| Flutter Impeller |

Public Member Functions | Protected Types | Protected Member Functions | Static Protected Member Functions | List of all members
impeller::ColorSourceContents Class Reference

`#include <color_source_contents.h>`

Inheritance diagram for impeller::ColorSourceContents:

## Public Member Functions
| ColorSourceContents ()
| ~ColorSourceContents () override
void | SetGeometry (const Geometry *geometry)
| Set the geometry that this contents will use to render. More...
const Geometry * | GetGeometry () const
| Get the geometry that this contents will use to render. More...
void | SetEffectTransform (Matrix matrix)
| Set the effect transform for this color source. More...
const Matrix & | GetInverseEffectTransform () const
| Set the inverted effect transform for this color source. More...
void | SetOpacityFactor (Scalar opacity)
| Set the opacity factor for this color source. More...
Scalar | GetOpacityFactor () const
| Get the opacity factor for this color source. More...
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. More...
void | SetInheritedOpacity (Scalar opacity) override
| Inherit the provided opacity. More...
Public Member Functions inherited from impeller::Contents
| Contents ()
virtual | ~Contents ()
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()`. 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...
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, std::string_view 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...
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...

## Protected Types
using | BindFragmentCallback = std::function< bool(RenderPass &pass)>
using | PipelineBuilderCallback = std::function< PipelineRef(ContentContextOptions)>
using | CreateGeometryCallback = std::function< GeometryResult(const ContentContext &renderer, const Entity &entity, RenderPass &pass, const Geometry *geom)>

## Protected Member Functions
bool | AppliesAlphaForStrokeCoverage (const Matrix &transform) const
| Whether the entity should be treated as non-opaque due to stroke geometry requiring alpha for coverage. More...
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, bool force_stencil=false, const CreateGeometryCallback &create_geom_callback=DefaultCreateGeometryCallback) const

## Static Protected Member Functions
static GeometryResult | DefaultCreateGeometryCallback (const ContentContext &renderer, const Entity &entity, RenderPass &pass, const Geometry *geom)

## 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 37 of file color_source_contents.h.

## Member Typedef Documentation

## ◆ BindFragmentCallback

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

Definition at line 103 of file color_source_contents.h.

## ◆ CreateGeometryCallback

using impeller::ColorSourceContents::CreateGeometryCallback = std::function<GeometryResult(const ContentContext& renderer, const Entity& entity, RenderPass& pass, const Geometry* geom)>
| protected

Definition at line 110 of file color_source_contents.h.

## ◆ PipelineBuilderCallback

using impeller::ColorSourceContents::PipelineBuilderCallback = std::function<PipelineRef(ContentContextOptions)>
| protected

Definition at line 105 of file color_source_contents.h.

## Constructor & Destructor Documentation

## ◆ ColorSourceContents()

impeller::ColorSourceContents::ColorSourceContents | ( |  | ) |
| default

## ◆ ~ColorSourceContents()

impeller::ColorSourceContents::~ColorSourceContents | ( |  | ) |
| override default

## Member Function Documentation

## ◆ AppliesAlphaForStrokeCoverage()

bool impeller::ColorSourceContents::AppliesAlphaForStrokeCoverage | ( | const Matrix & | transform | ) | const
| protected

Whether the entity should be treated as non-opaque due to stroke geometry requiring alpha for coverage.

Definition at line 53 of file color_source_contents.cc.

54 {
55 return GetGeometry() && GetGeometry()->ComputeAlphaCoverage(transform) < 1.0;
56 }

References impeller::Geometry::ComputeAlphaCoverage(), GetGeometry(), and transform.

Referenced by impeller::LinearGradientContents::IsOpaque(), impeller::RadialGradientContents::IsOpaque(), impeller::SweepGradientContents::IsOpaque(), impeller::SolidColorContents::IsOpaque(), and impeller::TiledTextureContents::IsOpaque().

## ◆ DefaultCreateGeometryCallback()

static GeometryResult impeller::ColorSourceContents::DefaultCreateGeometryCallback | ( | const ContentContext & | renderer,
|  | const Entity & | entity,
|  | RenderPass & | pass,
|  | const Geometry * | geom
| ) |  |
| inline static protected

Definition at line 112 of file color_source_contents.h.

