An interactive Javascript Plotting Boilerplate

For plotting visual 2D data with Javascript and HTML canvas (in 2d-context).

This is a simple collection of useful functions I am repetitively using for visualizing 2D geometries. Basic features are

• adding elements like vertices, lines, vectors, triangles, curves, polygons, ellipses, images
• cofiguration of the canvas behavior (fullsize, interaction, raster)
• mouse interaction (zoom, pan, drag elements)
• keyboard interaction
• touch interaction for dragging vertices (desktop and mobile)

The compressed library has 91kb.

Install the package via npm

   $ npm i -g npm          # Updates your npm if necessary
   $ npm i plotboilerplate # Installs the package

The HTML file

For a full example see main-dist.html :

   <canvas id="my-canvas">
      Your browser does not support the canvas tag.
   </canvas>

   <!-- Optional: a helper to display the mouse/touch position -->
   <div class="info monospace">
      [<span id="cx">-</span>,<span id="cy">-</span>]
   </div>

The ‘info’ block is just for displaying the current mouse/touch coordinates.

The javascript

   var pb = new PlotBoilerplate( {
       canvas		: document.getElementById('my-canvas'),
       fullSize         : true
    } );

Add elements to your canvas

   // Create two points:
   //   The origin is at the visual center by default.
   var pointA = new Vertex( -100, -100 );
   var pointB = new Vertex( 100, 100 );
   pb.add( new Line(pointA,pointB) );

   // When point A is moved by the user
   //   then move point B in the opposite direction
   pointA.listeners.addDragListener( function(e) {
   	pointB.sub( e.params.dragAmount );
	pb.redraw();
   } );
   
   // and when point B is moved
   //   then move point A
   pointB.listeners.addDragListener( function(e) {
   	pointA.sub( e.params.dragAmount );
	pb.redraw();
   } );

Screenshot

And the simple demo is here

API

See API Documentation for details.

Typescript

   // Usage with Typescript could look like this
   import { PlotBoilerplate, Vertex, Line } from "plotboilerplate";

   window.addEventListener( 'load', () => {
    
       const pointA : Vertex = new Vertex( 100,-100);
       const pointB : Vertex = new Vertex(-100, 100);
       console.log( pointA, pointB );

       const line : Line = new Line( pointA, pointB );
    
       const pb : PlotBoilerplate = new PlotBoilerplate( {
   	   canvas     : document.getElementById('my-canvas'),
	   fullSize   : true
       } );
    
       pb.add( line );

   } );

A full working demo repository about the Usage with Typescript is here.

Examples and screenshots

See the demo

Feigenbaum bifurcation (logistic map)

For a detailed description of this plot see my Feigenbaum-plot mini-project

See the demo

And here is a tiny article about it

Perpendiducular point-to-line-distance demo

See the demo

Random-scripture demo

See the demo

Vector field test

See the demo

Simple circumcircles of walking triangles animation

See the demo

Interactive Delaunay triangulation and Voronoi diagram

See the demo

Walking triangle demo

See the demo

Simple tweening animation using the GSAP library

See the demo

Perpendiculars of a Bézier path

See the demo

Tracing a cubic Bézier spline (finding the tangent values for each vertex)

See the demo

Drawing pursuit curves (each point following one other point)

See the demo

Drawing leaf venations (approach inspired by bleeptrack, see Operation Mindfuck)

See the demo

Morley triangle

See the demo

Hobby Curve

See the demo

Urquhart graph / Relative Neighbourhood graph

See the demo

Convex Polygon Incircle

See the demo

Pattern Gradient

See the demo

Pattern Gradient, Variant

See the demo

Remember the Extrusion Generator? Here’s a refactored one

See the demo

Distance between point and Bézier curve

See the demo

Intersection of two circles (radical line)

See the demo

Multiple circle intersections and their outlines

See the demo

Initialization parameters

Example

 var pb = new PlotBoilerplate( {
  // HTMLElement | string
  //   Your canvas element in the DOM (required).
  canvas			: document.getElementById('my-canvas'),

  // boolean
  //   If set to true the canvas will gain full window size.
  fullSize              	: true,

  // boolean
  //   If set to true the canvas will gain the size of its parent
  //   container.
  // @overrides fullSize
  fitToParent           	: true,

  // float
  //   The initial zoom. Default is 1.0.
  scaleX                	: 1.0,
  scaleY                	: 1.0,

  // float
  //   The initial offset. Default is 0.0. Note that autoAdjustOffset=true overrides these values.
  offsetX                	: 0.0,
  offsetY                	: 0.0,

  // Specifies if the raster should be drawn.
  drawGrid                : true,

  // If set to true the background grid will be drawn rastered.
  rasterGrid              : true,

  // float
  //    The exponential limit for wrapping down the grid.
  //    (2.0 means: halve the grid each 2.0*n zoom step).
  rasterAdjustFactor    	: 2.0,

