为 TFrame 的后代执行了两次加载过程

Question

我已经注册为组件 a TFrame 的后代 class 并且我注意到 Loaded 过程被执行了两次：

运行时间：

  TMyFrame = class(TFrame)
  private
  protected
    procedure Loaded(); override;
  public
    constructor Create(AOwner : TComponent); override;
  end;

constructor TMyFrame.Create(AOwner : TComponent);
begin
  ShowMessage('Before TMyFrame.Create');
  inherited Create(AOwner);
  ShowMessage('After TMyFrame.Create');
end;

procedure TMyFrame.Loaded();
begin
  ShowMessage('Before TMyFrame.Loaded');
  inherited;
  ShowMessage('After TMyFrame.Loaded');
end;

设计时间：

procedure Register;
begin
  RegisterComponents('Test', [TMyFrame]);
end;

输出：

在运行时，在创建一个包含 TMyFrame 组件的表单时。

Before TMyFrame.Create

Before TMyFrame.Loaded

After TMyFrame.Loaded

After TMyFrame.Create

Before TMyFrame.Loaded

After TMyFrame.Loaded

在设计时，将 TMyFrame 添加到表单时：

Before TMyFrame.Create

Before TMyFrame.Loaded

After TMyFrame.Loaded

After TMyFrame.Create

在设计时，打开一个包含 TMyFrame 组件的表单：

Before TMyFrame.Create

Before TMyFrame.Loaded

After TMyFrame.Loaded

After TMyFrame.Create

Before TMyFrame.Loaded

After TMyFrame.Loaded

为什么Loaded过程被执行了两次？如何避免这种情况？

Answer 1

此行为是设计好的。

Loaded

Loaded may be called multiple times on inherited forms. It is called every time a level of inheritance is streamed in. Do not allocate memory in an overridden Loaded method without first checking that the memory has not been allocated in a previous call.

为 TFrame 的后代执行了两次加载过程

Loaded procedure executed twice for TFrame's descendant

delphi

components

tframe