adaptive use of Distance parameter

[Fenichel]

I am trying to make dynamic use of the new Axis.Title.Distance parameter. My code creates simple Cartesian graphs dynamically, so I know the LeftAxis's Minimum, Maximum, and Increment only at run time. I'd like to use Distance to move the title out just enough to clear the widest label. Simple code working from the precision required for Minimum, Maximum, and Increment doesn't work, because the labels might be '0', '10', ..., '90' when Minimum is -0.002 and Maximum is 95.768. After the Minimum, Maximum, and Increment have been set, is there an easy way to pull out the labels as a tStringList or, even better, are the labels already found inside a program-accessible tRect?

[Fenichel]

I didn't mean to suggest that there was no way to get the width of the Labels column.

Code: Select all

    function  LabelsWidth(Chart: tCustomChart; Axis: tChartAxis): integer;
      (* compute the width (in pixels) of the labels of this vertical axis.
       This code ASSUMES that the longest label (in chars) will be the widest
       (in pixels) *)

      var
        MaxLength: integer;
        ThisLabelValue: real;
        strLabel, strLongest: string;
        SavedFont: tTeeFont;

      begin (* LabelsWidth *)
        SavedFont := tTeeFont.Create();
        try     (* must clean up SavedFont *)
          MaxLength := 0;
          with Axis do
            begin (* Axis *)
              if Minimum > 0 then
                ThisLabelValue := trunc(Minimum / Increment) * Increment
              else if Minimum > -Increment then
                ThisLabelValue := -Increment
              else
                ThisLabelValue := - (trunc(abs(Minimum) / Increment) + 1) * Increment;

              // here with LabelValue one Increment LESS THAN actual first label
              while ThisLabelValue <= Maximum - Increment do
                begin (* test next label *)
                  ThisLabelValue := ThisLabelValue + Increment;
                  strLabel := FloatToStrF(ThisLabelValue, ffGeneral, 15, 0);
                  if length(strLabel) > MaxLength then
                    begin (* found longest to date *)
                      strLongest := strLabel;
                      MaxLength := length(strLabel)
                    end   (* found longest to date *);
                end   (* test next label *);
              SavedFont.Assign(Chart.Canvas.Font);
              Chart.Canvas.Font.Assign(LabelsFont);
              Result := Chart.Canvas.TextWidth(strLongest);

              Chart.Canvas.Font.Assign(SavedFont)
            end   (* Axis *)
        finally (* must clean up SavedFont *)
          SavedFont.Destroy
        end     (* must clean up SavedFont *)
      end   (* LabelsWidth *);

obviously works, but I'd like to be reassured that the same result is not trivially available from the API.

[Fenichel]

Distance seems to work differently on custom axes from the way it works on native axes. My demo code is in the usual place; the pertinent part of the code (starting at line 118 of ScaleTestMain) is

Code: Select all

        DistanceCorrection := StrToIntDef(lbedDistanceCorrection.Text, 0);
        with chartTest do
          begin (* chartTest *)
            with LeftAxis do
              begin (* LeftAxis *)
                SetMinAndMax(LeftAxis, StrToFloat(lbedMinimum.Text), StrToFloat(lbedMaximum.Text));
                PositionPercent            := StrToIntDef(lbedFPositionPercent.Text, -1);
                SetIncrement(LeftAxis);
                Texts.MarginToAxis         := StrToIntDef(lbedFMarginToAxis.Text, 0);
                LeftFLabelsWidth           := LabelsWidth(chartTest, LeftAxis);
                lbLeftFLabelsWidth.Caption := Format('L °F labels width = %d', [LeftFLabelsWidth]);
                Title.Distance             := LeftFLabelsWidth - DistanceCorrection
              end   (* LeftAxis *);

            with LeftCelsiusScale do
              begin (* LeftCelsiusScale *)
                AdjustLimits;
                PositionPercent            := StrToIntDef(lbedCPositionPercent.Text, 0);
                Texts.MarginToAxis         := StrToIntDef(lbedCLabelsMargin.Text, 0);
                LeftCLabelsWidth           := LabelsWidth(chartTest, LeftCelsiusScale);
                lbLeftCLabelsWidth.Caption := Format('L °C labels width = %d', [LeftCLabelsWidth]);
                Title.Distance             := LeftCLabelsWidth - DistanceCorrection
              end   (* LeftCelsiusScale *);

and the pertinent part of the resulting form is

Screenshot 2024-10-07 123342.jpg (124.75 KiB) Viewed 24494 times

Here the °F title is obviously closer to the red labels than the °C title is to the blue labels, even though the widths of the two label columns are the same. What am I missing?

[Fenichel]

In previous post, it was impolite of me to not explicitly say where my demo code is. It is at https://www.fenichel.net/programs/ScaleTest.zip

[Yeray]

Hello,

I've found you've set the LeftAxis.LabelsSize to 12 at design time, which affects the calculations of the margins to be applied.
Setting it to 0 as per default seems to fix the issue for me here.

It was tricky to find it.
If you think you've found a bug, arranging a simple example project we can run as-is here, with the minimum code to reproduce that specific issue, helps a lot and minimizes the time to the resolution.
Thanks in advance.

[Fenichel]

I thought that the <Axis>.Labels.Font.Size slider in the Chart Editor

chart editor.jpg (54.52 KiB) Viewed 22885 times

was connected to the <Axis>.LabelSize entry in the Object Inspector

object inspector.jpg (123.04 KiB) Viewed 22885 times

Now I'm curious: What is the Object Inspector entry for?

[Yeray]

Hello,

These are two different properties: TChartAxis.LabelsFont.Size and TChartAxis.LabelsSize.
Both can be found in the object inspector:

LabelsFontSize_LabelsSize_inspector.png (23.22 KiB) Viewed 22567 times

And also in the editor:

LabelsSize_editor.png (27.14 KiB) Viewed 22567 times

LabelsFontSize_editor.png (26.68 KiB) Viewed 22567 times