mirror of
https://github.com/hajimehoshi/ebiten.git
synced 2024-09-20 05:12:18 +02:00
290 lines
6.5 KiB
Go
290 lines
6.5 KiB
Go
// Copyright 2017 The Ebiten 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 offers functions to draw texts on an Ebiten's image.
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//
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// Note: This package is experimental and API might be changed.
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package text
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import (
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"image"
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"image/color"
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"math"
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"golang.org/x/image/font"
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"golang.org/x/image/math/fixed"
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"github.com/hajimehoshi/ebiten"
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emath "github.com/hajimehoshi/ebiten/internal/math"
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"github.com/hajimehoshi/ebiten/internal/sync"
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)
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var (
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monotonicClock int64
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)
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func now() int64 {
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monotonicClock++
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return monotonicClock
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}
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var (
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charBounds = map[char]fixed.Rectangle26_6{}
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)
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type char struct {
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face font.Face
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rune rune
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}
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func (c *char) bounds() fixed.Rectangle26_6 {
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if b, ok := charBounds[*c]; ok {
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return b
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}
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b, _, _ := c.face.GlyphBounds(c.rune)
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charBounds[*c] = b
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return b
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}
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func (c *char) size() fixed.Point26_6 {
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b := c.bounds()
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return b.Max.Sub(b.Min)
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}
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func (c *char) empty() bool {
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s := c.size()
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return s.X == 0 || s.Y == 0
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}
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func (c *char) atlasGroup() int {
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s := c.size()
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w, h := s.X.Ceil(), s.Y.Ceil()
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t := w
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if t < h {
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t = h
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}
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// Different images for small runes are inefficient.
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// Let's use a same texture atlas for typical character sizes.
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if t < 32 {
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return 32
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}
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return emath.NextPowerOf2Int(t)
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}
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type glyph struct {
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char char
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index int
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atime int64
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}
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func fixed26_6ToFloat64(x fixed.Int26_6) float64 {
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return float64(x) / (1 << 6)
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}
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func (g *glyph) draw(dst *ebiten.Image, x, y fixed.Int26_6, clr color.Color) {
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cr, cg, cb, ca := clr.RGBA()
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if ca == 0 {
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return
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}
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b := g.char.bounds()
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op := &ebiten.DrawImageOptions{}
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op.GeoM.Translate(fixed26_6ToFloat64(x), fixed26_6ToFloat64(y))
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op.GeoM.Translate(fixed26_6ToFloat64(b.Min.X), fixed26_6ToFloat64(b.Min.Y))
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rf := float64(cr) / float64(ca)
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gf := float64(cg) / float64(ca)
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bf := float64(cb) / float64(ca)
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af := float64(ca) / 0xffff
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op.ColorM.Scale(rf, gf, bf, af)
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a := atlases[g.char.atlasGroup()]
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sx, sy := a.at(g)
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r := image.Rect(sx, sy, sx+a.glyphSize, sy+a.glyphSize)
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op.SourceRect = &r
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dst.DrawImage(a.image, op)
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}
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var (
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atlases = map[int]*atlas{}
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)
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type atlas struct {
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// image is the back-end image to hold glyph cache.
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image *ebiten.Image
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// tmpImage is the temporary image as a renderer source for glyph.
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tmpImage *ebiten.Image
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// glyphSize is the size of one glyph in the cache.
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// This value is always power of 2.
