Legend set height

[Kai]

We are using the TeeChartStandard2014 package.

I use the follwing to create a large TBarSeries series Series1.FillSampleValues(100);

The result looks like this:

test.jpg (362.05 KiB) Viewed 7050 times

Is it possible the set a fixed height for the legend and use a custom scrollbar?

If i add a scrollbar i can navigate with Chart1.Legend.FirstValue := ScrollBarLegend.Position;

I hope I could describe the problem well.

Thanx.

[Yeray]

Hello Kai,

TeeChart Pro includes the TLegendScrollBar between the Chart Tools.
Here you have an example of it:

Code: Select all

uses Series, TeeLegendScrollBar;

procedure TForm1.FormCreate(Sender: TObject);
var i: Integer;
begin
  with Chart1.AddSeries(TBarSeries) do
    for i:=0 to 99 do
      Add(i);

  Chart1.Legend.Alignment:=laTop;

  Chart1.Tools.Add(TLegendScrollBar);
  Chart1.Legend.MaxNumRows:=4;
end;

Note this tool is designed for the default vertical Legend Alignment (aka laLeft/laRight). In an horizontal Alignment (aka alTop/alBottom), when you increment the position of the scrollbar a unit, the top-left element of the legend disappears, all the other elements move a step left (the elements on the left move a row above and to the right edge), and a new element appears on the right-bottom.
This may be better explained with two images.
Here it is how it looks when you start the application running the code above:

2014-04-30_1111.png (64.04 KiB) Viewed 7041 times

And this is how it looks if you press the right arrow on the legend scrollbar once:

2014-04-30_1112.png (64.01 KiB) Viewed 7042 times

The alternative would be draw your shapes and texts manually at OnAfterDraw event.

[Kai]

Hello Yeray,

thank you for your answer.

If i use something like that:

Code: Select all

var
  intI: Integer;
begin
  ChartAccounting.Legend.Alignment := laTop;

  for intI := 0 to 100 do
   begin
    with frmChart.ChartAccounting.AddSeries(TBarSeries) as TBarSeries do
     begin
      FillSampleValues(1);
    end;
  end;

  frmChart.ChartAccounting.Draw();
end;

It looks like that:

test.jpg (231.22 KiB) Viewed 7024 times

So the problem is that there are missing series in the legend.

How can i solve this? Thanx.

[Yeray]

Hi Kai,

So the problem is that there are missing series in the legend.

How can i solve this?

If you don't specify the Legend's MaxNumRows, the maximum number of rows will be 10. In the case above, to fit 101 items you'll need 21 rows:

Code: Select all

ChartAccounting.Legend.MaxNumRows:=21;

[Kai]

Works

Thank you.

Do you have a short sample, how i can calculate the needed value of MaxNumRows?

[Yeray]

Hi Kai,

Do you have a short sample, how i can calculate the needed value of MaxNumRows?

We take care of a few aspects of the chart to calculate this.
This is our ItemHeight function:

Code: Select all

Function TCustomChartLegend.CalcItemHeight:Integer;
begin
  result:=ParentChart.Canvas.FontHeight;

  if Symbol.Visible then
     if Symbol.HeightUnits=lcsPercent then
     begin
       if Symbol.Height>100 then
          result:=Round(result*Symbol.Height*0.01);
     end
     else
       result:=Max(result,Symbol.Height);

  if HasCheckBoxes then
     result:=Math.Max(6+TeeCheckBoxSize,result);

  Inc(result,FVertSpacing);

  if Vertical and DividingLines.Visible then
     result:=result+{$IFDEF FMX}Round{$ENDIF}(DividingLines.Width);
end;

And you also need to know the YLegend. We use this FirstItemTop function for that:

Code: Select all

Function TCustomChartLegend.FirstItemTop:Integer;
begin
  result:={$IFDEF FMX}Round{$ENDIF}(ShapeBounds.Top);

  if Frame.Visible then
     Inc(result,({$IFDEF FMX}Round{$ENDIF}(Frame.Width) div 2));

  if IDrawTitle then
     Inc(result,{$IFDEF FMX}Round{$ENDIF}(Title.Height)+2);
end;

Then, after having calculated this, we will be able to call our MaxLegendRows function:

Code: Select all

  Function MaxLegendRows(YLegend,ItemHeight:Integer):Integer;
  begin
    With ParentChart do
    Begin
      if (YLegend<ChartRect.Bottom) and (ItemHeight>0) then
      Begin
        result:={$IFDEF FMX}Round{$ENDIF}(ChartHeight-FrameWidth-YLegend+ChartRect.Top) div ItemHeight;
        result:=Math.Min(result,TotalLegendItems);
      end
      else result:=0;
    end;
  end;

This is how we call these functions in the Legend CalcRect function:

Code: Select all

  ItemHeight:=CalcItemHeight;
//...
    NumRows:=MaxLegendRows(FirstItemTop,ItemHeight);

    if MaxNumRows <> 0 then
       NumRows:=Math.Min(NumRows,MaxNumRows);

The above is an extract of Chart.pas, part of TeeChart sources. Being just a snipped of code means this won't probably compile in an application different than TeeChart sources but can give you an idea of what calculations you should make to emulate a similar effect.

[Kai]

Thank you very much. I will try it.