Golang draw2d.GraphicContext类代码示例

// Main draws "Hello World" and returns the filename. This should only be
// used during testing.
func Main(gc draw2d.GraphicContext, ext string) (string, error) {
	// Draw hello world
	Draw(gc, fmt.Sprintf("Hello World %d dpi", gc.GetDPI()))

	// Return the output filename
	return samples.Output("helloworld", ext), nil
}

// Draw "Hello World"
func Draw(gc draw2d.GraphicContext, text string) {
	// Draw a rounded rectangle using default colors
	draw2dkit.RoundedRectangle(gc, 5, 5, 135, 95, 10, 10)
	gc.FillStroke()

	// Set the font luximbi.ttf
	gc.SetFontData(draw2d.FontData{Name: "luxi", Family: draw2d.FontFamilyMono, Style: draw2d.FontStyleBold | draw2d.FontStyleItalic})
	// Set the fill text color to black
	gc.SetFillColor(image.Black)
	gc.SetFontSize(14)
	// Display Hello World
	gc.FillStringAt("Hello World", 8, 52)
}

// Main draws vertically spaced lines and returns the filename.
// This should only be used during testing.
func Main(gc draw2d.GraphicContext, ext string) (string, error) {
	gc.SetFillRule(draw2d.FillRuleWinding)
	gc.Clear()
	// Draw the line
	for x := 5.0; x < 297; x += 10 {
		Draw(gc, x, 0, x, 210)
	}
	gc.ClearRect(100, 75, 197, 135)
	draw2dkit.Ellipse(gc, 148.5, 105, 35, 25)
	gc.SetFillColor(color.RGBA{0xff, 0xff, 0x44, 0xff})
	gc.FillStroke()

	// Return the output filename
	return samples.Output("line", ext), nil
}

// Main draws the tiger
func Main(gc draw2d.GraphicContext, ext string) (string, error) {
	gc.Save()

	// flip the image
	gc.Translate(0, 200)
	gc.Scale(0.35, -0.35)
	gc.Translate(70, -200)

	// Tiger postscript drawing
	tiger := samples.Resource("image", "tiger.ps", ext)

	// Draw tiger
	Draw(gc, tiger)
	gc.Restore()

	// Return the output filename
	return samples.Output("postscript", ext), nil
}

// Main draws a left hand and ear of a gopher. Afterwards it returns
// the filename. This should only be used during testing.
func Main(gc draw2d.GraphicContext, ext string) (string, error) {
	gc.Save()
	gc.Scale(0.5, 0.5)
	// Draw a (partial) gopher
	Draw(gc)
	gc.Restore()

	// Return the output filename
	return samples.Output("gopher", ext), nil
}

// PathTransform scales a path differently in horizontal and vertical direction.
func PathTransform(gc draw2d.GraphicContext, x, y, width, height float64) {
	gc.Save()
	gc.SetLineWidth(width / 10)
	gc.Translate(x+width/2, y+height/2)
	gc.Scale(1, 4)
	gc.ArcTo(0, 0, width/8, height/8, 0, math.Pi*2)
	gc.Close()
	gc.Stroke()
	gc.Restore()
}

// FillStyle demonstrates the difference between even odd and non zero winding rule.
func FillStyle(gc draw2d.GraphicContext, x, y, width, height float64) {
	sx, sy := width/232, height/220
	gc.SetLineWidth(width / 40)

	draw2dkit.Rectangle(gc, x+sx*0, y+sy*12, x+sx*232, y+sy*70)

	var wheel1, wheel2 draw2d.Path
	wheel1.ArcTo(x+sx*52, y+sy*70, sx*40, sy*40, 0, 2*math.Pi)
	wheel2.ArcTo(x+sx*180, y+sy*70, sx*40, sy*40, 0, -2*math.Pi)

	gc.SetFillRule(draw2d.FillRuleEvenOdd)
	gc.SetFillColor(color.NRGBA{0, 0xB2, 0, 0xFF})

	gc.SetStrokeColor(image.Black)
	gc.FillStroke(&wheel1, &wheel2)

	draw2dkit.Rectangle(gc, x, y+sy*140, x+sx*232, y+sy*198)
	wheel1.Clear()
	wheel1.ArcTo(x+sx*52, y+sy*198, sx*40, sy*40, 0, 2*math.Pi)
	wheel2.Clear()
	wheel2.ArcTo(x+sx*180, y+sy*198, sx*40, sy*40, 0, -2*math.Pi)

	gc.SetFillRule(draw2d.FillRuleWinding)
	gc.SetFillColor(color.NRGBA{0, 0, 0xE5, 0xFF})
	gc.FillStroke(&wheel1, &wheel2)
}

