Golang draw2d.GraphicContext類代碼示例

// 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
}

// Draw the image frame with certain parameters.
func Draw(gc draw2d.GraphicContext, png string,
	dw, dh, margin, lineWidth float64) error {
	// Draw frame
	draw2dkit.RoundedRectangle(gc, lineWidth, lineWidth, dw-lineWidth, dh-lineWidth, 100, 100)
	gc.SetLineWidth(lineWidth)
	gc.FillStroke()

	// load the source image
	source, err := draw2dimg.LoadFromPngFile(png)
	if err != nil {
		return err
	}
	// Size of source image
	sw, sh := float64(source.Bounds().Dx()), float64(source.Bounds().Dy())
	// Draw image to fit in the frame
	// TODO Seems to have a transform bug here on draw image
	scale := math.Min((dw-margin*2)/sw, (dh-margin*2)/sh)
	gc.Save()
	gc.Translate((dw-sw*scale)/2, (dh-sh*scale)/2)
	gc.Scale(scale, scale)
	gc.Rotate(0.2)

	gc.DrawImage(source)
	gc.Restore()
	return nil
}

// Draw the droid on a certain position.
func Draw(gc draw2d.GraphicContext, x, y float64) {
	// set the fill and stroke color of the droid
	gc.SetFillColor(color.RGBA{0x44, 0xff, 0x44, 0xff})
	gc.SetStrokeColor(color.RGBA{0x44, 0x44, 0x44, 0xff})

	// set line properties
	gc.SetLineCap(draw2d.RoundCap)
	gc.SetLineWidth(5)

	// head
	gc.MoveTo(x+30, y+70)
	gc.ArcTo(x+80, y+70, 50, 50, 180*(math.Pi/180), 180*(math.Pi/180))
	gc.Close()
	gc.FillStroke()
	gc.MoveTo(x+60, y+25)
	gc.LineTo(x+50, y+10)
	gc.MoveTo(x+100, y+25)
	gc.LineTo(x+110, y+10)
	gc.Stroke()

	// left eye
	draw2dkit.Circle(gc, x+60, y+45, 5)
	gc.FillStroke()

	// right eye
	draw2dkit.Circle(gc, x+100, y+45, 5)
	gc.FillStroke()

	// body
	draw2dkit.RoundedRectangle(gc, x+30, y+75, x+30+100, y+75+90, 10, 10)
	gc.FillStroke()
	draw2dkit.Rectangle(gc, x+30, y+75, x+30+100, y+75+80)
	gc.FillStroke()

	// left arm
	draw2dkit.RoundedRectangle(gc, x+5, y+80, x+5+20, y+80+70, 10, 10)
	gc.FillStroke()

	// right arm
	draw2dkit.RoundedRectangle(gc, x+135, y+80, x+135+20, y+80+70, 10, 10)
	gc.FillStroke()

	// left leg
	draw2dkit.RoundedRectangle(gc, x+50, y+150, x+50+20, y+150+50, 10, 10)
	gc.FillStroke()

	// right leg
	draw2dkit.RoundedRectangle(gc, x+90, y+150, x+90+20, y+150+50, 10, 10)
	gc.FillStroke()
}

// Draw a left hand and ear of a gopher using a gc thanks to
// https://github.com/golang-samples/gopher-vector/
func Draw(gc draw2d.GraphicContext) {
	// Initialize Stroke Attribute
	gc.SetLineWidth(3)
	gc.SetLineCap(draw2d.RoundCap)
	gc.SetStrokeColor(color.Black)

	// Left hand
	// <path fill-rule="evenodd" clip-rule="evenodd" fill="#F6D2A2" stroke="#000000" stroke-width="3" stroke-linecap="round" d="
	// M10.634,300.493c0.764,15.751,16.499,8.463,23.626,3.539c6.765-4.675,8.743-0.789,9.337-10.015
	// c0.389-6.064,1.088-12.128,0.744-18.216c-10.23-0.927-21.357,1.509-29.744,7.602C10.277,286.542,2.177,296.561,10.634,300.493"/>
	gc.SetFillColor(color.RGBA{0xF6, 0xD2, 0xA2, 0xff})
	gc.MoveTo(10.634, 300.493)
	rCubicCurveTo(gc, 0.764, 15.751, 16.499, 8.463, 23.626, 3.539)
	rCubicCurveTo(gc, 6.765, -4.675, 8.743, -0.789, 9.337, -10.015)
	rCubicCurveTo(gc, 0.389, -6.064, 1.088, -12.128, 0.744, -18.216)
	rCubicCurveTo(gc, -10.23, -0.927, -21.357, 1.509, -29.744, 7.602)
	gc.CubicCurveTo(10.277, 286.542, 2.177, 296.561, 10.634, 300.493)
	gc.FillStroke()

	// <path fill-rule="evenodd" clip-rule="evenodd" fill="#C6B198" stroke="#000000" stroke-width="3" stroke-linecap="round" d="
	// M10.634,300.493c2.29-0.852,4.717-1.457,6.271-3.528"/>
	gc.MoveTo(10.634, 300.493)
	rCubicCurveTo(gc, 2.29, -0.852, 4.717, -1.457, 6.271, -3.528)
	gc.Stroke()

	// Left Ear
	// <path fill-rule="evenodd" clip-rule="evenodd" fill="#6AD7E5" stroke="#000000" stroke-width="3" stroke-linecap="round" d="
	// M46.997,112.853C-13.3,95.897,31.536,19.189,79.956,50.74L46.997,112.853z"/>
	gc.MoveTo(46.997, 112.853)
	gc.CubicCurveTo(-13.3, 95.897, 31.536, 19.189, 79.956, 50.74)
	gc.LineTo(46.997, 112.853)
	gc.Close()
	gc.Stroke()
}

// 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()
}

// Star draws many lines from a center.
func Star(gc draw2d.GraphicContext, x, y, width, height float64) {
	gc.Save()
	gc.Translate(x+width/2, y+height/2)
	gc.SetLineWidth(width / 40)
	for i := 0.0; i < 360; i = i + 10 { // Go from 0 to 360 degrees in 10 degree steps
		gc.Save()                        // Keep rotations temporary
		gc.Rotate(i * (math.Pi / 180.0)) // Rotate by degrees on stack from 'for'
		gc.MoveTo(0, 0)
		gc.LineTo(width/2, 0)
		gc.Stroke()
		gc.Restore()
	}
	gc.Restore()
}

// 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()
}

// 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()
}

// Bubble draws a text balloon.
func Bubble(gc draw2d.GraphicContext, x, y, width, height float64) {
	sx, sy := width/100, height/100
	gc.MoveTo(x+sx*50, y)
	gc.QuadCurveTo(x, y, x, y+sy*37.5)
	gc.QuadCurveTo(x, y+sy*75, x+sx*25, y+sy*75)
	gc.QuadCurveTo(x+sx*25, y+sy*95, x+sx*5, y+sy*100)
	gc.QuadCurveTo(x+sx*35, y+sy*95, x+sx*40, y+sy*75)
	gc.QuadCurveTo(x+sx*100, y+sy*75, x+sx*100, y+sy*37.5)
	gc.QuadCurveTo(x+sx*100, y, x+sx*50, y)
	gc.Stroke()
}

// 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()
}