draw2d

package module
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 Go to latest Published: Jul 14, 2015 License: BSD-2-Clause Imports: 15 Imported by: 0

README

draw2d

Package draw2d is a pure go 2D vector graphics library with support for multiple output devices such as images (draw2d), pdf documents (draw2dpdf) and opengl (draw2dgl), which can also be used on the google app engine. It can be used as a pure go Cairo alternative. draw2d is released under the BSD license. See the documentation for more details.

geometrypostscript

Click on an image above to get the pdf, generated with exactly the same draw2d code. The first image is the output of samples/geometry. The second image is the result of samples/postcript, which demonstrates that draw2d can draw postscript files into images or pdf documents with the ps package.

Features

Operations in draw2d include stroking and filling polygons, arcs, Bézier curves, drawing images and text rendering with truetype fonts. All drawing operations can be transformed by affine transformations (scale, rotation, translation).

Package draw2d follows the conventions of the HTML Canvas 2D Context for coordinate system, angles, etc...

Installation

Install golang. To install or update the package draw2d on your system, run:

go get -u github.com/llgcode/draw2d

Quick Start

The following Go code generates a simple drawing and saves it to an image file with package draw2d:

// Initialize the graphic context on an RGBA image
dest := image.NewRGBA(image.Rect(0, 0, 297, 210.0))
gc := draw2d.NewGraphicContext(dest)

// Set some properties
gc.SetFillColor(color.RGBA{0x44, 0xff, 0x44, 0xff})
gc.SetStrokeColor(color.RGBA{0x44, 0x44, 0x44, 0xff})
gc.SetLineWidth(5)

// Draw a closed shape
gc.MoveTo(10, 10) // should always be called first for a new path
gc.LineTo(100, 50)
gc.QuadCurveTo(100, 10, 10, 10)
gc.Close()
gc.FillStroke()

// Save to file
draw2d.SaveToPngFile("hello.png", dest)

The same Go code can also generate a pdf document with package draw2dpdf:

// Initialize the graphic context on an RGBA image
dest := draw2dpdf.NewPdf("L", "mm", "A4")
gc := draw2d.NewGraphicContext(dest)

// Set some properties
gc.SetFillColor(color.RGBA{0x44, 0xff, 0x44, 0xff})
gc.SetStrokeColor(color.RGBA{0x44, 0x44, 0x44, 0xff})
gc.SetLineWidth(5)

// Draw a closed shape
gc.MoveTo(10, 10) // should always be called first for a new path
gc.LineTo(100, 50)
gc.QuadCurveTo(100, 10, 10, 10)
gc.Close()
gc.FillStroke()

// Save to file
draw2dpdf.SaveToPdfFile("hello.pdf", dest)

There are more examples here: https://github.com/llgcode/draw2d/tree/master/samples

Drawing on opengl is provided by the draw2dgl package.

Testing

The samples are run as tests from the root package folder draw2d by:

go test ./...

Or if you want to run with test coverage:

go test -cover ./... | grep -v "no test"

This will generate output by the different backends in the output folder.

Acknowledgments

Laurent Le Goff wrote this library, inspired by Postscript and HTML5 canvas. He implemented the image and opengl backend with the freetype-go package. Also he created a pure go Postscript interpreter, which can read postscript images and draw to a draw2d graphic context. Stani Michiels implemented the pdf backend with the gofpdf package.

Packages using draw2d

  • ps: Postscript interpreter written in Go
  • gonum/plot: drawing plots in Go
  • go.uik: a concurrent UI kit written in pure go.
  • smartcrop: content aware image cropping
  • karta: drawing Voronoi diagrams
  • chart: basic charts in Go

References

Documentation

Overview

Package draw2d is a pure go 2D vector graphics library with support for multiple output devices such as images (draw2d), pdf documents (draw2dpdf) and opengl (draw2dgl), which can also be used on the google app engine. It can be used as a pure go Cairo alternative. draw2d is released under the BSD license.

Features

Operations in draw2d include stroking and filling polygons, arcs, Bézier curves, drawing images and text rendering with truetype fonts. All drawing operations can be transformed by affine transformations (scale, rotation, translation).

Package draw2d follows the conventions of http://www.w3.org/TR/2dcontext for coordinate system, angles, etc...

