From 770ba5201f5c60b2bb36602ff9d359f641e33125 Mon Sep 17 00:00:00 2001 From: Yves Fischer Date: Sun, 23 Oct 2011 21:14:40 +0200 Subject: Charting with flask, rgraph and custom "timeseries database" --- schall/static/RGraph/docs/misc.html | 843 ++++++++++++++++++++++++++++++++++++ 1 file changed, 843 insertions(+) create mode 100644 schall/static/RGraph/docs/misc.html (limited to 'schall/static/RGraph/docs/misc.html') diff --git a/schall/static/RGraph/docs/misc.html b/schall/static/RGraph/docs/misc.html new file mode 100644 index 0000000..9711912 --- /dev/null +++ b/schall/static/RGraph/docs/misc.html @@ -0,0 +1,843 @@ + + + + + + RGraph: HTML5 Javascript charts library - Miscellaneous + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
+ + Mention RGraph on Twitter + +
+ + + +
+ + +
+ + + + +

RGraph: HTML5 Javascript charts library - Miscellaneous documentation

+ + + + + + +
 
 
+

Canvas fallback content and visually impaired users

+ +

+ When using the canvas element you should be aware of the accessibility of your charts, for example where vision limited users are + concerned. Screen readers, for example, may not be able to convert a chart into something that is reasonable, so you should + consider + doing this yourself, possibly using the canvas fallback content (ie the content in between the canvas tags). A possible example + would be to put a table of data inside the canvas tag that the chart on the canvas represents. Doing this goes a long way + towards making the data available to everyone. You might also wish to consider using the full canvas + zoom or the resizing feature to enable people to enlarge the chart. +

+ + +
 
 
+

Upper and lower limits for horizontal bars

+ +

+ If you don't wish to specify an upper or lower limit for horizontal bars, and you just want them to extend to the upper or lower + limits of the chart, whatever they may be, you can specify null for the value determining how far they extend. For cases where + the X axis is in the middle and you're specifying a negative start value, or you want the bar to extend all the way to the + bottom, you can simply specify an arbitrary length (eg -999999). Eg: +

+ + 
myBar.Set('chart.background.hbars', [[0, null, 'green'], [0,-999999,'red']]);
+ + +
 
 
+

Setting the canvas width and height

+ +

+ To set the canvas width and height you must use the HTML width/height attributes and NOT CSS. If you do use CSS, the canvas + will be scaled, and not enlarged, to fit the new width/height. Eg: +

+ + 
<canvas id="myCanvas" width="200" height="100">[No canvas support]<canvas>
+ +

+ Note: + When you resize the canvas using CSS, not only will it be scaled (not enlarged), but it will also NOT be cleared. You can + see this effect on the animation page with the jQuery animation example. +

+ + +
 
 
+

The canvas coordinate system

+

+ The canvas coordinate system starts in the top left of the canvas (at [0,0] - the X value increasing as you go right + and the Y value as you go down), much like the CSS coordinates for the entire page. The + gutter goes around the canvas (ie top/bottom/left/right - where the labels and titles are placed), and the actual chart + sits in the middle. +

+ + +
 
 
+

RGraph and older browsers

+ +

+ Older versions of browsers are supported (assuming they have canvas support), however, if they don't support the canvas text + or shadow APIs these will naturally be unavailable. The charts will still be drawn, though without shadows or text. +

+ + +
 
 
+

RGraph and Microsoft Internet Explorer

+ +

+ You can now use RGraph with Internet Explorer 8 in conjunction with ExCanvas, (which brings a degree of <canvas> support to MSIE). + Bear in mind though that shadows are not available and thus are simulated. Microsoft Internet Explorer 9 has native <canvas> + support. +

+ + +
 
 
+ +

Debugging tips

+ +

+ If you're having a hard time debugging your chart, try these: +

+ + + + + + +
 
 
+

Inspecting an RGraph chart

+ +

+ To help when debugging your RGraph charts and canvas elements, you can use you browsers built in debugging tools. + An example is the WebKit developer tools which are available in Google Chrome and Apple Safari. There is a screenshot + of these tools (in docked mode) here. To view these + tools in Google Chrome press CTRL+SHIFT+J. Inspect the canvas, and then the associated object can be found via + the __object__ property. +

+ + + +
 
 
+

Double click context menus

+ +

+ Windows Opera, Windows Safari, Mac Safari and Mac Firefox all attach the context menu to the double click event (left mouse button), + not the right, in order to make it more reliable. +

+ + + +
 
 
+

Adding your own event handlers

+ +

+ Because each RGraph object exposes the canvas element (the same as what you get from document.getElementById()), + you can use normal procedures to add your own event handlers. Eg If you wanted to add your own onclick handler you could + do this: +

+ + 
+<script>
+    var myBar = new RGraph.Bar('cvs', [7,4,2,6,3,4,8]);
+    myBar.Draw();
+
+    myBar.canvas.onclick = function ()
+    {
+    }
+</script>
+
+