  // Draw a crosshair at (0,0).
  drawOrigin              : false,

  // boolean
  //   When set to true then the origin of the XY plane will
  //   be re-adjusted automatically (see the params
  //    offsetAdjust{X,Y}Percent for more).
  autoAdjustOffset      	: true,
  // float
  //   The x- and y- fallback position for the origin after
  //   resizing the canvas.
  offsetAdjustXPercent  	: 50,
  offsetAdjustYPercent  	: 50,

  // int
  //   The canvas size fallback if no automatic resizing
  //   is switched on.
  defaultCanvasWidth    	: 1024,
  defaultCanvasHeight   	: 768,

  // float
  //   Two scaling factors (width and height) upon the canvas size.
  //   In combination with cssScale{X,Y} this can be used to obtain
  //   sub pixel resolutions for retina displays.
  canvasWidthFactor     	: 1.0,
  canvasHeightFactor    	: 1.0,

  // float
  //   Visually resize the canvas using CSS transforms (scale).
  cssScaleX	       	        : 1.0,
  cssScaleY	       	        : 1.0,

  // boolean
  //   If set to true only cssScaleX applies for both dimensions.
  cssUniformScale               : true,

  // boolean
  //   When set to true (default) the canvas will try to use the display's pixel ratio.
  autoDetectRetina              : true,

  // string
  //   A background color (CSS string) for the canvas.
  backgroundColor       	: '#ffffff',

  // boolean
  //   Switch auto-redrawing on resize on/off (some applications
  //   might want to prevent automatic redrawing to avoid data
  //   loss from the drae buffer).
  redrawOnResize        	: true,

  // boolean
  //   Indicates if Bézier curve handles should be drawn (used for
  //   editors, no required in pure visualizations).
  drawBezierHandleLines 	: true,

  // boolean
  //   Indicates if Bézier curve handle points should be drawn.
  drawBezierHandlePoints 	: true,

  // function
  //   A callback function that will be triggered just before the
  //   draw function clears the canvas (before anything else was drawn).
  preClear              	: function() { console.log('before clearing the canvas on redraw.'); },
	
  // function
  //   A callback function that will be triggered just before the
  //   draw function starts.
  preDraw               	: function() { console.log('after clearing and before drawing.'); },

  // function
  //   A callback function that will be triggered right after the
  //   drawing process finished.
  postDraw              	: function() { console.log('after drawing.'); },

  // boolean
  //   Indicates if the application should handle mouse events for you.

  enableMouse           	: true,
  // boolean
  //   Indicates if the application should handle touch events for you.
  enableTouch           	: true,

  // boolean
  //   Indicates if the application should handle key events for you.
  enableKeys            	: true,

  // boolean
  //   Indicates if the application should handle mouse wheelevents for you.
  enableMouseWheel              : true,

  // Indicates if the SVG export should be enabled (default is true). 
  enableSVGExport               : true,

  // boolean
  //   Indicates if the application should use the experimental WebGL features.
  enableGL                      : false
 } );

Events

The Vertex class has basic drag event support:

 var vert = new Vertex(100,100);
 vert.listeners.addDragListener( function(e) {
   // e is of type Event.
   // You are encouraged to use the values in the object e.params
   console.log( 'vertex was dragged by: ',
   	        'x='+e.params.dragAmount.x,
	        'y='+e.params.dragAmount.y );
 } );

The e.params object

 {
  // The canvas that fired the event.
  element : [HTMLElement],
    
  // The event name.
  //   Default: 'drag'
  name : string,

  // The current drag position.
  pos : { x : number, y : number },

  // A mouse button indicator (if mouse event).
  //    0=left, 1=middle, 2=right
  button : number,

  // A flag indicating if event comes from left mouse button.
  leftButton : boolean,

  // A flag indicating if event comes from middle mouse button.
  middleButton : boolean,

  // A flag indicating if event comes from right mouse button.
  rightButton : boolean,

  // A mouse-down-position: position where the dragging
  //   started. This will not change during one drag process.
  mouseDownPos : { x : number, y : number },

  // The most recent drag position (position before
  //   current drag step).
  draggedFrom : { x : number, y : number },

  // True if this is a drag event (nothing else available the moment).
  wasDragged : boolean,

  // The x-y-amount of the current drag step.
  //   This is the difference between the recent drag step
  //   and the actual drag position.
  dragAmount : { x : number, y : number }
 }

Mouse, Keyboard and Touch interaction

• [SHIFT] + [Click] : Select/Deselect vertex
• [Y] + [Click]: Toggle Bézier auto-adjustment for clicked bézier path point
• [ALT or SPACE] + [Mousedown] + [Drag] : Pan the area
• [Mousewheel-up] : Zoom in
• [Mousewheel-down] : Zoom out
• Touch & move (1 finger): Move item
• Touch & move (2 fingers): Pan the area
• Touch & pinch: Zoom in/out

Minimize the package

The package is minimized with webpack. See the webpack.config.js file.