// FillStroke first fills and afterwards strokes a path.
func FillStroke(gc draw2d.GraphicContext, x, y, width, height float64) {
	sx, sy := width/210, height/215
	gc.MoveTo(x+sx*113.0, y)
	gc.LineTo(x+sx*215.0, y+sy*215)
	rLineTo(gc, sx*-100, 0)
	gc.CubicCurveTo(x+sx*35, y+sy*215, x+sx*35, y+sy*113, x+sx*113.0, y+sy*113)
	gc.Close()

	gc.MoveTo(x+sx*50.0, y)
	rLineTo(gc, sx*51.2, sy*51.2)
	rLineTo(gc, sx*-51.2, sy*51.2)
	rLineTo(gc, sx*-51.2, sy*-51.2)
	gc.Close()

	gc.SetLineWidth(width / 20.0)
	gc.SetFillColor(color.NRGBA{0, 0, 0xFF, 0xFF})
	gc.SetStrokeColor(image.Black)
	gc.FillStroke()
}

// FillString draws a filled and stroked string.
func FillString(gc draw2d.GraphicContext, x, y, width, height float64) {
	sx, sy := width/100, height/100
	gc.Save()
	gc.SetStrokeColor(image.Black)
	gc.SetLineWidth(1)
	draw2dkit.RoundedRectangle(gc, x+sx*5, y+sy*5, x+sx*95, y+sy*95, sx*10, sy*10)
	gc.FillStroke()
	gc.SetFillColor(image.Black)
	gc.SetFontSize(height / 6)
	gc.Translate(x+sx*6, y+sy*52)
	gc.SetFontData(draw2d.FontData{
		Name:   "luxi",
		Family: draw2d.FontFamilyMono,
		Style:  draw2d.FontStyleBold | draw2d.FontStyleItalic})
	w := gc.FillString("Hug")
	gc.Translate(w+sx, 0)
	left, top, right, bottom := gc.GetStringBounds("cou")
	gc.SetStrokeColor(color.NRGBA{255, 0x33, 0x33, 0x80})
	draw2dkit.Rectangle(gc, left, top, right, bottom)
	gc.SetLineWidth(height / 50)
	gc.Stroke()
	gc.SetFillColor(color.NRGBA{0x33, 0x33, 0xff, 0xff})
	gc.SetStrokeColor(color.NRGBA{0x33, 0x33, 0xff, 0xff})
	gc.SetLineWidth(height / 100)
	gc.StrokeString("Hug")
	gc.Restore()
}

// CubicCurve draws a cubic curve with its control points.
func CubicCurve(gc draw2d.GraphicContext, x, y, width, height float64) {
	sx, sy := width/162, height/205
	x0, y0 := x, y+sy*100.0
	x1, y1 := x+sx*75, y+sy*205
	x2, y2 := x+sx*125, y
	x3, y3 := x+sx*205, y+sy*100

	gc.SetStrokeColor(image.Black)
	gc.SetFillColor(color.NRGBA{0xAA, 0xAA, 0xAA, 0xFF})
	gc.SetLineWidth(width / 10)
	gc.MoveTo(x0, y0)
	gc.CubicCurveTo(x1, y1, x2, y2, x3, y3)
	gc.Stroke()

	gc.SetStrokeColor(color.NRGBA{0xFF, 0x33, 0x33, 0x88})

	gc.SetLineWidth(width / 20)
	// draw segment of curve
	gc.MoveTo(x0, y0)
	gc.LineTo(x1, y1)
	gc.LineTo(x2, y2)
	gc.LineTo(x3, y3)
	gc.Stroke()
}