+ But what if, for example, you're using an RGraph feature which + uses the event handler that you need? In this case you can use the standard DOM2 method addEventListener(). This will add + your new event handler without replacing any existing one (ie the one installed by RGraph). For example: +

+ + 
+<script>
+    var myBar = new RGraph.Bar('cvs', [7,4,2,6,3,4,8]);
+    myBar.Draw();
+
+    function myFunc ()
+    {
+    }
+
+    myBar.canvas.addEventListener('click', myFunc, false)
+</script>
+
+ + + +
 
 
+

Carriage returns and newlines in labels

+ +

+ You can put carriage returns in your labels by using the string \r\n. This means your labels will span multiple lines. + Like so: +

+ + 
myBar.Set('chart.labels', 'John\r\n(Winner!)', ...)
+ + + +
 
 
+

Character set issues

+ +

+ If you're seeing strange, unrecognised characters in your text labels or titles, you may need to specify the correct + character set that the browser should use. In PHP you can do this with the header() function (which, as the + name suggests, sends a HTTP header): +

+ + 
<?php
+    header("Content-Type: text/html; charset=ISO-8859-1");
+?>
+ +

+ If you use Apache, you could use the header directive, though this may be overridden by other directives, + eg AddDefaultCharset. +

+ + +
 
 
+

How to identify an RGraph object

+ +

+ Because identity can sometimes be a tricky affair, there are a few RGraph properties that you can use to check whether an object + is an RGraph object: +

+ + + + + + + + + + + + +
 
 
+

Static Y axis

+ + +
+ + +
+ +
+
+ + + + A static Y axis is useful if you have a wide chart but limited space. Whilst not part of the RGraph libraries itself, it can be + achieved with a little HTML, like the chart shown. The HTML and the script to achieve this is shown below. + It involves placing an extra canvas above the chart with the Y axis drawn on it. This canvas doesn't + move when the main canvas scrolls left and right. + +

+ + Note: Because Firefox doesn't support the event.offsetX and event.offsetY properties and they have to be simulated, + scrolling in conjunction with tooltips in this case and this browser doesn't work. + + 

+<div style="position: relative; float: right; margin-right: 10px; margin-top: 10px">
+    <!-- The width here is set further down the page in script -->
+    <canvas id="axes" width="0" height="200" style="position: absolute; top: 0; left: 0; z-index: 100"></canvas>
+    <div style="width: 600px; overflow: auto">
+        <canvas id="cvs" width="1000" height="200"></canvas>
+    </div>
+</div>
+
+<script>
+    window.onload = function ()
+    {
+        /**
+        * This is the script that draws the chart
+        */
+        line = new RGraph.Line('cvs', [3,15,22,26,28,24,22,25,23,24,26,23,24,25,27,28,29,26,23,22,24,21,24,25]);
+        line.Set('chart.noaxes', true); // We draw the Y axis ourselves
+        line.Set('chart.gutter.top', 25);
+        line.Set('chart.gutter.bottom', 35);
+        line.Set('chart.gutter.left', 50);
+        line.Set('chart.hmargin', 5);
+        line.Set('chart.linewidth', 3);
+        line.Set('chart.shadow', true);
+        line.Set('chart.shadow.offsetx', 0);
+        line.Set('chart.shadow.offsety', 0);
+        line.Set('chart.shadow.blur', 15);
+        line.Set('chart.shadow.color', 'red');
+        line.Set('chart.text.angle', 15);
+        line.Set('chart.tooltips', [
+                                    'January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December',
+                                    'January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'
+                                   ]);
+        line.Set('chart.labels', [
+                                  '','Feb 09', 'Mar 09','Apr 09','May 09','Jun 09','Jul 09','Aug 09','Sep 09','Oct 09','Nov 09', 'Dec 09',
+                                  'Jan 10', 'Feb 10', 'Mar 10','Apr 10','May 10','Jun 10','Jul 10','Aug 10','Sep 10','Oct 10','Nov 10', 'Dec 10'
+                                 ]);
+        line.Draw();
+
+
+
+        /**
+        * And this is the script that draws the left axis, on the other canvas (that doesn't move)
+        */
+        ca = document.getElementById("axes")
+        co = ca.getContext('2d');
+
+
+        /**
+        * This sets the smaller canvas to cover the whole of the charts left gutter
+        */
+        ca.width = line.Get('chart.gutter.left') + 1;
+
+
+        RGraph.Clear(ca, 'white');
+
+
+        /**
+        * This draws the static axis
+        */
+        co.beginPath();
+            co.moveTo(line.Get('chart.gutter.left'), line.Get('chart.gutter.top'));
+            co.lineTo(line.Get('chart.gutter.left'), line.canvas.height - line.Get('chart.gutter.bottom'));
+
+            // Draw the tickmarks on the axis
+            var numTicks = 10;
+            for (var i=0; i<=numTicks; ++i) {
+                co.moveTo(line.Get('chart.gutter.left'), line.Get('chart.gutter.top') + (((ca.height - line.Get('chart.gutter.top') - line.Get('chart.gutter.bottom')) / numTicks) * i));
+                co.lineTo(line.Get('chart.gutter.left') - 3, line.Get('chart.gutter.top') + (((ca.height - line.Get('chart.gutter.top') - line.Get('chart.gutter.bottom')) / numTicks) * i));
+            }
+
+        co.stroke();
+
+
+
+        /**
+        * This draws the labels for the static axis
+        */
+        co.beginPath();
+            var color = 'black';
+            var size = 10;
+
+            for (var i=0; i<5; ++i) {
+                co.fillStyle = color;
+                co.textAlign = 'right';
+                co.textBaseline = 'middle';
+                var h = line.canvas.height - line.Get('chart.gutter.top') - line.Get('chart.gutter.bottom');
+
+                RGraph.Text(co,
+                            'Verdana',
+                            size,
+                            line.Get('chart.gutter.left') - 4,
+                            line.Get('chart.gutter.top') + (h * (i/5)),
+                            line.max - (line.max * (i/5)));
+            }
+        co.fill();
+    }
+</script>
+
+ + + +
+
+ + + + + +
 
