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getting series label in method beforedrawdatapoint

mrbrown

Hi, 
I'm working on a bar chart and I would like to change each bar color depending on the X series label. 
I know that I can use the method beforedrawdatapoint : 
<pre class='_prettyXprint _lang-auto _linenums:0'>
/**
* Called before drawing each datapoint graphical representation or marker.
*
* @param dph
* DataPointHints
* @param fill
* Fill
* @param icsc
* IChartScriptContext
*/

function beforeDrawDataPoint(dph, fill, icsc){}
</pre>
And I also know to change the bar color depending on the Y value (that I get from the method dph.getOrthogonalValue() : 
<pre class='_prettyXprint _lang-auto _linenums:0'>
function beforeDrawDataPoint(dph, fill, icsc)
{
chart = icsc.getChartInstance();
warn = 70;
crit = 90;

if (dph.getOrthogonalValue() >= warn_marker && dph.getOrthogonalValue() <= crit_marker) {
fill.set(255,155,30);
} else if (dph.getOrthogonalValue() >= crit_marker) {
fill.set(255,55,55);
} else {
fill.set(0,180,0);
}
}
</pre>
But how can I get the X series label and compare it with String to apply a specific color ("Up"=> green bar, "Down" => red bar)? 
Thanks for your help.

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Comments

mrbrown

any idea?
please ask me if you didn't understand something in my last post, I'm not sure that my english is very good ^^

cypherdj

I'm guessing using dph.getBaseValue() would get you the X series value, but I could be mistaken.

Hope that helps,
Cedric

mwilliams

Nope, I don't think you're mistaken Cedric. I believe that is correct.

mrbrown

Thanks guys, it's working well.
But I've one more problem, when I set the color this way :

function beforeDrawDataPoint(dph, fill, icsc)
{
if (dph.getBaseValue() == "Up")
fill.set(0,180,0);
}

I loose the transparency That I've set on bars (I've attached an example with this post)

Do you know the method that I could use to apply it again?

Thanks!

cypherdj

The Fill interface which is passed into the beforeDrawDataPoint method as parameter is extended by the ColorDefinition class. 
 
This ColorDefinition class in turn has a setTransparency(int) method. 
 
You can check those in the field guide to reporting, in the BIRT Charting Programmer reference, under API reference->Charting Engine API reference. 
<a class='bbc_url' href='http://www.birt-exchange.com/documentation/BIRT_220/wwhelp/wwhimpl/js/html/wwhelp.htm'>http://www.birt-exchange.com/documentation/BIRT_220/wwhelp/wwhimpl/js/html/wwhelp.htm</a> 
 
So I guess you could check that the Fill object passed in is an instance of ColorDefinition, and apply your transparency that way. 
 
<pre class='_prettyXprint _lang-auto _linenums:0'>
function beforeDrawDataPoint(dph, fill, icsc)
{
if (dph.getBaseValue() == "Up")
fill.set(0,180,0);
if (fill instanceof ColorDefinition){
ColorDefinition colorDef = (ColorDefinition) fill;
colorDef.setTransparency(127); // translucent?
}
}
</pre>
 
I think that should do it. You might want to check the value passed into setTransparency, but that should roughly do the job. Also, if that doesn't work, I guess that probably means your Fill object is not a ColorDefinition, in which case I'm not sure what you could do. 
 
Note, I haven't tested any of this code, just guessing from the API reference. 
 
Hope that helps, 
Cedric

mrbrown

Thanks cedric, I"ll test it as soon as I can.

mrbrown

Hi, 
I'm sorry to reply so late, but I have a lot to do with birt, I'm enjoying developping with this framework

it seems that your solution is not working. Apparently, this syntax is not recognized : 
<pre class='_prettyXprint _lang-auto _linenums:0'>
ColorDefinition colorDef = (ColorDefinition) fill;
</pre>
Maybe it's the ColorDefinition object that is not recognized, do I have to import specific packages? 
This is the error line generated : 
<pre class='_prettyXprint _lang-auto _linenums:0'>
missing ';' before instruction at line 17 of chart script:' ColorDefinition colorDef = (ColorDefinition) fill;'
</pre>
Do you have an idea? 
This is my entire script : 
<pre class='_prettyXprint _lang-auto _linenums:0'>
/**
* Called before drawing each datapoint graphical representation or marker.
*
* @param dph
* DataPointHints
* @param fill
* Fill
* @param icsc
* IChartScriptContext
*/

function beforeDrawDataPoint(dph, fill, icsc)
{
if (dph.getBaseValue() == "Up")
fill.set(0,180,0);
if (fill instanceof ColorDefinition) {
ColorDefinition colorDef = (ColorDefinition) fill;
colorDef.setTransparency(127);
}
}
</pre>
I've attached the full exception trace with this post. 
Thanks for your help.

cypherdj

Hi MrBrown, 
 
I don't think it's an issue with a missing package, otherwise you would get a syntax error at the previous line in the script. 
 
What might be the issue is that the variable type is not needed, so the script should probably be: 
<pre class='_prettyXprint _lang-auto _linenums:0'>
function beforeDrawDataPoint(dph, fill, icsc)
{
if (dph.getBaseValue() == "Up")
fill.set(0,180,0);
if (fill instanceof ColorDefinition) {
colorDef = (ColorDefinition) fill;
colorDef.setTransparency(127);
}
}
</pre>
 
Again, I haven't tried this code, so I cannot guarantee this will work ;-) 
 
Regards, 
Cedric

mrbrown

It doesn't work either. But I found the solution, it was simple ^^ : 
<pre class='_prettyXprint _lang-auto _linenums:0'>
function beforeDrawDataPoint(dph, fill, icsc)
{
if (dph.getBaseValue() == "Up") {
fill.set(0,180,0);
fill.setTransparency(127);
}

}
</pre>
Thanks guys!!!