desc.mip_filter = MipFilter::kBase;
 
    FSExternal::BindSAMPLEREXTERNALOESTextureSampler(
        pass, texture_,
        renderer.GetContext()->GetSamplerLibrary()->GetSampler(sampler_desc));
#endif  //  IMPELLER_ENABLE_OPENGLES
  } else {
    FS::FragInfo frag_info;
    frag_info.alpha = GetOpacity();
    FS::BindFragInfo(pass, host_buffer.EmplaceUniform((frag_info)));
    FS::BindTextureSampler(
        pass, texture_,
        renderer.GetContext()->GetSamplerLibrary()->GetSampler(
            sampler_descriptor_));
  }
  return pass.Draw().ok();
}

References impeller::CreateVertexBuffer(), impeller::RenderPass::Draw(), impeller::TRect< T >::Expand(), impeller::ContentContext::GetContext(), impeller::TRect< T >::GetLeftBottom(), impeller::TRect< T >::GetLeftTop(), GetOpacity(), impeller::TRect< T >::GetRightBottom(), impeller::TRect< T >::GetRightTop(), impeller::Entity::GetShaderTransform(), impeller::ContentContext::GetTexturePipeline(), impeller::ContentContext::GetTextureStrictSrcPipeline(), impeller::ContentContext::GetTransientsBuffer(), impeller::SamplerDescriptor::height_address_mode, impeller::TRect< T >::IsEmpty(), impeller::kBase, impeller::kClampToEdge, impeller::ContentContextOptions::kIgnore, impeller::kSrc, impeller::kTextureExternalOES, impeller::kTriangleStrip, impeller::SamplerDescriptor::mag_filter, impeller::TRect< Scalar >::MakeSize(), impeller::SamplerDescriptor::min_filter, impeller::SamplerDescriptor::mip_filter, impeller::OptionsFromPassAndEntity(), impeller::TRect< T >::Project(), impeller::RenderPass::SetCommandLabel(), impeller::RenderPass::SetPipeline(), impeller::RenderPass::SetVertexBuffer(), and impeller::SamplerDescriptor::width_address_mode.

RenderToSnapshot()

std::optional< Snapshot > impeller::TextureContents::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, std::string_view  label = "Texture 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 73 of file texture_contents.cc.

                                {
  // Passthrough textures that have simple rectangle paths and complete source
  // rects.
  auto bounds = destination_rect_;
  auto opacity = GetOpacity();
  if (source_rect_ == Rect::MakeSize(texture_->GetSize()) &&
      (opacity >= 1 - kEhCloseEnough || defer_applying_opacity_)) {
    auto scale = Vector2(bounds.GetSize() / Size(texture_->GetSize()));
    return Snapshot{
        .texture = texture_,
        .transform = entity.GetTransform() *
                     Matrix::MakeTranslation(bounds.GetOrigin()) *
                     Matrix::MakeScale(scale),
        .sampler_descriptor = sampler_descriptor.value_or(sampler_descriptor_),
        .opacity = opacity};
  }
  return Contents::RenderToSnapshot(
      renderer,                                          // renderer
      entity,                                            // entity
      std::nullopt,                                      // coverage_limit
      sampler_descriptor.value_or(sampler_descriptor_),  // sampler_descriptor
      true,                                              // msaa_enabled
      /*mip_count=*/mip_count,
      label);  // label
}

References GetOpacity(), impeller::Entity::GetTransform(), impeller::kEhCloseEnough, impeller::Matrix::MakeScale(), impeller::TRect< Scalar >::MakeSize(), impeller::Matrix::MakeTranslation(), impeller::Contents::RenderToSnapshot(), and impeller::Snapshot::texture.

SetDeferApplyingOpacity()

void impeller::TextureContents::SetDeferApplyingOpacity

(

bool

defer_applying_opacity

)

Sets whether applying the opacity should be deferred.

When true, the opacity value (GetOpacity()) might not be applied directly during rendering operations like RenderToSnapshot. Instead, the opacity might be stored in the resulting Snapshot to be applied later when the snapshot is drawn. This is typically used as an optimization when the texture covers its destination rectangle completely and has near-full opacity, allowing the original texture to be used directly in the snapshot.

Parameters

defer_applying_opacity

True to defer applying opacity, false to apply it during rendering.

Definition at line 255 of file texture_contents.cc.

                                                                         {
  defer_applying_opacity_ = defer_applying_opacity;
}

SetDestinationRect()

void impeller::TextureContents::SetDestinationRect

(

Rect

rect

)

Sets the destination rectangle within the current render target where the texture will be drawn.

The texture, potentially clipped by the source_rect_, will be mapped to this rectangle. The coordinates are in the local coordinate space of the Entity.

Parameters

rect	The destination rectangle in the Entity's local coordinate space.

Definition at line 38 of file texture_contents.cc.

                                                  {
  destination_rect_ = rect;
}

SetInheritedOpacity()

void impeller::TextureContents::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 58 of file texture_contents.cc.

                                                        {
  inherited_opacity_ = opacity;
}

SetLabel()

void impeller::TextureContents::SetLabel

(

std::string_view

label

)

Sets a debug label for this contents object.

This label is used for debugging purposes, for example, in graphics debuggers or logs.

Parameters

label

The debug label string.

Definition at line 34 of file texture_contents.cc.

                                                   {
  label_ = label;
}

SetOpacity()

void impeller::TextureContents::SetOpacity

(

Scalar

opacity

)

Definition at line 50 of file texture_contents.cc.

                                               {
  opacity_ = opacity;
}

SetSamplerDescriptor()

void impeller::TextureContents::SetSamplerDescriptor

(

const SamplerDescriptor &

desc

)

Definition at line 247 of file texture_contents.cc.

                                                                        {
  sampler_descriptor_ = desc;
}

SetSourceRect()

void impeller::TextureContents::SetSourceRect

(

const Rect &

source_rect

)

Sets the source rectangle within the texture to sample from.

This rectangle defines the portion of the texture that will be mapped to the destination_rect_. The coordinates are in the coordinate space of the texture (texels), with the top-left corner being (0, 0).

Parameters

source_rect

The rectangle defining the area of the texture to use.

Definition at line 231 of file texture_contents.cc.

                                                           {
  source_rect_ = source_rect;
}

SetStencilEnabled()

void impeller::TextureContents::SetStencilEnabled

(

bool

enabled

)

Definition at line 54 of file texture_contents.cc.

                                                    {
  stencil_enabled_ = enabled;
}

SetStrictSourceRect()

void impeller::TextureContents::SetStrictSourceRect

(

bool

strict

)

Sets whether strict source rect sampling should be used.

When enabled, the texture coordinates are adjusted slightly (typically by half a texel) to ensure that linear filtering does not sample pixels outside the specified source_rect_. This is useful for preventing edge artifacts when rendering sub-sections of a texture atlas.

Parameters

strict

True to enable strict source rect sampling, false otherwise.

Definition at line 239 of file texture_contents.cc.

                                                     {
  strict_source_rect_enabled_ = strict;
}

SetTexture()

void impeller::TextureContents::SetTexture

(

std::shared_ptr< Texture >

texture

)

Definition at line 42 of file texture_contents.cc.

                                                               {
  texture_ = std::move(texture);
}

---

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

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