Graphics

WLJS

Execution environment

wljs-graphics-d3

Package

Graphics[objects_, opts___]

represents a two-dimensional graphical image. This is a fundamental expression, which is produced by all 2D plotting functions

Graphics[
 Table[{Hue[t/20.0,1., 0.5], Circle[{Cos[2 Pi t/20], Sin[2 Pi t/20]}]}, {t, 20}]]

Graphics[{EdgeForm[Black], Green, Rectangle[{0, -1}, {2, 1}], Red, Disk[], Blue,
   Circle[{2, 0}], Yellow, Polygon[{{2, 0}, {4, 1}, {4, -1}}], Purple, Arrow[{{4, 3/2}, {0, 3/2}, {0, 0}}], Black, 
  SVGAttribute[Line[{{-1, 0}, {4, 0}}], "stroke-dasharray"->"3"]}]

The engine that interprets graphical data is a separate Javascript library (shipped together with WLJS Notebook).

Graphics[{{Red, Disk[{5, 5}, 4]}, 
  Raster[Table[{x, y, x, y}, {x, .1, 1, .1}, {y, .1, 1, .1}]]}]

Graphics objects

Please see the corresponding section in Reference section for expression to be used with Graphics.

Mostly all primitives are generated by a high-order functions like Plot, ListLinePlot, ListVectorPlot, BubbleChart and etc

Context symbols

Here is a list of utility symbols used in Graphics context

Graphics`Canvas

Is used to have an access to SVG container of Graphics function

Methods

EventHandler

Is used to capture various events such as

• "mousemove"
• "click"

For example

pt = {0,0};
Graphics[{
	EventHandler[Graphics`Canvas[], {
		"mousemove" -> Function[xy, pt = xy]
	}], Red,
	Circle[pt // Offload, 0.08]
}, PlotRange->{{-1,1}, {-1,1}}]

tip

See more in Mouse and keyboard

Graphics`DPR

Returns device density pixel ratio (for retina-like displays it is more than 1.0). It comes handy when working with raster graphics - Image placed on graphics canvas.

FrontFetch[Graphics`DPR]

Evaluate it on the frontend using FrontFetch or FrontFetchAsync like functions.

Options

PlotRange

manually specifies, where the borders of the visible area (viewport) are

PlotRange->{{-1,1}, {-1,1}}

note

If PlotRange is missing, WLJS Graphics will try to guess the dimensions in order to fit all objects to the screen

ImageSize

specifies the actual size in pixels of a canvas

ImageSize->300 or ImageSize->{300,200}

ImagePadding

removes or adds the spacing between the plotted range and the canvas border

remove any padding

ImagePadding->None

add to all sides

ImagePadding->10

PlotLabel

Specifies a label for a plot

Plot[Sin[x], {x, 0, 10}, PlotLabel -> Offset["Sin[x]", {0,-1}], LabelStyle -> Directive[Orange, FontSize->14]]

can be used with Offset as well

Axes

Show or hide axes

Axes->True

Example

Graphics[{EdgeForm[Black], Green, Rectangle[{0, -1}, {2, 1}], Red, Disk[], Blue,
   Circle[{2, 0}], Yellow, Polygon[{{2, 0}, {4, 1}, {4, -1}}], Purple, Arrow[{{4, 3/2}, {0, 3/2}, {0, 0}}], Black, 
  SVGAttribute[Line[{{-1, 0}, {4, 0}}], "stroke-dasharray"->"3"]}, Axes->True ]

AxesLabel

Place labels on your axes

AxesLabel -> {"xxx", "yyy"}

note

Activate Axes option first

for example

Labels accepts only strings or numbers unlike Mathematica, where you can put everything.

