docs/annotations.html

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  10
  11 <h2>dygraphs Annotations</h2>
  12
  13 <p>dygraphs lets you add annotations (markers) to individual points on your
  14 chart. These markers have a short bit of text or an icon that's displayed
  15 over the chart, plus a longer description that appears when you hover over
  16 them.</p>
  17
  18 <h3>Demo: Dow Jones Industrial Average</h3>
  19 <div id="dow_chart" style="width: 800px; height: 250px;"></div>
  20 <script type="text/javascript">
  21   // From http://www.econstats.com/eqty/eq_d_mi_3.csv
  22   stockchart = new Dygraph(
  23     document.getElementById('dow_chart'),
  24     "dow.txt",
  25     {
  26       showRoller: true,
  27       customBars: true,
  28       labelsKMB: true,
  29       labelsDivWidth: 300
  30     }
  31   );
  32
  33   stockchart.ready(function(g) {
  34     g.setAnnotations( [
  35     {
  36       series: "Real",
  37       x: "1929-08-15",
  38       shortText: "A",
  39       text: "1929 Stock Market Peak",
  40       cssClass: 'annotation'
  41     },
  42     {
  43       series: "Nominal",
  44       x: "1987-08-15",
  45       shortText: "B",
  46       text: "1987 Crash",
  47       cssClass: 'annotation'
  48     },
  49     {
  50       series: "Nominal",
  51       x: "1999-12-15",
  52       shortText: "C",
  53       text: "1999 (.com) Peak",
  54       cssClass: 'annotation'
  55     },
  56     {
  57       series: "Nominal",
  58       x: "2007-10-15",
  59       shortText: "D",
  60       text: "All-Time Market Peak",
  61       cssClass: 'annotation'
  62     }
  63     ] );
  64   });
  65 </script>
  66
  67 <h3>Adding Annotations</h3>
  68
  69 <p>There are two methods which are used to add, remove and modify annotations:</p>
  70
  71 <table class="thinborder">
  72 <tr>
  73   <td><code>setAnnotations(array)</code></td>
  74   <td>Set the list of annotations currently displayed. This overwrites
  75   existing annotations and redraws the dygraph.</td>
  76 </tr>
  77 <tr>
  78   <td><code>annotations</code></td>
  79   <td>Returns an array of the currently-displayed annotations.</td>
  80 </tr>
  81 </table>
  82
  83 <p>Calling <code>dygraph.setAnnotations(dygraph.annotations())</code> is a
  84 no-op: it simply causes the chart to refresh.</p>
  85
  86 <p>Let's say we have a simple chart and wish to add an annotation. Here's how:</p>
  87
  88   <div class="example" style="clear:both;">
  89     <div class="codeblock" style="float:left;width:400px;">
  90       <h3 style="text-align:center">HTML</h3>
  91   <pre>
  92 &lt;script type=&quot;text/javascript&quot;&gt;
  93   g = new Dygraph(
  94     document.getElementById(&quot;graphdiv&quot;),
  95     &quot;Date,Temperature\n&quot; +
  96     &quot;2008-05-07,75\n&quot; +
  97     &quot;2008-05-08,70\n&quot; +
  98     &quot;2008-05-09,80\n&quot;
  99   );
 100
 101   g.ready(function() {
 102     g.setAnnotations([
 103     {
 104       series: &quot;Temperature&quot;,
 105       x: &quot;2008-05-08&quot;,
 106       shortText: &quot;L&quot;,
 107       text: &quot;Coldest Day&quot;
 108     }
 109     ]);
 110   });
 111 &lt;/script&gt;
 112 </pre>
 113 </div>
 114
 115 <div class="codeoutput" style="float:left;">
 116   <h3 style="text-align:center">OUTPUT</h3>
 117   <div id="graphdiv" style="width: 350px; height: 250px;"></div>
 118   <script type="text/javascript">
 119     g = new Dygraph(
 120
 121       // containing div
 122       document.getElementById("graphdiv"),
 123
 124       // CSV or path to a CSV file.
