mirror of
https://github.com/hajimehoshi/ebiten.git
synced 2024-12-26 03:38:55 +01:00
276 lines
7.1 KiB
Go
276 lines
7.1 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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// For the example using a TTF font, see font package in the examples.
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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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"sync"
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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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"github.com/hajimehoshi/ebiten/internal/colormcache"
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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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func fixed26_6ToFloat64(x fixed.Int26_6) float64 {
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return float64(x>>6) + float64(x&((1<<6)-1))/float64(1<<6)
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}
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const (
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cacheLimit = 512 // This is an arbitrary number.
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)
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func drawGlyph(dst *ebiten.Image, face font.Face, r rune, img *ebiten.Image, x, y fixed.Int26_6, clr ebiten.ColorM) {
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if img == nil {
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return
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}
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b := getGlyphBounds(face, r)
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op := &ebiten.DrawImageOptions{}
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op.GeoM.Translate(fixed26_6ToFloat64((x + b.Min.X)), fixed26_6ToFloat64((y + b.Min.Y)))
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op.ColorM = clr
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_ = dst.DrawImage(img, op)
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}
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var (
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// Use pointers as copying is expensive on GopherJS.
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glyphBoundsCache = map[font.Face]map[rune]*fixed.Rectangle26_6{}
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)
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func getGlyphBounds(face font.Face, r rune) *fixed.Rectangle26_6 {
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if _, ok := glyphBoundsCache[face]; !ok {
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glyphBoundsCache[face] = map[rune]*fixed.Rectangle26_6{}
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}
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if b, ok := glyphBoundsCache[face][r]; ok {
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return b
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}
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b, _, _ := face.GlyphBounds(r)
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glyphBoundsCache[face][r] = &b
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return &b
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}
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type glyphImageCacheEntry struct {
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image *ebiten.Image
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atime int64
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}
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var (
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glyphImageCache = map[font.Face]map[rune]*glyphImageCacheEntry{}
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emptyGlyphs = map[font.Face]map[rune]struct{}{}
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)
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func getGlyphImages(face font.Face, runes []rune) []*ebiten.Image {
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if _, ok := emptyGlyphs[face]; !ok {
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emptyGlyphs[face] = map[rune]struct{}{}
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}
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if _, ok := glyphImageCache[face]; !ok {
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glyphImageCache[face] = map[rune]*glyphImageCacheEntry{}
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}
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imgs := make([]*ebiten.Image, len(runes))
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glyphBounds := map[rune]*fixed.Rectangle26_6{}
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neededGlyphIndices := map[int]rune{}
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for i, r := range runes {
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if _, ok := emptyGlyphs[face][r]; ok {
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continue
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}
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if e, ok := glyphImageCache[face][r]; ok {
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e.atime = now()
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imgs[i] = e.image
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continue
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}
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b := getGlyphBounds(face, r)
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w, h := (b.Max.X - b.Min.X).Ceil(), (b.Max.Y - b.Min.Y).Ceil()
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if w == 0 || h == 0 {
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emptyGlyphs[face][r] = struct{}{}
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continue
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}
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// TODO: What if len(runes) > cacheLimit?
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if len(glyphImageCache[face]) > cacheLimit {
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oldest := int64(math.MaxInt64)
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oldestKey := rune(-1)
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for r, e := range glyphImageCache[face] {
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if e.atime < oldest {
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oldestKey = r
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oldest = e.atime
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}
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}
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delete(glyphImageCache[face], oldestKey)
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}
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glyphBounds[r] = b
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neededGlyphIndices[i] = r
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}
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if len(neededGlyphIndices) > 0 {
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for i, r := range neededGlyphIndices {
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b := glyphBounds[r]
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w, h := (b.Max.X - b.Min.X).Ceil(), (b.Max.Y - b.Min.Y).Ceil()
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rgba := image.NewRGBA(image.Rect(0, 0, w, h))
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d := font.Drawer{
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Dst: rgba,
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Src: image.White,
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Face: face,
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}
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d.Dot = fixed.Point26_6{X: -b.Min.X, Y: -b.Min.Y}
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d.DrawString(string(r))
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img, _ := ebiten.NewImageFromImage(rgba, ebiten.FilterDefault)
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if _, ok := glyphImageCache[face][r]; !ok {
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glyphImageCache[face][r] = &glyphImageCacheEntry{
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image: img,
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atime: now(),
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}
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}
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imgs[i] = img
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}
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}
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return imgs
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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' (period) position.
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// This means that if the given text consisted of a single character ".",
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// it would be positioned at the given position (x, y).
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// Be careful that this doesn't represent left-upper corner position.
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//
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// clr is the color for text rendering.
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//
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// If you want to adjust the position of the text, these functions are useful:
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//
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// * text.BoundString: the rendered bounds of the given text.
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// * golang.org/x/image/font.Face.Metrics: the metrics of the face.
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//
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// The '\n' newline character puts the following text on the next line.
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// Line height is based on Metrics().Height of the font.
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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 Draw with a same text and a same face at every frame in terms of performance.
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//
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// Be careful that the passed font face is held by this package and is never released.
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// This is a known issue (#498).
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//
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// Draw 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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defer textM.Unlock()
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fx, fy := fixed.I(x), fixed.I(y)
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prevR := rune(-1)
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faceHeight := face.Metrics().Height
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runes := []rune(text)
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glyphImgs := getGlyphImages(face, runes)
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colorm := colormcache.ColorToColorM(clr)
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for i, r := range runes {
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if prevR >= 0 {
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fx += face.Kern(prevR, r)
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}
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if r == '\n' {
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fx = fixed.I(x)
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fy += faceHeight
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prevR = rune(-1)
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continue
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}
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drawGlyph(dst, face, r, glyphImgs[i], fx, fy, colorm)
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fx += glyphAdvance(face, r)
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prevR = r
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}
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}
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// BoundString returns the measured size of a given string using a given font.
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// This method will return the exact size in pixels that a string drawn by Draw will be.
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// The bound's origin point indicates the dot (period) position.
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// This means that if the text consists of one character '.', this dot is rendered at (0, 0).
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//
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// This is very similar to golang.org/x/image/font's BoundString,
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// but this BoundString calculates the actual rendered area considering multiple lines and space characters.
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//
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// face is the font for text rendering.
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// text is the string that's being measured.
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//
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// Be careful that the passed font face is held by this package and is never released.
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// This is a known issue (#498).
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//
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// BoundString is concurrent-safe.
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func BoundString(face font.Face, text string) image.Rectangle {
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textM.Lock()
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defer textM.Unlock()
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m := face.Metrics()
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faceHeight := m.Height
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fx, fy := fixed.I(0), fixed.I(0)
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prevR := rune(-1)
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var bounds fixed.Rectangle26_6
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for _, r := range []rune(text) {
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if prevR >= 0 {
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fx += face.Kern(prevR, r)
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}
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if r == '\n' {
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fx = fixed.I(0)
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fy += faceHeight
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prevR = rune(-1)
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continue
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}
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bp := getGlyphBounds(face, r)
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b := *bp
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b.Min.X += fx
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b.Max.X += fx
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b.Min.Y += fy
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b.Max.Y += fy
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bounds = bounds.Union(b)
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fx += glyphAdvance(face, r)
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prevR = r
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}
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return image.Rect(
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int(math.Floor(fixed26_6ToFloat64(bounds.Min.X))),
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int(math.Floor(fixed26_6ToFloat64(bounds.Min.Y))),
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int(math.Ceil(fixed26_6ToFloat64(bounds.Max.X))),
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int(math.Ceil(fixed26_6ToFloat64(bounds.Max.Y))),
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)
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}
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