Installation

To install or update the package draw2d on your system, run: 

go get -u github.com/llgcode/draw2d

Quick Start

Package draw2d itself provides a graphic context that can draw vector graphics and text on an image canvas. The following Go code generates a simple drawing and saves it to an image file: 

// Initialize the graphic context on an RGBA image
dest := image.NewRGBA(image.Rect(0, 0, 297, 210.0))
gc := draw2d.NewGraphicContext(dest)

// Set some properties
gc.SetFillColor(color.RGBA{0x44, 0xff, 0x44, 0xff})
gc.SetStrokeColor(color.RGBA{0x44, 0x44, 0x44, 0xff})
gc.SetLineWidth(5)

// Draw a closed shape
gc.MoveTo(10, 10) // should always be called first for a new path
gc.LineTo(100, 50)
gc.QuadCurveTo(100, 10, 10, 10)
gc.Close()
gc.FillStroke()

// Save to file
draw2d.SaveToPngFile("hello.png", dest)

There are more examples here: https://github.com/llgcode/draw2d/tree/master/samples

Drawing on pdf documents is provided by the draw2dpdf package. Drawing on opengl is provided by the draw2dgl package. See subdirectories at the bottom of this page.

Testing

The samples are run as tests from the root package folder `draw2d` by: 

go test ./...

Or if you want to run with test coverage: 

go test -cover ./... | grep -v "no test"

This will generate output by the different backends in the output folder.

Acknowledgments

Laurent Le Goff wrote this library, inspired by Postscript and HTML5 canvas. He implemented the image and opengl backend with the freetype-go package. Also he created a pure go Postscript interpreter, which can read postscript images and draw to a draw2d graphic context (https://github.com/llgcode/ps). Stani Michiels implemented the pdf backend with the gofpdf package.

Packages using draw2d

- https://github.com/llgcode/ps: Postscript interpreter written in Go

- https://github.com/gonum/plot: drawing plots in Go

- https://github.com/muesli/smartcrop: content aware image cropping

- https://github.com/peterhellberg/karta: drawing Voronoi diagrams

- https://github.com/vdobler/chart: basic charts in Go

Index

Constants

View Source 
const M = 1<<16 - 1

Variables

View Source 
var (
	CurveRecursionLimit        = 32
	CurveCollinearityEpsilon   = 1e-30
	CurveAngleToleranceEpsilon = 0.01
)

Functions

func Circle 

func Circle(path Path, cx, cy, radius float64)

Circle is drawn with center (cx,cy) and radius

func DrawImage 

func DrawImage(src image.Image, dest draw.Image, tr MatrixTransform, op draw.Op, filter ImageFilter)

DrawImage draws a source image on an destination image.

func Ellipse 

func Ellipse(path Path, cx, cy, rx, ry float64)

Ellipse is drawn with center (cx,cy) and radius (rx,ry)

func FontFileName 

func FontFileName(fontData FontData) string

func GetFont 

func GetFont(fontData FontData) *truetype.Font

func GetFontFolder 

func GetFontFolder() string

func LoadFromPngFile 

func LoadFromPngFile(filePath string) (image.Image, error)

LoadFromPngFile Open a png file

func Rect 

func Rect(path Path, x1, y1, x2, y2 float64)

Rect draws a rectangle between (x1,y1) and (x2,y2)

func RegisterFont 

func RegisterFont(fontData FontData, font *truetype.Font)

func RoundRect 

func RoundRect(path Path, x1, y1, x2, y2, arcWidth, arcHeight float64)

RoundRect draws a rectangle between (x1,y1) and (x2,y2) with rounded corners

func SaveToPngFile 

func SaveToPngFile(filePath string, m image.Image) error

SaveToPngFile create and save an image to a file using PNG format

func SetFontFolder 

func SetFontFolder(folder string)

Types

type Cap 

type Cap int
const (
	RoundCap Cap = iota
	ButtCap
	SquareCap
)

func (Cap) Convert 

func (c Cap) Convert() raster.Capper

type ContextStack 

type ContextStack struct {
	Tr          MatrixTransform
	Path        *PathStorage
	LineWidth   float64
	Dash        []float64
	DashOffset  float64
	StrokeColor color.Color
	FillColor   color.Color
	FillRule    FillRule
	Cap         Cap
	Join        Join
	FontSize    float64
	FontData    FontData