 
+

Reducing white space

+ + + + + +

+ New in June 2011 is the ability to set the gutters independently. This removes the necessity to translate + and adjust the coordinates to get more space and is far more straight-forward. The new properties are: + +

+ + You can read more about this change here. +

+ + +
+ + + +
 
 
+

In-graph labels

+ +

+ As well as an array of strings, like this: +

+ + 
obj.Set('chart.labels.ingraph', ['First label','Second label']);
+ +

+ The string can also be an array, consisting of color and placement information, like this: +

+ + 
obj.Set('chart.labels.ingraph', ['First label',['Second label', 'red', 'yellow', -1, 50] ]);
+ + +

+ You can read more information about this here. +

+ + +
 
 
+

Shorthand for in-graph labels

+

+ Instead of providing a full array of null elements for in-graph labels which may get a little unwieldy, + you can instead specify an integer that specifies how many elements to skip. Like this: +

+ + 
line.Set('chart.labels.ingraph', [6, 'July', 3, 'November']);
+ +
+
+ + +
 
 
+

DOM2 Event handlers

+

+ All the charts have now (1st October 2010) been converted to DOM2 for tooltips event registration. This allows them to + be far more co-operative if you're using events. Tooltips will not be compatible with MSIE8 - the charts will still be + drawn, albeit without tooltips. +

+ + + +
+ + + + + +
 
 
+

Data types

+

+ If your data values aren't the correct type - ie numbers - it can cause problems. Pay particular attention to this + when you're getting your data from data sources which may be classed as strings, such as JSON or AJAX requests. +

+ + + + + +
 
 
+

Creating your own chart type

+

+ If you wish to create your own chart type, there is a skeleton file + here that you can use as a starting point. + This file contains the bare bones of an RGraph object, such as the .Get() and .Set() methods, as well as examples + of common properties. +

+ + + +
 
 
+

World map

+

+ There is no function in RGraph to do mapping, either of the World or a smaller region. If this is what you want then you + may be interested in this HTML5 canvas based mapping system: + http://joncom.be/code/excanvas-world-map/ +

+ + + +
 
 
+

Adding text to your charts

+

+ You can add arbitrary text to your charts by using the RGraph API. For example you could use this code after the call to .Draw(): +

+ + 
+function DrawSubTitle (obj)
+{
+    var context = obj.context;
+    
+    context.beginPath();
+        context.fillStyle = 'gray';
+        RGraph.Text(context,
+                    'Verdana',
+                    7,
+                    obj.canvas.width / 2,
+                    obj.Get('chart.gutter.top') - 6,
+                    'The subtitle',
+                    'center',
+                    'center');
+    context.fill();
+}
+
+DrawSubTitle(myLine);
+
+ + +
 
 
+

Crosshairs

+ +
+ [No canvas support] + +
+ + + +

+ Some charts type have the ability to use crosshairs. The supported charts are: +

+ + + +

+ There are various options that control the crosshairs, though because some apply to the readout, they are only applicable to + the Scatter chart. The crosshairs can be customised by stipulating the linewidth, the color and whether only the horizontal, + vertical or both lines are shown. +

+ +

Crosshairs and the Scatter chart

+

+ Because the X axis is scaled, the Scatter chart has the extra ability of having a coordinates readout when + the crosshairs are in use. This is shown in the example above. The appropriate properties are: +

+ + + +

+ In the above example the coordinates are put in the text input by using the custom event oncrosshairs. This is as + follows: +

+ + 
+function myFunc (obj)
+{
+    var x = obj.canvas.__crosshairs_x__;
+    var y = obj.canvas.__crosshairs_y__;
+
+    document.getElementById("crosshairs.out").value = x + ',' + y;
+}
+RGraph.AddCustomEventListener(scatter, 'oncrosshairs', myFunc);
+
+ + +
 
 
+

Known issues

+ +

+ There's a few known issues documented here +

+ + +

+ + \ No newline at end of file -- cgit v1.2.1