Flutter Impeller
impeller::SolidRRectBlurContents Class Referencefinal

Draws a fast solid color blur of an rounded rectangle. Only supports RRects with fully symmetrical radii. Also produces correct results for rectangles (corner_radius=0) and circles (corner_radius=width/2=height/2). More...

#include <solid_rrect_blur_contents.h>

Inheritance diagram for impeller::SolidRRectBlurContents:
impeller::Contents

Public Member Functions

 SolidRRectBlurContents ()
 
 ~SolidRRectBlurContents () override
 
void SetRRect (std::optional< Rect > rect, Size corner_radii={})
 
void SetSigma (Sigma sigma)
 
void SetColor (Color color)
 
Color GetColor () const
 
std::optional< RectGetCoverage (const Entity &entity) const override
 Get the area of the render pass that will be affected when this contents is rendered. More...
 
bool Render (const ContentContext &renderer, const Entity &entity, RenderPass &pass) const override
 
bool ApplyColorFilter (const ColorFilterProc &color_filter_proc) override
 If possible, applies a color filter to this contents inputs on the CPU. More...
 
- 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. 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< SnapshotRenderToSnapshot (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). More...
 
virtual bool ShouldRender (const Entity &entity, const std::optional< Rect > clip_coverage) const
 
std::optional< SizeGetColorSourceSize () 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< ColorAsBackgroundColor (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 FilterContentsAsFilter () const
 Cast to a filter. Returns nullptr if this Contents is not a filter. More...
 

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< ContentsMakeAnonymous (RenderProc render_proc, CoverageProc coverage_proc)
 

Detailed Description

Draws a fast solid color blur of an rounded rectangle. Only supports RRects with fully symmetrical radii. Also produces correct results for rectangles (corner_radius=0) and circles (corner_radius=width/2=height/2).

Definition at line 25 of file solid_rrect_blur_contents.h.

Constructor & Destructor Documentation

◆ SolidRRectBlurContents()

impeller::SolidRRectBlurContents::SolidRRectBlurContents ( )
default

◆ ~SolidRRectBlurContents()

impeller::SolidRRectBlurContents::~SolidRRectBlurContents ( )
overridedefault

Member Function Documentation

◆ ApplyColorFilter()

bool impeller::SolidRRectBlurContents::ApplyColorFilter ( const ColorFilterProc color_filter_proc)
overridevirtual

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_procA 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 from impeller::Contents.

Definition at line 132 of file solid_rrect_blur_contents.cc.

133  {
134  color_ = color_filter_proc(color_);
135  return true;
136 }

◆ GetColor()

Color impeller::SolidRRectBlurContents::GetColor ( ) const

Definition at line 43 of file solid_rrect_blur_contents.cc.

43  {
44  return color_;
45 }

◆ GetCoverage()

std::optional< Rect > impeller::SolidRRectBlurContents::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 47 of file solid_rrect_blur_contents.cc.

48  {
49  if (!rect_.has_value()) {
50  return std::nullopt;
51  }
52 
53  Scalar radius = PadForSigma(sigma_.sigma);
54 
55  return rect_->Expand(radius).TransformBounds(entity.GetTransform());
56 }

References impeller::Entity::GetTransform(), and impeller::Sigma::sigma.

◆ Render()

bool impeller::SolidRRectBlurContents::Render ( const ContentContext renderer,
const Entity entity,
RenderPass pass 
) const
overridevirtual

Implements impeller::Contents.

Definition at line 58 of file solid_rrect_blur_contents.cc.

60  {
61  if (!rect_.has_value()) {
62  return true;
63  }
64 
67 
68  VertexBufferBuilder<VS::PerVertexData> vtx_builder;
69 
70  // Clamp the max kernel width/height to 1000 to limit the extent
71  // of the blur and to kEhCloseEnough to prevent NaN calculations
72  // trying to evaluate a Guassian distribution with a sigma of 0.
73  auto blur_sigma = std::clamp(sigma_.sigma, kEhCloseEnough, 250.0f);
74  // Increase quality by making the radius a bit bigger than the typical
75  // sigma->radius conversion we use for slower blurs.
76  auto blur_radius = PadForSigma(blur_sigma);
77  auto positive_rect = rect_->GetPositive();
78  {
79  auto left = -blur_radius;
80  auto top = -blur_radius;
81  auto right = positive_rect.GetWidth() + blur_radius;
82  auto bottom = positive_rect.GetHeight() + blur_radius;
83 
84  vtx_builder.AddVertices({
85  {Point(left, top)},
86  {Point(right, top)},
87  {Point(left, bottom)},
88  {Point(right, bottom)},
89  });
90  }
91 
92  ContentContextOptions opts = OptionsFromPassAndEntity(pass, entity);
93  opts.primitive_type = PrimitiveType::kTriangleStrip;
94  Color color = color_;
95  if (entity.GetBlendMode() == BlendMode::kClear) {
96  opts.is_for_rrect_blur_clear = true;
97  color = Color::White();
98  }
99 
100  VS::FrameInfo frame_info;
101  frame_info.mvp = Entity::GetShaderTransform(
102  entity.GetShaderClipDepth(), pass,
103  entity.GetTransform() *
104  Matrix::MakeTranslation(positive_rect.GetOrigin()));
105 
106  FS::FragInfo frag_info;
107  frag_info.color = color;
108  frag_info.blur_sigma = blur_sigma;
109  frag_info.rect_size = Point(positive_rect.GetSize());
110  frag_info.corner_radii = {std::clamp(corner_radii_.width, kEhCloseEnough,
111  positive_rect.GetWidth() * 0.5f),
112  std::clamp(corner_radii_.width, kEhCloseEnough,
113  positive_rect.GetHeight() * 0.5f)};
114 
115  pass.SetCommandLabel("RRect Shadow");
116  pass.SetPipeline(renderer.GetRRectBlurPipeline(opts));
117  pass.SetStencilReference(entity.GetClipDepth());
118  pass.SetVertexBuffer(
119  vtx_builder.CreateVertexBuffer(renderer.GetTransientsBuffer()));
120  VS::BindFrameInfo(pass,
121  renderer.GetTransientsBuffer().EmplaceUniform(frame_info));
122  FS::BindFragInfo(pass,
123  renderer.GetTransientsBuffer().EmplaceUniform(frag_info));
124 
125  if (!pass.Draw().ok()) {
126  return false;
127  }
128 
129  return true;
130 }

