Golang freetype.NewContext函数代码示例

func (this *Signer) drawStringImage(text string) (image.Image, error) {
	fontBytes, err := ioutil.ReadFile(this.fontPath)
	if err != nil {
		fmt.Println(err)
	}

	font, err := freetype.ParseFont(fontBytes)
	if err != nil {
		fmt.Println(err)
	}

	rgba := image.NewRGBA(image.Rect(0, 0, 900, 900))

	draw.Draw(rgba, rgba.Bounds(), image.Black, image.ZP, draw.Src)
	c := freetype.NewContext()
	c.SetDPI(this.dpi)
	c.SetFontSize(this.fontSize)
	c.SetClip(rgba.Bounds())
	c.SetDst(rgba)
	c.SetSrc(image.White)
	c.SetFont(font)

	pt := freetype.Pt(100, 100+int(c.PointToFixed(this.fontSize)>>8))
	for _, s := range strings.Split(text, "\r\n") {
		_, err = c.DrawString(s, pt)
		pt.Y += c.PointToFixed(12 * 1.5)

	}

	return rgba, nil

}

func NewFontFace(path string, pixels float32, fg, bg color.Color) (fontface *FontFace, err error) {
	var (
		font      *truetype.Font
		fontbytes []byte
		bounds    fixed.Rectangle26_6
		context   *freetype.Context
		points    float32
		dpi       float32 = 96
	)
	if fontbytes, err = ioutil.ReadFile(path); err != nil {
		return
	}
	if font, err = freetype.ParseFont(fontbytes); err != nil {
		return
	}
	points = pixels * 72 / dpi
	bounds = font.Bounds(fixed.I(int(pixels)))
	context = freetype.NewContext()
	context.SetFont(font)
	context.SetFontSize(float64(points))
	context.SetDPI(float64(dpi))
	fontface = &FontFace{
		font:    font,
		charw:   float32(bounds.Max.X-bounds.Min.X) / 64,
		charh:   float32(bounds.Max.Y-bounds.Min.Y) / 64,
		offy:    float32(bounds.Min.Y) / 64,
		fg:      fg,
		bg:      bg,
		context: context,
	}
	return
}

func (a *Annotator) init() error {

	// load the font
	fontBytes, err := resources.Asset(fontfile)
	if err != nil {
		return err
	}

	luxisr, err := freetype.ParseFont(fontBytes)
	if err != nil {
		return err
	}

	// Initialize the context.
	fg := image.White

	a.context = freetype.NewContext()
	a.context.SetDPI(dpi)
	a.context.SetFont(luxisr)
	a.context.SetFontSize(size)

	a.context.SetClip(a.image.Bounds())
	a.context.SetDst(a.image)
	a.context.SetSrc(fg)

	switch hinting {
	default:
		a.context.SetHinting(font.HintingNone)
	case "full":
		a.context.SetHinting(font.HintingFull)
	}

	return nil
}

func (font *Font) updateTexture(texture uint32, text string, width int, height int, size float64, dpi float64, rgba color.Color) (int, int) {
	context := freetype.NewContext()
	context.SetFont(font.ttf)

	img := image.NewRGBA(image.Rect(0, 0, width, height))
	r, g, b, _ := rgba.RGBA()
	draw.Draw(img, img.Bounds(), image.NewUniform(color.RGBA{uint8(r), uint8(g), uint8(b), 0}), image.ZP, draw.Src)

	context.SetDst(img)
	context.SetClip(img.Bounds())
	context.SetSrc(image.NewUniform(rgba))
	context.SetFontSize(size)
	context.SetDPI(dpi)
	pixelBounds, _ := context.DrawString(text, freetype.Pt(0, height/2))

	gl.ActiveTexture(gl.TEXTURE0)
	gl.BindTexture(gl.TEXTURE_2D, texture)

	gl.TexSubImage2D(
		gl.TEXTURE_2D,
		0,
		0,
		0,
		int32(img.Rect.Size().X),
		int32(img.Rect.Size().Y),
		gl.RGBA,
		gl.UNSIGNED_BYTE,
		gl.Ptr(img.Pix))

	return int26_6Ceiling(pixelBounds.X + 0x3f), int26_6Ceiling(pixelBounds.Y + 0x3f)
}

