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Charts - Format Specifiers

Cain

<p>Hello,</p>
<p> </p>
<p>I'm trying to use a custom FormatSpecifier on the x-axis of a chart, but it seems when the report is rendered, my custom format specifier has been replaced with FormatSpecifierImpl.</p>
<p> </p>
<p>When creating the report I do this:</p>
<pre class="_prettyXprint">
Axis xAxisPrimary = chart.getPrimaryBaseAxes()[0];
xAxisPrimary.setFormatSpecifier(new MyFormatSpecifier());</pre>
<p>Now in the event handler for the chart I do something like this:</p>
<p> </p>
<div>
<pre class="_prettyXprint">
@Override
public void beforeDrawAxisLabel(Axis axis, Label label, IChartScriptContext icsc)
{
FormatSpecifier fmt = axis.getFormatSpecifier();

if (fmt instanceof MyFormatSpecifier){
MyFormatSpecifier axisFmt = (MyFormatSpecifier)fmt;
label.getCaption().setValue(axisFmt.format(label.getCaption().getValue()));
}
}</pre>
</div>
<div>The problem is, fmt never comes back as an instance of MyFormatSpecifier. Instead it's always just FormatSpecifierImpl. If I remove the code that sets MyFormatSpecifier, it always returns null as the format specifier, which it should. Maybe there is another way I should be doing it? Are there custom properties I can set in an axis that I can look up so I know how to format the values before they're drawn? If I can do that instead, then once I get to the chart handler I'll know how to format the data for the axis and I can not user a format specifier.</div>
<div> </div>
<div>Thanks.</div>
<div> </div>

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Comments

mwilliams

<p>Could you attach your custom FormatSpecifier classes? I've never tried overriding the default with that.</p>
<p> </p>
<p>Can you also explain in more detail about the end goal of what you're wanting to accomplish?</p>

Cain

<p>Basically what I'm trying to do, is format the data in an axis when the chart is rendered. For example, the x-axis of a line chart represents 15 minute period over the course of a day. So period 0 = 00:00, period 1 = 00:15, period 2 = 00:30 and so on. The result set from the database returns integers 0-95. I need to convert those numbers to the appropriate HH:mm format. It gets more complicated though, as the output format is user configurable, so the numbers could be displayed as 'HH:mm' or 'h:mm a'. The code that creates the chart has access so the user's settings so I need a way to pass that on so when it's rendered, I can do the appropriate conversion. </p>
<p> </p>
<p>We do this when generating a report by assigning an event handler to a data cell that contains the information required to do the conversion. From what I can tell with charts, only the chart itself has an event handler, so I was trying to hook into the beforeDrawAxisLabel method on the chart handler. Unfortunately I cannot create an instance of the chart event handler I wish to use and put the information there, because setEventHandler method only takes a class name. If I could some how get a hold of the ReportDesignHandle from the beforeDrawAxisLabel then I'd have all the information I need as we store the user's formatting as user properties in it.</p>

mwilliams

<p>Try this to get the design handle from the chart script:</p>
<p> </p>
<p></p><pre class="_prettyXprint _linenums:0">icsc.getExternalContext().getScriptable().getDesignHandle()
</pre>

Cain

<p>Which version of BIRT is that for? We're using 4.3.1 and I don't have a method getDesignHandle() for the Scriptable class. I was able to get it through the IExternalContext by casting the return of .getObject() to ReportContextImpl then calling .getDesignHandle() on it. Thanks for pointing me in the right direction.</p>

mwilliams

<p>It worked for me in 4.4. I was able to grab information from the design handle with the method I posted above. It should work in all versions. It just doesn't show "getDesignHandle()" in the suggestions.</p>