draw

package
Version: v0.9.0 Latest Latest
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Published: Mar 10, 2021 License: BSD-3-Clause Imports: 7 Imported by: 101

Documentation

Overview

Package draw provides types and functions to draw shapes on a vg.Canvas.

Index

Examples

Constants

View Source
const (
	// XLeft aligns the left edge of the text with the specified location.
	XLeft = text.XLeft
	// XCenter aligns the horizontal center of the text with the specified location.
	XCenter = text.XCenter
	// XRight aligns the right edge of the text with the specified location.
	XRight = text.XRight
)
View Source
const (
	// YTop aligns the top of of the text with the specified location.
	YTop = text.YTop
	// YCenter aligns the vertical center of the text with the specified location.
	YCenter = text.YCenter
	// YBottom aligns the bottom of the text with the specified location.
	YBottom = text.YBottom
)
View Source
const (
	PosLeft   = text.PosLeft
	PosBottom = text.PosBottom
	PosCenter = text.PosCenter
	PosTop    = text.PosTop
	PosRight  = text.PosRight
)

Position specifies the text position.

Variables

This section is empty.

Functions

func Formats

func Formats() []string

Formats returns the sorted list of registered vg formats.

func NewFormattedCanvas

func NewFormattedCanvas(w, h vg.Length, format string) (vg.CanvasWriterTo, error)

NewFormattedCanvas creates a new vg.CanvasWriterTo with the specified image format. Supported formats need to be registered by importing one or more of the following packages:

gonum.org/v1/plot/vg/vgeps // provides eps
gonum.org/v1/plot/vg/vgimg // provides png, jpg|jpeg, tif|tiff
gonum.org/v1/plot/vg/vgpdf // provides pdf
gonum.org/v1/plot/vg/vgsvg // provides svg
gonum.org/v1/plot/vg/vgtex // provides tex

func RegisterFormat

func RegisterFormat(name string, fn func(w, h vg.Length) vg.CanvasWriterTo)

RegisterFormat registers an image format for use by NewFormattedCanvas. name is the name of the format, like "jpeg" or "png". fn is the construction function to call for the format.

RegisterFormat panics if fn is nil.

Types

type BoxGlyph

type BoxGlyph struct{}

BoxGlyph is a glyph that draws a filled square.

func (BoxGlyph) DrawGlyph

func (BoxGlyph) DrawGlyph(c *Canvas, sty GlyphStyle, pt vg.Point)

DrawGlyph implements the Glyph interface.

type Canvas

type Canvas struct {
	vg.Canvas
	vg.Rectangle
}

A Canvas is a vector graphics canvas along with an associated Rectangle defining a section of the canvas to which drawing should take place.

func Crop

func Crop(c Canvas, left, right, bottom, top vg.Length) Canvas

Crop returns a new Canvas corresponding to the Canvas c with the given lengths added to the minimum and maximum x and y values of the Canvas's Rectangle. Note that cropping the right and top sides of the canvas requires specifying negative values of right and top.

Example (SplitHorizontal)
c := draw.New(vgimg.New(vg.Points(10), vg.Points(16)))

// Split c along a vertical line centered on the canvas.
left, right := SplitHorizontal(c, c.Size().X/2)
fmt.Printf("left:  %#v\n", left.Rectangle)
fmt.Printf("right: %#v\n", right.Rectangle)
Output:

left:  vg.Rectangle{Min:vg.Point{X:0, Y:0}, Max:vg.Point{X:5, Y:16}}
right: vg.Rectangle{Min:vg.Point{X:5, Y:0}, Max:vg.Point{X:10, Y:16}}
Example (SplitVertical)
c := draw.New(vgimg.New(vg.Points(10), vg.Points(16)))

// Split c along a horizontal line centered on the canvas.
bottom, top := SplitVertical(c, c.Size().Y/2)
fmt.Printf("top:    %#v\n", top.Rectangle)
fmt.Printf("bottom: %#v\n", bottom.Rectangle)
Output:

top:    vg.Rectangle{Min:vg.Point{X:0, Y:8}, Max:vg.Point{X:10, Y:16}}
bottom: vg.Rectangle{Min:vg.Point{X:0, Y:0}, Max:vg.Point{X:10, Y:8}}

func New

func New(c vg.CanvasSizer) Canvas

New returns a new (bounded) draw.Canvas.

