Struct SceneBuilder 

pub struct SceneBuilder { /* private fields */ }

Builds a Scene containing the given visuals.

A Scene can then be rendered using crate::View::present.

To draw graphical operations onto a Scene, first create a Canvas, record into it, and add the resulting Picture with add_picture. Each push_* starts a container that pop builds into an EngineLayer; unbalanced pushes are a bug the builder asserts on.

Implementations

impl SceneBuilder

pub fn new() -> SceneBuilder

Creates an empty SceneBuilder object.

pub fn push_transform(&mut self, matrix4: &Matrix4)

Pushes a transform operation onto the operation stack.

The objects are transformed by the given matrix before rasterization.

pub fn push_offset(&mut self, dx: f64, dy: f64)

Pushes an offset operation onto the operation stack.

This is equivalent to push_transform with a matrix with only translation.

pub fn push_clip_rect(&mut self, rect: Rect, clip_behavior: Clip)

Pushes a rectangular clip operation onto the operation stack.

Rasterization outside the given rectangle is discarded.

pub fn push_clip_rrect(&mut self, rrect: RRect, clip_behavior: Clip)

Pushes a rounded-rectangular clip operation onto the operation stack.

Rasterization outside the given rounded rectangle is discarded.

pub fn push_clip_path(&mut self, path: &Arc<Path>, clip_behavior: Clip)

Pushes a path clip operation onto the operation stack.

Rasterization outside the given path is discarded.

pub fn push_opacity(&mut self, alpha: i32, offset: Offset)

Pushes an opacity operation onto the operation stack.

The given alpha value is blended into the alpha value of the objects’ rasterization. An alpha value of 0 makes the objects entirely invisible. An alpha value of 255 has no effect (i.e., the objects retain the current opacity).

pub fn push_backdrop_filter( &mut self, filter: &ImageFilter, blend_mode: BlendMode, backdrop_id: Option<u64>, )

Pushes a backdrop filter operation onto the operation stack.

The given filter is applied to the current contents of the scene as far back as the most recent save layer and rendered back to the scene using the indicated blend_mode prior to rasterizing the child layers.

Filters sharing a backdrop_id sample one backdrop, as Flutter’s BackdropKey groups them.

pub fn pop(&mut self) -> EngineLayer

Ends the effect of the most recently pushed operation.

The container built is the EngineLayer returned, a child of the one beneath it: the layer that pushed keeps it and hands it to add_retained while its subtree stays unchanged. dart:ui returns the engine layer from the push; a container here is built, and shared, at its pop.

Panics

If nothing is pushed.

pub fn add_embedded_layer( &mut self, layer: Arc<dyn CompositionLayer>, rect: Rect, )

Places a composition layer the host composites, at rect in the coordinates of the container being built: Flutter’s addPlatformView. It draws nothing; whoever composites the scene makes room for it at its place in paint order.

pub fn add_video(&mut self, reader: Arc<dyn VideoFrameReader>, rect: Rect)

Draws reader’s video into rect, in the coordinates of the container being built, at its place in paint order: what Flutter’s addTexture does for a texture id. Whoever draws the scene asks the reader for the frame then.

pub fn add_retained(&mut self, retained_layer: &EngineLayer)

Adds a retained EngineLayer subtree from a previous frame.

All the engine layers that are in the subtree of the retained layer will be automatically appended to the current engine layer tree: the same node, in the container being built.

pub fn add_picture( &mut self, offset: Offset, picture: &Arc<Picture>, is_complex_hint: bool, will_change_hint: bool, )

Adds a Picture to the scene.

The picture is rasterized at the given offset. The hints are for a raster cache valo does not have; they are accepted so a layer can pass what Flutter passes.

pub fn build(self) -> Scene

Finishes building the scene.

Panics

In debug builds, if a pushed operation was not popped.

Trait Implementations

impl Debug for SceneBuilder

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for SceneBuilder

fn default() -> SceneBuilder

Returns the “default value” for a type.