116 {
117 return geom->GetPositionBuffer(renderer, entity, pass);
118 }

References impeller::Geometry::GetPositionBuffer().

## ◆ 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,
|  | bool | force_stencil = `false`,
|  | const CreateGeometryCallback & | create_geom_callback = `DefaultCreateGeometryCallback`
| ) |  | const
| inline protected

Stencil preparation draw.

Cover draw.

Definition at line 125 of file color_source_contents.h.

133 {
134 auto options = OptionsFromPassAndEntity(pass, entity);
135
136 GeometryResult::Mode geometry_mode = GetGeometry()->GetResultMode();
137 bool do_cover_draw = false;
138 Rect cover_area = {};
139
140 bool is_stencil_then_cover =
141 geometry_mode == GeometryResult::Mode::kNonZero ||
142 geometry_mode == GeometryResult::Mode::kEvenOdd;
143 if (!is_stencil_then_cover && force_stencil) {
144 geometry_mode = GeometryResult::Mode::kNonZero;
145 is_stencil_then_cover = true;
146 }
147
148 if (is_stencil_then_cover) {
149 pass.SetStencilReference(0);
150
151 /// Stencil preparation draw.
152
153 GeometryResult stencil_geometry_result =
154 GetGeometry()->GetPositionBuffer(renderer, entity, pass);
155 if (stencil_geometry_result.vertex_buffer.vertex_count == 0u) {
156 return true;
157 }
158 pass.SetVertexBuffer(std::move(stencil_geometry_result.vertex_buffer));
159 options.primitive_type = stencil_geometry_result.type;
160
161 options.blend_mode = BlendMode::kDestination;
162 switch (stencil_geometry_result.mode) {
163 case GeometryResult::Mode::kNonZero:
164 pass.SetCommandLabel("Stencil preparation (NonZero)");
165 options.stencil_mode =
166 ContentContextOptions::StencilMode::kStencilNonZeroFill;
167 break;
168 case GeometryResult::Mode::kEvenOdd:
169 pass.SetCommandLabel("Stencil preparation (EvenOdd)");
170 options.stencil_mode =
171 ContentContextOptions::StencilMode::kStencilEvenOddFill;
172 break;
173 default:
174 if (force_stencil) {
175 pass.SetCommandLabel("Stencil preparation (NonZero)");
176 options.stencil_mode =
177 ContentContextOptions::StencilMode::kStencilNonZeroFill;
178 break;
179 }
180 FML_UNREACHABLE();
181 }
182 pass.SetPipeline(renderer.GetClipPipeline(options));
183 ClipPipeline::VertexShader::FrameInfo clip_frame_info;
184 clip_frame_info.depth = entity.GetShaderClipDepth();
185 clip_frame_info.mvp = stencil_geometry_result.transform;
186 ClipPipeline::VertexShader::BindFrameInfo(
187 pass, renderer.GetTransientsBuffer().EmplaceUniform(clip_frame_info));
188
189 if (!pass.Draw().ok()) {
190 return false;
191 }
192
193 /// Cover draw.
194
195 options.blend_mode = entity.GetBlendMode();
196 options.stencil_mode = ContentContextOptions::StencilMode::kCoverCompare;
197 std::optional<Rect> maybe_cover_area = GetGeometry()->GetCoverage({});
198 if (!maybe_cover_area.has_value()) {
199 return true;
200 }
201 do_cover_draw = true;
202 cover_area = maybe_cover_area.value();
203 }
204
205 GeometryResult geometry_result;
206 if (do_cover_draw) {
207 RectGeometry geom(cover_area);
208 geometry_result = create_geom_callback(renderer, entity, pass, &geom);
209 } else {
210 geometry_result =
211 create_geom_callback(renderer, entity, pass, GetGeometry());
212 }
213
214 if (geometry_result.vertex_buffer.vertex_count == 0u) {
215 return true;
216 }
217 pass.SetVertexBuffer(std::move(geometry_result.vertex_buffer));
218 options.primitive_type = geometry_result.type;
219
220 // Enable depth writing for all opaque entities in order to allow
221 // reordering. Opaque entities are coerced to source blending by
222 // `EntityPass::AddEntity`.
223 options.depth_write_enabled = options.blend_mode == BlendMode::kSource;
224
225 // Take the pre-populated vertex shader uniform struct and set managed
226 // values.
227 frame_info.mvp = geometry_result.transform;
228
229 // If overdraw prevention is enabled (like when drawing stroke paths), we
230 // increment the stencil buffer as we draw, preventing overlapping fragments
231 // from drawing. Afterwards, we need to append another draw call to clean up
232 // the stencil buffer (happens below in this method). This can be skipped
233 // for draws that are fully opaque or use src blend mode.
234 if (geometry_result.mode == GeometryResult::Mode::kPreventOverdraw &&
235 options.blend_mode != BlendMode::kSource) {
236 options.stencil_mode =
237 ContentContextOptions::StencilMode::kOverdrawPreventionIncrement;
238 }
239 pass.SetStencilReference(0);
240
241 VertexShaderT::BindFrameInfo(
242 pass, renderer.GetTransientsBuffer().EmplaceUniform(frame_info));
243
244 // The reason we need to have a callback mechanism here is that this routine
245 // may insert draw calls before the main draw call below. For example, for
246 // sufficiently complex paths we may opt to use stencil-then-cover to avoid
247 // tessellation.
248 if (!bind_fragment_callback(pass)) {
249 return false;
250 }
251
252 pass.SetPipeline(pipeline_callback(options));
253
254 if (!pass.Draw().ok()) {
255 return false;
256 }
257
258 // If we performed overdraw prevention, a subsection of the clip heightmap
259 // was incremented by 1 in order to self-clip. So simply append a clip
260 // restore to clean it up.
261 if (geometry_result.mode == GeometryResult::Mode::kPreventOverdraw &&
262 options.blend_mode != BlendMode::kSource) {
263 return RenderClipRestore(renderer, pass, entity.GetClipDepth(),
264 GetCoverage(entity));
265 }
266 return true;
267 }