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glyphSize int
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charToGlyph map[char]*glyph
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}
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func (a *atlas) at(glyph *glyph) (int, int) {
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if a.glyphSize != glyph.char.atlasGroup() {
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panic("not reached")
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}
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w, _ := a.image.Size()
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xnum := w / a.glyphSize
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x, y := glyph.index%xnum, glyph.index/xnum
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return x * a.glyphSize, y * a.glyphSize
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}
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func (a *atlas) maxGlyphNum() int {
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w, h := a.image.Size()
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xnum := w / a.glyphSize
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ynum := h / a.glyphSize
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return xnum * ynum
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}
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func (a *atlas) appendGlyph(face font.Face, rune rune, now int64) *glyph {
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g := &glyph{
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char: char{face, rune},
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atime: now,
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}
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if len(a.charToGlyph) == a.maxGlyphNum() {
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var oldest *glyph
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t := int64(math.MaxInt64)
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for _, g := range a.charToGlyph {
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if g.atime < t {
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t = g.atime
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oldest = g
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}
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}
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if oldest == nil {
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panic("not reached")
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}
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idx := oldest.index
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delete(a.charToGlyph, oldest.char)
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g.index = idx
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} else {
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g.index = len(a.charToGlyph)
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}
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a.charToGlyph[g.char] = g
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a.draw(g)
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return g
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}
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func (a *atlas) draw(glyph *glyph) {
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if a.tmpImage == nil {
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a.tmpImage, _ = ebiten.NewImage(a.glyphSize, a.glyphSize, ebiten.FilterNearest)
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}
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dst := image.NewRGBA(image.Rect(0, 0, a.glyphSize, a.glyphSize))
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d := font.Drawer{
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Dst: dst,
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Src: image.White,
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Face: glyph.char.face,
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}
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b := glyph.char.bounds()
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d.Dot = fixed.Point26_6{-b.Min.X, -b.Min.Y}
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d.DrawString(string(glyph.char.rune))
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a.tmpImage.ReplacePixels(dst.Pix)
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op := &ebiten.DrawImageOptions{}
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x, y := a.at(glyph)
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op.GeoM.Translate(float64(x), float64(y))
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op.CompositeMode = ebiten.CompositeModeCopy
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a.image.DrawImage(a.tmpImage, op)
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a.tmpImage.Clear()
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}
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func getGlyphFromCache(face font.Face, r rune, now int64) *glyph {
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ch := char{face, r}
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a, ok := atlases[ch.atlasGroup()]
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if ok {
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g, ok := a.charToGlyph[ch]
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if ok {
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g.atime = now
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return g
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}
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}
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if ch.empty() {
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// The glyph doesn't have its size but might have valid 'advance' parameter
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// when ch is e.g. space (U+0020).
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return &glyph{
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char: ch,
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atime: now,
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}
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}
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if !ok {
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// Don't use ebiten.MaxImageSize here.
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// It's because the back-end image pixels will be restored from GPU
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// whenever a new glyph is rendered on the image, and restoring cost is
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// expensive if the image is big.
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// The back-end image is updated a temporary image, and the temporary image is
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// always cleared after used. This means that there is no clue to restore
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// the back-end image without reading from GPU
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// (see the package 'restorable' implementation).
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//
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// TODO: How about making a new function for 'flagile' image?
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const size = 1024
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i, _ := ebiten.NewImage(size, size, ebiten.FilterNearest)
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a = &atlas{
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image: i,
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glyphSize: ch.atlasGroup(),
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charToGlyph: map[char]*glyph{},
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}
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atlases[ch.atlasGroup()] = a
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}
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return a.appendGlyph(ch.face, ch.rune, now)
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}
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var textM sync.Mutex
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// Draw draws a given text on a given destination image dst.
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//
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// face is the font for text rendering.
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// (x, y) represents a 'dot' position. Be careful that this doesn't represent left-upper corner position.
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// clr is the color for text rendering.
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//
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// Glyphs used for rendering are cached in least-recently-used way.
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// It is OK to call this function with a same text and a same face at every frame.
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//
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// This function is concurrent-safe.
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func Draw(dst *ebiten.Image, text string, face font.Face, x, y int, clr color.Color) {
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textM.Lock()
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n := now()
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fx := fixed.I(x)
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prevC := rune(-1)
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runes := []rune(text)
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for _, c := range runes {
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if prevC >= 0 {
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fx += face.Kern(prevC, c)
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}
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if g := getGlyphFromCache(face, c, n); g != nil {
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if !g.char.empty() {
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g.draw(dst, fx, fixed.I(y), clr)
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}
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a, _ := face.GlyphAdvance(c)
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fx += a
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}
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prevC = c
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}
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textM.Unlock()
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}
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