| Flutter Impeller |

Public Member Functions | List of all members
impeller::CheckerboardContents Class Referencefinal

`#include <checkerboard_contents.h>`

Inheritance diagram for impeller::CheckerboardContents:

## Public Member Functions
| CheckerboardContents ()
| ~CheckerboardContents () override
bool | Render (const ContentContext &renderer, const Entity &entity, RenderPass &pass) const override
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 | SetColor (Color color)
void | SetSquareSize (Scalar square_size)
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< 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)`. 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...

## 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

A special Contents that renders a translucent checkerboard pattern with a random color over the entire pass texture. This is useful for visualizing offscreen textures.

Definition at line 15 of file checkerboard_contents.h.

## Constructor & Destructor Documentation

## ◆ CheckerboardContents()

impeller::CheckerboardContents::CheckerboardContents | ( |  | ) |
| default

## ◆ ~CheckerboardContents()

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

## Member Function Documentation

## ◆ GetCoverage()

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

Definition at line 51 of file checkerboard_contents.cc.

52 {
53 return std::nullopt;
54 }

## ◆ Render()

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

Implements impeller::Contents.

Definition at line 18 of file checkerboard_contents.cc.

20 {
21 auto& host_buffer = renderer.GetTransientsBuffer();
22
23 using VS = CheckerboardPipeline::VertexShader;
24 using FS = CheckerboardPipeline::FragmentShader;
25
26 auto options = OptionsFromPass(pass);
27 options.blend_mode = BlendMode::kSourceOver;
28 options.stencil_mode = ContentContextOptions::StencilMode::kIgnore;
29 options.primitive_type = PrimitiveType::kTriangleStrip;
30
31 VertexBufferBuilder<typename VS::PerVertexData> vtx_builder;
32 vtx_builder.AddVertices({
33 {Point(-1, -1)},
34 {Point(1, -1)},
35 {Point(-1, 1)},
36 {Point(1, 1)},
37 });
38
39 pass.SetCommandLabel("Checkerboard");
40 pass.SetPipeline(renderer.GetCheckerboardPipeline(options));
41 pass.SetVertexBuffer(vtx_builder.CreateVertexBuffer(host_buffer));
42
43 FS::FragInfo frag_info;
44 frag_info.color = color_;
45 frag_info.square_size = square_size_;
46 FS::BindFragInfo(pass, host_buffer.EmplaceUniform(frag_info));
47
48 return pass.Draw().ok();
49 }

References impeller::VertexBufferBuilder< VertexType_, IndexType_ >::AddVertices(), impeller::VertexBufferBuilder< VertexType_, IndexType_ >::CreateVertexBuffer(), impeller::RenderPass::Draw(), impeller::ContentContext::GetTransientsBuffer(), impeller::ContentContextOptions::kIgnore, impeller::kSourceOver, impeller::kTriangleStrip, impeller::OptionsFromPass(), impeller::RenderPass::SetCommandLabel(), impeller::RenderPass::SetPipeline(), and impeller::RenderPass::SetVertexBuffer().

## ◆ SetColor()

void impeller::CheckerboardContents::SetColor | ( | Color | color | ) |

Definition at line 56 of file checkerboard_contents.cc.

56 {
57 color_ = color;
58 }

## ◆ SetSquareSize()

void impeller::CheckerboardContents::SetSquareSize | ( | Scalar | square_size | ) |

Definition at line 60 of file checkerboard_contents.cc.

60 {
61 square_size_ = square_size;
62 }

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

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

impeller::ContentContextOptions::StencilMode::kIgnore
@ kIgnore
Turn the stencil test off. Used when drawing without stencil-then-cover.
impeller::OptionsFromPass
ContentContextOptions OptionsFromPass(const RenderPass &pass)
Definition: contents.cc:20
impeller::VS
SolidFillVertexShader VS
Definition: stroke_path_geometry.cc:15
impeller::PrimitiveType::kTriangleStrip
@ kTriangleStrip
impeller::Point
TPoint< Scalar > Point
Definition: point.h:316
impeller::BlendMode::kSourceOver
@ kSourceOver