forked from joejulian/gio
Elias Naur
bc2c3db43e
Before this change, the two renderers both had special case code for approximating strokes they don't support natively. This change moves that conversion to clip.Op.Add, for several reasons: - The compute renderer no longer need fallback logic and caches for strokes it doesn't support. - The approximation logic is slow. Moving it to clip.Op.Add will not speed it up, but will make the cost easier to spot in profiles. Until all strokes are supported natively, users can use macros to cache expensive strokes. - Reduced garbage: Op.Add takes an op.Ops anyway, and can use that for storing the approximated stroke outline. Signed-off-by: Elias Naur <mail@eliasnaur.com>
119 lines
2.6 KiB
Go
119 lines
2.6 KiB
Go
// SPDX-License-Identifier: Unlicense OR MIT
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package clip
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import (
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"encoding/binary"
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"math"
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"gioui.org/internal/opconst"
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"gioui.org/op"
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)
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// Stroke represents a stroked path.
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type Stroke struct {
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Path PathSpec
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Style StrokeStyle
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// Dashes specify the dashes of the stroke.
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// The empty value denotes no dashes.
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Dashes DashSpec
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}
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// Op returns a clip operation representing the stroke.
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func (s Stroke) Op() Op {
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return Op{
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path: s.Path,
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stroke: s.Style,
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dashes: s.Dashes,
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}
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}
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// StrokeStyle describes how a path should be stroked.
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type StrokeStyle struct {
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Width float32 // Width of the stroked path.
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// Miter is the limit to apply to a miter joint.
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// The zero Miter disables the miter joint; setting Miter to +∞
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// unconditionally enables the miter joint.
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Miter float32
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Cap StrokeCap // Cap describes the head or tail of a stroked path.
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Join StrokeJoin // Join describes how stroked paths are collated.
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}
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// StrokeCap describes the head or tail of a stroked path.
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type StrokeCap uint8
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const (
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// RoundCap caps stroked paths with a round cap, joining the right-hand and
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// left-hand sides of a stroked path with a half disc of diameter the
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// stroked path's width.
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RoundCap StrokeCap = iota
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// FlatCap caps stroked paths with a flat cap, joining the right-hand
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// and left-hand sides of a stroked path with a straight line.
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FlatCap
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// SquareCap caps stroked paths with a square cap, joining the right-hand
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// and left-hand sides of a stroked path with a half square of length
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// the stroked path's width.
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SquareCap
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)
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// StrokeJoin describes how stroked paths are collated.
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type StrokeJoin uint8
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const (
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// RoundJoin joins path segments with a round segment.
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RoundJoin StrokeJoin = iota
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// BevelJoin joins path segments with sharp bevels.
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BevelJoin
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)
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// Dash records dashes' lengths and phase for a stroked path.
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type Dash struct {
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ops *op.Ops
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macro op.MacroOp
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phase float32
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size uint8 // size of the pattern
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}
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func (d *Dash) Begin(ops *op.Ops) {
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d.ops = ops
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d.macro = op.Record(ops)
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// Write the TypeAux opcode
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data := ops.Write(opconst.TypeAuxLen)
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data[0] = byte(opconst.TypeAux)
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}
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func (d *Dash) Phase(v float32) {
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d.phase = v
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}
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func (d *Dash) Dash(length float32) {
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if d.size == math.MaxUint8 {
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panic("clip: dash pattern too large")
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}
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data := d.ops.Write(4)
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bo := binary.LittleEndian
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bo.PutUint32(data[0:], math.Float32bits(length))
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d.size++
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}
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func (d *Dash) End() DashSpec {
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c := d.macro.Stop()
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return DashSpec{
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spec: c,
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phase: d.phase,
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size: d.size,
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}
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}
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// DashSpec describes a dashed pattern.
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type DashSpec struct {
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spec op.CallOp
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phase float32
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size uint8 // size of the pattern
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}
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