unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, ExtDlgs, IdHTTP, cefvcl, ceflib;

const
  MENU_ID_SAVE_IMAGE_AS = Ord(MENU_ID_USER_FIRST) + 1;

type
  TDownloader = class(TThread)
  private
    FURL: string;
    FFileName: string;
  protected
    procedure Execute; override;
  public
    constructor Create(const URL, FileName: string); reintroduce;
  end;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Chromium1: TChromium;
    SavePictureDialog1: TSavePictureDialog;
    procedure FormCreate(Sender: TObject);
    procedure Chromium1BeforeContextMenu(Sender: TObject; const browser: ICefBrowser;
      const frame: ICefFrame; const params: ICefContextMenuParams; const model: ICefMenuModel);
    procedure Chromium1ContextMenuCommand(Sender: TObject; const browser: ICefBrowser;
      const frame: ICefFrame; const params: ICefContextMenuParams; commandId: Integer;
      eventFlags: TCefEventFlags; out Result: Boolean);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

{ TDownloader }

constructor TDownloader.Create(const URL, FileName: string);
begin
  inherited Create(False);
  FreeOnTerminate := True;
  FURL := URL;
  FFileName := FileName;
end;

procedure TDownloader.Execute;
var
  HTTPClient: TIdHTTP;
  FileStream: TFileStream;
begin
  try
    HTTPClient := TIdHTTP.Create;
    try
      FileStream := TFileStream.Create(FFileName, fmCreate);
      try
        HTTPClient.Get(FURL, FileStream);
      finally
        FileStream.Free;
      end;
    finally
      HTTPClient.Free;
    end;
  except
    // error handling ignored for this example
  end;
end;

{ TForm1 }

procedure TForm1.FormCreate(Sender: TObject);
begin
  Chromium1.Load('http://www.google.com/');
end;

procedure TForm1.Chromium1BeforeContextMenu(Sender: TObject; const browser: ICefBrowser;
  const frame: ICefFrame; const params: ICefContextMenuParams; const model: ICefMenuModel);
begin
  if (CM_TYPEFLAG_MEDIA in params.TypeFlags) and (params.MediaType = CM_MEDIATYPE_IMAGE) then
    model.AddItem(MENU_ID_SAVE_IMAGE_AS, 'Save image as...');
end;

procedure TForm1.Chromium1ContextMenuCommand(Sender: TObject; const browser: ICefBrowser;
  const frame: ICefFrame; const params: ICefContextMenuParams; commandId: Integer;
  eventFlags: TCefEventFlags; out Result: Boolean);
var
  SaveDialog: TSavePictureDialog;
begin
  if (commandId = MENU_ID_SAVE_IMAGE_AS) then
  begin
    SaveDialog := TSavePictureDialog.Create(nil);
    try
      // SaveDialog.FileName := <here you can extract file name from params.SourceUrl>;
      // SaveDialog.DefaultExt := <here you can extract file ext from params.SourceUrl>;
      if SaveDialog.Execute then
        TDownloader.Create(params.SourceUrl, SaveDialog.FileName);
    finally
      SaveDialog.Free;
    end;
  end;
end;

end.