ebiten/text/v2/std.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 (
"image"
"unicode/utf8"
"golang.org/x/image/font"
"golang.org/x/image/math/fixed"
"github.com/hajimehoshi/ebiten/v2"
"github.com/hajimehoshi/ebiten/v2/vector"
)
var _ Face = (*StdFace)(nil)
type stdFaceGlyphImageCacheKey struct {
rune rune
xoffset fixed.Int26_6
// yoffset is always the same if the rune is the same, so this doesn't have to be a key.
}
// StdFace is a Face implementation for a semi-standard font.Face (golang.org/x/image/font).
// StdFace is useful to transit from existing codebase with text v1, or to use some bitmap fonts defined as font.Face.
// StdFace must not be copied by value.
type StdFace struct {
f *faceWithCache
glyphImageCache glyphImageCache[stdFaceGlyphImageCacheKey]
addr *StdFace
}
// NewStdFace creates a new StdFace from a semi-standard font.Face.
func NewStdFace(face font.Face) *StdFace {
s := &StdFace{
f: &faceWithCache{
f: face,
},
}
s.addr = s
return s
}
func (s *StdFace) copyCheck() {
if s.addr != s {
panic("text: illegal use of non-zero StdFace copied by value")
}
}
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// Metrics implements Face.
func (s *StdFace) Metrics() Metrics {
s.copyCheck()
m := s.f.Metrics()
return Metrics{
HLineGap: fixed26_6ToFloat64(m.Height - m.Ascent - m.Descent),
HAscent: fixed26_6ToFloat64(m.Ascent),
HDescent: fixed26_6ToFloat64(m.Descent),
}
}
// UnsafeInternal returns its internal font.Face.
//
// This is unsafe since this might make internal cache states out of sync.
func (s *StdFace) UnsafeInternal() font.Face {
s.copyCheck()
return s.f.f
}
// advance implements Face.
func (s *StdFace) advance(text string) float64 {
return fixed26_6ToFloat64(font.MeasureString(s.f, text))
}
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// hasGlyph implements Face.
func (s *StdFace) hasGlyph(r rune) bool {
_, ok := s.f.GlyphAdvance(r)
return ok
}
// appendGlyphsForLine implements Face.
func (s *StdFace) appendGlyphsForLine(glyphs []Glyph, line string, indexOffset int, originX, originY float64) []Glyph {
s.copyCheck()
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origin := fixed.Point26_6{
X: float64ToFixed26_6(originX),
Y: float64ToFixed26_6(originY),
}
prevR := rune(-1)
for i, r := range line {
if prevR >= 0 {
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origin.X += s.f.Kern(prevR, r)
}
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img, imgX, imgY, a := s.glyphImage(r, origin)
// Adjust the position to the integers.
// The current glyph images assume that they are rendered on integer positions so far.
_, size := utf8.DecodeRuneInString(line[i:])
// Append a glyph even if img is nil.
// This is necessary to return index information for control characters.
glyphs = append(glyphs, Glyph{
StartIndexInBytes: indexOffset + i,
EndIndexInBytes: indexOffset + i + size,
Image: img,
X: float64(imgX),
Y: float64(imgY),
})
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origin.X += a
prevR = r
}
return glyphs
}
func (s *StdFace) glyphImage(r rune, origin fixed.Point26_6) (*ebiten.Image, int, int, fixed.Int26_6) {
// Assume that StdFace's direction is always horizontal.
origin.X = adjustGranularity(origin.X, s)
origin.Y &^= ((1 << 6) - 1)
b, a, _ := s.f.GlyphBounds(r)
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subpixelOffset := fixed.Point26_6{
X: (origin.X + b.Min.X) & ((1 << 6) - 1),
Y: (origin.Y + b.Min.Y) & ((1 << 6) - 1),
}
key := stdFaceGlyphImageCacheKey{
rune: r,
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xoffset: subpixelOffset.X,
}
img := s.glyphImageCache.getOrCreate(s, key, func() *ebiten.Image {
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return s.glyphImageImpl(r, subpixelOffset, b)
})
imgX := (origin.X + b.Min.X).Floor()
imgY := (origin.Y + b.Min.Y).Floor()
return img, imgX, imgY, a
}
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func (s *StdFace) glyphImageImpl(r rune, subpixelOffset fixed.Point26_6, glyphBounds fixed.Rectangle26_6) *ebiten.Image {
w, h := (glyphBounds.Max.X - glyphBounds.Min.X).Ceil(), (glyphBounds.Max.Y - glyphBounds.Min.Y).Ceil()
if w == 0 || h == 0 {
return nil
}
// Add always 1 to the size.
// In theory, it is possible to determine whether +1 is necessary or not, but the calculation is pretty complicated.
w++
h++
rgba := image.NewRGBA(image.Rect(0, 0, w, h))
d := font.Drawer{
Dst: rgba,
Src: image.White,
Face: s.f,
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Dot: fixed.Point26_6{
X: -glyphBounds.Min.X + subpixelOffset.X,
Y: -glyphBounds.Min.Y + subpixelOffset.Y,
},
}
d.DrawString(string(r))
return ebiten.NewImageFromImage(rgba)
}
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// direction implements Face.
func (s *StdFace) direction() Direction {
return DirectionLeftToRight
}
// appendVectorPathForLine implements Face.
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func (s *StdFace) appendVectorPathForLine(path *vector.Path, line string, originX, originY float64) {
}
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// Metrics implements Face.
func (s *StdFace) private() {
}