func NewFontFace(path string, size float64, fg, bg color.Color) (fontface *FontFace, err error) {
	var (
		font      *truetype.Font
		fontbytes []byte
		bounds    truetype.Bounds
		context   *freetype.Context
		scale     float32
	)
	if fontbytes, err = ioutil.ReadFile(path); err != nil {
		return
	}
	if font, err = freetype.ParseFont(fontbytes); err != nil {
		return
	}
	bounds = font.Bounds(1)
	fmt.Printf("bounds %v\n", bounds)
	context = freetype.NewContext()
	context.SetFont(font)
	context.SetFontSize(size)
	context.SetDPI(72)
	scale = float32(context.PointToFixed(size) / 64)
	fontface = &FontFace{
		font:    font,
		charw:   scale * float32(bounds.XMax-bounds.XMin),
		charh:   scale * float32(bounds.YMax-bounds.YMin),
		fg:      fg,
		bg:      bg,
		context: context,
	}
	return
}

func (f *Font) Render(text string) *Texture {
	width, height, yBearing := f.TextDimensions(text)
	font := f.ttf
	size := f.Size

	// Colors
	fg := image.NewUniform(color.NRGBA{f.FG.R, f.FG.G, f.FG.B, f.FG.A})
	bg := image.NewUniform(color.NRGBA{f.BG.R, f.BG.G, f.BG.B, f.BG.A})

	// Create the font context
	c := freetype.NewContext()

	nrgba := image.NewNRGBA(image.Rect(0, 0, width, height))
	draw.Draw(nrgba, nrgba.Bounds(), bg, image.ZP, draw.Src)

	c.SetDPI(dpi)
	c.SetFont(font)
	c.SetFontSize(size)
	c.SetClip(nrgba.Bounds())
	c.SetDst(nrgba)
	c.SetSrc(fg)

	// Draw the text.
	pt := freetype.Pt(0, int(yBearing))
	_, err := c.DrawString(text, pt)
	if err != nil {
		log.Println(err)
		return nil
	}

	// Create texture
	imObj := &ImageObject{nrgba}
	return NewTexture(imObj)

}

func Example() {
	// As usual in examples, this ignores all errors. Don't do this in your program.

	// setup and find start point for centering
	s := "Hello, World!"
	size := image.Rect(0, 0, 120, 20)
	dst := image.NewRGBA(size)
	c := freetype.NewContext()
	c.SetFont(font)
	c.SetFontSize(14.0)
	c.SetSrc(image.NewUniform(color.Black))
	c.SetDst(dst)
	start, _ := fontutil.CenterX(c, s, size) // CenterX calls c.SetClip(size)

	// perform draw at start.X + y 16
	c.DrawString(s, start.Add(freetype.Pt(0, 16)))

	// write the image out to a file
	// out, _ := os.Create("helloworld.png")
	// defer out.Close()

	// write image to hash for testing purposes
	out := fnv.New64()
	_ = png.Encode(out, dst)
	fmt.Printf("Hash of compressed image: %x", out.Sum64())
	// Output: Hash of compressed image: fa83a1b8d8abf5f2
}

func makeImage(req *http.Request, caption, font string, pt, size, border, scale int, f func(x, y int) uint32) *image.RGBA {
	d := (size + 2*border) * scale
	csize := 0
	if caption != "" {
		if pt == 0 {
			pt = 11
		}
		csize = pt * 2
	}
	c := image.NewRGBA(image.Rect(0, 0, d, d+csize))

	// white
	u := &image.Uniform{C: color.White}
	draw.Draw(c, c.Bounds(), u, image.ZP, draw.Src)

	for y := 0; y < size; y++ {
		for x := 0; x < size; x++ {
			r := image.Rect((x+border)*scale, (y+border)*scale, (x+border+1)*scale, (y+border+1)*scale)
			rgba := f(x, y)
			u.C = color.RGBA{byte(rgba >> 24), byte(rgba >> 16), byte(rgba >> 8), byte(rgba)}
			draw.Draw(c, r, u, image.ZP, draw.Src)
		}
	}

	if csize != 0 {
		if font == "" {
			font = "data/luxisr.ttf"
		}
		ctxt := fs.NewContext(req)
		dat, _, err := ctxt.Read(font)
		if err != nil {
			panic(err)
		}
		tfont, err := freetype.ParseFont(dat)
		if err != nil {
			panic(err)
		}
		ft := freetype.NewContext()
		ft.SetDst(c)
		ft.SetDPI(100)
		ft.SetFont(tfont)
		ft.SetFontSize(float64(pt))
		ft.SetSrc(image.NewUniform(color.Black))
		ft.SetClip(image.Rect(0, 0, 0, 0))
		wid, err := ft.DrawString(caption, freetype.Pt(0, 0))
		if err != nil {
			panic(err)
		}
		p := freetype.Pt(d, d+3*pt/2)
		p.X -= wid.X
		p.X /= 2
		ft.SetClip(c.Bounds())
		ft.DrawString(caption, p)
	}

