UiDiagnostics

Remarks

An aggregator rather than an instrument. Every number here but the dirty regions was already published by the pass that computes it, one property at a time across the UiDocument partials — see this assembly's README § Diagnostics, where the shape and the three constraints behind it are argued. What was missing was one place to read them from, which is the whole of what doc 13's UI-debug overlay was blocked on.

⚠ It reads; it never samples. The reactive graph is single-threaded by contract, so a diagnostics surface that could touch a signal to answer a question would be able to perturb the document it is describing. Every member here is a field read or a walk of results that already exist, and none of them marks anything dirty.

⚠ And nothing on the read path allocates. A UI-debug overlay is on for minutes at a time in the frame it is diagnosing, so a surface that allocated per read would be measuring itself — which is the trap #597 is about one level up, where three boxed IReadOnlyList<T> enumerators cost a settled frame 504 bytes. This is a struct over the document, the regions come back as a span, and there is no list or string anywhere in it.

Fields and properties (15)

• public const bool RecordsRegions

  Whether this build records dirty regions at all.

• public int LayoutNodes

  How many nodes the layout tree holds.

• public int StylesResolved

  How many elements the last pass cascaded.

• public int StylesApplied

  How many had their layout style rebuilt from the result.

• public int ContainerScopesEntered

  How many container scopes the last pass entered.

• public int StyleCompactions

  How many times the style store has been compacted.

• public int SettlingPasses

  How many passes the last frame needed before nothing moved.

• public bool Settled

  Whether the document has come to rest.

• public bool LastPassWasCold

  Whether the last restyle had to resolve every element rather than a few.

• public ReadOnlySpan<UiDirtyRegion> DirtyRegions

  What invalidated the document before the pass Update most recently ran.

• public int RegionsRecorded

  How many invalidations were recorded, including any the ring had no room for.

• public int DrawListsBuilt

  How many times a surface's draw list has been rebuilt from the tree.

• public int DrawListsChanged

  How many of those rebuilds produced drawing that differs from the frame before.

• public int BrokenBindings

  How many times a binding in this document has thrown and been suspended.

• public string? LastBrokenBinding

  Where the last such binding was written, and what it threw. Null until one does.

Methods (3)

• public UiDiagnostics(UiDocument document)

  What a debug overlay may read about a document, without being able to disturb it.

• public bool TryDescribe(float x, float y, out UiElement? element, out UiBoxModel box)

  The element at a point, and its four boxes.

• public UiBoxModel BoxOf(UiElement element)

  An element's four boxes.

Used by (6)

• BrokenBindingTestsVixen.Ui.Tests
• DiagnosticsPanelVixen.Ui.Controls
• DiagnosticsPanelTestsVixen.Ui.Controls.Tests
• DiagnosticsTestsVixen.Ui.Tests
• IdleFrameWorkTestsVixen.Ui.Tests
• UiDocumentVixen.Ui