在运行时创建组件 - Delphi [英] Creating components at runtime - Delphi

问题描述

如何在运行时创建组件然后使用它(更改属性等)?

How can I create a component at runtime and then work with it (changing properties, etc.)?

推荐答案

这取决于它是可视组件还是非可视组件.原理是一样的，但每种组件都有一些额外的注意事项.

It depends if it is a visual or non-visual component. The principle is the same, but there are some additional considerations for each kind of component.

对于非视觉组件

var
  C: TMyComponent;
begin
  C := TMyComponent.Create(nil);
  try
    C.MyProperty := MyValue;
    //...
  finally
    C.Free;
  end;
end;

对于视觉组件:

本质上，可视化组件的创建方式与非可视化组件的创建方式相同.但是您必须设置一些额外的属性才能使它们可见.

In essence visual components are created in the the same way as non-visual components. But you have to set some additional properties to make them visible.

var
  C: TMyVisualComponent;
begin
  C := TMyVisualComponent.Create(Self);
  C.Left := 100;
  C.Top := 100;
  C.Width := 400;
  C.Height := 300;
  C.Visible := True;
  C.Parent := Self; //Any container: form, panel, ...

  C.MyProperty := MyValue,
  //...
end;

对上面代码的一些解释:

A few explanations to the code above:

• 通过设置组件的所有者(构造函数的参数)，当拥有的表单被销毁时，组件也会被销毁.
• 设置 Parent 属性使组件可见.如果您忘记了它，您的组件将不会显示.(很容易错过那个 :) )

• By setting the owner of the component (the parameter of the constructor) the component gets destroyed when the owning form gets destroyed.
• Setting the Parent property makes the component visible. If you forget it your component will not be displayed. (It's easy to miss that one :) )

如果您需要多个组件，您可以执行与上述相同但在循环中的操作:

If you want many components you can do the same as above but in a loop:

var
  B: TButton;
  i: Integer;
begin
  for i := 0 to 9 do
  begin
    B := TButton.Create(Self);
    B.Caption := Format('Button %d', [i]);
    B.Parent := Self;
    B.Height := 23;
    B.Width := 100;
    B.Left := 10;
    B.Top := 10 + i * 25;
  end;
end;

这将在表单的左边框添加 10 个按钮.如果以后要修改按钮，可以将它们存储在列表中.(TComponentList 最适合，但也请查看来自对此答案的评论的建议)

This will add 10 buttons at the left border of the form. If you want to modify the buttons later, you can store them in a list. (TComponentList ist best suited, but also take a look at the proposals from the comments to this answer)

如何分配事件处理程序:

您必须创建一个事件处理程序方法并将其分配给事件属性.

You have to create an event handler method and assign it to the event property.

procedure TForm1.MyButtonClick(Sender: TObject);
var
  Button: TButton;
begin
  Button := Sender as TButton; 
  ShowMessage(Button.Caption + ' clicked');
end;

B := TButton.Create;
//...
B.OnClick := MyButtonClick;

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