	return c
}

// initLayout constructs two masks for drawing the battery and the remaining
// energy as well as sets the pixel bounds for drawing energy capacity.  the
// masks allow for simplified space-fills and reduced chance of pixel gaps.
func (app *App) initLayout() {
	var zeropt image.Point

	rectOutTop := image.Rectangle{Min: app.Layout.battRect.Min, Max: app.Layout.battRect.Min.Add(image.Point{2, 2})}
	rectOutBottom := rectOutTop.Add(image.Point{Y: app.Layout.battRect.Size().Y - rectOutTop.Size().Y})
	capRect := image.Rectangle{
		Min: image.Point{X: rectOutTop.Min.X, Y: rectOutTop.Max.Y},
		Max: image.Point{X: rectOutBottom.Max.X, Y: rectOutBottom.Min.Y},
	}
	bodyRect := app.Layout.battRect
	bodyRect.Min.X = capRect.Max.X

	// energy will be drawn under the battery shell.  The only place where it
	// is not safe to draw energy is outside the battery on the positive end.
	energyMask := image.NewAlpha(app.Layout.battRect)
	draw.Draw(energyMask, app.Layout.battRect, opaque, zeropt, draw.Over)
	draw.Draw(energyMask, rectOutTop, transparent, zeropt, draw.Src)
	draw.Draw(energyMask, rectOutBottom, transparent, zeropt, draw.Src)
	app.maskEnergy = energyMask

	// the body uses the same mask as the energy with additional transparency
	// inside the battery's shell.  the mask construction is complex because
	// area inside the cap may be exposed.
	bodyMask := image.NewAlpha(app.Layout.battRect)
	draw.Draw(bodyMask, app.Layout.battRect, energyMask, app.Layout.battRect.Min, draw.Over)
	bodyMaskRect := shrinkRect(bodyRect, app.Layout.thickness)
	draw.Draw(bodyMask, bodyMaskRect, transparent, zeropt, draw.Src)
	capMaskRect := shrinkRect(capRect, app.Layout.thickness)
	capMaskRect.Max.X += 2 * app.Layout.thickness
	draw.Draw(bodyMask, capMaskRect, transparent, zeropt, draw.Src)
	app.maskBattery = bodyMask

	// create a freetype.Context to render text.  each time the context is used
	// it must have its SetDst method called.
	app.tt = freetype.NewContext()
	app.tt.SetSrc(black)
	app.tt.SetClip(app.Layout.textRect)
	app.tt.SetDPI(app.Layout.DPI)
	app.tt.SetFont(app.Layout.font)
	app.tt.SetFontSize(app.Layout.fontSize)
	ttopt := &truetype.Options{
		Size: app.Layout.fontSize,
		DPI:  app.Layout.DPI,
	}
	ttface := truetype.NewFace(app.Layout.font, ttopt)
	app.font = &font.Drawer{
		Src:  black,
		Face: ttface,
	}

	// the rectangle in which energy is drawn needs to account for thickness to
	// make the visible percentage more accurate.  after adjustment reduce the
	// energy rect to account for the account of energy drained.  the energy
	// mask makes computing Y bounds largely irrelevant.
	app.minEnergy = capMaskRect.Min.X
	app.maxEnergy = bodyMaskRect.Max.X
}

func main() {
	fontBytes, err := ioutil.ReadFile("luxisr.ttf")
	if err != nil {
		log.Fatal(err)
	}
	font, err := freetype.ParseFont(fontBytes)
	if err != nil {
		log.Fatal(err)
	}

	fg, bg := image.White, image.Black
	rgba := image.NewRGBA(image.Rect(0, 0, width, height))
	draw.Draw(rgba, rgba.Bounds(), bg, image.ZP, draw.Src)
	c := freetype.NewContext()
	c.SetDPI(dpi)
	c.SetFont(font)
	c.SetFontSize(size)
	c.SetClip(rgba.Bounds())
	c.SetDst(rgba)
	c.SetSrc(fg)
	c.SetHinting(freetype.FullHinting)

	count := 0
	l := NewLife(width, height)
	for {
		if count%10 == 0 {
			count = 0
			pt := freetype.Pt(rand.Intn(width-width/4), height/4+rand.Intn(height-height/4))
			c.DrawString("NOPE", pt)
			for x := 0; x < width; x++ {
				for y := 0; y < height; y++ {
					c := rgba.RGBAAt(x, y)
					l.a.Set(x, y, c.R > 0 || c.B > 0 || c.G > 0)
				}
			}
		}
		count++

		for x := 0; x < width; x++ {
			for y := 0; y < height; y++ {
				var c color.Color = color.Black
				if l.a.Alive(x, y) {
					c = rainbow(y)
				}
				rgba.Set(x, y, c)
			}
		}