 125       "Date,Temperature\n" +
 126       "2008-05-07,75\n" +
 127       "2008-05-08,70\n" +
 128       "2008-05-09,80\n"
 129     );
 130     g.ready(function() {
 131         g.setAnnotations([
 132         {
 133           series: "Temperature",
 134           x: "2008-05-08",
 135           shortText: "L",
 136           text: "Coldest Day"
 137         }
 138         ]);
 139     });
 140   </script>
 141 </div>
 142 </div>
 143
 144 <p style="clear:both">Annotations are JavaScript dictionaries. The <code>series</code> and <code>x</code> fields are required: they indicate which point the annotation should be attached to. If specified, <code>shortText</code> will appear on the annotation "flag". If you don't specify <code>shortText</code>, you can specify <code>icon</code> instead to display a small picture. The <code>text</code> parameter specifies hovertext. If you highlight the annotation and leave the mouse still, it will appear.</p>
 145
 146 <p>If you are using <a href="http://dygraphs.com/data.html#array">native format</a>, you need to pass in a numeric value for the <code>x</code> field. For a numeric x-axis, simply pass in the x-value of the data point on which you wish to attach the annotation. For a date axis, pass in <code>Date.parse('YYYY/MM/DD')</code>. This returns milliseconds since epoch for the date.</p>
 147
 148 <h3>Modifying Annotations</h3>
 149 <p>To remove or modify existing annotations, call the
 150 <code>annotations</code> method to get an array of annotations. Modify that
 151 array, then pass it back in to <code>setAnnotations</code>. For example, this
 152 code deletes the second annotation and changes the series to which the first
 153 is attached:</p>
 154
 155 <pre>
 156 var annotations = g.annotations();
 157 annotations.splice(1,1);  // remove the second annotation
 158 annotations[0].series = "Series 2";
 159 g.setAnnotations(annotations);  // causes a redraw
 160 </pre>
 161
 162 <p>For a more real-life example, see the <a
 163 href="tests/annotation.html">annotations demo</a></p>
 164
 165 <h3>Annotations and Data Sources</h3>
 166 <p>When you pass a URL as the data source to dygraphs, it must issue a request
 167 for the data before drawing the chart. This means that the chart data is not yet
 168 available immediately after you call <code>new Dygraph</code> and so the call to
 169 <code>g.setAnnotations</code> will fail. The best way around this is to use the
 170 <code>ready()</code> method:</p>
 171
 172 <pre>g = new Dygraph(div, "path/to/data.csv");
 173 g.ready(function() {
 174   // This is called when data.csv comes back and the chart draws.
 175   g.setAnnotations([
 176     &hellip;
 177   ]);
 178 });
 179 </pre>
 180
 181 <h3>Annotations property reference</h3>
 182 <p>These properties can all be set in the dictionary for an annotation. The use of each one is demonstrated on the <a href="tests/annotation.html">annotations demo</a> page.</p>
 183
 184 <table class="thinborder">
 185 <tr> <td><b>Property</b></td><td><b>Description</b></td> </tr>
 186 <tr><td><code>series</code></td> <td><i>Required</i> The name of the series to which the annotated point belongs.</td></tr>
 187 <tr><td><code>x</code></td><td><i>Required</i> The x value of the point. This should be the same as the value you specified in your CSV file, e.g. "2010-09-13".</td></tr>
 188 <tr><td><code>shortText</code></td><td>Text that will appear on the annotation's flag.</td></tr>
 189 <tr><td><code>text</code></td><td>A longer description of the annotation which will appear when the user hovers over it.</td></tr>
 190 <tr><td><code>icon</code></td><td>Specify in place of <code>shortText</code> to mark the annotation with an image rather than text. If you specify this, you must specify <code>width</code> and <code>height</code>.</td></tr>
 191 <tr><td><code>width</code></td><td>Width (in pixels) of the annotation flag or icon.</td></tr>
 192 <tr><td><code>height</code></td><td>Height (in pixels) of the annotation flag or icon.</td></tr>
 193 <tr><td><code>cssClass</code></td><td>CSS class to use for styling the annotation.</td></tr>
 194 <tr><td><code>tickHeight</code></td><td>Height of the tick mark (in pixels) connecting the point to its flag or icon.</td></tr>
 195 <tr><td><code>attachAtBottom</code></td><td>If true, attach annotations to the x-axis, rather than to actual points.</td></tr>
 196 <tr><td><code>clickHandler</code></td>    <td>See Handlers, below</td></tr>
 197 <tr><td><code>mouseOverHandler</code></td><td>See Handlers, below</td></tr>
 198 <tr><td><code>mouseOutHandler</code></td> <td>See Handlers, below</td></tr>
 199 <tr><td><code>dblClickHandler</code></td> <td>See Handlers, below</td></tr>
 200 </table>
 201
 202 <h3>Annotation event handlers</h3>
 203
 204 <p>dygraphs lets you attach event handlers to your annotations. These can be
 205 specified globally (for all annotations) or on a per-annotation basis:</p>
 206
 207 <table class="thinborder">
 208 <tr><td><b>Per-point field</b></td><td><b>Global option</b></td></tr>
 209 <tr><td><code>clickHandler</code></td>    <td><code>annotationClickHandler</code></td></tr>
 210 <tr><td><code>mouseOverHandler</code></td><td><code>annotationMouseOverHandler</code></td></tr>
 211 <tr><td><code>mouseOutHandler</code></td> <td><code>annotationMouseOutHandler</code></td></tr>
 212 <tr><td><code>dblClickHandler</code></td> <td><code>annotationDblClickHandler</code></td></tr>
 213 </table>
 214
 215 <p>These event handlers all take the same parameters:</p>
 216
 217 <pre>g.updateOptions( {
 218   annotationClickHandler: function(annotation, point, dygraph, event) {
 219     // ... access/modify annotation.series, annotation.x, ...
 220   }
 221 }); </pre>
 222
 223 <p>Again, check out the <a href="tests/annotation.html">annotations demo</a>
 224 for concrete examples of usage of all these handlers.</p>
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