如何在运行时创建组件并对其进行操作(更改属性等)?
这要看它是可视或不可视组件。原则是一样的,但每种组件都有一些额外的考虑因素。
对于非可视组件
var
C: TMyComponent;
begin
C := TMyComponent.Create(nil);
try
C.MyProperty := MyValue;
//...
finally
C.Free;
end;
end;
对于可视化组件:
本质上,可视化组件的创建方式与非可视化组件相同。但是,您需要设置一些额外的属性来使它们可见。
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;
对上面的代码进行一些解释:
Parent
属性可以使组件可见。如果忘记设置,您的组件将不会显示出来。(这很容易被忽略)如果你想要多个组件,你可以用同样的方法在一个循环中创建它们:
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;
这将在表单的左边界添加10个按钮。如果您想以后修改这些按钮,可以将它们存储在列表中。(TComponentList最适合,但还应看看本答案评论中的提议)。procedure TForm1.MyButtonClick(Sender: TObject);
var
Button: TButton;
begin
Button := Sender as TButton;
ShowMessage(Button.Caption + ' clicked');
end;
B := TButton.Create;
//...
B.OnClick := MyButtonClick;
为了简化运行时组件创建过程,您可以使用GExperts。
示例(使用此方法生成的TButton创建代码):
var
btnTest: TButton;
btnTest := TButton.Create(Self);
with btnTest do
begin
Name := 'btnTest';
Parent := Self;
Left := 272;
Top := 120;
Width := 161;
Height := 41;
Caption := 'Component creation test';
Default := True;
ParentFont := False;
TabOrder := 0;
end;
我想补充一点,当动态添加控件时,建议将它们添加到一个对象列表(TObjectList)中,如@Despatcher在<1>中所建议的那样。
procedure Tform1.AnyButtonClick(Sender: TObject);
begin
If Sender is TButton then
begin
Case Tbutton(Sender).Tag of
.
.
.
// Or You can use the index in the list or some other property
// you have to decide what to do
// Or similar :)
end;
end;
procedure TForm1.BtnAddComponent(Sender: TObJect)
var
AButton: TButton;
begin
AButton := TButton.Create(self);
Abutton. Parent := [Self], [Panel1] [AnOther Visual Control];
AButton.OnClick := AnyButtonClick;
// Set Height and width and caption ect.
.
.
.
AButton.Tag := MyList.Add(AButton);
end;
您需要将Unit 'Contnrs'添加到您的Uses列表中。
即System.Contnrs.pas基本容器单元
您可以拥有多个对象列表。
我建议为您使用的每种控件类型使用TObjectList,例如:
Interface
Uses Contnrs;
Type
TMyForm = class(TForm)
private
{ Private declarations }
public
{ Public declarations }
end;
Var
MyForm: TMyForm;
checkBoxCntrlsList: TObjectList; //a list for the checkBoxes I will createin a TPanel
comboboxCntrlsList: TObjectList; //a list of comboBoxes that I will create in some Form Container
Var comboBox: TComboBox;
I: Integer;
begin
For I = 0 to comboboxCntrlsList.Count -1 do // or however you like to identify the control you are accessing such as using the tag property as @Despatcher said
Begin
comboBox := comboboxCntrlsList.Items[I] as TComboBox;
...... your code here
End;
end;
这样你就可以使用该控件的方法和属性了。不要忘记创建TObjectLists,可以在表单创建事件中进行...
checkBoxCntrlsList := TObjectList.Create;
comboboxCntrlsList := TObjectList.Create;
In Form1 Public
MyList: TObjectList;
procedure AnyButtonClick(Sender: TObject);
//你可以更加复杂地声明TNotifyevents并将其分配,但让我们保持简单:)
procedure Tform1.AnyButtonClick(Sender: TObject);
begin
If Sender is TButton then
begin
Case Tbutton(Sender).Tag of
.
.
.
// Or You can use the index in the list or some other property
// you have to decide what to do
// Or similar :)
end;
end;
procedure TForm1.BtnAddComponent(Sender: TObJect)
var
AButton: TButton;
begin
AButton := TButton.Create(self);
Abutton. Parent := [Self], [Panel1] [AnOther Visual Control];
AButton.OnClick := AnyButtonClick;
// Set Height and width and caption ect.
.
.
.