Since it is translated into Text, one can use sort of TeX math input

Graphics[Circle[], Axes->True, AxesLabel -> {"x-axis (cm^{-1})", "y-axis \\alpha"}]

It also supports Offset attribute

Graphics[Circle[], Axes->True, AxesLabel -> {Offset["x-axis (cm^{-1})", {0,0.5}], "y-axis \\alpha"}]

Ticks

Customize ticks by providing an array of numbers for both axes

Graphics[Circle[], Axes->True, Ticks->{{0, 0.5, 1}, {}}]

Or by providing as pairs {Number, String} one can specify the displayed text

Graphics[Circle[], Axes->True, Ticks->{{{0, "Zero"}, {0.5, "Half"}, {1,"One"}}, {}}]

Controls

The features allows to pan and zoom your plots, that was never possible in Mathematica

Controls->True

Try to use your mouse here

note

from the latest update, this is True by the default

Frame

Turns plot into the journals-like styled graph. In general it has much more options to customize the look

Graphics[Circle[], Axes->True, Frame->True]

FrameTicks

The same as Ticks, but for this regime.

FrameLabel

The same as AxesLabel

FrameLabel->{{"yy", None}, {"xx", None}}

to specify an absolute offset for each label, provide a list instead of a string

FrameLabel->{{{"yy", {xoffset, yoffset}}, None}, {"xx", None}}

FrameStyle

Affects the style of FrameLabels. Use Directive for changing the style

FrameStyle->Directive[FontSize->16]

FrameTicksStyle

Affects the style of FrameTicks

FrameTicksStyle->Directive[FontSize->16]

TickLabels

To remove unnecessary ticks, use

TickLabels->{{True, False}, {True, False}}

Epilog

Puts any graphics object on top

Epilog->{Red, Line[{{-1,-1}, {1,1}}]}

It opens up many possibilities, since it provides low-level access to the Graphics canvas.

Example

One can use it on a high-level function like Plot to add low-level primitives

Plot[Sin[x], {x,0,Pi}, Epilog->{Red, Line[{{-1,-1}, {1,1}}]}]

or together with FrontInstanceReference

Prolog

The same as Epilog, but acts before plotting the data.

TransitionType

See Dynamics. The possible values

info

It can also be applied locally, see TransitionType

"Linear"

THE DEFAULT ONE

For example

cell 1

pt = {-1,0};
Graphics[{PointSize[0.3], Point[pt // Offload]}, ImageSize->350, PlotRange->{{-1,1}, {-1,1}}, "TransitionType"->"Linear"]

cell 2

pt = RandomReal[{-1,1}, 2];

"CubicInOut"

This one is used by the default

cell 1

pt = {-1,0};
Graphics[{PointSize[0.3], Point[pt // Offload]}, ImageSize->350, PlotRange->{{-1,1}, {-1,1}}, "TransitionType"->"CubicInOut"]

None

No transition. Works great for fast animations

TransitionDuration

Sets the duration of any transitions of graphics objects on canvas in milliseconds. The default value is 300.

info

It can also be applied locally, see TransitionDuration

Combining two graphics plots

One can put Graphics into another Graphics canvas using [[frontend/Reference/Graphics/Inset]]

Dynamics

The time-dependent symbols (Dynamics) are supported on the level of graphics primitives such as Line, Point, Rectangle, Text and etc... Not all primitives do support dynamic updates, please, check individually.

The full reevaluation of Graphics does not happen, that allows to gain much more performance. However, since the dynamic binding is established between individual primitives and symbols, one can make nested constructions like this one

radius = 1.;
angle = 0.;
tpos = 0.

group = {
  LightBlue, Disk[{0,0}, radius // Offload],
  LightBlue, AbsoluteThickness[25], Line[{{-1,1}, {1,-1}}],
  Red, Directive[FontSize->24],
  Text["Hello World", {Offload[-0.23 + tpos],0}]
};

Graphics[Rotate[group, angle // Offload], TransitionType->"Linear", TransitionDuration->100]

Here

• an update of angle will not cause reevaluation of group
• and update of radius will only update the radius of Disk
• and update of tpos will reevaluate an expression -0.23 + tpos and change the text position

Let us animate this example

evaluate in a separate cell

Do[
  radius = 1+0.5 Sin[x];
  tpos = 0.5 Cos[4x];
  angle = x;
  Pause[0.1];
, {x, 0. , 2Pi, 0.1}];

The result will look like

Supported output forms

• StandardForm
• WLXForm