Cross hair not drawn when labels are on Chart

[ChartIt]

Hello,

It seems like I have an issue with TChart 2010.

I use the following code to draw a cross hair on a Chart that follows the mouse when moved on the Chart.
The cross hair is following the mouse perfectly if I don't place the two labels "lblHorizontalAxis" and "lblVerticalAxis" directly on the Chart (but place them on the form behind the Chart). The labels are showing some values that are extracted from the Chart while the mouse is moving.

The problem occurs if I place the labels on the Chart itself (where they actually belong).
The labels are getting updated, and following the mouse as they should, but the cross hair is only drawn ones when pressing the mouse, but not following the mouse (which means it doesn't get deleted and redrawn in the OnMouseMove event).

I'm pretty sure I didn't have this problem with TChart 7.
Do you know what has happened, or do you need more explanation/code?
Thanks in advance!

procedure TfrDataLogger.DrawCross(AX, AY: Integer);
begin
with Chart1, Canvas do
begin
Pen.Color := clWhite;
Pen.Style := psSolid;
Pen.Mode := pmXor;
Pen.Width := 1;
//Vertical line:
MoveTo(ax, ChartRect.Top);
LineTo(ax, ChartRect.Bottom);
//Horizontal line:
MoveTo(ChartRect.Left, ay);
LineTo(ChartRect.Right, ay);
end;
end;

procedure TfrDataLogger.Chart1MouseDown(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
if ((FAnalyzeMode = Rule) or (FAnalyzeMode = Tracker) or (FAnalyzeMode = Vernier)) and (Button = MBLeft) then
begin
Chart1[0].GetCursorValues(FStartVernierX, FStartVernierY);
lblHorizontalAxis.Visible := True;
lblVerticalAxis.Visible := True;

if PtInRect(Chart1.ChartRect, Point(X-Chart1.Width3D,Y+Chart1.Height3D)) then //Check if mouse is inside Chart rectangle.
begin
FDrawCrossActive := True;
DrawCross(x, y); //Draw crosshair at current position.
//Store current position:
FOldX := x;
FOldY := y;
//In case of Vernier the first drawn crossHair must remain:
if (FAnalyzeMode = Vernier) then
FOldX := -1;
end;
end;
end;

procedure TfrDataLogger.Chart1MouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);
var
tmpX, tmpY: Double;
begin
Chart1[0].GetCursorValues(tmpX, tmpY);

if FAnalyzeMode = Rule then
begin
lblHorizontalAxis.Caption := FloatToStr(RoundTo(tmpX,-2));
lblHorizontalAxis.Top := Chart1.Axes.Bottom.PosLabels;
lblHorizontalAxis.Left := Chart1.GetCursorPos.X - round(lblHorizontalAxis.Width/2);

lblVerticalAxis.Caption := FloatToStr(RoundTo(tmpY,-2));
lblVerticalAxis.Top := Chart1.GetCursorPos.Y - round(lblVerticalAxis.Height/2);
lblVerticalAxis.Left := Chart1[0].GetVertAxis.PosLabels - lblVerticalAxis.Width;
end;

if (FAnalyzeMode = Tracker) and (Chart1[0].Count <> 0) then
begin
lblHorizontalAxis.Caption := FloatToStr(RoundTo(tmpX,-2));
lblHorizontalAxis.Top := Chart1.Axes.Bottom.PosLabels;
lblHorizontalAxis.Left := Chart1.GetCursorPos.X - round(lblHorizontalAxis.Width/2);

lblVerticalAxis.Caption := FloatToStr(Chart1[0].YValue[Round(tmpX)]);
//lblVerticalAxis.Caption := FloatToStr(RoundTo(tmpY,-2));
lblVerticalAxis.Top := Chart1.GetCursorPos.Y - round(lblVerticalAxis.Height/2);
lblVerticalAxis.Left := Chart1[0].GetVertAxis.PosLabels - lblVerticalAxis.Width;
end;

if FAnalyzeMode = Vernier then
begin
lblHorizontalAxis.Caption := FloatToStr(RoundTo(tmpX - FStartVernierX, -2));
lblHorizontalAxis.Top := Chart1.Axes.Bottom.PosLabels;
lblHorizontalAxis.Left := Chart1.GetCursorPos.X - round(lblHorizontalAxis.Width/2);

lblVerticalAxis.Caption := FloatToStr(RoundTo(tmpY - FStartVernierY, -2));
lblVerticalAxis.Top := Chart1.GetCursorPos.Y - round(lblVerticalAxis.Height/2);
lblVerticalAxis.Left := Chart1[0].GetVertAxis.PosLabels - lblVerticalAxis.Width;
end;