References impeller::VertexBufferBuilder< VertexType_, IndexType_ >::AddVertices(), impeller::VertexBufferBuilder< VertexType_, IndexType_ >::CreateVertexBuffer(), impeller::RenderPass::Draw(), impeller::HostBuffer::EmplaceUniform(), impeller::Entity::GetBlendMode(), impeller::Entity::GetClipDepth(), impeller::ContentContext::GetRRectBlurPipeline(), impeller::Entity::GetShaderClipDepth(), impeller::Entity::GetShaderTransform(), impeller::Entity::GetTransform(), impeller::ContentContext::GetTransientsBuffer(), impeller::ContentContextOptions::is_for_rrect_blur_clear, impeller::kClear, impeller::kEhCloseEnough, impeller::kTriangleStrip, impeller::Matrix::MakeTranslation(), impeller::OptionsFromPassAndEntity(), impeller::ContentContextOptions::primitive_type, impeller::RenderPass::SetCommandLabel(), impeller::RenderPass::SetPipeline(), impeller::RenderPass::SetStencilReference(), impeller::RenderPass::SetVertexBuffer(), impeller::Sigma::sigma, impeller::Color::White(), and impeller::TSize< T >::width.

◆ SetColor()

void impeller::SolidRRectBlurContents::SetColor ( Color  color)

Definition at line 39 of file solid_rrect_blur_contents.cc.

39  {
40  color_ = color.Premultiply();
41 }

References impeller::Color::Premultiply().

◆ SetRRect()

void impeller::SolidRRectBlurContents::SetRRect ( std::optional< Rect rect,
Size  corner_radii = {} 
)

Definition at line 29 of file solid_rrect_blur_contents.cc.

30  {
31  rect_ = rect;
32  corner_radii_ = corner_radii;
33 }

◆ SetSigma()

void impeller::SolidRRectBlurContents::SetSigma ( Sigma  sigma)

Definition at line 35 of file solid_rrect_blur_contents.cc.

35  {
36  sigma_ = sigma;
37 }

The documentation for this class was generated from the following files:
impeller::Sigma::sigma
Scalar sigma
Definition: sigma.h:33
impeller::Entity::GetShaderTransform
Matrix GetShaderTransform(const RenderPass &pass) const
Get the vertex shader transform used for drawing this Entity.
Definition: entity.cc:53
impeller::Scalar
float Scalar
Definition: scalar.h:18
impeller::kEhCloseEnough
constexpr float kEhCloseEnough
Definition: constants.h:56
impeller::RenderPipelineT::FragmentShader
FragmentShader_ FragmentShader
Definition: pipeline.h:94
impeller::Matrix::MakeTranslation
static constexpr Matrix MakeTranslation(const Vector3 &t)
Definition: matrix.h:95
impeller::VS
SolidFillVertexShader VS
Definition: stroke_path_geometry.cc:15
impeller::OptionsFromPassAndEntity
ContentContextOptions OptionsFromPassAndEntity(const RenderPass &pass, const Entity &entity)
Definition: contents.cc:37
impeller::PrimitiveType::kTriangleStrip
@ kTriangleStrip
impeller::Point
TPoint< Scalar > Point
Definition: point.h:316
impeller::BlendMode::kClear
@ kClear
impeller::Color::White
static constexpr Color White()
Definition: color.h:256
impeller::TSize::width
Type width
Definition: size.h:22
impeller::RenderPipelineT::VertexShader
VertexShader_ VertexShader
Definition: pipeline.h:93
impeller::Color::Premultiply
constexpr Color Premultiply() const
Definition: color.h:214