	Font *truetype.Font
	// fontSize and dpi are used to calculate scale. scale is the number of
	// 26.6 fixed point units in 1 em.
	Scale float64
	// contains filtered or unexported fields
}

type DashVertexConverter 

type DashVertexConverter struct {
	// contains filtered or unexported fields
}

func NewDashConverter 

func NewDashConverter(dash []float64, dashOffset float64, converter VertexConverter) *DashVertexConverter

func (*DashVertexConverter) NextCommand 

func (dasher *DashVertexConverter) NextCommand(cmd VertexCommand)

func (*DashVertexConverter) Vertex 

func (dasher *DashVertexConverter) Vertex(x, y float64)

type DemuxConverter 

type DemuxConverter struct {
	// contains filtered or unexported fields
}

func NewDemuxConverter 

func NewDemuxConverter(converters ...VertexConverter) *DemuxConverter

func (*DemuxConverter) NextCommand 

func (dc *DemuxConverter) NextCommand(cmd VertexCommand)

func (*DemuxConverter) Vertex 

func (dc *DemuxConverter) Vertex(x, y float64)

type FillRule 

type FillRule int

FillRule defines the type for fill rules 

const (
	// FillRuleEvenOdd defines the even odd filling rule
	FillRuleEvenOdd FillRule = iota
	// FillRuleWinding defines the non zero winding rule
	FillRuleWinding
)

func (FillRule) UseNonZeroWinding 

func (f FillRule) UseNonZeroWinding() bool

type FontData 

type FontData struct {
	Name   string
	Family FontFamily
	Style  FontStyle
}

type FontFamily 

type FontFamily byte
const (
	FontFamilySans FontFamily = iota
	FontFamilySerif
	FontFamilyMono
)

type FontStyle 

type FontStyle byte
const (
	FontStyleNormal FontStyle = iota
	FontStyleBold
	FontStyleItalic
)

type GraphicContext 

type GraphicContext interface {
	Path
	// Create a new path
	BeginPath()
	GetMatrixTransform() MatrixTransform
	SetMatrixTransform(tr MatrixTransform)
	ComposeMatrixTransform(tr MatrixTransform)
	Rotate(angle float64)
	Translate(tx, ty float64)
	Scale(sx, sy float64)
	SetStrokeColor(c color.Color)
	SetFillColor(c color.Color)
	SetFillRule(f FillRule)
	SetLineWidth(lineWidth float64)
	SetLineCap(cap Cap)
	SetLineJoin(join Join)
	SetLineDash(dash []float64, dashOffset float64)
	SetFontSize(fontSize float64)
	GetFontSize() float64
	SetFontData(fontData FontData)
	GetFontData() FontData
	DrawImage(image image.Image)
	Save()
	Restore()
	Clear()
	ClearRect(x1, y1, x2, y2 int)
	SetDPI(dpi int)
	GetDPI() int
	GetStringBounds(s string) (left, top, right, bottom float64)
	CreateStringPath(text string, x, y float64) (cursor float64)
	FillString(text string) (cursor float64)
	FillStringAt(text string, x, y float64) (cursor float64)
	StrokeString(text string) (cursor float64)
	StrokeStringAt(text string, x, y float64) (cursor float64)
	Stroke(paths ...*PathStorage)
	Fill(paths ...*PathStorage)
	FillStroke(paths ...*PathStorage)
}

GraphicContext describes the interface for the various backends (images, pdf, opengl, ...)

type ImageFilter 

type ImageFilter int

ImageFilter defines sampling filter (linear, bilinear or bicubic) 

const (
	// LinearFilter uses linear interpolation
	LinearFilter ImageFilter = iota
	// BilinearFilter uses bilinear interpolation
	BilinearFilter
	// BicubicFilter uses bicubic interpolation
	BicubicFilter
)

type ImageGraphicContext 

type ImageGraphicContext struct {
	*StackGraphicContext

	DPI int
	// contains filtered or unexported fields
}

func NewGraphicContext 

func NewGraphicContext(img draw.Image) *ImageGraphicContext

NewGraphicContext creates a new Graphic context from an image.

func NewGraphicContextWithPainter 

func NewGraphicContextWithPainter(img draw.Image, painter Painter) *ImageGraphicContext

NewGraphicContextWithPainter creates a new Graphic context from an image and a Painter (see Freetype-go)

func (*ImageGraphicContext) Clear 

func (gc *ImageGraphicContext) Clear()

func (*ImageGraphicContext) ClearRect 

func (gc *ImageGraphicContext) ClearRect(x1, y1, x2, y2 int)

func (*ImageGraphicContext) CreateStringPath 

func (gc *ImageGraphicContext) CreateStringPath(s string, x, y float64) float64

CreateStringPath creates a path from the string s at x, y, and returns the string width. The text is placed so that the left edge of the em square of the first character of s and the baseline intersect at x, y. The majority of the affected pixels will be above and to the right of the point, but some may be below or to the left. For example, drawing a string that starts with a 'J' in an italic font may affect pixels below and left of the point.

