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Draw* helpers

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This commit is contained in:
Michael Fogleman 2016-02-18 22:11:53 -05:00
parent d2a761c38b
commit 80ced376d0
3 changed files with 116 additions and 62 deletions
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160
context.go
View File

@ -4,6 +4,7 @@ import (
"image" "image"
"image/color" "image/color"
"image/draw" "image/draw"
"math"
"github.com/golang/freetype/raster" "github.com/golang/freetype/raster"
"golang.org/x/image/math/fixed" "golang.org/x/image/math/fixed"
@ -56,28 +57,28 @@ func NewContext(width, height int) *Context {
} }
} }
func (c *Context) Image() image.Image { func (dc *Context) Image() image.Image {
return c.im return dc.im
} }
func (c *Context) Width() int { func (dc *Context) Width() int {
return c.width return dc.width
} }
func (c *Context) Height() int { func (dc *Context) Height() int {
return c.height return dc.height
} }
func (c *Context) WriteToPNG(path string) error { func (dc *Context) WriteToPNG(path string) error {
return writeToPNG(path, c.im) return writeToPNG(path, dc.im)
} }
func (c *Context) Paint() { func (dc *Context) Paint() {
draw.Draw(c.im, c.im.Bounds(), image.NewUniform(c.color), image.ZP, draw.Src) draw.Draw(dc.im, dc.im.Bounds(), image.NewUniform(dc.color), image.ZP, draw.Src)
} }
func (c *Context) SetSourceRGBA(r, g, b, a float64) { func (dc *Context) SetSourceRGBA(r, g, b, a float64) {
c.color = color.NRGBA{ dc.color = color.NRGBA{
uint8(r * 255), uint8(r * 255),
uint8(g * 255), uint8(g * 255),
uint8(b * 255), uint8(b * 255),
@ -85,97 +86,136 @@ func (c *Context) SetSourceRGBA(r, g, b, a float64) {
} }
} }
func (c *Context) SetSourceRGB(r, g, b float64) { func (dc *Context) SetSourceRGB(r, g, b float64) {
c.SetSourceRGBA(r, g, b, 1) dc.SetSourceRGBA(r, g, b, 1)
} }
func (c *Context) SetLineWidth(lineWidth float64) { func (dc *Context) SetLineWidth(lineWidth float64) {
c.lineWidth = lineWidth dc.lineWidth = lineWidth
} }
func (c *Context) SetLineCap(lineCap LineCap) { func (dc *Context) SetLineCap(lineCap LineCap) {
switch lineCap { switch lineCap {
case LineCapButt: case LineCapButt:
c.capper = raster.ButtCapper dc.capper = raster.ButtCapper
case LineCapRound: case LineCapRound:
c.capper = raster.RoundCapper dc.capper = raster.RoundCapper
case LineCapSquare: case LineCapSquare:
c.capper = raster.SquareCapper dc.capper = raster.SquareCapper
} }
} }
func (c *Context) SetLineJoin(lineJoin LineJoin) { func (dc *Context) SetLineJoin(lineJoin LineJoin) {
switch lineJoin { switch lineJoin {
case LineJoinBevel: case LineJoinBevel:
c.joiner = raster.BevelJoiner dc.joiner = raster.BevelJoiner
case LineJoinRound: case LineJoinRound:
c.joiner = raster.RoundJoiner dc.joiner = raster.RoundJoiner
} }
} }
func (c *Context) SetFillRule(fillRule FillRule) { func (dc *Context) SetFillRule(fillRule FillRule) {
c.fillRule = fillRule dc.fillRule = fillRule
} }
func (c *Context) MoveTo(x, y float64) { func (dc *Context) MoveTo(x, y float64) {
c.start = fp(x, y) dc.start = fp(x, y)
c.path.Start(c.start) dc.path.Start(dc.start)
} }
func (c *Context) LineTo(x, y float64) { func (dc *Context) LineTo(x, y float64) {
if len(c.path) == 0 { if len(dc.path) == 0 {
c.MoveTo(x, y) dc.MoveTo(x, y)
} else { } else {
c.path.Add1(fp(x, y)) dc.path.Add1(fp(x, y))
} }
} }
func (c *Context) QuadraticTo(x1, y1, x2, y2 float64) { func (dc *Context) QuadraticTo(x1, y1, x2, y2 float64) {
