How to transfer the image on a TUniChart to a TImage or TCanvas

[Woutero]

Sherzod
How do I transfer the image on a TUniChart to a BitMap so that I can save the chart to a MemoryStream to be loaded by an TImage?

Alternatively, how do I transfer the image on a UniChart  to a TCanvas?

In Delphi it would be as below, but UniChart does not have Draw as a member:

ThisChart:TChart; 
BitMap : TBitMap;
MyStream :TMemoryStream;
X,Y : integer;

Bitmap:=TBitmap.Create;
  try
    X := ThisChart.Width;
    Y := ThisChart.Height;
    Bitmap.Height:=Y;
    Bitmap.Width:=X;
    ThisChart.Draw(Bitmap.Canvas, Rect(0, 0, X, Y));
    MyStream:=TMemoryStream.Create;
    Bitmap.SaveToStream(MyStream);
  finally
    Bitmap.Free;
  end;

Image1.Picture.Bitmap.LoadFromStream( MyStream );

 

[Sherzod]

@Woutero

 

[Woutero]

Thank you Sherzod.
Though when I do

 UniSession.AddJS('Form1.Chart1.chart.save({type: ''image/png''})');

then, I get an error: "Form1.Chart1.chart.save is not a function"

My MainForm is named Form1 and my UniChart is named Chart1.
I'm using UniGUI Complete Professional V1.90.0.1560 

[Sherzod]

@Woutero

procedure TMainForm.UniButton1Click(Sender: TObject);
begin
  UniChart1.SaveImage;
end;

procedure TMainForm.UniChart1ChartImage(Sender: TUniCustomChart; Image: TGraphic);
var
  fName : string;
begin
  fName := UniServerModule.LocalCachePath + 'Chart.png';
  Image.SaveToFile(fName);
  UniSession.SendFile(fName);
end;

 

[Woutero]

Thank you Sherzod, it works!

[Woutero]

Hi Sherzod
I have a problem.
The UniChart1.SaveImage will eventually trigger the UniChart1ChartImage event.
However, I need the UniChart1ChartImage event to fire earlier so that I can use the result still within the
UniButton1Click procedure.

Example:  UniButton1Click calls DoSomething

procedure DoSomething;
begin
  UniChart1.SaveImage;
  // I want to use the png file created by UniChart1ChartImage here.
  // but the UniChartImage event only triggers after DoSomething procedure has finished.

  // So I need to call  UniChart1.SaveImage earlier, before I execute DoSomething

end;

So I'm looking for an event that will trigger every time just after a Chart has been drawn/updated?
Which event fires just after a UniChart has been drawn/updated?
Then I can use that event to call UniChart1.SaveImage to create the png file upfront before DoSomething is executed.

[Sherzod]

22 hours ago, Woutero said:

So I'm looking for an event that will trigger every time just after a Chart has been drawn/updated?

If I understand you correctly, you can use these client events I think:

[Woutero]

Thanks Sherzod

So how do I execute

UniChart1.SaveImage;

from within the chart.redraw event?

Remember that when I use

UniSession.AddJS('Form1.Chart1.chart.save({type: ''image/png''})');

then, I get an error: "Form1.Chart1.chart.save is not a function"

[Sherzod]

2 minutes ago, Woutero said:

from within the chart.redraw event?

You can try sending an ajaxRequest to the server inside this event, and execute the server side code.

[Woutero]

Thanks, can you please give a code example? In essence I want to trigger the  

procedure TMainForm.UniChart1ChartImage(Sender: TUniCustomChart; Image: TGraphic);

event on demand

[Sherzod]

Once again, please clarify your case step by step.
Perhaps we will find another optimal solution.

[Woutero]

Thanks for your continued help Sherzod. I really appreciate it.

As I understand, UniChart1.SaveImage; triggers the event: 

UniChart1ChartImage(Sender: TUniCustomChart; Image: TGraphic)

All I want to do is to trigger this event on request. Is that possible?   

Is there any UniSession.AddJS() code that can do this?

[Woutero]

Sherzod
I am able to trigger the UniChart1ChartImage event on demand by using a UniTimer set to RunOnce.
Every time I update a chart, I enable this Timer which then calls  UniChart.SaveImage
which then triggers the ChartImage event.

[Woutero]

On 4/13/2024 at 4:55 PM, Sherzod said:

@Woutero

procedure TMainForm.UniButton1Click(Sender: TObject);
begin
  UniChart1.SaveImage;
end;

procedure TMainForm.UniChart1ChartImage(Sender: TUniCustomChart; Image: TGraphic);
var
  fName : string;
begin
  fName := UniServerModule.LocalCachePath + 'Chart.png';
  Image.SaveToFile(fName);
  UniSession.SendFile(fName);
end;

 

Sherzod

When using Image.SaveToFile(FileName), how does one set the file type?

For example, if I want to use a jpg, how do I set JPG, or does UniGUI automatically look at the extension of the FileName?

[Woutero]

Also, when using Image.SaveToStream() within

procedure TMainForm.UniChart1ChartImage(Sender: TUniCustomChart; Image: TGraphic);

 what is the default image type, or how does one set it?  

[Sherzod]

Hello,

3 hours ago, Woutero said:

default image type

The default image type is png.

I will check...