func (*ImageGraphicContext) DrawImage 

func (gc *ImageGraphicContext) DrawImage(img image.Image)

func (*ImageGraphicContext) Fill 

func (gc *ImageGraphicContext) Fill(paths ...*PathStorage)

Fill fills the paths with the color specified by SetFillColor

func (*ImageGraphicContext) FillString 

func (gc *ImageGraphicContext) FillString(text string) (cursor float64)

func (*ImageGraphicContext) FillStringAt 

func (gc *ImageGraphicContext) FillStringAt(text string, x, y float64) (cursor float64)

func (*ImageGraphicContext) FillStroke 

func (gc *ImageGraphicContext) FillStroke(paths ...*PathStorage)

FillStroke first fills the paths and than strokes them

func (*ImageGraphicContext) GetDPI 

func (gc *ImageGraphicContext) GetDPI() int

func (*ImageGraphicContext) GetStringBounds 

func (gc *ImageGraphicContext) GetStringBounds(s string) (left, top, right, bottom float64)

GetStringBounds returns the approximate pixel bounds of the string s at x, y. The left edge of the em square of the first character of s and the baseline intersect at 0, 0 in the returned coordinates. Therefore the top and left coordinates may well be negative.

func (*ImageGraphicContext) SetDPI 

func (gc *ImageGraphicContext) SetDPI(dpi int)

SetDPI sets the screen resolution in dots per inch.

func (*ImageGraphicContext) SetFont 

func (gc *ImageGraphicContext) SetFont(font *truetype.Font)

SetFont sets the font used to draw text.

func (*ImageGraphicContext) SetFontSize 

func (gc *ImageGraphicContext) SetFontSize(fontSize float64)

SetFontSize sets the font size in points (as in “a 12 point font”).

func (*ImageGraphicContext) Stroke 

func (gc *ImageGraphicContext) Stroke(paths ...*PathStorage)

Stroke strokes the paths with the color specified by SetStrokeColor

func (*ImageGraphicContext) StrokeString 

func (gc *ImageGraphicContext) StrokeString(text string) (cursor float64)

func (*ImageGraphicContext) StrokeStringAt 

func (gc *ImageGraphicContext) StrokeStringAt(text string, x, y float64) (cursor float64)

type Join 

type Join int
const (
	BevelJoin Join = iota
	RoundJoin
	MiterJoin
)

func (Join) Convert 

func (j Join) Convert() raster.Joiner

type LineStroker 

type LineStroker struct {
	Next          VertexConverter
	HalfLineWidth float64
	Cap           Cap
	Join          Join
	// contains filtered or unexported fields
}

func NewLineStroker 

func NewLineStroker(c Cap, j Join, converter VertexConverter) *LineStroker

func (*LineStroker) NextCommand 

func (l *LineStroker) NextCommand(command VertexCommand)

func (*LineStroker) Vertex 

func (l *LineStroker) Vertex(x, y float64)

type MatrixTransform 

type MatrixTransform [6]float64

func NewIdentityMatrix 

func NewIdentityMatrix() MatrixTransform

* Creates an identity transformation.

func NewMatrixTransform 

func NewMatrixTransform(rectangle1, rectangle2 [4]float64) MatrixTransform

*

  • Creates a transformation, combining a scale and a translation, that transform rectangle1 into rectangle2.

func NewRotationMatrix 

func NewRotationMatrix(angle float64) MatrixTransform

*

  • Creates a rotation transformation.

func NewScaleMatrix 

func NewScaleMatrix(sx, sy float64) MatrixTransform

*

  • Creates a transformation with a sx, sy scale factor

func NewTranslationMatrix 

func NewTranslationMatrix(tx, ty float64) MatrixTransform

*

  • Creates a transformation with a translation, that,
  • transform point1 into point2.

func (MatrixTransform) Determinant 

func (tr MatrixTransform) Determinant() float64

func (MatrixTransform) Equals 

func (tr1 MatrixTransform) Equals(tr2 MatrixTransform) bool

*

  • Tests if a two transformation are equal. A tolerance is applied when
  • comparing matrix elements.

