func (tr MatrixTransform) TransformRasterPoint(points ...*raster.Point) {
for _, point := range points {
x := float64(point.X) / 256
y := float64(point.Y) / 256
point.X = raster.Fix32((x*tr[0] + y*tr[2] + tr[4]) * 256)
point.Y = raster.Fix32((x*tr[1] + y*tr[3] + tr[5]) * 256)
}
}
func (vertexAdder *VertexAdder) Vertex(x, y float64) {
switch vertexAdder.command {
case VertexStartCommand:
vertexAdder.adder.Start(raster.Point{raster.Fix32(x * 256), raster.Fix32(y * 256)})
default:
vertexAdder.adder.Add1(raster.Point{raster.Fix32(x * 256), raster.Fix32(y * 256)})
}
vertexAdder.command = VertexNoCommand
}
func (pathAdder *PathAdder) Convert(paths ...*PathStorage) {
for _, path := range paths {
j := 0
for _, cmd := range path.commands {
switch cmd {
case MoveTo:
pathAdder.firstPoint = raster.Point{raster.Fix32(path.vertices[j] * 256), raster.Fix32(path.vertices[j+1] * 256)}
pathAdder.adder.Start(pathAdder.firstPoint)
j += 2
case LineTo:
pathAdder.adder.Add1(raster.Point{raster.Fix32(path.vertices[j] * 256), raster.Fix32(path.vertices[j+1] * 256)})
j += 2
case QuadCurveTo:
pathAdder.adder.Add2(raster.Point{raster.Fix32(path.vertices[j] * 256), raster.Fix32(path.vertices[j+1] * 256)}, raster.Point{raster.Fix32(path.vertices[j+2] * 256), raster.Fix32(path.vertices[j+3] * 256)})
j += 4
case CubicCurveTo:
pathAdder.adder.Add3(raster.Point{raster.Fix32(path.vertices[j] * 256), raster.Fix32(path.vertices[j+1] * 256)}, raster.Point{raster.Fix32(path.vertices[j+2] * 256), raster.Fix32(path.vertices[j+3] * 256)}, raster.Point{raster.Fix32(path.vertices[j+4] * 256), raster.Fix32(path.vertices[j+5] * 256)})
j += 6
case ArcTo:
lastPoint := arcAdder(pathAdder.adder, path.vertices[j], path.vertices[j+1], path.vertices[j+2], path.vertices[j+3], path.vertices[j+4], path.vertices[j+5], pathAdder.ApproximationScale)
pathAdder.adder.Add1(lastPoint)
j += 6
case Close:
pathAdder.adder.Add1(pathAdder.firstPoint)
}
}
}
}
// 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 {
kern := raster.Fix32(c.font.Kerning(c.scale, prev, index)) << 2
if c.hinting != NoHinting {
kern = (kern + 128) &^ 255
}
p.X += kern
}
advanceWidth, mask, offset, err := c.glyph(index, p)
if err != nil {
return raster.Point{}, 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
}
// rasterize returns the advance width, glyph mask and integer-pixel offset
// to render the given glyph at the given sub-pixel offsets.
// The 24.8 fixed point arguments fx and fy must be in the range [0, 1).
func (c *Context) rasterize(glyph truetype.Index, fx, fy raster.Fix32) (
raster.Fix32, *image.Alpha, image.Point, error) {
if err := c.glyphBuf.Load(c.font, c.scale, glyph, truetype.Hinting(c.hinting)); err != nil {
return 0, nil, image.Point{}, err
}
// Calculate the integer-pixel bounds for the glyph.
xmin := int(fx+raster.Fix32(c.glyphBuf.B.XMin<<2)) >> 8
ymin := int(fy-raster.Fix32(c.glyphBuf.B.YMax<<2)) >> 8
xmax := int(fx+raster.Fix32(c.glyphBuf.B.XMax<<2)+0xff) >> 8
ymax := int(fy-raster.Fix32(c.glyphBuf.B.YMin<<2)+0xff) >> 8
if xmin > xmax || ymin > ymax {
return 0, nil, image.Point{}, errors.New("freetype: negative sized glyph")
}
// A TrueType's glyph's nodes can have negative co-ordinates, but the
// rasterizer clips anything left of x=0 or above y=0. xmin and ymin
// are the pixel offsets, based on the font's FUnit metrics, that let
// a negative co-ordinate in TrueType space be non-negative in
// rasterizer space. xmin and ymin are typically <= 0.
