treeFormat constant
Which way of describing a widget this walk writes, stamped on every tree it reads as InspectTree.format.
Bump it whenever the same widgets would read back differently — a
description spelled out where it was not, a node the walk now keeps or
drops, a key read another way. A comparison's two sides are captured by
two checkouts' own copies of this class, and the stamp is the only thing
that lets it tell a widget that changed from a walk that did: the tree
differences between two formats are carried, and do not count.
test/inspect/tree_format_test.dart fails when the reading of a fixed set
of widgets moves and this did not.
1 — the first stamped. Text.rich and RichText describe themselves
by their words, which is why the stamp exists: a tree read before it
carries none, and against one it reported every such node as changed.
2 — boxes in logical pixels on a walk rooted at the view (a run, a
scenario), where 1 reported them ×devicePixelRatio. See boxWithin.
3 — words a design library draws for the app are kept: a shown
tooltip, a field's label, a badge's count. Measured on the probe app's
text fields: three labels joined the tree, and the screen read the same
six items, each label having already been its field's words. See
_withoutDesignLibraries.
Implementation
static const treeFormat = 3;