draw2d/draw2dbase/text.go

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2016-10-23 02:49:44 +00:00
package draw2dbase
import "github.com/llgcode/draw2d"
var glyphCache map[string]map[rune]*glyph
func init() {
glyphCache = make(map[string]map[rune]*glyph)
}
// FillGlyph copies a glyph from the cache, copies it to the gc, and fills it
func FillGlyph(gc draw2d.GraphicContext, x, y float64, fontName string, chr rune) float64 {
g := fetchGlyph(gc, fontName, chr)
gc.Save()
gc.BeginPath()
gc.Translate(x, y)
gc.Fill(g.Path)
gc.Restore()
return g.Width
}
// StrokeGlyph fetches a glyph from the cache, copies it to the gc, and strokes it
func StrokeGlyph(gc draw2d.GraphicContext, x, y float64, fontName string, chr rune) float64 {
g := fetchGlyph(gc, fontName, chr)
gc.Save()
gc.BeginPath()
gc.Translate(x, y)
gc.Stroke(g.Path)
gc.Restore()
return g.Width
}
// fetchGlyph fetches a glyph from the cache, calling renderGlyph first if it doesn't already exist
func fetchGlyph(gc draw2d.GraphicContext, fontName string, chr rune) *glyph {
if glyphCache[fontName] == nil {
glyphCache[fontName] = make(map[rune]*glyph, 60)
}
if glyphCache[fontName][chr] == nil {
glyphCache[fontName][chr] = renderGlyph(gc, fontName, chr)
}
return glyphCache[fontName][chr].Copy()
}
// renderGlyph renders a Glyph then caches and returns it
func renderGlyph(gc draw2d.GraphicContext, fontName string, chr rune) *glyph {
gc.Save()
defer gc.Restore()
gc.BeginPath()
width := gc.CreateStringPath(string(chr), 0, 0)
path := gc.GetPath()
return &glyph{
Path: &path,
Width: width,
}
}
// glyph represents a rune which has been converted to a Path and width
type glyph struct {
// Path represents a glyph, it is always at (0, 0)
Path *draw2d.Path
// Width of the glyph
Width float64
}
func (g *glyph) Copy() *glyph {
return &glyph{
Path: g.Path.Copy(),
Width: g.Width,
}
}