(Delphi ActiveX) PayPal Generate QR Code

Generates a QR code for an invoice, by ID.

The QR code is a PNG image in Base64-encoded format that corresponds to the invoice ID.

Note: A QR code can only be generated for an invoice that has been both created and sent.

See also Generate QR Code

Chilkat for Delphi Downloads Chilkat ActiveX DLL for Delphi Chilkat non-ActiveX DLL for Delphi * The examples here use the ActiveX DLL.

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Chilkat_TLB;

...

procedure TForm1.Button1Click(Sender: TObject);
var
jsonToken: TChilkatJsonObject;
sbAuth: TChilkatStringBuilder;
rest: TChilkatRest;
bAutoReconnect: Integer;
success: Integer;
sbPath: TChilkatStringBuilder;
numReplacements: Integer;
sbJsonResponse: TChilkatStringBuilder;
json: TChilkatJsonObject;
pngData: TChilkatBinData;

begin
// Note: Requires Chilkat v9.5.0.64 or greater.

// This requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

// Load our previously obtained access token. (see PayPal OAuth2 Access Token)
jsonToken := TChilkatJsonObject.Create(Self);
jsonToken.LoadFile('qa_data/tokens/paypal.json');

// Build the Authorization request header field value.
sbAuth := TChilkatStringBuilder.Create(Self);
// token_type should be "Bearer"
sbAuth.Append(jsonToken.StringOf('token_type'));
sbAuth.Append(' ');
sbAuth.Append(jsonToken.StringOf('access_token'));

// Make the initial connection.
// A single REST object, once connected, can be used for many PayPal REST API calls.
// The auto-reconnect indicates that if the already-established HTTPS connection is closed,
// then it will be automatically re-established as needed.
rest := TChilkatRest.Create(Self);
bAutoReconnect := 1;
success := rest.Connect('api.sandbox.paypal.com',443,1,bAutoReconnect);
if (success <> 1) then
  begin
    Memo1.Lines.Add(rest.LastErrorText);
    Exit;
  end;

// ----------------------------------------------------------------------------------------------
// The code above this comment could be placed inside a function/subroutine within the application
// because the connection does not need to be made for every request.  Once the connection is made
// the app may send many requests..
// ----------------------------------------------------------------------------------------------

// Build a path using an invoice ID.
sbPath := TChilkatStringBuilder.Create(Self);
sbPath.Append('/v1/invoicing/invoices/invoice_id/qr-code');
numReplacements := sbPath.Replace('invoice_id','INV2-ZG2H-HKAW-PMWU-N6ZR');

rest.AddHeader('Authorization',sbAuth.GetAsString());
// A 500x500 image results in a PNG file of approx. 4K bytes in size.
rest.AddQueryParam('width','500');
rest.AddQueryParam('height','500');
rest.AddQueryParam('action','pay');

// Send the GET request and get the PNG image data as base64.
// A successful JSON response looks like this:
// {"image":"iVBORw0KGgoAA....AASUVORK5CYII="}
sbJsonResponse := TChilkatStringBuilder.Create(Self);
success := rest.FullRequestNoBodySb('GET',sbPath.GetAsString(),sbJsonResponse.ControlInterface);
if (success <> 1) then
  begin
    Memo1.Lines.Add(rest.LastErrorText);
    Exit;
  end;

json := TChilkatJsonObject.Create(Self);
json.EmitCompact := 0;
json.LoadSb(sbJsonResponse.ControlInterface);

Memo1.Lines.Add('Response Status Code = ' + IntToStr(rest.ResponseStatusCode));

// Did we get a 200 success response?
if (rest.ResponseStatusCode <> 200) then
  begin
    Memo1.Lines.Add(json.Emit());
    Memo1.Lines.Add('Failed.');
    Exit;
  end;

// If the 200 response is received, the response body contains the PNG data.
// Save the PNG to a file.
pngData := TChilkatBinData.Create(Self);
pngData.AppendEncoded(json.StringOf('image'),'base64');
success := pngData.WriteFile('qa_output/paypal_qr_code.png');
if (success = 0) then
  begin
    Memo1.Lines.Add('Failed to save PNG file.');
    Exit;
  end;

Memo1.Lines.Add('Success.');
end;