We would like to draw a line at maximum value on a chart - teechart

Question

We are using FastReport tool for reporting.
On this report there is a teechart where we would like to draw a line at maximum value of some bar charts.
We have tried to solve the problem with adding new series but the problem is that the line doesn't start at x = 0.
How can we achieve that there would be a line at maximum values starting at x = 0 (right after y axis).
Example with series, not starting at x=0
Example of code for drawing the line:
void __fastcall TFTedPoro::cxButton2Click(TObject *Sender)
{
double XMin, XMax, YVal;
frxReport1->LoadFromFile("porocilo.fr3");
TfrxChartView *cv;
cv = (TfrxChartView *)frxReport1->FindObject("Chart1");
if (cv != NULL)
{
cv->Chart->Series[0]->Marks->Visible = false;
cv->Chart->Series[1]->Marks->Visible = false;
cv->Chart->Series[2]->Marks->Visible = false;
cv->Chart->Series[3]->Marks->Visible = false;
cv->Chart->Series[4]->Marks->Visible = false;
cv->Chart->Series[5]->Marks->Visible = false;
cv->Chart->Series[6]->Marks->Visible = false;
if (max_vred >= 350)
{
cv->Chart->LeftAxis->Maximum = max_vred;
}
}
XMin = cv->Chart->Series[0]->XValues->MinValue;
XMax = cv->Chart->Series[0]->XValues->MaxValue;
YVal = cv->Chart->Series[0]->YValues->MaxValue;
for (int i = 1; i < cv->Chart->SeriesCount()-1;i++)
{
XMin = Min(XMin, cv->Chart->Series[i]->XValues->MinValue);
XMax = Max(XMax, cv->Chart->Series[i]->XValues->MaxValue);
YVal = Max(YVal, cv->Chart->Series[i]->YValues->MaxValue);
}
cv->Chart->Series[8]->AddXY(XMin-1, YVal);
cv->Chart->Series[8]->AddXY(XMax+1, YVal);
cv->Chart->Axes->Bottom->SetMinMax(XMin-0.5, XMax+0.5);
frxReport1->ShowReport(true);
}
The result looks like this:
Chart with code on button click

Answer 1

Use a TColorLineTool as in the example in the Features Demo:
The Features Demo is shipped with TeeChart VCL evaluation version:
Update:
If you don't have access to the Chart Tools, another approach would be using a TLineSeries with two values.
Note you can set a first XValue smaller to the smallest XValue in your other series, and a second XValue bigger than the biggest XValue in your other series. Then, you can manually set the bottom axis Minimum and Maximum (ie through SetMinMax(min, max) function) to only fit the points in your original series.
Here it is a simple example:
uses Series, Math;
procedure TForm1.FormCreate(Sender: TObject);
var i: Integer;
XMin, XMax, YVal: double;
begin
for i:=0 to 7 do
begin
with Chart1.AddSeries(TBarSeries) as TBarSeries do
begin
Marks.Visible:=false;
FillSampleValues();
end;
end;
XMin:=Chart1[0].XValues.MinValue;
XMax:=Chart1[0].XValues.MaxValue;
YVal:=Chart1[0].YValues.MaxValue;
for i:=1 to Chart1.SeriesCount-1 do
begin
XMin:=Min(XMin, Chart1[i].XValues.MinValue);
XMax:=Max(XMax, Chart1[i].XValues.MaxValue);
YVal:=Max(YVal, Chart1[i].YValues.MaxValue);
end;
with Chart1.AddSeries(TLineSeries) as TLineSeries do
begin
AddXY(XMin-1, YVal);
AddXY(XMax+1, YVal);
end;
Chart1.Axes.Bottom.SetMinMax(XMin-0.5, XMax+0.5);
end;
This is how the example above looks for me here:
A third alternative would be to manually draw an horizontal line at OnAfterDraw. Ie:
procedure TForm1.Chart1AfterDraw(Sender: TObject);
var Ythreshold: Double;
tmpY: Integer;
begin
Ythreshold:=Chart1[0].YValues.MaxValue;
tmpY:=Chart1.Axes.Left.CalcPosValue(Ythreshold);
Chart1.Canvas.Pen.Color:=clRed;
Chart1.Canvas.Line(Chart1.Axes.Bottom.IStartPos, tmpY, Chart1.Axes.Bottom.IEndPos, tmpY);
end;