delphi - 如何在 freepascal/lazarus 的子进程中实现 cef3 渲染进程处理程序

Question

我正在尝试将 fpcef3 渲染进程处理程序实现为子进程:

遵循 fpcef3 github repo 上提供的示例，我已经成功创建了一个渲染进程处理程序子进程:

Program subprocess;

{$mode objfpc}{$H+}

Uses
  {$IFDEF UNIX}{$IFDEF UseCThreads}
  cthreads,
  {$ENDIF}{$ENDIF}
  cef3lib, cef3types, cef3api, Handler;

Var
  Args : TCefMainArgs;

begin
  CefLoadLibrary;
  CefRenderProcessHandler := TCustomRenderProcessHandler.Create;

  {$IFDEF WINDOWS}
  Args.instance := HINSTANCE();

  Halt(cef_execute_process(@Args, nil, nil));
  {$ELSE}
  Args.argc := argc;
  Args.argv := argv;

  Halt(cef_execute_process(@Args, nil, nil));
  {$ENDIF}
end. 

TCustomRenderProcessHandler 与示例子目录中的 JavaScript 示例提供的处理程序相同:

Unit Handler;

{$MODE objfpc}{$H+}

(*
 * Everything in here is called from a render process, so there is no access to GUI and all the
 * data of the main process.
 *)

Interface

Uses
  Classes, SysUtils,
  cef3types, cef3intf, cef3ref, cef3own, cef3lib;

Type
  { Custom handler for the render process }
  TCustomRenderProcessHandler = class(TCefRenderProcessHandlerOwn)
  protected
    // Test Window Bindings
    procedure OnContextCreated(const browser: ICefBrowser; const frame: ICefFrame; const context: ICefv8Context); override;
    // Test Extension
    procedure OnWebKitInitialized; override;
  end;

  TMyHandler = class(TCefv8HandlerOwn)
  protected
  function Execute(const name: ustring; const obj: ICefv8Value;
    const arguments: ICefv8ValueArray; var retval: ICefv8Value;
    var exception: ustring): Boolean; override;
  end;

Implementation

Var
  mystr : String;

{ TMyHandler }

function TMyHandler.Execute(const name : ustring; const obj : ICefv8Value;
  const arguments : ICefv8ValueArray; var retval : ICefv8Value;
  var exception : ustring) : Boolean;
begin
  // return a value
  //retval := TCefv8ValueRef.NewString('TMyHandler');
  retval := TCefv8ValueRef.NewDate(Now);

  Result := True;
end;

{ TCustomRenderProcessHandler }

procedure TCustomRenderProcessHandler.OnContextCreated(const browser : ICefBrowser;
  const frame : ICefFrame; const context : ICefv8Context);
Var
  myWin : ICefv8Value;
  args  : ICefv8ValueArray;
begin
  myWin := context.GetGlobal;
  mystr := 'a test string';
  SetLength(args, 1);
  args[0] := TCefv8ValueRef.NewString(mystr);
  myWin.SetValueByKey('myval', args[0], []);
end;

procedure TCustomRenderProcessHandler.OnWebKitInitialized;
Var
  Code: ustring;
begin
  Code :=
   'var cef;'+
   'if (!cef)'+
   '  cef = {};'+
   'if (!cef.test)'+
   '  cef.test = {};'+
   '(function() {'+
   '  cef.test.__defineGetter__(''test_param'', function() {'+
   '    native function GetTestParam();'+
   '    return GetTestParam();'+
   '  });'+
   '  cef.test.__defineSetter__(''test_param'', function(b) {'+
   '    native function SetTestParam();'+
   '    if(b) SetTestParam(b);'+
   '  });'+
   '  cef.test.test_object = function() {'+
   '    native function GetTestObject();'+
   '    return GetTestObject();'+
   '  };'+
   '})();';

  CefRegisterExtension('example/v8', Code, TMyHandler.Create as ICefv8Handler);
end;

end.

最后，在主进程的主要形式中，我提供了子进程的路径:

procedure TForm1.FormCreate(Sender: TObject);
begin
  CefSingleProcess := False;

  //CefRenderProcessHandler := TCustomRenderProcessHandler.Create;
  CefBrowserSubprocessPath := 'C:\Users\aludin\fpCEF3-master\Examples\SubProcess\subprocess64.exe'
end;     

当我启动主应用程序时， Chrome 浏览器会正确显示，但是处理程序不会被调用(但是我可以看到子进程已启动)。初始化处理程序时我做错了什么？

感谢您的帮助!

Answer 1

好吧，终于弄清楚了，在花了这么多时间之后，我想在这里添加一些咒语。

在深入研究了 fpcef3 源代码并单步执行主进程后，我意识到您需要创建一个 ICefApp 应用程序实例并将自定义渲染进程处理程序分配给该应用程序。因此，为了简化我的生活并避免实现 ICefApp 接口(interface)，我“劫持”了主进程内部使用的类。更新后的子流程实现现在由以下代码给出:

Program subprocess;

{$mode objfpc}{$H+}

Uses
  {$IFDEF UNIX}{$IFDEF UseCThreads}
  cthreads,
  {$ENDIF}{$ENDIF}
  cef3lib, cef3types, cef3api, cef3own, cef3intf, Handler;

Var
  Args : TCefMainArgs;
  app : ICefApp;

begin
  CefLoadLibrary;
  CefRenderProcessHandler := TCustomRenderProcessHandler.Create;
  app := TInternalApp.Create;
  {$IFDEF WINDOWS}
  Args.instance := HINSTANCE();

  Halt(cef_execute_process(@Args, CefGetData(app), nil));
  {$ELSE}
  Args.argc := argc;
  Args.argv := argv;

  Halt(cef_execute_process(@Args, CefGetData(app), nil));
  {$ENDIF}
end.

现在，ICefApp 实例将使用分配给 CefRenderProcessHandler 的渲染进程处理程序。最后请注意如何修改 cef_execute_process() 以将应用程序作为附加参数。