Draw.Region: Mistake or just redundant?

[koganam]

I was having some issues with Draw.Region, so decided to write a new class based off of copying its code.

I notice this section in the code, that leaves me a bit confused.

				// cap it end->start
				points[pointIdx].X = chartControl.GetXByBarIndex(chartBars, endIdx + Displacement);
				points[[COLOR="red"]pointIdx++[/COLOR]].Y = chartScale.GetYByValue(Math.Max(chartScale.MinValue, Math.Min(chartScale.MaxValue, Price)));

				points[[COLOR="red"]pointIdx[/COLOR]].X = chartControl.GetXByBarIndex(chartBars, startIdx + Displacement);
				points[pointIdx++].Y = chartScale.GetYByValue(Math.Max(chartScale.MinValue, Math.Min(chartScale.MaxValue, Price)));

(emphasis mine)

Notice that the third line of code merely replaces the self-same points[pointIdx] calculated off of endIdx, with one calculated off of startIdx; and the fourth line of code is an exact duplicate of the second line of code. It seems strange to be immediately replacing code that has not been used, then writing the exact same code for another quantity that has not been used either.

Did you intend to write,

				// cap it end->start
				points[pointIdx].X = chartControl.GetXByBarIndex(chartBars, endIdx + Displacement);
				points[[COLOR="Red"]pointIdx[/COLOR]].Y = chartScale.GetYByValue(Math.Max(chartScale.MinValue, Math.Min(chartScale.MaxValue, Price)));

				points[[COLOR="red"]pointIdx++[/COLOR]].X = chartControl.GetXByBarIndex(chartBars, startIdx + Displacement);
				points[pointIdx++].Y = chartScale.GetYByValue(Math.Max(chartScale.MinValue, Math.Min(chartScale.MaxValue, Price)));

or am I off my rocker?

[NinjaTrader_DaveI]

I believe the key may be with the timing of the increments to pointIdx. Here is the progression that I see in the existing code. We'll assume that pointIdx begins with a value of 1:

1) Change X on index 1
2) Change Y on index 1, then increment pointIdx to 2
3) Change X on index 2
4) Change Y on index 2, then increment pointIdx to 3
5) Rinse/Repeat

In your suggestion, I believe the flow would work as follows:

1) Change X on index 1
2) Change Y on index 1
3) Change X again on index 1, then increment pointIdx to 2
4) Change Y on index 2, then increment pointIdx to 3

Does that provide a bit more clarity, or point you in the right direction?

[koganam]

I believe the key may be with the timing of the increments to pointIdx. Here is the progression that I see in the existing code. We'll assume that pointIdx begins with a value of 1:

1) Change X on index 1
2) Change Y on index 1, then increment pointIdx to 2
3) Change X on index 2
4) Change Y on index 2, then increment pointIdx to 3
5) Rinse/Repeat

In your suggestion, I believe the flow would work as follows:

1) Change X on index 1
2) Change Y on index 1
3) Change X again on index 1, then increment pointIdx to 2
4) Change Y on index 2, then increment pointIdx to 3

Does that provide a bit more clarity, or point you in the right direction?

Thanks. I was off my rocker. I have been looking at code too long!

I looked at that incrementer multiple times, and still did not make the connection that it was assigning, then incrementing: a construct that I have myself used multiple times. I shall turn off the code window for a few days, until I start seeing clearly again.

Thanks for your time.