		//fmt.Println(l)
		sendImage(rgba)
		l.Step()

		time.Sleep(time.Second / 8)
	}
}

// Write a text inside the image
func WriteText(text string, f *truetype.Font, img *image.Paletted) {
	// Initialize the context.
	fg := image.Black
	c := freetype.NewContext()
	c.SetDPI(72)
	c.SetFont(f)
	c.SetFontSize(64)
	c.SetClip(img.Bounds())
	c.SetDst(img)
	c.SetSrc(fg)
	// Draw the text.
	pt := freetype.Pt(40, 120)
	c.DrawString(text, pt)
}

func (ig *ImageGraphics) TextLen(s string, font chart.Font) int {
	c := freetype.NewContext()
	c.SetDPI(dpi)
	c.SetFont(ig.font)
	fontsize := ig.relFontsizeToPixel(font.Size)
	c.SetFontSize(fontsize)

	// really draw it
	width, err := c.DrawString(s, freetype.Pt(0, 0))
	if err != nil {
		return 10 * len(s) // BUG
	}
	return int(width.X+32)>>6 + 1
}

func MakeTextLine(font_name, text string, width int, r, g, b, a float64) *TextLine {
	var w TextLine
	w.EmbeddedWidget = &BasicWidget{CoreWidget: &w}
	font, ok := basic_fonts[font_name]
	if !ok {
		panic(fmt.Sprintf("Unable to find a font registered as '%s'.", font_name))
	}
	w.font = font
	w.glyph_buf = &truetype.GlyphBuf{}
	w.next_text = text
	w.context = freetype.NewContext()
	w.context.SetDPI(132)
	w.context.SetFontSize(12)
	w.SetColor(r, g, b, a)
	w.Request_dims = Dims{width, 35}
	return &w
}

func (f *Font) RenderNRGBA(text string) *image.NRGBA {
	width, height, yBearing := f.TextDimensions(text)
	font := f.TTF
	size := f.Size

	if size <= 0 {
		panic("Font size cannot be <= 0")
	}

	// Default colors
	if f.FG == nil {
		f.FG = color.NRGBA{0, 0, 0, 0}
	}
	if f.BG == nil {
		f.BG = color.NRGBA{0, 0, 0, 0}
	}

	// Colors
	fg := image.NewUniform(f.FG)
	bg := image.NewUniform(f.BG)

	// Create the font context
	c := freetype.NewContext()

	nrgba := image.NewNRGBA(image.Rect(0, 0, width, height))
	draw.Draw(nrgba, nrgba.Bounds(), bg, image.ZP, draw.Src)

	c.SetDPI(dpi)
	c.SetFont(font)
	c.SetFontSize(size)
	c.SetClip(nrgba.Bounds())
	c.SetDst(nrgba)
	c.SetSrc(fg)

	// Draw the text.
	pt := fixed.P(0, int(yBearing))
	_, err := c.DrawString(text, pt)
	if err != nil {
		log.Println(err)
		return nil
	}

	return nrgba
}

func main() {
	imgcounter := 123
	imgfile, _ := os.Create(fmt.Sprintf("%03d.png", imgcounter))

	defer imgfile.Close()

	img := image.NewNRGBA(image.Rect(0, 0, dx, dy))

	for y := 0; y < dy; y++ {
		for x := 0; x < dx; x++ {
			img.Set(x, y, color.RGBA{uint8(x), uint8(y), 0, 255})
		}
	}

	fontBytes, err := ioutil.ReadFile(fontFile) //读取字体数据
	if err != nil {
		fmt.Println(err)
		return
	}
	font, err := freetype.ParseFont(fontBytes)
	if err != nil {
		fmt.Print(err)
		return
	}
	c := freetype.NewContext()
	c.SetDPI(fontDPI)
	c.SetFont(font)
	c.SetFontSize(fontSize)
	c.SetClip(img.Bounds())
	c.SetDst(img)
	c.SetSrc(image.White)
	pt := freetype.Pt(10, 10+int(c.PointToFixed(fontSize)>>8)) // 字出现的位置

	_, err = c.DrawString("ABCDE", pt)
	if err != nil {
		fmt.Println(err)
		return
	}
	err = png.Encode(imgfile, img)
	if err != nil {
		fmt.Println(err)
	}

}