mirror of
https://github.com/hajimehoshi/ebiten.git
synced 2024-12-26 11:48:55 +01:00
384 lines
10 KiB
Go
384 lines
10 KiB
Go
// Copyright 2023 The Ebitengine Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package text
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import (
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"bytes"
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"encoding/binary"
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"fmt"
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"strings"
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"github.com/go-text/typesetting/di"
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glanguage "github.com/go-text/typesetting/language"
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"github.com/go-text/typesetting/opentype/api/font"
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"github.com/go-text/typesetting/opentype/loader"
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"github.com/go-text/typesetting/shaping"
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"golang.org/x/image/math/fixed"
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"golang.org/x/text/language"
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"github.com/hajimehoshi/ebiten/v2"
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"github.com/hajimehoshi/ebiten/v2/vector"
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)
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var _ Face = (*GoTextFace)(nil)
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// GoTextFace is a Face implementation for go-text's font.Face (github.com/go-text/typesetting).
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// With a GoTextFace, shaping.HarfBuzzShaper is always used as a shaper internally.
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// GoTextFace includes the source and various options.
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type GoTextFace struct {
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// Source is the font face source.
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Source *GoTextFaceSource
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// Direction is the rendering direction.
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// The default (zero) value is left-to-right horizontal.
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Direction Direction
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// Size is the font size in pixels.
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Size float64
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// Language is a hiint for a language (BCP 47).
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Language language.Tag
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// Script is a hint for a script code hint of (ISO 15924).
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// If this is empty, the script is guessed from the specified language.
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Script language.Script
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variations []font.Variation
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features []shaping.FontFeature
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variationsString string
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featuresString string
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}
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// SetVariation sets a variation value.
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// For font variations, see https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_fonts/Variable_fonts_guide for more details.
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func (g *GoTextFace) SetVariation(tag Tag, value float32) {
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idx := len(g.variations)
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for i, v := range g.variations {
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if uint32(v.Tag) < uint32(tag) {
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continue
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}
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if uint32(v.Tag) > uint32(tag) {
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idx = i
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break
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}
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if v.Value == value {
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return
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}
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g.variations[i].Value = value
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g.variationsString = ""
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return
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}
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// Keep the alphabetical order in order to make the cache key deterministic.
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g.variations = append(g.variations, font.Variation{})
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copy(g.variations[idx+1:], g.variations[idx:])
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g.variations[idx] = font.Variation{
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Tag: loader.Tag(tag),
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Value: value,
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}
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g.variationsString = ""
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}
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// RemoveVariation removes a variation value.
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func (g *GoTextFace) RemoveVariation(tag Tag) {
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for i, v := range g.variations {
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if uint32(v.Tag) < uint32(tag) {
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continue
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}
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if uint32(v.Tag) > uint32(tag) {
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return
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}
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copy(g.variations[i:], g.variations[i+1:])
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g.variations = g.variations[:len(g.variations)-1]
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g.variationsString = ""
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return
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}
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}
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// SetFeature sets a feature value.
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// For font features, see https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_fonts/OpenType_fonts_guide for more details.
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func (g *GoTextFace) SetFeature(tag Tag, value uint32) {
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idx := len(g.features)
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for i, f := range g.features {
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if uint32(f.Tag) < uint32(tag) {
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continue
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}
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if uint32(f.Tag) > uint32(tag) {
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idx = i
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break
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}
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if f.Value == value {
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return
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}
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g.features[i].Value = value
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g.featuresString = ""
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return
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}
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// Keep the alphabetical order in order to make the cache key deterministic.
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g.features = append(g.features, shaping.FontFeature{})
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copy(g.features[idx+1:], g.features[idx:])
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g.features[idx] = shaping.FontFeature{
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Tag: loader.Tag(tag),
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Value: value,
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}
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g.featuresString = ""
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}
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// RemoveFeature removes a feature value.