func (MatrixTransform) GetInverseTransformation 

func (tr MatrixTransform) GetInverseTransformation() MatrixTransform

*

  • Returns a transformation that is the inverse of the given transformation.

func (MatrixTransform) GetMaxAbsScaling 

func (tr MatrixTransform) GetMaxAbsScaling() (s float64)

func (MatrixTransform) GetMinAbsScaling 

func (tr MatrixTransform) GetMinAbsScaling() (s float64)

func (MatrixTransform) GetScale 

func (tr MatrixTransform) GetScale() float64

func (MatrixTransform) GetScaling 

func (tr MatrixTransform) GetScaling() (x, y float64)

func (MatrixTransform) GetTranslation 

func (tr MatrixTransform) GetTranslation() (x, y float64)

func (MatrixTransform) InverseTransform 

func (tr MatrixTransform) InverseTransform(points ...*float64)

func (MatrixTransform) IsIdentity 

func (tr MatrixTransform) IsIdentity() bool

*

  • Tests if a transformation is the identity transformation. A tolerance
  • is applied when comparing matrix elements.

func (MatrixTransform) IsTranslation 

func (tr MatrixTransform) IsTranslation() bool

*

  • Tests if a transformation is is a pure translation. A tolerance
  • is applied when comparing matrix elements.

func (MatrixTransform) Multiply 

func (tr1 MatrixTransform) Multiply(tr2 MatrixTransform) MatrixTransform

func (*MatrixTransform) Rotate 

func (tr *MatrixTransform) Rotate(angle float64) *MatrixTransform

func (*MatrixTransform) Scale 

func (tr *MatrixTransform) Scale(sx, sy float64) *MatrixTransform

func (MatrixTransform) Transform 

func (tr MatrixTransform) Transform(points ...*float64)

func (MatrixTransform) TransformArray 

func (tr MatrixTransform) TransformArray(points []float64)

func (MatrixTransform) TransformRasterPoint 

func (tr MatrixTransform) TransformRasterPoint(points ...*raster.Point)

func (MatrixTransform) TransformRectangle 

func (tr MatrixTransform) TransformRectangle(x0, y0, x2, y2 *float64)

func (*MatrixTransform) Translate 

func (tr *MatrixTransform) Translate(tx, ty float64) *MatrixTransform

func (MatrixTransform) VectorTransform 

func (tr MatrixTransform) VectorTransform(points ...*float64)

type MatrixTransformAdder 

type MatrixTransformAdder struct {
	// contains filtered or unexported fields
}

this adder apply a Matrix transformation to points

func NewMatrixTransformAdder 

func NewMatrixTransformAdder(tr MatrixTransform, adder raster.Adder) *MatrixTransformAdder

func (MatrixTransformAdder) Add1 

func (mta MatrixTransformAdder) Add1(b raster.Point)

Add1 adds a linear segment to the current curve.

func (MatrixTransformAdder) Add2 

func (mta MatrixTransformAdder) Add2(b, c raster.Point)

Add2 adds a quadratic segment to the current curve.

func (MatrixTransformAdder) Add3 

func (mta MatrixTransformAdder) Add3(b, c, d raster.Point)

Add3 adds a cubic segment to the current curve.

func (MatrixTransformAdder) Start 

func (mta MatrixTransformAdder) Start(a raster.Point)

Start starts a new curve at the given point.

type Painter 

type Painter interface {
	raster.Painter
	SetColor(color color.Color)
}

type Path 

type Path interface {
	// LastPoint returns the current point of the path
	LastPoint() (x, y float64)
	// MoveTo creates a new subpath that start at the specified point
	MoveTo(x, y float64)
	// RMoveTo creates a new subpath that start at the specified point
	// relative to the current point
	RMoveTo(dx, dy float64)
	// LineTo adds a line to the current subpath
	LineTo(x, y float64)
	// RLineTo adds a line to the current subpath
	// relative to the current point
	RLineTo(dx, dy float64)
	// QuadCurveTo adds a quadratic Bézier curve to the current subpath
	QuadCurveTo(cx, cy, x, y float64)
	// QuadCurveTo adds a quadratic Bézier curve to the current subpath
	// relative to the current point
	RQuadCurveTo(dcx, dcy, dx, dy float64)
	// CubicCurveTo adds a cubic Bézier curve to the current subpath
	CubicCurveTo(cx1, cy1, cx2, cy2, x, y float64)
	// RCubicCurveTo adds a cubic Bézier curve to the current subpath
	// relative to the current point
	RCubicCurveTo(dcx1, dcy1, dcx2, dcy2, dx, dy float64)
	// ArcTo adds an arc to the current subpath
	ArcTo(cx, cy, rx, ry, startAngle, angle float64)
	// RArcTo adds an arc to the current subpath
	// relative to the current point
	RArcTo(dcx, dcy, rx, ry, startAngle, angle float64)
	// Close creates a line from the current point to the last MoveTo
	// point (if not the same) and mark the path as closed so the
	// first and last lines join nicely.
	Close()
}