func NewCanvas

func NewCanvas(c vg.Canvas, w, h vg.Length) Canvas

NewCanvas returns a new (bounded) draw.Canvas of the given size.

func (*Canvas) Center

func (c *Canvas) Center() vg.Point

Center returns the center point of the area

func (*Canvas) ClipLinesX

func (c *Canvas) ClipLinesX(lines ...[]vg.Point) (clipped [][]vg.Point)

ClipLinesX returns a slice of lines that represent the given line clipped in the X direction.

func (*Canvas) ClipLinesXY

func (c *Canvas) ClipLinesXY(lines ...[]vg.Point) [][]vg.Point

ClipLinesXY returns a slice of lines that represent the given line clipped in both X and Y directions.

func (*Canvas) ClipLinesY

func (c *Canvas) ClipLinesY(lines ...[]vg.Point) (clipped [][]vg.Point)

ClipLinesY returns a slice of lines that represent the given line clipped in the Y direction.

func (*Canvas) ClipPolygonX

func (c *Canvas) ClipPolygonX(pts []vg.Point) []vg.Point

ClipPolygonX returns a slice of lines that represent the given polygon clipped in the X direction.

func (*Canvas) ClipPolygonXY

func (c *Canvas) ClipPolygonXY(pts []vg.Point) []vg.Point

ClipPolygonXY returns a slice of lines that represent the given polygon clipped in both X and Y directions.

func (*Canvas) ClipPolygonY

func (c *Canvas) ClipPolygonY(pts []vg.Point) []vg.Point

ClipPolygonY returns a slice of lines that represent the given polygon clipped in the Y direction.

func (*Canvas) Contains

func (c *Canvas) Contains(p vg.Point) bool

Contains returns true if the Canvas contains the point.

func (*Canvas) ContainsX

func (c *Canvas) ContainsX(x vg.Length) bool

ContainsX returns true if the Canvas contains the x coordinate.

func (*Canvas) ContainsY

func (c *Canvas) ContainsY(y vg.Length) bool

ContainsY returns true if the Canvas contains the y coordinate.

func (*Canvas) DrawGlyph

func (c *Canvas) DrawGlyph(sty GlyphStyle, pt vg.Point)

DrawGlyph draws the given glyph to the draw area. If the point is not within the Canvas or the sty.Shape is nil then nothing is drawn.

func (*Canvas) DrawGlyphNoClip

func (c *Canvas) DrawGlyphNoClip(sty GlyphStyle, pt vg.Point)

DrawGlyphNoClip draws the given glyph to the draw area. If the sty.Shape is nil then nothing is drawn.

func (*Canvas) FillPolygon

func (c *Canvas) FillPolygon(clr color.Color, pts []vg.Point)

FillPolygon fills a polygon with the given color.

func (*Canvas) FillText

func (c *Canvas) FillText(sty TextStyle, pt vg.Point, txt string)

FillText fills lines of text in the draw area. pt specifies the location where the text is to be drawn.

func (*Canvas) SetLineStyle

func (c *Canvas) SetLineStyle(sty LineStyle)

SetLineStyle sets the current line style

func (*Canvas) StrokeLine2

func (c *Canvas) StrokeLine2(sty LineStyle, x0, y0, x1, y1 vg.Length)

StrokeLine2 draws a line between two points in the given Canvas.

func (*Canvas) StrokeLines

func (c *Canvas) StrokeLines(sty LineStyle, lines ...[]vg.Point)

StrokeLines draws a line connecting a set of points in the given Canvas.

func (*Canvas) X

func (c *Canvas) X(x float64) vg.Length

X returns the value of x, given in the unit range, in the drawing coordinates of this draw area. A value of 0, for example, will return the minimum x value of the draw area and a value of 1 will return the maximum.

func (*Canvas) Y

func (c *Canvas) Y(y float64) vg.Length

Y returns the value of x, given in the unit range, in the drawing coordinates of this draw area. A value of 0, for example, will return the minimum y value of the draw area and a value of 1 will return the maximum.

type CircleGlyph

type CircleGlyph struct{}

CircleGlyph is a glyph that draws a solid circle.

func (CircleGlyph) DrawGlyph

func (CircleGlyph) DrawGlyph(c *Canvas, sty GlyphStyle, pt vg.Point)