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func (g *GoTextFace) RemoveFeature(tag Tag) {
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for i, v := range g.features {
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if uint32(v.Tag) < uint32(tag) {
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continue
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}
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if uint32(v.Tag) > uint32(tag) {
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return
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}
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copy(g.features[i:], g.features[i+1:])
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g.features = g.features[:len(g.features)-1]
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g.featuresString = ""
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return
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}
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}
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// Tag is a tag for font variations and features.
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// Tag is a 4-byte value like 'cmap'.
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type Tag uint32
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// String returns the Tag's string representation.
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func (t Tag) String() string {
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return string([]byte{byte(t >> 24), byte(t >> 16), byte(t >> 8), byte(t)})
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}
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// PraseTag converts a string to Tag.
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func ParseTag(str string) (Tag, error) {
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if len(str) != 4 {
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return 0, fmt.Errorf("text: a string's length must be 4 but was %d at ParseTag", len(str))
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}
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return Tag((uint32(str[0]) << 24) | (uint32(str[1]) << 16) | (uint32(str[2]) << 8) | uint32(str[3])), nil
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}
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// MustPraseTag converts a string to Tag.
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// If parsing fails, MustParseTag panics.
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func MustParseTag(str string) Tag {
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t, err := ParseTag(str)
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if err != nil {
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panic(err)
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}
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return t
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}
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// Metrics implements Face.
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func (g *GoTextFace) Metrics() Metrics {
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scale := g.Source.scale(g.Size)
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var m Metrics
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if h, ok := g.Source.f.FontHExtents(); ok {
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m.HLineGap = float64(h.LineGap) * scale
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m.HAscent = float64(h.Ascender) * scale
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m.HDescent = float64(-h.Descender) * scale
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}
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if v, ok := g.Source.f.FontVExtents(); ok {
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m.VLineGap = float64(v.LineGap) * scale
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m.VAscent = float64(v.Ascender) * scale
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m.VDescent = float64(-v.Descender) * scale
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}
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return m
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}
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func (g *GoTextFace) ensureVariationsString() string {
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if g.variationsString != "" {
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return g.variationsString
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}
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if len(g.variations) == 0 {
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return ""
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}
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var buf bytes.Buffer
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for _, t := range g.variations {
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_ = binary.Write(&buf, binary.LittleEndian, t.Tag)
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_ = binary.Write(&buf, binary.LittleEndian, t.Value)
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}
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g.variationsString = buf.String()
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return g.variationsString
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}
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func (g *GoTextFace) ensureFeaturesString() string {
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if g.featuresString != "" {
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return g.featuresString
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}
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if len(g.features) == 0 {
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return ""
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}
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var buf bytes.Buffer
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for _, t := range g.features {
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_ = binary.Write(&buf, binary.LittleEndian, t.Tag)
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_ = binary.Write(&buf, binary.LittleEndian, t.Value)
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}
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g.featuresString = buf.String()
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return g.featuresString
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}
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func (g *GoTextFace) outputCacheKey(text string) goTextOutputCacheKey {
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return goTextOutputCacheKey{
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text: text,
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direction: g.Direction,
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size: g.Size,
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language: g.Language.String(),
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script: g.Script.String(),
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variations: g.ensureVariationsString(),
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features: g.ensureFeaturesString(),
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}
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}
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func (g *GoTextFace) diDirection() di.Direction {
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switch g.Direction {
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case DirectionLeftToRight:
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return di.DirectionLTR
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case DirectionRightToLeft:
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return di.DirectionRTL
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default:
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return di.DirectionTTB
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}
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}
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func (g *GoTextFace) gScript() glanguage.Script {
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var str string
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if g.Script != (language.Script{}) {
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str = g.Script.String()
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} else {
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s, _ := g.Language.Script()
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str = s.String()
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}
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// ISO 15924 itself is case-insensitive [1], but go-text uses small-caps.
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// [1] https://www.unicode.org/iso15924/faq.html#17
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str = strings.ToLower(str)
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s, err := glanguage.ParseScript(str)
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if err != nil {
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panic(err)
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}
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return s
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}
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// advance implements Face.