// ArcNegative draws an arc with a negative angle (anti clockwise).
func ArcNegative(gc draw2d.GraphicContext, xc, yc, width, height float64) {
	xc += width / 2
	yc += height / 2
	radiusX, radiusY := width/2, height/2
	startAngle := 45.0 * (math.Pi / 180.0) /* angles are specified */
	angle := -225 * (math.Pi / 180.0)      /* clockwise in radians */
	gc.SetLineWidth(width / 10)
	gc.SetLineCap(draw2d.ButtCap)
	gc.SetStrokeColor(image.Black)

	gc.ArcTo(xc, yc, radiusX, radiusY, startAngle, angle)
	gc.Stroke()
	// fill a circle
	gc.SetStrokeColor(color.NRGBA{255, 0x33, 0x33, 0x80})
	gc.SetFillColor(color.NRGBA{255, 0x33, 0x33, 0x80})
	gc.SetLineWidth(width / 20)

	gc.MoveTo(xc+math.Cos(startAngle)*radiusX, yc+math.Sin(startAngle)*radiusY)
	gc.LineTo(xc, yc)
	gc.LineTo(xc-radiusX, yc)
	gc.Stroke()

	gc.ArcTo(xc, yc, width/10.0, height/10.0, 0, 2*math.Pi)
	gc.Fill()
}

// Draw a line with an angle with specified line cap and join
func Draw(gc draw2d.GraphicContext, cap draw2d.LineCap, join draw2d.LineJoin,
	x0, y0, x1, y1, offset float64) {
	gc.SetLineCap(cap)
	gc.SetLineJoin(join)

	// Draw thick line
	gc.SetStrokeColor(color.NRGBA{0x33, 0x33, 0x33, 0xFF})
	gc.SetLineWidth(30.0)
	gc.MoveTo(x0, y0)
	gc.LineTo((x0+x1)/2+offset, (y0+y1)/2)
	gc.LineTo(x1, y1)
	gc.Stroke()

	// Draw thin helping line
	gc.SetStrokeColor(color.NRGBA{0xFF, 0x33, 0x33, 0xFF})
	gc.SetLineWidth(2.56)
	gc.MoveTo(x0, y0)
	gc.LineTo((x0+x1)/2+offset, (y0+y1)/2)
	gc.LineTo(x1, y1)
	gc.Stroke()
}

// CurveRectangle draws a rectangle with bezier curves (not rounded rectangle).
func CurveRectangle(gc draw2d.GraphicContext, x0, y0,
	rectWidth, rectHeight float64, stroke, fill color.Color) {
	radius := (rectWidth + rectHeight) / 4

	x1 := x0 + rectWidth
	y1 := y0 + rectHeight
	if rectWidth/2 < radius {
		if rectHeight/2 < radius {
			gc.MoveTo(x0, (y0+y1)/2)
			gc.CubicCurveTo(x0, y0, x0, y0, (x0+x1)/2, y0)
			gc.CubicCurveTo(x1, y0, x1, y0, x1, (y0+y1)/2)
			gc.CubicCurveTo(x1, y1, x1, y1, (x1+x0)/2, y1)
			gc.CubicCurveTo(x0, y1, x0, y1, x0, (y0+y1)/2)
		} else {
			gc.MoveTo(x0, y0+radius)
			gc.CubicCurveTo(x0, y0, x0, y0, (x0+x1)/2, y0)
			gc.CubicCurveTo(x1, y0, x1, y0, x1, y0+radius)
			gc.LineTo(x1, y1-radius)
			gc.CubicCurveTo(x1, y1, x1, y1, (x1+x0)/2, y1)
			gc.CubicCurveTo(x0, y1, x0, y1, x0, y1-radius)
		}
	} else {
		if rectHeight/2 < radius {
			gc.MoveTo(x0, (y0+y1)/2)
			gc.CubicCurveTo(x0, y0, x0, y0, x0+radius, y0)
			gc.LineTo(x1-radius, y0)
			gc.CubicCurveTo(x1, y0, x1, y0, x1, (y0+y1)/2)
			gc.CubicCurveTo(x1, y1, x1, y1, x1-radius, y1)
			gc.LineTo(x0+radius, y1)
			gc.CubicCurveTo(x0, y1, x0, y1, x0, (y0+y1)/2)
		} else {
			gc.MoveTo(x0, y0+radius)
			gc.CubicCurveTo(x0, y0, x0, y0, x0+radius, y0)
			gc.LineTo(x1-radius, y0)
			gc.CubicCurveTo(x1, y0, x1, y0, x1, y0+radius)
			gc.LineTo(x1, y1-radius)
			gc.CubicCurveTo(x1, y1, x1, y1, x1-radius, y1)
			gc.LineTo(x0+radius, y1)
			gc.CubicCurveTo(x0, y1, x0, y1, x0, y1-radius)
		}
	}
	gc.Close()
	gc.SetStrokeColor(stroke)
	gc.SetFillColor(fill)
	gc.SetLineWidth(10.0)
	gc.FillStroke()
}

