typeset/drawer.go

53 lines
1.2 KiB
Go

package typeset
import "image"
import "unicode"
import "image/draw"
import "image/color"
import "golang.org/x/image/math/fixed"
// Drawer is an extended TypeSetter that is able to draw text. Much like
// TypeSetter, It has no constructor and its zero value can be used safely.
type Drawer struct { TypeSetter }
// Draw draws the drawer's text onto the specified canvas at the given offset.
func (drawer Drawer) Draw (
destination draw.Image,
color color.Color,
offset image.Point,
) (
updatedRegion image.Rectangle,
) {
source := image.NewUniform(color)
drawer.For (func (
index int,
char rune,
position fixed.Point26_6,
) bool {
destinationRectangle,
mask, maskPoint, _, ok := drawer.face.Glyph (
fixed.P (
offset.X + position.X.Round(),
offset.Y + position.Y.Round()),
char)
if !ok || unicode.IsSpace(char) || char == 0 {
return true
}
// FIXME:? clip destination rectangle if we are on the cusp of
// the maximum height.
draw.DrawMask (
destination,
destinationRectangle,
source, image.Point { },
mask, maskPoint,
draw.Over)
updatedRegion = updatedRegion.Union(destinationRectangle)
return true
})
return
}