Golang Point.X方法代碼示例

// DrawString draws s at p and returns p advanced by the text extent. The text
// is placed so that the left edge of the em square of the first character of s
// and the baseline intersect at p. The majority of the affected pixels will be
// above and to the right of the point, but some may be below or to the left.
// For example, drawing a string that starts with a 'J' in an italic font may
// affect pixels below and left of the point.
// p is a raster.Point and can therefore represent sub-pixel positions.
func (c *Context) DrawString(s string, p raster.Point) (raster.Point, error) {
	if c.font == nil {
		return raster.Point{}, errors.New("freetype: DrawText called with a nil font")
	}
	prev, hasPrev := truetype.Index(0), false
	for _, rune := range s {
		index := c.font.Index(rune)
		if hasPrev {
			p.X += raster.Fix32(c.font.Kerning(c.scale, prev, index)) << 2
		}
		mask, offset, err := c.glyph(index, p)
		if err != nil {
			return raster.Point{}, err
		}
		p.X += raster.Fix32(c.font.HMetric(c.scale, index).AdvanceWidth) << 2
		glyphRect := mask.Bounds().Add(offset)
		dr := c.clip.Intersect(glyphRect)
		if !dr.Empty() {
			mp := image.Point{0, dr.Min.Y - glyphRect.Min.Y}
			draw.DrawMask(c.dst, dr, c.src, image.ZP, mask, mp, draw.Over)
		}
		prev, hasPrev = index, true
	}
	return p, nil
}

// Render draws rune r front the specified font at the specified dpi and scale.  It returns a
// grayscale image that is just large enough to contain the rune.
func Render(font *truetype.Font, r rune, dpi, scale float64) (*image.Gray, error) {
	glyph := truetype.NewGlyphBuf()
	index := font.Index(r)
	glyph.Load(font, font.FUnitsPerEm(), index, truetype.FullHinting)
	ctx := freetype.NewContext()
	boxer := makeBoundingBoxer()
	ctx.SetSrc(image.NewUniform(color.White))
	ctx.SetDst(boxer)
	ctx.SetClip(boxer.largeBounds)
	ctx.SetFontSize(250)
	ctx.SetDPI(dpi)
	ctx.SetFont(font)
	if err := glyph.Load(font, font.FUnitsPerEm(), font.Index(r), truetype.FullHinting); err != nil {
		return nil, fmt.Errorf("Unable to load glyph: %v\n", err)
	}
	var rp raster.Point
	rp.X = ctx.PointToFix32(0)
	rp.Y = ctx.PointToFix32(100)
	ctx.DrawString(string(r), rp)
	boxer.complete()

	g := gift.New(
		gift.Resize(int(float64(boxer.Bounds().Dx())*scale+0.5), int(float64(boxer.Bounds().Dy())*scale+0.5), gift.CubicResampling),
	)
	dst := image.NewGray(g.Bounds(boxer.Bounds()))
	g.Draw(dst, boxer)
	return dst, nil
}

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

	var p raster.Point
	prev, hasPrev := truetype.Index(0), false
	for _, rune := range s {
		index := ig.font.Index(rune)
		if hasPrev {
			p.X += c.FUnitToFix32(int(ig.font.Kerning(prev, index)))
		}
		p.X += c.FUnitToFix32(int(ig.font.HMetric(index).AdvanceWidth))
		prev, hasPrev = index, true
	}
	return int((p.X + 127) / 256)
}

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)
	scale := int32(fontsize * dpi * (64.0 / 72.0))
	var p raster.Point
	prev, hasPrev := truetype.Index(0), false
	for _, rune := range s {
		index := ig.font.Index(rune)
		if hasPrev {
			p.X += raster.Fix32(ig.font.Kerning(scale, prev, index)) << 2
		}
		p.X += raster.Fix32(ig.font.HMetric(scale, index).AdvanceWidth) << 2
		prev, hasPrev = index, true
	}
	return int((p.X + 127) / 256)
}