//Delete old crossHair:
if ((FAnalyzeMode = Rule) or (FAnalyzeMode = Tracker) or (FAnalyzeMode = Vernier)) and (FDrawCrossActive) then
begin
if (FOldX <> -1) then
begin
DrawCross(FOldX, FOldY); //Delete old crossHair.
FOldX := -1;
end;

//Check if mouse is inside Chart rectangle:
if PtInRect(Chart1.ChartRect, Point(X-Chart1.Width3D,Y+Chart1.Height3D)) then
begin
DrawCross(x, y); //Draw crosshair at current position.
//Store current position:
FOldX := x;
FOldY := y;
end;
end;
end;

[Yeray]

Hi ChartIt,

There are some variables in your code snipped undefined so we can't run it as-is. Please, try to arrange a simple example project we can run as-is to reproduce the problem here.
However, if I understood well, you are trying to achieve something similar to the Cursor Tool. Take a look at the examples under "All features\Welcome !\Tools\Cursor\".
Here you have a simple example:

Code: Select all

uses Series, TeeTools;

procedure TForm1.FormCreate(Sender: TObject);
begin
  Chart1.View3D:=false;
  Chart1.Legend.Visible:=false;

  with Chart1.AddSeries(TPointSeries) do FillSampleValues;

  with Chart1.Tools.Add(TCursorTool) as TCursorTool do
    FollowMouse:=true;
end;

[ChartIt]

Hi,

I didn't know that function, thanks for that!

Anyway, the problem seems to be here too.
Put a label to a new Chart, and add this code:

procedure TForm1.Chart1MouseMove(Sender: TObject; Shift: TShiftState; X,
Y: Integer);
var
tmpX, tmpY: Double;
begin
Chart1[0].GetCursorValues(tmpX, tmpY);
Label1.Caption := FloatToStr(Round(tmpX));
end;

procedure TForm1.FormCreate(Sender: TObject);
var
i: Integer;
begin
Chart1.View3D := False;
Chart1.Legend.Visible := False;

Chart1.AddSeries(TFastLineSeries);
for i := 0 to 200 do
Chart1.Series[0].AddXY(i, i, '', clRed);

with Chart1.Tools.Add(TCursorTool) as TCursorTool do
FollowMouse := True;
end;

Without updating the label in OnMouseMove everything works fine.
When updating the label (like in the code above) the cursor tool doesn't get drawn.

What do you say?

[Yeray]

Hi ChartIt,

The attached project seems to run fine for me here. Could you please tell us what we have to do to reproduce the problem with it?

MouseMoveUpdate.zip

(1.74 KiB) Downloaded 891 times

Are you using the latest TeeChart version available (v2010.01)?

[ChartIt]

I use the latest version. Downloaded yesterday

If you delete the line:
Chart1.Title.Text.Text:=FloatToStr(Round(tmpX));

you should also see the problem.

[ChartIt]

By adding the line
Chart1.Repaint;
or
Chart1.Refresh;

at the end of the MouseMove event the cross hair gets redrawn, but then it draws on top of the label.

This is not the case when using the line
Chart1.Title.Text.Text := FloatToStr(Round(tmpX));

[Yeray]

Hi ChartIt,

Excuse me, I'm not sure how I was looking at this.
Yes, it seems that, for some reason, when updating a label (with the chart as parent) in the OnMouseMove event (also happens with the tool's OnChange event), the Cursor Tool stops following the mouse. I've added it to the wish list to be investigated for further releases (TV52015292).
As you say, the Chart1.Repaint and the Chart1.Refresh methods work around this. Also you could consider using Annotation tools, Rectangle tools or custom drawing the text on top of the chart instead of using labels.

[ChartIt]

Hi Yeray,

OK, but please note that Repaint and Refresh don't solve the problem completely, see my previous post.

Do you happen to be able to help me out with my newest post in this forum regarding retrieving YValues?

[Yeray]

Hi ChartIt,

And what about this?

Code: Select all

Chart1.Tools[0].Repaint;

Do you happen to be able to help me out with my newest post in this forum regarding retrieving YValues?

Of course, as soon as possible.

[ChartIt]

That seems to work, thanks!