Example #1
0
// GetStringBounds returns the approximate pixel bounds of the string s at x, y.
// The the left edge of the em square of the first character of s
// and the baseline intersect at 0, 0 in the returned coordinates.
// Therefore the top and left coordinates may well be negative.
func (gc *GraphicContext) GetStringBounds(s string) (left, top, right, bottom float64) {
	f, err := gc.loadCurrentFont()
	if err != nil {
		log.Println(err)
		return 0, 0, 0, 0
	}
	top, left, bottom, right = 10e6, 10e6, -10e6, -10e6
	cursor := 0.0
	prev, hasPrev := truetype.Index(0), false
	for _, rune := range s {
		index := f.Index(rune)
		if hasPrev {
			cursor += fUnitsToFloat64(f.Kern(fixed.Int26_6(gc.Current.Scale), prev, index))
		}
		if err := gc.glyphBuf.Load(gc.Current.Font, fixed.Int26_6(gc.Current.Scale), index, font.HintingNone); err != nil {
			log.Println(err)
			return 0, 0, 0, 0
		}
		e0 := 0
		for _, e1 := range gc.glyphBuf.Ends {
			ps := gc.glyphBuf.Points[e0:e1]
			for _, p := range ps {
				x, y := pointToF64Point(p)
				top = math.Min(top, y)
				bottom = math.Max(bottom, y)
				left = math.Min(left, x+cursor)
				right = math.Max(right, x+cursor)
			}
		}
		cursor += fUnitsToFloat64(f.HMetric(fixed.Int26_6(gc.Current.Scale), index).AdvanceWidth)
		prev, hasPrev = index, true
	}
	return left, top, right, bottom
}
Example #2
0
// 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 fixed.Point26_6 and can therefore represent sub-pixel positions.
func (c *Context) DrawString(s string, p fixed.Point26_6) (fixed.Point26_6, error) {
	if c.f == nil {
		return fixed.Point26_6{}, errors.New("freetype: DrawText called with a nil font")
	}
	prev, hasPrev := truetype.Index(0), false
	for _, rune := range s {
		index := c.f.Index(rune)
		if hasPrev {
			kern := c.f.Kern(c.scale, prev, index)
			if c.hinting != font.HintingNone {
				kern = (kern + 32) &^ 63
			}
			p.X += kern
		}
		advanceWidth, mask, offset, err := c.glyph(index, p)
		if err != nil {
			return fixed.Point26_6{}, err
		}
		p.X += advanceWidth
		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
}
Example #3
0
// CreateStringPath creates a path from the string s at x, y, and returns the string width.
// The text is placed so that the left edge of the em square of the first character of s
// and the baseline intersect at x, y. 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.
func (gc *GraphicContext) CreateStringPath(s string, x, y float64) float64 {
	f, err := gc.loadCurrentFont()
	if err != nil {
		log.Println(err)
		return 0.0
	}
	startx := x
	prev, hasPrev := truetype.Index(0), false
	for _, rune := range s {
		index := f.Index(rune)
		if hasPrev {
			x += fUnitsToFloat64(f.Kern(fixed.Int26_6(gc.Current.Scale), prev, index))
		}
		err := gc.drawGlyph(index, x, y)
		if err != nil {
			log.Println(err)
			return startx - x
		}
		x += fUnitsToFloat64(f.HMetric(fixed.Int26_6(gc.Current.Scale), index).AdvanceWidth)
		prev, hasPrev = index, true
	}
	return x - startx
}