References impeller::RenderPass::Draw(), impeller::HostBuffer::EmplaceUniform(), impeller::Entity::GetBlendMode(), impeller::Entity::GetClipDepth(), impeller::ContentContext::GetClipPipeline(), impeller::Geometry::GetCoverage(), GetCoverage(), GetGeometry(), impeller::Geometry::GetPositionBuffer(), impeller::Geometry::GetResultMode(), impeller::Entity::GetShaderClipDepth(), impeller::ContentContext::GetTransientsBuffer(), impeller::ContentContextOptions::kCoverCompare, impeller::kDestination, impeller::GeometryResult::kEvenOdd, impeller::GeometryResult::kNonZero, impeller::ContentContextOptions::kOverdrawPreventionIncrement, impeller::GeometryResult::kPreventOverdraw, impeller::kSource, impeller::ContentContextOptions::kStencilEvenOddFill, impeller::ContentContextOptions::kStencilNonZeroFill, impeller::GeometryResult::mode, impeller::OptionsFromPassAndEntity(), impeller::RenderClipRestore(), impeller::RenderPass::SetCommandLabel(), impeller::RenderPass::SetPipeline(), impeller::RenderPass::SetStencilReference(), impeller::RenderPass::SetVertexBuffer(), impeller::GeometryResult::transform, impeller::GeometryResult::type, impeller::GeometryResult::vertex_buffer, and impeller::VertexBuffer::vertex_count.

## ◆ GetCoverage()

std::optional< Rect > impeller::ColorSourceContents::GetCoverage | ( | const Entity & | entity | ) | const
| override 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.

Implements impeller::Contents.

Reimplemented in impeller::SolidColorContents.

Definition at line 44 of file color_source_contents.cc.

45 {
46 return geometry_->GetCoverage(entity.GetTransform());
47 };

References impeller::Geometry::GetCoverage(), and impeller::Entity::GetTransform().

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

## ◆ GetGeometry()

const 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.

20 {
21 return geometry_;
22 }

Referenced by AppliesAlphaForStrokeCoverage(), impeller::SolidColorContents::AsBackgroundColor(), DrawGeometry(), impeller::SolidColorContents::GetCoverage(), impeller::TiledTextureContents::Render(), impeller::SolidColorContents::Render(), and impeller::TiledTextureContents::RenderToSnapshot().

