mirror of
https://git.sr.ht/~eliasnaur/gio
synced 2026-07-01 07:35:40 +00:00
Dominik Honnef
b4d93379c4
When storing a string in an interface value that escapes, Go has to heap allocate space for the string header, as interface values can only store pointers. In text-heavy applications, this can lead to hundreds of allocations per frame due to semantic.LabelOp, the primary user of string-typed references in ops. Instead of allocating each string header individually, provide a slice of strings to store string-typed references in, and store pointers into this slice as the actual references. This only allocates when resizing the slice's backing array, and averages out to no allocations, as the backing array gets reused between calls to Ops.Reset. We introduce two new functions, Write1String and Write2String, which make use of this new slice for their last argument. We could've automated this in the existing Write1 and Write2 methods, but that would require type assertions on each call, and the vast majority of ops do not make use of strings. Signed-off-by: Dominik Honnef <dominik@honnef.co>
92 lines
2.0 KiB
Go
92 lines
2.0 KiB
Go
// SPDX-License-Identifier: Unlicense OR MIT
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// Package semantic provides operations for semantic descriptions of a user
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// interface, to facilitate presentation and interaction in external software
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// such as screen readers.
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//
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// Semantic descriptions are organized in a tree, with clip operations as
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// nodes. Operations in this package are associated with the current semantic
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// node, that is the most recent pushed clip operation.
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package semantic
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import (
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"gioui.org/internal/ops"
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"gioui.org/op"
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)
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// LabelOp provides the content of a textual component.
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type LabelOp string
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// DescriptionOp describes a component.
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type DescriptionOp string
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// ClassOp provides the component class.
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type ClassOp int
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const (
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Unknown ClassOp = iota
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Button
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CheckBox
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Editor
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RadioButton
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Switch
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)
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// SelectedOp describes the selected state for components that have
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// boolean state.
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type SelectedOp bool
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// DisabledOp describes the disabled state.
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type DisabledOp bool
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func (l LabelOp) Add(o *op.Ops) {
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data := ops.Write1String(&o.Internal, ops.TypeSemanticLabelLen, string(l))
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data[0] = byte(ops.TypeSemanticLabel)
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}
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func (d DescriptionOp) Add(o *op.Ops) {
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data := ops.Write1String(&o.Internal, ops.TypeSemanticDescLen, string(d))
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data[0] = byte(ops.TypeSemanticDesc)
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}
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func (c ClassOp) Add(o *op.Ops) {
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data := ops.Write(&o.Internal, ops.TypeSemanticClassLen)
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data[0] = byte(ops.TypeSemanticClass)
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data[1] = byte(c)
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}
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func (s SelectedOp) Add(o *op.Ops) {
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data := ops.Write(&o.Internal, ops.TypeSemanticSelectedLen)
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data[0] = byte(ops.TypeSemanticSelected)
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if s {
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data[1] = 1
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}
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}
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func (d DisabledOp) Add(o *op.Ops) {
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data := ops.Write(&o.Internal, ops.TypeSemanticDisabledLen)
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data[0] = byte(ops.TypeSemanticDisabled)
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if d {
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data[1] = 1
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}
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}
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func (c ClassOp) String() string {
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switch c {
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case Unknown:
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return "Unknown"
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case Button:
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return "Button"
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case CheckBox:
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return "CheckBox"
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case Editor:
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return "Editor"
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case RadioButton:
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return "RadioButton"
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case Switch:
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return "Switch"
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default:
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panic("invalid ClassOp")
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}
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}
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