simpledraw-7a.svg

<svg xmlns="http://www.w3.org/2000/svg"
     xmlns:xlink="http://www.w3.org/1999/xlink"
     width="100%" height="100%" viewBox="0 0 600 600">

  <title>SimpleDraw</title>

  <script type="text/ecmascript"><![CDATA[
    window.onload = function () {
      var dnd = new simpledrawObj();
      dnd.init();
    }

    function simpledrawObj() {
      this.root = document.documentElement;
      this.backdrop = document.getElementById("backdrop");
      this.canvas = document.getElementById("canvas");

      this.activeEl = null;

      this.buttons = null;
      this.mode = "draw-dot";

      this.coords = document.documentElement.createSVGPoint();
      this.originpoint = document.documentElement.createSVGPoint();

      // constants
      this.svgns = "http://www.w3.org/2000/svg";
      this.xlinkns = "http://www.w3.org/1999/xlink";
    }

    simpledrawObj.prototype.init = function (event){
      this.root.addEventListener('click', bind(this, this.draw), false );

      this.root.addEventListener('mousedown', bind(this, this.grab), false );
      this.root.addEventListener('mousemove', bind(this, this.drag), false );
      this.root.addEventListener('mouseup', bind(this, this.drop), false );

      this.buttons = this.root.querySelectorAll("[role='button']");
      for (var b = 0, bLen = this.buttons.length; bLen > b; ++b) {
        var eachButton = this.buttons[b];
        eachButton.addEventListener('click', bind(this, this.handleButtons), false );
      }
    }


    /*
    // draw
    */
    simpledrawObj.prototype.draw = function (event){
      if ( this.backdrop == event.target || this.canvas == event.target.parentNode ) {
        // adjust coords
        this.coords = localCoords(event, this.backdrop);

        switch (this.mode) {
          case "draw-dot":
            this.drawDot(event);
            break;

          case "draw-polyline":
            this.drawPolyline(event);
            break;

          case "draw-polygon":
            this.drawPolygon(event);
            break;

        }
      }
    }

    simpledrawObj.prototype.drawDot = function (event){
      this.activeEl = document.createElementNS(this.svgns, "circle");
      this.activeEl.setAttribute("cx", this.coords.x);
      this.activeEl.setAttribute("cy", this.coords.y);
      this.activeEl.setAttribute("r", "2");
      this.activeEl.setAttribute("fill", "none");
      this.activeEl.setAttribute("stroke", "blue");
      this.activeEl.setAttribute("stroke-width", "3");
      this.activeEl.setAttribute("stroke-linecap", "round");
      this.activeEl.setAttribute("stroke-linejoin", "round");

      // note that we're now appending draw elements to a specific canvas
      this.canvas.appendChild( this.activeEl );

      // if we don't set this to null, it starts dragging immediately!
      this.activeEl = null;
    }

    simpledrawObj.prototype.drawPolyline = function (event){
      if (! this.activeEl 
          || "polyline" != this.activeEl.localName ) {
        this.activeEl = document.createElementNS(this.svgns, "polyline");
        var style = "fill:cornflowerblue; ";
        style += "stroke:cornflowerblue; ";
        style += "stroke-width:1px; ";
        style += "stroke-linecap:round; ";
        style += "stroke-linejoin:round; ";
        style += "fill-opacity:0.5; ";
        this.activeEl.setAttribute("style", style);
      }

      var points = this.activeEl.getAttribute("points");
      if (!points) {
        points = "";
      }
      points += this.coords.x + "," + this.coords.y + " ";
      this.activeEl.setAttribute("points", points);

      if ( this.canvas != event.target.parentNode ) {
        this.canvas.appendChild( this.activeEl );
      }
    }

    simpledrawObj.prototype.drawPolygon = function (event){
      if (! this.activeEl 
          || "polygon" != this.activeEl.localName ) {
        this.activeEl = document.createElementNS(this.svgns, "polygon");
        var style = "fill:crimson; ";
        style += "stroke:crimson; ";
        style += "stroke-width:1px; ";
        style += "stroke-linecap:round; ";
        style += "stroke-linejoin:round; ";
        style += "fill-opacity:0.5; ";
        this.activeEl.setAttribute("style", style);
      }

      var points = this.activeEl.getAttribute("points");
      if (!points) {
        points = "";
      }
      points += this.coords.x + "," + this.coords.y + " ";
      this.activeEl.setAttribute("points", points);

      if ( this.canvas != event.target.parentNode ) {
        this.canvas.appendChild( this.activeEl );
      }
    }


