| Flutter Impeller |

Classes | Public Types | Public Member Functions | Static Public Member Functions | List of all members
impeller::Contents Class Referenceabstract

`#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. More...
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. More...
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
| 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...
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. More...
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, 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)`. More...
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. More...
void | SetColorSourceSize (Size size)
virtual bool | CanInheritOpacity (const Entity &entity) const
| Whether or not this contents can accept the opacity peephole optimization. More...
virtual void | SetInheritedOpacity (Scalar opacity)
| Inherit the provided opacity. More...
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 const FilterContents * | AsFilter () const
| Cast to a filter. Returns `nullptr` if this Contents is not a filter. 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< 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 49 of file contents.h.

## Constructor & Destructor Documentation

## ◆ Contents()

impeller::Contents::Contents | ( |  | ) |
| default

## ◆ ~Contents()

impeller::Contents::~Contents | ( |  | ) |
| virtual default

## 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::SolidColorContents, impeller::SolidRRectBlurContents, impeller::LinearGradientContents, impeller::SweepGradientContents, impeller::RadialGradientContents, and impeller::ConicalGradientContents.

Definition at line 128 of file contents.cc.

129 {
130 return false;
131 }

## ◆ 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 119 of file contents.cc.

120 {
121 return {};
122 }

## ◆ 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 124 of file contents.cc.

124 {
125 return nullptr;
126 }

## ◆ 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::ColorSourceContents, impeller::ClipRestoreContents, impeller::TextureContents, impeller::ClipContents, impeller::TextContents, and impeller::RuntimeEffectContents.

Definition at line 110 of file contents.cc.

110 {
111 return false;
112 }

## ◆ 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::ClipRestoreContents, and impeller::ClipContents.

Definition at line 50 of file contents.cc.

52 {
53 return {.type = ClipCoverage::Type::kNoChange,
54 .coverage = current_clip_coverage};
55 }

References impeller::Contents::ClipCoverage::kNoChange, and impeller::Contents::ClipCoverage::type.

## ◆ 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 156 of file contents.cc.

156 {
157 return color_source_size_;
158 };

## ◆ 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::AtlasColorContents, impeller::FilterContents, impeller::AtlasTextureContents, impeller::ColorSourceContents, impeller::VerticesUVContents, impeller::ClipRestoreContents, impeller::AtlasContents, impeller::VerticesColorContents, impeller::TextureContents, impeller::TextContents, impeller::SolidColorContents, impeller::VerticesContents, impeller::SolidRRectBlurContents, impeller::AnonymousContents, impeller::ClipContents, and impeller::CheckerboardContents.

Referenced by RenderToSnapshot(), and ShouldRender().

## ◆ GetCoverageHint()

const std::optional< Rect > & impeller::Contents::GetCoverageHint | ( |  | ) | const

Definition at line 152 of file contents.cc.

152 {
153 return coverage_hint_;
154 }

Referenced by impeller::VerticesContents::Render(), impeller::VerticesUVContents::Render(), and impeller::FilterContents::Render().

## ◆ 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::SolidColorContents, impeller::TiledTextureContents, impeller::LinearGradientContents, impeller::SweepGradientContents, and impeller::RadialGradientContents.

Definition at line 46 of file contents.cc.

46 {
47 return false;
48 }

Referenced by impeller::testing::TEST_P().

## ◆ MakeAnonymous()

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

Definition at line 35 of file contents.cc.

37 {
38 return AnonymousContents::Make(std::move(render_proc),
39 std::move(coverage_proc));
40 }

References impeller::AnonymousContents::Make().

## ◆ PopulateGlyphAtlas()

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

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.

63 {}

## ◆ Render()

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

Implemented in impeller::AtlasColorContents, impeller::FilterContents, impeller::AtlasTextureContents, impeller::VerticesUVContents, impeller::ClipRestoreContents, impeller::AtlasContents, impeller::VerticesColorContents, impeller::TextureContents, impeller::TextContents, impeller::SolidColorContents, impeller::VerticesContents, impeller::SolidRRectBlurContents, impeller::ClipContents, impeller::TiledTextureContents, impeller::RuntimeEffectContents, impeller::LinearGradientContents, impeller::SceneContents, impeller::SweepGradientContents, impeller::RadialGradientContents, impeller::ConicalGradientContents, impeller::AnonymousContents, and impeller::CheckerboardContents.