AButton.Tag := MyList.Add(AButton);
end;
一个对象列表可以包含任何可视或不可视的对象,但这会增加额外的开销,需要排序哪些项目是哪些 - 如果您想在类似面板上拥有多个动态控件,则最好拥有相关列表。
注意:像其他评论者一样,我可能为了简洁而过于简化,但我希望您能理解。您需要一种机制来管理创建后的对象,而列表非常适合处理此类事情。
在研究“使用基于XML的模板创建Delphi表单”时,我发现了一些有用的东西,指出了RTTI并使用开放式工具API(我认为是ToolsApi.pas)。请查看该单元中的接口。
非常简单。调用Create函数。例如:
procedure test
var
b : TButton;
begin
b:=TButton.Create(nil);
b.visible:=false;
end;
这将在运行时创建一个组件(TButton 是一个组件),并设置可见属性。
这是一个模拟在Evernote上使用按钮标签的例子
unit Unit7;
interface
uses
Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes,Vcl.Graphics,
Vcl.Controls, Vcl.Forms, Vcl.Dialogs, CHButton, Vcl.ExtCtrls, RzPanel, CHPanel, RzCommon,RzBmpBtn, Vcl.StdCtrls;
type
// This is panel Button
TButtonClose = class (TRzPanel)
CloseButton : TRzBmpButton;
procedure CloseButtonClick(Sender: TObject);
procedure CloseButtonMouseEnter(Sender: TObject);
procedure MouseDown(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
procedure MouseUp(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
public
constructor Create(AOwner: TComponent); override;
destructor Destroy; override;
end;
TForm7 = class(TForm)
CHButton1: TCHButton;
RzPanel1: TRzPanel;
RzBmpButton1: TRzBmpButton;
procedure CHButton1Click(Sender: TObject);
procedure RzBmpButton1Click(Sender: TObject);
procedure RzPanel1MouseDown(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
procedure RzPanel1MouseUp(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
procedure RzPanel1MouseEnter(Sender: TObject);
procedure RzBmpButton1MouseEnter(Sender: TObject);
procedure FormMouseEnter(Sender: TObject);
procedure FormCreate(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;
var
Form7: TForm7;
MyCloseButton : TButtonClose;
implementation
{$R *.dfm}
// constructor for on the fly component created
constructor TButtonClose.Create(AOwner: TComponent);
begin
inherited Create(AOwner);
// Set Events for the component
Self.OnMouseEnter := Self.CloseButtonMouseEnter;
Self.OnMouseDown := Self.MouseDown;
Self.OnMouseUp := Self.MouseUp;
Self.Height := 25;
// Close button on top panel Button
// Inherited from Raize Bitmap Button
CloseButton := TRzBmpButton.Create(self);
// Set On Click Event for Close Button
CloseButton.OnClick := Self.CloseButtonClick;
// Place Close Button on Panel Button
CloseButton.Parent := self;
CloseButton.Left := 10;
CloseButton.Top := 5;
CloseButton.Visible := False;
// Setting the image for the button
CloseButton.Bitmaps.Up.LoadFromFile(ExtractFilePath(Application.ExeName)+'\close.bmp');
end;
procedure TButtonClose.CloseButtonClick(Sender: TObject);
begin
// Free the parent (Panel Button)
TControl(Sender).Parent.Free;
end;
procedure TButtonClose.CloseButtonMouseEnter(Sender: TObject);
begin
// Show the Close button
CloseButton.Visible := True;
end;
procedure TButtonClose.MouseDown(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
// Emulate Button down state, since it is panel
TRzPanel(Sender).BorderOuter := fsLowered;
end;
procedure TButtonClose.MouseUp(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
// Emulate Button up state, since it is panel
TRzPanel(Sender).BorderOuter := fsRaised;
end;
destructor TButtonClose.Destroy;
begin
inherited Destroy;
end;
procedure TForm7.FormCreate(Sender: TObject);
begin
// Create Panel Button on the fly
MyCloseButton := TButtonClose.Create(self);
MyCloseButton.Caption := 'My Button';
MyCloseButton.Left := 10;
MyCloseButton.Top := 10;
// Don't forget to place component on the form
MyCloseButton.Parent := self;
end;
procedure TForm7.FormMouseEnter(Sender: TObject);
begin
if Assigned(RzBmpButton1) then
RzBmpButton1.Visible := False;
// Hide when mouse leave the button
// Check first if myCloseButton Assigned or not before set visible property
if Assigned(MyCloseButton.CloseButton) then
MyCloseButton.CloseButton.Visible := False;
end;
procedure TForm7.RzBmpButton1Click(Sender: TObject);
begin
TControl(Sender).Parent.Free;
end;
procedure TForm7.RzBmpButton1MouseEnter(Sender: TObject);
begin
RzBmpButton1.Visible := True;
end;
procedure TForm7.RzPanel1MouseDown(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
TRzPanel(Sender).BorderOuter := fsLowered;
end;
procedure TForm7.RzPanel1MouseEnter(Sender: TObject);
begin
RzBmpButton1.Visible := True;
end;
procedure TForm7.RzPanel1MouseUp(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
TRzPanel(Sender).BorderOuter := fsRaised;
end;
procedure TForm7.CHButton1Click(Sender: TObject);
begin
FreeAndNil(Sender);
end;
end.