text: Replace MeasureString with BoundString

Fixes #1272

examples/font/main.go

@@ -37,12 +37,13 @@ const (
 	screenHeight = 480
 )
 
+const sampleText = `The quick brown fox jumps over the lazy dog.`
+
 var (
-	sampleText      = `The quick brown fox jumps over the lazy dog.`
 	mplusNormalFont font.Face
 	mplusBigFont    font.Face
+	jaKanjis        = []rune{}
 )
-var jaKanjis = []rune{}
 
 func init() {
 	// table is the list of Japanese Kanji characters in a part of JIS X 0208.

examples/text/main.go

@@ -0,0 +1,107 @@
+// Copyright 2020 The Ebiten 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.
+
+// +build example jsgo
+
+package main
+
+import (
+	"image/color"
+	"log"
+	"math/rand"
+	"time"
+
+	"github.com/golang/freetype/truetype"
+	"golang.org/x/image/font"
+
+	"github.com/hajimehoshi/ebiten"
+	"github.com/hajimehoshi/ebiten/ebitenutil"
+	"github.com/hajimehoshi/ebiten/examples/resources/fonts"
+	"github.com/hajimehoshi/ebiten/text"
+)
+
+const (
+	screenWidth  = 640
+	screenHeight = 480
+)
+
+const sampleText = `The quick brown fox jumps
+over the lazy dog.`
+
+var (
+	mplusNormalFont font.Face
+	mplusBigFont    font.Face
+)
+
+func init() {
+	tt, err := truetype.Parse(fonts.MPlus1pRegular_ttf)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	const dpi = 72
+	mplusNormalFont = truetype.NewFace(tt, &truetype.Options{
+		Size:    24,
+		DPI:     dpi,
+		Hinting: font.HintingFull,
+	})
+	mplusBigFont = truetype.NewFace(tt, &truetype.Options{
+		Size:    32,
+		DPI:     dpi,
+		Hinting: font.HintingFull,
+	})
+}
+
+func init() {
+	rand.Seed(time.Now().UnixNano())
+}
+
+type Game struct {
+	counter        int
+	kanjiText      []rune
+	kanjiTextColor color.RGBA
+}
+
+func (g *Game) Update(screen *ebiten.Image) error {
+	return nil
+}
+
+func (g *Game) Draw(screen *ebiten.Image) {
+	gray := color.RGBA{0x80, 0x80, 0x80, 0xff}
+
+	{
+		const x, y = 20, 40
+		b := text.BoundString(mplusNormalFont, sampleText)
+		ebitenutil.DrawRect(screen, float64(b.Min.X+x), float64(b.Min.Y+y), float64(b.Dx()), float64(b.Dy()), gray)
+		text.Draw(screen, sampleText, mplusNormalFont, x, y, color.White)
+	}
+	{
+		const x, y = 20, 140
+		b := text.BoundString(mplusBigFont, sampleText)
+		ebitenutil.DrawRect(screen, float64(b.Min.X+x), float64(b.Min.Y+y), float64(b.Dx()), float64(b.Dy()), gray)
+		text.Draw(screen, sampleText, mplusBigFont, x, y, color.White)
+	}
+}
+
+func (g *Game) Layout(outsideWidth, outsideHeight int) (int, int) {
+	return screenWidth, screenHeight
+}
+
+func main() {
+	ebiten.SetWindowSize(screenWidth, screenHeight)
+	ebiten.SetWindowTitle("Font (Ebiten Demo)")
+	if err := ebiten.RunGame(&Game{}); err != nil {
+		log.Fatal(err)
+	}
+}

text/text.go

@@ -208,9 +208,8 @@ var textM sync.Mutex
 //
 // If you want to adjust the position of the text, these functions are useful:
 //
+//     * text.BoundString:                     the rendered bounds of the given text.
 //     * golang.org/x/image/font.Face.Metrics: the metrics of the face.
-//     * text.MeasureString:                   the size of the given text.
-//     * golang.org/x/image/font.BoundString:  the bound rectangle of the given text.
 //
 // The '\n' newline character puts the following text on the next line.
 // Line height is based on Metrics().Height of the font.
@@ -253,10 +252,11 @@ func Draw(dst *ebiten.Image, text string, face font.Face, x, y int, clr color.Co
 	}
 }
 
-// MeasureString returns the measured size of a given string using a given font.
+// BoundString returns the measured size of a given string using a given font.
 // This method will return the exact size in pixels that a string drawn by Draw will be.
 //
-// This is very similar to golang.org/x/image/font's MeasureString, but this MeasureString considers multiple lines.
+// This is very similar to golang.org/x/image/font's BoundString,
+// but this BoundString calculates the actual rendered area considering multiple lines and space characters.
 //
 // text is the string that's being measured.
 // face is the font for text rendering.
@@ -264,23 +264,19 @@ func Draw(dst *ebiten.Image, text string, face font.Face, x, y int, clr color.Co
 // Be careful that the passed font face is held by this package and is never released.
 // This is a known issue (#498).
 //
-// MeasureString is concurrent-safe.
-func MeasureString(text string, face font.Face) image.Point {
+// BoundString is concurrent-safe.
+func BoundString(face font.Face, text string) image.Rectangle {
 	textM.Lock()
 	defer textM.Unlock()
 
-	var w, h fixed.Int26_6
-
 	m := face.Metrics()
 	faceHeight := m.Height
-	faceDescent := m.Descent
 
 	fx, fy := fixed.I(0), fixed.I(0)
 	prevR := rune(-1)
 
-	runes := []rune(text)
-
-	for _, r := range runes {
+	var bounds fixed.Rectangle26_6
+	for _, r := range []rune(text) {
 		if prevR >= 0 {
 			fx += face.Kern(prevR, r)
 		}
@@ -291,22 +287,22 @@ func MeasureString(text string, face font.Face) image.Point {
 			continue
 		}
 
+		bp := getGlyphBounds(face, r)
+		b := *bp
+		b.Min.X += fx
+		b.Max.X += fx
+		b.Min.Y += fy
+		b.Max.Y += fy
+		bounds = bounds.Union(b)
+
 		fx += glyphAdvance(face, r)
-
-		if fx > w {
-			w = fx
-		}
-		if (fy + faceHeight) > h {
-			h = fy + faceHeight
-		}
-
 		prevR = r
 	}
 
-	bounds := image.Point{
-		X: int(math.Ceil(fixed26_6ToFloat64(w))),
-		Y: int(math.Ceil(fixed26_6ToFloat64(h + faceDescent))),
-	}
-
-	return bounds
+	return image.Rect(
+		int(math.Floor(fixed26_6ToFloat64(bounds.Min.X))),
+		int(math.Floor(fixed26_6ToFloat64(bounds.Min.Y))),
+		int(math.Ceil(fixed26_6ToFloat64(bounds.Max.X))),
+		int(math.Ceil(fixed26_6ToFloat64(bounds.Max.Y))),
+	)
 }