Beispiel #1
0
func generateAtlas(font *truetype.Font, scale int32, dpi float64, width, height float32) ([]Vector4, *image.RGBA, []float32) {
	var low rune = 32
	var high rune = 127
	glyphCount := int32(high - low + 1)
	offsets := make([]float32, glyphCount)

	bounds := font.Bounds(scale)
	gw := float32(bounds.XMax - bounds.XMin)
	gh := float32(bounds.YMax - bounds.YMin)
	imageWidth := glh.Pow2(uint32(gw * float32(glyphCount)))
	imageHeight := glh.Pow2(uint32(gh))
	imageBounds := image.Rect(0, 0, int(imageWidth), int(imageHeight))
	sx := float32(2) / width
	sy := float32(2) / height
	w := gw * sx
	h := gh * sy
	img := image.NewRGBA(imageBounds)
	c := freetype.NewContext()
	c.SetDst(img)
	c.SetClip(img.Bounds())
	c.SetSrc(image.White)
	c.SetDPI(dpi)
	c.SetFontSize(float64(scale))
	c.SetFont(font)

	var gi int32
	var gx, gy float32
	verts := make([]Vector4, 0)
	texWidth := float32(img.Bounds().Dx())
	texHeight := float32(img.Bounds().Dy())

	for ch := low; ch <= high; ch++ {
		index := font.Index(ch)
		metric := font.HMetric(scale, index)

		//the offset is used when drawing a string of glyphs - we will advance a glyph's quad by the width of all previous glyphs in the string
		offsets[gi] = float32(metric.AdvanceWidth) * sx

		//draw the glyph into the atlas at the correct location
		pt := freetype.Pt(int(gx), int(gy)+int(c.PointToFix32(float64(scale))>>8))
		c.DrawString(string(ch), pt)

		tx1 := gx / texWidth
		ty1 := gy / texHeight
		tx2 := (gx + gw) / texWidth
		ty2 := (gy + gh) / texHeight

		//the x,y coordinates are the same for each quad; only the texture coordinates (stored in z,w) change.
		//an optimization would be to only store texture coords, but I haven't figured that out yet
		verts = append(verts, Vector4{-1, 1, tx1, ty1},
			Vector4{-1 + (w), 1, tx2, ty1},
			Vector4{-1, 1 - (h), tx1, ty2},
			Vector4{-1 + (w), 1 - (h), tx2, ty2})

		gx += gw
		gi++
	}
	return verts, img, offsets
}
func printRuneInfo(canvas *Canvas, font *truetype.Font, r rune) {
	index := font.Index(r)
	scale := int32(50)
	hmetric := font.HMetric(scale, index)
	vmetric := font.VMetric(scale, index)

	println("Index:", index)
	println("FUnitsPerEm:", font.FUnitsPerEm())
	println("Scale:", scale)
	println("HMetric:", hmetric)
	println("VMetric:", vmetric)
}
Beispiel #3
0
func printGlyph(font *truetype.Font, c rune, resolution int32) {
	var idx = font.Index(c)
	var hm = font.HMetric(resolution, idx)
	var g = truetype.NewGlyphBuf()
	err := g.Load(font, resolution, idx, truetype.NoHinting)
	if err != nil {
		log.Println(err)
		return
	}
	fmt.Printf("'%c' glyph\n", c)
	fmt.Printf("AdvanceWidth:%d LeftSideBearing:%d\n", hm.AdvanceWidth, hm.LeftSideBearing)
	printGlyphCurve(g)

	c1 := 'A'
	i1 := font.Index(c1)
	fmt.Printf("\n'%c', '%c' Kerning:%d\n", c, c1, font.Kerning(resolution, idx, i1))
}
Beispiel #4
0
func ExpectedSize(font *truetype.Font, s string) (int32, int32, error) {

	c := freetype.NewContext()
	c.SetDPI(dpi)
	c.SetFont(font)
	c.SetFontSize(size)

	scale := size / float64(font.FUnitsPerEm())

	prev := font.Index(rune(s[0]))
	width := int32(font.HMetric(font.FUnitsPerEm(), prev).AdvanceWidth)
	for _, char := range s[1:] {
		index := font.Index(char)
		width += int32(font.Kerning(font.FUnitsPerEm(), prev, index) +
			font.HMetric(font.FUnitsPerEm(), index).AdvanceWidth)
		prev = index
	}
	width = int32(float64(width) * scale)

	bounds := font.Bounds(font.FUnitsPerEm())
	height := int32(float64(bounds.YMax-bounds.YMin) * scale)

	return width, height, nil
}