DrawGlyph implements the GlyphDrawer interface.

type CrossGlyph

type CrossGlyph struct{}

CrossGlyph is a glyph that draws a big X.

func (CrossGlyph) DrawGlyph

func (CrossGlyph) DrawGlyph(c *Canvas, sty GlyphStyle, pt vg.Point)

DrawGlyph implements the Glyph interface.

type GlyphDrawer

type GlyphDrawer interface {
	// DrawGlyph draws the glyph at the given
	// point, with the given color and radius.
	DrawGlyph(*Canvas, GlyphStyle, vg.Point)
}

A GlyphDrawer wraps the DrawGlyph function.

type GlyphStyle

type GlyphStyle struct {
	// Color is the color used to draw the glyph.
	color.Color

	// Radius specifies the size of the glyph's radius.
	Radius vg.Length

	// Shape draws the shape of the glyph.
	Shape GlyphDrawer
}

A GlyphStyle specifies the look of a glyph used to draw a point on a plot.

func (GlyphStyle) Rectangle

func (g GlyphStyle) Rectangle() vg.Rectangle

Rectangle returns the rectangle surrounding this glyph, assuming that it is drawn centered at 0,0

type LineStyle

type LineStyle struct {
	// Color is the color of the line.
	Color color.Color

	// Width is the width of the line.
	Width vg.Length

	Dashes   []vg.Length
	DashOffs vg.Length
}

LineStyle describes what a line will look like.

type PlainTextHandler

type PlainTextHandler = text.Plain

PlainTextHandler is a text/plain handler.

type PlusGlyph

type PlusGlyph struct{}

PlusGlyph is a glyph that draws a plus sign

func (PlusGlyph) DrawGlyph

func (PlusGlyph) DrawGlyph(c *Canvas, sty GlyphStyle, pt vg.Point)

DrawGlyph implements the Glyph interface.

type PyramidGlyph

type PyramidGlyph struct{}

PyramidGlyph is a glyph that draws a filled triangle.

func (PyramidGlyph) DrawGlyph

func (PyramidGlyph) DrawGlyph(c *Canvas, sty GlyphStyle, pt vg.Point)

DrawGlyph implements the Glyph interface.

type RingGlyph

type RingGlyph struct{}

RingGlyph is a glyph that draws the outline of a circle.

func (RingGlyph) DrawGlyph

func (RingGlyph) DrawGlyph(c *Canvas, sty GlyphStyle, pt vg.Point)

DrawGlyph implements the Glyph interface.

type SquareGlyph

type SquareGlyph struct{}

SquareGlyph is a glyph that draws the outline of a square.

func (SquareGlyph) DrawGlyph

func (SquareGlyph) DrawGlyph(c *Canvas, sty GlyphStyle, pt vg.Point)

DrawGlyph implements the Glyph interface.

type TextHandler

type TextHandler = text.Handler

type TextStyle

type TextStyle = text.Style

type Tiles

type Tiles struct {
	// Cols and Rows specify the number of rows and columns of tiles.
	Cols, Rows int
	// PadTop, PadBottom, PadRight, and PadLeft specify the padding
	// on the corresponding side of each tile.
	PadTop, PadBottom, PadRight, PadLeft vg.Length
	// PadX and PadY specify the padding between columns and rows
	// of tiles respectively..
	PadX, PadY vg.Length
}

Tiles creates regular subcanvases from a Canvas.

func (Tiles) At

func (ts Tiles) At(c Canvas, x, y int) Canvas

At returns the subcanvas within c that corresponds to the tile at column x, row y.

type TriangleGlyph

type TriangleGlyph struct{}

TriangleGlyph is a glyph that draws the outline of a triangle.

func (TriangleGlyph) DrawGlyph

func (TriangleGlyph) DrawGlyph(c *Canvas, sty GlyphStyle, pt vg.Point)

DrawGlyph implements the Glyph interface.

type XAlignment

type XAlignment = text.XAlignment

XAlignment specifies text alignment in the X direction. Three preset options are available, but an arbitrary alignment can also be specified using XAlignment(desired number).

type YAlignment

type YAlignment = text.YAlignment

YAlignment specifies text alignment in the Y direction. Three preset options are available, but an arbitrary alignment can also be specified using YAlignment(desired number).

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