Learn AFL code : How to show shape in afl

Well we have have plotted our price and desired EMA in the chart. Now may be we want to put an arrow in the chart. This will help us to recognize our signal better. How can I do this? Here is the code for it.

_SECTION_BEGIN("visual arrow ema cross over");
SetChartOptions(0,chartShowArrows|chartShowDates);
Plot( Close, "Close", ParamColor("Color", colorBlack ), styleNoTitle | ParamStyle("Style") | GetPriceStyle() ); 

Buy= Cross(EMA( C, 20 ), EMA( C, 50 ));
Sell= Cross(EMA( C, 50 ), EMA( C, 20 ));

PlotShapes(IIf(Sell==1, shapeDownArrow, shapeNone), colorRed, 0,High, Offset=-20);
PlotShapes(IIf(Buy==1, shapeUpArrow , shapeNone), colorGreen, 0,Low, Offset=-20);

Plot( EMA( C,20), "20 EMA Close",ParamColor("EMA 20 Color", colorGreen ),styleNoRescale);
Plot( EMA( C,50), "50 EMA Close",ParamColor("EMA 50 Color", colorRed ),styleNoRescale); 
_SECTION_END();

here Plot function is making this arrow.

SYNTAX :

PlotShapes( shape, color, layer = 0, yposition = graph0, offset = -12, XShift = 0 );

PlotShapes(IIf(Sell==1, shapeDownArrow, shapeNone), colorRed, 0,High, Offset=-20);
PlotShapes(IIf(Buy==1, shapeUpArrow , shapeNone), colorGreen, 0,Low, Offset=-20);

Here I used Arrow shape, but if you want you have wide range of shape options available. here is the list
Constants for shapes:

shapeNone, shapeUpArrow, shapeDownArrow, shapeHollowUpArrow, shapeHollowDownArrow, shapeSmallUpTriangle, shapeSmallDownTriangle, shapeHollowSmallUpTriangle, shapeHollowSmallDownTriangle, shapeUpTriangle, shapeDownTriangle, shapeHollowUpTriangle, shapeHollowDownTriangle, shapeSmallSquare, shapeHollowSmallSquare, shapeSquare, shapeHollowSquare, shapeSmallCircle, shapeHollowSmallCircle, shapeCircle, shapeHollowCircle, shapeStar, shapeHollowStar, shapeDigit0, shapeDigit1, shapeDigit2, shapeDigit3, shapeDigit4, shapeDigit5, shapeDigit6, shapeDigit7, shapeDigit8, shapeDigit9, shapePositionAbove

So instead of using (Upper arrow)

PlotShapes(IIf(Sell==1, shapeDownArrow, shapeNone), colorRed, 0,High, Offset=-20);
We can use this also (Upper triangle)
PlotShapes(IIf(Buy==1, shapeUpTriangle , shapeNone), colorGreen, 0,Low, Offset=-20);

Debarghya Mukherjee
Mobile: (+91)-9038787021
Email: debarghya_mkr@yahoo.com