// Draw a gopher head (not rotated)
func Draw(gc draw2d.GraphicContext, x, y, w, h float64) {
	h23 := (h * 2) / 3

	blf := color.RGBA{0, 0, 0, 0xff}          // black
	wf := color.RGBA{0xff, 0xff, 0xff, 0xff}  // white
	nf := color.RGBA{0x8B, 0x45, 0x13, 0xff}  // brown opaque
	brf := color.RGBA{0x8B, 0x45, 0x13, 0x99} // brown transparant
	brb := color.RGBA{0x8B, 0x45, 0x13, 0xBB} // brown transparant

	// round head top
	gc.MoveTo(x, y+h*1.002)
	gc.CubicCurveTo(x+w/4, y-h/3, x+3*w/4, y-h/3, x+w, y+h*1.002)
	gc.Close()
	gc.SetFillColor(brb)
	gc.Fill()

	// rectangle head bottom
	draw2dkit.RoundedRectangle(gc, x, y+h, x+w, y+h+h, h/5, h/5)
	gc.Fill()

	// left ear outside
	draw2dkit.Circle(gc, x, y+h, w/12)
	gc.SetFillColor(brf)
	gc.Fill()

	// left ear inside
	draw2dkit.Circle(gc, x, y+h, 0.5*w/12)
	gc.SetFillColor(nf)
	gc.Fill()

	// right ear outside
	draw2dkit.Circle(gc, x+w, y+h, w/12)
	gc.SetFillColor(brf)
	gc.Fill()

	// right ear inside
	draw2dkit.Circle(gc, x+w, y+h, 0.5*w/12)
	gc.SetFillColor(nf)
	gc.Fill()

	// left eye outside white
	draw2dkit.Circle(gc, x+w/3, y+h23, w/9)
	gc.SetFillColor(wf)
	gc.Fill()

	// left eye black
	draw2dkit.Circle(gc, x+w/3+w/24, y+h23, 0.5*w/9)
	gc.SetFillColor(blf)
	gc.Fill()

	// left eye inside white
	draw2dkit.Circle(gc, x+w/3+w/24+w/48, y+h23, 0.2*w/9)
	gc.SetFillColor(wf)
	gc.Fill()

	// right eye outside white
	draw2dkit.Circle(gc, x+w-w/3, y+h23, w/9)
	gc.Fill()

	// right eye black
	draw2dkit.Circle(gc, x+w-w/3+w/24, y+h23, 0.5*w/9)
	gc.SetFillColor(blf)
	gc.Fill()

	// right eye inside white
	draw2dkit.Circle(gc, x+w-(w/3)+w/24+w/48, y+h23, 0.2*w/9)
	gc.SetFillColor(wf)
	gc.Fill()

	// left tooth
	gc.SetFillColor(wf)
	draw2dkit.RoundedRectangle(gc, x+w/2-w/8, y+h+h/2.5, x+w/2-w/8+w/8, y+h+h/2.5+w/6, w/10, w/10)
	gc.Fill()

	// right tooth
	draw2dkit.RoundedRectangle(gc, x+w/2, y+h+h/2.5, x+w/2+w/8, y+h+h/2.5+w/6, w/10, w/10)
	gc.Fill()

	// snout
	draw2dkit.Ellipse(gc, x+(w/2), y+h+h/2.5, w/6, w/12)
	gc.SetFillColor(nf)
	gc.Fill()

	// nose
	draw2dkit.Ellipse(gc, x+(w/2), y+h+h/7, w/10, w/12)
	gc.SetFillColor(blf)
	gc.Fill()
}

// Main draws a rotated face of the gopher. Afterwards it returns
// the filename. This should only be used during testing.
func Main(gc draw2d.GraphicContext, ext string) (string, error) {
	gc.SetStrokeColor(image.Black)
	gc.SetFillColor(image.White)
	gc.Save()
	// Draw a (partial) gopher
	gc.Translate(-60, 65)
	gc.Rotate(-30 * (math.Pi / 180.0))
	Draw(gc, 48, 48, 240, 72)
	gc.Restore()

	// Return the output filename
	return samples.Output("gopher2", ext), nil
}