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freetype
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freetype: make the point an argument to DrawString, not part of the 

context state. Also rename DrawText to DrawString.

R=r
CC=golang-dev
http://codereview.appspot.com/2208041
This commit is contained in:
Nigel Tao 2010-09-15 14:35:22 +10:00
parent 06369b10f7
commit eda48ef1c3
2 changed files with 14 additions and 22 deletions
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3
example/freetype/main.go
View File

@ -104,8 +104,7 @@ func main() {
// Draw the text.
pt := freetype.Pt(10, 10+c.FUnitToPixelRU(font.UnitsPerEm()))
for _, s := range text {
c.SetPoint(pt)
err = c.DrawText(s)
_, err = c.DrawString(s, pt)
if err != nil {
log.Stderr(err)
return

33
freetype/freetype.go
View File

@ -54,8 +54,6 @@ type Context struct {
r *raster.Rasterizer
font *truetype.Font
glyphBuf *truetype.GlyphBuf
// pt is the location where drawing starts.
pt raster.Point
// clip is the clip rectangle for drawing.
clip image.Rectangle
// dst and src are the destination and source images for drawing.
@ -209,27 +207,28 @@ func (c *Context) glyph(glyph truetype.Index, p raster.Point) (*image.Alpha, ima
return mask, offset.Add(image.Point{ix, iy}), nil
}
// DrawText draws s at the current point and then advances the point. The text
// 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 the point. 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 (c *Context) DrawText(s string) os.Error {
// 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, os.Error) {
if c.font == nil {
return os.NewError("freetype: DrawText called with a nil font")
return raster.Point{}, os.NewError("freetype: DrawText called with a nil font")
}
prev, hasPrev := truetype.Index(0), false
for _, rune := range s {
index := c.font.Index(rune)
if hasPrev {
c.pt.X += c.FUnitToFix32(int(c.font.Kerning(prev, index)))
p.X += c.FUnitToFix32(int(c.font.Kerning(prev, index)))
}
mask, offset, err := c.glyph(index, c.pt)
mask, offset, err := c.glyph(index, p)
if err != nil {
return err
return raster.Point{}, err
}
c.pt.X += c.FUnitToFix32(int(c.font.HMetric(index).AdvanceWidth))
p.X += c.FUnitToFix32(int(c.font.HMetric(index).AdvanceWidth))
glyphRect := mask.Bounds().Add(offset)
dr := c.clip.Intersect(glyphRect)
if !dr.Empty() {
@ -238,7 +237,7 @@ func (c *Context) DrawText(s string) os.Error {
}
prev, hasPrev = index, true
}
return nil
return p, nil
}
// recalc recalculates scale and bounds values from the font size, screen
@ -303,12 +302,6 @@ func (c *Context) SetSrc(src image.Image) {
c.src = src
}
// SetPoint sets the point where DrawText will next draw text.
// pt is a raster.Point and can therefore represent sub-pixel positions.
func (c *Context) SetPoint(pt raster.Point) {
c.pt = pt
}
// SetClip sets the clip rectangle for drawing.
func (c *Context) SetClip(clip image.Rectangle) {
c.clip = clip