## ◆ 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`,
|  | 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::TiledTextureContents, impeller::TextureContents, and impeller::FilterContents.

Definition at line 57 of file contents.cc.

63 {
64 auto coverage = GetCoverage(entity);
65 if (!coverage.has_value()) {
66 return std::nullopt;
67 }
68
69 // Pad Contents snapshots with 1 pixel borders to ensure correct sampling
70 // behavior. Not doing so results in a coverage leak for filters that support
71 // customizing the input sampling mode. Snapshots of contents should be
72 // theoretically treated as infinite size just like layers.
73 coverage = coverage->Expand(1);
74
75 if (coverage_limit.has_value()) {
76 coverage = coverage->Intersection(*coverage_limit);
77 if (!coverage.has_value()) {
78 return std::nullopt;
79 }
80 }
81
82 fml::StatusOr<RenderTarget> render_target = renderer.MakeSubpass(
83 label, ISize::Ceil(coverage->GetSize()),
84 [&contents = *this, &entity, &coverage](const ContentContext& renderer,
85 RenderPass& pass) -> bool {
86 Entity sub_entity;
87 sub_entity.SetBlendMode(BlendMode::kSourceOver);
88 sub_entity.SetTransform(
89 Matrix::MakeTranslation(Vector3(-coverage->GetOrigin())) *
90 entity.GetTransform());
91 return contents.Render(renderer, sub_entity, pass);
92 },
93 msaa_enabled);
94
95 if (!render_target.ok()) {
96 return std::nullopt;
97 }
98
99 auto snapshot = Snapshot{
100 .texture = render_target.value().GetRenderTargetTexture(),
101 .transform = Matrix::MakeTranslation(coverage->GetOrigin()),
102 };
103 if (sampler_descriptor.has_value()) {
104 snapshot.sampler_descriptor = sampler_descriptor.value();
105 }
106
107 return snapshot;
108 }

References impeller::TSize< int64_t >::Ceil(), GetCoverage(), impeller::ContentContext::MakeSubpass(), impeller::Matrix::MakeTranslation(), and impeller::Snapshot::texture.

Referenced by impeller::TextureContents::RenderToSnapshot(), and impeller::TiledTextureContents::RenderToSnapshot().

## ◆ SetColorSourceSize()

void impeller::Contents::SetColorSourceSize | ( | Size | size | ) |

Definition at line 160 of file contents.cc.

160 {
161 color_source_size_ = size;
162 }

## ◆ 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 148 of file contents.cc.

148 {
149 coverage_hint_ = coverage_hint;
150 }

## ◆ 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::ColorSourceContents, impeller::ClipRestoreContents, impeller::TextureContents, impeller::ClipContents, and impeller::TextContents.

Definition at line 114 of file contents.cc.

114 {
115 VALIDATION_LOG << "Contents::SetInheritedOpacity should never be called when "
116 "Contents::CanAcceptOpacity returns false.";
117 }

References VALIDATION_LOG.

## ◆ ShouldRender()

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

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

Definition at line 133 of file contents.cc.

134 {
135 if (!clip_coverage.has_value()) {
136 return false;
137 }
138 auto coverage = GetCoverage(entity);
139 if (!coverage.has_value()) {
140 return false;
141 }
142 if (coverage == Rect::MakeMaximum()) {
143 return true;
144 }
145 return clip_coverage->IntersectsWithRect(coverage.value());
146 }

References GetCoverage(), and impeller::TRect< Scalar >::MakeMaximum().

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

- impeller/entity/contents/contents.h
- impeller/entity/contents/contents.cc

impeller::Contents::GetCoverage
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.
impeller::TSize< int64_t >::Ceil
constexpr TSize Ceil() const
Definition: size.h:96
impeller::Matrix::MakeTranslation
static constexpr Matrix MakeTranslation(const Vector3 &t)
Definition: matrix.h:95
VALIDATION_LOG
#define VALIDATION_LOG
Definition: validation.h:67
impeller::TRect< Scalar >::MakeMaximum
constexpr static TRect MakeMaximum()
Definition: rect.h:72
impeller::Contents::ClipCoverage::Type::kNoChange
@ kNoChange
impeller::AnonymousContents::Make
static std::shared_ptr< Contents > Make(RenderProc render_proc, CoverageProc coverage_proc)
Definition: anonymous_contents.cc:11