FakeBackend class final

A device that records rather than draws.

Implemented types

• GraphicsDevice

Constructors

FakeBackend({Set<String> missingShaders = const <String>{}, bool supportsWireframe = true, bool supportsStencil = true, bool supportsRenderToMip = true, Set<TextureFormat> unsupportedFormats = const <TextureFormat>{}, int maxAnisotropy = 16, int maxColorAttachments = 2, Map<String, StageBindings>? stageBindings, FramebufferOrigin framebufferOrigin = FramebufferOrigin.topLeft})

Properties

answerReadback ↔ ByteData Function(TextureHandle texture, ScreenRect region)?

What a readback answers, or null for a region of zeros.

getter/setter pair

bindingViolations → List<String>

Declared slots left unbound at a draw, across every pass. See stageBindings.

final

completesImmediately ↔ bool

Whether onFrameComplete runs its callback at once.

getter/setter pair

createdCubeRenderTargets → List<({TextureFormat format, int mipLevels, int size})>

Every cube a pass may draw into, with the level count it was asked for, so a test can see that a probe allocated what it meant to.

final

createdTextures → List<RenderTargetSpec>

final

defaultColorFormat → TextureFormat

The colour format this device prefers.

no setter, override

defaultDepthStencilFormat → TextureFormat

The depth/stencil format this device prefers. Legitimately TextureFormat.unknown on a context that has none.

no setter, override

depthRange → DepthRange

What this backend's clip space maps depth onto.

no setter, override

disposed ↔ bool

Whether dispose has been called, for a test that wants to assert a device was actually torn down rather than merely dropped.

getter/setter pair

framebufferOrigin → FramebufferOrigin

The engine's own convention by default, so a fake never exercises the remap. The backends that need the other one are covered by running them; a test that pins what the engine hands such a backend asks for FramebufferOrigin.bottomLeft.

final

frames ↔ int

getter/setter pair

hashCode → int

The hash code for this object.

no setter, inherited

hdrColorFormat → TextureFormat

The format to render high dynamic range colour into.

no setter, override

hdrOutputFormats → List<TextureFormat>

The formats this device can present an extended-range frame in, empty when it can only present standard range.

no setter, override

linkedPipelines → List<String>

Every pair linked so far, by name and in order, so a test can tell whether a frame linked anything — a renderer that relinked drops every pipeline it held and links each one again, and one it forgot to drop shows up here as a link that did not happen.

final

loadedLibraries → List<FakeLoadedShaderLibrary>

Every library loadShaders has handed out, in order, so a test can reach the one an application holds and count its refreshes.

final

maxAnisotropy → int

Sixteen, which is what most hardware answers, and settable so a test can be the device that answers one and see what a caller clamps to.

final

maxColorAttachments → int

Two, and settable so a test can be the device that answers one — gfx-50n.

final

overwrites → List<({Object backend, int lengthInBytes, int offsetInBytes})>

Every call overwriteGeometry has recorded, in order — a test asks this rather than the bytes themselves, because this backend keeps none: it records wiring, not content, the same promise uploads already makes.

final

overwrittenTextures → List<({TextureFormat format, int mipLevel, ScreenRect region})>

Every call overwriteTexture has recorded, in order — wiring, not content, the same promise uploadedPixels already makes for a whole upload.

final

passes → List<FakePass>

Every pass ever opened, in the order it was opened.

final

pendingFrames → List<void Function()>

Frames whose work the GPU has not "finished".

final

preferredSampleCount → int

Samples to use for multisampled targets, or 1 for none.

no setter, override

readbacks → List<({ScreenRect region, TextureHandle texture})>

Every readback asked for, in order: which texture and which region.

final

releasedGeometry → List<GeometryBuffer>

final

releasedTextures → List<TextureHandle>

What was handed back one at a time, in the order it was handed back.

final

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

shaders → FakeShaderLibrary

The compiled bundle this device was built with.

final

stageBindings → Map<String, StageBindings>?

What each stage declares, by name, or null to accept every bind.

final

supportsBlendColor → bool

Whether PassEncoder.setBlendColor reaches the hardware.

no setter, override

supportsCompute → bool

Whether compute pipelines can be created and dispatched — H6. The members below it throw an UnsupportedError where this is false.

no setter, override

supportsCubeTextures → bool

Whether a cube texture can be created and sampled.

no setter, override

supportsFloat32Filtering → bool

Whether a 32-bit float texture can be drawn into and sampled with linear filtering.

no setter, override

supportsGpuTimestamps → bool

Whether this device measures how long the GPU spends in each labelled pass — H2. When true, onGpuTimings is called with them.

no setter, override

supportsIndependentBlend → bool

Whether a pass with several colour targets can blend each differently.

no setter, override

supportsMipmaps → bool

True, because a fake has nothing to be incapable with. The real answer is a device property, and the two backends that have one disagree.

no setter, override

supportsOffscreenMsaa ↔ bool

True, and settable so a test can be the device that answers no — gfx-20n.

getter/setter pair, override-getter

supportsRenderToMip → bool

Settable for the same reason supportsWireframe is: the interesting case is the backend that says no — flutter_gpu on OpenGL ES — and the renderer is supposed to build a probe without a chain there rather than name a level the device will refuse.