    /*
    // drag-n-drop
    */
    simpledrawObj.prototype.grab = function (event){
      if ( "drag" == this.mode ){
        // stop native drag-n-drop
        event.preventDefault();
        event.stopPropagation();

        // only grab things in drawing area
        if ( this.canvas == event.target.parentNode ) {
          var target = event.target;
          if (this.backdrop != target) {
            this.activeEl = target;

            this.coords = localCoords(event, this.backdrop);
            this.originpoint = this.coords;
          }
        }
      } 
    }

    simpledrawObj.prototype.drag = function (event){
      if ( "drag" == this.mode ){
        if ( this.activeEl ) {
          this.coords = localCoords(event, this.backdrop);
          var x = this.coords.x - this.originpoint.x;
          var y = this.coords.y - this.originpoint.y;

          this.activeEl.setAttribute("transform", "translate(" + x + "," + y + ")");
        }
      }
    }

    simpledrawObj.prototype.drop = function (event){
      if ( "drag" == this.mode ){
        this.activeEl = null;
      }
    }


    /*
    // UI controls
    */
    simpledrawObj.prototype.handleButtons = function (event){
      // clicking on any button should start a new active element and new mode
      this.activeEl = null;

      for (var b = 0, bLen = this.buttons.length; bLen > b; ++b) {
        var eachButton = this.buttons[b];
        eachButton.setAttribute("aria-pressed", "false" );
      }

      var target = event.target.parentNode;
      target.setAttribute("aria-pressed", "true" );
      this.mode = target.getAttribute("data-mode");
      
      console.log("mode: " + this.mode);
    }


    // adjust coordinates for transforms
    function localCoords ( event, element ) {
      var p = document.documentElement.createSVGPoint();
      p.x = event.clientX;
      p.y = event.clientY;
      return p.matrixTransform(element.getScreenCTM().inverse());
    }   

    function bind (scope, fn) {
      return function () {
        return fn.apply( scope, arguments );
      }
    }


  ]]></script>


  <style>
    *[role="button"] {
      stroke: indigo;
      fill: violet;
      stroke-width: 1px;
    }

      *[role="button"] text {
        font-size: 12px;
        font-family: Verdana, sans-serif;
        text-anchor: middle;
        stroke: none;
        fill: indigo;
        pointer-events: none;
      }

      *[aria-pressed="true"] rect {
        stroke-width: 3px;
      }

    svg#canvas {
      pointer-events: all;
    }

    rect#backdrop {
      fill: url(#grid100);
      stroke: gray;
    }

    /*
    rect {
      shape-rendering: geometricPrecision;
    }
    */
  </style>


  <defs>
    <pattern id="grid10" x="0" y="0" width="10" height="10" patternUnits="userSpaceOnUse">
      <rect x="0" y="0" width="10" height="10" style="stroke:gray;stroke-width:.1;fill:none;"/>
    </pattern>

    <pattern id="grid100" x="0" y="0" width="100" height="100" patternUnits="userSpaceOnUse">
      <rect x="0" y="0" width="100" height="100" style="stroke:gray;stroke-width:0.2;fill:url(#grid10);"/>
    </pattern>
  </defs>


  <rect id="backdrop" x="0" y="0" width="600" height="600"/>

  <svg id="canvas" x="0" y="0" width="100%" height="100%">
    
  </svg>

  <g id="controls" transform="translate(10,10)">
    <g id="button-drawdot" role="button" aria-pressed="true" data-mode="draw-dot">
      <rect x="0" y="0" width="100" height="20" rx="3" ry="3"/>
      <text x="50" y="15">Draw Dot</text>
    </g>

    <g id="button-drawpolyline" transform="translate(0,30)" role="button" aria-pressed="false" data-mode="draw-polyline">
      <rect x="0" y="0" width="100" height="20" rx="3" ry="3"/>
      <text x="50" y="15">Draw Polyline</text>
    </g>

    <g id="button-drawpolygon" transform="translate(0,60)" role="button" aria-pressed="false" data-mode="draw-polygon">
      <rect x="0" y="0" width="100" height="20" rx="3" ry="3"/>
      <text x="50" y="15">Draw Polygon</text>
    </g>

    <g id="button-drag" transform="translate(0,100)" role="button" aria-pressed="false" data-mode="drag">
      <rect x="0" y="0" width="100" height="20" rx="3" ry="3"/>
      <text x="50" y="15">Drag</text>
    </g>
  </g>


</svg>