How to create and return PNG image using HTTP-server?

[artem101]

Is there an example how to draw and return PNG image using fpWeb module?
Thanks.

[lucamar]

There might be but I don't know of any. However, it shouldn't be too difficult: use a TPicture or directly a TPortableNetworkGraphic to draw whatever you need, save it to a file/stream and make the server return that file/stream.

You could even transfer directly the TPicture/TPortableNetworkGraphic  to the Response.ContentStream using SaveToStream, avoiding all iteraction with the disk (other than OS swapping, o.c.)

Edit: Replaced TPNGImage by TPortableNetworkGraphic 

[artem101]

I make this code, but it doesn`t work:

Code: Pascal  [Select][+][-]

1. procedure TFPWebModule1.DataModuleRequest(Sender: TObject; ARequest: TRequest;
2.   AResponse: TResponse; var Handled: Boolean);
3. const
4.   WIDTH = 256;
5.   HEIGHT = 256;
6. var
7.   str: String;
8.   img: TPortableNetworkGraphic;
9.   textWidth, textHeight: integer;
10.   memStrm: TMemoryStream;
11. begin
12.   //WriteLn('Url: ', ARequest.URI);
13.   //WriteLn('Args: ', ARequest.QueryFields.Text);
14.  
15.   with ARequest.QueryFields do
16.     str := Format('x=%s y=%s z=%s', [Values['x'], Values['y'], Values['z']]);
17.  
18.  
19.   img := TPortableNetworkGraphic.Create;
20.   memStrm := TMemoryStream.Create;
21.   try
22.     // Create image
23.     img.SetSize(WIDTH, HEIGHT);
24.  
25.     img.Canvas.Font.Color:=clRed;
26.     img.Canvas.GetTextSize(str, textWidth, textHeight);
27.     img.Canvas.TextOut((WIDTH - textWidth) div 2, (HEIGHT - textHeight) div 2, str);
28.  
29.     // Send image to output stream
30.     img.SaveToStream(memStrm);
31.     AResponse.ContentStream.CopyFrom(memStrm, memStrm.Size);
32.     AResponse.ContentStream.Position:=0;
33.     AResponse.WriteContent;
34.   finally
35.     img.Free;
36.     AResponse.ContentStream:=nil;
37.     memStrm.Free;
38.   end;
39.  
40.   AResponse.Code:=200;
41.   AResponse.ContentType:='image/png';
42.   Handled:=true;
43. end;  

First problem:

unit1.pas(64,15) Error: identifier idents no member "WriteContent"

After I commented line

Code: Pascal  [Select][+][-]

1. AResponse.WriteContent;

server started to work, but second problem appeared
https://ibb.co/6gbHSn5
at line

Code: Pascal  [Select][+][-]

1. img.SetSize(WIDTH, HEIGHT);