ebiten/text/v2/limited.go

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// Copyright 2023 The Ebitengine Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package text
import (
"github.com/hajimehoshi/ebiten/v2/vector"
)
var _ Face = (*LimitedFace)(nil)
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// LimitedFace is a Face with glyph limitations.
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type LimitedFace struct {
face Face
unicodeRanges unicodeRanges
}
// NewLimitedFace creates a new LimitedFace from the given face.
// In the default state, glyphs for any runes are limited and not rendered.
// You have to call AddUnicodeRange to add allowed glyphs.
func NewLimitedFace(face Face) *LimitedFace {
return &LimitedFace{
face: face,
}
}
// AddUnicodeRange adds a rune range for rendered glyphs.
// A range is inclusive, which means that a range contains the specified rune end.
func (l *LimitedFace) AddUnicodeRange(start, end rune) {
l.unicodeRanges.add(start, end)
}
// Metrics implements Face.
func (l *LimitedFace) Metrics() Metrics {
return l.face.Metrics()
}
// advance implements Face.
func (l *LimitedFace) advance(text string) float64 {
return l.face.advance(l.unicodeRanges.filter(text))
}
// hasGlyph implements Face.
func (l *LimitedFace) hasGlyph(r rune) bool {
return l.unicodeRanges.contains(r) && l.face.hasGlyph(r)
}
// appendGlyphsForLine implements Face.
func (l *LimitedFace) appendGlyphsForLine(glyphs []Glyph, line string, indexOffset int, originX, originY float64) []Glyph {
return l.face.appendGlyphsForLine(glyphs, l.unicodeRanges.filter(line), indexOffset, originX, originY)
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}
// appendVectorPathForLine implements Face.
func (l *LimitedFace) appendVectorPathForLine(path *vector.Path, line string, originX, originY float64) {
l.face.appendVectorPathForLine(path, l.unicodeRanges.filter(line), originX, originY)
}
// direction implements Face.
func (l *LimitedFace) direction() Direction {
return l.face.direction()
}
// private implements Face.
func (l *LimitedFace) private() {
}
type unicodeRange struct {
start rune
end rune
}
type unicodeRanges struct {
ranges []unicodeRange
}
func (u *unicodeRanges) add(start, end rune) {
u.ranges = append(u.ranges, unicodeRange{
start: start,
end: end,
})
}
func (u *unicodeRanges) contains(r rune) bool {
for _, rg := range u.ranges {
if rg.start <= r && r <= rg.end {
return true
}
}
return false
}
func (u *unicodeRanges) filter(str string) string {
var rs []rune
for _, r := range str {
if !u.contains(r) {
// U+FFFD is "REPLACEMENT CHARACTER".
r = '\ufffd'
}
rs = append(rs, r)
}
return string(rs)
}