Path describes the interface for path drawing.

type PathAdder 

type PathAdder struct {
	ApproximationScale float64
	// contains filtered or unexported fields
}

func NewPathAdder 

func NewPathAdder(adder raster.Adder) *PathAdder

func (*PathAdder) Convert 

func (pathAdder *PathAdder) Convert(paths ...*PathStorage)

type PathCmd 

type PathCmd int
const (
	MoveTo PathCmd = iota
	LineTo
	QuadCurveTo
	CubicCurveTo
	ArcTo
	Close
)

type PathConverter 

type PathConverter struct {
	ApproximationScale, AngleTolerance, CuspLimit float64
	// contains filtered or unexported fields
}

func NewPathConverter 

func NewPathConverter(converter VertexConverter) *PathConverter

func (*PathConverter) ArcTo 

func (c *PathConverter) ArcTo(cx, cy, rx, ry, startAngle, angle float64) *PathConverter

func (*PathConverter) Close 

func (c *PathConverter) Close() *PathConverter

func (*PathConverter) Convert 

func (c *PathConverter) Convert(paths ...*PathStorage)

func (*PathConverter) ConvertCommand 

func (c *PathConverter) ConvertCommand(cmd PathCmd, vertices ...float64) int

func (*PathConverter) CubicCurveTo 

func (c *PathConverter) CubicCurveTo(cx1, cy1, cx2, cy2, x, y float64) *PathConverter

func (*PathConverter) LineTo 

func (c *PathConverter) LineTo(x, y float64) *PathConverter

func (*PathConverter) MoveTo 

func (c *PathConverter) MoveTo(x, y float64) *PathConverter

func (*PathConverter) QuadCurveTo 

func (c *PathConverter) QuadCurveTo(cx, cy, x, y float64) *PathConverter

func (*PathConverter) RArcTo 

func (c *PathConverter) RArcTo(dcx, dcy, rx, ry, startAngle, angle float64) *PathConverter

func (*PathConverter) RCubicCurveTo 

func (c *PathConverter) RCubicCurveTo(dcx1, dcy1, dcx2, dcy2, dx, dy float64) *PathConverter

func (*PathConverter) RLineTo 

func (c *PathConverter) RLineTo(dx, dy float64) *PathConverter

func (*PathConverter) RMoveTo 

func (c *PathConverter) RMoveTo(dx, dy float64) *PathConverter

func (*PathConverter) RQuadCurveTo 

func (c *PathConverter) RQuadCurveTo(dcx, dcy, dx, dy float64) *PathConverter

type PathStorage 

type PathStorage struct {
	Commands []PathCmd
	Vertices []float64
	// contains filtered or unexported fields
}

func NewPathStorage 

func NewPathStorage() (p *PathStorage)

func (*PathStorage) ArcTo 

func (p *PathStorage) ArcTo(cx, cy, rx, ry, startAngle, angle float64) *PathStorage

func (*PathStorage) Close 

func (p *PathStorage) Close() *PathStorage

func (*PathStorage) Copy 

func (src *PathStorage) Copy() (dest *PathStorage)

func (*PathStorage) CubicCurveTo 

func (p *PathStorage) CubicCurveTo(cx1, cy1, cx2, cy2, x, y float64) *PathStorage

func (*PathStorage) IsEmpty 

func (p *PathStorage) IsEmpty() bool

func (*PathStorage) LastPoint 

func (p *PathStorage) LastPoint() (x, y float64)

func (*PathStorage) LineTo 

func (p *PathStorage) LineTo(x, y float64) *PathStorage

func (*PathStorage) MoveTo 

func (p *PathStorage) MoveTo(x, y float64) *PathStorage

func (*PathStorage) QuadCurveTo 

func (p *PathStorage) QuadCurveTo(cx, cy, x, y float64) *PathStorage

func (*PathStorage) RArcTo 

func (p *PathStorage) RArcTo(dcx, dcy, rx, ry, startAngle, angle float64) *PathStorage

