(Delphi DLL) Download Photo to a File

Assuming we have the ID of a Photo, this example demonstrates how to download the photo image data to a file.

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

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Http, OAuth2, Rest, StringBuilder, JsonObject;

...

procedure TForm1.Button1Click(Sender: TObject);
var
oauth2: HCkOAuth2;
rest: HCkRest;
success: Boolean;
photoId: PWideChar;
sbPath: HCkStringBuilder;
responseJson: PWideChar;
json: HCkJsonObject;
imageUrl: PWideChar;
sbImageUrl: HCkStringBuilder;
sbToPath: HCkStringBuilder;
bCaseSensitive: Boolean;
http: HCkHttp;

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

// This example assumes a previously obtained an access token
oauth2 := CkOAuth2_Create();
CkOAuth2_putAccessToken(oauth2,'FACEBOOK-ACCESS-TOKEN');

rest := CkRest_Create();

// Connect to Facebook...
success := CkRest_Connect(rest,'graph.facebook.com',443,True,True);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkRest__lastErrorText(rest));
    Exit;
  end;

// Provide the authentication credentials (i.e. the access key)
CkRest_SetAuthOAuth2(rest,oauth2);

// Assumes we've already obtained a Photo ID.
photoId := '10210199026347451';

sbPath := CkStringBuilder_Create();
CkStringBuilder_Append(sbPath,'/v2.7/');
CkStringBuilder_Append(sbPath,photoId);

// First we're going to get the photo informaton so we can get the URL of the image file data.
// Select the fields we want.
// See https://developers.facebook.com/docs/graph-api/reference/photo/
CkRest_AddQueryParam(rest,'fields','id,album,images');

responseJson := CkRest__fullRequestNoBody(rest,'GET',CkStringBuilder__getAsString(sbPath));
if (CkRest_getLastMethodSuccess(rest) <> True) then
  begin
    Memo1.Lines.Add(CkRest__lastErrorText(rest));
    Exit;
  end;

json := CkJsonObject_Create();
CkJsonObject_putEmitCompact(json,False);
CkJsonObject_Load(json,responseJson);

// Show the JSON in human-readable format.
Memo1.Lines.Add(CkJsonObject__emit(json));

// Get the image URL.
imageUrl := CkJsonObject__stringOf(json,'images[0].source');
Memo1.Lines.Add('Downloading from ' + imageUrl);

sbImageUrl := CkStringBuilder_Create();
CkStringBuilder_Append(sbImageUrl,imageUrl);

// Build the output local file path.
sbToPath := CkStringBuilder_Create();
CkStringBuilder_Append(sbToPath,'qa_output/fb');
CkStringBuilder_Append(sbToPath,CkJsonObject__stringOf(json,'id'));
bCaseSensitive := False;
if (CkStringBuilder_Contains(sbImageUrl,'.jpg',bCaseSensitive) = True) then
  begin
    CkStringBuilder_Append(sbToPath,'.jpg');
  end
else
  begin
    CkStringBuilder_Append(sbToPath,'.png');
  end;
Memo1.Lines.Add('Downloading to ' + CkStringBuilder__getAsString(sbToPath));

// Download using Chilkat HTTP.
http := CkHttp_Create();
success := CkHttp_Download(http,imageUrl,CkStringBuilder__getAsString(sbToPath));
if (success <> True) then
  begin
    Memo1.Lines.Add(CkHttp__lastErrorText(http));
  end
else
  begin
    Memo1.Lines.Add('Downloaded.');
  end;

CkOAuth2_Dispose(oauth2);
CkRest_Dispose(rest);
CkStringBuilder_Dispose(sbPath);
CkJsonObject_Dispose(json);
CkStringBuilder_Dispose(sbImageUrl);
CkStringBuilder_Dispose(sbToPath);
CkHttp_Dispose(http);

end;