if len(c.path) == 0 { if len(dc.path) == 0 {
c.MoveTo(x1, y1) dc.MoveTo(x1, y1)
} else { } else {
c.path.Add2(fp(x1, y1), fp(x2, y2)) dc.path.Add2(fp(x1, y1), fp(x2, y2))
} }
} }
func (c *Context) ClosePath() { func (dc *Context) ClosePath() {
if len(c.path) > 0 { if len(dc.path) > 0 {
c.path.Add1(c.start) dc.path.Add1(dc.start)
} }
} }
func (c *Context) NewPath() { func (dc *Context) NewPath() {
c.path.Clear() dc.path.Clear()
} }
func (c *Context) StrokePreserve() { func (dc *Context) StrokePreserve() {
painter := raster.NewRGBAPainter(c.im) painter := raster.NewRGBAPainter(dc.im)
painter.SetColor(c.color) painter.SetColor(dc.color)
r := raster.NewRasterizer(c.width, c.height) r := raster.NewRasterizer(dc.width, dc.height)
r.UseNonZeroWinding = true r.UseNonZeroWinding = true
r.AddStroke(c.path, fi(c.lineWidth), c.capper, c.joiner) r.AddStroke(dc.path, fi(dc.lineWidth), dc.capper, dc.joiner)
r.Rasterize(painter) r.Rasterize(painter)
} }
func (c *Context) Stroke() { func (dc *Context) Stroke() {
c.StrokePreserve() dc.StrokePreserve()
c.NewPath() dc.NewPath()
} }
func (c *Context) FillPreserve() { func (dc *Context) FillPreserve() {
// make sure the path is closed // make sure the path is closed
path := make(raster.Path, len(c.path)) path := make(raster.Path, len(dc.path))
copy(path, c.path) copy(path, dc.path)
path.Add1(c.start) path.Add1(dc.start)
painter := raster.NewRGBAPainter(c.im) painter := raster.NewRGBAPainter(dc.im)
painter.SetColor(c.color) painter.SetColor(dc.color)
r := raster.NewRasterizer(c.width, c.height) r := raster.NewRasterizer(dc.width, dc.height)
r.UseNonZeroWinding = c.fillRule == FillRuleWinding r.UseNonZeroWinding = dc.fillRule == FillRuleWinding
r.AddPath(path) r.AddPath(path)
r.Rasterize(painter) r.Rasterize(painter)
} }
func (c *Context) Fill() { func (dc *Context) Fill() {
c.FillPreserve() dc.FillPreserve()
c.NewPath() dc.NewPath()
}
func (dc *Context) DrawLine(x1, y1, x2, y2 float64) {
dc.MoveTo(x1, y1)
dc.LineTo(x2, y2)
}
func (dc *Context) DrawEllipseArc(x, y, rx, ry, angle1, angle2 float64) {
const n = 16
for i := 0; i <= n; i++ {
p1 := float64(i+0) / n
p2 := float64(i+1) / n
a1 := angle1 + (angle2-angle1)*p1
a2 := angle1 + (angle2-angle1)*p2
x0 := x + rx*math.Cos(a1)
y0 := y + ry*math.Sin(a1)
x1 := x + rx*math.Cos(a1+(a2-a1)/2)
y1 := y + ry*math.Sin(a1+(a2-a1)/2)
x2 := x + rx*math.Cos(a2)
y2 := y + ry*math.Sin(a2)
cx := 2*x1 - x0/2 - x2/2
cy := 2*y1 - y0/2 - y2/2
if i == 0 {
dc.MoveTo(x0, y0)
}
dc.QuadraticTo(cx, cy, x2, y2)
}
}
func (dc *Context) DrawEllipse(x, y, rx, ry float64) {
dc.DrawEllipseArc(x, y, rx, ry, 0, 2*math.Pi)
}
func (dc *Context) DrawArc(x, y, r, angle1, angle2 float64) {
dc.DrawEllipseArc(x, y, r, r, angle1, angle2)
}
func (dc *Context) DrawCircle(x, y, r float64) {
dc.DrawEllipseArc(x, y, r, r, 0, 2*math.Pi)
} }

16
examples/circle.go Normal file
View File

@ -0,0 +1,16 @@
package main
import "github.com/fogleman/dd"
func main() {
dc := dd.NewContext(1000, 1000)
dc.SetSourceRGB(1, 1, 1)
dc.Paint()
dc.DrawCircle(500, 500, 400)
dc.SetSourceRGBA(0, 0, 0, 0.25)
dc.FillPreserve()
dc.SetSourceRGB(0, 0, 0.5)
dc.SetLineWidth(8)
dc.Stroke()
dc.WriteToPNG("out.png")
}

2
examples/example0.go
View File

@ -15,8 +15,6 @@ func main() {
dc.FillPreserve() dc.FillPreserve()
dc.SetSourceRGB(0, 0, 0) dc.SetSourceRGB(0, 0, 0)
dc.SetLineWidth(8) dc.SetLineWidth(8)
// dc.SetLineCap(dd.LineCapButt)
// dc.SetLineJoin(dd.LineJoinBevel)
dc.Stroke() dc.Stroke()
dc.WriteToPNG("out.png") dc.WriteToPNG("out.png")
} }