func (*PathStorage) RCubicCurveTo 

func (p *PathStorage) RCubicCurveTo(dcx1, dcy1, dcx2, dcy2, dx, dy float64) *PathStorage

func (*PathStorage) RLineTo 

func (p *PathStorage) RLineTo(dx, dy float64) *PathStorage

func (*PathStorage) RMoveTo 

func (p *PathStorage) RMoveTo(dx, dy float64) *PathStorage

func (*PathStorage) RQuadCurveTo 

func (p *PathStorage) RQuadCurveTo(dcx, dcy, dx, dy float64) *PathStorage

func (*PathStorage) String 

func (p *PathStorage) String() string

type StackGraphicContext 

type StackGraphicContext struct {
	Current *ContextStack
}

func NewStackGraphicContext 

func NewStackGraphicContext() *StackGraphicContext

*

  • Create a new Graphic context from an image

func (*StackGraphicContext) ArcTo 

func (gc *StackGraphicContext) ArcTo(cx, cy, rx, ry, startAngle, angle float64)

func (*StackGraphicContext) BeginPath 

func (gc *StackGraphicContext) BeginPath()

func (*StackGraphicContext) Close 

func (gc *StackGraphicContext) Close()

func (*StackGraphicContext) ComposeMatrixTransform 

func (gc *StackGraphicContext) ComposeMatrixTransform(Tr MatrixTransform)

func (*StackGraphicContext) CubicCurveTo 

func (gc *StackGraphicContext) CubicCurveTo(cx1, cy1, cx2, cy2, x, y float64)

func (*StackGraphicContext) GetFontData 

func (gc *StackGraphicContext) GetFontData() FontData

func (*StackGraphicContext) GetFontSize 

func (gc *StackGraphicContext) GetFontSize() float64

func (*StackGraphicContext) GetMatrixTransform 

func (gc *StackGraphicContext) GetMatrixTransform() MatrixTransform

func (*StackGraphicContext) IsEmpty 

func (gc *StackGraphicContext) IsEmpty() bool

func (*StackGraphicContext) LastPoint 

func (gc *StackGraphicContext) LastPoint() (float64, float64)

func (*StackGraphicContext) LineTo 

func (gc *StackGraphicContext) LineTo(x, y float64)

func (*StackGraphicContext) MoveTo 

func (gc *StackGraphicContext) MoveTo(x, y float64)

func (*StackGraphicContext) QuadCurveTo 

func (gc *StackGraphicContext) QuadCurveTo(cx, cy, x, y float64)

func (*StackGraphicContext) RArcTo 

func (gc *StackGraphicContext) RArcTo(dcx, dcy, rx, ry, startAngle, angle float64)

func (*StackGraphicContext) RCubicCurveTo 

func (gc *StackGraphicContext) RCubicCurveTo(dcx1, dcy1, dcx2, dcy2, dx, dy float64)

func (*StackGraphicContext) RLineTo 

func (gc *StackGraphicContext) RLineTo(dx, dy float64)

func (*StackGraphicContext) RMoveTo 

func (gc *StackGraphicContext) RMoveTo(dx, dy float64)

func (*StackGraphicContext) RQuadCurveTo 

func (gc *StackGraphicContext) RQuadCurveTo(dcx, dcy, dx, dy float64)

func (*StackGraphicContext) Restore 

func (gc *StackGraphicContext) Restore()

func (*StackGraphicContext) Rotate 

func (gc *StackGraphicContext) Rotate(angle float64)

func (*StackGraphicContext) Save 

func (gc *StackGraphicContext) Save()

func (*StackGraphicContext) Scale 

func (gc *StackGraphicContext) Scale(sx, sy float64)

func (*StackGraphicContext) SetFillColor 

func (gc *StackGraphicContext) SetFillColor(c color.Color)

func (*StackGraphicContext) SetFillRule 

func (gc *StackGraphicContext) SetFillRule(f FillRule)

func (*StackGraphicContext) SetFontData 

func (gc *StackGraphicContext) SetFontData(FontData FontData)

func (*StackGraphicContext) SetFontSize 

func (gc *StackGraphicContext) SetFontSize(FontSize float64)

func (*StackGraphicContext) SetLineCap 

func (gc *StackGraphicContext) SetLineCap(Cap Cap)

func (*StackGraphicContext) SetLineDash 

func (gc *StackGraphicContext) SetLineDash(Dash []float64, DashOffset float64)

