text/v2: improve the performance with GoXFace

[hajimehoshi]

Operating System

• Windows
• macOS
• Linux
• FreeBSD
• OpenBSD
• Android
• iOS
• Nintendo Switch
• PlayStation 5
• Xbox
• Web Browsers

What feature would you like to be added?

For example, run this program on browsers

package main

import (
	"fmt"
	"math/rand/v2"

	"github.com/hajimehoshi/bitmapfont/v3"

	"github.com/hajimehoshi/ebiten/v2"
	"github.com/hajimehoshi/ebiten/v2/ebitenutil"
	"github.com/hajimehoshi/ebiten/v2/text/v2"
)

const (
	screenWidth  = 640
	screenHeight = 480
	lineHeight   = 12
)

type Game struct {
	face text.Face
	text string
}

func (g *Game) Update() error {
	if g.face == nil {
		g.face = text.NewGoXFace(bitmapfont.Face)
	}
	if g.text == "" {
		const alphabets = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
		xNum := screenWidth / 6
		yNum := (screenHeight / lineHeight) - 1
		for j := 0; j < yNum; j++ {
			for i := 0; i < xNum; i++ {
				g.text += string(alphabets[rand.IntN(len(alphabets))])
			}
			g.text += "\n"
		}
	}
	return nil
}

func (g *Game) Draw(screen *ebiten.Image) {
	ebitenutil.DebugPrint(screen, fmt.Sprintf("FPS: %0.2f, TPS: %0.2f", ebiten.ActualFPS(), ebiten.ActualTPS()))
	op := &text.DrawOptions{}
	op.GeoM.Translate(0, lineHeight)
	op.LineSpacing = 12
	text.Draw(screen, g.text, g.face, op)
}

func (g *Game) Layout(width, height int) (int, int) {
	return screenWidth, screenHeight
}

func main() {
	if err := ebiten.RunGame(&Game{}); err != nil {
		panic(err)
	}
}

This reached 120 FPS on desktop, but doesn't reach 120 FPS on browsers:

                     ..'          hajimehoshi@Hajimes-MacBook-Pro
                 ,xNMM.           -------------------------------
               .OMMMMo            OS: macOS 15.0.1 arm64
               lMM"               Host: MacBook Pro (14-inch, Nov 2023, Three Thunderbolt 4 ports)
     .;loddo:.  .olloddol;.       Kernel: 24.0.0
   cKMMMMMMMMMMNWMMMMMMMMMM0:     Uptime: 1 day, 17 hours, 26 mins
 .KMMMMMMMMMMMMMMMMMMMMMMMWd.     Packages: 143 (brew), 2 (brew-cask)
 XMMMMMMMMMMMMMMMMMMMMMMMX.       Shell: zsh 5.9
;MMMMMMMMMMMMMMMMMMMMMMMM:        Display (Color LCD): 3600x2338 @ 120Hz (as 1800x1169) [Built-in]
:MMMMMMMMMMMMMMMMMMMMMMMM:        DE: Aqua
.MMMMMMMMMMMMMMMMMMMMMMMMX.       WM: Quartz Compositor
 kMMMMMMMMMMMMMMMMMMMMMMMMWd.     WM Theme: Multicolor (Light)
 'XMMMMMMMMMMMMMMMMMMMMMMMMMMk    Font: .AppleSystemUIFont [System], Helvetica [User]
  'XMMMMMMMMMMMMMMMMMMMMMMMMK.    Cursor: Fill - Black, Outline - White (32px)
    kMMMMMMMMMMMMMMMMMMMMMMd      Terminal: Code Helper 1.94.2
     ;KMMMMMMMWXXWMMMMMMMk.       CPU: Apple M3 Pro (12) @ 4.06 GHz
       "cooc*"    "*coo'"         GPU: Apple M3 Pro (18) [Integrated]
                                  Memory: 15.13 GiB / 18.00 GiB (84%)
                                  Swap: 7.16 GiB / 8.00 GiB (89%)
                                  Disk (/): 311.66 GiB / 926.35 GiB (34%) - apfs [Read-only]
                                  Local IP (en0): 192.168.0.10/24 *
                                  Battery: 100% [AC connected]
                                  Power Adapter: 96W USB-C Power Adapter
                                  Locale: en_US.UTF-8

Here is the performance result:

Why is this needed?

No response

[hajimehoshi]

GoTextFace has g.outputCache, while GoXFace doesn't have a counterpart.

[hajimehoshi]

Now the bottleneck is moved from font parsing to rendering, so I'm satisfied.