## ◆ 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.

36 {
37 return inverse_matrix_;
38 }

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

## ◆ 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`.

Definition at line 28 of file color_source_contents.cc.

28 {
29 return opacity_ * inherited_opacity_;
30 }

Referenced by impeller::SolidColorContents::GetColor(), impeller::RadialGradientContents::IsOpaque(), impeller::LinearGradientContents::IsOpaque(), impeller::SweepGradientContents::IsOpaque(), impeller::TiledTextureContents::IsOpaque(), impeller::TiledTextureContents::Render(), and impeller::TiledTextureContents::RenderToSnapshot().

## ◆ IsSolidColor()

bool impeller::ColorSourceContents::IsSolidColor | ( |  | ) | const
| virtual

Reimplemented in impeller::SolidColorContents.

Definition at line 40 of file color_source_contents.cc.

40 {
41 return false;
42 }

## ◆ 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.

32 {
33 inverse_matrix_ = matrix.Invert();
34 }

References impeller::Matrix::Invert().

## ◆ SetGeometry()

void impeller::ColorSourceContents::SetGeometry | ( | const Geometry * | geometry | ) |

Set the geometry that this contents will use to render.

Definition at line 16 of file color_source_contents.cc.

16 {
17 geometry_ = geometry;
18 }

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

## ◆ SetInheritedOpacity()

void impeller::ColorSourceContents::SetInheritedOpacity | ( | Scalar | opacity | ) |
| override virtual

Inherit the provided opacity.

       Use of this method is invalid if CanAcceptOpacity returns false.

Reimplemented from impeller::Contents.

Definition at line 49 of file color_source_contents.cc.

49 {
50 inherited_opacity_ = opacity;
51 }

## ◆ 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.

24 {
25 opacity_ = alpha;
26 }

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

impeller::Geometry::ComputeAlphaCoverage
virtual Scalar ComputeAlphaCoverage(const Matrix &transform) const
Definition: geometry.h:115
impeller::ContentContextOptions::StencilMode::kOverdrawPreventionIncrement
@ kOverdrawPreventionIncrement
impeller::Geometry::GetCoverage
virtual std::optional< Rect > GetCoverage(const Matrix &transform) const =0
impeller::BlendMode::kSource
@ kSource
impeller::BlendMode::kDestination
@ kDestination
impeller::RenderClipRestore
bool RenderClipRestore(const ContentContext &renderer, RenderPass &pass, uint32_t clip_depth, std::optional< Rect > restore_coverage)
Render a restore clip.
Definition: clip_contents.cc:152
impeller::Geometry::GetResultMode
virtual GeometryResult::Mode GetResultMode() const
Definition: geometry.cc:55
impeller::ContentContextOptions::StencilMode::kStencilEvenOddFill
@ kStencilEvenOddFill
impeller::GeometryResult::Mode::kEvenOdd
@ kEvenOdd
impeller::GeometryResult::Mode
Mode
Definition: geometry.h:22
impeller::OptionsFromPassAndEntity
ContentContextOptions OptionsFromPassAndEntity(const RenderPass &pass, const Entity &entity)
Definition: contents.cc:34
impeller::GeometryResult::type
PrimitiveType type
Definition: geometry.h:37
impeller::Geometry::GetPositionBuffer
virtual GeometryResult GetPositionBuffer(const ContentContext &renderer, const Entity &entity, RenderPass &pass) const =0
transform
Matrix transform
Definition: gaussian_blur_filter_contents.cc:214
impeller::ContentContextOptions::StencilMode::kStencilNonZeroFill
@ kStencilNonZeroFill
impeller::Rect
TRect< Scalar > Rect
Definition: rect.h:792
impeller::Matrix::Invert
Matrix Invert() const
Definition: matrix.cc:97
impeller::ColorSourceContents::GetGeometry
const Geometry * GetGeometry() const
Get the geometry that this contents will use to render.
Definition: color_source_contents.cc:20
impeller::ColorSourceContents::GetCoverage
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.
Definition: color_source_contents.cc:44
impeller::GeometryResult::Mode::kPreventOverdraw
@ kPreventOverdraw
impeller::ContentContextOptions::StencilMode::kCoverCompare
@ kCoverCompare
impeller::GeometryResult::Mode::kNonZero
@ kNonZero