Can Line Chart charts base renderer by category

Question

I have done some Googling on this, but frankly I'm not sure
what to even search for. Here is what my boss wants:
A month by month chart of sales showing revenue trends as
well as projections for then next two months. He wants a solid line
for actual data in existing months which turns into a dotted line
with projection data for future months.
I have downloaded and played with the code from quietly
scheming (
http://www.quietlyscheming.com/blog/charts/dashed-lines/)
but it seems to apply to the entire line.
I'm not sure if the direction I should be taking is two
different line renders based on the category axis, or a way to make
the renderer smart enough to change the line at the appropriate
time.
Thoughts please?
Thanks.

Answer 1

I'm still playing with this solution, but for what it's worth
this is what I am doing:
I downloaded the source from quietly scheming for the dashed
line renderer. (
http://www.quietlyscheming.com/blog/charts/dashed-lines/)
I changed the DashedLineSeries to a ProjectionLineSeries and
changed the DashedLineRenderer to be ProjectionLineRenderer. Then
in the renderer, I changed the updateDisplayList method to loop
over the LineSeriesItems (_lineSegment.items array) and find where
past meets future. Note: in doing this, I made an assumption that
your xValue would be a date to use this series. I then used a
combination of the drawPolyLine and drawDashedPolyLine methods from
their respective graphics utility classes to draw the applicable
portions of the line.
Here is the contents of the
ProjectionLineRenderer.updateDisplayList method as I have it now.
override protected function
updateDisplayList(unscaledWidth:Number,
unscaledHeight:Number):void
var stroke:IStroke = getStyle("lineStroke");
var form:String = getStyle("form");
var pattern:Array = getStyle("dashingPattern");
pattern = (pattern == null) ? _pattern : pattern;
graphics.clear();
var current_date:Date = new Date();
var beginning_of_month:Date = new
Date(current_date.getMonth(),1,current_date.getFullYear());
var projected_items:Array = new Array();
// Loop over the lineseriesitems
for(var i:int = 1;i<_lineSegment.items.length;i++)
// Grab the items whose dates are in the future
if(LineSeriesItem(_lineSegment.items
).xValue = beginning_of_month)
// If this is the first item that is in the future, back
// up and grab the previous one so our dotted has a starting
point
if(projected_items.length == 0 && i > 0)
projected_items.push(_lineSegment.items[i-1]);
// Add the future data points into the projected array
projected_items.push(_lineSegment.items);
// Draw the solid portion of the line. Notice the end point
is the size of the entire array, minus the future points.
// Adjusted by two because they overlap one point and the
array starts at 0.
GraphicsUtilities.drawPolyLine(graphics,_lineSegment.items,_lineSegment.start,_lineSegmen t.end,"x","y",stroke,form);
// Draw the dashed portion with the projected_items array
DashedGraphicUtilities.drawDashedPolyLine(graphics, stroke,
pattern, projected_items);
Technically, I am also assuming that the last data point is
the current month, and therefore the projected one. Based on that,
the date math is probably unnecessary, but maybe I'll change that
later.