final

supportsStencil → bool

Settable for the same reason supportsWireframe is: the case worth a test is the device that says no, where the x-ray stage has to draw nothing rather than configure a test against an attachment with no stencil in it.

final

supportsWireframe → bool

Settable, because the interesting case is the backend that says no — OpenGL ES has no glPolygonMode, and the engine is supposed to decline its own wireframe setting rather than let the request reach a backend that would refuse it mid-frame.

final

unsupportedFormats → Set<TextureFormat>

The formats this fake says it cannot sample, so a test can be the device that has no BC7 and see what a loader does about it.

final

uploadedMipLevels → List<List<ByteData>?>

The chain each of those came with — null for an upload that brought none — so a test can tell a base level from a base level and its mips.

final

uploadedPixels → List<ByteData>

The bytes of each of those, for a test that cares what colour it was.

final

uploadedTextures → List<RenderTargetSpec>

Pixel uploads, in order, so a test can assert what reached the device.

final

uploads → List<GeometryUsage>

Recorded with its usage, because a backend exists that cannot change its mind about one later.

final

Methods

beginComputePass({String? label}) → ComputeEncoder

Opens a compute pass; label names it to a debugger and to onGpuTimings.

override

beginFrame() → void

Tells the backend a new frame is starting.

override

beginRenderPass(RenderPassDescriptor descriptor) → CommandEncoder

Opens a pass and returns the encoder that records into it.

override

createComputePipeline(ShaderHandle shader) → ComputePipelineHandle

A pipeline from a compute stage of this device's shader library.

override

createCubeRenderTarget({required int size, required TextureFormat format, int mipLevels = 1}) → TextureHandle?

Allocates a cube texture a pass can draw into, face by face and level by level, with nothing in it yet.

override

createCubeTextureFromPixels({required int size, required TextureFormat format, required List<ByteData> faces, List<List<ByteData>>? mipLevels}) → TextureHandle?

Uploads six square images as one cube texture.

override

createPipeline(ShaderHandle vertex, ShaderHandle fragment, {VertexLayoutSpec? layout}) → PipelineHandle

Links two stages into something that can be bound.

override

createStorageBuffer(ByteData bytes, {bool hostReadable = false}) → StorageBuffer

A storage buffer holding bytes. hostReadable allows readBuffer.

override

createTexture(RenderTargetSpec spec) → TextureHandle

A brand-new texture matching spec, with the single TextureHandle that will ever stand for it.

override

createTextureFromPixels({required int width, required int height, required TextureFormat format, required ByteData pixels, List<ByteData>? mipLevels}) → TextureHandle?

Creates a texture already holding pixels.

override

dispose() → void

Releases every persistent resource this device holds — the textures and geometry buffers handed out by createTexture, createTextureFromPixels, createCubeTextureFromPixels, createCubeRenderTarget and uploadGeometry.

override

finishOldestFrame() → void

Lets the oldest unfinished frame complete.

loadShaders(ByteData bytes) → Future<LoadedShaderLibrary>

Decodes the bundle — so bytes that are not one are refused the way every real backend refuses them — and answers its names. No section is read: a fake compiles nothing, which is also the software rasteriser's answer.

override

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

onFrameComplete(void whenDone()) → void

Runs whenDone once the GPU has finished with the frame being encoded now.

override

onGpuTimings(void listener(GpuFrameTimings timings)?) → void

Sets where each frame's GPU timings go, a frame or two after it was encoded; null stops them. Never called on a device whose supportsGpuTimestamps is false.

override

overwriteGeometry(GeometryBuffer target, int offsetInBytes, ByteData bytes) → void

Writes bytes into target starting offsetInBytes into it, in place.

override

overwriteTexture(TextureHandle target, ByteData rgba, {ScreenRect? region, int mipLevel = 0}) → Future<void>

Overwrites region (the whole texture by default) of target's base level with rgba — raw RGBA8 bytes, region.width * region.height * 4 of them, row-major from the top the same way readback answers them.

override

readback(TextureHandle texture, {ScreenRect? region}) → Future<ByteData>

Refuses what the contract refuses, records the rest, and answers zeros unless answerReadback says otherwise.

override

readBuffer(StorageBuffer buffer) → Future<ByteData>

The contents of buffer, once every pass submitted before this call has finished writing it. buffer must be hostReadable.

override

readPixels(TextureHandle texture) → Future<ByteData?>

Null, which is a legitimate answer rather than a refusal: it is what a real device says about a texture whose pixels cannot be read.

override

releaseGeometry(GeometryBuffer geometry) → void

Releases one geometry buffer, rather than waiting for the whole device to go.

override

releaseStorageBuffer(StorageBuffer buffer) → void

Releases one storage buffer, as releaseGeometry releases geometry.

override

releaseTexture(TextureHandle texture) → void

Gives one back, rather than waiting for the whole device to go.

override

supportsTextureFormat(TextureFormat format) → bool

Whether a texture uploaded in format can be created and sampled here.

override

toString() → String

A string representation of this object.

inherited

uploadGeometry(ByteData bytes, GeometryUsage usage) → GeometryBuffer

Uploads geometry that will outlive the frame.

override

Operators

operator ==(Object other) → bool

The equality operator.

inherited