fx += raster.Fix32(-xmin << 8)
fy += raster.Fix32(-ymin << 8)
// Rasterize the glyph's vectors.
c.r.Clear()
e0 := 0
for _, e1 := range c.glyphBuf.End {
c.drawContour(c.glyphBuf.Point[e0:e1], fx, fy)
e0 = e1
}
a := image.NewAlpha(image.Rect(0, 0, xmax-xmin, ymax-ymin))
c.r.Rasterize(raster.NewAlphaSrcPainter(a))
return raster.Fix32(c.glyphBuf.AdvanceWidth << 2), a, image.Point{xmin, ymin}, nil
}
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)
}
func arcAdder(adder raster.Adder, x, y, rx, ry, start, angle, scale float64) raster.Point {
end := start + angle
clockWise := true
if angle < 0 {
clockWise = false
}
ra := (math.Abs(rx) + math.Abs(ry)) / 2
da := math.Acos(ra/(ra+0.125/scale)) * 2
//normalize
if !clockWise {
da = -da
}
angle = start + da
var curX, curY float64
for {
if (angle < end-da/4) != clockWise {
curX = x + math.Cos(end)*rx
curY = y + math.Sin(end)*ry
return raster.Point{raster.Fix32(curX * 256), raster.Fix32(curY * 256)}
}
curX = x + math.Cos(angle)*rx
curY = y + math.Sin(angle)*ry
angle += da
adder.Add1(raster.Point{raster.Fix32(curX * 256), raster.Fix32(curY * 256)})
}
return raster.Point{raster.Fix32(curX * 256), raster.Fix32(curY * 256)}
}
// drawContour draws the given closed contour with the given offset.
func (c *Context) drawContour(ps []truetype.Point, dx, dy raster.Fix32) {
if len(ps) == 0 {
return
}
// The low bit of each point's Flags value is whether the point is on the
// curve. Truetype fonts only have quadratic Bézier curves, not cubics.
// Thus, two consecutive off-curve points imply an on-curve point in the
// middle of those two.
//
// See http://chanae.walon.org/pub/ttf/ttf_glyphs.htm for more details.
// ps[0] is a truetype.Point measured in FUnits and positive Y going
// upwards. start is the same thing measured in fixed point units and
// positive Y going downwards, and offset by (dx, dy).
start := raster.Point{
X: dx + raster.Fix32(ps[0].X<<2),
Y: dy - raster.Fix32(ps[0].Y<<2),
}
others := []truetype.Point(nil)
if ps[0].Flags&0x01 != 0 {
others = ps[1:]
} else {
last := raster.Point{
X: dx + raster.Fix32(ps[len(ps)-1].X<<2),
Y: dy - raster.Fix32(ps[len(ps)-1].Y<<2),
}
if ps[len(ps)-1].Flags&0x01 != 0 {
start = last
others = ps[:len(ps)-1]
} else {
start = raster.Point{
X: (start.X + last.X) / 2,
Y: (start.Y + last.Y) / 2,
}
others = ps
}
}
c.r.Start(start)
q0, on0 := start, true
for _, p := range others {
q := raster.Point{
X: dx + raster.Fix32(p.X<<2),
Y: dy - raster.Fix32(p.Y<<2),
}
on := p.Flags&0x01 != 0
if on {
if on0 {
c.r.Add1(q)
} else {
c.r.Add2(q0, q)
}
} else {
if on0 {
// No-op.
} else {
mid := raster.Point{
X: (q0.X + q.X) / 2,
Y: (q0.Y + q.Y) / 2,
}
c.r.Add2(q0, mid)
}
}
q0, on0 = q, on
}
// Close the curve.
if on0 {
c.r.Add1(start)
} else {
c.r.Add2(q0, start)
}
}
// PointToFix32 converts the given number of points (as in ``a 12 point font'')
// into fixed point units.
func (c *Context) PointToFix32(x float64) raster.Fix32 {
return raster.Fix32(x * float64(c.dpi) * (256.0 / 72.0))
}
// Pt converts from a co-ordinate pair measured in pixels to a raster.Point
// co-ordinate pair measured in raster.Fix32 units.
func Pt(x, y int) raster.Point {
return raster.Point{
X: raster.Fix32(x << 8),
Y: raster.Fix32(y << 8),
}
}