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func (g *GoTextFace) advance(text string) float64 {
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outputs, _ := g.Source.shape(text, g)
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var a fixed.Int26_6
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for _, output := range outputs {
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a += output.Advance
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}
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if g.direction().isHorizontal() {
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return fixed26_6ToFloat64(a)
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}
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return -fixed26_6ToFloat64(a)
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}
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// hasGlyph implements Face.
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func (g *GoTextFace) hasGlyph(r rune) bool {
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_, ok := g.Source.f.Cmap.Lookup(r)
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return ok
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}
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// appendGlyphsForLine implements Face.
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func (g *GoTextFace) appendGlyphsForLine(glyphs []Glyph, line string, indexOffset int, originX, originY float64) []Glyph {
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origin := fixed.Point26_6{
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X: float64ToFixed26_6(originX),
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Y: float64ToFixed26_6(originY),
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}
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_, gs := g.Source.shape(line, g)
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for _, glyph := range gs {
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img, imgX, imgY := g.glyphImage(glyph, origin.Add(fixed.Point26_6{
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X: glyph.shapingGlyph.XOffset,
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Y: -glyph.shapingGlyph.YOffset,
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}))
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// Append a glyph even if img is nil.
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// This is necessary to return index information for control characters.
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glyphs = append(glyphs, Glyph{
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StartIndexInBytes: indexOffset + glyph.startIndex,
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EndIndexInBytes: indexOffset + glyph.endIndex,
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GID: uint32(glyph.shapingGlyph.GlyphID),
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Image: img,
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X: float64(imgX),
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Y: float64(imgY),
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})
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origin = origin.Add(fixed.Point26_6{
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X: glyph.shapingGlyph.XAdvance,
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Y: -glyph.shapingGlyph.YAdvance,
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})
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}
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return glyphs
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}
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func (g *GoTextFace) glyphImage(glyph glyph, origin fixed.Point26_6) (*ebiten.Image, int, int) {
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if g.direction().isHorizontal() {
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origin.X = adjustGranularity(origin.X, g)
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origin.Y &^= ((1 << 6) - 1)
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} else {
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origin.X &^= ((1 << 6) - 1)
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origin.Y = adjustGranularity(origin.Y, g)
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}
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b := glyph.bounds
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subpixelOffset := fixed.Point26_6{
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X: (origin.X + b.Min.X) & ((1 << 6) - 1),
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Y: (origin.Y + b.Min.Y) & ((1 << 6) - 1),
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}
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key := goTextGlyphImageCacheKey{
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gid: glyph.shapingGlyph.GlyphID,
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xoffset: subpixelOffset.X,
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yoffset: subpixelOffset.Y,
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variations: g.ensureVariationsString(),
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}
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img := g.Source.getOrCreateGlyphImage(g, key, func() *ebiten.Image {
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return segmentsToImage(glyph.scaledSegments, subpixelOffset, b)
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})
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imgX := (origin.X + b.Min.X).Floor()
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imgY := (origin.Y + b.Min.Y).Floor()
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return img, imgX, imgY
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}
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// appendVectorPathForLine implements Face.
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func (g *GoTextFace) appendVectorPathForLine(path *vector.Path, line string, originX, originY float64) {
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origin := fixed.Point26_6{
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X: float64ToFixed26_6(originX),
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Y: float64ToFixed26_6(originY),
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}
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_, gs := g.Source.shape(line, g)
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for _, glyph := range gs {
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appendVectorPathFromSegments(path, glyph.scaledSegments, fixed26_6ToFloat32(origin.X), fixed26_6ToFloat32(origin.Y))
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origin = origin.Add(fixed.Point26_6{
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X: glyph.shapingGlyph.XAdvance,
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Y: -glyph.shapingGlyph.YAdvance,
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})
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}
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}
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// direction implements Face.
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func (g *GoTextFace) direction() Direction {
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return g.Direction
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}
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// private implements Face.
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func (g *GoTextFace) private() {
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}
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