Get all glyphs from font

go.mod

@@ -2,14 +2,16 @@ module github.com/bloeys/nterm
 
 go 1.18
 
-require github.com/bloeys/nmage v0.11.12
+require (
+	github.com/bloeys/nmage v0.11.12
+	github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0
+	github.com/veandco/go-sdl2 v0.4.10
+	golang.org/x/image v0.0.0-20220617043117-41969df76e82
+)
 
 require (
 	github.com/bloeys/assimp-go v0.4.2 // indirect
 	github.com/bloeys/gglm v0.3.1 // indirect
 	github.com/go-gl/gl v0.0.0-20211025173605-bda47ffaa784 // indirect
-	github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0 // indirect
 	github.com/inkyblackness/imgui-go/v4 v4.3.0 // indirect
-	github.com/veandco/go-sdl2 v0.4.10 // indirect
-	golang.org/x/image v0.0.0-20220617043117-41969df76e82 // indirect
 )

main.go

@@ -2,15 +2,40 @@ package main
 
 import (
 	"fmt"
+	"image"
+	"image/draw"
+	"image/png"
 	"os"
+	"unicode"
 
 	"github.com/bloeys/nmage/engine"
 	"github.com/bloeys/nmage/input"
 	"github.com/bloeys/nmage/renderer/rend3dgl"
 	nmageimgui "github.com/bloeys/nmage/ui/imgui"
 	"github.com/golang/freetype/truetype"
+	"github.com/veandco/go-sdl2/sdl"
+	"golang.org/x/image/font"
+	"golang.org/x/image/math/fixed"
 )
 
+func main() {
+
+	win, err := engine.CreateOpenGLWindowCentered("nTerm", 1280, 720, engine.WindowFlags_ALLOW_HIGHDPI|engine.WindowFlags_RESIZABLE, rend3dgl.NewRend3DGL())
+	if err != nil {
+		panic("Failed to create window. Err: " + err.Error())
+	}
+
+	engine.SetVSync(true)
+
+	p := &program{
+		shouldRun: true,
+		win:       win,
+		imguiInfo: nmageimgui.NewImGUI(),
+	}
+
+	engine.Run(p)
+}
+
 var _ engine.Game = &program{}
 
 type program struct {
@@ -31,8 +56,39 @@ func (p *program) Init() {
 		panic("Failed to parse font. Err: " + err.Error())
 	}
 
-	face := truetype.NewFace(f, &truetype.Options{Size: 12, DPI: 72})
-	fmt.Println(face.Metrics())
+	size := 40
+	face := truetype.NewFace(f, &truetype.Options{Size: float64(size), DPI: 72})
+	imgFromText("Hello there my friend", size, face, "./text.png")
+	fmt.Println(string(getGlyphs(loadFontRanges(f))))
+}
+
+func imgFromText(text string, textSize int, face font.Face, file string) {
+
+	//Create a white image
+	rgbaDest := image.NewRGBA(image.Rect(0, 0, 640, 480))
+	draw.Draw(rgbaDest, rgbaDest.Bounds(), image.White, image.Point{}, draw.Src)
+
+	//Draw black text on image
+	drawer := &font.Drawer{
+		Dst:  rgbaDest,
+		Src:  image.Black,
+		Face: face,
+	}
+
+	drawer.Dot = fixed.P(0, textSize)
+	drawer.DrawString(text)
+
+	// Save that RGBA image to disk.
+	outFile, err := os.Create(file)
+	if err != nil {
+		panic(err)
+	}
+	defer outFile.Close()
+
+	err = png.Encode(outFile, rgbaDest)
+	if err != nil {
+		panic(err)
+	}
 }
 
 func (p *program) Start() {
@@ -45,7 +101,7 @@ func (p *program) FrameStart() {
 
 func (p *program) Update() {
 
-	if input.IsQuitClicked() {
+	if input.IsQuitClicked() || input.KeyClicked(sdl.K_ESCAPE) {
 		p.shouldRun = false
 	}
 }
@@ -74,20 +130,50 @@ func (p *program) Deinit() {
 
 }
 
-func main() {
-
-	win, err := engine.CreateOpenGLWindowCentered("nTerm", 1280, 720, engine.WindowFlags_ALLOW_HIGHDPI|engine.WindowFlags_RESIZABLE, rend3dgl.NewRend3DGL())
-	if err != nil {
-		panic("Failed to create window. Err: " + err.Error())
+//loadFontRanges returns a list of ranges, each range is: [i][0]<=range<[i][1]
+func loadFontRanges(f *truetype.Font) (ret [][2]rune) {
+	rr := [2]rune{-1, -1}
+	for r := rune(0); r <= unicode.MaxRune; r++ {
+		if privateUseArea(r) {
+			continue
+		}
+		if f.Index(r) == 0 {
+			continue
+		}
+		if rr[1] == r {
+			rr[1] = r + 1
+			continue
+		}
+		if rr[0] != -1 {
+			ret = append(ret, rr)
+		}
+		rr = [2]rune{r, r + 1}
 	}
-
-	engine.SetVSync(true)
-
-	p := &program{
-		shouldRun: true,
-		win:       win,
-		imguiInfo: nmageimgui.NewImGUI(),
+	if rr[0] != -1 {
+		ret = append(ret, rr)
 	}
-
-	engine.Run(p)
+	return ret
+}
+
+func privateUseArea(r rune) bool {
+	return 0xe000 <= r && r <= 0xf8ff ||
+		0xf0000 <= r && r <= 0xffffd ||
+		0x100000 <= r && r <= 0x10fffd
+}
+
+//getGlyphs takes ranges of runes and produces an array of all the runes in these ranges
+func getGlyphs(ranges [][2]rune) []rune {
+
+	out := make([]rune, 0)
+	for _, rr := range ranges {
+
+		temp := make([]rune, 0, rr[1]-rr[0])
+		for r := rr[0]; r < rr[1]; r++ {
+			temp = append(temp, r)
+		}
+
+		out = append(out, temp...)
+	}
+
+	return out
 }