Install webpack

This will install the npm-webpack package with the required dependencies for you from the package.json file.

 $ npm install

Run webpack

This will generate the ./dist/plotboilerplate.min.js file for you from the sources code files in ./src/js/*.

 $ npm run webpack

Compile Typescript

The package is compiled with npm typescript. See the tsconfig.json file.

Run the typescript compiler

This is not yet finished; the old vanilla-JS files will soon be dropped and replaced by generated files, compiled from Typescript.

 $ npm run compile-typescript

There is also a sandbox script, compiling and running the typescript files inside your browser. Please note that due to performance reasons it is not recommended to use this in production. Always compile your typescript files for this purpose.

Todos

• Use a sorted map in the line-point-distance demo.
• The experimental WebGL support requires Color objects instead of color strings. Otherwise each color string will be parse on each roundtrip which is a nightmare for the performance.
• The Color.parse(string) function does only recognize HEX, RGB and RGBA strings. HSL is still missing. Required?
• Replace all color params: replace type string by color. (tinycolor?)
• Measure the canvas’ border when applying fitToParent! Currently a 1px border is expected.
• Implement snap-to-grid.
• Make ellipses rotatable.
• Write better viewport/viewbox export. Some viewers do not understand the current format. Refactor BoundingBox2 for this?
• Add arcs?
• Add image flipping.
• Add Images to the SVGBuiler.
• Add image/svg support (adding SVG images).
• Add a vertex attribute: visible. (to hide vertices).
• [Partially done] Add control button: set to retina resolution (size factors and css scale).
• Add a demo that draws a proper mathematical xy-grid.
• Extend the leaf venation generator demo.
• Add a thumbnail generator script for the screenshots (like with imagick).
• Add a retina detection; initialize the canvas with double resolution on startup if retina display (optional-flag).
• Change the behavior of Vector.intersection(…). The intersection should be on both vectors, not only on their line intersection!
• Rename drawutils class to Drawutils or DrawUtils. Repective name DrawUtilsGL.
• Use the new Bounds class in the RectSelector helper.
• Adapt the bounds in the RectSelector (use min:Vertex and max:Vertex).
• Build a feature for line-styles; each ‘color’ param could also be gradient or a pattern (stroked, dotted, dashed, … ). See ctx.setLineDash(…).
• Add an internal mapping to remember vertices and their installed listeners (for removing them later).
• Destroy installed vertex listeners from vertices after removing them (like the Bézier auto-adjuster).
• Port all demos from vanilla JS to TypeScript.
• Add a TouchHandler (such as the MouseHandler) to wrap AlloyFinger? Add this to the main demo to keep track of touch positions?
• Listeners using Vertex.listeners.addDragStopListener() are not triggered on touch events.
• IMPORTANT: replace Touchy by AlloyFinger also in the public main page.
• Add a removeVertices() function (and use it in the threejs demo).

Todos for future Version 2

• Change the Vector.inverse() function to reverse (or something). Currently this is not what the inverse of a vector should be.
• Change the bezier point path order from [start,end,startContro,endControl] to [start,startControl,endControl,end].
• Change BezierPath.getPointAt to .getVertexAt (or .getVertAt or vertAt?).
• Change BezierPath.scale( center, factor ) to BezierPath.scale( factor, center ) and make center optional (like in Polygon).
• Rename BezierPath.adjustCircular to .isCircular, because cirularity does not only affect vertex adjustment.
• The inverse-functions are called Vertex.inv() but Vector.inverse(). Harmonize this.
• CubicBezierCurve.getTangentAt(number) and .getTangent(number) return Vertex, why not a Vector?

Browsers support

IE / Edge	Firefox	Chrome	iOS Safari
IE11 & Edge	latest	latest	latest

Credits

• dat.gui
• Color.js
• FileSaver.js
• AlloyFinger.js
• Hobby-Curve quick implementation by Prof. Dr. Edmund Weitz, http://weitz.de/hobby/
• hobby.pdf
• jsHobby
• Blake Bowen’s Catmull-Rom demo
• mbostock for the great convex-polygon-incircle implementation
• and for circle-tangent-to-three-lines
• Circle Intersection in C++ by Robert King
• The ‘Circles and spheres’ article by Paul Bourke

Known bugs

• BezierPath counstructor (from an older implementation) fails. This needs to be refactored.
• SVG resizing does not work in Firefox (aspect ratio is always kept, even if clip box changes). Please use PNGs until this is fixed.
• The BBTree.iterator() fails if the tree is empty! (Demos)
• The minifid BBTree and BBTreeCollection files do not export anything. The un-minified to. Why that?
• Currently no more known. Please report bugs.

Basics

How to use the basic classes

Changelog

View changelog