func drawText(font *truetype.Font, c *freetype.Context, color color.Color, rgba *image.RGBA, text string) (int, int) {
fg := image.NewUniform(color)
bg := image.Transparent
draw.Draw(rgba, rgba.Bounds(), bg, image.ZP, draw.Src)
c.SetFont(font)
c.SetDst(rgba)
c.SetSrc(fg)
c.SetClip(rgba.Bounds())
// height is the fraction of the font that is above the line, 1.0 would mean
// that the font never falls below the line
// TODO: wtf - this is all wrong!
// fix fonts - we can't change the font size easily
height := 1.3
pt := freetype.Pt(0, int(float64(c.PointToFixed(*size)>>8)*height))
adv, _ := c.DrawString(text, pt)
pt.X += adv.X
py := int(float64(pt.Y>>8)/height + 0.01)
return int(pt.X >> 8), py
}
// CenterX returns the Point at which string s will be centered within rect r
// along the X coordinate when passed to c.DrawString. The Y coordinate will be 0.
// Clip is set to r before returning.
func CenterX(c *freetype.Context, s string, r image.Rectangle) (fixed.Point26_6, error) {
w, err := DrawWidth(c, s)
c.SetClip(r)
if err != nil {
return fixed.Point26_6{}, err
}
half := Int26_6(0.5)
xmin := freetype.Pt(r.Min.X, 0)
return freetype.Pt(r.Dx(), 0).Mul(half).Sub(w.Mul(half)).Add(xmin), nil
}
// DrawWidth simulates drawing s using Context c and returns the raster.Point
// where X is the width of the drawn string. The context's src and dst are
// unused, but the font should already be set. Clip is set to an empty Rectangle
// and should be reset afterwards.
func DrawWidth(c *freetype.Context, s string) (fixed.Point26_6, error) {
// nil rectangle is always empty so draw is never called
c.SetClip(image.Rectangle{})
p, err := c.DrawString(s, fixed.Point26_6{}) // 0,0
return p, err
}