Hello. In my current project I have to create xlsx charts programmaticaly.
As I can see, at the moment POI has not enought capabilities for that. So I
want to collaborate with POI developers to teach POI to work with charts. I
have proposed code to allow user create new charts (
http://apache-poi.1045710.n5.nabble.com/DO-NOT-REPLY-Bug-51196-New-PATCH-Patch-to-simplify-XSSFChart-creation-tp4392907p4392907.html
patch 51196 ), but they still have to fill chart content by themselves.
The next step is to allow users to create different charts without direct
xmlbeans library usage. ECMA-376 describes 16 chart types. So we need to
organize classes in some rational model. I thought a lot about it and here
is my proposal: lets add to XSSFChart factory method, say,
plot(XSSFChartData), to plot a specific data on a chart. XSSFChartData will
be an interface (or an abstract class) that incapsulates specific plot logic
(i.e. working with CTPlotArea).
The implementation could be something like that:
/* XSSFChartData.java */
public interface XSSFChartData() {
void fillChart(CTPlotArea ctArea);
}
/* XSSFChart.java */
public void plot(XSSFChartData data) {
data.fillChart(getCTChart().getPlotArea());
}
/* XSSFScetterChartData.java */
public class XSSFScetterChartData implements XSSFChartData {
public void fillChart(CTPlotArea area) {
CTScetterChart scetterChart = area.addNewScetterChart();
/* .... */
}
}
Here is a code snippet illustrating the idea:
XSSFChart chart = drawing.createChart(anchor);
XSSFScetterChartData chartData = new XSSFScetterChartData();
XSSFScetterChartData.Serie serie = chartData.addSerie();
serie.setXValues(range);
serie.setYValues(anotherRange);
chart.plot(chartData);
I think proposed class names not the best ones, if you know better ones -
welcome.
Here is benefits of such approach:
no any if\switches: polymorphism rules;
the same data can be plotted in multiple charts - orthogonality is always a
plus (if you don't believe me - read "Programmatic Programmer");
I think a new package should be introduced to contain chart data classes
(suppose, org.apache.poi.xssf.usermodel.charts).
What do you think about all this?
Thank you in advance
Roman Kashitsyn
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