func (*StackGraphicContext) SetLineJoin 

func (gc *StackGraphicContext) SetLineJoin(Join Join)

func (*StackGraphicContext) SetLineWidth 

func (gc *StackGraphicContext) SetLineWidth(LineWidth float64)

func (*StackGraphicContext) SetMatrixTransform 

func (gc *StackGraphicContext) SetMatrixTransform(Tr MatrixTransform)

func (*StackGraphicContext) SetStrokeColor 

func (gc *StackGraphicContext) SetStrokeColor(c color.Color)

func (*StackGraphicContext) Translate 

func (gc *StackGraphicContext) Translate(tx, ty float64)

type VertexAdder 

type VertexAdder struct {
	// contains filtered or unexported fields
}

func NewVertexAdder 

func NewVertexAdder(adder raster.Adder) *VertexAdder

func (*VertexAdder) NextCommand 

func (vertexAdder *VertexAdder) NextCommand(cmd VertexCommand)

func (*VertexAdder) Vertex 

func (vertexAdder *VertexAdder) Vertex(x, y float64)

type VertexCommand 

type VertexCommand byte

VertexCommand defines different commands to describe the vertex of a path. 

const (
	// VertexNoCommand does nothing
	VertexNoCommand VertexCommand = iota
	// VertexStartCommand starts a (sub)path
	VertexStartCommand
	// VertexJoinCommand joins the two edges at the vertex
	VertexJoinCommand
	// VertexCloseCommand closes the subpath
	VertexCloseCommand
	// VertexStopCommand is the endpoint of the path.
	VertexStopCommand
)

type VertexConverter 

type VertexConverter interface {
	NextCommand(cmd VertexCommand)
	Vertex(x, y float64)
}

VertexConverter allows to convert vertices.

type VertexMatrixTransform 

type VertexMatrixTransform struct {
	Next VertexConverter
	// contains filtered or unexported fields
}

this VertexConverter apply the Matrix transformation tr

func NewVertexMatrixTransform 

func NewVertexMatrixTransform(tr MatrixTransform, converter VertexConverter) *VertexMatrixTransform

func (*VertexMatrixTransform) NextCommand 

func (vmt *VertexMatrixTransform) NextCommand(command VertexCommand)

Vertex Matrix Transform

func (*VertexMatrixTransform) Vertex 

func (vmt *VertexMatrixTransform) Vertex(x, y float64)

Source Files

View all Source files

Directories

Path Synopsis
Package draw2dgl provides a graphic context that can draw vector graphics and text on OpenGL.
 Package draw2dgl provides a graphic context that can draw vector graphics and text on OpenGL.
Package draw2dpdf provides a graphic context that can draw vector graphics and text on pdf file with the gofpdf package.
 Package draw2dpdf provides a graphic context that can draw vector graphics and text on pdf file with the gofpdf package.
Package samples provides examples which can be used with different backends.
 Package samples provides examples which can be used with different backends.
android
Package android draws an android avatar.
 Package android draws an android avatar.
frameimage
Package frameimage centers a png image and rotates it.
 Package frameimage centers a png image and rotates it.
geometry
Package geometry draws some geometric tests.
 Package geometry draws some geometric tests.
gopher
Package gopher draws a gopher avatar based on a svg of: https://github.com/golang-samples/gopher-vector/
 Package gopher draws a gopher avatar based on a svg of: https://github.com/golang-samples/gopher-vector/
gopher2
Package gopher2 draws a gopher avatar based on a svg of: https://github.com/golang-samples/gopher-vector/
 Package gopher2 draws a gopher avatar based on a svg of: https://github.com/golang-samples/gopher-vector/
helloworld
Package helloworld displays multiple "Hello World" (one rotated) in a rounded rectangle.
 Package helloworld displays multiple "Hello World" (one rotated) in a rounded rectangle.
helloworldgl
Open an OpenGl window and display a rectangle using a OpenGl GraphicContext
 Open an OpenGl window and display a rectangle using a OpenGl GraphicContext
line
Package line draws vertically spaced lines.
 Package line draws vertically spaced lines.
linecapjoin
Package linecapjoin demonstrates the different line caps and joins.
 Package linecapjoin demonstrates the different line caps and joins.
postscript
Package postscript reads the tiger.ps file and draws it to a backend.
 Package postscript reads the tiger.ps file and draws it to a backend.
postscriptgl
Open a OpenGL window and display a tiger interpreting a postscript file
 Open a OpenGL window and display a tiger interpreting a postscript file

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